EXPERIMENTAL STUDY ON BEHAVIOR OF TERNARY BLENDED CRIMPED STEEL FIBER REINFORCED CONCRETE BEAM IN SHEAR

Concrete is most widely used construction material because of ease of construction and its properties like compressive strength and its durability. It is difficult to point out other material of construction which is versatile as concrete. This is well known that plain concrete is very good in resisting compressive strength but possesses less specific modu lus, low ductility and very little resistance to cracking. Internal micro cracks inherently present in the concrete and its poor tensile strength is due to propagation of such micro cracks eventually leading to brittle failure of concrete. Several admixtures have been developed to improve the strength and workability properties of concrete. Of all admixtures used in concrete, Micro Silica occupies a special position for quite a some reasons. The improvement of the durability, resistance to sulphate, freezing and thawing, alkali silica reaction, frost attack, increase in the compressive strength, reduces the permeability and bleeding. Micro Silica effectively improve the structure of interface eliminates the weakness of the interfacial zone. In the pa st, attempt has been made to improve tensile strength of concrete. This was achieved by the addition of small closely spaced and randomly oriented fibers, dispersed uniformly in the matrix. The fibers acts as crack arrestor and substantially improves in st atic and dynamic properties. Shear strength of steel reinforced concrete beams has been the subject of many controversies and debates since the beginning of 20th century. The shear strength of reinforced concrete beams has been extensively studied over the last five decades. A large number of experimental and analytical works have been carried out for the case of slender beams (having a shear span to depth ratio a/d > 2.0) with and without shear reinforcement under two - point loading. Transversely loaded r einforced concrete beams may fail in shear before attaining their full flexural strengths if they are not adequately designed for shear. Unlike flexural failures, shear failures are very sudden and unexpected, and sometimes violent and catastrophic. A thor ough knowledge of the different modes of shear failures and the mechanisms involved is necessary to prevent them. The present experiment is carried out to investigate the compressive and shear strength of ternary blended steel fiber reinforced concrete with 6% of micro silica and 15% of fly ash by weight of cement as partial replacement of cement and addition of different percentages like 0%, 0.5%, 0.75%, 1% and 1.25% of crimped steel fibers with aspect ratio of 80. Compressive strength of concrete is m easured by testing standard cubes (150mmx150mmx150mm) at the age of 7 and 28 days, Shear strength of concrete is measured by testing beams (1400mmx100mmx150mm) at the age of 28 days. Micro Silica and Fly Ash along with Steel Fiber in concrete has shown co nsiderable improvement in the compressive and shear strength of concrete. From the test results it is observed that concrete mixture with 6% Micro Silica and 15% Fly ash replacement of cement has shown the maximum compressive strength of 41.8MPa at 28 days . Concrete mixture with 6% Micro Silica and 15% Fly ash replacement of cement along with 1% crimped steel fiber has shown significant improvement in various properties at the age of 28 days indicated by 12% increase in compressive strength and 24% increase in shear strength. Hence ternary blended crimped steel fiber reinforced concrete with 6% micro silica and 15% fly ash is a novel material having superior performance characteristics compared with conventional concrete