Investigation of crack propagation in Macro-synthetic Fiber reinforced concrete

The Structural Polypropylene fibre reinforced concrete (SPFRC) contains randomly distributed short discrete Polypropylene fibres which act as internal reinforcement so as to enhance the properties of the cementitious composite (concrete). The principal reason for incorporating short discrete fibres into a cement matrix is to increase the flexural tensile strength and increase the toughness and ductility and effect on properties of the fresh concrete and fracture properties of the resultant composite. These properties of SPFRC primarily depend upon length and volume of fibres used in the concrete mixture.\ud To determine these properties experimental work was carried out. For the study, Structural polypropylene fibres of two different lengths (lf) of 48 mm and 60 mm with dosage 3kg/m3, 4kg/m3 and 6kg/m3 (0.33%, 0.44% and 0.66% by volume) volume fractions (Vf) were used. The research reported in this study includes an experimental investigation to characterize selected mechanical properties of SPFRC and to study the effect of volume fraction of SPF and length of SPF on the mechanical properties.\ud To determine properties of concrete specimens (cubes and beams) were casted to determine the mechanical behavior such as compressive strength, flexural tensile strength. Test results showed that Structural polypropylene fiber enhanced the compressive strength and increase the toughness insignificantly. The failure of plain concrete specimens was sudden (brittle) for the flexural test. However, the concrete reinforced with Structural Polypropylene fibers showed more ductile behavior compared to the plain concrete. And also provide an interpretation for the observed tension response of fiber reinforced concrete in flexure in terms of crack propagation and toughening mechanisms in the composite