Carbon dioxide absorption and durability of carbonation cured cement and concrete compacts

Intensification of the greenhouse effect from anthropogenic emissions of carbon dioxide and other greenhouse gases have, and will continue to increase the Earth's average global temperature. Intergovernmental demand to minimize human's influence on the global climate was entered into force in 2005, requiring participating industrialized countries to reduce collective greenhouse gas emissions by 5.2% compared to 1990 values. Along with clean energy and efficient system design, carbon dioxide sequestration becomes one of the critical measures in global greenhouse gas mitigation exercises.Carbon dioxide sequestration through carbonation curing of concrete has the potential to reduce atmospheric carbon dioxide emissions. In the presence of water, carbon dioxide gas readily reacts with the calcium silicate compounds of cement to form calcium carbonate. In this manner, early-age concrete exposed to recovered carbon dioxide could be used as a sink for CO2 storage. The focus of this study was to investigate the potential for carbon dioxide sequestration through carbonation curing of cement paste and concrete compacts, as well as their durability performance in structural applications.To determine the feasibility of such a method, research was conducted on the carbon dioxide absorption potential and durability of carbonation cured concrete products. Carbonation curing was characterized by the mass of carbon dioxide absorbed, mass of water lost, peak sample temperature, dimensional stability, compressive strength, depth of carbonation and microstructure. Further testing was performed on the carbonation cured products to assess the long-term durability. Long-term durability was characterized by the mass of carbon dioxide absorbed, dimensional stability, freeze/thaw resistance and compressive strength in simulated service exposure. Carbon dioxide absorption in the order of 10% by mass was recorded during early-age carbonation curing. Weathering carbonation shrinkage of concrete samples was reduced by approximately 33% in carbonated samples as oppose to those hydrated. It was also found that carbonation curing reduced the mass loss during freeze/thaw durability testing by 90% over hydration curing