Sustainable utilization of ultrafine rice husk ash in alkali activated concrete: Characterization and performance evaluation

This paper investigates the novel effect of ultrafine rice husk ash (URHA) on the properties of alkali-activated concrete. Rice husk ash was obtained as waste from biomass energy production and further processed to obtain URHA. The URHA was first characterized using various techniques to understand its morphology, structure and chemical composition. The URHA was then used to replace fly ash in alkali-activated fly ash/slag concrete up to 10%, and the effects on the performance were evaluated. The optimum dosage of URHA was assessed based on the compressive strength and the resistance to chemical attacks was carried out on the control mixture and that incorporating the optimum URHA. Microstructural properties of some of the control mixture and that incorporating the optimum URHA content was also investigated. Results from this study showed that the use of URHA as a 5% replacement of the FA is optimum that ensured high performance.