Development and fracture characterization of enhanced ductile engineered geopolymer composites utilizing construction and demolition waste-based recycled binders and aggregates

The potential of construction and demolition waste (CDW) in developing ductile engineered geopolymer composites (EGCs) has not yet been fully explored, particularly when integrated as both recycled precursors and aggregates. This study investigates the fracture characteristics and mechanical performance of CDW-based EGCs, prepared with a ternary CDW-binder system comprising recycled brick, ceramic tile, and concrete waste powders, along with CDW aggregates, including recycled concrete aggregates (RCA), recycled ceramic tile aggregates (RTA) and recycled brick aggregates (RBA). Furthermore, the effect of adding supplementary cementitious materials, such as slag (GGBS), metakaolin (MK), and fly ash (FA-C), on the compressive, flexure, tensile, ductility and fracture characteristics of EGCs were considered. Results demonstrated that EGCs incorporating up to 70 % CDW precursors and 100 % CDW aggregates can achieve compressive, flexural, and tensile strengths exceeding 71 MPa, 11 MPa, and 5.7 MPa, respectively, while exhibiting a pronounced strain-hardening response and multiple microcracking behavior. Among the CDW aggregates, RCA delivered the highest mechanical performance & rsh;and ductility compared to RTA and RBA, closely matching control mixtures with silica sand. These attributes establish CDW-EGCs as a sustainable alternative to conventional cementitious materials, offering a structurally viable construction solution without compromising performance.