Evaluation of Various Temperature Levels on the Reliability Index for Reinforced Concrete Members Made of Geopolymer Mixes Subjected to Chloride Concentration

Abstract

Chloride-induced corrosion is a major durability concern for reinforced-concrete bridge decks exposed to de-icing salts, and increasing temperature may accelerate chloride transport. This study evaluated the probability of chloride-induced corrosion initiation and the reliability index of bridge decks made with two geopolymer concrete mixes containing 50% fly ash and 50% slag, and 40% fly ash and 60% slag. Maximum temperatures from 25°C to 45°C were considered under low- and high-emission climate scenarios. Chloride diffusion coefficients were corrected for temperature and incorporated into a probabilistic performance function. Monte Carlo simulation with 100,000 iterations was applied to concrete-cover depths of 40 mm and 50 mm with coefficients of variation of 20%, 25%, and 30% at exposure periods of 50 and 100 years. The results showed that increasing maximum temperature increased the probability of corrosion initiation and reduced the reliability index. At 45°C, the 40% fly ash–60% slag mix with a 40 mm cover and a 20% coefficient of variation produced probabilities of 13% and 35% at 50 and 100 years, respectively; the corresponding values for a 50 mm cover were 2% and 9%. For the 50% fly ash–50% slag mix with a 40 mm cover, the probabilities were 27% and 50%. Polynomial relationships described the reliability index as a function of maximum temperature. Overall, a 50 mm concrete cover and the 40% fly ash–60% slag mix provided comparatively improved resistance to chloride-induced corrosion initiation.