The Investigation of Interlayer Water on the Drying Deformation of C-S-H: An ANN-Assisted MD Simulation Approach

Drying shrinkage of the hardened cement mixture plays an important role in the durability of cementitious structures. However, the drying behavior of the cement paste remains unclear at the nanoscale. In this study, the effect of interlayer water on the drying deformation of C-S-H was investigated at the globule level (10^-10-10^-8m) via an artificial neural network-assisted molecular dynamics simulation approach. The present work revealed two drying deformation mechanisms of C-S-H from the perspective of the nanoscale and determined the transition threshold as RH ≈ 55%. Moreover, NaCl in the interlayer water was found to have a deleterious effect on the drying shrinkage at the nanoscale. Adding 25 wt % NaCl can increase the drying shrinkage to 54.3%. Overall, a prediction model with high accuracy was established to analyze the drying deformation of C-S-H under different moisture conditions, which explores the drying behavior at the nanoscale and paves the way for the multiscale application of drying shrinkage mitigations.