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Development of pseudo-ductile permanent formwork with glass fiber reinforced plastics reinforcements

Authors Cao, Qian
Issue Date 2007
Summary This investigation focuses on an innovative design which can enhance the performance and durability of structural components. Pseudo-ductile cementitious composites (PDCC) is a group of fiber reinforced cementitious composites with excellent ductility and crack control capability, while glass fiber reinforced plastics (GFRP) reinforcements can be used as replacements for steel reinforcements to eliminate the corrosion problem. By the combined use of these materials strategically, improvement in structural performance can be achieved. Using pseudo-ductile cementitious composites (PDCC) of relatively low water/binder ratio, permanent formworks are first fabricated. Normal concrete is then cast to make structural components. With low permeability and very high crack resistance, the permanent formwork acts as a very effective surface cover to prevent the corrosion of steel reinforcements. The formwork can be made with PDCC alone, or with the incorporation of glass fiber reinforced plastics (GFRP) rods. In some structural components, the GFRP reinforcements will be sufficient to provide the necessary load-carrying capacity. In others, steel reinforcements can be added to produce a component with very high durability (as steel is well protected) as well as ductile behavior. In this research, the design of PDCC mix is first presented, followed by bending test results on beams made with PDCC formwork and normal concrete. Emphasis will be placed on the assurance of proper bonding between the formwork and the cast concrete. Then, PDCC formworks with embedded GFRP are fabricated. Concrete beams with GFRP/PDCC formwork are prepared with and without additional steel reinforcements. Based on the tests on these specimens, it is found that the formwork and the concrete behave as a composite system and interfacial debonding is the cause of failure in most cases. Nevertheless, for some of the specimens, the ultimate load approaches the calculated value for concrete crushing failure. Also, when both steel and GFRP reinforcements are present, good ductility can be achieved. Finally, issues related to durability and practical applications of PDCC formwork are studied. According to the result of the present investigation, the PDCC permanent formwork has a good potential for practical applications.
Note Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2007
Language English
Format Thesis
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