The performance of reactive powder concrete (RPC) is much higher than that of ordinary concrete, and the engineering application is gradually increasing. The bond failure process and bond slip between RPC and reinforcement will show new characteristics. It is necessary to study the bond behavior between RPC and steel bar. The direct drawing test was carried out on the 36 bonding specimens in order to study the bond performance between steel bar and reactive powder concrete. The research shows that the cohesive force consists of three parts: the mechanical bite force produced by the mechanical occlusion between the reinforcing rib and the RPC; The cementing force produced by chemical reaction between RPC component and surface material of reinforcement; Friction between reinforcement and surrounding RPC. The application of ultrahigh strength and various cementitious materials make the Bonding strength between rebar and RPC significantly higher than that of normal concrete. This study can provide reference for the reinforcement anchorage design of RPC structure.

Uniaxial compression tests were carried out on RPC with different steel fiber contents. The mechanical properties of RPC and the compressive-stress-strain curves of RPC with different steel fiber contents were studied. The results show that under the same mixture proportions, compressive strength increase with the increase of steel fiber content. When the steel fiber content is 3.5%, the compressive strength of RPC cubes is the largest; under the same mixture proportions, the compressive strength of RPC cube is approximately linear with the compression strength of prism, and the peak compressive strain and elastic modulus ratio of RPC cubes increase with the increase of steel fiber content. In this paper, the equation of the rising and descending sections of the stress-strain curves of different steel fiber volume admixtures is derived. According to the results of this test, the relationship between rising section, descending section coefficient and steel fiber content is obtained.)

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In order to investigate the bonding performance between reactive powder concrete (RPC) and normal concrete (NC), nine groups of RPC-NC composite specimens were designed for double-sided shear based on the orthogonal test. The test parameters include interface roughness, RPC water binder ratio and steel fibre content. The results show that the roughness is the most important factor to affect the bond shear strength, followed by RPC water binder ratio, and steel fibre content has the least influence. In the range of 2.11mm ~ 6.01mm average sand filling depth, the bonding strength of RPC and NC with the same water binder ratio increases with the increase of interface roughness. The average bonding strength of 0.22 water binder ratio group is the highest, and it is 7.6% and 28.3% higher than that of 0.24 and 0.20 groups, respectively. Based on the test results, the prediction formula of the bond shear strength of RPC-NC considering the interface roughness and the water binder ratio of RPC is established.