Strength and Microstructure Assessment of Partially Replaced Ordinary Portland Cement and Calcium Sulfoaluminate Cement with Pozzolans and Spent Coffee Grounds

Supplementary cementitious materials are considered a viable and affordable way to reduce CO2 emissions from the cement industry’s perspective since they can partially or nearly entirely replace ordinary Portland (OPC). This study compared impact of adding spent coffee grounds (SCGs), fly ash (FA), volcanic (VA) two types cement: OPC calcium sulfoaluminate (CSA). Cement samples were characterized using compressive strength measurements (up 210 days curing), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), diffraction (XRD), attenuated total reflection infrared spectroscopy, hydration temperature measurements. In all studied systems, presence SCGs reduced delayed process. CSA composite containing 3.5% SCGs, 30% FA, VA showed values 20.4 MPa 20.3 MPa, respectively, meeting minimum requirement for non-structural applications. Additionally, results indicate formation gel, silicate hydrate (C-S-H) in OPC-based cements, alumino-silicate (C-A-S-H) as well ettringite CSA-based cements.