Modeling carbonation depth of recycled aggregate concrete containing chlorinated salts

Abstract

The durability of recycled concrete is susceptible to degradation from both chloride salt attack and carbonation when exposed in service environment. The depth of carbonation in recycled concrete subject to chloride salt attack was studied here. This investigation assessed the effects of mineral admixture, replacement rate of recycled coarse aggregate, and quality of recycled coarse aggregate on the carbonation depth. The carbonation depth Recycled concrete was studied through accelerated simulated carbonation in the laboratory for 7d, 14d and 28d. Based on the results, the correlation analysis was conducted to investigate the relationship between depth of carbonation, mineral admixture, recycled coarse aggregate replacement rate, recycled coarse aggregate quality and the presence of chloride ions. The objective of this study was mainly to investigate the effect of internal chloride ions on the depth of carbonation of recycled concrete subjected to chloride salt attack. The study referred to previous academic research on carbonation in recycled concrete that had not been affected by chloride salts, and conducted a comparative analysis to identify the carbonation depth pattern in recycled concrete influenced by chloride salt exposure. The study discovered a negative correlation between the replacement rate of mineral admixture and recycled coarse aggregate and the carbonation resistance of concrete. Moreover, enhancing the quality of recycled coarse aggregate positively impacted the carbonation resistance of concrete. An improved model was developed that considers the effect of internal chloride salts on the carbonation depth of recycled concrete, in reference to the empirical prediction model presently available. The model demonstrated a high level of agreement with experimental outcomes, displaying an error range of between −4.32% and 8.27%. It enables an in-depth comprehension of the carbonation behavior of recycled aggregate concrete in an environment exposed to chloride salt attack. Based on the model, the service life of recycled concrete structures can be more accurately forecasted, which can provide a theoretical direction for enhancing the durability of engineering structure.