Pozzolan cement compositions
This is a continuation, of application Ser. No. 899,699, filed Apr. 24, 1978, now abandoned which was a continuation-in-part of Ser. No. 823,321, filed Aug. 11, 1977 now abandoned, which was a continuation-in-part of Ser. No. 721,050, filed Sept. 7, 1976 (now abandoned). 
    
    
     BACKGROUND 
     The present invention relates to cement compositions utilizing a pozzolan material, preferably fly ash. One of the principal advantages of the present invention is that it provides cement compositions which are significantly cheaper per unit volume than conventional cement compositions having essentially the same structural properties. This result is achieved through proper proportioning of the various ingredients in the cement composition and the substitution of relatively large amounts of inexpensive pozzolan material for the more expensive cementitious ingredients normally utilized. 
     It has been known for many years that various finely divided, silicious materials react with lime in the presence of moisture to produce cementitious material which may be mixed with sand and stone to form a product similar to modern concrete. These silicious materials, which are commonly referred to as pozzolans, occur naturally or are by-products of various manufacturing processes. Examples of pozzolan materials include blast furnace slag, volcanic ash, calcined shale, trass, pumice, diatomaceous earth, silicious clays, and fly ash, which is the fine, solid by-product contained in the gases from the combustion of pulverized coal. With the advent of increasing public environmental concerns and the resulting limitations imposed on gaseous and particulate emissions from such combustion reactions, increasingly large amounts of fly ash are being recovered from the stack gases of commercial coal burning facilities, particularly high efficiency electric power generating plants. Despite the resulting availability of considerable quantities of fly ash, at present there is no major commercial use for fly ash. 
     Fly ash, as well as other pozzolan materials, have been utilized to replace a portion of the more expensive cementitious ingredients conventionally utilized in various cement compositions, but full utilization of fly ash has not been achieved. The primary obstacle to the use of larger proportions of fly ash in these cement compositions is that the reaction of pozzolan materials, including fly ash, with lime is slow compared to the normal cement reaction. Thus, pozzolan containing cement compositions have an early compressive strength (typically measured at seven or twenty-eight days) which is significantly less than similar cement compositions based on conventional cementitious materials, such as Portland cement. If pozzolan is substituted for too large a proportion of the cement, the resulting cement composition will have a poor initial strength and will require additional time prior to imposition of the service load. It may be necessary to provide external support for the cement composition until the pozzolanic reaction has proceeded sufficiently so that the cement composition is self-supporting. 
     The slow curing time of cement compositions having a high proportion of pozzolan material is unacceptable or undesirable for most commercial applications. Attempts have been made to solve this problem by utilizing heat to accelerate the curing rate and by adding large amounts of excess lime and/or various chemicals. These techniques have produced various specialized products, but they have not accelerated the pozzolanic reaction sufficiently to be useful in preparing cement compositions suitable for a broad range of structural applications. 
     The present invention concerns cement compositions which realize the economic benefits of using larger amounts of pozzolan material. This result is achieved by properly proportioning the ingredients in the cement composition and by including in the composition certain alkali metal ions and, in addition, anionic constituents capable of forming complexes with ferric ions, i.e., iron complexing agents. By utilizing the appropriate amounts of cement, pozzolan, water, and fine aggregate, it is possible to minimize the void content of the cement composition and to insure maximum compressive strength. The addition of relatively large amounts of sodium, potassium, and/or lithium ions apparently accelerates the pozzolanic reaction and makes it possible to add the larger amounts of pozzolan material, in the proper proportion to the other ingredients of the cement composition, without incurring a concomitant loss in early compressive strength. The iron complexing agents assist in promoting early compressive strength by chemically tieing up ferric ions which under normal circumstances would engage in chemical reactions inhibiting the cementitious reactions necessary to the development of compressive strength. 
     Because these benefits can be achieved when the requisite alkali metal ions and iron complexing anions are provided in the form of sodium chloride, the present invention has the further significant advantage that the cement compositions can be prepared from sea water or other brackish waters. Prior to the present invention it was generally believed that the incorporation of sea water in cement compositions would be deleterious to the product. The present invention now makes it possible to prepare relatively inexpensive cement compositions with sea water, an advantage which is particularly useful in localities where sea water is more readily available than fresh water. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a cement composition which maximizes the substitution of relatively inexpensive pozzolan material for Portland cement. 
     The cement compositions of the present invention comprise cement, a pozzolan material, fine aggregate, air, water, at least one alkali metal constituent selected from the group consisting of sodium, potassium, and lithium ions, and at least one anionic constituent which is capable of forming complexes with ferric iron ions, is soluble in water, and forms a calcium salt which is also water soluble; wherein the alkali metal constituent is present in an amount up to approximately 4.0 percent by weight, in terms of the equivalent weight of sodium ions, of the pozzolan material; the anionic constituent is present in an amount up to approximately 6.0 percent by weight, in terms of the equivalent weight of chloride ions, of the pozzolan material, and the cement composition is further characterized by: 
     (a) having a solid volume ratio of cement to the pozzolan material within the range of approximately 0.05 to 2.0; 
     (b) having a ratio of the volume of paste (fly ash, cement, air, and water) to the solid volume of sand within the range of approximately 0.75 to 2.5; and 
     (c) having a ratio of the solid volume of cement to the volume of mortar less than about 0.19. 
     It is an object of this invention to provide a cement composition which maximizes the substitution of relatively inexpensive pozzolan material, such as fly ash, for more expensive cement. 
     It is an object of the invention to provide a cement composition which maximizes the substitution of relatively inexpensive pozzolan material for cement without reducing the early compressive strength of the cement composition. 
     It is a further object of the invention to provide a cement composition which is significantly less expensive than an equal volume of a conventional cement composition having equivalent structural properties. 
     It is another object of this invention to provide an economical cement composition which can be prepared from brackish or sea water. 
     Further objects of the present invention will be apparent from the detailed description of the invention which follows. 
    
