Experimental Determination of Double-K Fracture Parameter for Polypropylene Fibre Reinforced Concrete

Polypropylene fibre reinforced concrete is randomly distributed fibres abate the nucleation, growth of matrix cracks and bridge them after their creations. These reduce the brittleness and provide the strength gain, fracture toughness and ductility. The Double K fracture parameter can describe the cracking process of polypropylene fibre reinforced concrete well since go through three stages: the stage of crack arises, expand stage and break stage. Stress intensity factor caused by bridging stress and the net stress intensity factor were given based on the hypothesis of linear asymptotic superposition. Polypropylene fibre reinforced concrete is short and randomly distributed fibres abate the nucleation and growth of matrix cracks and bridge them after their creations. These reduce the brittleness and provide the strength gain, fracture toughness and ductility. A fibre as reinforcement can be effective in arresting cracks at both micro and macro levels. The effect of varying fibre percentage on initial cracking load, ultimate failure load, initial fracture toughness KICini., unstable fracture toughness KICun. and cohesive fracture toughness KICC is repeated and studied. Variation in fracture toughness and brittleness index is studied. Closed loop servo controlled equipment has been used in the present work to evaluate optimum Polypropylene fibre percentage for getting maximum fracture toughness is also suggested.