Mechanical Properties of Newly Developed Heat-Resistant FRP Bars

Abstract

This paper presents a basic research into newly developed heat-resistant fiber reinforced polymer (FRP) bars. The heat resistance of commercially available FRP bars is low because of the low heat resistance of the resins used for the matrix such as epoxy (EP), unsaturated polyester (USPE) and vinyl ester (VE). The authors investigated new heat-resistant resins suitable for the production of FRP bars, and resol type phenolic (PH) and M type cross-linked polyester-amide (CP) resins were selected for bar fabrication and testing. Six different types of FRP bars made with carbon fiber or aramid fiber and PH, CP or EP matrix resin were prepared. The heat resistance of each bar was evaluated by tensile tests during and after heating. To assert the durability of the bars, an alkaline resistance test was performed. Pull-out tests and flexural tests of concrete members reinforced with the newly developed FRP bars and those with steel bars were also performed at normal temperature (20°C) and high temperatures. The test results indicate that the heat resistance of the FRP bar specimens made with PH or CP matrix resin was higher than that of the specimens made with EP matrix resin, and that the heat resistance of reinforcing fiber was essential for improvement of the heat resistance of the matrix resin. Of particular note is the fact that the heat resistance of FRP bars made with carbon fiber and PH matrix resin was found to be almost the same as that of steel bars.