Research on mechanical and durability properties of sintered sludge cement

Abstract

The urgent need to address climate change has prompted a focus on carbon-intensive industries, such as cement production. This study explores a novel approach by utilizing dredged sludge (DS), a hazardous waste, treated with mechanical-thermal activation to enhance its pozzolanic activity. The resulting sintered sludge ash (SSA) serves as an supplementary cementitious material for the preparation of sintered sludge cement (SSC), potentially reducing the carbon footprint of traditional cement. Compressive strength tests reveal that up to a 30% dosage of SSA maintains minimal change in 28 d strength while improving chloride erosion resistance. However, a 50% SSA dosage leads to reduced strength due to inadequate cement. Freeze-thaw cycle tests indicate a negative impact on frost resistance with increasing SSA dosage. Micro tests, including heat of hydration, mercury intrusion porosimetry (MIP), and scanning electron microscope (SEM), provide insights into the evolving properties of SSC. A lower SSA dosage initially increases porosity, but hydration progress results in a denser microstructure.