Fracture behavior of pervious concretes: The effects of pore structure and fibers

The fracture response of pervious concrete specimens proportioned for different porosities, as a function of the pore structure features and fiber volume fraction, is studied. Stereological and morphological methods are used to extract the relevant pore structure features of pervious concretes from planar images. A two-parameter fracture model is used to obtain the mode I stress intensity factor (fracture toughness) and the critical crack tip opening displacement of notched beams under three-point bending. The experimental results show that the fracture toughness is primarily dependent on the porosity of pervious concretes. For a similar porosity, an increase in pore size results in a reduction in fracture toughness. At similar pore sizes, the effect of fibers on the post-peak response is more prominent in mixtures with a higher porosity, as shown by the residual load capacity, stress-crack extension relationships, and resistance curves. These effects are explained using the mean free spacing of pores and pore-to-pore tortuosity in these systems. A sensitivity analysis is employed to quantify the influence of material design parameters on fracture toughness.