Two-Step Carbonation of Pervious Concrete Prepared with Recycled Concrete Aggregates: Aggregate Property, Experimental Setup and Preliminary Results

To reduce the carbon footprint of cement and concrete industry, CO2 curing has been recognized as one of the sufficient ways. However, the amount of CO2 uptake by the normal structural concrete is limited because of their low permeability. Compared to curing the traditional concrete members, CO2 curing of pervious concrete is expected to sequester more CO2 due to the well-connected pore network and high permeability. In addition, studies on the effective utilization of resources found that the carbonation of recycled concrete aggregates (RCAs) prepared from the demolition building waste can improve the bonding between RCAs and the cement matrix. In this study, we propose to combine two carbonation steps (carbonation of RCAs and carbonation of precast pervious concrete) together to improve concrete quality and maximize CO2 sequestration in carbonated concrete. The preliminary experimental results show that the amount of CO2 captured by the carbonated pervious concrete with carbonated RCAs is higher than the normal concrete. Compared with non-carbonated RCAs, the strength of concrete with carbonated RCAs is improved. These results prove to a certain degree that the way of using the carbonation method to massively produce the precast pervious concrete is a feasible approach to mitigate carbon footprint of cement industry without scarifying the property of pervious concrete.