Synergistic activation of ground granulated blast furnace slag using ternary industrial solid wastes for the preparation of eco-friendly geopolymers: Optimization of curing methods

Abstract

The development of eco-friendly geopolymers without commercial alkali activators has attracted considerable attention due to their superior economic and environmental advantages over conventional geopolymers. This study proposes a novel approach for synthesizing sustainable geopolymers using four industrial solid waste: red mud, phosphogypsum, ground granulated blast furnace slag, and calcium carbide slag. The effects of phosphogypsum and calcium carbide slag content, along with different curing methods, on flexural strength, compressive strength, and fluidity were systematically investigated. Four micro-characterization techniques were employed to elucidate hydration mechanisms under varying formulations and curing methods. The results indicate that appropriate incorporation of phosphogypsum under water curing significantly improves compressive strength and fluidity. However, excessive phosphogypsum addition causes expansion, cracking, and substantial strength loss. Among the curing methods evaluated, sealed curing proved more effective than heat curing, achieving high strength while offering greater practical convenience. The developed geopolymer exhibits potential for use in low-strength unreinforced applications, contributing to the sustainable advancement of green construction materials.