EFFECT OF CONFINEMENT ON PLAIN AND FIBRE REINFORCED HSC

Abstract

The objective of the present investigation is to experimentally establish the similarities or differences in behaviour of plain and fibre reinforced high strength confined concrete under uniaxial compression. In this investigation, confinement using ferrocement encasement has been considered for axially loaded short circular columns. When columns are confined using circular or square ties, the sections midway between the ties are ineffectively confined and also there is spalling of cover. However, in ferrocement the cover is only a few millimeters thick, the ratio of core area to the cover area is generally large, and so spalling of cover is delayed. The mesh wires are also closely spaced and there are several layers of mesh. Hence concrete is effectively confined. Thus confinement by ferrocement can offer certain advantages over confinement by ties, hoops and spiral reinforcement. The experimental programme consisted of casting of 72 cylindrical specimens of size 150 x 300 mm. These include both plain and fibre reinforced confined specimens of three grades of concrete. The quantity of confinement is varied by using no layer, single layer and double layers of wire mesh in the specimens. Besides, cubes of size 150 mm were also cast for determination of strength. All specimens were tested at 28 days of age under uniaxial compression and load - deformation curves were obtained using data aquisation systems (DAS) machine. The scope and objective of this thesis is to study the effect of confinement on stress-strain curves, strength, ductility and toughness due to variations in grade of concrete, quantity of confinement and addition of fibres.