Effect of temperature and sulfate erosion on mechanical properties and shrinkage characteristics of cement-stabilized macadam

Cement-stabilized macadam (CSM) is susceptible to deterioration and shrinkage cracking under fluctuating temperatures and salt erosion conditions. This study investigates the effects of ambient temperature, cement dosage, and sulfate content on the mechanical properties and shrinkage behavior of CSM. Compressive strength, splitting strength, dry and temperature shrinkage, hydration products, and microstructure of CSM were analyzed under varying conditions using mechanical tests, shrinkage tests, XRD, and SEM. Results indicated that increasing sulfate content led to more erosion products and the formation of internal cracks, which reduced mechanical performance. Higher curing temperature and cement dosage accelerated hydration, improved aggregate bonding and compaction, and enhanced mechanical properties. For sulfate-free CSM, dry shrinkage strain (DSS) mainly occurs during early dehydration, while temperature shrinkage strain (TSS) increases almost linearly as temperature decreases. In sulfate-containing CSM, DSS exhibits an initial increase followed by a decrease, whereas TSS first decreases and then increases with decreasing temperature. Based on these findings, DSS and TSS models incorporating cement dosage and sulfate content were developed to quantitatively characterize CSM shrinkage under various conditions. The shrinkage process of CSM under cooling and salt erosion can be divided into three stages, primarily reflecting the interaction between shrinkage stress and salt crystallization stress.