Systematic Review on Alkali-Activated Binders Blended with Rice Husk Ash

Production of alkali-activated binders is a developing research field that utilizes industrial/agricultural by-products and solid waste for the development of sustainable concrete. This paper comprehensively reviews the literature relating to rice husk ash (RHA)-based alkali-activated binders incorporating fly ash (low/high calcium) and blast furnace slag. The literature demonstrates that the properties of raw material significantly influence the formation of the alkali-activated gel matrix. Every precursor (low/high calcium fly ash and slag) that is used to develop alkali-activated binders with RHA have their own reaction mechanism dependant on their specific chemical composition. Hence the incorporation of RHA influences each binder in a unique way depending upon the alkali activation process and reaction mechanisms. The incorporation of RHA, in the range 5%-15%, with blended slag alkali activated binders, yields better compressive strength, when compared with RHA blended with fly ash (low/high calcium). The review presented in this paper is very useful to understand the behavior of alkali-activated binders incorporating RHA and in advancing the research into the successful application of RHA as a binder for alkali-activated materials.