Structure, Dynamics, and Mechanical Properties of Cross-Linked Calcium Aluminosilicate Hydrate: A Molecular Dynamics Study

C-A-S-H is the main hydration product of environmental friendly concrete with cement material partially substituted by the industrial waste. The molecular structure of C-A-S-H gel determines the durability of the material. In this study, the cross-linking C-A-S-H models with Al/Si ratios of 0, 0.05, 0.10, 0.15, and 0.2 are constructed, and the structure, reactivity, and mechanical properties of the C-A-S-H gel are investigated by the reactive force field molecular dynamics. The incorporation of aluminate species in the C-A-S-H gel modifies the silicate-aluminate skeleton and interlayer water molecules. On the one hand, the bridging silicate tetrahedron is substituted by the aluminate species that polymerize with defective silicate chains, improve the crystalline order, enhance the Q species connectivity, and transform the layered C-S-H structure to cross-linked branch of C-A-S-H gel. On the other hand, the Al–Si substitution enhances the reactivity of the bridging oxygen sites in Si–O–Al, which contribute...