Tracing Polymerization in Calcium Silicate Hydrates using Si Isotopic Fractionation*

Silicate-chains polymerization is a crucial process in calcium silicate hydrate minerals, with large relevance for improving the durability and reducing the environmental impact of cement-based materials. To better understand the evolutionary mechanisms underlying the polymerization of silicate-chains in layered calcium silicate hydrates, we propose to trace the evolution of the polymerization degree by using silicon isotopes^{[1 ]}. We show that the Isotopic fractionation tool is able to discern not only between the polymerization order of calcium silicate hydrate minerals but even between cement gels suffering calcium leaching^[2]. Silicon isotopic fractionation can, therefore, be used to improve the sustainability of concrete along its lifetime in the quest for green cement^[3].

[1]R. Dupuis, M. Benoit, M. Tuckerman and M. Méheut, Accounts of Chemical Research (2017) 1597–1605
[2]R. Dupuis, J. S. Dolado, J. Surga, A. Ayuela, Geochimica Cosmochimica Acta (submitted)
[3]A. Ayuela, et al. The Journal of Chemical Physics (2007) 127