Bond of glass fiber reinforced plastic reinforcing bar for consideration in bridge decks

The use o f non-metallic bridge deck reinforcement is o f interest in regions where corrosion is a problem. A number o f manufacturers have developed GFRP rebar for this application. Because the production o f the material is relatively new, there is a great deal o f variability among the products from different manufacturers. In addition, as the manufacturers continue to develop their own product, variations in GFRP from single manufacturers have been observed. The objective o f this study was to investigate the bond between GFRP reinforcement and concrete using inverted half-beam specimen. The inverted half-beam specimen were designed to simulate the conditions likely to be found in a bridge deck (no transverse reinforcement and small concrete cover). Products from two different manufacturers were chosen for the study because o f the widely varying characteristics o f the product. One manufacturer produced reinforcement with surface deformations created by a helical wrap o f glass fibers around the GFRP bar; the other manufacturer developed a ceramic coating that emulated the surface texture o f a deformed steel bar. The two different bar types exhibited different bond behaviors. The bond for the bars with the ceramic deformations relied most heavily on mechanical interlock, as was evident from cracking patterns. The bond for the bars with the helical wrap deformations relied most heavily on friction. Both bar types demonstrated large variability for the bond specimen that failed in bar fracture, with some bar failure loads more than two standard deviations below the average bar tensile strength.