Effect of moisture on concrete damage and aggregate recycling under microwave irradiation

Microwave-assisted concrete aggregate recycling is a novel green technology, which causes less pollution and generates low energy during heating. This study aimed to explore the influence of moisture content on the heating process of concrete as well as its strength under microwave irradiation. Interfacial debonding of aggregate and mortar after the microwave irradiation was analyzed. Through a uniaxial compression experiment, the compressive strength of test blocks with different moisture contents is gained after microwave irradiation. The changes of microstructure are obtained using Scanning Electron Microscopy analysis. The results demonstrated that microwave power and moisture content were two important factors affected the concrete breaking. When the moisture content of the test block is relatively high, the concrete will break with a short irradiation time and low temperature under a high microwave power input. The aggregate–mortar interface separation was evident, and intact aggregates with low mortar adhesion could be picked out from the crushed concrete. In this study, we provided a reference for further development of microwave-assisted concrete recycling technology.