Development of a new generation of eco-friendly concrete blocks by accelerated mineral carbonation

The replacement contents of coarse and fine natural aggregates by coarse and fine RCA in concrete blocks ranged from 0% to 100% by mass, respectively. The accelerated mineral carbonation of RCA and concrete blocks was processed under a gas pressure of 0.1 Bar and 5.0 Bar. The experimental results showed that incorporating the carbonated RCA in concrete blocks led to an increase in strength by 2%–18%, which can also increase the reuse rate of RCA by 35% for the concrete blocks with the required strength. Moreover, the use of the carbonated RCA in concrete blocks resulted in a lower drying shrinkage. A high CO2gas pressure and longer carbonation duration had an insignificant effect on the properties of concrete blocks when the carbonation process was extended to 24 h. It would be more efficient and economical to fabricate this type of eco-blocks by using the carbonated RCA, a low CO2gas pressure (i.e. 0.1 Bar) and a short-term carbonation (i.e. 6 h).