PurposeThe purpose of this study was to explore the inhibitory effect of quartz sand particle size and incorporation on soil desiccation cracks.MethodsThree sets of red soil samples with quartz sand of different contents and particle sizes were used to evaporation test to analyze the evaporation process and observe the initiation and propagation of desiccation cracks; the software named Pore and Cracks Analysis System (PCAS) was used to quantitatively analyze geometric features of cracks, including surface crack ratio (Rsc), average length (Lave), and average width (Wave); the scanning electron microscope (SEM) was employed to investigate the inhibitory mechanisms of quartz sand on desiccation cracking of red soil.ResultsThe results revealed that the addition of quartz sand increased the surface roughness and actual evaporation area, thereby improving the steady-state evaporation rate. The higher content of quartz sand (particle size equivalent to soil particles), the lower Rsc, Lave, and Wave, which can be attributed to the improvement of soil skeleton strength and fracture resistance, as well as the reduction of tensile load caused by capillary tension. Compared to fine-grained quartz sand, the interface effect and low friction between coarse-grained quartz sand and soil particles promote crack propagation, weakening the inhibitory effect of quartz sand on red soil cracking.ConclusionThese results indicate that the addition of quartz sand can effectively suppress soil cracking, and fine particles and high dosage have better inhibitory effects on soil cracking, which offers a practical reference for mitigating macroscopic cracking in arid regions of northwest China.