Flexural Cracks in Fiber-Reinforced Concrete Beams with Fiber-Reinforced Polymer Reinforcing Bars

Fiber-reinforced polymer (FRP) reinforcing bars have attracted considerable attention for applications where corrosion of steel reinforcement is problematic. Due to the generally low elastic modulus and poor bond characteristics of FRP as compared to steel reinforcing bars, the use of FRP results in larger crack widths under service loads. Fiber-reinforced concrete (FRC) is proposed for use with FRP to reduce crack widths. The work presented herein includes the results from 16 beams tested under four-point bending with either Grade 420 (Grade 60) steel or FRP reinforcing bars, and either plain concrete or FRC. A modified Gergely-Lutz model was applied to the measured crack widths to calculate bond coefficients that were used to quantify the effectiveness of FRC in reducing crack widths. In the beams with steel reinforcing bars, the FRC was found to have little influence on crack widths. In the beams with FRP reinforcing bars, the FRC was found to significantly reduce maximum crack widths.