ABSTRACT
This paper presents the results of a two stage experimental program that investigated the effectiveness of polymer fibres as shear reinforcement in reinforced concrete beams. The first stage focused mainly on beams with normal strength concrete, and the second stage focused on high strength concrete beams. The test variables examined include fibre type, fibre volume, shear-span to depth ratio and concrete strength. A total of forty seven beams were tested until failure under a simply supported symmetrical two point load system. This total included seven control beams with no fibres and no shear reinforcement, and two beams containing conventional shear reinforcement only. All beams had an overall depth of 250 mm and width of 150 mm, and were tested with shear-span to depth ratios of either 2.1 or 3.3. Three polymer fibre types were used in volume fractions of up to 2%. Significant ultimate shear strength increases were observed when polymer fibres were added. In many cases the shear strength increase achieved was greater than the increase observed in the control beams with conventional shear reinforcement. The overall conclusion is that although shear strength increases were noted in the normal and high strength concrete polymer fibre reinforced beams tested, the scatter of results made it difficult to ascertain a consistent trend. This in part was due to difficulties that were encountered in mixing and cast the concrete beams that contained significant volumes of fibres.
