The investigation of concrete damage and recycled aggregate properties under microwave and conventional heating

Microwave-assisted concrete coarse aggregate recycling technology is considered as a potential concrete recycling technology, which is of great significance to environmental protection and sustainable development of the construction industry. In order to study the damage evolution process of concrete and the properties of recycled coarse aggregate (RCA) under microwave and conventional irradiation, the heating effect of concrete under different heating paths was studied. The heating efficiency, crack propagation law, failure mode and energy consumption of concrete under different heating conditions were obtained. The uniaxial compressive strength (UCS) test was carried out after heat treatment to explore the concrete strength weakening law. The apparent density, water absorption, point load strength and surface micro-crack characterization of RCA after heat treatment were comprehensively analyzed. The results show that microwave heating technology has greater advantages than conventional heating methods that can effectively promote the development of interfacial cracks between mortar and aggregate, weaken the strength of concrete and liberate high-quality RCA under certain conditions. The research results can provide reference and contribution for microwave-assisted concrete crushing and aggregate recovery process.