Reliability-based efficiency considering CO2 emission owing to silane treatment on concrete structures under chloride attack

An approach to consider two principal aspects, i.e., (1) reliability-based service life extension of silane-treated concrete under chloride attack and (2) the cumulative amount of CO2 emission owing to treating by silanes, is here developed based on totally ten random variables. As such, this study collects the experimental data on two main effects of silane treatment; penetration depth of silanes (42 tests) and effective diffusion coefficient of silane-treated concrete (21 tests) for proposing descriptors for illustrations. Apparently, the distribution type of the penetration depth and the diffusion coefficient ratio is found as Beta function and lognormal, respectively. As a tool, the Latin Hypercube scheme is integrated with a two-layer material model developed within Crank-Nicolson based finite difference method. Such material model is aimed at capturing spatial diffusion coefficient owing to the existence of silane-treated and substate concrete. Considering different random application times, three silane treatment strategies are adopted. From the study, the diffusion of chlorides in silane-treated zone is delayed causing about 135% extension of expected critical time, that the chloride content at a threshold depth approaches to the critical value of reinforcement corrosion. Incorporating the target reliability index of 0.84 (80% confidence of no reinforcement corrosion), the reliability-based service life is extended owing to silane treatment by about 32%. For judging the best silane treatment strategy, this study defines a terminology called “reliability-based efficiency” in terms of the ratio of the reliability-based service life extension after silane treatment to the expected cumulative amount of CO2 emission at the end of service life. Considering a proper design of treating by silanes, the quality of concrete must be selected based upon incorporating a specific target reliability or failure probability such that the effect of silane treatment is properly active.