    
     DESCRIPTION OF THE DRAWING 
     FIG. 1 is a graph depicting the 28-day compressive strength versus the cement content of various cement compositions, including commercially available cement compositions without pozzolan material (IA), cement compositions containing pozzolan material in amounts commercially utilized at the present time (IB), and cement compositions containing a large proportion of pozzolan material in accordance with the present invention (ID). 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to cement compositions of all types in which Portland cement or similar cementitious material reacts with water to bind together various inert ingredients, such as sand, stone, crushed rock, etc. As used herein the term &#34;cement composition&#34; refers to all such cemetitious mixtures including, for example, those generally designated in the art as mortar, grout, and concrete. The present invention is applicable, but not limited, to the following types of cement compositions: ready mixed concrete compositions, prefabricated concrete structural elements prepared by autoclaving or steam curing cement compositions, concrete compositions utilized in large mass structures, such as gravity dams, and concrete compositions employed as highway bases and surfaces. These cement compositions may be employed with additional reinforcing elements conventionally utilized in the art to supplement their structural properties. 
     Despite the inherent economic advantages associated with the substitution of pozzolan materials, such as fly ash, typical pozzolan cement compositions, such as concrete, presently used in commercial practice contain enough pozzolan material to replace only about 20 to 30 percent by weight of the cement normally present. (If fly ash is substituted for 30 percent of the cement, the cement:fly ash ratio, as hereinafter defined, is approximately 2.24). The primary obstacle to the utilization or larger proportions of fly ash is the slow reaction rate of pozzolan material compared with the normal reaction of cementitious materials such as Portland cement. Attempts to substitute larger amounts of pozzolan material for cement have resulted in cement compositions having an undesirably slow setting time and unacceptably poor early strength characteristics. As a result costly delays are encountered before the cement composition can bear a service load. Prior to the present invention attempts to realize the economic advantages associated with the utilization of large amounts of pozzolan material in cement compositions have been unsuccessful largely because of the undesirable properties of the resulting products. 
     The present invention is applicable to cement compositions containing pozzolan and cement, in relative proportions such that the cement-pozzolan ratio is within the range of approximately 0.05 to 2.0. Preferably, the cement-pozzolan ratio is within the range of approximately 0.1 to 2.0. For present purposes the &#34;cement:pozzolan ratio&#34; means the ratio of the solid volume of dry cement to the solid volume of dry pozzolan material contained in the cement composition. As used herein the term &#34;solid volume&#34; (particularly as applied to the proportions of cement, pozzolan material, and fine aggregate or sand) means the volume of the solid constituent exclusive of its voids and is determined by dividing the weight of the material by its specific gravity. 
     The cement compositions of the present invention include cement, pozzolan, fine aggregate or sand, water, and entrained and entrapped air, which enters the cement composition during mixing of these ingredients. The cement constituents which may be utilized include any of the typical Portland cements known in the art, such as those meeting the description of ASTM Standard C 150-74, Types I, II, and III. However, the proportion of cement contained in the present cement compositions is considerably less than that normally utilized in conventional cement compositions having comparable structural properties. 
     The pozzolan materials which may be utilized include any of the materials falling within the definition of Class N, F, or S set forth in ASTM Standard C 618-72. Suitable pozzolan materials include trass, volcanic ash, pumice, slag, diatomaceous earth, silicious clays, calcined shale, and fly ash. Fly ash is the preferred pozzolan material, because it is readily available, inexpensive, and has certain desirable physical properties. The shape and size distribution of fly ash particles improve the workability of cement compositions, and acceptable workability of such compositions containing fly ash and can generally be achieved with less water than with other pozzolan materials. This reduction in the water requirement aids in minimizing the void content of the cement composition and increases the compressive strength of the cement product. 
     The cement compositions also comprise fine aggregate or sand which may be any clean durable sand conventionally used in the art for preparing mortar or concrete. Suitable sands include those which are deficient in material passing through a No. 50 mesh screen. The amount of sand incorporated in the cement composition is determined by the volume of the cement composition and the strength properties which are desired, taking into account that the paste:sand ratio, as defined herein, must be kept within the defined range. 
     The cement composition also includes sufficient water to comply with ASTM and ACI standards for workability. Within these parameters it is desirable to minimize the quantity of water added to maximize the strength of the cement composition. 
     The cement compositions of the present invention may also include any of the chemical ingredients commonly known to those skilled in the art as &#34;chemical admixes&#34;. The basic types of chemical admixes presently utilized are set forth in ASTM Standard C 494-71 and are generally classified according to their function, i.e., whether they are utilized to retard or accelerate the cementitious chemical reactions, to reduce the water requirement, or for a combination of these reasons. The chemical admixes which are used commonly today include derivatives of lignosulfonic acid and its salts, hydroxylated carboxylic acids and their salts, and polymer derivatives of sugar. More recently certain chemical admixes known as &#34;super plasticizers&#34; or &#34;super water reducers&#34; have been employed which consist primarily of salts of organic sulfonates of the type RSO 3  Na where R is a complex organic group, frequently of high molecular weight, e.g. melamine, naphthalene, or lignin. One or more of these chemical admixes may be incorporated in the present cement compositions in the amounts conventionally utilized in the art. 
     The foregoing cement composition constituents may be combined in any manner conventionally utilized in the art and are generally mixed in accordance with the procedures set forth in ASTM Standard C-94. 
     During the curing and hardening of the cement composition air and water leave voids which cause weakness in the cured product. To maximize the early compressive strength properties of the present cement compositions it is desirable to minimize the voids in the cement composition, since an inverse relationship exists between the volume of such voids and the compressive strength of the cement composition. It has now been found that these voids are minimized, if enough pozzolan material is added to a mixture comprising cement, sand, water, and air so that the volume ratio of paste (cement, pozzolan, water, and air) to sand (fine aggregate) is in the range of approximately 0.75 to 2.5 and, preferably, in the range of approximately 1.0 to 2.0. For present purposes the &#34;paste:sand ratio&#34; means the ratio of the volume of the paste constituents (cement, pozzolan, water, and air) to the solid volume of dry sand (fine aggregate). Although the optimum paste:sand ratio for any specific cement composition depends on the type of sand and cementitious ingredients utilized, the optimum amount will fall within the foregoing range. 
     The early compressive strength is also increased by accelerating the pozzolanic reaction, i.e., the reaction between calcium hydroxide, which is formed during hydration of the normal cementitous components, with the silicates present in the pozzolan material to form additional calcium silicate. The rate of this reaction is dependent on three mechanisms. First, the rate of hydration of the cement controls the rate of formation of additional calcium hydroxide needed in the pozzolanic reaction. Chemicals which increase the hydration of cement itself will, therefore, increase the pozzolanic reaction concurrently taking place. Secondly, the rate of dissolution of silica from the pozzolanic material into the reaction medium will govern the availability of the other reactant silica. Thus, materials which stimulate the dissolution of silica will also increase the rate of the pozzolanic reaction by increasing the availability of silica for reaction with the calcium hydroxide. Finally, the rate of the pozzolanic reaction is influenced negatively by the formation of ferric hydroxide gel which retards the reaction of calcium hydroxide and silica. Iron and ferrous or ferric ions are components normally present in most pozzolanic materials, particularly fly ash, and are also present in most cements. However, the eventual controlled release of ferrous and ferric ions is beneficial and eliminates excess hydroxide ions, formed during the hydration or available from other chemical reducing or accelerating agents, which would tend to drive the reaction of calcium hydroxide with silica in the reverse direction. Thus, the pozzolanic reaction is accelerated by materials which initially form ferric ion complexes, such materials being generally referred to herein as iron complexing agents. 
     It has now been found that two of these factors determining the rate of the pozzolanic reaction can be positively influenced by the addition of one or more anionic constituents, meeting the following criteria: 
     (a) the anion forms ferric ion complexes; 
     (b) the anion is soluble in water; and 
     (c) the calcium salt of the anion is also soluble in water. 
     While the first criteria is important to the pozzolanic reaction for the reason set forth in the previous paragraph, the second two criteria assure that the anion will be available in the aqueous environment of the hardening cement compositions and that its calcium salt will not precipitate out of that environment or otherwise physically impede the cementitous and pozzolanic reactions taking place. 
     For purposes of the present invention an anion and its calcium salt are considered water soluble if they have a solubility approximately equal to the water solubility of calcium hydroxide and preferably in excess thereof. 
     Examples of anions which meet these three requirements and are useful in the present invention are chloride, bromide, nitrite, thiocyanate, cyanide, and lactate ions. One or more of the anions in this group may be employed in the cement compositions of the present invention. It has been noted that any measureable amount of these anions will have some identifiable effect on the pozzolanic reaction rate and the early compressive strength of the cement composition. The cement compositions may contain sufficient chloride ions to constitute up to approximately 6.0 percent by weight of the pozzolan material present and, preferably, from approximately 0.1 to 2.4 percent by weight of the pozzolan material. In cement compositions employing bromide, nitrite, thiocyanate, cyanide or lactate ions these ions should be present in an amount corresponding to equal quantities of chloride ions within the general and preferred ranges set out above. In cement compositions employing combinations of the anions the total amount of these ions should be maintained within the same general and preferred ranges. 
     A portion of the chloride, bromide, lactate, nitrite, thiocyanate, or cyanide ions may be replaced and supplemented by one or more ions selected from the group consisting of sulfate, thiosulfate, nitrate, sulfite, or silicylate ions. These ions do not fully meet the three criteria set forth previously. Sulfate, nitrate, sulfite, or silicylate ions are much weaker iron complexing agents in the alkaline environment of concrete than the ions identified in the previous paragraph, and the sulfate and sulfite ions are much less soluble in water. Thiosulfate is only a weak iron complexing agent in the alkaline environment of cement compositions and partially decomposes into sulfate which forms insufficiently soluble calcium sulfate in these compositions. Thus, although these ions are partially effective in complexing ferric ions in pozzolan cement compositions, they cannot be used to totally replace the chloride, bromide, nitrite, thiocyanate, cyanide, and/or lactate ions in the pozzolan cement compositions of this invention. Preferably the pozzolan cement compositions should always contain sufficient anions fully meeting the criteria previously set forth, such as those selected from the group consisting of chloride, bromide, nitrite, thiocyanate, cyanide, and/or lactate ions to constitute at least approximately 0.1 percent by weight, in terms of the equivalent weight of chloride ions, of the pozzolan material. In addition, one or more of the ions in the group consisting of thiosulfate, nitrate, sulfate, sulfite, or salicylate ions may be used in an amount such that the total amount of anions present from both groups, i.e., chloride, bromide, nitrite, thiocyanate, cyanide, lactate, thiosulfate, nitrate, sulfate, sulfite, and salicylate, is present in an amount up to approximately 6.0 percent by weight, in terms of the equivalent weight of chloride ions, of the pozzolan material. 
     It has been found that the pozzolanic reaction can be accelerated further by adding sufficient quantities of at least one alkali metal ion selected from the group consisting of sodium, potassium, and lithium ions. These ions apparently accelerate the pozzolanic reaction by the third means, i.e., by increasing the water solubility of the silicious constituents in the pozzolan material, thereby permitting the silica in solution to react with excess lime liberated by the hydration of the cement. 
     Any measurable amounts of sodium, potassium and/or lithium ions will have some identifiable effect in catalyzing the pozzolanic reaction and offsetting the reduction in early compressive strength usually associated with high pozzolan content cement compositions. If sodium ions are utilized, the cement composition should contain sodium ions in an amount comprising up to approximately 4.0 percent by weight of the pozzolan material present in the cement composition, and preferably, sufficient sodium ions should be present to constitute from approximately 0.2 to 1.6 percent by weight of the pozzolan material. In cement compositions employing potassium or lithium ions as the alkali ion constituent, the potassium or lithium ions may be present in amounts corresponding to equal quantities of sodium ions within the general and preferred ranges set out above. It is also possible to utilize mixtures of sodium, potassium, and/or lithium ions, with the total quantity of sodium potassium and/or lithium ions again being translated into the equivalent molecular weight of sodium ions. When alkali metal ions are added in amounts in excess of 4.0 percent by weight, in terms of the equivalent weight of sodium ions, of the pozzolan material, the beneficial effects are diminished, and after the water has evaporated from its surface, the exterior of such a cement composition is noticeably discolored by a powdery white residue. 
     The following are examples of pozzolan cement compositions within the present invention: 
     COMPOSITION 1 
     188 grams Type I cement 
     500 grams fly ash 
     1250 grams of a 50/50 mixture of sands from Ottawa, Illinois 
     224 milliliters of water 
     20 grams NaCl (1.57 percent sodium ions and 2.43 percent chloride ions per weight of fly ash) 
     0.29 cement:pozzolan ratio 
     1.09 paste:sand ratio 
     0.06 volume of cement:volume of mortar 
     COMPOSITION 2 
     188 grams Type I cement 
     500 grams fly ash 
     1250 grams of a 50/50 mixture of sands from Ottawa Illinois 
     217 milliliters of water 
     1.5 grams NaSCN 
     8.4 grams NaNO 3   
     9.6 grams Na 2  S 2  O 3  (1.10 percent sodium ions and the equivalent of 1.27 percent chloride ions per weight of fly ash) 
     0.29 cement:pozzolan ratio 
     1.07 paste:sand ratio 
     0.06 volume of cement:volume of mortar 
     COMPOSITION 3 
     188 grams Type I cement 
     500 grams fly ash 
     1250 grams of a 50/50 mixture of sands from Ottawa, Illinois 
     215 milliliters of water 
     2.5 grams NaSCN 
     10.0 grams NaNO 3   
     1.0 grams Na 2  SO 4  (0.8 percent sodium ions and the equivalent of 1.16 percent chloride ions per weight of the fly ash) 
     0.29 cement:pozzolan ratio 
     1.07 paste:sand ratio 
     0.06 volume of cement:volume of water 
     COMPOSITION 4 
     188 grams Type I cement 
     500 grams fly ash 
     1250 grams of a 50/50 mixture of sands from Ottawa, Illinois 
     207 milliliters of water 
     1.0 grams sodium silicylate 
     5.0 grams NaSCN 
     10.0 grams NaNO 3   
     3.18 grams Na 2  S 2  O 3  (1.04 percent sodium ions and the equivalent of 1.46 percent chloride ions per weight of the fly ash) 
     0.29 cement:pozzolan ratio 
     1.09 paste:sand ratio 
     0.06 volume of cement:volume of mortar 
     One of the preferred additives is sodium chloride which may be incorporated into the cement composition in the form of sea water. Sea water is particularly useful, because it contains appreciable amounts of potassium and sulfate ions in addition to sodium chloride. The following is a typical chemical analysis of the ionic constituents of sea water: 
     
         ______________________________________                                    
       Ion            (ppm)                                               
______________________________________                                    
       Sodium         10,000                                              
       Potassium      700                                                 
       Calcium        440                                                 
       Magnesium      1,316                                               
       Sulfate        2,515                                               
       Chloride       20,750                                              
______________________________________                                    
 
