Effects of particle size distribution, surface area and chemical composition on Portland cement strength
The fineness of a Portland cement and its chemical composition are the key factors in determining cement strength characteristics. This paper describes a study of the relationship between cement particle size distribution and surface area, and the effects of size distribution, surface area and chemical composition on concrete strength. A new correlation between particle size distribution and surface area has been established and models which include the size distribution and chemical composition as factors have been developed to predict cement strength based on a large data base generated from industrial surveys. These models are useful in optimizing clinker grinding by simulation. The relationship between the cement compressive strength determined by the concrete mix and mortar test methods is also discussed.
The properties of the system EHEC/SDS/water in solution show considerable time dependence during several hours after preparation. The paper discusses various reasons for this time dependence. Similar time dependence in polymer solutions has been observed elsewhere. It is found that although the system properties vary, a true equilibrium is finally attained for all compositions. The most pronounced time dependence is shown in a region close to and above the CMC of a pure surfactant solution and for polymer concentrations at least equal to the critical overlap concentration. It is proposed that part of the explanation resides in the fact that in the solution preparation there appears intermediate states corresponding to high local polymer concentrations. Some quantitative aspects of the time dependence are also discussed.