Performance evaluation and cost analysis of ternary blended geopolymers for sustainable built environment under different curing regimes

Geopolymer technology provides ecological and monetary benefits in supporting waste management. This study examines the influence of different aluminosilicate materials (85-100 % ground granulated blast furnace slag (GGBS), 0-15 % fly ash (FA), and 0-15 % waste glass powder (WGP)) and curing regimes (water and steam curing) on the mechanical and durability properties and production cost of geopolymers. The water-binder ratio, binder-fine aggregate, and alkaline activator-binder ratios were kept constant, whereas different amounts of superplasticizer were used in all the samples to achieve the target strength of 250 mm. The results revealed that the compressive and flexural strengths of specimens containing FA and WGP outperformed those of GGBS-based geopolymers. The compressive and flexural strength results demonstrated that the optimal FA and WGP replacement levels in ternary blended geopolymers were 10 % and 0-15 %, respectively; subsequent increases or decreases in FA and WGP replacement levels in most of the specimens resulted in mechanical properties similar to those of GGBS-based geopolymers without a significant increase in the production cost. Moreover, exposing specimens to freeze-thaw cycles led to higher compressive strength, ultrasonic velocity values, and weight irrespective of the curing regime, which can be credited to the continued geopolymerization reaction. Contrary to freeze-thaw cycles, only some specimens exhibited higher compressive and flexural strength once exposed to magnesium sulfate (MgSO4) solution. Like compressive and flexural strengths, the resistance of ternary blended geopolymers against freeze-thaw and sulfate attack is higher than that of GGBS-based geopolymers. It is also revealed that water-and steam-cured specimens provide better early-and later-age mechanical and durability properties; therefore, the choice of curing regime should be based on potential application. The positive results of this study indicate that ternary blended geopolymers have the potential to solve environmental challenges while also being futuristic and cost-effective in the production of eco-friendly and structural-grade materials.