    
     The beneficial effect of sea water is particularly surprising, since heretofore it has been generally accepted that sea water is deleterious to cement compositions. The present invention now provides cement compositions utilizing sea water, thereby making cement compositions more readily available in areas where sea water is plentiful and fresh water relatively scarce. 
     In another specific embodiment it has been found that the benefits of the present invention can be achieved without adding an alkali metal constituent if chloride ion is added in the form of calcium chloride in an amount sufficient to comprise approximately 0.5 to 4.0 and preferably from approximately 0.5 to 3.0 percent by weight of the pozzolan material present and the other ingredients of the cement composition are added in accordance with the proportions described herein. These cement compositions may contain alkali metal ions, iron complexing ions and other anions in the amounts previously set forth. However, cement compositions in which chloride ion is added with an alkali metal constituent demonstrate larger early compressive strengths than analogous cement compositions in which the chloride ion is added as calcium chloride. 
     Another advantage of the present invention is that the benefits of using relatively large amounts of fly ash can be achieved without adding extraneous lime, i.e., lime other than that produced in situ by hydration of the cement. The cement compositions of the present invention, may tolerate extraneous lime in amounts up to approximately 4.0 percent by weight of the fly ash, although the setting time of the product is reduced. When additional lime is added in amounts exceeding about 4.0 percent by weight of the pozzolan material, the early strength of the cement composition is diminished. Accordingly, the present cement compositions may contain additional extraneous lime in amounts less than approximately 4.0 percent by weight of the pozzolan material. 
     EXAMPLES 
     Example 1 
     This example demonstrates the procedure for determining the requisite amount of fly ash to maximize the compressive strength of a cement composition. A number of different compositions were prepared employing various amounts of cement, and the amount of fly ash for each cement composition was varied. The 28-day compressive strength of each cement composition was measured and is reported in Table I. 
     The cement utilized in each of the tests consisted of a blend of equal portions by weight of three Type I Portland cements, as defined in ASTM Standard C 150-74, which were obtained from three different mills. This cement was utilized throughout the examples herein except as otherwise noted. 
     Unless otherwise noted, the sand utilized in each of the tests in this example and the other examples herein, consisted of a mixture of equal proportions of a relatively fine (No. 109) and a relatively coarse (No. 190) sand from Ottawa, Illinois. In tests G-1 pond screenings passing through a No. 200 mesh screen were utilized in addition to the Ottawa sand. In tests I-1 through I-5 the sand consisted of equal amounts of a commercially available sand known as Waugh sand from Montgomery, Ala., and a commercially available sand typical of those in Atlanta, Ga. 
     Unless otherwise noted, the pozzolan material utilized in each of the tests in this example and the other examples herein consisted of Bowen fly ash recovered from the combustion of pulverized bituminous coal at the Bowen Plant of the Georgia Power Company. In tests H-1 through H-3 and K-1 through K-3 a different pozzolan material was utilized comprising fly ash collected from the McDonough Plant of the same power company. 
     The mixing procedure utilized in each test was the basic procedure described in ASTM Standard C 109 with a few modifications. First the cement, fly ash, and water were added to the mixer described in the standard test procedure. The amount of cement utilized remained constant for a given series of tests, but the amount of water utilized in each test was adjusted to obtain relatively equal slumps (a measure of workability) for all tests within a given series of tests, e.g. tests A-1 through A-4. The cement, fly ash, and water were then mixed at the slow speed for 30 seconds, after which the sand or other fine aggregate was added to the mixer during a 30 second period while mixing at the slow speed. These ingredients were then mixed at the medium speed for an additional 30 seconds. The amount of sand added was adjusted to provide relatively equal volumes for all samples prepared. 
     The mixer was then turned off for 90 seconds, and during the first 15 seconds, the sides of the mixer were scraped down. The cement composition was then mixed at the medium speed for an additional 60 seconds. 
     During the first 90 seconds after the final mixing, the bowl was removed from the mixer. One-half of the mortar was removed and measured for slump, the test taking approximately 30 to 45 seconds to perform. If the slump varied from the slump of the other test samples within a given series of tests, the cement composition was reformulated to achieve approximately equivalent workability of all test compositions within the series of tests. The remaining half of the test sample was then tested by the procedure defined herein to determine the void content. Following completion of these tests, both fractions were returned to the mixing bowl and were mixed for fifteen seconds at the medium speed. The cement composition was compacted into six standard 2-inch cubes for measurement of compressive strength. The cubes were cured using lime water under ASTM Standard C 109 conditions. All tests were conducted under standard conditions of temperature and humidity specified in the same ASTM standard. 
     The slump was measured utilizing a measuring cone as described in paragraph 2.3 of ASTM Standard C 128-73. Initially one-half of the cone was filled with the test sample and rodded 25 times with a rounded tip rod having a diameter of 1/4&#34;. The remainder of the metalic cone was then filled and rodded 25 times with the rod passing through the top layer and barely into the second to consolidate the two layers. Following the second rodding, excess material was struck from the top of the cone utilizing the edge of a trowel, and the cone was slowly removed during a ten second interval. The cone was placed beside the conical mass of the test sample material, and the difference between the height of the standard cone (the original height of the sample) and the height of the sample after removal of the cone was then measured as the slump. 
     The volume of potential voids (water and entrained and entrapped air) was determined utilizing the following experimental procedure. A metallic cylinder, closed at one end and having a known volume and weight, was utilized to determine the density of each cement composition prepared. The cylinder was filled in three equal parts with subsequent rodding after each addition of the test sample as in the slump test. Following the rodding of the third layer, the excess test sample material was struck from the top and the density determined by dividing the volume of the cylinder by the difference in weight between the filled and unfilled cylinder. By knowing the total weight of the test sample material produced in a given test and the density, the total volume of the sample prepared could be computed. The difference between the total volume of the test sample and the total volume of the individual solid constituents in the test sample represents the void content of the sample. 
     The composition of the various test samples and the results of these tests are reported in Table I. These results indicate that for a given cement composition there is an optimum amount of pozzolan material which can be added to maximize the compressive strength of that composition. This maximum is reached when sufficient pozzolan material is added that the cement:pozzolan ratio is in the range of approximately 0.1 to 2.0. When more than the maximum amount of pozzolan material is added to the cement composition there is a commensurate decrease in the 28-day strength. The test results indicate that the 28-day strength of such pozzolan containing cement compositions is maximized when the void content of the composition is minimized as indicated by a paste:sand ratio between approximately 1.0 and 2.0. 
     
                                           TABLE I                                 
__________________________________________________________________________
                   Total Water                                            
                          Total              28 Day Cube                  
     Cement                                                               
          Pozzolan                                                        
               Sand                                                       
                   (cc/1000 cc                                            
                          Voids                                           
                              Paste/Sand                                  
                                    Cement/Pozzolan                       
                                             Strength                     
Example                                                                   
     (gms.)                                                               
          (gms.)                                                          
               (gms.)                                                     
                   composition)                                           
                          %   (vol.)                                      
                                    (vol.)   (psi)                        
__________________________________________________________________________
A-1  188  400  1352                                                       
                   231.4  26.35                                           
                              0.96  0.36     2790                         
A-2  188  500  1248                                                       
                   233.4  26.44                                           
                              1.12  0.29     2780                         
A-3  188  550  1183                                                       
                   239.4  27.06                                           
                              1.24  0.26     2740                         
A-4  188  600  1112                                                       
                   247.1  27.52                                           
                              1.38  0.24     2690                         
B-1  188  250  1489                                                       
                   247.7  27.64                                           
                              0.78  0.58     2510                         
B-2  188  350  1395                                                       
                   237.4  26.86                                           
                              0.90  0.42     2700                         
B-3  188  450  1293                                                       
                   235.3  26.82                                           
                              1.05  0.32     2880                         
B-4  188  550  1188                                                       
                   243.3  27.39                                           
                              1.23  0.26     2610                         
C-1  510.8                                                                
          --   1373                                                       
                   256.3  31.99                                           
                              0.93  --       --                           
C-2  704.7                                                                
          --   1227                                                       
                   267.4  31.24                                           
                              1.16  --       --                           
C-3  636.4                                                                
          --   1286                                                       
                   262.4  31.14                                           
                              1.06  --       --                           
C-4  701.1                                                                
          --   1221                                                       
                   271.0  31.59                                           
                              1.17  --       --                           
C-5  763  --   1173                                                       
                   276.2  31.58                                           
                              1.26  --       --                           
D-1  --   500  1472                                                       
                   204.7  23.95                                           
                              0.80  --       --                           
D-2  --   600  1366                                                       
                   207.7  23.80                                           
                              0.94  --       --                           
D-3  --   650  1312                                                       
                   209.3  24.11                                           
                              1.02  --       --                           
D-4  --   700  1256                                                       
                   212.8  24.09                                           
                              1.11  --       --                           
D-5  --   750  1132                                                       
                   222.0  24.88                                           
                              1.34  --       --                           
E-1  376  230  1352                                                       
                   247.2  27.69                                           
                              0.96  1.27     7940                         
E-2  376  290  1286                                                       
                   245.5  27.61                                           
                              1.06  1.00     7960                         
E-3  376  330  1244                                                       
                   248.1  27.57                                           
                              1.13  0.88     8190                         
E-4  376  400  1152                                                       
                   253.1  28.20                                           
                              1.30  0.73     7300                         
F-1  564   50  1352                                                       
                   261.9  28.83                                           
                              0.96  8.74     10,632                       
F-2  564  100  1305                                                       
                   261.7  29.07                                           
                              1.03  4.37     11,520                       
F-3  564  150  1250                                                       
                   264.6  29.22                                           
                              1.12  2.91     10,960                       
F-4  564  200  1188                                                       
                   266.4  29.31                                           
                              1.23  2.18     11,360                       
F-5  564  250  1113                                                       
                   271.2  29.98                                           
                              1.38  1.75     10,580                       
G-1  376  200* 1243                                                       
                   267.5  31.63                                           
                              1.06   1.53*   4050                         
G-2  376  250  1196                                                       
                   272.3  31.65                                           
                              1.14  1.22     4260                         
G-3  376  300  1138                                                       
                   275.7  32.09                                           
                              1.25  1.02     4600                         
H-1  188  200**                                                           
               1456                                                       
                   281.0  29.40                                           
                              0.82  0.62     1850                         
H-2  188  300  1345                                                       
                   273.5  28.98                                           
                              0.97  0.41     2060                         
H-3  188  400  1173                                                       
                   290.0  30.37                                           
                              1.26  0.31     1960                         
I-1  188  250  1380***                                                    
                   293.2  30.56                                           
                              0.89  0.58     1750                         
I-2  188  350  1312                                                       
                   271.0  29.10                                           
                              0.99  0.42     2000                         
I-3  188  450  1214                                                       
                   264.4  28.66                                           
                              1.15  0.32     2190                         
I-4  188  550  1125                                                       
                   265.4  28.73                                           
                              1.32  0.26     2180                         
I-5  188  600  1057                                                       
                   269.9  29.46                                           
                              1.47  0.24     2100                         
J-1  188  290****                                                         
               1380                                                       
                   260.3  28.38                                           
                              0.92  0.44     2430                         
J-2  188  390  1256                                                       
                   261.5  28.24                                           
                              1.11  0.32     2580                         
J-3  188  490  1118                                                       
                   269.4  29.30                                           
                              1.37  0.26     2430                         
K-1  376  160.5**                                                         
               1345                                                       
                   273.4  29.38                                           
                              0.97  1.54     5790                         
K-2  376  230  1256                                                       
                   278.0  29.50                                           
                              1.11  1.07     6210                         
K-3  376  300  1157                                                       
                   284.7  30.07                                           
                              1.29  0.82     6100                         
__________________________________________________________________________
 *Instead of a pozzolan material, the Gseries examples contained the      
 indicated amounts of pond screenings which passed through a 200 mesh     
 screen. The cement:pozzolan ratio for this series of tests is actually th
 cement:fines dry volume ratio.                                           
 **The pozzolan utilized in this sample consisted of fly ash from the     
 McDonough Plant of the Georgia Power Company.                            
 ***The sand utilized in this sample consisted of a 50:50 blend by weight 
 of commercially available sand known as Waugh sand from Montgomery,      
 Alabama and a commercially available sand typical of Atlanta, Georgia    
 sands.                                                                   
 ****The pozzolan utilized in this example consisted of New York fly ash  
 obtained from the Army Corps of Engineers.                               
 
