Sustainable use of sugarcane bagasse ash in cement-based materials

Bagasse is biomass residue generated on extraction of juice from sugarcane. It is commonly used as fuel for electricity generators, and its calcination produces sugarcane bagasse ash (SCBA). Finely ground SCBA can be used as partial replacement for cement. In this study, the effects of SCBA incorporating different quartz contents on properties of cement pastes and mortars were investigated. SCBA with a high carbon content retrieved from Brazilian industrial boilers was washed with water. Two ashes, namely top wash SCBA with a low quartz content and bottom wash SCBA with a high quartz content, were obtained. Both ashes were compared with the as-received control ash. The SCBA samples were recalcinated by conjugate burning and then finely ground. Results show that bottom SCBA had more crystalline phases, while top SCBA was more active, achieving a higher pozzolanic activity. Isothermal calorimetry showed that SCBA cement released increased heat of hydration due to heterogeneous nucleation and exothermic hydration reactions. Mercury intrusion porosimetry showed that SCBA contributed to refining the pore structure. Mechanical strength results indicated that SCBA can be used for partial replacement of cement, enhancing the sustainability and engineering properties of cement-based materials.