Proceedings of the International rilem conference Materials, Systems and Structures in Civil Engineering 2016

77

International RILEM Conference on Materials, Systems and Structures in Civil Engineering 

Conference segment on Service Life of Cement-Based Materials and Structures 

22-24 August 2016, Technical University of Denmark, Lyngby, Denmark 

 

the cast-in-place piers and bearing platforms, using both stainless bars in first reinforcement 

layer and surface silane impregnation, have quite high reliability index,  >5.0; the 

prefabricated piers adopt epoxy-coated bars in first reinforcement layer and surface saline 

impregnation, achieving  =2.32 at 120 years. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 2: Failure probability of concrete elements in HZM project through Monte-Carlo 

simulation for bridge elements in splashing and tidal zones. 

 

The bridge elements in immerged zone also have satisfactory durability safety margin: the 

cast-in-place platforms use stainless bars and surface silane impregnation and the failure 

probability is very low; the prefabricated platforms use epoxy-coated steel bars instead thus 

have a reliability index  =2.81 at 120 years; the bored hole piles achieve  =2.42 at 120 years 

without special protection. For prefabricated tunnel segments, the reliability index is 

evaluated respectively as  =2.81 (interior) and  =2.13 (exterior) at 120 years. 

 

 

5.  Preliminary maintenance planning 

 

A preventive maintenance strategy is adopted, intervening in the deterioration of concrete 

elements in early stage. The basic maintenance planning considers mainly two aspects: the 

durability performance level of elements denoted by failure probability pf or reliability index 

SL

 at 120 years, and the structural importance of elements. The maintenance techniques 

consist in performing the surface chloride extraction by electrochemical method and applying 

silane impregnation on the surface of elements periodically. The maintenance period is 

recommended to be 20-40 years: the intervention period 20 years is recommended for the 

elements without stainless steel bars and the period of 40 years is attributed to the elements 

using stainless bars due to their much lower failure probability (<10

-6

). For tunnel segments, a 

cathodic protection system has been installed to protect the steel bars against the unexpected 

durability failure. The activation time is preliminarily set as 100 years, corresponding to the 

failure probability p

f

=1%. It should be noted that this basic maintenance scheme is to interact 

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78

International RILEM Conference on Materials, Systems and Structures in Civil Engineering 

Conference segment on Service Life of Cement-Based Materials and Structures 

22-24 August 2016, Technical University of Denmark, Lyngby, Denmark 

 

with the durability inspection/ monitoring data and the real-time durability assessment during 

the service life. 

 

 

6. Summary 

 

This paper introduces the HZM sea link project in construction, covering the durability design, 

quality control, durability assessment in construction and the maintenance planning of 

concrete structures in the project. The durability design establishes firstly a general 

philosophy and divides the requirements onto material and structural levels, and then employs 

model-based methods to determine the quantitative design parameters for durability. On the 

basis of the quantitative requirements, the quality control is performed with concrete 

compressive strength and chloride diffusivity as control parameters. The on-site data were 

collected for the chloride diffusivity and concrete cover thickness. Using these data, the 

statistical properties for variables in chloride ingress model are updated, and a comprehensive 

durability assessment is given through a full probabilistic method. The assessment shows that 

the durability safety margin is satisfactory, with 

SL

>2.0 at 120 years. A preventive 

maintenance planning is recommended for the RC elements. 

 

 

References 

 

[1]  HZMBA, Bidding Documents for General Contracting of Design and Construction of 

HZM Project Main Works in Artificial Islands and Tunnel, Hong Kong-Zhuhai-Macau 

Bridge Administration, Zhuhai, China (2010). 

[2] ISO, General principles on the design of structure for durability (ISO13823:2008(E)), 

International Organization for Standardization, Genève, Switzerland (2008). 

[3] Li, K.F., Chen, Z.Y. and Lian, H.Z., Concepts and requirements of durability design for 

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