    
     EXAMPLE 2 
     A series of tests were conducted illustrating the effect of including various ions in a pozzolan containing cement composition. The base composition or control utilized in these tests was as follows: 
     188 grams cement 
     500 grams fly ash 
     1250 grams sand 
     235 milliliters water 
     The cement:pozzolan ratio in this cement composition is 0.29, representing the optimum amount of fly ash for this composition as determined in examples A-1 through A-4 and B-1 through B-4 in Example 1. 
     The cement compositions in this example were prepared and tested as in Example 1 The water content of each test sample was adjusted in an attempt to prepare samples with equivalent workability within a given series of tests. The slump of each test sample was measured in sixteenths of an inch, and the compressive strength of the 2-inch cubes prepared from the various cement compositions was measured at the end of 7 and 28 days. 
     As noted in Table II various ionic materials in the amounts indicated were added in aqueous solution to the cement and pozzolan material at the beginning of the mixing procedure. The results of these tests are reported in Table II. Where tests were various ionic constituents were prepared on different days the results are compared to those of the base composition without ions prepared on the same day. The column at the extreme right in Table II indicates the ratio of the 28-day strength of the test sample to the 28-day strength of the control. 
     
                                           TABLE II                                
__________________________________________________________________________
    Total Water                    7-Day Cube                             
                                          28-Day Cube                     
                                                 28-Day Cube              
Test                                                                      
    (cc/1000 cc                                                           
           Slump        Chemical                                          
                             Paste/Sand                                   
                                   Strength                               
                                          Strength                        
                                                 Strength                 
Sample                                                                    
    composition)                                                          
           (16th&#34;)                                                        
               Chemical (grams)                                           
                             (vol.)                                       
                                   (psi)  (psi)  vs. Control              
__________________________________________________________________________
AA-1                                                                      
    233.8  10  --       --   1.13  1530   2890   1.00                     
AA-2                                                                      
    231.0  11  NaCl      8.9 1.13  2900   5290   1.83                     
AA-3                                                                      
    228.2  11  NaCl     17.9 1.13  3200   6250   2.16                     
AA-4                                                                      
    223.2  12  KCl      11.9 1.12  2780   4830   1.67                     
AA-5                                                                      
    218.5  12  KCl      23.9 1.12  3150   5900   2.04                     
AB-1                                                                      
    237.7  12  --       --   1.13  1540   2660   1.00                     
AB-2                                                                      
    235.6  14  Na.sub.2 SO.sub.4 . 10H.sub.2 O                            
                        25.9 1.34  2580   3790   1.42                     
AB-3                                                                      
    227.0  14  Na.sub.2 SO.sub.4 . 10H.sub.2 O                            
                        51.7 1.34  3690   5340   2.01                     
AB-4                                                                      
    228.9  14  NaNO.sub.2                                                 
                        11.1 1.12  2360   3810   1.43                     
AB-5                                                                      
    222.1  12  NaNO.sub.2                                                 
                        22.2 1.12  2560   4330   1.63                     
AC-1                                                                      
    230.9  12  --       --   1.14  1340   2950   1.00                     
AC-2                                                                      
    228.2  11  NaCl     10.6 1.12  2560   5650   1.92                     
AD-1                                                                      
    228.9    11.5                                                         
               --       --   1.11  1450   2890   1.00                     
AD-2                                                                      
    214.2   9  CaCl.sub.2                                                 
                        11.3 1.11  2030   3950   1.37                     
__________________________________________________________________________
 
    
     The results of these tests demonstrate that the use of the ions indicated improve both the 7-day and 28-day strengths of high pozzolan content cement compositions. However, over longer periods of time the advantages of using sodium sulfate by itself are doubtful. Test AD-2 also indicates that the early strength of high pozzolan cement compositions can be improved when calcium chloride is employed in the cement composition in the absence of an alkali metal ion. 
     EXAMPLE 3 
     Tests were conducted with cement compositions containing various amounts of sodium chloride. In tests BA-1 through BA-4, the base cement composition or control consisted of the following ingredients: 
     188 grams cement 
     250 grams fly ash 
     1475 grams sand 
     250 milliliters water The cement:pozzolan ratio of this cement composition is 0.58. 
     In tests BB-1 through BB-4, the base cement composition consisted of the following ingredients: 
     188 grams cement 
     550 grams ash 
     1222 grams sand 
     250 milliliters water The cement:pozzolan ratio of this cement composition is 0.27. 
     The remaining ingredients in the various test samples are set forth in Table III. These test samples were prepared and tested in accordance with the procedure set forth in Example 2, and the results are reported in Table III. These results indicate that the sodium and chloride ions increase the early compressive strength of high pozzolan content cement compositions. 
     
                                           TABLE III                               
__________________________________________________________________________
    Total Water                    7-Day Cube                             
                                          28-Day Cube                     
                                                 28-Day Cube              
Test                                                                      
    (cc/1000 cc                                                           
           Slump        Chemical                                          
                             Paste/Sand                                   
                                   Strength                               
                                          Strength                        
                                                 Strength                 
Sample                                                                    
    composition)                                                          
           (16th&#34;)                                                        
               Chemical (grams)                                           
                             (vol.)                                       
                                   (psi)  (psi)  vs. Control              
__________________________________________________________________________
BA-1                                                                      
    247.6  14  --       --   0.80  1150   2510   1.00                     
BA-2                                                                      
    248.3  15  NaCl      2.4 0.80  1440   2770   1.10                     
BA-3                                                                      
    241.7  15  NaCl      8.3 0.80  1950   3430   1.37                     
BA-4                                                                      
    231.8  14  NaCl     16.6 0.80  1940   4510   1.80                     
BB-1                                                                      
    243.3  14  --       --   1.23  1380   2610   1.00                     
BB-2                                                                      
    239.9  14  NaCl      5.2 1.23  2310   4610   1.77                     
BB-3                                                                      
    231.3  14  NaCl     18.2 1.22  3040   6890   2.64                     
BB-4                                                                      
    224.0  12  NaCl     36.6 1.22  3090   7580   2.90                     
__________________________________________________________________________
 
    
     EXAMPLE 4 
     A series of tests were conducted to demonstrate that the advantages of the present invention can be achieved utilizing different sands and different pozzolan materials. 
     In tests CA-1 and CA-2 the base cement composition or control consisted of the following ingredients: 
     188 grams cement 
     400 grams of Bowen fly ash 
     1260 grams of a 50/50 blend of commercially available sands comprising Waugh sand from Montgomery, Ala. and a commercially available sand typical of Atlanta, Ga. 
     276 milliliters water 
     The cement:pozzolan ratio of this cement composition is 0.36. 
     The base cement composition or control utilized in test samples CB-1 through CB-3 consisted of the following constituents: 
     188 grams cement 
     390 grams of a New York fly ash 
     1260 grams of a 50/50 blend of sands from Ottawa, Ill. 
     262 milliliters water 
     The cement:pozzolan ratio for this cement composition is 0.32. 
     Finally, tests CC-1 through CC-3 utilized the following control cement composition: 
     188 grams cement 
     444 grams of a Class N (natural) pozzolan obtained from the Oregon P.C. Co., Lime, Oreg. 
     1290 grams of a 50/50 blend of sands from Ottawa, Ill. 
     253 milliliters water 
     The cement:pozzolan ratio for this cement composition is 0.36. 
     
