Enhancing the Strength of Recycled Concrete Using Thermal-Mechanical Treated Recycled Concrete Aggregate

The rising demand for natural aggregates in the construction industry poses significant environmental concerns, prompting the need for sustainable alternatives. This study in-vestigates the use of recycled concrete aggregate (RCA) derived from laboratory waste and the effectiveness of thermal-mechanical treatment (TMT) in improving its quality. The TMT process involved heating RCA to 250 °C followed by 500 revolutions of mechanical grinding to reduce adhered mortar. Treated RCA (TRCA) was used to replace natural coarse aggregate (NCA) in concrete mixtures at substitution levels of 25–100%. Tests were conducted on both aggregate and concrete properties, including specific gravity, water absorption, abrasion resistance, crushing value, compressive strength, elastic modulus, and interfacial transition zone (ITZ) analysis using scanning electron microscopy (SEM). TMT reduced RCA’s water absorption from 5.24% to 4.79% and increased specific gravity from 2.45 to 2.53. Concrete with 50% TRCA achieved 19.2 MPa compressive strength and 22.199 MPa elastic modulus, comparable to the reference concrete. SEM images revealed a denser and more homogeneous ITZ. These findings suggest that TRCA processed through TMT from laboratory waste is a promising, eco-friendly alternative material—particularly effective at replacement levels up to 50%.