Excellent athletic performance in baseball and softball batting is achieved through the momentary cognitive-motor processes. However, in previous studies, cognitive and motor processes are investigated separately. In this study, we focused on the difference in the time of swing onset (a delta onset) during a batting task where 17 elite female softball batters hit balls randomly thrown at two different speeds by pitchers. The delta onset included both cognitive and motor processes because the batters needed to anticipate the ball speed and discriminate their swing motion according to the time-to-contact. Then, we investigated the relationship between the delta onset and the batting outcomes of the batting task, and the relationship between the experimental outcomes and actual batting performance (batting average) over a season. We used path analysis to clarify the structure of the cognitive-motor processes and consequent performance. We found that the batters who had a larger delta onset attained superior batting outcomes  in the batting task, and these experimental outcomes explained 67% of the batting average in real games. On the other hand, the cognitive scores (judgement accuracy and rapidity) obtained from a button pressing task, where batters responded to a ball by pressing a button instead of actually swinging, explained only 34% of the batting average. Therefore, our model quantitatively describes the key cognitive-motor structure for athletes and can partially predict a batter's performance in real games. These findings suggest that it is important to employ both cognitive and motor processes in performing tasks, such as this batting task, to properly evaluate a batter's actual ability. Human action is strongly related to cognitive processes such as sensory processing, prediction, and decision making. These processes closely affect and restrain motor behavior associated with motor planning and execution  and the batting outcomes within a real batting experiment, where softball batters attempted to hit balls thrown at two speeds  by real pitchers. We also investigated the relationship between these experimental batting outcomes and actual batting performance obtained from real games (batting average). To clarify the structure of cognitive-motor processes and consequent performance, we performed path analysis using structural equation modeling (SEM). Based on the model, it was expected that the delta onset would influence experimental batting outcomes, and that these experimental outcomes would explain individual batting average in real games.As was mentioned earlier, psychology and neuroscience studies have conventionally used basic tasks such as a button pressing task to evaluate cognitive function. However, it is unclear to what extent the scores of these basic tasks explain the actual performance in real games. There is skepticism regarding the extent to which the results from unrealistic measurements can be applied to actual complex situations such as in sports  nor did that of a slowball . Furthermore, the batters' responses to pitchers A and B did not differ in the delta onset , in the exit velocity , and in the miss ratio  . Thus, our study was based on the premise that the difficulty to hit the pitches did not differ depending on the pitcher.Two female softball pitchers (pitchers A and B) from the same team as the batters volunteered to act as pitchers in the experiments. Both were right-handed pitchers. Each batter faced one of the two pitchers. Nine batters faced pitcher A and eight batters faced pitcher B. The pitch velocity of a fastball immediately before bat-ball contact did not differ between the pitchers  with a sampling frequency of 240 Hz. Ball movement around the time of bat-ball contact  was recorded using two high-speed cameras with a sampling frequency of 240 Hz . These cameras were placed diagonally at 45° in front of the batter, 10 m away from the home plate and protected with screens. The pitcher's camera was also used to detect the pitcher's ball release. The system was synchronized by a start signal from the motion capture system, which lit LEDs installed in front of the three cameras.In this study, the TTC was normalized to eliminate inter- and intra-personal variations. TTC was defined as the elapsed time between the ball being released by the pitcher and its crossing the mean impact position for each batter. Because each batter stood differently in the batter's box, we used the mean impact position for each batter. The TTCs across all analyzed trials were 444.9 ± 17.7 ms for fastballs and 621.6 ± 26.6 ms for slowballs. The TTC for a fastball and slowball was normalized as 100 and 140%, respectively, because the pitch velocities and TTCs of fastballs of both pitchers were ~1.4 times faster than those of slowballs .We analyzed the batter's swing onset time based on the temporal patterns of hand velocity. Hand velocity was defined as the velocity of the hand segment on the catcher's side  relative to the velocity of the pelvis segment in the pitcher-catcher direction. This was done to remove the translation component of the trunk from the swing onset. Swing onset was defined as the moment at which the hand velocity exceeded a certain threshold, which was 10% of the mean peak velocity for each batter (0.61 ± 0.09 m/s) . The swing velocity at stationary ball was measured using an easy-to-use instrument designed for swing analysis . Batters hit three stationary balls on a tee stand. The bat velocities immediately before bat-ball impact were averaged for each batter (km/h).The batting average is the most general index for evaluating a batter's ability in a real game performance, and values were taken from the same season as when the experiments were conducted (2017 season). This variable was calculated as the number of hits divided by the times at bat obtained from the results of official and practice matches against teams in the same league .In the button pressing task, the batters faced the same pitcher as in the batting task in a separate session. The order of the two tasks was counterbalanced across batters. The batters stood in the batter's box and were asked to press a button held by the dominant hand as accurately and rapidly as possible whenever the pitcher threw a fastball, but not when the pitcher threw a slowball. Batters were asked to place equal weight on both accuracy and rapidity. Each batter viewed 10 fastballs and 10 slowballs thrown by the pitchers at random. The pitcher's camera  was placed 8 m from the pitching rubber to the right of the pitcher to record the pitching motion at a sampling frequency of 240 Hz and detect the time when the pitcher released the ball. When the batter pressed the button, an LED installed in front of the pitcher's camera lit up. The time between the pitcher's ball release and LED lighting up were identified from video images.We employed the signal detection theory to evaluate the batters' judgment accuracy in the button pressing task  of the button pressing task and the batting average. We evaluated our models using the maximum likelihood method. In SEM, a model is considered a good fit if the value of the chi-square test is insignificant. In addition, fit indices are often used for model evaluation. We evaluated our models using the chi-square test and three indices: the comparative fit index (CFI), the Tucker-Lewis index (TLI), and the root mean square error of approximation (RMSEA). CFI and TLI values exceeding 0.95 and an RMSEA value of 0.05 or less were considered to represent good fit. We also calculated the R-square values for all the endogenous variables, namely, the exit velocity, miss ratio, and batting average presented in Figure 5. That is, two types of values were calculated for the batting average: the experimental batting outcomes obtained from the batting task .We used path analysis to clarify the structure of cognitive-motor processes in softball batting (lavaan R Ver. 3.4.2) Rosseel, . Path aning task  and the 2 test, p = 0.46; CFI = 1.00; TLI = 1.04; RMSEA = 0.00). All the path coefficients were significant (p < 0.01). The relationships between variables in the path analysis are shown as scatter plots in We investigated the structure of cognitive- motor processes using path analysis based on four explanatory variables: delta onset, exit velocity, miss ratio and batting average . The meaR2 = 0.33) and miss ratio (R2 = 0.42)  , suggestR2 = 0.67)  , suggestR2 = 0.33 and 0.42, respectively) which could be due to interpersonal variability. We divided the batters into two groups based on delta onset  (magenta and green circles shown in The contributions of the delta onset to the two batting outcomes (exit velocity and miss ratio) were significant but not large (p < 0.05), but not significant in group S . Batters with a larger delta onset (group L) and those with a larger swing velocity at stationary ball had a larger exit velocity  but not in group L   . This me = 0.18) . On the In the button pressing task, participants were asked to press a button as accurately and rapidly as possible whenever the pitcher threw a fastball. The mean ± SD values of HR, FAR, c and RT were 0.90 ± 0.16, 0.38 ± 0.20, −0.71 ± 0.51, and 263 ± 58 ms, respectively. Compared to HR, FAR was more inaccurate overall, though HR was more accurate at higher values while FAR was more accurate at lower values. Moreover, c for 15 of 17 batters had negative values, i.e., their responses were biased toward the fastballs. These results indicate that the batters tended to anticipate a fastball. Thus, FAR was regarded as an index of judgment accuracy, while RT was regarded as an index of judgment rapidity. Furthermore, RT refers to judgment time, and not the onset time of swing motion, because the mean RT was earlier than the mean actual time of swing onset in the batting task .r = −0.19, p = 0.46). None of the batters in our study seemed to use the potential strategy of delaying judgment to improve accuracy.Judgment accuracy and quickness are often considered to be in a trade-off relationship. In the current study, however, FAR and RT were not significantly correlated (Pearson's R2 = 0.34), but these could only explain 34% of the batting average, which was half of what the outcomes in the batting task could explain (67%).We investigated whether the judgement accuracy and rapidity explain the batting average . We founWe investigated the structure of cognitive-motor processes in softball batting. We found that the batters who had a larger delta onset performed very well in the batting task . We also found that experimental outcomes in the batting task explained 67% of the batting average in real games, while the cognitive scores in the button pressing task explained only 34% of it. In addition, our batters could be divided into two groups based on delta onset and batters had various batting strategies.t-test, p < 0.01), but that the onset time for fastballs was not different between groups . This means that batters who had a large delta onset delayed their swing onset for slowballs. In previous studies, batters were considered to expect a fastball when facing various ball speeds . This does not alter the authors' adherence to policies of Frontiers.


