Development and performance of solid alkali-activated concrete incorporating calcium sulfate whisker: a sustainable construction solution

The environmental impact of conventional concrete, particularly the high CO2 emissions associated with ordinary Portland cement (OPC), has encouraged the development of sustainable alternatives. This study investigates solid alkali-activated concrete (SAAC) incorporating calcium sulphate whisker (CSW), with ground granulated blast furnace slag (GGBFS) as the primary binder and anhydrous sodium metasilicate (ASM) as the solid activator. The influence of CSW on the mechanical, durability, thermal, and microstructural properties of SAAC was evaluated. CSW incorporation enhanced compressive strength by up to 10.81%, splitting tensile strength by 41.94%, and flexural strength by 51.85%. Water absorption and sorptivity results indicated reduced permeability, while elevated-temperature testing demonstrated considerable residual strength up to 600 °C. Microstructural analyses further supported the development of a dense matrix and improved internal structure with CSW incorporation. Response surface methodology (RSM) identified an optimum mix comprising 528.21 kg/m³ binder, 3.10% CSW, and 19.78% activator, with a desirability index of 0.859. The findings demonstrate the potential of CSW modified SAAC as a sustainable construction material with enhanced mechanical and durability performance.