Probability-Based Durability Design for Concrete Structure with Crack: Bimodal Distribution of Chloride Diffusion

Abstract

* (Received March 3, 2015 / Revised March 24, 2015 / Accepted March 25, 2015)Chloride ions in RC (Reinforced Concrete) structures can cause very severe corrosion in reinforcement steel. It is generally in formed that chloride penetration can be considerably accelerated by enlarged chloride diffusion due to cracks. These cracks play a rol e in main routes through which chloride ions penetrate into the concrete, and also lead to steel corrosion in RC structures exposed to ch loride attack, such as port and ocean structures. In this paper, field survey including evaluation of crack and chloride concentration distribution in concrete is performed to investigate an effect of crack on chloride diffusion. The service life of cracked conc rete exposed to the marine environmental condition is estimated considering the crack effect on chloride diffusion. For this purpose , diffusion coefficients in cracked concrete are obtained based on the field survey. Using the relationship between diffusion coe fficientsin the cracked concrete and the crack widths, service life of the cracked concrete is predicted in a probabilistic framework. A bimodal distribution with two peaks, consisting of a weighted sum of two normal distributions is introduced to describe chloride diffus ion of the concrete wharf with crack. Keywords : Chloride diffusion, Crack width, Service life, Probability, Bimodal distribution* Corresponding author E-mail: jjuni98@hannam.ac.kr