Paper Title
Experimental Study on Bond Behavior of Reinforcing Bars in Plain and Fiber Reinforced Concrete

There is a need to re-evaluate the design requirements in the codes of practice such as crack widths and spacing, deflection, rotation capacity, anchorage and splice length, to propose new test procedures and assessment criteria for bond strength of bars incorporating various influencing parameters and with modified surface characteristics. The bond behaviour between concrete and steel bars is characterised by the development of tensile cracks when the chemical adhesion is lost as a result of mechanical interlocking. When FRC is used an improvement of the bond behaviour is observed as the presence of fibrescounteracts the crack openings.In the present investigation bondstrength and bond behaviour of the 150 mm cube specimens were studied by varying their matrix characteristics,barcharacteristics and confinement.Rebars of three different diameters 16,20 and 25 mm were used.Concreteof compressive strength M20 and M30 were used.Matrix confinement was varied by confining it with mildsteel and by 1% addition of steel strength varied between 19.50 MPa and 7.32 MPa for different variables.It was found that Bond strength increases with increasing compresive strength and age of concrete ,decreases with increase in diameter of the rebar. Bondstrength of the specimen confined with mildsteel helix was more than those with 1% added steel fibers.Addition of steel fibers did not contribute to the strength but improved the post cracking behaviour of the specimens.slip increased with decrease in bond strength. Slip varied between .45 mm for bond strength of 19.50 MPa and 2.3 mm for bond strength 7.32 MPa. keywords- bondstrength,compressive strength,diameter,pullout test,slip,steelfiber