Bond Characteristics of FRP Composite with Concrete Substrate

Abstract

Many existing structures nowadays are unable to give their services effectively. Due to various reasons, they get deteriorated or get damaged much before the time for which they are designed for. The evaluation of the damage can be measured by various destructive and non destructive tests. Such damaged structures need to be retrofitted. Various structures like bridges, dams, for which rehabilitation is very difficult, in such cases retrofitting can be used as an effective measure. There are various methods for retrofitting like jacketing, shear wall, infill wall etc apart from the conventional methods. Out of all these methods jacketing using fibre composites are getting popularity these days. These FRP composites mostly fail in debonding. Since delamination is a very brittle and sudden failure mechanism without prior to yielding, it must be avoided in practical applications. This nature of the Stress level in interfacial bond between the FRP sheet and the concrete substrate is therefore important to study. In the present study the research was carried to study the effect of CFRP bond with the concrete substrate. In this study the sheet was pulled from the concrete surface and the slip was measured. The idea behind this test was to find the stress level which leads to its debonding and relate the stresses with those generated at flexural testing. The parameters studied were the different surface preparation. The samples were tested on controlled/undamaged beam and damaged beam. Apart from this grooved and holed samples were also tested. The results of the samples were finally compared to the existing models and previous research. From the results it was found that by cutting longitudinal grooves and filling them with an appropriate epoxy was an effective substitute for surface preparation, and can cause a great increase in ultimate load of beams compared to those without any surface preparation. The shear failure of concrete was noticed in case of damaged beams. The holed sample did not show appreciable results. The results of the controlled/undamaged beam were compared with the previous researches and were found to be in satisfactory ranges.