2020 Volume 74 Issue 1 Pages 147-154
No study has evaluated bond strength of FRP rods in concrete under temperature of external environment fluctuates. Here it is expected that FRTP may become popular because this cost is cheaper than that of FRTS. Therefore, this study investigates bond strength of FRP rod including FRTP in concrete. First, variations of bond strength of FRTP in concrete is evaluated. That is, pull-out test is performed using each of 17 specimens to measure bond strength of FRTP or rebar in concrete. As a result, the rebar and FRTP rods have similar coefficients of variation in bond strength. Also F test judges that there is no significant difference in variation between FRTP and rebar. Secondly, influence of temperature fluctuation under 0-60℃ on bond strength of two types of FRTP and three type of FRTS is evaluated. As a result, presence or absence of water in exposure environment does not affect bond strength of FRP rod in concrete. Also it is clear that bond strengths before and after exposure are same when FRP rod whose thermal expansion coefficient is similar to concrete around 10×10－6/℃ is used. However, it is confirmed that when FRP rod with a different coefficient of thermal expansion from concrete is used, bond strength after exposure becomes lower than that before exposure. This reason seems that there is a difference in strain between FRP rods and concrete as temperature increases and decreases.
