A model specification for fiber reinforced non-participating permanent formwork panels for concrete bridge deck construction

This paper discusses the development of a model design and construction specification for thin [less than 38 mm (1.5 in.)] non-participating permanent formwork panels (also known as, stay-in-place forms and lost forms) made of FRP or FRC materials with or without non-metallic reinforcements for use in the construction of concrete slabs, in particular, highway bridge decks. The use of such forms is motivated by the narrow gaps [less than 1 m (39.4 in.)] that are often found between the flanges of wide flange “bulb-T” prestressed girders that are becoming commonplace in the US highway construction industry. Bridge contractors have expressed an interest in using non-participating permanent forms to reduce the time and cost required in forming and stripping the plywood forms for such narrow gaps. A model specification that was developed to enable engineers to design and specify such forms is provided in the appendix to this paper. To develop the specification, different permanent formwork panels were fabricated and tested. These included (1) flat cementitious panels reinforced with short glass or polypropylene fibers, (2) flat cementitious panels reinforced with bi-directional FRP thin grids, (3) flat cementitious panels reinforced with unidirectional FRP reinforcing bars, and (4) off-the-shelf, commercially manufactured pultruded FRP thin-walled, ribbed planks. The specification provides guidance for the width of gaps permissible for each Class of system and details of prescriptive and performance tests that must be performed to qualify the products for use in construction.