A multi-factor prediction model for chloride concentration in the interface zone of precast and cast-in-place concrete incorporating interfacial amplification and stress effects

To reasonably predict the chloride concentration in the interface zone of existing precast and cast-in-place concrete structures, this study establishes quantitative relationships between interfacial chloride concentration and governing factors, based on the rational Taylor model. The functional form and distribution characteristics of the Taylor model, together with its capability for multi-factor analysis, are well suited to the experimental data in this study. By introducing a multi-factor-dependent interface relative amplification coefficient, a multi-factor prediction model for chloride concentration in the interface zone is developed. Furthermore, the influence of sustained compressive stress on chloride transport in the interface zone is analyzed, and a prediction method applicable to existing precast and cast-in-place concrete structures under constant compressive stress is proposed. The proposed model can effectively predict the chloride concentration in the interface zone of existing precast and cast-in-place concrete structures. The model prediction accuracy of coefficient of determination ( R ² ) reaches 0.93 under unstress conditions, while the overall prediction accuracy for all data achieves an R ² value of 0.89. In addition, compared with existing methods, the proposed model significantly reduces the dependence on internal structural parameter acquisition while maintaining high prediction accuracy. The results of this study provide a fundamental modeling framework for durability assessment of strengthened precast and cast-in-place concrete structures in coastal regions, precast segmental bridges, and prefabricated concrete structures.