Thermo-mechanical Treatment for Enhancing the Properties of Recycled Concrete Aggregate

This study aims to contribute to the growing area of research on enhancing the quality of recycled concrete aggregate (RCA). Specifically, the combined effect of washing and thermo-mechanical treatment (W-TMT) methods was investigated. The efficiency of the treatment method was evaluated through the removal of adhered mortar (AM), physio-mechanical properties of treated RCA and their microstructure observed by X-ray µCT scan. The results show a significant improvement in the quality of treated RCA with the complementary effect of W-TMT. The highest AM removal and aggregate quality were achieved by the combined W-TMT at a heating temperature of 600°C with significant improvement in water absorption, bulk density and particle density. Moreover, the X-ray µCT results show a lower AM content, less porosity and no damage (even at heating temperature of 600°C) in the treated RCA. It was found that concrete using untreated RCA only achieves the compressive strength of 21 MPa for the 32 MPa concrete mix design whilst concrete made with the treated RCA showed 72% increase in compressive strength and reaches the target strength. The findings highlight the potential of W-TMT method in enhancing the quality of RCA, thereby supporting the progress in concrete sustainability and circularity.