Experimental investigations on bond performance of GFRP bars

Abstract

Corrosion of steel is one of the major problems concerning construction field which becomes more severe when the structures are subjected to harsh environment which is harmful to structure as well as costs high for repair. Hence, deviating to alternate building materials is essential in upcoming years. One of the latest findings among them is replacement of steel with Glass Fiber Reinforced Polymer (GFRP) bars. Experimental and numerical studies on various strength parameters of these bars are being undertaken to examine their replacement to steel. This work contains experimental investigations on bond performance of Glass Fiber Reinforced Polymer (GFRP) bars. In the present study the bond behavior GFRP bars with and without wrapping of binding wire embedded in polypropylene fibers reinforced concrete and conventional steel rebar embedded in plain concrete was tested. The grade of concrete used for investigation was M40 and for bond testing 10, 12 mm diameter steel and GFRP bars were used in this experimental work. Pull-out test was conducted in Universal Testing Machine (UTM). It was observed that bond behavior of GFRP bar and concrete were lesser than steel bar by 41.06 % for 10 mm diameter bars and by 31.63 % for 12 mm diameter bars. Although it was observed that GFRP bar wrapped with binding wire possessed lesser bond stress than steel bars, it has improved bond stress compared to GFRP without wrapping by 16.06 % for 10 mm diameter bar and by 14.22 % for 12 mm diameter bars. Also maximum slippage was observed for GFRP than steel bar and GFRP with binding wire wrapping. GFRP bar slippage of 10 mm and 12 mm diameter is 130.88 % and 63.64 % and respectively higher than steel bars. The bond strength and maximum slippage of GFRP bar is found to be decreased with increase in diameter.