Thermomechanical beneficiation of recycled concrete aggregates (RCA)

Abstract

In order to move towards a circular economy, it is relevant to maximize the usage of waste materials in construction activities. One such resource that could be extracted from abundant waste are Recycled Concrete Aggregates (RCA). Many methods have been proposed in the last few decades to improve the quality of RCA, with limitations in terms of energy demand or low yield. In the present study, an attempt has been made to employ thermo-mechanical beneficiation to obtain high-quality coarse and fine aggregates, with high yield (>90%). Heating temperature, feed size and residing duration are variables that have been optimized. When waste concrete chunks are heated for about 60 min at 500 °C (932°F) and milled with steel ball charge, the resulting RCA fractions conform to the limits set by stringent codes and guidelines. The beneficiated coarse RCA thus obtained could give concrete performance comparable to that of pristine granite aggregate concrete.