Feasibility study of using wash water on workability, mechanical properties and durability of alkali-activated concrete

Abstract The construction industry continually seeks sustainable practices to reduce environmental impact and promote resource efficiency. The environmental impact of wash water generated during ready-mix concrete production has emerged as a major concern for sustainable construction practices. The objective of this experimental study was to evaluate the feasibility of employing wash water in alkali-activated concrete (AAC). AAC is one of the major research outcomes in the field of sustainable construction materials. Binary binder systems comprising Class F fly ash (FA) and ground granulated blast furnace slag (GGBS) were activated using solid activators at 8%, 12%, and 16% content by binder mass. A comprehensive experimental program was conducted to evaluate the influence of wash water compared to tap water on the workability, density, mechanical properties, and acid resistance of AAC. Results demonstrated that WW significantly improved workability, with slump values increasing by 56–63% and enhanced compressive strength by 4.4–28% across all activator dosages and curing ages. While both TW and WW mixes exhibited significant strength degradation under acid exposure, wash water specimens demonstrated a slightly lower strength loss, indicating no adverse effect on acid resistance. These findings suggest that wash water can be effectively repurposed as mixing water in AAC; however, further investigation into long-term durability and microstructural characteristics is recommended before its large-scale application.