                                           TABLE IV                                
__________________________________________________________________________
    Total Water                7-Day Cube                                 
                                      28-Day Cube                         
                                             28-Day Cube                  
Test                                                                      
    (cc/1000 cc                                                           
           Slump    Chemical                                              
                         Paste/Sand                                       
                               Strength                                   
                                      Strength                            
                                             Strength                     
Sample                                                                    
    composition)                                                          
           (16th&#34;)                                                        
               Chemical                                                   
                    (grams)                                               
                         (vol.)                                           
                               (psi)  (psi)  vs. Control                  
__________________________________________________________________________
CA-1                                                                      
    276.9  19  --   --   1.07  1120   2190   1.00                         
CA-2                                                                      
    264.6  19  NaCl 13.3 1.07  2180   4500   2.06                         
CB-1                                                                      
    261.5  21  --   --   1.11  1430   2580   1.00                         
CB-2                                                                      
    249.6  18  NaCl 12.9 1.11  2410   4890   1.90                         
CB-3                                                                      
    244.2  20  NaCl 25.9 1.12  2420   5050   1.96                         
CC-1                                                                      
    250.5  14  --   --   1.08  1480   3140   1.00                         
CC-2                                                                      
    248.0  14  NaCl 13.3 1.10  2470   4230   1.35                         
CC-3                                                                      
    238.1  13  NaCl 26.6 1.09  2590   4640   1.48                         
__________________________________________________________________________
 
    
     The remaining ingredients in each of the test samples are set forth in Table IV. The test samples were prepared and tested in accordance with the procedure described in Example 2, and the results are reported in Table IV. These results indicate that the present invention is applicable to cement compositions containing various types of fly ash or other pozzolan material and fine aggregate. 
     EXAMPLE 5 
     To demonstrate the effect of varying the cement:pozzolan ratio and the proportion of ionic constituents included within the cement composition the following series of tests were performed. 
     In tests DA-1 through DA-5 the control cement composition consisted of the following ingredients: 
     376 grams cement 
     330 grams fly ash 
     1240 grams sand 
     250 milliliters water 
     The cement:pozzolan ratio for this composition is 0.88. 
     The base cement composition utilized in samples DB-1 through DB-6 consisted of the following: 
     376 grams cement 
     125 grams fly ash 
     1450 grams sand 
     254 milliliters water 
     The cement:pozzolan ratio of this sample composition is 2.33. 
     The following composition was utilized as the control cement composition in test samples DC-1 through DC-4: 
     564 grams cement 
     50 grams fly ash 
     1343 grams sand 
     260 milliliters water 
     The cement:pozzolan ratio for this sample is 8.74. 
     Finally, test samples DD-1 through DD-4 were prepared based on the following control composition: 
     564 grams cement 
     250 grams fly ash 
     1115 grams sand 
     270 milliliters water 
     This composition has a cement:pozzolan ratio of 1.75. 
     Again the test samples were prepared and tested according to the procedure described in Example 2. The results and the remaining constituents in each test sample are reported in Table V. 
     The results indicate that the advantages of the present invention were achieved in the DA series of tests wherein the ingredients were proportioned in accordance with the present invention. For the DB and DC series of tests significant increases in the early compressive strength were not realized, because of the relatively low proportion of fly ash in these tests as indicated by the cement:pozzolan ratios of 2.33 and 8.74 respectively for each series. In test series DD significant improvement in the compressive strength of the cement composition was not achieved because of the large amount of cement already in the cement composition. It has been found that the benefits of the present invention are achieved if the ratio of the solid volume of cement to the volume of mortar (cement, pozzolan, water, air, ionic constituents and sand) is less than about 0.19. 
     
                                           TABLE V                                 
__________________________________________________________________________
    Total Water                7-Day Cube                                 
                                      28-Day Cube                         
                                             28-Day Cube                  
Test                                                                      
    (cc/1000 cc                                                           
           Slump    Chemical                                              
                         Paste/Sand                                       
                               Strength                                   
                                      Strength                            
                                             Strength                     
Sample                                                                    
    composition)                                                          
           (16th&#34;)                                                        
               Chemical                                                   
                    (grams)                                               
                         (vol.)                                           
                               (psi)  (psi)  vs. Control                  
__________________________________________________________________________
DA-1                                                                      
    249.6  15  --   --   1.16  4630   7440   1.00                         
DA-2                                                                      
    250.1  13  NaCl 4.7  1.16  5130   8710   1.17                         
DA-3                                                                      
    244.3  13  NaCl 11.0 1.16  5900   9820   1.32                         
DA-4                                                                      
    238.9  15  NaCl 21.9 1.15  6030   10,540 1.42                         
DA-5                                                                      
    233.5  15  NaCl 31.4 1.15  5630   9720   1.31                         
DB-1                                                                      
    256.8  12  --   --   0.84  4450   6490   1.00                         
DB-2                                                                      
    256.5  15  NaCl 0.2  0.84  4590   6400   0.99                         
DB-3                                                                      
    251.9  12  NaCl 2.3  0.84  4970   6490   1.00                         
DB-4                                                                      
    249.6  11  NaCl 4.6  0.85  5090   6420   0.99                         
DB-5                                                                      
    241.3  12  NaCl 9.1  0.86  5420   7000   1.08                         
DB-6                                                                      
    232.8  11  NaCl 17.9 0.87  5230   7000   1.08                         
DC-1                                                                      
    263.2  14  --   --   0.98  9170   10,120 1.00                         
DC-2                                                                      
    256.8  14  NaCl 3.3  0.99  9500   10,270 1.02                         
DC-3                                                                      
    249.8  13  NaCl 9.5  1.00  9670   10,130 1.00                         
DC-4                                                                      
    245.1  13  NaCl 14.2 1.00  9170   10,000 0.99                         
DD-1                                                                      
    273.2  14  --   --   1.39  8420   11,000 1.00                         
DD-2                                                                      
    267.8  14  NaCl 3.3  1.39  8790   11,020 1.00                         
DD-3                                                                      
    265.1  14  NaCl 9.5  1.39  9290   11,690 1.06                         
DD-4                                                                      
    260.8  13  NaCl 14.3 1.39  9060   11,370 1.03                         
__________________________________________________________________________
 
    
     EXAMPLE 6 
     To demonstrate that the advantages of the present invention are achieved because of the interaction of the pozzolan material and the ionic constituents, cement compositions were prepared in which the pozzolan material was replaced by granite dust, an inert material with a fine particle size. The control cement composition utilized in these test samples (EA-1 through EA-5) comprised the following: 
     376 grams cement 
     250 grams of granite dust passing through a 200 mesh screen 
     1240 grams sand 
     270 milliliters water 
     The ratio of cement to fine granite dust on a dry volume basis is 1.22. 
     The procedure described in Example 2 was followed in the preparation and testing of the test samples. The remaining constituents in each test sample and the results of the tests are reported in Table VI. These test results indicate that the presence of ionic constituents which are effective in increasing the early strength of high pozzolan cement compositions are ineffective for the same purpose in cement compositions including a high content of fine inert material. 
     EXAMPLE 7 
     A series of tests were conducted to demonstrate that the present invention is applicable to cement compositions containing different types of Portland cement. 
     
                                           TABLE VI                                
__________________________________________________________________________
    Total Water                7-Day Cube                                 
                                      28-Day Cube                         
                                             28-Day Cube                  
Test                                                                      
    (cc/1000 cc                                                           
           Slump    Chemical                                              
                         Paste/Sand                                       
                               Strength                                   
                                      Strength                            
                                             Strength                     
Sample                                                                    
    composition)                                                          
           (16th&#34;)                                                        
               Chemical                                                   
                    (grams)                                               
                         (vol.)                                           
                               (psi)  (psi)  vs. Control                  
__________________________________________________________________________
EA-1                                                                      
    270.4  16  --   --   1.14  3230   4600   1.00                         
EA-2                                                                      
    264.4  15  NaCl 3.6  1.14  3520   4540   0.987                        
EA-3                                                                      
    261.7  14  NaCl 8.0  1.14  3830   4640   1.009                        
EA-4                                                                      
    261.0  20  NaCl 16.6 1.14  3590   4490   0.976                        
EA-5                                                                      
    252.3  16  NaCl 23.8 1.16  3470   4500   0.978                        
__________________________________________________________________________
 
    
     
                                           TABLE VII                               
__________________________________________________________________________
    Total Water                7-Day Cube                                 
                                      28-Day Cube                         
                                             28-Day Cube                  
Test                                                                      
    (cc/1000 cc                                                           
           Slump    Chemical                                              
                         Paste/Sand                                       
                               Strength                                   
                                      Strength                            
                                             Strength                     
Sample                                                                    
    composition)                                                          
           (16th&#34;)                                                        
               Chemical                                                   
                    (grams)                                               
                         (vol.)                                           
                               (psi)  (psi)  vs. Control                  
__________________________________________________________________________
FA-1                                                                      
    232.5  15  --   --   1.12   930   1790   1.00                         
FA-2                                                                      
    220.0  15  NaCl 16.6 1.11  2550   5040   2.82                         
FA-3                                                                      
    213.8  14  NaCl 33.3 1.12  2270   5640   3.15                         
FB-1                                                                      
    238.4  14  --   --   1.13  1750   2930   1.00                         
FB-2                                                                      
    232.8  14  NaCl 16.6 1.15  3430   6360   2.17                         
FB-3                                                                      
    226.9  15  NaCl 33.3 1.14  3330   6940   2.37                         
__________________________________________________________________________
 
    
     In test samples FA-1 through FA-3 the control cement composition contained the following ingredients: 
     188 grams of a Type II Portland cement 
     500 grams fly ash 
     1250 grams sand 
     253 milliliters of water 
     In test FB-1 through FB-3 the same control composition was utilized except that the cement utilized was a Type III Portland cement. The cement:pozzolan ratio in each of the control samples for the FA and FB Series of tests is 0.29. 
     Again the test samples were prepared and tested according to the procedure described in Example 2. The remaining constituents in each test sample and the results of the tests are reported in Table VII. The tests demonstrate that excellent results are achieved with the cement compositions of the present invention regardless of the type of cement which is utilized. 
     EXAMPLE 8 
     The purpose of this series of tests was to demonstrate that the present invention is applicable to cement compositions, such as those employed in manufacturing prefabricated structural elements, which are subjected to thermal treatment or autoclaving to accelerate the curing rate. The compositions of the test samples are indicated in Table VIII. Unless otherwise indicated the samples utilized a blend of three Type I Portland cements, Bowen fly ash, and a 50/50 blend of fine and coarse sands from Ottawa, Illinois as the major constituents as previously described in Example 1. The test procedure described in Example 2 was followed, except that the cubes formed from the various test samples were maintained in the laboratory for 24 hours at atmospheric conditions and then cured for 17 hours at a minimum temperature of 167 degrees Fahrenheit in water. The compressive strength of the cubes was then measured and the results are reported in Table VIII. 
     
