# Analysis of the Aggregate Effect on the Compressive Strength of Concrete Using Dune Sand
## 2 Experimental Plan and Method
### Materials and Mixture Proportions  
To conduct concrete experiment, DS and CS, which were core materials for the research purpose, were imported from the Middle East. Other concrete materials were produced in Korea.  
Table 1 lists the materials used in this study, along with their physical properties. In this study, limestone-based CS and coarse aggregate were used, and the main chemical components of DS is shown in Table 2.  
Figure 1 shows the particle-size distribution curves for CS, DS, and binary sands with different DS replacement ratios. Figure 1 shows that CS and DS could not meet the standard particle size distribution for FA defined in the KS F 2526 standard [17] (ASTM C 33 [18]). Furthermore, binary sand could not meet the standard particle size distribution; however, its particle size distribution was close to that defined in the standard. Moreover, the fineness modulus (FM) values for CS and DS, which were 3.6 and 0.7, respectively, are not within the standard FM range of 2.3-3.1 as defined in the KS 2526 standard [17] (ASTM C 33 [18]). In contrast, the FMs of binary sand with 20 and 40% DS replacement ratios were 3.02 and 2.44, respectively, which are within the standard FM range.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Material** & **Physical Properties** \\ \hline \multirow{4}{*}{Cement} & • Ordinary Portland cement (OPC) \\  & • Density: 3.15 g/cm\({}^{3}\) \\  & • Fineness: 3440 cm\({}^{2}\)/g \\ \hline \multirow{4}{*}{CA} & • Coarse aggregate \\  & • Maximum size: 20 mm \\  & • Density: 2.70 g/cm\({}^{3}\) \\  & • Absorption ratio: 0.77\% \\ \hline \multirow{4}{*}{CS} & • Maximum size: 5 mm \\  & • Density: 2.61 g/cm\({}^{3}\) \\  & • FM: 3.6 \\  & • Absorption ratio: 1.53\% \\ \hline \multirow{4}{*}{DS} & • Density: 2.61 g/cm\({}^{3}\) \\  & • FM: 0.7 \\  & • Absorption ratio: 1.19\% \\ \hline \multirow{4}{*}{Admixture} & • Naphthalene based \\  & • Density: 1.23 g/cm\({}^{3}\) \\  & • pH: 6.79 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Materials used in this study and their physical properties.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Chemical** & **SiO2** & **CaO** & **Al2O3** & **MgO** & **Fe2O3** & **K2O** \\ \hline \% & 47.1 & 38.8 & 5.65 & 3.03 & 2.68 & 1.44 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Chemical composition of DS.  
Table 3 lists the proportions of the different concrete mixtures used in this study. For the experiments, the sand-to-aggregate (s/a) ratio and the chemical admixture (AD) content were set as per the target slump. During experimental mixing, an attempt was made to obtain a concrete mixture using only CS; however, the target slump could not be attained, even though the s-a ratio and AD content were increased. Nevertheless, when at least 10% DS was substituted instead of CS, it was possible to derive concrete mixtures that met the target slump. In addition, even in the case of binary sand with a 10% DS/FA ratio, the target slump could not be met when the water content of the concrete mixture was less than 150 kg/m\({}^{3}\). In contrast, when binary sand with a 20% DS/FA ratio was used, the target slump could be attained with a water content of 150 kg/m\({}^{3}\) in the concrete mixture.