# Analysis of the Aggregate Effect on the Compressive Strength of Concrete Using Dune Sand
## 3 Results and Discussion  
### Slump  
Figure 2 shows the measured slump of each concrete mixture used in the study, and Figure 3 shows the AD contents that were used to attain the target slump. For the same water content, the change in AD content due to an increase in the DS replacement ratio was small. In contrast, for a constant DS replacement ratio, the AD content required to attain the required slump increased as the water content decreased. In particular, when the water  
Figure 1: Particle-size distributions of the FAs used in this study. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Mixture a**} & \multirow{2}{*}{\
\begin{tabular}{c} **Slump** \\ **(mm)** \\ \end{tabular} } & \multirow{2}{*}{**W/C**} & \multirow{2}{*}{**s/a**} & \multicolumn{6}{c}{**Unit Weight (kg/m\({}^{3}\))**} & \multirow{2}{*}{
\begin{tabular}{c} **AD** \\ **(cw\%)** \\ \end{tabular} } \\ \cline{5-10}  & & & & & **W b** & & **C c** & & **CS** & **DS** & **CA** & **(cw\%)** \\ \hline \multirow{3}{*}{W170} & DS10 & & & 0.60 & 170 & 425 & 951 & 106 & 729 & 0.8 \\  & DS20 & & & 0.50 & 170 & 425 & 705 & 176 & 911 & 0.8 \\  & DS40 & & & 0.45 & 170 & 425 & 476 & 317 & 1002 & 0.7 \\  & DS60 & & & 0.40 & 170 & 425 & 282 & 423 & 1094 & 0.8 \\ \hline \multirow{3}{*}{W160} & DS10 & \multirow{3}{*}{\(\pm\) 25} & \multirow{3}{*}{0.4} & 0.65 & 160 & 400 & 1058 & 118 & 655 & 1.0 \\  & DS20 & & & 0.55 & 160 & 400 & 796 & 199 & 842 & 1.0 \\  & DS40 & & & 0.45 & 160 & 400 & 488 & 326 & 1029 & 1.0 \\  & DS60 & & & 0.42 & 160 & 400 & 304 & 456 & 1085 & 1.1 \\ \hline \multirow{3}{*}{W150} & DS20 & & 0.60 & 150 & 375 & 891 & 223 & 768 & 1.2 \\  & DS40 & & & 0.48 & 150 & 375 & 534 & 356 & 998 & 1.5 \\ \cline{1-1}  & DS60 & & & 0.43 & 150 & 375 & 319 & 479 & 1094 & 1.3 \\ \hline \hline \end{tabular}  
* \({}^{\text{a}}\) W170 = Water content 170 kg/m\({}^{3}\), DS10 = DS/FA ratio 10%. b W: Water. c C: Cement.  
\end{table} 
Table 3: Proportions for the different concrete mixtures used in this study. content in the concrete mixture decreased from 170 to 160 kg/m\({}^{3}\), the required AD content increased by 25-43%; whereas, when the water content decreased from 160 to 150 kg/m\({}^{3}\), the AD content increased by 18-20%. For constant water-cement ratios and water contents, all of the mixtures had the same cement paste and aggregate contents. Nevertheless, while the total aggregate volume remained the same, the volume of each aggregate type was different, which affected the workability of the resulting concrete [10]. This indicates that the fluidity improvement effect of an AD may vary depending on the volume fraction of the aggregate, even though the same AD content was used. In this study, the slump values per unit AD content (slump to AD ratio, slump/AD ratio) of all the concrete mixtures were calculated and compared. Based on our observations, we determined that high slump/AD ratios can maximize the fluidity improvement effect of the AD in a concrete mix, indicating that such conditions are favorable for improving the workability of the concrete. Figure 4 shows the slump/AD ratio results for the different concrete mixtures used in this study. Figure 3: Admixture (AD) contents of the concrete mixtures used to attain the target slump. Figure 2: Particle-size distributions of the FAs used in this study. Among the W170 mixtures, the DS10 mixture had the smallest slump/AD value of 225 mm/%. Furthermore, the slump/AD ratio increased as the DS/FA ratio increased to 40% (i.e., DS40); however, it decreased for DS60. The highest slump/AD ratio (250 mm/%) was obtained for the DS40 mixture, which was approximately 11% higher than that of the DS10 mixture. Among the W160 mixtures, the lowest slump/AD ratio was 159 mm/% for the DS60 mixture, whereas the highest slump/AD ratio (195 mm/%) was observed in the case of the DS40 mixture, which was approximately 23% higher than that of the DS60 mixture. Furthermore, among the W150 mixtures, the highest slump/AD ratio (158 mm/%) was observed in the case of the DS40 mixture.