                                           TABLE VIII                              
__________________________________________________________________________
    C.-          Total Water                Cement/                       
                                                 Compressive              
                                                        Compressive       
Test                                                                      
    ment                                                                  
        Pozzolan                                                          
             Sand                                                         
                 (cc/1000 cc     Chemical                                 
                                      Paste/Sand                          
                                            Pozzolan                      
                                                 Strength                 
                                                        Strength          
Sample                                                                    
    (gms.)                                                                
        (cc.)                                                             
             (gms.)                                                       
                 composition)                                             
                        Chemical (gms.)                                   
                                      (vol.)                              
                                            (vol.)                        
                                                 (psi)  vs.               
__________________________________________________________________________
                                                        Control           
GA-1                                                                      
    188 102.46                                                            
             1475                                                         
                 248    --       --   0.79  0.58 2900   1.00              
GA-2                                                                      
    188 102.46                                                            
             1475                                                         
                 232    NaCl     16.6 0.79  0.58 4500   1.55              
GB-1                                                                      
    188 225.41                                                            
             1222                                                         
                 243    --       --   1.23  0.27 4180   1.00              
GB-2                                                                      
    188 225.41                                                            
             1222                                                         
                 222    NaCl     36.6 1.24  0.27 8310   1.99              
GC-1                                                                      
    376 135.24                                                            
             1240                                                         
                 250    --       --   1.16  0.88 6580   1.00              
GC-2                                                                      
    376 135.24                                                            
             1240                                                         
                 239    NaCl     21.9 1.15  0.88 10,310 1.57              
GD-1                                                                      
    188*                                                                  
        204.92                                                            
             1250                                                         
                 233    --       --   1.12  0.29 3250   1.00              
GD-2                                                                      
    188 204.92                                                            
             1250                                                         
                 221    NaCl     16.6 1.11  0.29 6050   1.86              
GE-1                                                                      
    188**                                                                 
        204.92                                                            
             1250                                                         
                 238    --       --   1.13  0.29 5100   1.00              
GE-2                                                                      
    188 204.92                                                            
             1250                                                         
                 227    NaCl     16.6 1.15  0.29 7150   1.40              
GF-1                                                                      
    188 163.84***                                                         
             1290                                                         
                 251    --       --   1.07  0.36 3950   1.00              
GF-2                                                                      
    188 163.84                                                            
             1290                                                         
                 238    NaCl     29.5 1.07  0.36 6050   1.53              
GG-1                                                                      
    188 204.92                                                            
             1250                                                         
                 234    --       --   1.13  0.29 3930   1.00              
GG-2                                                                      
    188 204.92                                                            
             1250                                                         
                 229    NaCl     17.8 1.13  0.29 7330   1.87              
GG-3                                                                      
    188 204.92                                                            
             1250                                                         
                 215    KCl      23.9 1.13  0.29 6450   1.64              
GH-1                                                                      
    188 204.92                                                            
             1250                                                         
                 238    --       --   1.13  0.29 4130   1.00              
GH-2                                                                      
    188 204.92                                                            
             1250                                                         
                 198    Na.sub.2 SO.sub.4 . 10H.sub.2 O                   
                                 51.7 1.14  0.29 4780   1.16              
GH-3                                                                      
    188 204.92                                                            
             1250                                                         
                 222    NaNO.sub.2                                        
                                 22.2 1.14  0.29 6200   1.50              
GI-1                                                                      
    188 204.92                                                            
             1250                                                         
                 231    NaCl     10.7 1.13  0.29 6180   --                
GI-2                                                                      
    188 204.92                                                            
             1250                                                         
                 229    CaCl.sub.2                                        
                                 11.3 1.13  0.29 6230   --                
__________________________________________________________________________
 *In samples GD1 and GD2 a Type II Portland cement was utilized.          
 **In samples GE1 and GE2 a Type III Portland cement was utilized.        
 ***The pozzolan material utilized in samples GF1 and GF2 was a natural   
 pozzolan obtained from Oregon P.C. Co.                                   
 
    
     
                                           TABLE IX                                
__________________________________________________________________________
                               Paste/                                     
                                    Cement/                               
                                         7-Day Cube                       
                                                 28-Day                   
                                                        28-Day Cube       
Test                                                                      
    Cement                                                                
          Pozzolan                                                        
               Sand       Water                                           
                               Sand Pozzolan                              
                                         Strength                         
                                                 Strength                 
                                                        Strength          
Sample                                                                    
    (gms.)                                                                
          (cc.)                                                           
               (gms)                                                      
                   Water Type                                             
                          Amount                                          
                               (vol.)                                     
                                    (vol.)                                
                                         (psi)   (psi)  vs.               
__________________________________________________________________________
                                                        Control           
HA-1                                                                      
    188   102.46                                                          
               1475                                                       
                   City   248  0.79 0.58 1150    2510   1.00              
HA-2                                                                      
    188   102.46                                                          
               1475                                                       
                   Sea Water                                              
                          240  0.79 0.58 1790    3940   1.57              
HB-1                                                                      
    188   143.44                                                          
               1380                                                       
                   City   237  0.90 0.42 1400    2700   1.00              
HB-2                                                                      
    188   143.44                                                          
               1380                                                       
                   Sea Water                                              
                          230  0.89 0.42 2350    5130   1.90              
HC-1                                                                      
    188   184.43                                                          
               1380                                                       
                   City   235  1.05 0.32 1520    2880   1.00              
HC-2                                                                      
    188   184.43                                                          
               1380                                                       
                   Sea Water                                              
                          235  0.92 0.32 2580    5530   1.92              
HD-1                                                                      
    188   183.96*                                                         
               1260                                                       
                   City   261  1.11 0.32 1430    2580   1.00              
HD-2                                                                      
    188   183.96                                                          
               1260                                                       
                   Sea Water                                              
                          255  1.11 0.32 2230    4090   1.59              
HE-1                                                                      
    188   163.84**                                                        
               1290                                                       
                   City   251  1.08 0.36 1480    3140   1.00              
HE-2                                                                      
    188   163.84                                                          
               1290                                                       
                   Sea Water                                              
                          252  1.08 0.36 2550    4200   1.34              
HF-1                                                                      
    188***                                                                
          204.92                                                          
               1250                                                       
                   City   233  1.12 0.29  930    1790   1.00              
HF-2                                                                      
    188   204.92                                                          
               1250                                                       
                   Sea Water                                              
                          235  1.12 0.29 1750    3860   2.16              
HG-1                                                                      
    188****                                                               
          204.92                                                          
               1250                                                       
                   City   238  1.13 0.29 1750    2930   1.00              
HG-2                                                                      
    188   204.92                                                          
               1250                                                       
                   Sea Water                                              
                          227  1.13 0.29 2870    5090   1.74              
HH-1                                                                      
    564   --   1400                                                       
                   City   260  0.93 --   7530    9960   1.00              
HH-2                                                                      
    564   --   1400                                                       
                   Sea Water                                              
                          251  0.95 --   7940    9840   0.99              
HH-3                                                                      
    564    20.49                                                          
               1343                                                       
                   Sea Water                                              
                          257  0.99 8.74 8690    10,520 1.06              
HH-4                                                                      
    564    61.48                                                          
               1240                                                       
                   Sea Water                                              
                          256  1.14 2.91 9500    11,330 1.14              
HH-5                                                                      
    564   102.46                                                          
               1115                                                       
                   Sea Water                                              
                          268  1.40 1.75 8530    11,500 1.16              
__________________________________________________________________________
 *The pozzolan material utilized in samples HD1 and HD2 was a New York fly
 ash.                                                                     
 **The pozzolan material utilized in samples HE1 and HE2 was a natural    
 pozzolan obtained from Oregon P.C. Co.                                   
 ***In samples HF1 and HF2 a Type II Portland cement was utilized.        
 ****In samples HG1 and HG2 a Type III Portland cement was utilized.      
 
    
     The test results indicate that the present invention can be applied to cement compositions which are subjected to accelerated curing by heating. Again the presence of the ionic constituents improved the early compressive strength characteristics of these cement compositions. 
     EXAMPLE 9 
     Tests were performed to demonstrate that the advantages of the present invention are achieved when the ions are supplied in the form of sea water. The composition of the test samples is recorded in Table IX. Unless otherwise noted all samples utilized a blend of three Type I Portland cements, Bowen fly ash, and a 50/50 blend of fine and coarse sands from Ottawa, Illinois. The test samples were prepared and tested according to the procedure outlined in Example 2. The test results are reported in Table IX. 
     The test results indicate that the use of sea water in a high pozzolan content cement composition significantly increases the early strength of the product. 
     EXAMPLE 10 
     To demonstrate the economic advantages of the present invention a series of tests were performed comparing the relative cost of typical commercially available cement compositions not containing pozzolan material (tests IA-1 through IA-5), cement compositions containing pozzolan material as presently used in the industry (test samples IB-1 through IB-4), cement compositions containing a large proportion of pozzolan (test samples IC-1 through IC-4), and cement compositions containing a large proportion of pozzolan and sodium chloride in an amount equal to 6.65 wt percent of the pozzolan material (test samples ID-1 through ID-8). The test compositions employed cement comprising a blend of three Type I Portland cements, Bowen fly ash, and a 50/50 mixture of fine and coarse sands from Ottawa, Illinois. 
     The composition of these test samples is reported in Table X. Test samples were prepared and tested in accordance with the procedure set forth in Example 2, and the results of those tests are also reported in Table X. The cost of the cementitious material per yard of concrete was based on a cement cost of $1.80 per 100 pounds and a pozzolan cost of $0.50 per 100 pounds. 
     FIG. 1 is a graph of these test results for the IA, IB, and ID series of tests, indicating the relationship between the amount of cement in a cement composition versus the 28-day strength of that composition. The graph indicates that for a given amount of cement the strength can be improved by adding pozzolan up to the normal amount used in commercially available cement compositions. However, as indicated by the IC series of tests, the early strength of the cement composition decreases if additional pozzolan is added without utilizing ionic constituents as employed in the present invention. Thus, any economic advantage associated with the use of pozzolan material in excess of the normal amount is offset by a decrease in structural properties. 
     
