Hydration inhibition mechanism of gypsum on tricalcium aluminate from ReaxFF molecular dynamics simulation and quantum chemical calculation

J Zhu and DJ Shen and W Wu and BS Jin and SX Wu, MOLECULAR SIMULATION, 47, 1465-1476 (2021).

DOI: 10.1080/08927022.2021.1984463

To understand the hydration inhibition mechanism of gypsum (CaSO4 center dot 2H(2)O) on tricalcium aluminate (C(3)A), the very early hydration process of C(3)A in the presence of CaSO4 center dot 2H(2)O was investigated by ReaxFF molecular dynamics simulation and quantum chemical calculation. The adsorption propensity of H2O to the surface of CaSO4 center dot 2H(2)O and C(3)A, the penetration of H2O into CaSO4 center dot 2H(2)O and C(3)A, the diffusion of CaSO4 center dot 2H(2)O and C(3)A to H2O, and the structural changes at the interface of C(3)A were investigated by analyzing the adsorption configuration, penetration depth, diffusion distance, and the radial distribution function, respectively. The results showed that two forms of associative adsorption and dissociative adsorption were found on the surface of CaSO4 center dot 2H(2)O and C(3)A. The internal structure of CaSO4 center dot 2H(2)O was more conducive to the movement of H2O than that of C(3)A. The diffusibility of overall C(3)A was weaker than that of overall CaSO4 center dot 2H(2)O due to the cage-like structure of C(3)A. The sensitivity of the C(3)A structure was greater than that of CaSO4 center dot 2H(2)O structure to hydrolysis.

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