Effect of early strength anti-cracking materials on drying shrinkage of recycled cement stabilized macadam
Ge Mou, Aiqin Shen, Zhenghua Lyu, Lusheng Wang, Yinchuan Guo, Ziyu Wei, Lei Yin
Abstract
The increasing road maintenance projects lead to a large amount of construction waste and long-term closed traffic, enabling a rigid demand for early strength recycled cement-stabilized macadam (ERCSM), which can achieve rapid cold recycling. Given that ERCSM is prone to early drying shrinkage cracking, this study aimed to reduce the occurrence of early drying shrinkage cracking by adding early strength anti-cracking materials (EAMs). Therefore, a drying shrinkage test of cement mortar was carried out to determine the types, contents of anti-cracking materials, and their mixing proportions with early strength composite materials. The effect of EAM on the drying shrinkage of ERCSM was also studied. The results show that the anti-cracking material E1 has better crack resistance. Two types of EAMs (M1 and M2) composed of E1 and different early strength composite materials, were determined. EAM could reduce the drying shrinkage of the recycled cement-stabilized macadam base, and M2 had a better resistance to early shrinkage. After adding M2, the total drying shrinkage coefficient at 2 and 3 d decreased by 91.7% and 74.7% compared with the control group, respectively. Microscopic test show M2 can accelerate the hydration process of cement and promote the formation of expansion products at early ages.