Effect of natural zeolite on water distribution and migration in low water/binder cement-based composites (LW/B-CC) mixed with seawater: An experimental and computational investigation

This study focus on dynamic characteristics of water distribution and migration in low water/binder cement-based composites (LW/B-CC) mixed with seawater and natural zeolite based on experimental and numerical approaches. More exactly, micro/macro properties of LW/B-CC are investigated by experiments and then the mechanism of water migration is analyzed by molecular dynamics methodology. The results reveal that the internal curing effects reflected by 1H nuclear magnetic resonance (NMR) and shrinkage test indicate that porous zeolite alleviates the self-desiccation of LW/B-CC matrix, especially in seawater-mixed LW/B-CC. Besides, the use of seawater improves the interfacial transition zone (ITZ) between zeolite and matrix. Molecular dynamics simulations exhibit an enriched ion content at the zeolite-water interface, which tends to block the transportation of water molecules. Meanwhile, the migration of water molecules is more efficient in Na-heulandite induced by a more equal distribution of extra-framework charges. With evidence from experimental and numerical ap-proaches, ions in seawater are confined by the lattice of zeolite, and more water can be stored in the pores of zeolite and used as internal curing water; hence, zeolite is an appropriate type of aggregate for producing LW/B-CC incorporating seawater.