Abstract:The synthetic fibers, with three lengths of 4.7,5.6 and 6.5cm respectively and each dosage of them was 5 kg?m-3, were used for the preparation of grade C40 concrete. Weber consistency, compressive strength and the toughness of concrete samples, including square boards, circular plates, beams and coped beams, were tested to analyses the effect of synthetic fibers on the mechanical proportion of fiber reinforced concrete, comparing with that of concrete with the equal volume (40 kg?m-3) of steel fibers. The results indicated that the addition of synthetic fibers lead to both decreases of flowability and compressive strength, and reduced the bending strength of concrete beam, and the longer the length of synthetic fibers, the lower the compressive strength of concrete. The synthetic fibers affected little initial rupture strength of concrete square boards or circular plate. The synthetic fibers can enhance fracture energy of concrete obviously and this action is higher than the same volume content of steel fibers. The synthetic fiber with length of 5.6 cm impressed the most of fracture energy of concrete. The stress and the deflection curve of synthetic fiber reinforced concrete displayed a “platform” structure in the process of its decline. Although the platform height was less than that of the steel fiber reinforced concrete, its length was longer obviously. It is due to the material characteristics of the structure of synthetic fibers.
