Effect of Temperature on Bond Strength of Reinforced Concrete Structure

Abstract

The study has been carried out to investigate the influence of temperature on bond behavior of reinforced concrete. The effects of casting temperature and curing temperature on various properties of concrete were investigated. Four different temperatures (20 oC, 30 oC, 45 oC and 60 oC) were maintained for this purpose. Locally available materials were used to prepare the specimens. To observe the effect of coating on bond stress, three different types of coating were used in this work such as red oxide, synthetic enamel paint and aluminum oxide. The study also investigates the temperature effect on corrosion of reinforced concrete. In this work, pullout test and electrochemical corrosion were performed as a major test program. To carry out these tests, 100 mm dia and 200 mm high cylindrical concretes were prepared. A 12 mm dia MS bar was placed vertically at the center concrete layer. Bond stress measurement under different temperatures and coatings were the major findings of this work. Test results explained that volume of void increased with the increment of temperature. Result of bond strength showed 20% better performance for lower casting and curing temperature compared to higher temperature. Application of coating on rebar surface did not give satisfactory result of bond stress compared to non-coated rebar. 20 oC temperature induced specimens increase the time of corrosion crack initiation and decrease the penetration rate than 60oC temperature induced specimens. Coatings significantly showed a good agreements for corrosion effect on reinforced concrete. Among three coatings, aluminum oxide revealed better performance against pullout test and electrochemical corrosion test. Finally, it can be concluded that temperature at 20 oC gives significant bond stress and provides better protection for corrosion than 60 oC temperature.