The influence of recycled aggregate on the properties of geopolymeric recycled concrete: A comprehensive review

Abstract

This paper offers a comprehensive review of geopolymeric recycled concrete (GRC) research, particularly focusing on mechanical properties, durability, microstructure, and the interfacial transition zone (ITZ). The study emphasizes the influence of recycled aggregate (RA) content on GRC performance. Findings indicate that higher RA content leads to a gradual reduction in GRC’s compressive, tensile, and flexural strengths, elastic modulus, and toughness. The elastic modulus is most affected, followed by compressive strength, while tensile strength experiences the least decline. Moreover, increased RA content is associated with elevated water absorption, decreased resistance to chloride ion permeability, sulfate corrosion, acid, frost, and carbonization in geopolymer concrete. The integration of RA creates more intricate ITZs in geopolymer concrete, resulting in reduced bonding strength and a looser, more porous microstructure. However, the use of geopolymers can mitigate these effects by enhancing bonding in ITZs. The paper also presents a statistical analysis of compressive strength test results from various studies and proposes a preliminary method for estimating the compressive strength of geopolymer concrete with different RA replacement rates.