Case Study on LCC of Concrete Structures Considering Probability Distributions of Deterioration and Re-Deterioration Rates

Abstract

The deterioration process of concrete structure usually possesses large uncertainty. Furthermore, the re-deterioration process after the repair suffers much greater uncertainty, resulting in a difficulty in verifying cost-benefit of repair. This study calculates LCC of RC structures that have deteriorated by chloride attack by simulating their deterioration and re-deterioration processes with a consideration on probability. Here, a patch repair and a cathodic protection were dealt with as repair methods to be investigated, and LCC with these repair methods were calculated by assuming their average expected lifetimes and their dispersions based on the results of investigations for the concrete structures. In carrying out the calculation, the effects of deterioration rate and water-cement ratio were also investigated. From this, the following results were obtained: Both the average and the standard deviation of the LCC of patching repair were larger than those of cathodic protection. In all the cases examined here, the LCC of pathing repair was five times as large as that of cathodic protection. While the deterioration rate by chloride attack largely affected the average of LCC, it less affected the standard deviation of LCC. The increase of water cement ratio raised the average of LCC. The influences of water cement ratio on the re-deterioration should be investigated in future. If the average and dispersion of the lifetimes can be determined based on the investigation on the structures, they may affect the LCC of the patch repair and the cathodic protection.