Interaction between demulsification, curing of waterborne epoxy resin emulsions and cement hydration

Cement-based repair materials modified with waterborne epoxy resin (WER) emulsions has attracted attention owing to their excellent bonding and durability properties. The coalescence of cement and WER emulsion involves complex physical and chemical interactions, especially the effect of cement hydration on the curing of WER emulsion, which needs further study. Herein, the influence of the cement hydration environment on the demulsification and curing of WER emulsion was studied by using cement pastes' centrifugal liquid. Then, the influence of waterborne epoxy emulsion on cement hydration and microstructure was analyzed. In addition, silica sol is used to compensate for the delayed effect of WER emulsion on the cement hydration. The results show that the high ion concentration environment in the centrifugal liquid of cement pastes reduces the stability of WER emulsion, the reduction of repulsion between colloidal particles could accelerate the demulsification and fusion of emulsion. Therefore, the curing process of WER emulsion was accelerated. The adsorption and complexation of WER emulsions to calcium ions promote cement hydration. When the content of the WER emulsions exceeds 5 %, the polymer film exhibits a more apparent wrapping effect on the cement particles, delaying the cement hydration. The volcanic activity of silica sol can effectively compensate for the delaying effect of WER emulsion on cement hydration. The combination of WER emulsion and silica sol-modified cement forms a uniform interpenetrating network composite structure, considerably improving the properties of cement-based materials.