The article describes the selected methods of calculating the deflection of steel fiber reinforced concrete beams. Additionally, the results of the study on the deflection of steel fiber reinforced concrete beams based on waste sand are presented. This paper compares deflections measured during the four point bending test of the steel fiber reinforced, waste sand fine aggregate concrete beam with values determined in accordance with Eurocode 2, the proposal of Tan, Paramasivam, and Tan, the modified method of Alsayed, Bywalski, and Kaminski, and Amin, Foster, and Kaufmann’s method. The analysis conducted shows that the best accordance with the study and calculation results was obtained by using the modified Alsayed method. The main relationship defined in bend tested steel fiber reinforced concrete beams is the relation between the load and deflection . Based oThe methods used for the calculation of steel fiber reinforced concrete element deflections initially comprised small beams without bar reinforcement ,8. AmongTo make the comparison of methods easier, all symbols were unified.As1Area of tensile longitudinal steel reinforcement;As2Area of compressive longitudinal steel reinforcement;bWidth of member;fdDiameter of fiber;dDistance from the center of gravity of the stretched reinforcement to the most compressed beam edge;d′Distance from the center of gravity of the compressed reinforcement to the most compressed beam edge;cEModulus of elasticity of plain concrete;cfEModulus of elasticity of steel fiber reinforced concrete;sEModulus of elasticity of steel reinforcement;FApplied load;ctfTensile strength of concrete matrix;f0.5Residual tensile strength calculated at a Crack Mouth Opening Displacement, CMOD = 0.5 mm;hHeight of member;crITransformed moment of inertia for the cracked cross-section;gIGross moment of inertia;tkOrientation factor;flFiber length;aMApplied moment;crMCracking moment;nsE) and steel fiber reinforced concrete (cfE);Proportion of longitudinal steel reinforcement modulus of elasticity (fnfE) and steel fiber reinforced concrete (cfE);Proportion of steel fiber reinforcement modulus of elasticity , based rf, concrete small beams’ flexural strength (N/mm2); it can be calculated as a product of constant 0.622 and the square root of the compression strength defined for cylinders (N/mm2).To take into account the change of rigidity along the element length and the effect of tension stiffening, gross, transformed, and effective moments of inertia were used:crI, transformed moment of inertia for the cracked cross-section taken from the following equation:fA and f′A, steel fibers in the compressed and stretched zone surface areas; the method of calculation was proposed in 1978 by Hannant, making them dependent on fiber effective length (η1) and their orientation before cracking (η0) and after (η0′):η1, η0, and η0′, applied in Equation (5) can be determined using the proposal presented in 1987 by Lim, Paramasivam, and Lee [η1) depends on the length of fibers used (fl) in relation to the critical value (cl); for fl < cl, η1 = 0.5, otherwise, it should be calculated using the following equation:The values of  and Lee . The effcl, critical fiber length; it can be taken from a formula developed in 1974 by Swamy and Mangata in 1974 [fuσ, fiber ultimate tensile strength;τ, average interfacial bond stress between the fiber and matrix.η0) and after cracking (η0′) depend on the fiber length (fl) and element cross-section dimensions (b × h). Those values can be taken from the following equations:The fiber orientation factors before (cfE) can be taken from the following equation:cE) is calculated as a product of 4.73 and the square root of the compression strength defined for cylinders.Based on Equations (4) to (9), the effective moment of Equation (3) is determined for fixing the effective rigidity under the assumption that the steel fiber reinforced concrete modulus of elasticity , taking into account the influence of steel fibers through multiplication of the gross moment of inertia (gI) by the K coefficient. According to the method of the author, the influence of steel fibers on the deflection reduction is perceptible only after element cracking, so the influence of fibers on the modulus of elasticity and on the effective moment of inertia was not taken into account here. Therefore, Alsayed’s considerations pertained to a situation when the bending moment is higher than the cracking moment (M > crM). Therefore, the steel fiber reinforced concrete beam rigidity formula takes the following equation:In 1993, Alsayed put forward a proposal for the calculation of steel bar and fiber reinforced concrete beam deflection . It was K, coefficient taking into account the percentage of fibers and their slenderness ratio defined by the following equation:pfV, percentage of steel fibers,α1, α2, α3, coefficients defined by Alsayed based on his own research work, verified by the results of, among others, Swamy and Al-Ta’an [α1 = 0.45; α2 = 2.0, α3 = 1.25.Al-Ta’an ; α1 = 0.cE). Such a course of reasoning was dictated by the fact that Alsayed considered the influence of added fibers only on the moment of inertia value, whereas it is a well-known fact that the fibers usually cause a change of the modulus of elasticity. Furthermore, Alsayed limited his considerations only to the cracked element analysis, and this does not cover the entire problem. Therefore, the first stage of deflection (for non-cracked elements) should be determined, consequently with the relation to the second stage calculations (for cracked elements), in accordance with the formulae given in the ACI Building Code 318 [The methods of calculation of the deflection limit state in beams with added steel fibers presented in the Introduction and described hereabove pertain to steel fiber reinforced concrete elements made of plain concrete. Considering the specific properties of the steel fiber fine aggregate concrete mixtures made with waste sand, the above presented Alsayed method was modified. The proposed change refers to Equation (11), where the steel fiber fine aggregate concrete modulus of elasticity should be used instead of the modulus of elasticity for plain concrete  and tension stiffening effect  accounts for the influence of the steel fibers in the cracked portion of the cross-section. x in Amin, Foster, and Kaufmann’s method can be determined by considering the force equilibrium of the cracked section and strain compatibility , steel fibers applied (50/0.8 mm and 30/0.55 mm), the beam element longitudinal reinforcement ratio , and application of compressed reinforcement. Each beam had vertical stirrups spaced every 130 mm. Each series comprised 2 beams, 6 cylinders, and 12 cubic samples . Test elThe longitudinal beam reinforcement was made of ribbed steel (34GS grade) diameter 8, 10, 12, and 14 mm, whereas the transversal reinforcement was made of smooth steel (St3SX-b grade) diameter 4.5 mm. Only ribbed steel was tested for its mechanical properties. The tests performed were aimed at the definition of the yield point, tensile strength, and modulus of elasticity of the reinforcement bars .The rig for short term testing of beam elements was composed of a steel frame, hydraulic cylinder (fitted with the possibility to slide towards the top frame belt), and load control system. The static diagram of the tested elements was a single span freely supported beam loaded with two concentrated forces applied at 1/3 span between the support axes . The forMid-span , Item 5 Under load applying rollers . The number of stages was selected on the basis of calculated beam load bearing capacity and conditioned upon their longitudinal reinforcement ratio. Displacement values were measured in each of the analyzed loading stages. Deflection was calculated in reference to supports’ vertical movement. Examples of B-1 beam graphs are given in Lρ). The already mentioned Tan et al. method [Lρ). However, no significant impact of the applied steel fibers on the rigidity value was ascertained.The influence of steel fibers and the ratio of reinforcement on beam rigidity was determined experimentally based on the product of the bending moment and the distance between the deformation measurement locations divided by the sum of deformation increments (compressing for concrete and stretching for steel reinforcement). . method  and the . method , as wellII and gI, respectively. Differences between the theoretical rigidity of cracked cross-section values decreased with the increase of the stretched reinforcement ratio. Discrepancies between the theoretical and experimentally acquired c·IE products occurred also in particular load stages. They were considerable at the first stage (before cracking), whereas in the second stage (after cracking), they decayed with the increase of the load and stretched reinforcement ratio. They could also be caused by incorrect assessment of the theoretical cracking moments and omission of the additional curvature caused by steel fiber fine aggregate concrete shrinkage. Numerous works on the deflection of beams made of plain concrete confirmed that the method of calculation in [When comparing the graphs containing values calculated in accordance with the Eurocode 2  proposalation in  providedation in .The lowest deflection (10.12 mm) of the tested beams with the same ratio of reinforcement  was obtained for the plain concrete, for which the highest rigidity was obtained . SimilarThe sand used in the study, being the waste from an all-in aggregate hydroclassification process, was a perfect component in concrete with the addition of steel fibers. This was caused by a high fineness modulus, low changeability factor, and low mineral dust content, as well as the absence of impurities .A modification of the sand and concrete mixture with steel fibers and superplasticizer improved the matrix tensile and compressive strength. In the case of preliminarily designed sand concrete of the C12/15 class, the compressive strength of steel fiber fine aggregate concrete equivalent to Classes C25/30 and C30/37 was obtained respectively for fine aggregate concrete with glued fiber bundles 30/0.55 mm and loose fibers 50/0.8.The modified Alsayed method used for deflection calculation proposed in this paper described the relationship between the load and deflection well. When the calculations were compared with the experimental results, an average error of 3.7%, with a standard deviation of 9.2%, was obtained. The EC 2 method of the calculation of plain concrete elements’ deflection indicated, in relation to the analyzed steel fiber fine aggregate concrete beams, a small average error (0.7%) with a higher standard deviation (12.3%). However, it should be remembered that both methods gave values that were slightly underestimated in relation to the experimental values. Therefore, steel fiber fine aggregate concrete element deflection could be safely calculated with the application of the guidelines for plain concrete. Amin, Foster, and Kaufmann’s method gave results lower than the measured ones. The average error was 32.2%. The Bywalski and Kaminski method was the most complicated to use for deflection calculation, but the results were close to the measured values, with an average error of 8%, excluding the D and K series.The plain  concrete used in this study, with the declared compressive strength Class C35/45, featured higher strength properties compared with the two steel fiber fine aggregate concretes used of lower classes (C25/30 and C30/37). Nevertheless, the deflections of beams  made of steel fiber fine aggregate concrete and plain concrete were comparable. Therefore, the beam elements made of steel fiber sand concrete and plain concrete complied with the requirements put on any plain concrete elements in terms of deflection.Based on the studies performed and on the analysis of the results obtained, the following conclusions were formulated:


