Materials characteristics affecting CO2 curing of concrete blocks containing recycled aggregates

In order to enhance the CO2 curing efficiency of concrete block prepared with recycled aggregates, several material characteristics of the concrete block including moisture content, bulk density, aggregate to cement ratio, recycled aggregate content and types of binders, were studied experimentally to assess their effects on the CO2 curing process. The results indicated that, during 2 h of CO2 curing period, the moisture content and aggregate to cement ratio of the prepared blocks had significant effects on the CO2 curing degree and the compressive strength. Appropriate pre-drying of the block specimens before CO2 curing enabled the maximum curing degree, and the compressive strength attained was comparable or superior to that of the 6 h steam cured blocks. The bulk density and recycled aggregate content of the prepared blocks would also influence the CO2 curing degree, but their effects on compressive strength were more complex. It was confirmed that the presence of recycled aggregate in the concrete blocks can promote the CO2 curing efficiency.