Mechanical and interface bonding properties of epoxy resin reinforced Portland cement repairing mortar

•An ordinary Portland cement repairing mortar enhanced by aqueous epoxy resin was prepared.•Flexural strength and flexural toughness were increased irrespective of epoxy resin dosages.•An optimal dosage of epoxy resin exists for improving different interface bonding strengths.•Both compressive strength and flexural toughness influence interface bonding performance. An aqueous epoxy resin with four different dosages was employed to enhance ordinary Portland cement (OPC) mortar for the first time used as a polymer-cement repairing material. Experimental results showed that the flexural toughness of the epoxy resin modified OPC mortar was obviously improved without losing too much compressive strength. In addition, three different interface bonding strengths used for evaluation of the interface bonding properties were all enhanced with certain dosages of epoxy resin. For instance, the interfacial flexural bonding strength, direct interface shear strength and interface tensile strength of the OPC mortar with epoxy resin dosage at 5% was increased by approximately 16.7%, 29.8% and 6.9% respectively compared to the control mortar without epoxy resin. It is assumed that the epoxy resin formed as polymer films which could improve the microstructure of OPC mortars as evidenced by scanning electron microscopy analysis via integrating different components in binder matrix and crack bridging effect is the main reason for the related improvements. Thus, this newly developed OPC mortar reinforced by suitable contents of aqueous epoxy resin is a promising repairing material for mitigating deteriorations of concrete which awaits further applications.