A first-principles exploration of the hydration kinetics of alternative cements

Cement (in the form of "ordinary Portland cement", or OPC) is one of the largest industrially produced materials by mass on earth, and accounts for up to 8% of total per capita CO2 emissions globally. There is therefore a clear motivation for the development and characterization of alternative cements with comparable strength and cost, but can be manufactured with a lower carbon footprint. One promising class of materials are so-called sulfoaluminate cements such as ye'elimite - Ca4[Al6O12]SO4) arranged in a sodalite structure, which in practice are often mixed with the belite phase of OPC to form manufacturable and workable cements which reduce CO2 output by up to 20% when compared to conventional OPC. However, the reaction kinetics of ye'elimite surfaces with water is still an active area of research. Using first principles computational techniques, we explore the structural features of ye'elimite surfaces, and examine the effects of these features on the hydration kinetics. This work provides insight not just into how to control this reaction process, but into the development of other alternative cement compounds.