Rapid regeneration cement-stabilized macadam: Preparation, mechanical properties, and dry shrinkage performance

Based on the mechanical strength and dry shrinkage of cement mortar, the early strength anti-cracking materials ZFP (mixture of single early strength agents Z1 and Z3 and expansion agent P) and ZSP (mixture of single early strength agents Z1, Z2, and Z3 and expansion agent P) are optimized. Using waste cement-stabilized macadam in road base maintenance as an aggregate, rapid regeneration cement-stabilized macadam containing early strength anti-cracking materials with different contents was prepared, and the mechanical properties and dry shrinkage performances were tested. The early strength anti-cracking mechanism of rapidly regenerated cement-stabilized macadam with different ZSP contents was explored via microscopic experiments. The results show that ZFP and ZSP have an optimal mixing ratio, which makes the setting time, mechanical properties, and dry shrinkage of cement mortar the best. The 2 d compressive strength of rapidly regenerated cement-stabilized macadam containing 8% ZSP was 6.23 MPa, while the 3 d compressive strength of the rapid regeneration cement-stabilized macadam containing 7% ZFP was 6.14 MPa, and the corresponding dry shrinkage coefficients were 91.6% and 11.2% lower than those of the control group, respectively. The chlorine salt, sulfate, and organic amine in ZSP react with calcium hydroxide, which accelerates the hydration process of cement and improves the early strength of rapidly regenerated cement-stabilized macadam. Hydration products, such as expansive sulfuraluminate and chloroaluminate produced by cement hydration in rapidly regenerated cement-stabilized macadam and calcium oxide in ZSP, inhibit early dry shrinkage cracking.