There is limited research reported on the effect of cyclic loading on cement-based repair materials as conducting such tests is time consuming. To overcome this issue, this study utilized a novel loading regime consisting of cycle groups with increasing stress amplitude to accelerate the test process. The Palmgren-Minder rule was used to estimate the fatigue life of repaired specimens. Specimens repaired with Mix M (cementitious repair mortar), which was estimated to have the highest 2-million-cycle fatigue endurance limit (77.4%), showed the longest fatigue life  during the cyclic loading test, the highest slant, and splitting bond strength among all repair mixes. The estimated two-million cycle fatigue endurance limit of Mix S (70.8%) was very similar to that was reported in literature (71%) using the traditional loading method. This study confirms the usefulness of Palmgren-Minder rule on estimating the fatigue life of repaired specimens. Additionally, the use of the novel loading regime showed the benefit of shortening the test process while producing results similar to those from using traditional loading methods. To improve the prediction accuracy, future research is required to modify the failure criteria to accommodate specimens that may not fail even when the average flexural strength is met. Concrete is widely used as a traditional building material in construction engineering, road engineering, and bridge engineering due to its low cost and excellent mechanical and durability performance . HoweverS-N (Stress-Number) diagrams, where S represents the load during cyclic loading and N means the number of cycles required to cause failure. Unlike most metals, concrete does not have a fatigue limit which means it will eventually fail after certain loading cycles. An example is that plain concrete subjected to repeated uniaxial tensile stresses appeared to fail before N reaches 2 × 106 cycles regardless of the stress level [S-N diagrams and estimate the fatigue life of materials under fatigue loading. In 1945, Miner [In the recent decade, the fatigue behavior of construction materials received great attention because natural or human activity-induced loads on buildings are often cyclic in essence . When coss level . To quanss level ,16,17, nss level ,19, or css level ,21,22. Tss level . Additioss level . The numss level . The conss level . Damage ss level . The adv5, Miner  introduc5, Miner , stress 5, Miner , thermod5, Miner , and fat5, Miner . The mod5, Miner .In the case of repaired structures, it is important to ensure sufficient fatigue life for the bond between the parent concrete and repair materials. Shah et al.  studied S-N curve. The estimated fatigue life in this study is compared with the results in previous literature to determine its liability. Additionally, the failure mode, hysteretic behavior, and dynamic elastic modulus drop of repaired samples after cyclic loading are analyzed and discussed, which is used to validate the predicted S-N curves. The findings of this study not only provide information on how to conduct a rapid and easy estimation of the fatigue life of repaired structures but explore the fatigue resilience performance of various repair materials.In summary, most of the aforementioned literature focused on the bond strength of cement-based repair concrete under fatigue loading, but scarce work studied other types of repair such as polymer-modified cementitious mortar, which outperform cement-based concrete repair in many aspects ,38,39,40A total of 4 mixes were prepared including one control mix developed in the lab and three commercial repair products locally available in the market. The control mix for the substrate, named Mix S, received the repair and had a design compressive strength of 50 MPa. The rationale for using 50 MPa concrete as the substrate was to minimize its own degradation  due to external loadings such that the fatigue resilience performance of different repair materials could be determined. Additionally, the use of Mix S as the substrate is the same as a previous study by authors  and its ASTM C39 . All thiASTM C39 ,48,49 anIn field applications, a common practice to rehabilitate structures is to remove delaminated concrete, clean the parent substrate and rebars, and apply the repair materials. In order to simulate in situ-damaged structures, prismatic beams with an induced cut on the tension side were prepared. Notched beams were prepared using Mix S and received the repair materials . All specimens were cast with a dimension of 75 mm × 100 mm × 400 mm, as shown in Prior to the application of the repair, surface roughening is an important step to ensure a good bond. Typically, quantifying the roughness of a concrete surface is mainly through comparing the target surface with nine standard concrete surface profile chips. These chips were proposed by International Concrete Repair Institute (ICRI) . In thisThe block was introduced into the mold before concrete placement. Cylindrical specimens were prepared for splitting tensile and slant shear bond tests. The dimension of the prepared specimens is illustrated in STM C882 . The 100P is the maximum applied load indicated by the test machine, L is the span length, b is the average width of specimen, and d is the average depth of specimen.A third-point loading test was conducted to determine the static flexural strength of the repaired prisms as per ASTM C78 . An MTS S-N curve for repaired specimens. In this study, the load variation was sinusoidal with a frequency of 10 Hz. Different loading force groups were used on intact and repaired beams as they had different flexural strength. Following the flexural strength test, a series of specimens were exposed to flexural cyclic loading, and the test setup was the same as shown in S-N curve was adopted from the work of Nieto et al. [S-N curve was based on the assumption that the curve can be approximated by a straight line in a logarithmic scale, as shown in Equation (2). By means of Palmgren-Miner rule and Goodman linear model [b in Equation (2). As demonstrated in Equation (3), the accumulative damage factor N is the number of cycles to failure, S is the stress applied on the specimen, and b is the slope of the straight line.ith cycle group, ith cycle group, and ith cycle group.In this study, the use of cycle groups to obtain an o et al. . Differeo et al. , this star model , EquatioThe Resonant frequency test was performed when each cycle group is completed to determine the changes in dynamic modulus of elasticity  and repair materials are determined using methods shown in The slant shear test was performed following ASTM C882 . The speThe life cycle of the repaired beams under cyclic load is affected by the bond strength of the repair materials . In thisThe failure mode can be classified into two types, adhesive failure and cohesive failure. Cohesion failure occurs when either the substrate concrete or repair material fails. When the substrate concrete fails, some substrate materials will be left on the half cylinder of repair materials. Adhesion failure occurs when fracture is at the exact concrete-repair interface leaving a clean and smooth failure interface. To simulate in situ-repaired structures, prismatic beams with a square patch on the tension side were prepared and tested under cyclic load. To accelerate the test process, modified loading regime consisting of cycle groups of increasing cyclic stress amplitude is used. The hysteretic force-displacement response of each specimen after each load cycle is recorded, which reflects the damage accumulation and energy absorption capability of the samples . Figure neficial . Note thDynamic elastic modulus  showed twice the flexural strength of repaired samples, better energy absorption capacity (higher permanent deformation), and the least drop in ar model , it is aterature ,76,77 reS-N curve and 2-million-cycle endurance limit of different repaired specimens were validated by comparing with results including the number of cycles to failure, Mix M (cementitious repair mortar) showed superior bond performance compared with different repair mixes currently used in the field. Mix M had an average shear bond strength of 12.3 MPa and 16.7 MPa and tensile bond strength of 1.4 MPa and 2.3 MPa at 14 and 28 days of curing, respectively. This study confirmed the benefit of using high-strength materials as repair to improve the bond strength.The feasibility of using the Palmgren-Miner rule and Goodman linear model  to estimThis study found the usefulness of using cycle groups of increasing cyclic stress amplitude to accelerate the fatigue test process. The two-million cycle fatigue endurance limit estimated using cycle groups of Mix S (70.8%) was very similar to what was reported in the literature (71%) using the traditional cyclic loading method. The use of this method will help shorten the time for performing fatigue tests.The substrate–repair interface was found to have an important role in determining the static and cyclic flexural performance of the repaired structure. Mix S (control mix) showed twice the flexural strength of repaired samples, better energy absorption capability (higher permanent deformation), and the least drop in S-N curve was in line with bond strength, failure pattern, and modulus of elasticity measurements. Specimens repaired with Mix F (cementitious repair concrete), which had a steeper slope compared to other mixes, had the highest drop in elastic modulus (5.2%) and lowest shear and tensile bond strength.The predicted The limitation of the Palmgren-Miner rule is that it assumes that the specimen will fail when the damage accumulation reaches 100%, which is contrary to the observations from past literature ,82,83. FThis study explored the applicability of the Palmgren-Miner rule on estimating the fatigue life of repaired concrete structures under cyclic loading. A novel loading regime consisting of increasing cyclic stress amplitude was used to accelerate the test process. The predicted


