Effect of admixed silicone emulsion on water and chloride transport properties of concrete.

The addition of silicone is effective method for improving both surface and internal hydrophobicity of concrete, thus clarifying its effect on transport property of concrete is very important. In this study, both water and chloride transport properties of concrete incorporated with three silicone emulsions based on different active ingredients (silane oligomers or silane monomers) were evaluated and investigated. The results show that all three silicone emulsions exhibit no obvious negative effect on hydration and microstructure of cement paste; however, the admixed silicone emulsions increase both the thickness and porosity of ITZ in concrete. Therefore, the admixed silicone emulsions result in reduced compressive strength of concrete. Further, the incorporated silicone emulsions efficiently increase surface and internal water contact angle of concrete, thus mitigating both water absorption and chloride transport in concrete. Due to more pronounced interaction between silane oligomers and hydration products based on molecular dynamics simulation, the beneficial effect on improving hydrophobicity of concrete and halting water and chloride transport is more significant for the admixed silicone emulsion with silane oligomers as active ingredient. [Display omitted] • Admixed silicone emulsions show no negative effect on hydration and pore structure. • Admixed silicone emulsions increase the thickness and porosity of ITZ in concrete. • Admixed silicone emulsions increase surface/internal water contact angle of concrete. • Admixed silicone emulsions mitigate water absorption and Cl− transport in concrete. • The positive effect is more significant for silicone emulsion with silane oligomers. [ABSTRACT FROM AUTHOR]