Elastomers have excellent adhesion to concrete and are not suspectable to softening within normal range of ambient temperatures and normally Elastomers exhibit a higher degree of elongation of as much as 10 percent extension but in practice, this should be limited to 50 percent and groove depth to width ratio should be 1.2, material should be prevented from adhering to bottom so that crack remains free as a live crack.

Rehabilitation of structures may be required due to several reasons one reason is:
Environmental effects some common causes are constructional deficiency, environmental effects, deficiency in design, overloading of structures eir due to un anticipated loading or due to accidents and user made changes in structures during service life of structure.

The restoration of end block of girder was done by completely dismantling concrete in end block after distressing of cables and new reinforcement was welded with existing reinforcement of girder and new concrete with vertical joint was provided with extra care.

Segments of bridge super structure are cast at site in lengths of 10-30m in stationary forms located behind abutments and each unit is cast directly against previous unit and after concrete attains desired strength new unit is joined to previous unit by post tensioning and assembly of units is pushed forward in a step wise manner to permit casting of succeeding segments.

In many cases of heavily loaded, girders shear distress is observed near supports in form of diagonal tension cracks and shear cracks may arise due to improper detailing or compaction of concrete near support zone in such cases holes are drilled diagonally and rebars are placed and grouted to arrest shear cracks.

The form work for cat in situ construction is supported by steel frame work attached to completed part of bridge and formwork moves from one complete section to next part and sequential operations in this method are: fabrication of steel truss, placing of reinforcement, concreting using concrete mix, curing concrete, threading high tensile cables and anchoring and grouting of cables, releasing formwork.

The strengning of an existing structural element by increasing its load bearing capacity and altering load supporting system by changing spans by shifting or removing of supports, conversion of continuous beam to single span beam and vice versa etc.

Due to various reasons such as corrosion of reinforcements due to extreme exposure conditions, especially when un bonded tendons are used, high tensile strands may get damaged resulting in loss of prestresss in girder.

If spans are large, y can be sub divided by means of temporary piers to control magnitude of bending moments with in safe limits and according to Raina this construction technique has been applied to spans up to 60m without use of temporary false work bents and also spans up to 100m have been built using temporary supporting bents and main girders must have a constant depth generally varying from 1/12 to 1/16 of longest span.

The deck is made up of voided slabs 90-105cm thick and routine inspection indicated cracks in soffit of end and central sections and review of design calculations indicated deficient tensile reinforcements at certain locations of deck slabs, following two rehabilitation methods were examined: installation of prestressing elements and external reinforcement with bonded on steel plates.