Currently, fire in building is one of the most serious disasters. With the increase of basic construction items in western China, ordinary medium sand resource no longer met with the need of engineering. Compressive strength experiments of concrete produced with desert sand after elevated temperature were carried out in this paper. The effects of desert sand replacement rate (DSRR), temperature and cooling regime on the mechanical performances of concrete produced with desert sand were analyzed. XRD and SEM experiments were also conducted to study the microstructure of concrete produced with desert sand after elevated temperature. Experimental results showed that the cubic compressive strength of concrete produced with desert sand increased firstly, and then declined with temperature. Whereas, the prismatic compressive strength and elasticity modulus of concrete produced with desert sand under static compression declined with temperature. With the enhancement of DSRR, the elasticity modulus under static compression, cubic compressive strength and prismatic compressive strength of concrete produced with desert sand after elevated temperature increased firstly, and then declined, the maximum value of which was reached when DSRR amounted to 40%. Regression models were established to predict the mechanical performances of concrete produced with desert sand after elevated temperature, which were in good agreement with experimental results.

This paper presents the study on the properties of high-ductility fiber reinforced concrete made with desert sand from China’s Mu Us desert. The workability and uniaxial tensile/compression properties of undisturbed desert sand-based fiber reinforced concrete (DS-FRC) with the change of water-to-binder ratio (W/B), sand-to-binder ratio (S/B) and desert sand replacement rate (DSRR) were experimentally investigated. Experimental results reveal that the appropriate W/B and desert sand content are conducive to the workability development of DS-FRC. The uniaxial tension/compression properties of DS-FRC are mainly affected by the W/B. Especially, the highest uniaxial tensile/compression stresses and corresponding strains are obtained at the W/B of 0.29. The S/B has similar effects on the uniaxial tensile/compression properties, and an S/B of 0.36 is the optimal ratio. In terms of the DSRR, it shows less effect on the uniaxial tensile/compression properties, even for the DSRR of 100%. The results of the tests indicate that undisturbed desert sand can be used as silica sand in high-ductility fiber reinforced concrete.

At present, the exploitation of river sand is forbidden because of the harm to the environment. The production processes of microsilica sand are complicated and the cost is high. The excellent availability of desert sand provides a practical solution for using it as the aggregate, this research used high-volume fly ash, steel fiber, PVA fiber and some or all of the Mu Us desert sand to replace the river sand to prepare the Desert-Sand-based steel-PVA hybrid Fiber Reinforced ECC (H-DSECC) that meets the performance requirements. Through the single factor test, the steel fiber replacement rate and the desert sand replacement rate were taken as the main factors, and the mechanical properties of H-DSECC were initially explored. The results show that the high steel fiber replacement rate or high desert sand replacement rate is not conducive to the realization of strain-hardening. An H-DSECC mixture containing 40% desert sand with W/B ratio of 0.29 has delivered the best properties with the tensile strain capacity of 1.467%, the tensile strength is 7.5 MPa and the cylinder compressive strength is 41.03 MPa at 28 days. Based on the measured stress-strain curves, the uniaxial tension/compression stress-strain curve equations are proposed.

Demand for medium sand has increased greatly with increasing infrastructure construction items. The shortage of construction sand resources has become a serious problem in many districts. It not only increases the engineering cost, and the overexploitation of river sand and mountain as medium sand also brings a series of serious environment problems. There are abundant desert sand (DS) resources in western China. If DS resources can be used to substitute medium sand to produce desert sand concrete (DSC), which was suitable for engineering practice, the environment can be improved and engineering cost can be reduced. Although many researchers had focused on the mechanical performance of DSC, there were few documents on the frost resistance of DSC. Frost resistance experiments of DSC with 50% desert sand replacement ratio (DSRR) and ordinary concrete (OC) were performed in this paper. Influence of freeze‐thaw cycles on the mechanical properties of OC and DSC was analyzed. Experimental results showed that, with increasing freeze‐thaw cycles, the damage, peak strain, and porosity increased, while elastic modulus, Poisson′s ratio, and peak stress declined, the stress‐strain curves tended to be flat. Under the same condition of freeze‐thaw cycles, the frost resistance of DSC with 50% DSRR was higher than that of OC. Constitutive model of DSC after different freeze‐thaw cycles was formulated. The results predicted by constitutive model agreed well with experimental results, which can provide technical support for DSC engineering practice.

Building fires and shortage of medium sand resources have become two major issues in building domain. Desert sand was used to produce desert sand concrete (DSC), which was suitable for engineering utility. The mechanical properties tests of DSC with different desert sand replacement ratio (DSRR) were carried out after elevated temperature. The effects of elevated temperature and DSRR on DSC mechanical properties were analyzed. DSC microstructure was investigated by SEM and XRD. Research studies’ results showed that the relative compressive strength increased gradually with increasing temperature. The maximum value appeared at 200°C–300°C, and it began to decrease at 500°C. Compared with room temperature, the compressive strength at 700°C was about 70% of that at room temperature. Relative splitting tensile strength increased first and then decreased, and the value reached the maximum at 100°C. DSC relative flexural strength decreased with the temperature. Relative compressive strength, splitting tensile strength, and flexural strength of DSC enhanced first and then decreased with DSRR, and the maximum values were obtained with 40% DSRR. Based on the regressive analysis, the relative compressive strength was a quadratic polynomial with relative porosity. Relative splitting tensile strength and relative flexural strength were linear with relative porosity. Research results can provide the technical support for DSC engineering application and postfire assessment.

Ningxia is located in the western part of China, which abounds with desert resources. The application of desert sand in concrete has not been fully studied. In order to study the failure mechanism of desert sand concrete under impact loading, dynamic impact experiments on desert sand concrete and ordinary concrete were carried out by using the 74 mm diameter split Hopkinson pressure bar (SHPB) experimental apparatus. The dynamic mechanical properties of desert sand concrete under different impact velocities were analyzed. The random distribution program of round coarse aggregate in desert sand concrete was designed to generate the random distribution of coarse aggregate by ANSYS/APDL language. The dynamic failure process of single-graded concrete and two-graded concrete was numerically simulated and compared. The results showed that desert sand concrete and ordinary concrete have obvious rate-dependent effect. Detailedly, the ordinary concrete is totally destroyed when impact velocity is 10 m/s, but the desert sand concrete still maintains the cone shape at impact velocity of 18 m/s, which indicates that the impact resistance of desert sand concrete is better than that of ordinary concrete. When impact velocity is 5 m/s, the single-graded concrete and two-graded concrete are both destroyed, but the desert sand concrete is not damaged. When impact velocity is 10 m/s, the dynamic failure mode of single-graded concrete, two-graded concrete, and desert sand concrete is basically the same. When impact velocity is 15 m/s, the single-grade concrete shows different dynamic failure mode from that of desert sand concrete and two-graded concrete.