Proceedings of the International Workshop on Seawater Sea-sand Concrete (SSC) Structures Reinforced with FRP Composites

Coastal cities like Hong Kong rely heavily on their marine/coastal infrastructure (e.g. ports, bridges & artificial islands) for social-economic development. A major challenge for marine infrastructure is its deterioration due mainly to steel corrosion in steel-reinforced concrete structures. 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. The use of fibre-reinforced polymer (FRP) to replace steel in concrete structures to eliminate the steel corrosion problem has been gaining increasing acceptance over the past two decades. If FRP is used as the reinforcing material, then locally available seawater and sea-sand can be directly used to make concrete instead of freshwater and river sand as FRP is expected to be little affected by the rich chloride content in seawater/sea-sand. The resulting structures, made of FRP and seawater sea-sand concrete (SSC) (i.e., FRP-SSC structures), have the potential to offer many significant advantages, including: cost-effective marine infrastructure with a longer service life, savings in material transportation costs, better protection of rivers due to reduced sand mining, and savings in freshwater which is a scarce resource on the planet. The idea of using SSC with FRP in marine construction was first proposed by the Chair of the present Workshop at a national conference in 2011 held in Hangzhou, China and later promoted internationally on a number of occasions. As a result, a significant number of research projects have since been funded around the world, and a number of publications have appeared on the subject. It is obvious that for this important technology to become widely used in the near future, extensive research is needed to gain an in-depth understanding of and develop design and construction methods for FRP-SSC structures. One key issue to be addressed is the long-term performance of FRP-SSC structures in marine environments. While significant evidence has accumulated that the rich chloride content in seawater/sea-sand has little effect on the performance of FRP composites, they can suffer deterioration due to other factors such as the ingress of moisture. This Workshop was organised to provide the first international forum for in-depth exchanges on FRP-SSC structures and closely related topics (e.g., behaviour of SSC; field exposure tests of FRP bars in marine environments) to achieve the following specific objectives: (1) Examine in detail the advantages and challenges brought about by FRP-SSC structures; (2) Provide a survey of research projects being undertaken or planned around the world on FRP-SSC structures and closely related topics; (3) Identify key issues to be tackled before FRP-SSC structures can be widely accepted in practice; and (4) Explore opportunities for international collaboration to accelerate research progress in the area. The program of the Workshop included 15 invited presentations on FRP-SSC structures or related topics. Each paper was followed by extensive discussions to achieve the objectives of the Workshop. The Workshop was attended by over 70 participants (including the invited speakers). Many people have contributed to the organization of the Workshop. We would like to thank all invited speakers for sharing their work and insight at the Workshop and all participants for their interest and support for the Workshop and their participation in the discussions. We are also grateful to the two co-sponsors (SEACON, a project funded by Infravation, and Fibrpro International Limited) for their support to the Workshop and to Prof. Tony Nanni for his help and enthusiasm for the Workshop. Over the past few years, we have benefited greatly from exchanges with many researchers on the topic, particularly through the preparation of a research proposal for submission to the Theme-based Research Scheme of the Hong Kong Research Grants Council. We are grateful to all of them for sharing their wisdom and insight with us. Our special thanks go to Dr. Guang-Ming CHEN and Ms Jan LIEN, who provided the much needed secretarial support, covering technical, logistics and all other necessary aspects.