Production of low carbon dioxide cement containing sewage sludge ash as mineral admixture

Abstract

Cement is an essential construction ingredient, and the demand for it has increased multifold during the last couple of years due to various construction activities. For the manufacturing of cement, limestone is a key component, which is a major source of carbon dioxide (CO2) emission. Moreover, municipalities all over the world have long been concerned about the disposal of sewage sludge. Due to increased generation of sewage sludge, urgent alternative solutions are required for sludge disposal, one of which is recycling of waste into construction materials. In accordance with the concept of sustainability, low carbon dioxide cement is produced in the current study by blending sewage sludge ash (SSA) and carbide lime sludge (CLS) (industrial waste) with ordinary Portland cement (OPC). In terms of physical properties, the influence of low carbon dioxide cement containing different percentages of SSA with 10% CLS is compared with that of composite cement containing fly ash at different percentages with 10% CLS. The outcome from the study shows that the utilization of OPC blended with up to 45% SSA with CLS would be possible, as it results in an acceptable level of compressive strength, conservation of depleting limestone reserves, savings in thermal and electrical energy and reduction of carbon dioxide emissions.