Date of Graduation

2009

Document Type

Thesis

Degree Type

MS

Committee Chair

P. V. Vijay

Abstract

Recent advances in Polymer Modified Concrete (PMC) have enhanced its use in civil infrastructure. These advances are related to improved properties of adhesion, abrasion resistance, impact and flexural strength, durability, and permeability. Similarly, development of lightweight, high strength to weight ratio, corrosion resistant, electromagnetically transparent FRP bars with better fatigue performance have made them an excellent alternative to conventional steel bars for reinforcing several types of concrete structures. In this study, performance of nanoclay GFRP bar reinforced in PMC evaluated. This evaluation was achieved through flexural beam test, cylinder pull out test, tension test, aging study and scanning electron microscopy (SEM). The polymer used in this study was AKKRO-7T (acrylic latex). GFRP bars were manufactured using manual pultrusion process. The constituents of GFRP bar were vinyl ester resin, 4% nanoclay and E glass fibers. Fiber volume fractions of the GFRP bars were 39.44% and 23.375% for #4 and #6 bars respectively. GFRP bars of size #4 and #6 were used to prepare beams (6 in x 12 in x 120 in), cylinder pull out specimens (6 in x 12 in; embedment length-3 in), and axial tension specimens (bars embedded in PMC prisms). Different conditioning schemes used for aging of specimens were alkaline bath at room temperature (RT), water at 140˚F, and cold temperature chamber of -20˚F. Bars (#4) encased in PMC prisms conditioned in alkaline solution up to 9 months showed a maximum reduction of 1% in tensile strength than the non-aged ones, which is statistically insignificant. Bars (#4) subjected to different aging schemes (water at 140°F and cold temperature bath at -20°F) showed higher bond strength than the non-aged ones, which was attributed to swelling effects between bar and concrete including post curing effects (maximum strength increase of 16.7% for specimens aged in water at 140°F and 13.982% for specimens aged in cold temperature bath at -20°F). The experimental to theoretical ultimate load ratio and deformability factors of the beams with #4 bars were 0.927 and 14.2, while that of beam with #6 bar were 0.9671 and 16 respectively, which is similar to other GFRP reinforced beams. The effect of temperature on the curing of GFRP specimens was studied using dog bone coupons manufactured and cured at 120˚F, 140˚F, 150˚F, 160˚F and 180˚F. The dog bone specimens showed a strength increase with elevated temperature curing (65.37% more than the one at room temperature). The increase in the strength is attributed to additional curing and better interfacial bond development at elevated temperatures. Scanning Electron Microscopy (SEM) showed GFRP bars conditioned in water at 140°F and alkaline solution showed pulling out of fibers, micro cracks and extensive damages at edges. Differential Scanning Microscopy (DSC) indicated increase in the Tg of 15.11% for GFRP bars aged in water at 140°F and 70.6% in GFRP dog bone specimens cured up to 180°F.

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