Based on the whole life cycle theory, the research stage of an expressway bridge is divided into six stages: preliminary preparation design stage, production and processing stage of bridge structural materials, transportation stage of materials, on-site construction stage, operation stage and waste recycling stage, and the calculation model of expressway bridge carbon footprint is constructed. Two bridges along the Pingxiang Expressway in Jiangxi Province were chosen as case studies. Their carbon emissions across the entire life cycle were computed using the bill of quantities. Findings indicate that the material production stage accounts for the highest proportion of carbon emissions throughout the life cycle, whereas the construction stage registers the lowest proportion. Lastly, the results are compared with existing research to validate the feasibility and accuracy of the calculation model.

The durability of structure cannot be guaranteed when a corrosion expansion crack reaches the surface of the reinforced concrete member. In this paper, firstly, based on the existing theoretical model of steel corrosion degree, the calculation process of the model and the determination of the relevant parameters in the model were analyzed and discussed. Secondly, the stiffness reduction factor of concrete in the model was calculated according to the existing experimental data, and the engineering formula of the steel corrosion degree was established, which was related to the surface crack width of reinforced concrete. Moreover, the experiments of steel bar corrosion were carried out with different components of surface crack width, in which the parameters of the bar diameter, concrete protection layer thickness, and water‐cement ratio were taken into consideration. The experimental phenomena and results were further analyzed and discussed. Finally, comparing with the experimental data, the engineering formula presented in the paper was validated. The results show that the calculated values by the engineering formula are in better agreement with the experimental values than those by the existing model, which provide a theoretical basis for further study on the durability limit state of the structure.

The diffusion of Sulfate ions in concrete is a complex process and affects the performance of concrete. Experiments on the time-dependent distribution of sulfate ions in concrete under the coupling of pressure load, dry-wet circulation, and sulfate attack, and the diffusion coefficient of sulfate ions with various parameters was tested. The applicability of the cellular automata (CA) theory to simulate the diffusion of sulfate ions was discussed. In this paper, a multiparameter cellular automata (MPCA) model was developed to simulate the impacts of load, immersion ways, and sulfate solution concentration for the diffusion of sulfate ions in concrete. The MPCA model was compared with experimental data, considering compressive stress, sulfate solution concentration, and other parameters. The numerical simulations verify the calculation results based on the MPCA model are in good agreement with the test data. Finally, the applicability of the established MPCA model was also discussed.