Studies on the Thermal-Physical Treatment of Waste Concrete for Use in Lightweight Aggregate Concrete

Abstract

Demolition of buildings can generate large amounts of waste concrete, which if used effectively, can help reduce both the extraction of raw materials and carbon emissions. However, the presence of old cement mortar affects the effective use of waste concrete as a recycled fine aggregates. This study aims to remove old mortar adhering to the surface of waste concrete coarse aggregates via thermal-physical treatment. This study involves assessing the thermal-physical treatment technology and comparing the performance of recycled fine aggregates prepared using this technology with that of fully recycled fine aggregates. The results of this study illustrate the effect of the thermal-physical treatment technique on the preparation of recycled fine aggregates from waste concrete and the effect of fully recycled fine aggregates and recycled fine aggregates prepared using this technique on ceramsite concrete. The results revealed that the thermal-physical treatment technology has a positive effect in improving the quality of recycled fine aggregates prepared via the thermal-physical treatment technique. This technique helps to significantly improve the compressive strength, ultrasonic velocity, resistance to sulfate attack, and microstructure of the recycled ceramsite concrete compared with the fully recycled fine aggregate.