Experimental evaluation of bond behavior of reinforcing bar in plain and fibre reinforced concrete

Abstract

To minimise the test errors due to uneven contact pressure and friction, the pull out test setup has been redesigned by inserting a rubber pad and a polytetrafluoroethylene (PTFE) film at the interface in previous research. The effectiveness and appropriateness of the new test setup are herein verified experimentally. Using the redesigned test method with the rationalised setup, pull out tests of reinforcing bars in plain concrete and fibre reinforced concrete (FRC) were conducted. The results were compared to those obtained from the conventional test method without the use of rubber pad or PTFE film. The redesigned test method yielded lower and less variable bond strength and stiffness, and is confirmed to give more realistic and reliable bond properties for structural analysis and design. As confirmed by the test results, the FRC specimens demonstrated superior bond properties to plain concrete specimens.