Michal Hlobil, 2010
Bond Properties of GFRP Reinforcement and Concrete after Freeze / Thaw Cycles
Abstract
Bond properties between concrete and reinforcement are very important, because they ensure the same strain in materials and transfer of stress between them. The bond strength depends on the interlocking between the reinforcement and concrete matrix, sufficient concrete cover and on the same coefficient of thermal expansion of materials. These factors are well documented for steel, but not for internal Glass Fibre Polymer (GFRP) reinforcement. This work provides experimental results of bond properties between GFRP rebars and concrete. Seven 1,8 m long beams reinforced with GFRP were tested during the experimental procedure. To be able to assess the bond properties, the beams were reinforced with non-continuous rebars with a 150 mm overlap in the middle of each beam. Three beams were placed in a climatic chamber for fifty days and exposed to cycles of freezing and thawing with temperatures from –30 to +40 °C. One cycle of freezing, thawing and repeated freezing lasted 24 hours. The remaining four beams were cured in laboratory environment. Afterwards a four point bending test was performed on all beams and the load bearing capacity and crack formation was compared. The results indicated that fifty F/T cycles had no significant impact on the behaviour of the tested beams in terms of moment capacity or crack propagation.
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