Experimental Study On Bonding Property Between The Hybrid Fiber Reinforced Concrete And Existing Concrete

Hybrid fiber reinforced concrete(HFRC)is a new type of composite material in which two or more different types or shapes fibers are mixed into concrete.It has good resistance to compression,cracking and improving structural durability.When hybrid fiber reinforced concrete is used as repair material,in order to guarantee the quality of repair and reinforcement,it is of practical engineering significance to study its bonding property with existing concrete.This paper aims to study mechanical properties of fresh HFRC and interfacial bonding properties and interfacial microscopic characteristic between hybrid fiber reinforced concrete and existing concrete.The main research results are as follows:(1)Study on the basic mechanical properties of the fresh HFRC.In this paper,12 groups of 150 mm × 150 mm × 150 mm cube specimens were tested for compressive strength and splitting tensile strength,when the volume content of steel fiber is 0.8% or1.2%.The influence of the addition the volume content of polypropylene fiber is 0.11%on the compressive and split tensile strength.The results showed: adding fiber can improve the mechanical properties of concrete to a certain extent,the damage pattern of concrete has been improved.(2)Study on the splitting tensile test of bonding specimens between the HFRC and existing concrete.In this paper,12 groups of 150 mm × 150 mm × 150 mm bonding cubes were tested for splitting tensile strength,research on the effects of steel fiber,polypropylene fiber,steel-polypropylene hybrid fiber and epoxy interface agent on bonding strength.The bonding effect is evaluated based on the relative bond splitting strength.The results showed: mixing hybrid fiber and planting epoxy interface agent can improve the cube splitting tensile strength of the bonding specimen effectively.(3)Study on the slant shear test of bonding specimens between the HFRC and existing concrete.In this paper,12 groups of 100 mm × 100 mm × 300 mm bonding prisms were tested for the slant shear strength,research on the effects of steel fiber,polypropylene fiber,steel-polypropylene hybrid and fiber and epoxy interface agent on bonding strength.According to ACI 546R-04,the bonding effect was evaluated.The results showed: mixing hybrid fiber and planting epoxy interface agent can improve the slant shear strength of the bonding specimen effectively.(4)Study on the action mechanism of hybrid fibers on the bonding surface,through the slice of hybrid fiber bonding specimen,analyzing the fiber-concrete matrix by SEM,investigating the mechanism of action of hybrid fiber on the bonding surface.The results showed: mixing fiber has positive effect on bonding strength.