Potentially significant mechanical improvements in tension can be achieved by the incorporation of randomly distributed, short discrete fibers in concrete. The improvements due to the incorporation fibers significantly influence the composite stress - strain ($sigma$-$varepsilon$) characteristics. In general incorporating fibers in a plain concrete has relatively small effect on its precracking behavior. It, however, alters its post-cracking behavior quite significantly, resulting in greatly improved ductility, crack controls, and energy absorption capacity (or toughness). Therefore, a thorough understanding the complete tensile stress - strain ($sigma$-$varepsilon$) response of fiber reinforced concrete is necessary for proper analysis while using structural components made with fiber reinforced concrete. Direct tensile stress applied to a specimen is in principle the simplest configuration for determining the tensile response of concrete. However, problems associated with testing brittle materials in tension include (i) the problem related to gripping of the specimen and (ii) the problem of ensuring centric loading. Routinely, indirect tension tests for plain concrete, flexural and split-cylinder tests, have been used as simpler alternatives to direct uniaxial tension test. They are assumed to suitable for fiber reinforced concrete since typically such composites comprise 98% by volume of plain concrete. Clearly since the post-cracking characteristics are significantly influenced by the reinforcing parameters and interface characteristics, it would be fundamentally incorrect to use indirect tensile tests for determining the tensile properties of fiber reinforced concrete. The present investigation represents a systematic look at the failure and toughening mechanisms and macroscopic stress - strain ($sigma$-$varepsilon$) characteristics of fiber reinforced concrete in the uniaxial tension test. Results from an experimental parametric study involving used fiber quantity, type, and mechanical properties in the uniaxial tension test are presented and discussed.
