Durability for concrete structures in marine environments of HZM project: Design, assessment and beyond

This paper reviews the fundamentals of the durability of structural concrete, and then applies the concepts to the durability design, quality control, performance assessment and maintenance planning of concrete structures in Hong Kong-Zhuhai-Macau (HZM) sea link project with design working life of 120 years. The durability design adopts a multi-level philosophy for different durability risks and uses model-based approach to determine design parameters. The long-term exposure data of 30 years were used to calibrate the chloride ingress model and quantify the modelling uncertainty. The durability quality control was realized through converting the design values to laboratory characterization values, especially for the chloride diffusivity. With the data collected in construction phase, a full-probabilistic assessment is performed on the achieved performance against the chloride ingress, serving as basis for maintenance planning. The open issues related to the durability of concrete infrastructures with long service life are elaborated in the end.