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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. • This study aims to investigate the impact of chloride salts on carbonation in recycled aggregate concrete. • The influence of recycled aggregate on carbonation of recycled aggregate concrete has been studied. • The carbonation depth of recycled concrete is reduced due to the presence of chloride ions. • An empirical prediction carbonation model of recycled aggregate concrete with embedded chloride ions has been developed. [ABSTRACT FROM AUTHOR]

• Treated and non-treated SNS flakes enhanced the mechanical and fracture properties of the cementitious composites. • The SNS strengthening and toughening mechanisms in the cementitious composites are crack bridging and crack deflection. • The SNS induced performance enhancement similar to that of graphene-based materials. This paper examines the mechanical and fracture properties of cementitious composites doped with a new type of 2D bio-nanoplatelets sheets, synthesized from sugar beet pulp waste. The sugar beetroot nanosheets (SNS) were added to the cement pastes at different concentrations. The influence of SNS treatment and water-to-cement (w/c) ratio on the performance of the cementitious composites was elucidated. The experimental results showed that 0.2- wt% and 0.35 were the optimal SNS concentration and w/c ratio for increasing the compressive, splitting tensile and flexural strength, flexural modulus, fracture energy and fracture toughness. These properties were enhanced by as much as 12.15%, 36.87%, 39.91%, 32.69%, 69.01% and 49.06%, respectively. This enhancement was due to crack deflection and crack bridging mechanisms in the cementitious composites as a result of the high specific surface area of SNS and the strong chemical and physical bonding of SNS with the hydration phases. The SNS materials offers strong advantages over graphene-based materials on improving the engineering properties of cementitious materials and reducing their cost and CO 2 emissions. [ABSTRACT FROM AUTHOR]