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

Abstract

Cement is an essential construction ingredient and its demand has increased multifold during the last couple of years due to various construction activities. For the manufacture of cement, limestone is the key component that is the major source of carbon dioxide (CO2) emission. Moreover, local municipalities all over the world have long been concerned about the disposal of sewage sludge. Larger quantity of sewage sludge generation is becoming an urgent alternative solution for sludge disposal and waste recycling in construction materials. In accordance with the concept of sustainability, low carbon 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 cement containing different percentages of SSA with 10% CLS is compared with composite cement containing fly ash (FA) in different percentages addition with 10% CLS. The outcome from the study shows that the utilization of SSA with CLS up to 45% would be possible with OPC as it indicates an acceptable level of compressive strength, conservation of depleting limestone reserves, saving in thermal and electrical energy besides emissions reduction of CO2.