Effect of Rice Hull Ash on the Geopolymerization of a Kaolinite Clay from Togo

Geopolymers have recently emerged as a promising class of inorganic aluminosilicate polymer materials. They present a viable alternative to Portland cement, which is well known for its significant contribution to greenhouse gas emissions. To support the reduction of these emissions, this study aims to develop geopolymer cements by investigating the impact of rice husk ash on the geopolymerization of local kaolinite clay using an alkaline solution. Rice husk ash (with a SiO<sub>2</sub> content of 91.6%), obtained by calcining rice husks at 600°C, serves as a source of amorphous silica. The GP<sub>0</sub> geopolymer material, derived from clay calcined at 750°C and activated with a 12N sodium hydroxide solution, exhibits a compressive strength of 9.9 MPa. This mechanical strength was enhanced by incorporating rice husk ash, which produces sodium silicate solutions as activators. The addition of 10% rice husk ash increased the compressive strength from 9.9 MPa to 15.9 MPa. The sodium silicate solution derived from the ash proved to be an effective alkaline activator in the geopolymer synthesis. Consequently, rice husk ash can potentially replace commercial sodium silicate solutions, contributing to the formulation of more eco-friendly materials. However, further research is needed to optimize the mechanical properties of these geopolymers.