Investigation of Effective Factors on the Performance of Grooving Method to Prevent Debonding of FRP Sheets from Concrete Surface

A major challenges in flexural strengthening of reinforced concrete beams by FRP laminates is FRP sheet debonding from the concrete substrate, which leads to the premature failure of strengthened structural member. Surface preparation of concrete before FRP sheets installation is a suitable method to postpone debonding, however the effectiveness of the method is limited by the problems such as practical costs and environmental pollution. Grooving is an innovative technique to overcome debonding of FRP laminates from concrete surface, which has been recently used in Isfahan University of Technology (IUT). In this paper, the effect of some factors influencing the grooving capability aiming at reducing the debonding potential of FRP sheets from the concrete surface is addressed. These factors include the width and the depth of the grooves. In the experimental study, thirty-three prism specimens of dimensions 100×100×500 mm were subjected to 4-point flexural loading. The surfaces of the specimens have been grooved. After reinforcing the specimens by CFRP sheets, the four point flexural tests were carried out to measure the ultimate loading capacity. The results indicate that debonding can be completely prevented or highly limited by applying specified width and depth for the grooves.