14 - High-volume recycled concrete fines blended cements

Abstract

The management of construction and demolition waste, particularly waste concrete, poses significant environmental challenges that necessitate the development of effective recycling methods. Recycled concrete fines (RCF), typically obtained from the recycling process of waste concrete, have demonstrated potential as a novel supplementary cementitious material when appropriately treated for use in cement. RCF can be employed as a partial replacement for cementitious materials, leveraging its high calcium, silicon, and aluminum content, thereby reducing cement consumption and CO2 emissions. However, excessive RCF usage can adversely affect the compressive strength and workability of mortar, with most studies recommending a substitution rate not exceeding 30%. To enhance RCF reactivity and broaden its applications, various modification techniques have been explored, including mechanical activation, heat treatment, and carbonation modification. These methods aim to improve the physical and chemical properties of RCF, thereby enhancing its performance in mortar and concrete. This chapter provides a thorough assessment of RCF's feasibility and benefits in cement applications, summarizing current research and promoting technological advancements to reduce carbon emissions in the cement industry. Future research should focus on optimizing energy consumption, wastewater treatment, durability, and activation efficiency to fully exploit RCF's potential in cementitious materials.