The Role of Biomass in the Synthesis of Geopolymers: A Review

Abstract

The need to attain a sustainable economy has encouraged researchers to develop alternate routes to the production of geopolymers. Considering the high emissions of CO₂ in the production of ordinary Portland cement (OPC), geopolymers which are conventionally produced by mixing an aluminosilicate source with activators, are projected as their possible substitutes due to their lower emissions. There is, however, a need to further reduce the effect of their synthesis on other environmental indices and also lower production costs. Several sources of biomass such as rice husk, sugar cane bagasse, olive pine bottom ash, maize husk, maize cob and many others, due to their renewable form and high silica content, have been investigated for this purpose. Calcium-rich ashes such as wood ash have also been used. The results obtained vary widely but also suggest that there are feasible replacements for the synthetic silicate solution. This review projects results obtained from various researchers and various sources of biomass and compares their methods of introducing biomass in geopolymer binders.