Characterization and properties of elephant grass ashes as supplementary cementing material in pozzolan/Ca(OH)2 pastes

This work presents the behavior of two elephant grass ashes, as pozzolans, elephant grass cameroon (EGC) and napier (EGN), calcined under controlled conditions (700 °C). The ashes were initially submitted to a chemical treatment with HCl in order to reduce the potassium content. Both ashes showed high pozzolanic activity after 7 days of curing, with at least 85% of fixed lime. The thermogravimetric and micro-Raman analysis in elephant grass ashes/Ca(OH)2 pastes confirmed that the main hydrated phases during the pozzolanic reaction consisted of CSH gels, by the weight loss between 60 and 300 °C in TG analysis and the band at 680 cm−1 in Raman spectrums. Based on the achieved results, it is possible to conclude that elephant grass ashes can be used as supplementary cementing materials.