There is no consensus if electronic nicotine delivery systems (ENDS) should be used to reduce harm among the smoking population. Physicians, who represent a trusted source of health communication, are exposed to a range of often conflicting ENDS information and this information may be relayed to patients looking to quit smoking. Previous studies have examined ENDS content of various sources of media but there is a lack of knowledge about ENDS content in medical journals. We analyzed 421 ENDS publications printed between 2012 and 2018 from PubMed’s Core Clinical Journal list. Publications were analyzed based on publication type, journal type, study design, geographic focus, theme, terminology, outcomes, and positive/negative statements. The number of ENDS publications grew since 2012, and peaked in 2015. Across all years, negative statements about ENDS outnumbered positive statements, though this difference decreased over time. Over time, negative statements about “toxins and carcinogens” were made less frequently, while negative statements about “gateway effects” and “youth appeal” became more prevalent. UK journals had fewer negative statements relative to US journals. Only 12.6% of publications included guidance for healthcare professionals about ENDS. As published ENDS topics change over time, physicians’ communications with patients may be impacted. Electronic nicotine delivery systems (ENDS) are battery-powered devices that deliver nicotine and flavors to a user through an inhaled aerosol generated by vaporizing a heated liquid. ENDS have been available in the United States since 2006 , and becThere is no consensus among healthcare providers regarding recommending ENDS to patients who smoke as a means to reduce harm. Since ENDS contain lower levels of toxicants compared to combustible tobacco , some bePhysicians are an important and trusted source of health information for patients ,13. SeveJournals are one of many sources of information physicians use to inform practice decisions and it is important to understand the e-cigarette content and messages of these sources, particularly with regard to the safety and effectiveness of ENDS. Several studies have analyzed the content of ENDS material in the news , magazinThis study utilized searches in PubMed, an online citation database developed by the National Center for Biotechnology Information which includes access to over 26 million scientific articles . ElectroThe Core Clinical list was searched for all documents published between 2012 and the end of 2018. Publications were included if they contained at least one of the following keywords under ‘All Fields’: “electronic cigarette(s)”, “electronic nicotine delivery system(s)”, “e-cig(s)”, “e-cigarette(s)”, “vape”, “vaping”, and “JUUL”. JUUL was the only brand name searched for due to its dominance of the e-cigarette market share . AuthorsPublication types were categorized as defined by Scopus  and inclResearch assistants evaluated all downloaded publications and excluded publications that contained no ENDS content, including publications that contained our search keywords but did not focus on or discuss ENDS, after confirmation from a second research assistant. A content coding system was developed based on previous content analyses of ENDS news stories . Where pEach publication was coded for the geographic level of focus of the research/discussion presented , publication type , terminology , ENDS themes , positive claims about ENDS made directly by authors , and negative claims about ENDS made directly by authors . If a single sentence presented multiple points of view, it would be coded as both a positive and negative statement. Sentences that were agnostic and discussed the possibility of a positive or negative were not coded as either . Sentences describing comparative risk would be coded as a positive and a negative ; this statement would be coded as a negative due to the claim of toxins and carcinogens, but a positive due to less relative risk compared to cigarettes. If a specific statement theme was made, it was counted just one time. For example, if the statement “e-cigarettes are less risky than cigarettes” was made five times throughout a publication, it would still just be coded one time. For the purpose of this project, national publications were defined as those focused on the United States, and not a specific state or region within the country. If the geographic focus was on the state-level, we coded the specific state. If the publication type was a research article, we coded the type of study design used . If specific ENDS related outcomes were stated, we recorded which measures were reported . We also recorded if the publication made any mention of the following: Food and Drug Administration regulation, marketing restrictions, and flavors. We identified each journal’s country of publication to identify potential differences in ENDS positivity/negativity and thematic contrasts by country. This analysis was based on the observation of various ENDS position papers and public statements from organizations in several countries over the years. This assessment considered the country where the journal is published rather than the county of origin of the authors. India was dropped from our journal origination analysis because it only included a single publication, limiting the power of these comparisons.To assess inter-rater reliability after the pilot phase, two research assistants both coded a random selection of 10% of publications, with a resulting Cohen’s Kappa statistic of 0.89, signifying very good agreement. All discrepancies were resolved during the pilot phase by re-reviewing publications and through group discussion. Descriptive statistics were used to present the frequency of publication themes and statements and Chi-square tests were conducted to compare the variable distribution by publication type as well as journal’s country of origin. To minimize likelihood of a Type 1 error from multiple tests, we used a conservative significance level of 0.01 for all analyses using R (Version 3.4.2) .n = 114), and decreased annually since 2015, with only 23 publications in 2018. Searching the core clinical journals on PubMed for our keywords resulted in 555 publications. After applying inclusion and exclusion criteria, a total of 421 publications were coded and analyzed. Of the 421 publications, 105 were research articles (24.9%), 100 were letters (to the editor) (23.8%), 63 were notes (15.0%), 55 were editorials (13.1%), 53 were short surveys (12.6%), and 45 were reviews (10.7%). Of the 105 research articles, 40 utilized a cross-sectional study design (38.1%), 18 were cohort studies (17.1%), 5 were randomized control trials (4.8%), 3 were case control studies (2.9%), and 39 used other design types (37.1%).n = 33, 7.9%), The Lancet , The New England Journal of Medicine , The American Journal of Public Health , The Canadian Medical Association Journal , Journal of the American Medical Association , Journal of the American Medical Association: Pediatrics , CHEST , and Annals of Internal Medicine .The top 10 core clinical journals with electronic cigarette publications were The British Medical Journal (BMJ) , Pediatrics , 158 had an international focus (37.6%), and 24 focused on particular US states (5.7%). Of the 24 publications that had a state-level focus, 8 were focused on California (33.3%), 3 on Connecticut (12.5%), 3 on New York (12.5%), 2 on Hawaii (8.3%), and 2 on Kentucky (8.3%). Alaska, Illinois, Michigan, Minnesota, Oklahoma, and ‘Midwest states’ were each the focus of a single study.The frequency of themes covered in ENDS studies was significantly associated with publication type. The most common theme in all publications was health or safety risks (64.1%), found mostly in reviews (80.6%). Policy or regulation issues were present in 53.0% of all publications, and most common in reviews (72.4%). Patterns of use and prevalence was the theme of 46.6% of all publications, and was most commonly found in articles (62.9%). The theme “use for cessation” was in 45.6% of all publications, and was found most in reviews (59.2%). Perceptions about ENDS  was found in 21.6% of all publications, and had the highest prevalence in articles (32.4%). The least common theme, guidance for healthcare professionals, was prevalent in just 12.6% of publications. In terms of ENDS outcomes measured or discussed, 15.2% of all publications provided data and results about ENDS cessation efficacy and 15.0% provided data and results on ENDS toxicant levels. Among publications that provided ENDS toxicant data, 10.0% compared these levels to toxicant levels in cigarettes. Publications also discussed flavors in ENDS (37.8%), United States Food and Drug Administration (FDA) regulation (33.3%), and marketing restrictions (32.5%).Regarding negative statements, 36.3% of all publications stated ENDS appealed to children or acted as a gateway to other forms of tobacco, 30.4% mentioned ENDS exposed users to toxins or carcinogens, and 30.2% stated nicotine is addictive or harmful. Another 27.3% of all publications mentioned ENDS prevented quitting or promoted dual use of tobacco products and 27.3% stated the health effects of ENDS are unknown. We found that 17.6% of all publications mentioned ENDS were not effective for smoking cessation.n = 42 journals), the United Kingdom , and Canada . There were 260 publications from journals published in the United States, 140 publications in journals published in the United Kingdom, and 20 publications in a single Canadian Journal. Over the time period of this analysis, statements from national organizations in different countries varied in terms of their general positive or negative sentiments regarding ENDS. Therefore, we chose to analyze themes based on country where the journal was published. The journals represented in our sample originated from the United States  of reviews provided guidance for healthcare professionals. This was surprising because the use of ENDS for smoking cessation, either positively or negatively, is a widely debated topic in public health. We found core clinical reviews to be more positive and negative compared to core clinical articles. One potential hypothesis is that reviews are referencing non-clinical articles which could support more positive and negative findings. When examined over time, the number of negative statements about ENDS were much higher than positive statements, however the decline in number of negative statements has outpaced those of positive ones since 2014. In particular, negative statements such as unknown health effects, toxins, and carcinogen exposure decreased over time. Concerns regarding the gateway effect and appeal to children increased from 2012, indicating a potential shift in focus. It should be noted that these analyses occurred prior to the recent attention to e-cigarette or vaping-device associated lung injury (EVALI) in 2019 . Future When we compared positive and negative statements made in journals based upon country of journal origin, we found that journals in the US had a higher percentage of negative statements regarding unknown health effects, nicotine harms, and exposure to toxins or carcinogens compared to those from the UK. The United Kingdom has been on the forefront of the harm reduction debate , and theOne limitation of this study is the restriction to core clinical publications which may miss journals physicians routinely access, however, this appears to be the best group of literature that physicians commonly request. Another potential limitation is our decision to present counts of positive and negative statements over time. This decision could skew results as longer manuscripts can contain more statements, but this is a more objective measure than deciding if an overall paper is positive, negative, or leaning in one direction. Another limitation is our decision to analyze by the country of the journal rather than the country of the authors; future studies would benefit from looking at specific author affiliations. Additionally, we did not distinguish whether positive or negative statements were made towards specific ENDS devices, but our analysis found that nearly all publications made general references to “e-cigarettes” or “ENDS devices.” As more evidence emerges regarding the health effects of ENDS, messages that clinicians relay to their patients might change over time. Physicians are an important and trusted source of information for their patients, and patients considering switching to e-cigarettes will expect their physicians to be knowledgeable about ENDS health effects and effectiveness for smoking cessation. Future studies should explore how the publication contents differ when the focus of a publication is on adults, adolescents, or pediatrics. Future studies should analyze the contents of ENDS publications beyond the core clinical journals so we have a larger picture of the content physicians and researchers are being exposed to. Future studies should also compare the content in journals to other sources of media and information that can influence a physician’s attitude towards ENDS.


