Interaction mechanisms between organic and inorganic phases in calcium silicate hydrates/poly(vinyl alcohol) composites

Poly (vinyl alcohol) (PVA) emulsion is commonly used in cement-based materials to obtain higher performance. The present work investigates the interaction mechanisms between PVA and calcium silicate hydrates (C-S-H) using ambient and high pressure X-ray diffraction (XRD), Si-29 magic angle spinning nuclear magnetic resonance (MAS NMR), nano-indentation, and molecular dynamics simulation. In a C-S-H nano-particle, small-size PVA molecules can be intercalated into the interlayer region of the calcium silicate sheets, lowering the interlayer incompressibility and the overall bulk modulus of C-S-H at the crystal length scale. At a larger length scale, the large-size PVA chains can be in the midst among the C-S-H nano-particles, decreasing the porosity, thus the indentation modulus of the meso-composite is improved.