Bond Slip Performance of FRP Bars in Fiber Reinforced Lightweight Concrete

Abstract

Increasing environmental concerns, economic crises and depletion of natural aggregates have evoked the use of materials that are cost effective, durable and possess enough strength. Lightweight Concrete (LWC) has the advantage of using light weight aggregate instead of the natural coarse aggregate which help preserve natural resources, reduce construction cost, and protect environment. Compared to Normal Weight Concrete, Lightweight Concrete is likely to have higher brittleness and lower mechanical properties. Therefore, improving this aspect of lightweight concrete has the key focus of researchers. Countless number of studies had been conducted by incorporating chopped fibers which can enhance the intrinsic deficiencies of concrete like poor ductility, high brittleness and low tensile strength. Different synthetic fibers such as polypropylene fibers, glass fibers etc. can help to counter such deficiencies. Therefore, Bond slip performance of LWC is especially important to ascertain the behavior of structures since it is a perilous issue in the design of reinforced concrete structures. So, this study focuses on investigating bond slip performance of Lightweight structural concrete incorporating synthetic fibers like Polypropylene and Glass Fibers. A total of 120 pullout specimens were casted and tested as per ASTM D7913 and ACI 440.3R-11. Three types of bars, deformed steel rebar, GFRP rebar and BFRP rebar, were embedded in standard cylinders to check their bond slip performance. Also, three parameters were discussed in this study, Bar diameter, bar type and Concrete Type. Results indicate that with the increase in bar diameter bond strength decreases for all types of rebars. Furthermore, the BFRP exhibited higher bond strength followed by steel rebar and GFRP rebar having the lowest bond strength among these three. It was also investigated that the strength of concrete has no effect on bond strength of FRP bars. Finally, the experimental data were compared with different prediction models from researchers and different standards. It was concluded that CEB-FIP Model 2010, CSA S6 19, JSCE and Wambeke and Shield prediction models produced results that are fairly comparable vi with the experimental data. However, due to significant errors, therefore it is essential to develop equations that can accurately predict the bond slip behavior of light weight structural fiber reinforced concrete.