FRP Stay-in-Place Formwork for Floor and Deck Construction


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Title: FRP Stay-in-Place Formwork for Floor and Deck Construction

Author(s): M. Oliva, H. Bae, L. Bank, and J. Russell

Publication: Special Publication

Volume: 257


Appears on pages(s): 109-132

Keywords: bridge decks; concrete decks; crack control; fiber-reinforced composites; formwork; fiber-reinforced polymer (FRP); FRP planks; pultruding; stay-in-place form

Date: 10/1/2008

The evolution of a new application for the use of fiber-reinforced polymer (FRP) formwork is described from its inception, through research and to actual implementation in a construction project. FRP formwork is becoming an attractive alternative to traditional wood forms in concrete floor construction and particularly for highway bridge decks. The recent development of new wide flange or bulb tee precast concrete bridge girders has resulted in short spans between girder flanges that need to be filled by formwork before the deck can be cast. FRP planks are an ideal solution for spanning this short gap and may be left as stay-in-place (SIP) forms. A commercial pultruded FRP floor plank was adopted for use as SIP forming for bridge decks. Rather than being used as intended, however, the plank is turned upside down before the concrete is placed and becomes bonded to the concrete. The testing of this SIP formwork system to prove its capacity in resisting static and impact loads during construction, its contribution to crack control in concrete under flexural loading, and its bond characteristics with a concrete deck are described. The results of the bond tests are used to create a "bond element" that could be used to predict the flexural behavior of concrete members with the FRP SIP formwork. A case study of construction of a highway bridge deck on U.S. Highway 12 with the new forming system is detailed after the FRP form capacities were proven through load testing. The advantages of using FRP planks for bridge deck construction are discussed and compared with traditional construction using wood forming that is subsequently removed.