Effect of particle size and CO₂ treatment of waste cement powder on properties of cement paste

Abstract

This paper studies the role of CO 2 treatment and the impact of particle size (<75 μm and 75–150 μm) of waste cement powder (WCP) with different cement replacement content (0%, 5%, 10%, 15%, 20%, and 30%) on the physical properties and microstructure of blended cement paste. The results show that carbonation of WCP can effectively increase the flowability of paste due to the formation of calcite and decrease the porosity of WCP microstructure, while the water demand to achieve the same workability decreases with increasing size of WCP particles. Cement paste containing decreased particles of carbonated waste cement powder possesses a higher 28 day compressive strength due to formation of a higher amount of calcite and hydration products, based on the thermogravimetric analysis.