Experimental study on thermal and mechanical behavior of mortar-aggregate under microwave irradiation

Abstract Microwave assisted concrete recycling is highlighted by a large number of research groups all over the world due to its potential for significant process benefit. In this paper, systematic experiments are established to investigate the heating outcomes of mortar-aggregate under microwave irradiation. Four different aggregates are selected that widely used as aggregates in concrete. The temperature variations of mortar and aggregate under different heating times and microwave power inputs are obtained. The crack formation, propagation and material damage during the heating process are illustrated. Push-out tests are conducted after microwave heating process to investigate the interface mechanical behavior of aggregate and mortar. The physical properties of recycled aggregate, including apparent density, porosity, water absorption, toughness and adhered mortar percentage after microwave treatment methods are evaluated. The research proves that microwave irradiation could weaken the bonding between mortar and aggregate effectively, which provide a contribution and reference for the further application of microwave-assisted aggregates recycling.