Bond of Epoxy-Coated Reinforcement: Coefficient of Friction and Rib Face Angle

Abstract

The coefficients of friction between epoxy-coated and uncoated reinforcing steel and mortar and the effects of rib face angle on the relative bond strength of epoxy-coated bars are determined. Results for 130 test specimens indicate that the average coefficient of friction is about 0.49 between epoxy-coated reinforcing steel and mortar and about 0.56 between uncoated reinforcing steel and mortar. Based on 58 beam-end specimen tests using both machined and rolled 1-in. (25-mm) nominal diameter reinforcing bars with face angles of 30, 40, 45, 60, and 90 deg, epoxy coating has the least effect on the bond strength of steel reinforcing bars to concrete when the rib face angle is greater than or equal to 45 deg.