Fiber Effect On Bond Behaviour Between Bars And Self-Compacting Concrete Matrix

In recent years, fibre-reinforced polymer (FRP) bars or strips have been proposed as the main reinforcement for reinforced concrete members.This type of bar is suitable for overcoming the corrosion issue posed by ordinary steel bars especially in some exposed conditions that cause marked deterioration. FRP bars have many distinct advantages over steel reinforcement including high durability, good fatigue properties, high tensile strength, light weight, electromagnetic neutrality and ease of handling. The structural advantages requie the FRP and the concrete to bond well to ensure they work together. Bond behaviour is a critical issue for their successful application as reinforcement in concrete structure.On the other hand, the marked brittleness with low tensile strength and strain capacities of concrete can be overcome by the addition of fibers. Fibre reinforced concrete has been used throughout the world in pavements and slabs on ground, since some properties, such as tensile, flexural strength, fatigue endurance, impact resistance, capacity of inhibiting crack and energy absorption are substantially improved. On the basis of above circumstances, our research seminar concentrates on the effects of fibres on bond behaviour between FRP bars and concrete while fibres exerts their advantages to concrete.In terms of experiments of our research seminar, my major contributions are summarized as follows:(1). Because concrete matrix applied to the experiment is self-compacting concrete,it is necessary to conduct some research on workability and mechanical properties of self-compacting concrete to be used in the experiment, including effects of different types of fibres on workability and mechanical properties of self-compacting concrete.(2). Based on the results of the pullout tests, the influences of types of fibres, embedment length, bar diameter on bond behaviour between steel bars and concrete have been investigated and studied.(3). Based on the test results and former work, existing bond-slip constitutive relation models of FRP reinforced concrete have been analysed and veryfied, and a new equation of modified constitutive relation model applied to fibre concrete has been proposed. Its curves correspond with the test curve well. Meanwhile, values of parameter in modified constitutive relation model have been acquired. According to the my research, it show that mixing steel fibres or PP fibres with concrete has negative effects on workability of self-compacting concrete; PP fibres improve bond behaviour between rebar and concrete more greatly than steel fibres;compare to steel bars, fibres have more powerful effects on bond behaviour between GFRP bars and concrete; modified constitutive relation model curves correspond with the test curves well and values of "m" seem to be increasing with mixing more fibres into concrete.