Preparation and properties of geopolymer recycled concrete: A review of recent developments

Abstract

Geopolymer recycled aggregate concrete (GRAC) is an eco-friendly building material. The raw materials for preparing GRAC typically include industrial solid waste rich in silica-alumina elements as a substitute for cement, along with recycled aggregates (RA) derived from processed waste concrete or construction debris. These materials undergo geopolymerization through activation with alkaline or acid solutions. The development of GRAC can effectively address environmental issues. However, the incorporation of RA leads to the formation of multiple interfacial structures within the concrete matrix, along with micro-cracks generated during the crushing process of RA, significantly impacting the practical use of GRAC. This review systematically evaluating the fresh properties, mechanical properties (including compressive strength, tensile strength, flexural strength, and elastic modulus), and durability (involving resistance to chloride ion penetration, acid and sulfate attack, high temperature and freeze–thaw cycle) of GRAC. Furthermore, a comparative evaluation method based on the carbon emissions of concrete per unit strength is suggested to assess the carbon emissions performance of GRAC against traditional cement concrete. Building upon existing literature, future research directions for GRAC are suggested, providing theoretical guidance for the utilization of RA in geopolymers and facilitating the practical application of GRAC in the sustainable green building industry.