Today, concrete is one of the most widely used construction materials. Concrete enjoys several advantages over wood and steel and other construction materials such as flexibility in shaping, fire resistance, durability and ease of production and finally cheaper and more economical. But along with these advantages, there are also disadvantages such as heavy weight , low tensile strength and brittle behavior . Research result have indicated that the ductility of concrete using fiber can be greatly increased. Additionally, an overall improvement in application of fiber is increase in tensile flexural and shear strength. Concrete cracking can be delayed and controlled with application of fibers in concrete. Compressive strength of concrete is increased by adding some kind of fibers to concrete mixtures. This study investigates the application of a new type of polypropylene fiber called Barchip (HPP fibers) in concrete lining of water pressure tunnels experimentally. In this paper, a comparison between the behavior of steel fiber reinforced concrete and HPP fiber reinforced concrete with ordinary concrete is made. Advantages and disadvantages of Barchip fibers used for concrete lining of water tunnels are presented. Alpha In this study, concrete mixtures with 0.4,0.6 and 0.8 volume percent of HPP fiber and steel fibers were provided. Changes in compressive strength, tensile strength, flexural strength, toughness and energy absorption, permeability of concrete and chloride penetration depth were measured relative to the control sample. All tests were undertaken according to ASTM and BS requirements. The obtained results showed that the Barchip fibers were not effective in compressive strength compare to steel fibers, but the effects of Barchip fibers i tensile strength, flexural strength, toughness and energy absorption were significant. Based on the results, the effects of Barchip fibers on concrete characteristics such as the toughness, concrete permeability and chloride penetration were higher than that of steel fibers. The results showed that with application of HPP fibers, durability and serviceability of the concrete linings could be remarkably extended. Key Words fiber reinforced concrete, polypropylene fiber, concrete lining, water tunnel, durability.
