Regulation and mechanism of water-cement ratio and superplasticizer on rheological properties of waterborne epoxy resin emulsion modified cement paste

Waterborne epoxy resin emulsion (WER) modified cement-based materials have emerged as excellent materials for concrete repair. The regulation of its rheological properties is a critical engineering application. This study regulated the rheological properties and static structure development of WER modified cement paste through the water-cement ratio and superplasticizer, while elucidating the underlying mechanisms. The research results show that the WER-modified cement paste demonstrated a progressive reduction in yield stress, plastic viscosity, thixotropic and adhesion properties with increased water-cement ratio and superplasticizer dosage, while also slowing down the build-up of the paste structure, especially superplasticizer. The formation and evolution of the composite flocculent structure created by WER particles adsorbing onto the surface of cement particles determine the rheological properties of the WER modified cement paste. The water-cement ratio modulates cement particle spacing and surface charge through packing and dilution effects, thereby restructuring the flocculated architecture and ultimately enhancing the rheological performance of cement paste. Comparatively, steric hindrance and competitive adsorption of the superplasticizers in cement particles-WER colloidal particle system are recognized as more effective strategies for optimizing the rheological performance of cement paste.