Third-generation cephalosporins (3GC) remain the first-choice empiric antibiotic for severe infection in many sub-Saharan African hospitals. In Malawi, the limited availability of alternatives means that strategies to prevent the spread of 3GC resistance are imperative; however, suitable approaches to antimicrobial stewardship (AMS) in low-income settings are not well studied.We introduced an AMS intervention to Queen Elizabeth Central Hospital in Blantyre. The intervention consisted of a prescribing application for smartphones and regular point-prevalence surveys with prescriber feedback. We evaluate the effects of the intervention on 3GC usage and on the cost of providing antibiotics. Using a thematic analysis of semi-structured interviews and participant observations, we additionally evaluate the acceptability of the stewardship program.The proportion of antibiotic prescriptions for a 3GC reduced from 193/241 (80.1%) to 177/330  with no change in the case-fatality rate. The cost analysis estimated an annual savings of US$15 000. Qualitative research revealed trust in the guideline and found that its accessibility through smartphones helpful to guide clinical decisions. Operational health-system barriers and hierarchal clinical relationships lead to continued reliance on 3GC.We report the successful introduction of an antimicrobial stewardship approach in Malawi. By focusing on pragmatic interventions and simple aims, we demonstrate the feasibility, acceptability, and cost savings of a stewardship program where resources are limited. In doing so, we provide a suitable starting point for expansions of AMS interventions in this and other low-income settings. An antimicrobial stewardship program, consisting of a prescribing guideline and point-prevalence surveys with prescriber feedback, was introduced at Queen Elizabeth Central Hospital in Malawi. The program was effective in reducing third-generation cephalosporin usage and was potentially cost-saving for the hospital. Infection with antimicrobial resistant (AMR) pathogens is associated with high morbidity and mortality for patients and a significant economic burden on health systems , 2. In sCeftriaxone, a parenteral third-generation cephalosporin (3GC), has long been the antibiotic of choice in many sSA hospitals, with its once-daily dosing regimen and broad spectrum of activity making it a useful and convenient choice in settings where diagnostics and nursing capacities are limited , 9. In sIn Malawi, sentinel surveillance from patients presenting to Queen Elizabeth Central Hospital (QECH) in Blantyre has demonstrated a rapid rise in 3GC resistance amongst bloodstream Enterobacterales, occurring contemporaneously with the widespread roll-out of ceftriaxone . A limitThe aim of this work was to establish and evaluate a formal AMS program on the adult medical wards at QECH. We conceived and introduced a locally appropriate antibiotic guideline and evaluated its impact on ceftriaxone usage and the cost of antibiotic provisions. Incorporating qualitative methodology, we additionally aimed to understand the barriers to and enablers of our stewardship approach.Malawi is a low-income country with a low health-care expenditure (~3% gross domestic product) . QECH isThe stewardship program had 3 phases: a preimplementation prescribing survey, designed to identify stewardship targets (January 2016); the implementation of an antibiotic guideline (June 2016); and 2 postimplementation prescribing surveys (January 2017 and January 2018). Point-prevalence surveys (PPS) with feedback to prescribers began at the start of the implementation phase and continued for 28 months. The study methods are described below, as well as in more detail in the Supplementary Material.Inpatient records were reviewed to collect data on key stewardship quality indicators. The preimplementation survey was carried out by R. L., D. K., and A. K. Then, R. L. drafted the antibiotic guideline. Postimplementation surveys were carried out by a doctor who was not involved in the implementation phase (K. H.). We adapted standardized stewardship quality indicators to suit local practice , focusinA series of multidisciplinary team meetings were held to establish the AMS program, convening clinicians, nursing managers, hospital directorship, pharmacists, and microbiologists. All key decisions involved senior clinicians active at QECH. Local antimicrobial susceptibility trends, antibiotic availability, and national guidelines were reviewed and used to design a consensus-based antibiotic guideline that was reviewed by all senior clinicians in the departments. In Malawi, the burden of severe bacterial infection is high, and it is critical that AMS does not restrict access to potentially lifesaving therapy . Our guiwww.microguide.eu/). Microguide allows prescribers to access hospital-specific guidelines on their mobile devices or the hospital intranet. The QECH version can be viewed at https://viewer.microguide.global/QECH/ADULT4.The guideline was distributed using booklets and posters and as a smartphone antibiotic application, Microguide . Interviewees were purposively sampled based on their role in prescribing antibiotics, and observations were conducted on medical ward rounds and in morning meetings. Transcripts and field notes were imported into the Nvivo software package  and a thematic analysis was conducted.We explored the impact of the stewardship intervention on the direct health-provider costs of supplying antibiotics at QECH. First, we used data captured in the 3 prescribing surveys to estimate the total cost of all antibiotics given to participants in each survey. We divided this total cost by the total number of participants in each of the 3 surveys to estimate the average cost per participant. Secondly, we modelled how the stewardship intervention would impact the mean cost per patient and the total annual cost of providing antibiotics to those admitted to the 3 medical wards . We also estimated the annual cost of implementing the intervention .2 test. Confidence intervals (CIs) were calculated using the Wilson method. Assuming that errors would be approximately normally distributed, a linear regression model was used to detect linear trends in the prevalences of ceftriaxone and all antibiotic prescriptions over time. Seasonality was adjusted for using harmonic terms with a 1-year period. For the PPS, data were recorded as missing if a patient file was not available at the time the survey was carried out. We assumed that missing records were missing at random and, therefore, were not likely to bias the prevalence estimates. Data were analyzed using the R statistical package, Version 3.6.0 .Stewardship indicators from antibiotic surveys were described as proportions, and comparisons between pre -and postimplementation groups were done using the χ The study was approved by the Research Ethics Committees of the University of Malawi, the College of Medicine (P.10/15/1811), and the Liverpool School of Tropical Medicine (15–052RS).The records of 203 patients were reviewed in the preimplementation survey (Survey 1). There were 100 records reviewed in the first postimplementation survey (Survey 2) and 200 in the second (Survey 3).Salmonella Typhi, Salmonella Typhimurium, and Klebsiella pneumoniae  to 177/330  between the first and last surveys, and the median length of ceftriaxone course was reduced from 5 to 4 days . This paP < .01). Although P = .15; P = .19 and P = .65 for the sine and cosine terms, respectively) or overall antibiotic usage .The median number of charts included in each PPS was 100 . A median of 2 files  were recorded as missing in each survey. In the first PPS, 78% of patients on the ward were receiving ceftriaxone and 86% were receiving at least 1 antibiotic of any class. The total costs of antibiotics prescribed to patients in Survey 1, Survey 2, and Survey 3 were US$1907.04, US$584.78, and US$1404.34, respectively. The average costs per patient were US$9.39 (Survey 1), US$5.85 (Survey 2), and US$7.02  and the regular consultation of Microguide was observed during ward rounds. This was in marked contrast to the preimplementation interviews, in which participants cited a range of resources used to guide prescribing and difficulty in finding locally relevant information (quotes 1.3–1.4). Junior-level doctors, in particular, perceived that they now had a new resource that would guide them towards narrow-spectrum antibiotics, and valued the ability to access the guideline on their smartphones (quote 1.5).Most participants felt invested in the guideline, noting the department’s involvement in its inception and development (quotes 2.1–2.2). The locally appropriate nature of the guidance was cited as crucial in almost all postimplementation interviews, in particular with regard to antibiotic availability and pathogens (quotes 2.2–2.4).The process surrounding the introduction of the stewardship intervention was perceived to raise awareness of AMR and of overprescribing within the department. Physicians of all cadres reported thinking more about their antibiotic prescribing practices than before the intervention (quotes 3.1–3.2).Multiple routes to ceftriaxone overprescribing were identified in the thematic analysis in the pre- and postimplementation phase.An overarching theme across interviews and observations was the influence of resources on prescribing practices. Limited access to alternative antibiotics (quotes 4.1–4.3) and comprehensive diagnostics (quote 4.4), as well as an inadequate nursing capacity favoring antibiotics with once-daily dosing regimens (quote 4.5), were frequently cited as reasons for ceftriaxone use and overuse, as perceived by participants.Hierarchical relationships between the different cadres of clinical staff shaped prescribing practices. Junior team members invariably took direction from senior colleagues on prescribing, and a rigid hierarchy frequently prohibited junior team members from challenging the prescribing of peers or senior colleagues (quotes 5.1–5.3).Participants frequently described ceftriaxone as the rational choice in the clinical situations they faced, with the risk of undertreating individual patients taking priority over the population-level consequences of antibiotic overuse. Junior doctors considered intravenous antibiotics to be inherently superior to oral, particularly amongst inpatients, where the burdens of HIV and infection are high (quotes 6.1–6.3).We demonstrate that antimicrobial stewardship is feasible and effective in a low-income country and in a hospital that has no specialist clinical microbiology or ward-level pharmacy service, a limited antibiotic formulary, and no previous ethos of stewardship. A locally appropriate, pragmatic antibiotic guideline using smartphone technology, supported by a simple educational strategy of weekly “reminders,” led to a significant reduction in 3GC usage, an increase in the proportion of 48-hour antibiotic reviews, and a cost savings of over US$15 000 for the medical wards. Critically, the case fatality rates did not change between the pre- and postimplementation surveys, nor on the medical wards in general during the study period.Unlike in high-income settings, the evidence for successful stewardship in low- and middle-income countries is limited. AMS programs from Cambodia and South Africa have demonstrated substantial impacts. However, whilst resource-constrained, these settings are very different from Malawi, and their stewardship successes relied upon established pharmacy infrastructures , 21, speWhilst QECH benefits from sustained access to a quality-assured blood culture service, we highlight multiple operational barriers to implementing stewardship that are distinct to low- and middle-income countries , but espThis study has several limitations. Although the PPS show a significant decline in the prevalence of ceftriaxone usage over the study period, we have limited data from the preimplementation phase. However, previous studies at QECH prior to the intervention showed ceftriaxone prescribing prevalences of 70–84% , 30, conWe have demonstrated the sustainability of the AMS program over a 28-month period, but measuring its long-term impact, whilst essential, is outside the scope of this study. The potential cost savings achieved by the reduction in antibiotic usage is key to the sustainability of our program, and an antibiotic pharmacist could continue the regular PPS. Involving clinical departments and hospital management in guideline development is fundamental to its sustainability. Our guideline is integrated into departmental teaching and the Microguide application provides a function for real-time feedback from prescribers, allowing regular updates to be incorporated as often as required.AMS programs in low-income countries are challenged by the dual burden of a high prevalence of severe, often drug-resistant infections alongside insecure, variable access to a range of effective antimicrobials. We demonstrate that stewardship can be adapted to this setting and, by focusing on pragmatic interventions and simple targets, we show the feasibility, acceptability, and cost savings of a stewardship program in Malawi, which was successful in reducing third-generation cephalosporin usage. In doing so, we provide a suitable starting point for expanded, large-scale stewardship interventions in this and other resource-limited settings.ciaa162_suppl_Supplementary_Figures_1Click here for additional data file.ciaa162_suppl_Supplementary_MaterialsClick here for additional data file.


