# Mechanical Properties of Desert Sand-Based Fiber Reinforced Concrete (DS-FRC)
## 2 Experimental Program
### Mix Proportions and Material Properties
The constant volumes of fly ash about 60% and PVA fiber about 2% by volume were used to prepare the FRC, and the change ranges of W/B, S/B and DSRR were 0.26-0.29-0.32-0.35, 0.30-0.36-0.42, 40%-60%-80%-100%, respectively. The mixture proportions of components are listed in Table 3.  
In order to control the fluidity of DS-FRC, the fiber was added before the superplasticizer in this test, which was different from the traditional preparation method of high ductility cementitious composites. It was difficult to obtain good fiber dispersion properties if the superplasticizer was added in advance. The phenomenon of fiber floating with large content of superplasticizer would be observed, limiting the development of material properties of DS-FRC. A forced pre-wet mixer was used to prepare the DS-FRC. First, the raw materials were mixed for 2 minutes at low speed, following the order of fly ash, cement, desert sand and river sand. Then, the water was added slowly along the mixer's wall for about 2 minutes at high speed. Subsequently, dispersed fibers were incorporated rapidly along the mixing direction for another 2-3 minutes at low speed. Finally, a constant volume of superplasticizer with 0.05% of cementitious materials was added. In order to improve the mixing efficiency, it was added with a frequency of 0.5 g/s until the mixture was evenly dispersed without cluster. It took about 10-12 minutes for the whole mixing process. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline Mix NO. & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8** & **9** & **10** \\ \hline
**W/B** & 0.26 & 0.29 & 0.32 & 0.35 & 0.29 & 0.29 & 0.29 & 0.29 & 0.29 & 0.29 \\
**S/B** & 0.36 & 0.36 & 0.36 & 0.36 & 0.30 & 0.42 & 0.36 & 0.36 & 0.36 & 0.36 \\
**DSRR** & 40\% & 40\% & 40\% & 40\% & 40\% & 40\% & 40\% & 60\% & 80\% & 100\% & 40\% \\
**Cement** & & & & & & & & & & & \\ kg/m\({}^{3}\) & 550.22 & 541.35 & 532.47 & 514.72 & 559.10 & 514.73 & 541.35 & 541.35 & 541.35 & 541.35 \\
**Fly ash** & & & & & & & & & & \\ kg/m\({}^{3}\) & 825.33 & 812.02 & 798.71 & 772.09 & 838.64 & 772.08 & 812.02 & 812.02 & 812.02 & 812.02 \\ Water & & & & & & & & & & \\ kg/m\({}^{3}\) & 357.64 & 392.48 & 421.54 & 450.38 & 399.35 & 377.17 & 392.48 & 392.48 & 392.48 & 392.48 \\
**River sand** & & & & & & & & & & \\ kg/m\({}^{3}\) & 292.86 & 292.33 & 287.53 & 277.95 & 252.92 & 332.80 & 194.88 & 97.44 & 0 & 292.33 \\
**Desent sand** & & & & & & & & & & \\ kg/m\({}^{3}\) & 195.24 & 194.88 & 191.68 & 185.30 & 168.61 & 221.86 & 292.33 & 389.77 & 487.21 & 194.88 \\
**PVA fiber** & & & & & & & & & & \\ kg/m\({}^{3}\) & 26 & 26 & 26 & 26 & 26 & 26 & 26 & 26 & 26 & 26 \\
**Superplasticizer** & & & & & & & & & & & \\ kg/m\({}^{3}\) & 0.78 & 0.77 & 0.75 & 0.73 & 0.79 & 0.73 & 0.77 & 0.77 & 0.77 & 0 \\
**Density** & & & & & & & & & & & \\ kg/m\({}^{3}\) & 1949.5 & 1949.2 & 1874.0 & 1815.8 & 1910.5 & 1918.8 & 1859.5 & 1853.4 & 1861.9 & / \\
**Consistency** & & & & & & & & & & & \\ mm & 35 & 74 & 78 & 133 & 74 & 70 & 59 & 67 & 63 & 66 \\
**Elastic Modulus** & & & & & & & & & & & \\
**GPa** & / & 19.16 & / & / & 18.31 & 18.39 & 19.28 & 17.31 & 13.13 & / \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Mixture proportion of desert sand-based fiber reinforced concrete (DS-FRC). The specimens for uniaxial tensile/compression testing were prepared by directly pouring the mixture into steel molds. It was noted that the compression cylindrical specimens with a size of \(\phi\) 75 mm \(\times\) 150 mm (diameter \(\times\) height) were cast in two layers for good compactness, and slight insertion and vibration for about 10-12s was used after each time. However, the tensile dumbbell-type specimens with the size of 330 mm \(\times\) 60 mm \(\times\) 13 mm (length \(\times\) wide \(\times\) thickness) were cast in only one layer with the vibration time of about 10-12s. Subsequently, the cast process of DS-FRC was completed by smoothing the surface of specimens.