THE ROLE OF CONCRETE FOR BRIDGES AND FLY OVERS

The role of concrete in bridges has been undergoing exotic transformation over the last hundred years. The first recorded use of concrete for bridges relates to the last decades of the Nineteenth century. Since then there has been consistent upgradation in the use of concrete as bridge construction material, both qualitatively and quantitatively. From the humble volume – proportioned concrete with compressive strength of around 12 MPa, concrete of up to 120 MPa is now being used. Environmental concerns have resulted in ecofriendly green concrete. Other developments include a spectrum of concretes high performance concrete, extra-high strength concrete, self-compacting concrete, fibre reinforced concrete, reactive powder concrete, lightweight concrete, smart concrete etc. The use of Colloidal concrete (COLCRETE), though not a new practice is sometimes the best alternative as in the case of Second Hooghly bridge in Kolkata, India. The use of such a spectrum of materials in bridge design and construction has reflected in realization of bridges of longer spans, greater durability, lighter weight and has tremendously increased the speed of construction. The paper also deals with the advances made in precast construction especially precast pretentioned beams and the ease in construction and economy achieved by its use for bridge superstructure.

• INTRODUCTION

• DURABILITY REQUIREMENTS OF CONCRETE

• SEISMIC EFFECT ON BRIDGES

• MINIMUM CEMENT CONTENT

• PRETENSIONED BEAMS AND PRECAST CONSTRUCTION

• IMPACT OF CONSTRUCTION EQUIPMENT

• VARIOUS TYPES OF CONCRETE FOR BRIDGES AND FLYOVER

• EPILOGUE

• ACKNOWLEDGEMENT

• REFERENCES