Date of Graduation
Statler College of Engineering and Mineral Resources
Civil and Environmental Engineering
P V Vijay
In this research, glass fiber reinforced polymer (GFRP) bars were manufactured with nanoclay at CFC-WVU laboratory to evaluate mechanical properties and durability. GFRP bars (0.5 in. and 0.75 in. dia.) were manufactured at room temperature by manual pultrusion. Vinyl ester resin was used with 4% exfoliated nanoclay by weight with a 44.7% glass fiber (roving) volume. Shear mixer was used to exfoliate nanoclay in the resin. GFRP bars measuring 12 ft. long were successfully manufactured with a low void content of 0.39%.;GFRP bars manufactured with and without nanoclay were tested in tension, shear and bond prior to and after aging them in different conditioning schemes. Bars (#4 dia.) with nanoclay showed 30.04% lower average strength as compared to those without nanoclay, which suggested that addition of higher percentage nanoclay (4%) reduced the maximum failure stress of GFRP bars. Among different aging schemes (water at room temperature, water at 110°F, water at 140°F, and alkaline solution at room temperature), water at elevated temperature of 140°F was found to be more severe on strength reduction followed by alkaline aging (strength reduction of 36.51% without nanoclay vs. 18.52% with nanoclay at 140°F aging as compared to 16.35% without nanoclay and 13.58% with nanoclay in alkaline solution). GFRP bars with nanoclay exhibited better durability than those without nanoclay in all types of conditioning schemes considered in this research. Bars (#4 dia.) with nanoclay showed 5.71% lower average shear strength as compared to those without nanoclay (24.77 ksi vs. 26.27 ksi) and #6 bars with nanoclay showed 12.77% lower average shear strength as compared to those without nanoclay (20.02 ksi vs. 22.95 ksi), which suggested that addition of nanoclay decreased the shear stress. GFRP bar with nanoclay conditioned at different aging schemes showed higher bond strength than the original bond strength, because increase in bond stress was noted due to post curing of concrete and rebars including bar swelling effects. Scanning Electron Microscopy (SEM) showed that many of the GFRP bars without nanoclay exhibited fiber pull-out near edges as compared to those with nanoclay. Bars subjected to 140°F and alkaline conditioning showed more number of fibers being pulled out and/or damaged from the matrix along the edges, which causes a reduction in bond strength.;Concrete beams reinforced with nanoclay GFRP bars showed better stiffness characteristics than those with regular GFRP bars (without nanoclay). GFRP reinforced beams were cast with #4 and #6 GFRP bars with and without nanoclay. Experimental to theoretical ultimate load ratios of all the beams varied between 0.91 and 1.08 (i.e., within 10%).
Krishnaswamy, Vijayarajan, "Durability of nanoclay FRP bars for concrete members" (2006). Graduate Theses, Dissertations, and Problem Reports. 4242.