Quantitative analysis of macro steel fiber influence on crack geometry and water permeability of concrete

In this work, the water permeability of the cracked concrete has been investigated. Three types of cylindrical specimens with different fiber content were pre-cracked by the feedback controlled splitting test, and the specimens without any fiber reinforcement were also studied as reference. The water permeability of the specimens with different crack width was measured by hydraulic permeability test. The coordinate data of the crack surface was collected by the self designed data acquisition system, the total crack length and surface area of the samples were analyzed, the crack geometry (tortuosity and roughness) was evaluated quantitatively. A modified factor ξ was introduced to the Poiseuille law to verify the permeability of the cracked specimen. The results showed that with the addition of macro steel fibers, the deformability of the specimens was improved significantly and the crack width could be controlled. The coefficient of the water permeability of the specimens was declined by fiber addition, the modified Poiseuille law could be used to evaluate the water permeability of the cracked concrete, the modified factor ξ decreased with the increasing of fiber dosage. The crack tortuosity and surface roughness increased obviously with the addition of steel fiber.