The waterproofing effect and mechanism of graphene oxide/silane composite emulsion on cement-based materials under compressive stress

• The waterproofing effect of GS composite emulsion on cement-based materials under compressive stress was investigated. • GS combines with calcium silicate hydrate to form the hydrophobic layer. • GS reacts with calcium hydroxide to generate calcium silicate hydrate. • The influence of the water-to-binder ratio and stress ratio on the hydrophobic properties of GS was analyzed. The influence of the water-to-binder ratio and compressive stress on the waterproofing effect of graphene oxide/isobutyltriethoxysilane (GS) composite emulsion on cement-based materials was investigated. The results show that GS combines with calcium silicate hydrate to form a hydrophobic film, which prevents the intrusion of external water and carbon dioxide. In addition, after undergoing self-condensation, silanol reacts with calcium hydroxide to generate calcium silicate hydrate gel, which improves the microstructure of cement-based materials. Furthermore, the increase in the water-to-binder ratio and stress ratio leads to the expansion and connection of the pore structure of cement-based materials, resulting in an increase in the capillary water absorption coefficient. Meanwhile, the higher porosity is conducive to the penetration of the emulsion in cement-based materials and the formation of a waterproof layer. Thus, the waterproofing effect of GS composite emulsion on the specimen was improved.