                                           TABLE X                                 
__________________________________________________________________________
    Net           Net         Paste/                                      
                                  Cement/                                 
                                       7-Day Cube                         
                                              28-Day Cube                 
Test                                                                      
    Cement                                                                
         Pozzolan                                                         
              Sand                                                        
                  Water                                                   
                      Net Slump                                           
                              Sand                                        
                                  Pozzolan                                
                                       Strength                           
                                              Strength                    
                                                     Cost                 
Sample                                                                    
    (gms.)                                                                
         (gms.)                                                           
              (gms.)                                                      
                  (cc)                                                    
                      Voids                                               
                          (16th&#34;)                                         
                              (vol.)                                      
                                  (vol.)                                  
                                       (psi)  (psi)  ($)                  
__________________________________________________________________________
IA-1                                                                      
    289.5                                                                 
         --   1380                                                        
                  336.7                                                   
                      365.3                                               
                          14  0.84                                        
                                  --   1300   1890   5.21                 
IA-2                                                                      
    462.7                                                                 
         --   1380                                                        
                  300.3                                                   
                      332.6                                               
                          12  0.92                                        
                                  --   4580   6960   8.33                 
IA-3                                                                      
    643.9                                                                 
         --   1260                                                        
                  292.6                                                   
                      323.2                                               
                          12  1.12                                        
                                  --   9000   11,790 11.59                
IA-4                                                                      
    842.7                                                                 
         --   1030                                                        
                  311.8                                                   
                      339.4                                               
                          12  1.54                                        
                                  --   11,250 14,080 15.17                
IA-5                                                                      
    1033.6                                                                
         --    800                                                        
                  339.9                                                   
                      365.5                                               
                          14  2.26                                        
                                  --   12,500 15,120 18.60                
IB-1                                                                      
    285.0                                                                 
         126.3                                                            
              1400                                                        
                  303.2                                                   
                      315.6                                               
                          13  0.84                                        
                                  1.75 1900   3240   5.76                 
IB-2                                                                      
    472.7                                                                 
         125.7                                                            
              1280                                                        
                  291.7                                                   
                      305.2                                               
                          15  1.03                                        
                                  2.91 6000   8820   9.14                 
IB-3                                                                      
    664.8                                                                 
         126.3                                                            
              1090                                                        
                  303.1                                                   
                      315.3                                               
                          14  1.37                                        
                                  4.08 9250   12,000 12.60                
IB-4                                                                      
    844.1                                                                 
         124.7                                                            
               880                                                        
                  324.3                                                   
                      344.5                                               
                          15  1.97                                        
                                  5.24 11,250 13,820 15.81                
IC-1                                                                      
     92.0                                                                 
         645.8                                                            
              1140                                                        
                  255.4                                                   
                      278.7                                               
                          13  1.34                                        
                                  0.11 500    850    4.89                 
IC-2                                                                      
    276.9                                                                 
         471.3                                                            
              1140                                                        
                  272.0                                                   
                      290.1                                               
                          15  1.33                                        
                                  0.46 2450   4140   7.34                 
IC-3                                                                      
    468.6                                                                 
         279.2                                                            
              1140                                                        
                  286.1                                                   
                      301.4                                               
                          14  1.30                                        
                                  1.30 6100   8940   9.83                 
IC-4                                                                      
    667.2                                                                 
          81.1                                                            
              1140                                                        
                  291.0                                                   
                      312.0                                               
                          15  1.26                                        
                                  6.37 9500   12,030 12.42                
ID-1                                                                      
     92.7                                                                 
         651.1                                                            
              1140                                                        
                  235.8                                                   
                      272.5                                               
                          14  1.32                                        
                                  0.11 1380   3200   4.93                 
ID-2                                                                      
    277.4                                                                 
         472.2                                                            
              1140                                                        
                  246.9                                                   
                      288.7                                               
                          16  1.33                                        
                                  0.46 4150   8130   7.35                 
ID-3                                                                      
    469.2                                                                 
         279.6                                                            
              1140                                                        
                  268.6                                                   
                      300.4                                               
                          13  1.29                                        
                                  1.23 7500   10,370 9.85                 
ID-4                                                                      
    664.5                                                                 
          80.8                                                            
              1140                                                        
                  285.8                                                   
                      314.8                                               
                          13  1.27                                        
                                  6.37 9750   11,630 12.36                
ID-5                                                                      
    275.1                                                                 
         501.4                                                            
              1100                                                        
                  259.0                                                   
                      296.1                                               
                          14  1.43                                        
                                  0.42 4130   8000   7.46                 
ID-6                                                                      
    468.6                                                                 
         367.9                                                            
              1020                                                        
                  278.2                                                   
                      310.8                                               
                          15  1.57                                        
                                  0.99 6700   10,880 10.27                
ID-7                                                                      
    670.1                                                                 
         227.1                                                            
               950                                                        
                  298.0                                                   
                      323.5                                               
                          13  1.70                                        
                                  2.29 9500   12,130 13.20                
ID-8                                                                      
    868.3                                                                 
          80.0                                                            
               880                                                        
                  321.3                                                   
                      345.5                                               
                          15  1.89                                        
                                  8.41 11,250 13,380 16.03                
__________________________________________________________________________
 
    
     As indicated by FIG. 1, significant economic advantages are achieved when excess pozzolan material is utilized in conjunction with the proper amounts of ions which accelerate the pozzolanic reaction. Cement compositions prepared in accordance with the present invention are significantly less expensive per unit volume than commercially available cement compositions having equivalent compressive strengths. 
     The line representing cement compositions of the present invention intersects the line corresponding to normal pozzolan cement compositions at the point where the ratio of the solid volume of cement to the volume of mortar is about 0.19. 
     EXAMPLE 11 
     Tests were performed to demonstrate the efficacy of utilizing potassium bromide as the source of the ionic constituents in cement compositions of the present invention. The control cement composition utilized in each of the tests JA-1 through JA-3 is as follows: 
     188 grams Type I cement 
     550 grams fly ash 
     1170 grams Waugh sand 
     247 milliliters water 
     Each of the samples utilized in this series of tests has a cement:pozzolan ratio of 0.26 and a paste:sand ratio of 1.26. 
     As indicated in Table XI, sample JA-1 contained 22.0 grams of sodium chloride or approximately 4 percent by weight of the fly ash. Otherwise stated, sample JA-1 contained 1.6 percent sodium ions and 2.4 percent chlorine ions by weight of the fly ash present. In sample JA-2 and JA-3 sufficient amounts of potassium bromide and potassium iodide were added respectively to supply ions in an equivalent weight of the sodium and chloride ions present in sample JA-1. 
     
                                           TABLE XI                                
__________________________________________________________________________
    Total Water                7-Day Cube                                 
                                      33-Day Cube                         
Test                                                                      
    (cc/1000 cc                                                           
           Slump    Chemical                                              
                         Paste/Sand                                       
                               Strength                                   
                                      Strength                            
Sample                                                                    
    composition)                                                          
           (16th&#34;)                                                        
               Chemical                                                   
                    (grams)                                               
                         (vol.)                                           
                               (psi)  (psi)                               
__________________________________________________________________________
JA-1                                                                      
    241    18  NaCl 22.0 1.26  3550   7200                                
JA-2                                                                      
    234    16  KBr  44.7 1.26  3650   7250                                
JA-3                                                                      
    232    16  KI   62.4 1.26  2500   4600                                
__________________________________________________________________________
 
    
     The test procedures previously identified were followed with respect to samples JA-1 through JA-3 with the exception that the compressive strength was measured at the end of 33 rather than 28 days. The results are reported in Table XI. These results indicate that cement compositions of the present invention employing potassium bromide demonstrate strength characteristics at least as good as, if not better than, those employing sodium chloride. However, the same degree of strength improvement was not achieved when potassium iodide was utilized. 
     EXAMPLE 12 
     Tests were performed to demonstrate the efficacy of utilizing various ions in cement compositions of the present invention. The base cement composition utilized in each of the test series KA, KB, KC, KE, and KF is as follows: 
     188 grams Type I cement 
     500 grams Bowen fly ash 
     1250 grams of a 50/50 blend of sands from Ottawa, Ill. 
     247 milliliters water 
     Each of the samples utilized in these series of tests has a cement:pozzolan ratio of 0.29 and a paste:sand ratio in the amount indicated in Table XII. 
     The base cement composition utilized in each of the test series KD and KG is as follows: 
     188 grams Type I cement 
     450 grams Bowen fly ash 
     1260 grams Shorter, a commercially available sand from Shorter, Ala. 
     247 milliliters water. 
     Each of these samples had a cement:pozzolan ratio of 0.32 and a paste:sand ratio as indicated in Table XII. Each of the samples contained ionic constituents of the type and amount indicated in Table XII. 
     The test procedures previously identified in Example 2 were followed with respect to samples KA through KG. In addition, identical samples were prepared and subjected to accelerated curing conditions as described in Example 8. 
     The test results are reported in Table XII. 
     
