23-09-2014, 01:51 PM
Abstracts: Concrete is a mixture of cement (usually Portland cement) and stone aggregate .When mixed with a small amount of water, the cement hydrates lock the aggregate into its rigid structure. Typical concrete mixes have high resistances to compressive stresses however, any appreciable tension (e.g. due to bending) will break the microscopic rigid lattice resulting in cracking and separation of the concrete. For this reason, typical non reinforced concrete must be well supported to prevent development of tension. Concrete possesses very low tensile strength, limited ductility and little resistance to cracking. Internal micro cracks are inherently present in concrete and its poor tensile strength is due to the propagation of such micro cracks eventually leading to brittle fracture of the concrete. Nowadays, fibers are used as a reinforcing material in place of steel in concrete. These fibers could prevent cracking and substantially improve the tensile strength, impact strength wear and tear, fatigue resistance and ductility of concrete. Since concrete is weak in tension hence measures must be adopted to overcome this deficiency. Hence fibers of different material can be utilized in the making of concrete which provide adequate tensile strength.