1 Introduction
For decades, fiber reinforced polymers (FRP)
composite materials such as aramid, carbon and
glass in sheets or plates form have been used as
repair and strengthening materials due to their high
strength to weight ratio with excellent corrosion
resistance [1].
In recent, several researches on pull-off bond
behavior and performance between FRP composites
and concrete have been carried out [2, 3, 4]. Maerz
et al. [2] has conducted experimental tests to
evaluate the performance of the Dallas county bridge
in Missouri, USA, by strengthening the bridge with
the FRP composites prior to testing [2]. In order to
evaluate the long term performance of the
strengthened bridge with FRP composites, the pulloff
tests were carried out for every 6 months up to
date [2]. The results represented that all 10 samples
obtained from the pull-off tests to date failed at the
FRP sheet and coated epoxy interface [2]. In
addition, the average failure loads for the 10 samples
were around 43kN [2].
Winters et al. [3] investigated an enhancement in
bond strength of FRP composite bonded to concrete
structures with partially submerged pillars.
Although this study focused on the method itself,
they carried out 151 pull-out tests in accordance
with ASTM D 4541 [8] by utilizing an Elcometer
106 adhesion tester [3]. A 0.1 × 0.1 m grid was
drawn and 83 pulled-out tests were carried out above
the waterline and the rest 68 pulled-out tests were
1 IntroductionFor decades, fiber reinforced polymers (FRP)composite materials such as aramid, carbon andglass in sheets or plates form have been used asrepair and strengthening materials due to their highstrength to weight ratio with excellent corrosionresistance [1].In recent, several researches on pull-off bondbehavior and performance between FRP compositesand concrete have been carried out [2, 3, 4]. Maerzet al. [2] has conducted experimental tests toevaluate the performance of the Dallas county bridgein Missouri, USA, by strengthening the bridge withthe FRP composites prior to testing [2]. In order toevaluate the long term performance of thestrengthened bridge with FRP composites, the pullofftests were carried out for every 6 months up todate [2]. The results represented that all 10 samplesobtained from the pull-off tests to date failed at theFRP sheet and coated epoxy interface [2]. Inaddition, the average failure loads for the 10 sampleswere around 43kN [2].Winters et al. [3] investigated an enhancement inbond strength of FRP composite bonded to concretestructures with partially submerged pillars.Although this study focused on the method itself,they carried out 151 pull-out tests in accordancewith ASTM D 4541 [8] by utilizing an Elcometer106 adhesion tester [3]. A 0.1 × 0.1 m grid wasdrawn and 83 pulled-out tests were carried out abovethe waterline and the rest 68 pulled-out tests were
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