                                           TABLE XII                               
__________________________________________________________________________
    Total Water                    7-Day Cube                             
                                          28-Day Cube                     
                                                 Accelerated              
Test                                                                      
    (cc/1000 cc                                                           
           Slump        Chemical                                          
                             Paste/Sand                                   
                                   Strength                               
                                          Strength                        
                                                 Cube Strength            
Sample                                                                    
    composition)                                                          
           (16th&#34;)                                                        
               Chemical (grams)                                           
                             (Vol.)                                       
                                   (psi)  (psi)  (psi)                    
__________________________________________________________________________
KA-1                                                                      
    231.9  14  --       --   1.12  2200   3630   4130                     
KA-2                                                                      
    220.1  16  NaCl     20.0 1.12  3930   6900   6720                     
KA-3                                                                      
    231.1  12  NaSCN     6.5 1.12  2500   4500   5950                     
KA-4                                                                      
    223.4  16  Na.sub.2 S.sub.2 O.sub.3                                   
                         9.6 1.12  3300   5170   4800                     
KA-5                                                                      
    225.4  15  NaSCN, Na.sub.2 S.sub.2 O.sub.3                            
                        6.5, 3.2                                          
                             1.12  2900   5450   6240                     
KA-6                                                                      
    222.2  15  NaSCN, Na.sub.2 S.sub.2 O.sub.3                            
                        6.5, 6.4                                          
                             1.12  3800   6090   6900                     
KA-7                                                                      
    224.6  15  NaSCN, Na.sub.2 S.sub.2 O.sub.3                            
                        6.5, 9.6                                          
                             1.12  4100   7090   6880                     
KA-8                                                                      
    224.2  16  NaSCN, Na.sub.2 S.sub.2 O.sub.3                            
                        6.5, 12.7                                         
                             1.12  4250   7320   7220                     
KA-9                                                                      
    219.4  17  NaSCN, Na.sub.2 S.sub.2 O.sub.3                            
                        6.5, 15.9                                         
                             1.13  4350   7660   7480                     
KB-1                                                                      
    221.2  16  NaCl     20.0 1.12  3550   6940   7220                     
KB-2                                                                      
    223.2  15  Na.sub.2 S.sub.2 O.sub.3                                   
                        12.7 1.12  3530   5650   5150                     
KB-3                                                                      
    222.6  14  NaSCN, Na.sub.2 S.sub.2 O.sub.3                            
                        2.5, 12.7                                         
                             1.13  4100   6930   7040                     
KB-4                                                                      
    222.6  17  NaSCN, Na.sub.2 S.sub.2 O.sub.3                            
                        5.0, 12.7                                         
                             1.13  4150   7160   6900                     
KB-5                                                                      
    219.6  15  NaSCN, Na.sub.2 S.sub.2 O.sub.3                            
                        7.5, 12.7                                         
                             1.13  3930   7650   7570                     
KB-6                                                                      
    220.6  15  NaSCN, Na.sub.2 S.sub.2 O.sub.3                            
                        10.0, 12.7                                        
                             1.13  4200   7720   7630                     
KB-7                                                                      
    220.3  16  NaSCN, Na.sub.2 S.sub.2 O.sub.3                            
                        12.5, 12.7                                        
                             1.13  4200   7880   7380                     
KB-8                                                                      
    217.8  18  NaSCN, Na.sub.2 S.sub.2 O.sub.3                            
                        15.0, 12.7                                        
                             1.13  4250   8090   7690                     
KB-9                                                                      
    218.3  17  NaSCN, Na.sub.2 S hd 2O.sub. 3                             
                        17.5, 12.7                                        
                             1.13  4250   8000   7850                     
KB-10                                                                     
    215.2  15  NaSCN, Na.sub.2 S.sub.2 O.sub.3                            
                        26.0, 12.7                                        
                             1.13  4030   8380   8130                     
KC-1                                                                      
    217.0  16  NaCl     20.0 1.08  3700   6550   7650                     
KC-2                                                                      
    216.4  12  KCN, Na.sub.2 S.sub.2 O.sub.3                              
                        5.6, 9.6                                          
                             1.11  4600   7100   7790                     
KC-3                                                                      
    219.2  16  NaSCN, Na.sub.2 S.sub.2 O.sub.3                            
                        7.5, 9.6                                          
                             1.10  3750   6350   7550                     
KD-1                                                                      
    248.9  18  NaCl     18.0 1.09   2500* 5100   6850                     
KD-2                                                                      
    250.4  17  NaSCN    12.5 1.08   2100* 3900   6600                     
KD-3                                                                      
    242.1  18  NaSCN    25.0 1.07   2550* 4500   6930                     
KE-1                                                                      
    230.1  17  NaCl     20.0 1.10  2900   6270   7070                     
KE-2                                                                      
    228.5  17  NaNO.sub.3                                                 
                        10.0 1.10  2150   3930   4230                     
KE-3                                                                      
    227.0  14  KC.sub.3 H.sub.5 O.sub.3                                   
                        1.37 1.10  2280   4420   5100                     
               NaNO.sub.3                                                 
                        10.0                                              
KE-4                                                                      
    228.1  18  KC.sub.3 H.sub.5 O.sub.3                                   
                        2.74 1.10  2400   4700   5840                     
               NaNO.sub.3                                                 
                        10.0                                              
KE-5                                                                      
    228.4  17  KC.sub.3 H.sub.5 O.sub.3                                   
                        4.11 1.10  2530   4840   6300                     
               NaNO.sub.3                                                 
                        10.0                                              
KE-6                                                                      
    224.0  15  KC.sub.3 H.sub.5 O.sub.3                                   
                        5.48 1.09  2800   4940   6850                     
               NaNO.sub.3                                                 
                        10.0                                              
KE-7                                                                      
    227.5  15  KC.sub.3 H.sub.5 O.sub.3                                   
                        6.85 1.09  3030   5430   7250                     
               NaNO.sub.3                                                 
                        10.0                                              
KE-8                                                                      
    232.7  16  KC.sub.3 H.sub.5 O.sub.3                                   
                        5.48 1.10  2600   4150   6450                     
KE-9                                                                      
    224.3  14  KC.sub.3 H.sub.5 O.sub.3                                   
                        5.48 1.09  2700   4730   6920                     
               NaNO.sub.3                                                 
                        5.0                                               
KE-10                                                                     
    220.5  15  KC.sub.3 H.sub.5 O.sub.3                                   
                        5.48                                              
               NaNO.sub.3                                                 
                        15.0 1.09  2900   5450   6570                     
KF-1                                                                      
    234.5  14  --       --   1.11  2000   3350   4500                     
KF-2                                                                      
    227.2  15  NaCl     10   1.10  3150   5700   6430                     
KF3 227.0  20  NaCl     20   1.10  3070   6450   6900                     
KF-4                                                                      
    222.9  14  KC.sub.3 H.sub.5 O.sub.3                                   
                        6.85 1.09  3180   5400   6850                     
               NaNO.sub.3                                                 
                        10.0                                              
KF-5                                                                      
    230.0  17  LiCl     7.25 1.10  3050   5600   6550                     
KF-6                                                                      
    224.2  16  LiCl     14.50                                             
                             1.10  3250   6900   7130                     
KF-7                                                                      
    228.2  18  KCl      12.73                                             
                             1.10  3150   5450   6150                     
KF-8                                                                      
    223.0  17  KCl      25.47                                             
                             1.10  3150   5750   6400                     
KG-1                                                                      
    243.0  16  NaCl     18.0 1.06  2700   5280   6970                     
KG-2                                                                      
    240.2  16  KCN      20.0 1.06  3250   5480   7320                     
__________________________________________________________________________
  *Measured at the end of 5 rather than 7 days.                           
 
    
     EXAMPLE 13 
     Tests were performed to demonstrate the efficacy of utilizing various combinations of anions in cement compositions of the present invention. The base cement compositions utilized in each of the test series LA and LB is as follows: 
     188 grams Type I cement 
     500 grams Bowen fly ash 
     1250 grams of a 50/50 mixture of sands from Ottawa, Ill. 
     247 milliliters water 
     Each of the samples utilized in these series of tests had a cement:pozzolan ratio of 0.29 and a paste:sand ratio as indicated in Table XIII. 
     The base cement composition utilized in the LC series of tests is as follows: 
     213 grams Type I cement 
     500 grams Bowen fly ash 
     1230 grams of a 50/50 mixture of sands from Ottawa, Ill. 
     247 milliliters water 
     Each of the samples utilized in the LC series of tests had a cement:pozzolan ratio of 0.33 and a paste:sand ratio as indicated in Table XIII. Each of the samples contained ionic constituents of the type and amount indicated in Table XIII. 
     The test procedures previously identified in Example 2 were followed with respect to test samples LA through LC. In addition identical samples were prepared and subjected to accelerated curing conditions as described in Example 8. 
     The test results are reported in Table XIII. These results indicate that various combinations of ions may be used in the cement compositions of the present invention. 
     
                                           TABLE XIII                              
__________________________________________________________________________
    Total Water                 7-Day Cube                                
                                       28-Day Cube                        
                                              Accelerated                 
Test                                                                      
    (cc/1000 cc                                                           
           Slump     Chemical                                             
                          Paste/Sand                                      
                                Strength                                  
                                       Strength                           
                                              Cube Strength               
Sample                                                                    
    composition)                                                          
           (16th&#34;)                                                        
               Chemical                                                   
                     (grams)                                              
                          (Vol.)                                          
                                (psi)  (psi)  (psi)                       
__________________________________________________________________________
LA-1                                                                      
    225.0  17  NaCl  20.0 1.09  3350   6340   7230                        
LA-2                                                                      
    233.1  16  NaSCN 6.5  1.09  2330   4300   5980                        
LA-3                                                                      
    230.3  16  Na.sub.2 SO.sub.4                                          
                     10.0 1.09  2850   4580   3750                        
LA-4                                                                      
    224.5  14  NaSCN 6.5  1.09  3630   6070   6080                        
               Na.sub.2 SO.sub.4                                          
                     10.0                                                 
LA-5                                                                      
    219.6  18  NaSCN 6.5  1.07  4380   7470   7050                        
               Na.sub.2 SO.sub.3                                          
                     2.0                                                  
               Na.sub.2 SO.sub.4                                          
                     10.0                                                 
LA-6                                                                      
    216.7  18  NaSCN 6.5  1.07  4830   7630   6650                        
               Na.sub.2 SO.sub.4                                          
                     10.0                                                 
               Na.sub.2 SO.sub.3                                          
                     4.0                                                  
LB-1                                                                      
    223.9  16  NaCl  20.0 1.09  3400   6830   6800                        
LB-2                                                                      
    217.6  16  NaNO.sub.3                                                 
                     10.0 1.07  3500   5700   5280                        
               Na.sub.2 S.sub.2 O.sub.3                                   
                     9.6                                                  
LB-3                                                                      
    218.5  16  NaNO.sub.3                                                 
                     9.5  1.07  3880   6980   6070                        
               Na.sub.2 S.sub.2 O.sub.3                                   
                     9.6                                                  
               NaSCN 0.5                                                  
LB-4                                                                      
    218.7  14  NaNO.sub.  3                                               
                     8.4  1.07  4300   7100   6930                        
               Na.sub.2 S.sub.2 O.sub.3                                   
                     9.6                                                  
               NaSCN 1.5                                                  
LB-5                                                                      
    218.5  16  NaNO.sub.3                                                 
                     6.3  1.07  4180   7250   7260                        
               Na.sub.2 S.sub.2 O.sub.3                                   
                     9.6                                                  
               NaSCN 3.5                                                  
LB-6                                                                      
    219.0  14  NaNO.sub.3                                                 
                     20.0 1.07  3200   5450   4950                        
LB-7                                                                      
    221.8  16  NaNO.sub.3                                                 
                     17.4 1.08  3700   6690   6000                        
               NaSCN 2.5                                                  
LB-8                                                                      
    217.2  15  NaNO.sub.3                                                 
                     16.1 1.07  4150   6990   6640                        
               NaSCN 2.5                                                  
               Na.sub.2 SO.sub.3                                          
                     0.5                                                  
               Na.sub.2 SO.sub.4                                          
                     0.6                                                  
LB-9                                                                      
    215.3  16  NaNO.sub.3                                                 
                     14.8 1.06  4280   6950   6740                        
               NaSCN 2.5                                                  
               Na.sub.2 SO.sub.3                                          
                     1.0                                                  
               Na.sub.2 SO.sub.4                                          
                     1.1                                                  
LB-10                                                                     
    216.0  16  NaNO.sub.3                                                 
                     9.6  1.06  4650   7510   6640                        
               NaSCN 2.5                                                  
               Na.sub.2 SO.sub.3                                          
                     3.0                                                  
               Na.sub.2 SO.sub.4                                          
                     3.4                                                  
LC-1                                                                      
    226.1  17  NaCl  20.0 1.11  3300   --     7990                        
LC-2                                                                      
    221.6  14  NaCl  2.0  1.07  3950   --     8200                        
               Na.sub.2 SO.sub.4                                          
                     1.0                                                  
               Na.sub.2 SO.sub.3                                          
                     1.0                                                  
               NaC.sub.7 H.sub.5 O.sub.3                                  
                     1.0                                                  
               NaNO.sub.3                                                 
                     4.3                                                  
__________________________________________________________________________