Bond performance between deformed bars and concrete containing iron tailing sand exposed to high temperature

Abstract

Preparing green concrete with industrial waste and construction waste can save natural resources and protect the environment. Therefore, it is necessary to study the bonding performance of green reinforced concrete and its post-fire bonding performance. A total of 45 specimens were prepared, including ordinary reinforced concrete (RC0-S), reinforced concrete with iron tailing sand (RC0-IT), and recycled reinforced concrete with iron tailing sand (RC50-IT). A central pull-out test was conducted on specimens with a rebar diameter of 16 mm and a bond length of 80 mm exposed to 20 °C, 100 °C, 300 °C, 500 °C, and 700 °C, and the failure phenomena, bond stress-slip curve, and ultimate bond strength of three reinforced concrete specimens were compared. The test results show that: (1) The ultimate bonding stress and residual bonding stress of the three reinforced concretes all increase first and then decrease with elevated temperature. (2) When exposed to 100 °C, the bonding properties of the three kinds of reinforced concrete all reached the best. (3) When exposed to the same temperature, the reinforced concrete with iron tailing sand (RC0-IT) has the best high-temperature resistance among the three reinforced concretes. Furthermore, the formulas for calculating the bond strength are proposed, the bond stress-relative slip (τ-s) constitutive model is established, and the predicted results of the model are in good agreement with the experimental results. This study helps to accurately obtain the bond stress of reinforced concrete exposed to high temperatures.