Maintenance of reinforced concrete structures is a prevailing topic, especially with regard to lifeline structures and bridges, many of which are now designed with a service life beyond 100 years. Reinforcement made of ordinary (carbon) steel may corrode in aggressive environments. Stainless steel, being much more resistant to corrosion, is a valid solution to facilitate the protection of the works, increasing the service life and reducing the need for repair and maintenance. Despite the potential for stainless steel to reduce maintenance costs, studies investigating the influence of stainless steel on the behavior of reinforced concrete structures are limited. This study investigated the bond behavior of stainless steel rebars by means of experimental tests on reinforced concrete specimens with different concrete cover thicknesses, concrete strengths, and bar diameters. In each case, identical specimens with carbon steel reinforcement were tested for comparison. The failure modes of the specimens were examined, and a bond stress–slip relationship for stainless steel bars was established. This research shows that the bond behavior of stainless steel rebars is comparable to that of carbon steel bars. Stainless steel is a viable alternative to carbon for use as reinforcement in reinforced concrete structures. Stainless steel has been proven to be effective in reducing the risk of corrosion, thereby increasing the service life of structures, as well as lowering maintenance and monitoring costs.Reinforcement made of ordinary steel may corrode when (a) carbonation reduces the alkalinity of the concrete, which can therefore no longer exert its own passivating action and/or (b) the chloride content of the concrete in contact with the reinforcement is higher than a critical threshold. In areas where either of these are likely to occur, the use of ordinary steel reinforcement should be avoided.Another factor that increases the risk of corrosion of reinforcing steel is extreme heat, as in the case of fire. The high temperature and corresponding internal vapor pressure cause the breakaway of concrete cover, known as spalling ,2.The use of stainless steel is particularly advisable for lifelines , such as bridges ,4, many Because stainless steel may cost 6–10 times more than ordinary steel, to contain the cost of the works, it is possible to use both types of steel reinforcements, with stainless steel concentrated in parts of the structure that are most prone to corrosion, such as joints in bridges.Although the use of stainless steel reinforcement has been recommended in aggressive environments ,6,7, stuIn , the tenIn , the resIn , the bonIn , an expeIn , the bonIn , stainleIn ,16, expeThe purpose of this research work was to investigate the bond behavior of concrete elements reinforced by means of stainless steel rebars and compare this behavior to that of elements reinforced by conventional carbon steel rebars.The investigation was carried out by means of experimental tests on specimens with different concrete cover thicknesses, concrete strengths, and bar diameters. The specimens were subjected to tensile stresses parallel to the reinforcement. fib Model Code 2010 . T. T27]. TIn this research work, the modified version of Danish standard pull-out test, represented in For each specimen, two transducers were used to measure the slip of each of the two bars with respect to the concrete during the tensile test. For this purpose, rigid iron supports were mounted on each bar so that the transducer, mounted on the concrete block, could push against the support and measure the relative steel bar–concrete slip. Only the measurements of the short bar were then used to define the bond stress–slip relationship. The bond slip was computed by measuring the total slip and subtracting the elongation of the bar between the transducer and the concrete surface.Tensile force was applied to the lower bar, while the upper one was kept firm, by a universal MTS 500kN  machine operated by displacement control. This type of control made it possible to record the softening branch of the force–displacement diagrams. Measurements were continued until the force value reached zero.dl1/ϕ, was less than 5 so that it was possible to consider a uniform bond stress distribution along this portion of the bar [The specimens consisted of concrete prisms with square or circular base shape , where t the bar .3 of concrete was as follows:Aggregates weight 1950 kgCement   340 kgWater   170 L (water/cement ratio = 0.5)The mix design used to produce 1 mThe aggregates were composed of a mix of washed sand (diameter of 0–5 mm) and gravel (diameter of 5–20 mm).The cement used was a hydraulic binder obtained from the grinding of Portland clinker, natural limestone, and gypsum, with a 28-day strength greater than 32.5 MPa.The goal of the mix design was to obtain concrete with a cubic characteristic strength equal to 30 MPa. Hence, some samples with different percentages of coarse aggregates, fine aggregates, water, and cement were made and tested in advance to find the best mix design proportions suitable to obtained this strength.cmR, was considered for each group of tested samples, and the mean cylinder concrete compressive and tensile strengths were calculated as cmf = 0.83·cmR and ctmf = 0.3·(cmf)2/3 [The specimens  were rea(fcm)2/3 , respecta is the square base side length, d is the circular base diameter, and c is the minimum bar concrete cover. The concrete compressive strength is reported in column (7). For each specimen, the force leading to concrete tensile failure, c,failureF, was calculated by multiplying the mean concrete tensile strength by the concrete net area τbu,d1l in c/ϕ < 5 and to The force leading to the specimen bond failure, h ld1 in :(3)FbmaexpF, is reported in The maximum force attained by each specimen during the experimental tests, -a/ϕ or d/ϕ ratios ;concrete tensile failure, which was evidenced by concrete rupture in the specimen section where the longitudinal bars were interrupted, as shown in -a/ϕ or d/ϕ ratios; andpull-out failure, which was evidenced by the shorter bar slipping out of the concrete, accompanied by the dragging of a concrete cone around the bar, as shown in -splitting failure, which was evidenced by the radial spreading of longitudinal cracks, which reached the exterior surface of the specimen, as shown in Three failure types were observed:In some specimens, the slipping of the shorter bar was accompanied by splitting longitudinal cracks. In these cases, the failure was classified as pull-out type if it produced a pull-out cone; otherwise, a splitting failure was assigned. The failure types assigned to all the specimens are reported in τ–s) curve was plotted for the shorter bar considering the bond stress constant along the embedded portion. In For each tested specimen, the bond stress–slip , which relates the bond stress An objective of this investigation was the identification of a relationship based on the mulation  for the rd tests  for carbThe experimental For each experimental curve associated with only a pull-out failure, The The The By considering both the curves associated with pull-out failure and the ones associated with concrete and/or splitting failure, a nonlinear regression analysis was performed to estimate the In this work, an attempt was made to adapt the above formula to the case where stainless steel is used in tensile concrete by statistically treating the test results for the specimens with stainless steel rebars. The same analysis was completed for the specimens with carbon steel rebars. To this end, the following steps were taken.Each analytical step was executed using the software R .The aforementioned analysis was performed separately for the specimens with stainless steel rebars and for the specimens with carbon steel rebars. k are reported in α are not because this parameter was obtained from a nonlinear regression analysis performed on all the acquired points of the experimental curves’ ascending branch. The obtained values of the bond stress relationship parameters for both groups of specimens are also reported in The measured values of parameters -blue for specimens S1, S19, S33, and S41;-light green for specimens S2, S20, S34, and S42;-light blue for specimens S7, S25, S39, and S47;-purple for specimens S8, S26, S40, and S48;-black for specimens S9, S27, S49, and S53;-red for specimens S10, S28, S50, and S54;-fuchsia for specimens S11, S29, S51, and S55;-green for specimens S12, S30, S52, and S56;-orange for specimens S13 and S31;-dark yellow for specimens S14 and S32.The proposed bond stress–slip relationship for each concrete strength is also plotted in the corresponding figures. For both the proposed bond stress relationships, the only varying parameter was The curve line for specimens that exhibited pull-out failure is dotted, while that for specimens that exhibited splitting failure is continuous.Specimens that exhibited concrete tensile failure are all represented by grey continuous lines.k resulted in an accurate prediction of the bond strength because the AVG of the ratio of measured to proposed values was practically equal to 1 for both specimen types; moreover, the predictions were precise with COV of 0.106 for specimens with stainless steel rebars and COV = 0.207 for specimens with carbon steel bars. The k value, equal to 2 for both specimen types, was 20% lower than the one proposed in the fib relationship (Equation (1)), which is valid for concrete under compressive stress.For both groups of specimens, the value proposed for parameter α, which represents the slope of the bond stress–slip curve because the COV value exceeded 0.3 for both types of specimens. Regarding this parameter, it should be noted that, on average, the specimens with thinner cover c exhibited bond stress–slip curves with higher stiffness (steep curve slope), while specimens with greater cover exhibited curves with a lower stiffness (lower slope). This can be appreciated by comparing specimens that were identical in all characteristics apart from the cover, such as those reported in α on the basis of the cover seems to be an unnecessary complication considering that not even the fib relationship accounts for it. For parameter α, the relationship described herein proposes the same value as that proposed in the fib relationship (α = 0.4) for specimens with stainless steel rebars (α = 0.4) and a lower value (α = 0.3) for specimens with carbon steel rebars.A wider range of values was observed for parameter α, the carbon steel specimens with thinner cover c exhibited bond stress–slip curves different from those of specimens with greater cover. In particular, the measured slip k remained approximately equal to 2, and the new value of α was around 0.4. Regarding parameter α being equal to the value proposed by the fib relationship (α = 0.4) for both types of specimens. However, the fib relationship (Equation (5)). The finding on fib relationship.On the basis of the previous evaluation, excluding the outliers for specimens with carbon steel rebars, the result was On the whole, it can be said that the bond behavior of the stainless steel rebars was quite similar to that of the carbon steel ones. The differences, mainly regarding the peak slip value With reference to the values in By considering the above observations, the parameters of the bond stress–slip relationships that may be used for stainless steel and carbon steel rebars embedded in tensile concrete are reported in expF/bmaxF (A comparison between the modified Danish standard test (tensile concrete) and the standard pull-out test (compression concrete) for carbon steel rebars highlights the fact that the bond strength of a bar anchored in concrete subjected to tensile stresses parallel to the bar is less than the bond strength of a bar anchored in concrete subjected to compression parallel to the bar. In this research, the average of the ratios The analogous comparison in terms of peak slip, The comparison between stainless steel bars and the carbon steel ones shows that the bond stress–slip parameters for the two types of reinforcements are similar; hence, the difference in the material does not significantly affect the bond behavior.For both stainless steel and carbon steel rebars, both the slip corresponding to the peak bond stress and the slope of the bond stress–slip relationship show a dependence on the concrete cover, with the peak slip being lower for the thinnest covers and the slope of the stress–slip curve being steeper. On the whole, a greater cover produces a more ductile behavior.The bond behavior of both stainless steel and carbon steel rebars embedded in concrete subjected to tensile stresses were analyzed by performing a series of 52 tests on specimens and considering the variables of concrete cover, concrete strength, and bar diameter. The authors make the following conclusions.The present study enriches the database of bond tests performed on stainless steel rebars available in the literature and proposes a new bond stress–slip relationship for this type of reinforcement.


