Effects of nylon fiber and nylon fiber fabric on the permeability of cracked concrete

Abstract

This study discusses the permeability of fiber-reinforced concrete (FRC) with cracks and investigates the feasibility of waste fiber fabrics for concrete reinforcement from the perspective of environmental protection and economic benefits. Compressive strength, splitting tensile properties, and permeability of nylon fiber-reinforced concrete (NFRC) were compared with those of recycled nylon fiber fabric-reinforced concrete (NFFRC). Plain concrete (PC) was also studied as reference. A self-made device was adopted for the variable water pressure permeability test, and the influence of different kinds of fiber (NF, NFF) on the permeability of cracked concrete was analyzed. Results showed that the fiber has little influence on the compressive and splitting tensile strength of concrete, but the FRC showed considerable toughness after cracking. Fibers incorporated into concrete can change the geometry of crack and the permeability of cracked concrete decreases with the increase of fiber dosage. The crack permeability and the correlation coefficient R2 of fitting line gradually decrease with the increase of hydraulic pressure. The modified Cubic law can accurately predict the water flow behavior and permeability in small cracks (0–300 μm) of NFRC or NFFRC under the hydraulic pressure no more than 0.1 MPa, but this prediction becomes inexact with the increase of hydraulic pressure in this test.