Quantifying Drying and Carbonation in Calcium Silicate Cement Systems Using Neutron Radiography

Calcium silicate cements react with carbon dioxide (CO2) to form a concrete-like product. While several papers have focused on the properties of the solid material that forms, this study investigates the processing of carbonated calcium silicate systems. Specifically, this paper examines the drying of fresh calcium silicate cement/ water systems and the subsequent carbonation process. A new methodology is presented, based on neutron radiography, to quantify the drying and extent of carbonation that has occurred (degree of carbonation) and the spatial distribution of carbonated products within the sample. Mortar mixtures with high-purity calcium silicate-based cement significantly extend the initial drying period, enabling greater penetration of CO2, allowing it to react with the calcium silicate at greater depths in the sample. While the carbonation reaction is rapid immediately after the CO2 is introduced into the system, the carbonation reaction slows over time. The findings indicate that the degree of saturation and the potential formation of reaction products may limit the penetration of CO2 through the sample depth.