Cements made of reactive magnesium minerals ("reactive magnesium cements", a.k.a. RMCs) have been proposed as alternative building materials to common Portland cement. RMCs are considered to be "negative emission" or "carbon-sequestering" cements, because they (1) avoid the CO2 emissions normally associated with portland cement, and (2) passively uptake atmospheric CO2. Thus, large-scale implementation of RMCs could thus help to reduce climate change impacts associated with cement usage in construction.
Upon initial mixing, RMCs are porous and relatively weak, but over time, and with exposure to water and atmospheric CO2, RMCs react to form stable magnesium-carbonate solids within the pore structure of the original cement skeleton. The formation of carbonates strengthens the cements, but can also clog the pore space and limit complete reaction. This project aims to use state-of-the-art, high resolution, 3D X-ray computed tomography (X-ray CT) to characterise the evolving structure of RMC materials over months-long time frames. The overall goal of the project is to optimise cement composition and initial structure such that the RMCs enhance CO2 uptake and cement strength while also minimizing clogging.