Abstract
The use of externally-bonded fiber-reinforced polymer (FRP) sheets has been successfully used in the repair and strengthening of both the shear and flexural capacities of reinforced concrete (RC) beams, slabs and columns since the 1990s. However, the externally-bonded FRP reinforcements still present many disadvantages, such as poor performance in elevated temperature and fire, lack of permeability and strength degradation when exposed to ultraviolet radiation. To remedy such drawbacks, the fiber-/fabric-reinforced cementitious matrix (FRCM) has been recently introduced. The FRCM system consists of a fiber mesh or grid embedded in a cementitious bonding material. The present research investigates the flexural strengthening of reinforced concrete (RC) beams with FRCM. The experimental testing included eight large-scale concrete beams, 150 mm × 250 mm × 2400 mm, internally reinforced with steel bars and strengthened in flexure with FRCM. The investigated parameters were the internal steel reinforcement ratio and the FRCM systems. Two steel reinforcement ratios of 0.18 and 0.36 of the balanced reinforcement ratio, as well as three FRCM systems using glass, carbon and PBO fibers were investigated. Test results are presented in terms of load-deflection, load-strain and load-crack width relationships. The test results indicated that the PBO FRCM significantly increased the ultimate capacity of the strengthened RC beams with both low and moderate internal reinforcement ratios compared to the glass and carbon FRCM.
Highlights
Deterioration of concrete structures is a very common problem that civil engineers all over the world are facing
Significantly increased the ultimate capacity of the strengthened reinforced concrete (RC) beams with both low and moderate internal reinforcement ratios compared to the glass and carbon fabric-reinforced cementitious matrix (FRCM)
The failure mode of carbon FRCM is mainly by delamination and/or concrete, flexural capacity increased by 32% and 92%
Summary
Deterioration of concrete structures is a very common problem that civil engineers all over the world are facing. A very important and major cause of concrete deterioration is the corrosion of the embedded metals (most commonly steel) [1]. Another main cause of concrete structures’ deterioration is the exposure to harsh environments; if no protective action is taken, the damage can be significant. In Canada, more than 40% of the bridges were built 50 years ago and are in need of significant structural rehabilitation [2]. Some structures were built to carry loads that are significantly smaller than the current code requirements. Engineers need to design and evaluate strengthening methods to respond to those needs
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