Bond characteristics of corroded pullout specimens exposed to elevated temperatures. (June 2020) - Tariq, Faraz
Abstract: This paper presents an experimental study carried out to examine the extent of deterioration of bond properties of super ductile (SD) TMT reinforcing steel bars with normal strength concrete on account of exposure to multiple combinations of corrosion-induced damage in terms of mass loss and exposure to elevated temperatures. The study involved an experimental evaluation of bond properties and behavior of corroded pullout specimens exposed to elevated temperatures. RILEM specified Pullout specimens with centrally placed rebars of various sizes were exposed to impressed current accelerated corrosion to achieve desired levels of corrosion in terms of percent mass loss of (2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, and 18%, etc.). and then to temperatures targeted at (200 °C, 400 °C, 500 °C, 600 °C, 700 °C & 800 °C). The corroded and subsequently heated pull out bond specimens were tested to failure in pull-out mode using displacement controlled UTM to investigate the residual bond strength and bond-slip behavior. The slip of the rebar, at the loaded as well as the unloaded end, was recorded through a set of linear variable displacement transducers (LVDT) arrangement mounted to the projected reinforcing bar on each side of the specimen. The study presents unique bond-slip response curves depicting the overall behavior of the bond mechanism. The results indicate a notable reduction in bond strength as well as the bond-slip response of pullout specimens on account of the superimposition of the two phenomena. A detailed account of the test results, analysis and discussion has been presented. The findings of this study have direct implications on procedures used for predicting the ultimate behavior of aged or corroded structural elements exposed to an accidental fire. A trend of deteriorations has been established for all research variables and a model best fitting the experimental data has been proposed in terms of a regression correlation.