Theme-Based Research Scheme Project
The project aims to address the severe deterioration problem of marine infrastructure caused by steel corrosion by replacing steel with fibre-reinforced polymer (FRP) as the reinforcing material. This replacement then will allow the direct use of seawater and sea-sand in making the concrete (i.e., seawater-sea-sand concrete or SSC). As a result, marine infrastructure will enjoy a much longer life span, while energy consumption and environmental pollution will be reduced in the construction process.
The project is led by Prof. Jin-Guang Teng of the Department of Civil and Environmental Engineering (CEE), The Hong Kong Polytechnic University, and has been awarded a grant of around HK$47.2 million from the Research Grants Council (RGC) through the Eighth Round of its Theme-based Research Scheme (2018/19). In addition to the funding from the RGC, the local participating universities of the project provides around HK$5.2 million as matching funding, bringing the total budget of the project to around HK$52.4 million.
The scope of the research project includes the development of innovative steel-free structural forms as well as new methods for the design, construction and performance monitoring of FRP-SSC structures. A key scientific challenge for the project is the establishment of a multi-scale, multi-physics approach for predicting the long-term performance of FRP-SSC structures in a marine environment over a service life of more than 50 or even 100 years.
Prof. Jin-Guang Teng is the Project Coordinator and Principal Investigator of the project. Co-Principal Investigators of the project include: Prof. Christopher K.Y. Leung from the Hong Kong University of Science and Technology; Prof. Zong-Jin Li from the University of Macau; Prof. Yi-Qing Ni and Prof. Chi-sun Poon from PolyU; Prof. Florence Sanchez from Vanderbilt University; Prof. Tong Sun from City, University of London; Mr Sheng-Nian Wang from the CCCC Fourth Harbour Engineering Institute Co. Ltd.; and Prof. Li-Min Zhou from PolyU. The project will take five years to complete (i.e. by December 2023).
The project will take five years to complete (i.e. by December 2023).
Coastal cities like Hong Kong rely heavily on their coastal and marine (referred to as “marine” hereafter for brevity) infrastructure (e.g., ports, bridges, artificial islands and offshore wind farms) for social-economic development. A major challenge for marine infrastructure is steel corrosion, which is the main cause for infrastructure deterioration. Typically, steel corrosion costs an economy around 3% of its GDP (3% of Hong Kong’s GDP in 2016 = US$9.6 billion). The American Society of Civil Engineers (ASCE) estimated in 2013 that US$3.6 trillion would be needed from 2013 to 2020 to maintain a state of good repair for the US infrastructure. Another major challenge for marine infrastructure is the shortage of fresh water and river sand (or crushed stone fines) for making concrete. Apart from the negative environmental effects of consuming great amounts of fresh water and river sand/crushed stone fines, their transportation is both expensive and environmentally detrimental; desalination of seawater and sea sand is also costly.
This project aims to address both challenges by developing a new type of concrete structures to achieve sustainable marine infrastructure: seawater sea-sand concrete (SSC) structures reinforced with fibre-reinforced polymer (FRP) composites (e.g., FRP bars and tubes) (referred to as FRP-SSC structures). As FRP composites have excellent corrosion resistance and are highly durable, they are gaining increasing acceptance as replacement of steel in conventional reinforced concrete structures in aggressive environments (e.g., bridge decks exposed to dicing salt). By capitalising on the durability of FRP composites, seawater and sea sand can be directly used in constructing marine infrastructure. FRP-SSC structures will revolutionise the construction of marine infrastructure.
For FRP-SSC structures to be widely used, extensive research is needed to gain an in-depth understanding and develop design and construction methods. Although FRP composites do not corrode, they do deteriorate, although only slowly, in aggressive environments. The key scientific challenge for the project is to understand and predict the life-cycle behaviour of these structures and to develop a life-cycle design methodology. While past research on material/structural performance deterioration has relied primarily on the direct empirical extrapolation of accelerated laboratory test results to real-time performance, this traditional approach has been increasingly questioned as being highly uncertain/unreliable. In the proposed project, a new approach based on multi-scale multi-physics modelling of material and structural deterioration will be established and verified with rigorous experimentation to predict the life-cycle performance of FRP-SSC structures.