Effect of waste brick powder rich in SiO2 on the physical and mechanical properties of Portland cement concrete containing coarse recycled asphalt pavement aggregates (RAP)

Abstract

Promoting sustainable development involves minimizing the consumption of natural resources, including aggregates, without compromising the performance of concrete. In Algeria, the rapid expansion of road projects results in substantial quantities of Recycled Asphalt Pavement (RAP) generated through milling and excavation of existing bituminous roads. To enhance the reuse of RAP aggregates in concrete, it is well-established that incorporating cement with silica-rich mineral additives can reduce energy consumption and enhance concrete efficiency and performance. This study focuses on investigating the potential use of waste brick powder (WBP) as supplementary cementitious materials (SCMs) to enhance the physical and mechanical properties of concrete containing coarse RAP aggregates. The substitution levels of WBP were set at 0%, 5%, and 15%, respectively, in blends comprising 0%, 25%, 50%, 75%, and 100% RAP aggregates. Various tests were conducted, including slump tests, compression strength analysis, ultrasonic velocity measurements, dynamic elastic modulus assessments, water permeability evaluations, and examination through Scanning Electron Microscope (SEM). The results indicate that blends containing 5% WBP demonstrate improved mechanical and physical properties compared to other blends. However, microstructural and elemental analyses reveal that the enhancement in Interfacial Transition Zone (ITZ) properties is not significant. It was also observed that water absorption decreased with increasing RAP content. Generally, a coarse RAP content of up to 50% proves to be suitable for achieving satisfactory performance in concrete.