# Mechanical Properties of Desert Sand-Based Fiber Reinforced Concrete (DS-FRC)
## 3 Results and Discussion
### Uniaxial Tensile Properties of DS-FRC
#### 3.3.2 The Strength Development and Stress-Strain Curves  
The mechanical parameters of DS-FRC under the uniaxial tensile test are shown in Table 4. Tensile stress-strain curves of DS-FRC and counterparts without the superplasticizer are presented in Figures 4 and 5. In this experiment, the uniaxial tensile properties of DS-FRC were not comparable to that of typical because the particle size of sand used in this experiment was larger than that of high ductility cementitious composites, which caused relatively poor tensile strain hardening response. Figure 3: The failure mode of specimens under uniaxial tensile test: (a) the partial magnification of multiple cracks; (b) the crack space of multiple cracks. However, it has been proved that FRC with only 1% tensile strain and relatively poor tensile strain hardening properties could still show good structural applicability [57; 58; 59; 60; 61]. When it is applied to structure, such as coupling beams, columns and shear walls, good tensile/shear ductility, high flexural toughness and high energy consuming properties will be obtained. Therefore, the DS-FRC prepared in this experiment is anticipated to achieve good engineering application. The results of the uniaxial tensile properties of DS-FRC are as follows. The initial cracking stress, the initial cracking strain, the ultimate tensile stress and corresponding strain with different mixtures are presented in Table 4. With the increase of W/B, the initial cracking stress first increased and then decreased. The maximum value was obtained at the W/B of 0.29. Besides, the higher tensile initial cracking stresses were, the higher corresponding strains were. The DS-FRC without superplasticizer showed higher initial cracking stress and lower initial cracking \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
**Tensile Initial Cracking Stress (MPa)** & 2.20 & 2.95 & 1.85 & 0.99 & 2.04 & 2.00 & 1.96 & 2.08 & 2.04 & 4.20 \\
**Tensile Initial Cracking Strain (\%)** & 0.07 & 0.07 & 0.07 & 0.04 & 0.03 & 0.04 & 0.06 & 0.06 & 0.05 & 0.03 \\
**Ultimate Tensile Stress (MPa)** & 4.01 & 5.42 & 3.83 & 2.71 & 5.01 & 4.61 & 4.65 & 3.79 & 4.78 & 7.25 \\
**Ultimate Tensile Strain (\%)** & 3.63 & 3.50 & 1.44 & 2.77 & 3.32 & 4.43 & 3.68 & 1.87 & 1.57 & 0.7 \\
**Ultimate Compression Stress (MPa)** & 46.3 & 43.3 & 35.1 & 31.4 & 4.05 & 39.9 & 40.5 & 40.4 & 36.8 & 40.2 \\
**Ultimate Compression Strain (\%)** & 1.17 & 1.08 & 1.26 & 1.06 & 1.13 & 1.36 & 1.00 & 1.37 & 1.19 & 0.97 \\ \hline \hline \end{tabular}  
* Tensile cracking point: The proportional limit point of the tensile stress–strain curves.  
\end{table} 
Table 4: Basic properties of DS-FRC. Figure 4: The effect of different factors on the ultimate tensile/compression stress: (**a**) W/B; (**b**) S/B; (**c**) DSRR; (**d**) with or without superplasticizer (SP). strain than that with superplasticizer. It may be attributable to the nature of the superplasticizer, which is beneficial to the development of strength while it weakens the strain. With regards to the ultimate tensile stress and the corresponding strain, it was observed that the ultimate tensile stress of DS-FRC was significantly higher than the initial cracking stress regardless of mixtures. As is shown in Figures 4a and 5a, the ultimate tensile stress first increased then decreased while the corresponding strain gradually decreased overall with the increase of W/B. The optimal mechanical properties were observed at the W/B of 0.29 with the ultimate tensile stress of 5.42 MPa and the corresponding strain of 3.50%. The ultimate tensile stresses showed a similar trend where the increase of S/B and the comparable ultimate tensile strains were obtained, as is revealed in Figures 4b and 5b. The optimal mechanical properties were observed at the S/B of 0.36. According to the Figures 4c and 5c, the DSRR showed a relatively small effect on the ultimate tensile stress of DS-FRC, even for the DSRR of 100%.