Antibiotic use by one individual may affect selection for antimicrobial resistance in close contacts. Here we evaluated whether oral antibiotic treatment of one child within a household affected the gut resistome of an untreated cohabiting child.Households with at least two children <5 y of age were randomized in a 1:1 fashion to a 5d course of azithromycin or placebo. To evaluate indirect effects of azithromycin treatment on the gut resistome, we randomly assigned one child in the house to azithromycin and one to placebo. In placebo households, each child received placebo. We performed DNA sequencing of rectal swabs collected 5 d after the last antibiotic dose. We estimated risk ratios for the presence of genetic resistance determinants at the class level using modified Poisson models for children in azithromycin households compared with placebo households and assessed the composition of the resistome using permutational analysis of variance (PERMANOVA).Of 58 children  with post-treatment rectal swabs, genetic resistance determinants were common but there was no significant difference at the class (p = 0.54 for macrolides) or gene  level between untreated children in azithromycin households compared with placebo households.The results are encouraging that one child's antibiotic use may not influence the resistome of another child.Trial registration:ClinicalTrials.gov NCT03187834. As the gut is the largest reservoir of pathogens in humans, understanding how antibiotic administration affects the resistome in populations is important to predict potential unintended consequences of increasing antibiotic use. Paediatric antibiotic use is increasing in many regions globally.3 Prophylactic mass drug administrations with azithromycin in childhood are being considered in some regions with exceptionally high mortality rates.4 Such programs would almost certainly be targeted to a subset of the population (e.g. preschool children). Analysis of both phenotypic and genotypic resistance following mass drug administration with azithromycin in treated individuals has generally shown increases in macrolide resistance.6 However, whether antibiotic treatment of an individual results in selection for genetic resistance determinants in untreated close contacts is unclear.Antibiotic consumption has been shown to select for antibiotic resistance and lead to expansion of the gut resistome at the individual and community levels.7 However, a study of hospitalized patients showed that antibiotic use by hospitalized patients led to increased risk of Clostridium difficile infection in subsequent occupants of the same bed.8 Transfer of antibiotic resistance genes between cohabiting children could occur via faecal–oral transmission via direct physical contact or shared vectors, such as eating utensils or latrines. The objective of this study was to determine whether antibiotic treatment of one child in a household led to a change in the gut resistome in an untreated cohabiting child compared with the effect of placebo on an untreated child's resistome in a randomized controlled trial of the effects of antibiotic treatment on the gut microbiome.9 We evaluated differences in genetic resistance determinants to macrolides in placebo-treated children in azithromycin- compared with placebo-treated households as well as the resistome in its totality, including specific antibiotic classes and the overall composition of the resistome.Previous work has shown no evidence of an indirect effect of sibling antibiotic use on the composition of the gut microbiome.10 The area is rural and agrarian. Healthcare for children <5 y of age is free in Burkina Faso and delivered via nurse-led primary care clinics. Antibiotic consumption is not uncommon among preschool children and the most commonly prescribed antibiotics are amoxicillin, co-trimoxazole and erythromycin.11This study took place in two communities in the Nouna Health and Demographic Surveillance Site (HDSS) in northwestern Burkina Faso in July 2017.9 Households with at least two children <5 y of age in residence were eligible for inclusion in the study and two children 6–59 months of age were included from each participating household. Eligible households that agreed to participate were randomized in a 1:1:1:1 fashion to a 5d course of amoxicillin, azithromycin, co-trimoxazole or placebo. Within each household, one child was randomized to the household's antibiotic assignment and one child to placebo. In placebo households, both children received placebo, and one child was randomly assigned to serve as the control for the antibiotic-treated child in the antibiotic households and one as the control for the placebo-treated child in the antibiotic households. The present report is limited to children randomized to placebo in azithromycin households and to the placebo-treated child control in placebo households . Samples were collected at the ambient temperature in the field and stored at −80°C in Nouna until they were shipped to San Francisco . Samples were de-identified and processed in a random order. All laboratory personnel were masked to the child and household treatment assignment.2 Briefly, sequencing libraries were prepared using the NEBNext Ultra II DNA Library Prep Kit  and then amplified with 10 polymerase chain reaction cycles. Samples were sequenced on the NovaSeq system  using 150-nucleotide paired-end sequencing. Human sequencing reads were removed and the remaining non-host read pairs were then passed onto Centrifuge (version 1.0.3) to align to the entire National Center for Biotechnology Information non-redundant collection.1 Non-host reads were aligned to the MEGARes reference antimicrobial database using the Burrows–Wheeler aligner with default settings. Only antimicrobial resistance determinants (ARDs) with a gene fraction >80% were identified as present in the sample and included for further analyses.2 Each identified ARD was classified at the class and gene level using the Resistome Analyzer .DNA was extracted using the Norgen stool DNA isolation kit per the manufacturer's instructions. DNA sequencing was performed as previously described.9 A sample size of 30 children per arm was estimated to provide at least 80% power to detect a 1.5-unit difference in Simpson's α diversity. The indirect effect of a cohabiting child's antibiotic treatment on an untreated child was assessed by comparing selection for genetic resistance determinants at both the class and gene levels between placebo-treated children in azithromycin households and placebo-treated children in placebo households. We estimated risk ratios (RRs) for the presence of genetic resistance determinants at the class level using modified Poisson models for children in azithromycin compared with placebo households. As a sensitivity analysis, we included the child's age and recent antibiotic use as covariates in the model. At the class level, we compared post-treatment normalized reads for abundance in children in azithromycin compared with placebo households. To determine the community structure differences, we performed permutational analysis of variance (PERMANOVA) on the L2-norm (Euclidean) distance between treatment groups. Inverse Simpson's diversity was used to evaluate the resistome at the class and gene levels and converted to the effective number per sample. These diversity values can be considered as a measure of the richness of the resistome. A two-sided permutation test on differences in α diversity of the two treatment groups were used for the diversity measures. The number of permutations was 10 000 in all cases. All analyses were conducted in R version 3.4.3 .The sample size was determined based on the primary outcome, which was gut microbial diversity.12 Approximately two-thirds of enrolled children were female and the median age was 20 months . In this study there was a small increase in macrolide resistance in children in households where a cohabiting child had received azithromycin vs placebo, however, this difference was not statistically significant. Therefore this study did not provide evidence that treatment of one child in a household affects the resistome of an untreated child within that household.In this randomized controlled trial, we found no statistically significant evidence that antibiotic treatment of one child leads to an increase in selection for genetic resistance determinants or expansion of the resistome in an untreated cohabiting child. Previous studies of antibiotic use have found evidence of rapid and dramatic expansion of the resistome in treated children.2 A previous analysis found no difference in diversity or composition of the gut microbiome in cohabiting children living with an azithromycin-treated child compared with placebo.7 Taken together, these results do not provide evidence of a spillover effect of azithromycin use on the gut microbiome and resistome.In addition to no significant evidence of selection for genetic resistance determinants at the class level, there was no significant evidence of expansion of the resistome at the gene level. Although azithromycin treatment was previously shown to lead to selection for macrolide resistance determinants compared with placebo, there was no difference in richness in azithromycin-treated children compared with placebo-treated children nor was there a difference in the composition of the genetic resistance determinant.15 and this analysis likely underestimates total transmission of resistance genes between children. This study does not provide data on longer-term spillover effects. Finally, the results of this study are likely not generalizable outside of the study's setting. Results may be affected by background antibiotic use, local pathogenic and commensal bacteria and patterns of interaction between cohabiting children and their environment and therefore may not translate to other settings.This analysis should be considered in the context of several limitations. This study was powered for detection of a direct effect of antibiotic use on the gut microbiome. Any indirect effect of antibiotic use would likely be smaller than a direct effect and thus this study was likely underpowered to detect small differences in the resistome. CIs were fairly wide for most outcomes, and further studies with larger sample sizes are required to evaluate whether there is a small effect of household antibiotic use on the resistome of untreated children. Samples were collected 5 days after the last antibiotic dose. Although treatment itself may rapidly lead to changes in the resistome, indirect effects may take longer to manifest. Macrolide resistance carriage likely persists for >5 d in the gut,In summary, we were unable to detect an indirect effect of paediatric antibiotic use on the resistome of an untreated cohabiting child. These results are encouraging that one child's antibiotic use may not influence the resistome of another child, but the CIs were fairly wide and indicate a lack of precision in the estimates. However, any indirect effect of systemic antibiotic use between children on the paediatric resistome is likely small.


