Effect of Demolition Concrete Aggregate on the Mechanical Properties of Concrete

Abstract

Currently, the entire world is working together to achieve the Sustainable Development Goals (SDGs) by 2030, and Demolition Coarse Aggregates (DCA) are a key component of this goal. The removal of coarse aggregates from remaining concrete is a major waste management problem and impacts the environment. Our research focus calls for promoting its reuse using the 5R strategy (Refuse, Reduce, Reuse, Recycle, and Rethink). In this study, 20 flexural beams and 60 cylindrical specimens were tested. The water-cement ratio in the concrete mix design was 0.54, and the proportions were 1:2.24:2.57 (M30 grade). The coarse aggregate was partially replaced with demolition coarse aggregates at percentages of 0%, 25%, and 75%. For the purposes of testing, all samples were cured for 14 and 28 days, ensuring reliable outcomes. For the purposes of this study, the unit weight, flexural tensile strength, split tensile strength, and compressive strength were determined. We additionally inquired into using a water-reducing admixture to improve the concrete's tensile and compressive strength as reformed with demolition coarse particles. As to our study results, adding admixture to normal concrete improved its compressive strength, split tensile strength, and flexural tensile strength. In addition, the addition of appropriate admixtures significantly improved the tested strength properties of concrete, while the use of demolition coarse aggregates decreased all of them for all percentages of aggregate replacement. Therefore, adding demolition coarse aggregates to concrete mixes as an admixture could offer a practical solution to manage waste sustainably and improve material performance.