Characteristics of Hydration Products and Multifactor Regression Analysis of Compressive Strength of Aeolian Sand Concrete at Different Ages

To alleviate the shortage of natural river sand and promote the utilization of aeolian sand, concrete was prepared by replacing river sand with Taklamakan Desert aeolian sand at different mass ratios. The effects of replacement ratio and curing age on compressive strength and microstructure were investigated using compressive strength tests, SEM, and EDS. A quadratic regression model was established by response surface methodology for aeolian sand concrete, using the replacement ratio, curing age, and Ca/Si ratio as variables. The results showed that compressive strength first increased and then decreased with increasing aeolian sand content, with the 20% replacement group achieving the highest strength, reaching 43.6 MPa at 28 d and 48.33 MPa at 56 d. Strength increased with curing age, but the growth rate slowed after 28 days. The SEM and EDS results indicated that suitable aeolian sand content promoted hydration product formation and matrix densification, whereas excessive replacement increased pores and interfacial defects. The Ca/Si ratio generally increased with curing age. The model showed good fitting accuracy, with R2 = 0.9970, providing a reference for the strength prediction and mix design optimization of aeolian sand concrete.