Benefits of Grooving on Vacuum-Assisted Resin Transfer Molding FRP Wet-Out of RC Beams

Abstract

Fiber-reinforced polymer (FRP) externally bonded to RC beams is commonly applied by hand layup. Vacuum-assisted resin transfer molding (VARTM), a novel application method in infrastructure, can produce FRP with more-consistent quality and uniformity. Additional steps are required, however, which can increase the application time and cost. This research will investigate the reduction of VARTM wet-out time achieved by sawing grooves into the concrete surface. Fiber-reinforced polymer U-jackets are applied by VARTM to beams with vertical grooves. The wet-out of the beams is recorded and timed. Results indicate that beams with 3.2-mm-deep grooves achieve 95% wet-out in an average of 200 s. This is only 22% of the time it takes to wet-out a beam with no grooves, an average of 911 s. A wet-out mechanism based on a modified Darcy’s law is presented to verify the results. Darcy’s law predicts that time savings increase exponentially with the length that the epoxy has to travel, which indicates that a significant amount of time could be saved on actual girders.