Thermodynamic, microstructural and chemometric analyses of the reuse of sugarcane ashes in cement manufacturing

Abstract

Thermodynamic, microstructural, chemometrics, and analyses of mechanical properties of cement-based materials are performed with the addition of agro-industrial residues, which are often discarded in landfills. In this sense, two types of waste ashes of sugarcane bagasse were investigated. All investigated materials were characterized by XRF, TGA, XRD, and SEM/EDS analyses. The experiments of XRF data revealed that the ash additions increased the presence of reactive inorganic compounds, such as K2O, in the mixture of concrete ingredients. Subsequently, thermodynamic properties revealed that the complex hydration reactions associated with the processing of the concrete admixture are spontaneous processes (ΔrG ~ −400 kJ.mol−1). Further, XRD and SEM/EDS data showed that the hydrated waste ashes presented elevated quantities of amorphous phases. For all concretes, the presence of the main cementitious amorphous phase CSH was detected. Finally, chemometric analysis of the axial compressive strength and tensile resistances of the cement-based materials revealed that, after 365 days, the ashes could be used as partial cement substitutes that typically emit CO2 when applied to constructions.