CO2 curing for improving the properties of concrete blocks containing recycled aggregates

A CO2 curing process was adopted to cure concrete blocks made with recycled aggregates. Non-load- and load-bearing blocks were prepared with 0%, 50% and 100% recycled aggregate to replace natural aggregate. The blocks were then placed in a pressurized 100% CO2 curing chamber for 6, 12 and 24 h. The temperature and relative humidity inside the chamber were monitored, and the moisture loss and CO2 curing degree were determined by a weighing method. After the curing process, the strength and drying shrinkage of the CO2 and moist cured blocks were measured. The CO2 cured blocks attained higher compressive strength and lower drying shrinkage than the corresponding moist cured blocks. However, curing time and amount of recycled aggregate present in the blocks had insignificant effects on the strength gain and CO2 curing degree.