STUDIES IN FLEXURAL BOND STRENGTH OF CONCRETE REINFORCED WITH TENSION STEEL

Abstract

For concrete and steel to work together in a beam it is necessary that stresses to be transmitted between the two materials. The term bond is used to describe the means by which the slip between concrete and steel is prevented or minimized. Wherever the tensile or compressive stresses in a bar change, bond stresses must act along the surface of the bar to produce the change. Bond stresses are in effect longitudinal shearing stresses acting on the surface between the steel and concrete. Bond strength between reinforcing steel bar and concrete depends upon the properties of materials (Concrete and Steel) and the interaction at the face of two materials. Thus, compressive strength and shrinkage of concrete are important and influencing properties of concrete. Tensile strength and surface properties (surface area an-d- ribs ci-idracicrisics) utcG1" "tar an -1.-...4.77....,;rig-prepcz-tizz tcr:;..ing bet:veer. steel bars and concrete. Ribs characteristics of steel bars influence the interlocking strength component of the total bond strength. In the present study, attempts have been made to study the growth of bonding force with different overlapping length of 8, 10, and 12 mm TMT rebar embedded in the concrete beams. It has been also tried to know the factors which mostly influence the bond strength. An attempt has been made to compare provisions of IS 456:2000, BS 8110:1985 and ACI 316:1999. The concrete has mix proportion of 1:2.04:3.33 with the water cement ratio of 0.47 at cement content of 400 kg/m3. Concrete cubes and cylinders have been tested to know the strength of concrete and to ascertain the ratio of cylinder to cube strength. A number of beams with varying overlapping length and diameter have been tested under four point loading system. The testing has been so designed as to keep the influence of self weight of beam less. Test results have been presented and certain inferences have been arrived on the basis of relevant discussion.