Effects of the hydration process on kinetics of carbonation of lime

Research on the carbonation step in the cycle of Ca-rich lime is crucial to understand its applications in modern construction as well as in cultural heritage conservation. While studying this process, one can notice that the details of the hydration process of Ca(OH)2 play an important role in the carbonation process that follows it. There is work on the process of crystallization of Ca(OH)2 and its conversion to Ca(CO)3, but not so many implications of how the water molecules interact during the process of hydration.

Following the work of J. Park et al., we want to see how the reaction between Ca(OH)2 and water molecules later affects its carbonation, from a kinetic point of view and is there really the step of “water intercalation” between the layers of calcium hydroxide upon its hydration.

For this preliminary research, we have used hydrated lime, which was fully dried, so we can avoid any former hydration. Later, the material was hydrated in two different ways, the first one being exposure of the material to water vapor (closed system with around 90% of relative humidity), in the absence of CO2, for 7 days. The second method was immersing the sample directly into lime water (saturated solution of Ca(OH)2), letting it to react for one hour. After hydration process, XRD analysis was done for both samples. Later on, carbonation process will be tested for both types of hydrated Ca(OH)2, with the means of TGA and SEM analysis.