Test Method for Cracking Resistance of Cover Concrete due to Corrosion of Reinforcement

Abstract

Expansion of the rust volume produced from corrosion creates the radial pressure pressing the cylindrical wall around reinforcing bars. To simulate this radial pressure from the expanding rust, a new experiment method is introduced. By this method, the mechanical device has to be embedded in each specimen during casting concrete. This device transfers the applied force and the displacement from vertical axis to the pressure and the displacement in radial direction. Therefore, the radial pressure and the displacement pressing the cylindrical wall around the reinforcing bars can be determined from the applied force and the displacement in the vertical direction. Two mortar specimens with different covering thickness, 50 and 90mm, were tested in order to examine the behaviors of the crack in the thinnest cover direction. The experimental results from this new experiment method are shown and compared with the calculated results of elastic, elastic-partially cracked, and fully plastic theory. In comparison, the experimental results of radial pressure were found to be higher than the elastic and the elastic-partially cracked but lower than the plastic theory. Furthermore, it was found that both normalized forms of the ultimate radial pressure and the ultimate radial displacement have linear relationships with non-dimensional cover thickness.

Simulation for Corrosion Cracking of Cover Concrete in Reinforced Concrete Structures

“…The ultimate internal pressure P ultimate in equation (18) was simply estimated by elastic and fully plastic models 36) . Meanwhile, in more advanced analysis, P ultimate was estimated by taking into account the tensile-softening behavior of concrete 35) .…”

“…However, the average value of threshold chloride, which was equal to 1.8kg/m 3 , was selected and used in this study. Similarly, the cracking time of cover concrete will be obtained if the accumulative corroded mass of reinforcing steel exceeds the limit corroded mass m lim , based on Piyamahant and Shima 35) .…”