Performance evaluation of coffee husk ash based one-part self compacting alkali activated slag concrete mixes

Abstract Alkali-activated binders are low-carbon alternatives to cement, produced by reacting an alkali activator with an alumino-silicate precursor. However, common alkaline activators like NaOH and Na 2 SiO 3 are highly corrosive, limiting their practical use. This study developed one-part alkali-activated binders from agricultural and industrial waste to address challenges posed by conventional two-part systems. Further performance evaluation of alkali activated slag mixes were evaluated using the developed solid activator. The approach supports sustainable waste management, offers an eco-friendly alternative to Portland cement, and lowers carbon emissions. Using solid alkali-activator sodium metasilicate and precursors like coffee husk ash (CHA), Ground granulated blast furnace slag, and ferrochrome slag, one-part alkali-activated self-compacting concrete (OPASC) mixes were created through Taguchi design experiments. The experimental trials of OPASC were evaluated for fresh, mechanical, microstructural, and durability properties. Results showed flowability between 700 and 765 mm, compressive strength of 50–63 MPa, flexural strength of 3.05–3.58 MPa, splitting tensile strength of 2.7–3.58 MPa, and elastic moduli of 30–32 GPa. These properties were comparable to the reference ordinary Portland cement self-compacting concrete mix, which had a compressive strength of 55 MPa, flexural strength of 4 MPa, splitting tensile strength of 2.8 MPa, and elastic modulus of 30 GPa at 28 days. The OPASC mix showed lower water absorption, high concrete quality (UPV > 4.5), and better performance at elevated temperatures. The study suggests that CHA-based alkali-activated materials can be effectively used, reducing waste and offering viable structural properties.