Experimental study on the fire resistance of RC beams strengthened with near-surface-mounted high-Tg BFRP bars

A lack of knowledge regarding the fire resistance of fiber reinforced polymer (FRP) reinforced/strengthened concrete structures has impeded the wide acceptance and use of these materials. This paper presents the results of both mechanical property tests performed on basalt FRP (BFRP) bars during and after exposure to high temperatures and the fire resistance of reinforced concrete (RC) beams strengthened with near-surface-mounted (NSM) high-Tg BFRP bars. Experiments were conducted on 108 effective tensile test specimens and 7 four-point bending beam specimens. The results indicate that a resin matrix with a higher Tg value and good compatibility after pultrusion curing process with fiber were very useful for improving the heat resistance of FRP bars, meaning that NSM FRP strengthened RC beams could exhibit improved fire resistance. The FRP bars maintained sufficient anchorage if only two ends of the NSM FRP bar were protected against fire by stretching them into supporting components or wrapping them with U-shaped fire protection boards. The NSM high-Tg FRP strengthened RC beams could potentially exhibit the same level of fire resistance as the RC beams. These preliminary conclusions improve the prospects of using FRP materials in engineering applications.