1. INTRODUCTION
1.1 Reinforced Concrete
Reinforced concrete is the most commonly used material in construction industry.
There is no other material, which is utilized by human being in such large quantities
world wide as the concrete. The world consumption of concrete was over 3 billion
tones in 1990. The concrete, produced by mixing of cement, aggregate and water, has
the unique characteristics of withstanding weather and exposure conditions, high
strength and affordable cost. Uptill recent past, concrete was thought to be maintenance
free material until failures of the structures were reported from various parts of the
world. Some of the notable examples are the poor durability performance of bridge
decks in USA and Europe, and the deterioration of reinforced concrete structures in the
coastal regions of Arabian Gulf. The factors attributed to the failures include severe
environmental conditions, poor construction practices and improper choice of materials.
It is estimated that in 1989, $ 20 billions were needed for the rehabilitation of highway
structures in USA and more than 600 million pounds sterling in the UK [Maslehuddin
et al., 1990].