Synthesis and characterization of geopolymer binders based on local materials from Burkina Faso – Metakaolin and rice husk ash

Abstract

Geopolymer binders constitute an environmental friendly alternative of Portland cement, wellknown for its contribution to the emission of greenhouse gases. In this article, we study the possibility of valorizing local materials in Burkina Faso, namely metakaolin and rice husk ash, in geopolymer binders synthesis using sodium hydroxide solution.The study focused on the influence of the addition of rice husk ash and the curing temperature on the mineralogical, microstructural, physical and mechanical properties of geopolymer binders, through X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, weight loss, apparent density, porosity accessible to water and compressive strength. Three types of geopolymer binders were synthesized in this study: geopolymer binders based on metakaolin alone (AN) and two other binders containing 5% (BN) and 10% (CN) of rice husk ash respectively.The results obtained show the formation of new mineral phases and an improvement of the mechanical strength with the addition of rice husk ash and with curing temperature. There is also a high porosity for all synthesized geopolymer binders. These results are presented and discussed in terms of SiO2/Al2O3 ratio and degree of polymerization.