Ternary alkali aluminosilicate cement based on rice husk ash, slag and coal fly ash

Abstract A sustainable hydraulic cement relying primarily on the alkali aluminosilicate chemistry was developed using primarily industrial byproducts as raw materials. The byproduct raw materials included rice husk ash as the main source of amorphous silica, and coal fly ash and slag as sources of aluminosilicates and calcium. In addition, sodium hydroxide and sodium silicate were used as sources of alkalis and soluble silica, and tartaric acid as a set retarder. All these raw materials were used in dry form and were processed into a hydraulic cement via the mechanical effects rendered by ball-milling. The chemical and mineralogical compositions of the hydraulic cement and its hydrates were evaluated. The heat of hydration, strength development characteristics and set time of the cement were also assessed against the ASTM C1157 requirements, and compared with the corresponding properties of Type I Portland cement. The hydraulic cement formulated with rice husk ash met the ASTM C1157 requirements relevant to strength and set time for ‘Genera Use’ (GU) cement, and produced compressive strengths that were higher those obtained with Type I Portland cement.