Preparation and properties of green high ductility geopolymer composites incorporating recycled fine brick aggregate

Abstract

Reusing of waste bricks, particularly as recycled aggregates to prepare concrete, plays an important role in reducing dependence on natural resources and solving the problem of waste accumulation. However, there is a lack of applied research on fine-grained size brick aggregates. In this study, recycled fine brick aggregate (RFBA) and industrial by-products are successfully used to develop green high ductility geopolymer composites (RFBA-HDGC) with appropriate composition tailoring. The effects of the volume fraction of river sand replaced by RFBA, slag content, and silicate modulus as the most important matrix parameters on the compressive strength, fracture properties, tensile properties, fiber/matrix interface and crack characteristics of the composite are evaluated. The experimental results show that increasing slag content and decreasing the silicate modulus can improve the fracture strength, compressive strength, and tensile strength. The utilization of recycled fine brick aggregates reduces the strength, but the close binding of high-roughness RFBA to the matrix promotes the interlocking effect between the fiber and the matrix, which increases the frictional bond during the fiber pull-out process and facilitates the development of fiber bridging capabilities. The maximum tensile strength and tensile ductility of the high ductility geopolymer composites prepared from the RFBA with 100% volume fraction can reach 4.41 MPa and 4.27%, respectively, with medium strength and medium-to-high ductility grades. This research shows the engineering application potential of RFBA-HDGC and can provide new solutions for the utilization of brick aggregates.