Circular Economy Processes for CO2 Capture and Utilization Chapter 7

The construction sector is one of the main contributors to CO2 emissions, with around 10 Gt of CO2 emitted in 2021. Moreover, it is also a large contributor to waste streams, amounting to 37.1% of the total European wastes in 2020. To reduce the sector’s environmental impact, this chapter addresses CO2 capture by mineral carbonation using construction and demolition waste (C&DW). This process leads to a double contribution to circular economy by combining two waste streams (CO2 and C&DW), resulting into valuable materials such recycled concrete aggregates (RCA) with improved properties and other fillers that can be re-used in the construction sector. Along this chapter, the main mineral raw materials used in the construction sector are described and the process of mineral carbonation is explained, with a focus on C&DW. The phenomena involved in this process are described and the influences of operating parameters such as water-to-cement ratio, relative humidity, pH, temperature, and CO2 concentration are reviewed.