Use of asbestos cement tile waste (ACW) as mineralizer in the production of Portland cement with low CO2 emission and lower energy consumption

Abstract

The reuse of solid waste by the cement industry promises a reduction in the amount of raw materials used for the production of clinker (clay and limestone), which may result in lower energy consumption and CO2 emissions. In this context, asbestos-cement tile waste (ACW) represents an alternative to the inputs used in the clinker process because of its similar chemical composition to that of limestone. However, there is a dearth of studies that address the effect of sulfur dioxide (SO3), present in the ACW as mineralizing agent during the clinker process. Thus, this study proposes to evaluate the incorporation of ACW in Portland cement production, with the aim of reducing CO2 emissions and energy consumption. Clinkers were produced without ACW (the reference clinker) and by incorporating different proportions of ACW to replace the mixture of limestone and clay (approximately 24%, 49%, 74%, and 86%) at different temperatures (1300 °C, 1350 °C, 1400 °C, and 1450 °C). The phases formed in the produced clinkers were identified using X-ray diffraction (XRD), followed by an analysis of their physical-mechanical properties. From the results obtained, it was observed that the clinkers produced at 1350 °C and containing 74% ACW represent the ideal proportion for the production of experimental cement, exhibiting compressive strength similar to that of pastes produced with reference cement (without adding ACW), in addition to reducing CO2 emissions by 11.85% and energy consumption by 10.13%.