Performance evaluation of green‑concrete pavement material containing selected C&D waste and FA in cold regions

摘要

To evaluate the performance of green-concrete road material in cold regions of northern China, concrete was prepared with 0%, 50%, and 100% air-entrained coarse recycled concrete aggregate (CRCA) to replace coarse natural aggregate (CNA). Low-volume and high-volume fly ash (FA; LFA- and HFA-) were also used to replace some cement. The mass loss, residual compressive strength, relative dynamic modulus of elasticity (RDME), and concrete microstructure were measured after being subjected to certain freeze-thaw (F-T) cycles. Results indicated that an appropriate amount of CRCA can help optimize the pore distribution of concrete, and improved the frost resistance of concrete. FA can improve the workability of concrete and enhance the bonding performance of aggregate-mortar interfacial transition zone. Additionally, the LFA-based concrete showed excellent improvement in the resistance to F-T environment. However, the HFA had an adverse effect on strength of pore structure and weakened frost resistance of concrete. When the CRCA replacement was 50% and the FA content was 20%, the RDME and residual compressive strength of the concrete showed the least reduction after F-T test.