Production of a highly pozzolanic sugarcane bagasse ash via densimetric fractionation and ultrafine grinding

Abstract

Sugarcane bagasse ash is a by-product produced by the energy cogeneration from biomass burning. Different processes can be applied to this material to adapt its chemical and physical characteristics to its use as pozzolan. This work aims to evaluate the effectiveness of the densimetric fractionation process in production of sugarcane bagasse ash with high pozzolanicity. Initially, a quartz-rich ash was collected in an industrial boiler and subjected to densimetric fractionation to remove the quartz particles through decantation. Then, the potentially pozzolanic ash portion was subjected to ultrafine grinding. The results showed high amorphous content (94.8%) in the ash after fractionation. Electrical conductivity and performance index tests confirmed the adequate pozzolanicity of the processed ashes. In addition, cement-based pastes with 20% cement replacement by bagasse ash (in mass) showed a reduction in the heat of hydration. Thus, the densimetric fractionation was efficient in producing a material with high reactivity compared to the original ash due to the reduction of contaminants and, consequently, the increase in the amorphous silica concentration.