Abstract:
Numerous techniques have been used for the rehabilitation of existing RC structures.
Concrete or steel jacketing, fiber-reinforced polymer wrapping are commonly available
techniques. To improve the response of bridge piers, fundamental approach employed
in experimental investigations, is the confinement of concrete. Various techniques
improve the strength and durability but few drawbacks, such as increase in weight of
structures in concrete jacketing, fire resistance and debonding are a few drawbacks.
Cementitious composites having compressive strength greater than 17 ksi, lie in the
category of Ultra High-Performance Concrete. UHPC is a composite cementitious
material with superior mechanical properties as compared to normal strength
concrete. High packing density, low water cement ratio, high binder ratio, addition of
high range water reducing admixtures and steel fibers results in increase in
compressive strength by 3-5 times as that of ordinary Normal Strength Concrete. This
study was carried out to investigate the response of Ultra High-Performance Concrete
using Normal Strength Concrete as a substrate under varied loading conditions to
simulate the actual forces on bridge piers, namely slant shear, bi surface shear and
split tensile. Variation in substrate surface treatment (As cast, drill holes and grooves),
inclusion of micro steel fibers and their effect on elevated temperatures was also
studied. The experiments showed that the strength of bond decreases with the
elevation in temperature. Drill hole technique exhibited the highest bond strength in bi
surface shear. Whereas inclusion of steel fibers in UHPC resulted in increase in
strength of bond due the bridging effect created between overlay and substrate.