The current study aims at proposing a novel and simple method for designing fluid concrete such as self-compacting concrete (SCC) with a low cementitious binder content to reduce the carbon footprint. Different testing methods regarding the packing density of aggregate mixtures are performed and compared. The W/C was determined according to the target compression strength. Slump flow spread is carried out to determine the most appropriate superplasticizer (SP) dosage and aggregate volume fractions and proportions in concrete mixtures. Furthermore, hardened performance, including compression strength and drying shrinkage of the fluid concrete, are characterized. Finally, a mix design process of fluid concrete with low cement content was proposed based on the preferred fresh and hardened properties of the concrete mixtures. Since the 1980s, construction projects have placed increasing demands on the workability of concrete. The ever-increasing complexity of the construction elements led to the difficulty of the implementation of the traditional vibrating technology, which further led to serious durability problems due to the lack of the compaction of the fresh concrete. In the meantime, the noise and interference generated during the construction of traditional vibrating concrete seriously affected the normal lives of surrounding residents. In order to solve these dilemmas, a flowable concrete, which was later named self-compacting concrete (SCC), was designed by Okamura et al. . The idea behind this novel type concrete is to reduce the size and the amount of the coarse aggregates and to increase the powder and paste content in the mixture. Meanwhile, high-range water-reducing agent is required to achieve a high flowability of the interstitial cement paste while maintaining a high content of powders to provide a decent flowability for fresh fluid concrete ,3,4,5.Nevertheless, due to the high content of powders in SCC mix proportion, the ensuing problems are high hydration heat generated during setting and high autogenous deformation compared to the traditional vibrating concrete ,7,8,9. TIn recent years, many studies have focused on reducing the amount of cementitious materials used in fluid concrete ,17,18,19The current study aims at proposing a novel method for designing the fluid concrete such as SCC with low cementitious binder content. Three types of packing density including the loose packing density, the vibrating density, and the compaction packing density are first carried out to determine the optimum aggregate proportioning range of binary and trinary aggregate mixtures. Slump flow spread at various age of fresh concrete mixtures containing different dosage of superplasticizer (SP) is then measured to determine the most appropriate SP dosage in concrete mixtures. After that, the fluid concrete with different aggregate volume fractions in mix proportion and fine aggregates to coarse aggregates ratio  are fabricated to measure the hardened performance, including compression strength and drying shrinkage. Finally, an overall design process of low cementitious binder content fluid concrete is proposed.3 was used in this study. The filler used in this study is milled limestone with apparent density of 2700 kg/m3. The median particle size  of cement powder and filler powder are around 9 and 15 μm, respectively. River sand with apparent density of 2600 kg/m3 was used. The particle size distribution of cement powders, filler powders, and sand particles measured by a laser particle size analyzer are shown in 3 were used. The size of the coarse gravel is 5–10 mm and the size of the fine gravel is 10–20 mm.A CEM I 52.5 N type of cement with apparent density of 3100 kg/mTap water was used as the mixing water. A polycarboxylate-type of SP with solid content of around 20% was used to adjust the flowability of the fresh concrete mixtures.The binary aggregate mixture contains coarse gravels and fine gravels while the trinary aggregate mixture contains two sizes of gravels and sand, first manually mixed for 5 min to achieve a relatively homogeneous distribution.For the loose packing density measurement, the aggregates were slowly added into a cylindric container with the volume of 7 L (both 207 mm in diameter and in height). The aggregates were slowly filled into the container with a dumping height of 50 mm to the stacked surface. Finally, the conical aggregate pile on the top of the container was gently flattened by a rod. The mass of the aggregates in the container was recorded at the end of the test.For the vibrating packing density measurement, the container was placed on a vibrating table with the amplitude of around 1 mm and the frequency of around 50 Hz. The aggregates were slowly added to the container that is the same as the one for the loose packing density measurement. The procedures were kept the same as the loose packing density measurement. The mass of the aggregates in the container was recorded at the end of the test.The dense packing density of aggregates was also performed using a 76-B2522 portable Gyratory Compactor . The size of the container was 150 mm in diameter. 4 kg of the manually pre-mixed aggregates were filled in the container. The shear strength ranges from 200 kPa to 600 kPa were selected to determine the effect of applied strength on the packing density of aggregates. The gyratory angle, the rotation rate, and the cycle number were set as 1.16°, 30 rpm, and 500, respectively ,14. The The packing density of aggregates mixtures performed with above three methods were computed through dividing the mass of the aggregates by the volume of the aggregates that occupied in the container. The void fraction gregates .A single-horizontal-shaft forced type of concrete mixer with mixing capacity of 60 L was used to prepare the fresh concrete mixtures. The preparation of the fresh concrete mixtures lasted in total 5 min. Dry powders and aggregates were first mixed in the mixer for 1 min. The water pre-mixed with SP was then added to the mixer and mixed for 2 min. After that, the mixer was stopped and the mixture that attached on the mixing vane was scraped in 0.5 min. Finally, the mixer was restarted for another 1.5 min.Slump flow measurement was performed using a concrete slump cone according to the ASTM C1611 . The flo3. The samples were demolded at 1 d, and then were transferred in the standard steam curing room with the temperature of 20 ± 2 °C and the relative humidity of around 98% until the testing age . The compression strength of the hardened concrete samples was carried out using a universal compression machine with the maximum loading capacity of 3000 kN. The loading rate was set as 5 kN/s.Fresh concrete mixtures were cast into the mold with the dimension of 100 × 100 × 100 mm3 and with an embedded copperhead in the center of one end of the mold. The samples were demolded at 1 d and then cured in the standard steam curing room at the temperature of 20 ± 2 °C and the relative humidity of around 98% for 2 days. The hardened prisms were then placed on a micrometer stand equipped with a micrometer with the measurement accuracy of ±0.001 mm. The drying deformation measurement was performed at the ambient temperature of 20 ± 2 °C and the relative humidity of around 55 ± 5%.Fresh concrete mixtures were cast into the mold with the dimension of 100 × 100 × 515 mmThe influence of shearing cycle on bulk density of coarse gravels measured by the Gyratory Compactor is first checked and shown in The powder content  and void fraction of coarse gravels are plotted in As a typical optimization packing model, Fuller model denotes the optimum gradation of aggregate in concrete mixture design :(2)Pd= value is determined according to the Abrams’ law (Cf. Equation (5)) ,29.(5)fThe impact of SP on flowability of concrete mixtures at fresh state is first studied based on one of the optimum proportions of sand-gravel mixtures. For the representative concrete mixture, the aggregate volume fraction in concrete mixture is set as 62.5%, the sand volume ratio in total aggregate mixtures is set as 53.0%. Five dosages of SP in concrete mixtures were studied and the slump flow of fresh concrete mixtures at different time after mixing is presented in It can be seen from Moreover, as seen in It can be seen in In the case of varying sand to total aggregate volume ratio, it is seen from Determine the optimum packing of aggregate mixtures: Either the loose packing or the dense packing method can be applied to determine the range of the optimum proportion of fine aggregates (sands) and coarse aggregates (stones).Determine the maximum aggregate content: Based on the dense packing density, the maximum aggregate content can be estimated according to the rheology deviation packing fraction in Chateau-Ovarlez model (Cf. Equation (4)) ,26.Determine the W/C in concrete mixtures: Based on the Abrams’ law (Cf. Equation (5)) ,29, the Determine the SP dosage: The proper dosage of SP can be acquired by a few batches of trial to meet the required flowability  and lower shrinkage  shall be preferred.Based on the experimental results and analysis carried out in the current study, a design process of low cement content fluid concrete  can be summarized in the following steps:It should be noted that, indeed, the Abrams law applied in the above mix design approach was only validated for the cement clinker . HoweverIn addition, in order to further guarantee the hardened properties such as the mechanical strength and shrinkage, a few more mix designs can be studied including using less filler in powder mixture or decreasing water to powder ratio to increase the hardened strength, as well as adding shrinkage-reducing admixtures to reduce the shrinkage of hardened concrete.It is summarized that by combining the packing measurement with the Chateau-Ovarlez model, the design process of fluid concrete with paste content can be achieved. Based on existing concrete raw materials, one can efficiently locate the optimized ratio of different aggregates by simply carrying out any types of packing density measurements. The amount of aggregates that diverges the rheological behavior can also be rapidly located according to the Chateau-Ovarlez model. Finally, only a few batches are needed to verify the aggregate amount in the concrete mix proportion to meet the flowability that the fresh concrete required.In the current work, a novel and simple method for designing the fluid concrete such as SCC with low cementitious binder content was carried out. Various testing methods regarding packing density were performed and compared to determine the optimum aggregate proportioning range and maximum content of aggregates in concrete mixtures. A medium strength grade concrete was designed and the W/C was determined according to the Abrams’ law. The slump flow spread at various ages of fresh concrete mixtures containing different dosages of SP was then measured to determine the most appropriate SP dosage in concrete mixtures. Furthermore, the flowability of fluid concrete with different aggregate volume fractions and sand ratios were carried out and the fresh concrete mixtures were also fabricated to measure the hardened performance, including compression strength and drying shrinkage. Finally, a mix design process of fluid concrete with low cement content was proposed based on the preferred fresh and hardened properties such as flowability, slump flow loss, mechanical strength, and dry shrinkage carried out in the current work. It includes the following five steps: Determine the optimum packing of aggregate mixtures; determine the maximum aggregate content; determine the W/C in concrete mixtures; determine the SP dosage; finalize the aggregate volume fraction and sand to total aggregate ratio.