Weathering properties of CO2-cured concrete blocks

Steam curing of concrete blocks is an energy extensive process and contributes to a significant portion of the block production cost. CO2 curing of concrete blocks consumes CO2, reduces energy consumption and produces dimensionally more stable products. This study investigated the strength development and weathering properties of steam- and CO2-cured full size lightweight concrete blocks. Some freshly molded lightweight concrete blocks were taken from a block manufacture plant and cured in a CO2 curing tank in lab. Steam-cured lightweight concrete blocks were randomly taken from the same plant. Several hundreds of concrete blocks after steam and CO2 curing were stockpiled outside for winter exposure. The compressive strength of CO2-cured blocks was similar to that of steam-cured ones. It continued to increase when blocks were placed in a moist environment after steam and CO2 curing. However, steam-cured blocks showed faster strength development rate than CO2-cured ones did, and they behaved the same during the outdoor winter exposure, CO2-cured blocks demonstrated lower drying shrinkage and water absorption than steam-cured ones after 180 days of outdoor winter exposure. This indicated that CO2-cured concrete blocks had better dimensional stability, but similar weathering properties to steam-cured ones.

► Full-size masonry concrete blocks were cured with CO2.
► The strength of CO2 cured blocks is similar to that of steam cured blocks.
► The strength of block continues to increase in a moist environment after CO2 curing.
► CO2 cured blocks still demonstrate lower drying shrinkage and water absorption than steam cured blocks.