Effect of nylon fiber aspect ratio on the mechanical properties of fiber reinforced concrete

Abstract

Nylon fiber reinforced concrete is to mitigate the cracking trend of concrete due to the temperature and relative humidity of environment. Being a synthetic material nylon offers high tensile strength and good chemical resistance to the composite. Due to the benefits, the use of FRC has steadily increased during the last two decades. In Bangladesh nylon fiber is locally available and also cheaper than the other fibers like steel fibers and glass fibers. The properties of fiber volume, aspect ratio and orientation of the nylon fiber are responsible for efficient transfer of stress between matrix and the fiber. In this study the effect of the aspect ratio and the volumetric ratio of the nylon fiber on the mechanical properties of concrete has been explored. Three different fiber lengths (19mm, 25mm and 50mm) of same diameter (1/14 mm) were used to analyze the influence of aspect ratio on the properties of concrete composite. The principal mechanical properties of concrete mixes were tested in the laboratory to identify the effects of the selected length of fiber. The results of compressive strength test, splitting tensile strength testand flexural strength test indicated improvement of the mix over non fibrous concrete. Aspect ratio 266 (19 mm length and 1/14 mm diameter) exhibits the maximum compressive strength (89%) over the non-fiber-concrete mix. Accordingly, the tensile strength showed higher value for low aspect ratio. Moreover flexural strength test indicates that increase in the fiber length results in the significant increment in the flexural capacity. The higher the aspect ratio the higher ductility can be achieved, which may affect the design of a structural member. Nylon fiber cannot replace the reinforcing structural steel but the results showed that the fiber can be a worthy strength provider with a certain aspect ratio and volume percentage. As this material is available in the local market of Bangladesh and also the use of it in the concrete will act ecologically, this study is exploring the different aspects of nylon fiber reinforced concrete.