METHODOLOGY FOR INSTALLATION OF ELASTOMERIC BEARING

 

INSTALLATION OF ELASTOMERIC BEARING

1. Scope:

  The work shall consist of fixing of elastomeric bridge bearings in position

as per details shown in drawings.

2. References:

 MoRT & H specifications clause no 2005 and Technical specifications of contract.

3. Equipments:

Auto level, levelling staff.

4. Tools:

   Measuring steel tape, line rope.

5. Responsibility:

·       Responsibility of Implementation of this procedure lies with Site engineer and incharge of structures.

·     Centerline marking responsibility lies with surveyor.

6. Materials:

     Elastomeric bearings, Fosroc conbextra GP2 or Equivalent material,

Fosroc Nitto bond –EP or equivalent material.

7. Procedure:

·    The location where the bridge bearing to be installed shall be swept            clean and made free from debris and other foreign matter which will            effect the adhesion of bearing to the surfaces.

·     The bridge bearing shall be kept in the recess made in concrete on the pier cap /pedestals.

·     The concrete surface where the bridge bearing will sit shall be free from local irregularities within r1mm tolerance in height.

·  Bridge bearings shall be placed in between true horizontal surface within a maximum tolerance of 0.2% perpendicular to the load and at true plan positions on their control line marked in receiving surface within r3mm.

 · An epoxy adhesive such as ^·FOSROC - Nitobond EP· or equivalent material will be uniformly applied to form a film of 2mm thick to the both surface of concrete and the face of the bridge bearing, which will be in contact with the each other.

·  After elapsing of 15-20minutes the bridge bearing will be pressed gently on the surface where adhesive is applied by keeping the glued surfaces opposite to each other.

·  To rectify the local irregularities and to make the concrete surface truly plane, in the recess of 5mm deep provided for bridge bearing to sit, the following method would be adopted. First the concrete surface will be swept clean to remove all the debris or dust by using wire brushes or water. A thin coat of epoxy adhesive will be applied on the dried concrete. After a lapse of 15-20minutes a non-shrink self-leveling cement grout such as ^„FOSROC – Conbextra GP2^· or Equivalent material will be poured to a maximum thickness of 2mm. This grout will be kept continuously moist for 3 days, before installation of bearing.

·  The exposed surface of the concrete shall be finished and kept moist for the first 24hours and cured further until attains sufficient strength as shown in drawings.

8. Safety Requirements:

·       Wherever the bearing Installation is under process bottom area shall be properly barricaded.

·       Any labour, if being used in the job for surveying shall be screened and trained.

·       All workmen at work area shall wear PPE^·s and reflective jackets, safety belts.

·       During night work sufficient lighting shall be provided.

·       Leveling staff shall be wooden or fiber.