Experimental study on the performance of ECC-ordinary concrete-steel bar cooperative bonding interface in link slab structure

In view of the problem that the interface between ECC and ordinary concrete is often encountered in the process of concrete structure construction or reinforcement and reconstruction, In the link slab, ECC with better tensile performance is often used in the link slab, while ordinary concrete is used in the pavement. Therefore, there will be a bonding interface between ECC and ordinary concrete, and this interface is the weakest interface. This paper studies the influencing factors and working mechanism of the bonding interface performance when ECC-ordinary concrete-steel bar works together in the link slab. The factors are analyzed and evaluated by the splitting tensile strength and interface failure mode of the bonding interface.The results show that in the test group, as the average roughness of the interface increases, the splitting tensile strength of the bonding interface gradually increases. The average roughness of the interface increases from 2 mm to 6 mm, and the splitting tensile strength increases from 4.25 MPa to 5.83 MPa, an increase of 29.4%. When using clean water interface agent, the splitting tensile strength is 5.04 MPa, while using cement paste interface agent, the splitting tensile strength is 1% lower than that of clean water interface agent, while using cement mortar interface agent is 14.7% higher than that of clean water. With the increase of the volume content of ECC fiber, the splitting tensile strength of the bonding interface gradually decreases. When the volume content of ECC fiber increases from 1% to 3%, the splitting tensile strength decreases from 6.24 MPa to 4.49 MPa, a decrease of 28.1%.According to the test results, the prediction formula of splitting tensile strength of bonding interface is established by statistical regression for ECC-ordinary concrete-steel bar cooperative bonding interface, which can accurately measure the splitting tensile strength of bonding interface of ECC-ordinary concrete-steel bar composite specimen.This will provide reference and strength prediction for the bonding effect of ECC and ordinary concrete at the post-pouring belt of seamless assembly link slab in the future, which can well prevent the tensile cracking of the bonding interface at this weak point, and provide reference for other similar bonding structures.