, Volume 8, Issue 1, pp 35-41

The effect of initial rust on the bond strength of reinforcement

Abstract

An experimental investigation on the relationship between corrosion of reinforcement and bond strength in pull-out test specimen has been conducted to establish the allowable limit of rust of reinforcement in the construction field. The reinforcing bars used in this study were rusted before embedded in pull-out test specimen. The first component of this experiment is to make reinforcing bar rust electrically based on Faraday's theory to be 2, 4, 6, 8 and 10% of reinforcing bar weight. For estimation of the amount of rust by weight, Clarke's solution and shot blasting were adopted and compared. Parameters also include 24 and 45 MPa of concrete compressive strengths and diameter of reinforcing bar (16, 19 and 25 mm). Pull-out tests were carried out according to KSF 2441 and ASTM C234 to investigate the effect of the degree of rust on bond strength. It is found from the test results that the test techniques for corrosion of bar used in this study is relatively effective and correct. Results show that up to 2% of rust increases the bond strength regardless of concrete strength and diameter of reinforcing bar like the existing data. It might result from the roughness due to rust. As expected, the bond strength increases as compressive strength of concrete increases and the diameter of bar decreases.