Intermolecular interactions of nanocrystalline alkali-silica reaction products under sorption

T Honorio and OMC Tamouya and ZG Shi and A Bourdot, CEMENT AND CONCRETE RESEARCH, 136, 106155 (2020).

DOI: 10.1016/j.cemconres.2020.106155

There is no consensus on the physical origin of alkali-silica reaction (ASR) damage in concrete. Atomic-level detail on the intermolecular interactions of ASR products with water is critical to understand the development and to propose solutions to mitigate ASR. We combine molecular dynamics and Monte Carlo simulations to model ASR products under sorption. The hydration of shlykovite, a naturally occurring phyllosilicate structurally similar to ASR products, is analyzed with atomic-level detail. Sodium and potassium, the most relevant alkali in ASR, are considered as charge balancing cations in shlykovite. Intra- and inter-layer water content and volume remain stable under sorption at ambient pressure, which corroborates that swelling of crystalline products cannot be at the origin of ASR damage. Also, we provide the effective interactions of Na- and K-shlykovite under water-saturated conditions. These potentials of mean force can be used in mesoscale simulations to test other mechanisms of ASR damage.

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