Hu Panzhi^1，2， Yang Jiansen¹， Lian Zeli¹

^{1.School of Civil and Hydraulic Engineering， Ningxia University， Yinchuan 750021， China； 2.Zhongning County Farmland Construction Service Center， Zhongwei 755100， China}

Abstract

Objective This study aims to investigate the mechanism by which the water-to-binder ratio （the mass ratio of water to cementitious materials） and the micro-aggregate effect of desert sand influence the mechanical properties and cement hydration process of desert sand mortar， and to establish a nondestructive testing model for the compressive strength of desert sand mortar using the ultrasonic-rebound combined method. Furthermore， the strength enhancement mechanism is elucidated from the perspectives of the micro-aggregate filling effect and the crystal nucleus effect， providing theoretical basis and practical reference for the resource utilization of desert sand， the optimization of mortar performance， and nondestructive engineering testing.

Methods The water-to-binder ratios were set at 0.33~0.67， and 14 groups of 70.7 mm×70.7 mm×70.7 mm cubic mortar specimens were prepared， with three specimens cast under each condition. After curing in a standard curing room for 28 days， nondestructive testing analyses were conducted on the desert sand mortar （DSM） specimens. Normal mortar （NM） was prepared as a control group at water-to-binder ratios of 0.33， 0.39， 0.47， and 0.62. The rebound method and the ultrasonic pulse velocity method were employed for nondestructive testing on both DSM and NM under different water-to-binder ratios. A double power function model （D=5.503m^0.681n^-0.561） correlating compressive strength （D） with rebound value （m） and ultrasonic wave velocity （n） was established. The applicability of the model was verified via the runs test at the α=0.05 significance level. Additionally， the influence mechanism of the water-to-binder ratio on the compressive strength of DSM was analyzed through hydration heat and scanning electron microscope （SEM） tests， and the micro-aggregate effect and crystal nucleus effect of desert sand particles were explored.

Results The compressive strength was found to decrease with an increase in the water-to-binder ratio. As the water-to-binder ratio increased from 0.33 to 0.67， the 28-day compressive strength of DSM decreased from 52.84 MPa to 22.74 MPa， representing a reduction of approximately 57.0%. Under identical water-to-binder ratios， the compressive strength of DSM was significantly higher than that of NM， with increases of approximately 25.2%， 26.9%， 39.8%， and 11.0%， respectively. Moreover， the double power function relationship between compressive strength， rebound value， and ultrasonic wave velocity was shown to be significant at the α=0.05 level through regression analysis， indicating that the compressive strength of DSM could be accurately predicted and evaluated. It was also revealed that the fine particle size and well-graded nature of desert sand effectively improved the compactness of the paste and promoted early cement hydration.

Conclusion It is concluded that the correlation coefficients of the independent models relating compressive strength to either rebound value or ultrasonic wave velocity are lower than that of the ultrasonic-rebound combined model. Therefore， the evaluation of DSM compressive strength via the ultrasonic-rebound combined method is more precise. The goodness-of-fit for the double power function combined model reaches R²=0.975， with a root mean square error of 0.792 MPa， demonstrating that the compressive strength of DSM can be accurately predicted. The water-to-binder ratio is identified as the critical factor affecting the compressive strength of DSM. Under identical water-to-binder ratios， the overall compressive strength of DSM with good workability is higher than that of NM. The fine particles of desert sand exhibit both a “ball-bearing” micro-aggregate filling effect and a crystal nucleus effect. Their fine particle characteristics facilitate the filling of micro-pores between the paste and aggregates， optimize particle packing， and enhance the structural compactness of the mortar. Meanwhile， these particles provide nucleation and growth sites for hydration products， reduce the nucleation barrier of cement hydration crystals， and promote early cement hydration， thereby increasing the compressive strength of DSM.

Keywords： desert sand mortar； compressive strength； nondestructive testing； micro-aggregate effect； hydration heat

Get Citation:Hu Panzhi， Yang Jiansen， Lian Zeli. Study on compressive strength of desert sand mortar based on nondestructive testing［J］. China Powder Science and Technology， 2026， 32（5）： 1-12.

Received:2026-02-03， Revised： 2026-03-28， Online： 2026-08-网上出版日期:19。

Funding： This research was supported by the National Natural Science Foundation of China (Grant No. 52368038).

CLC No.:TB4； TU528.01

Type Code:A

Serial No.:1008-5548（2026）05-0001-12