Potential for Carbon Dioxide Absorption in Concrete

Anthropogenic releases of carbon dioxide are being studied with respect to the global carbon dioxide cycle. Concrete, the most used building material in the world, contributes to these releases significantly in the manufacturing of cement, both from energy use and from the calcination chemical process. The reverse process, carbonation, in which the hydrated cement reacts with carbon dioxide to form calcite, is being studied under many different circumstances for its potential to balance this release by sequestering carbon dioxide. This research focuses on other carbon dioxide sequestration species within concrete. It is hypothesized, and has been shown in some cases, that many other dissolved carbon dioxide complexes exist within the cement paste matrix, as they do in many aqueous-based systems and also that carbonate species other than calcite may exist. It is shown that carbon dioxide species, other than calcite, do exist in cement paste samples in amounts that are significant with respect to the stoichiometric potential for reversing the calcination process.