Macro polypropylene fiber influences on crack geometry and water permeability of concrete

Abstract

In order to study the effect of macro polypropylene fiber on crack geometry (tortuosity, surface roughness) and water permeability of concrete, the independently designed laser scanner was adopted to obtain the surface coordinates of the crack, the coefficients of crack tortuosity and surface roughness were introduced and the crack tortuosity and surface roughness were evaluated quantitatively through the MATLAB programming, the crack geometry of the specimens reinforced with macro polypropylene fibers and specimens without any reinforcement were compared. A self-designed device was adopted to the water permeability test, the influence of macro polypropylene fibers on water permeability of cracked concrete was studied. The Poiseuille law was modified regarding to the tortuosity factor and surface roughness factor. The results showed that: the coefficients of variation of the tortuosity factor and surface roughness factor were relatively small for all kinds of samples and could be used to verify the crack geometry of concrete. The crack geometry of the concrete was affected by the macro polypropylene fiber and the tortuosity and surface roughness of the crack increased with the increasing of fiber dosage. The modified Poiseuille law could be adopted to predict the water permeability of the cracked concrete.