| ABSTRACT: Reactive Powder Concrete (RPC) is a kind of new cement base composite material, which provides satisfactory strength, toughness and durability; and also has high environmental protection. Due to these characteristics, it presents broad application prospects in civil engineering field. The RPC members are mostly applied to reinforcement concrete in engineering projects, in order to study the synergistic effect mechanism of steel bar and RPC; the bonding performance between deformed steel bar and RPC is investigated in this paper through beam tests, pull-out tests and inner-embedded strain-gauge tests. In order to solve the anchorage design problem in RPC members, the bond anchorage mechanism and bond anchorage strength of deformed steel bar are analyzed, which also provide the basis for the standard enaction for RPC. The main work conclusions are as follows:(1) RPC beam bonding tests are carried out by changing steel fiber volume, the thickness of protection layer and bonding length, etc. The influence of anchorage conditions on the failure mode, bond stress-slip curve, and bond characteristic values of specimens are analyzed. The result shows that anchorage conditions have a great influence on the bond performance between reinforcement and Reactive Powder Concrete. The calculation formulas of bonding strength and slip value are established throughout statistical regression of the experimental results;(2) Bond performance between reinforcement and RPC with steel fiber volumes between0.0%～2.0%are studied through beam and pull-out bond tests. The regularity of bond strength changed with steel fiber volumes under the different test methods is discussed. C40concrete beam tests are correspondingly carried out compared with the RPC specimen with2.0%steel fiber, to study the bond performance between steel bar with different concrete. Bonding mechanism of RPC has been investigated through microscopic structure analysis. This result shows that the bond strength increases with the increasing of steel fiber under the two kinds of test method, but the bond strength growth trend of beam test is greater than pull-out test. Bond strength of beam test is greater than pull-out test except for the specimens without steel fiber; meanwhile bond strength between deformed steel bar and RPC is dramaticlly higher than C40concrete; Compact structure and steel fiber in RPC lead to its high bonding strength;(3) Inner-embedded strain-gauge tests are carried out, according to measured steel bar strain, the bond stress distribution of different location is analyzed, the position function which reflects this change is deduced; and bond stress-slip constitutive model which considered bond position is established.(4) Based on above tests, bond length of deformed steel bar in RPC members with steel fiber volumes between0.0%and2.0%is conformed through anchorage reliability analysis and current specifications are put forward, this suggest can provide a basis for relevant specification of RPC. |
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