Experimental Study of the Heating Potential of Mortar-Aggregate under Microwave Irradiation

Abstract

Microwave heating is a novel and promising method to remove mortar that adheres to aggregates in recycled concrete. A systematic experiment was carried out to evaluate the heating results of mortar-aggregate composite materials after microwave heating with different power and irradiation times. It was revealed that the surface temperature and heating rates of the mortar and aggregate linearly increased with the irradiation time and powers level. After microwave treatment, macrocracks generated along the mortar–aggregate interface and penetrated the mortar matrix until the mortar broke. Moreover, based on the push-out tests, it was found that the interface bond strength of mortar-aggregate after microwave treatment was much lower than that of the untreated specimens. The influence of the temperature difference on the residual bond strength is also discussed in this study. The parametric study confirmed that the bonding strength between mortar and aggregate after microwave heating is reduced. This experimental investigation could provide a basis and reference for microwave-assisted concrete recycling for industrial applications.