Logo
Search
Close this search box.

Expansion Joints

REPLACEMENT OF EXPANSION JOINTS ON EXISTING BRIDGES
IMPORTANT LINKS
METHODOLOGY FOR INSTALLATION OF EXPANSION JOINTS
  1. The most important aspect of the expansion joint is how properly it is leveled and embedded in good quality concrete by experienced/staff workers.
  2. In case of existing bridge blockout cavity will be prepared by chiseling/pneumatic hand held concrete breakers. Jack hammers will not be used. The existing reinforcement of deck slab must not be damaged but to be cleaned, straightened and preserved.
  3. The blockout cavity should be brushed cleaned.
  4. For bondage between the old and new concrete, apply bonding agent Sikadur-32 LP or (equivalent) to the existing exposed edges of the concrete.
  5. For high early strength of concrete, use water reducing agent Sikament-163 (600 ml / cement bag) along with hardener accelerator as Sikarapid-1(750 ml / bag) or equivalent.
  6. Low cost admixtures containing chlorides and sulphates shall not be used.
  7. Concreting on sun heated steel plates / shuttering beyond 32° c will not be allowed.
  8. A3 concrete (280 kg / cm² and grade 60 steel will be used.
  9. While using admixtures manufacturers specifications must be followed.
  10. Complete wet curing for 7days is must, otherwise prefer using concrete curing compound Anticsol-E15 (0.20 kg / m) or equivalent within 6 hours of concreting and cover the concrete area with opaque / colored plastic sheets.
  11. When the bridge is located over a River / Canal / Nullah, sealing of joint using backup rod and Sikaflex-Pro 3WS filler is not required and let the water flow down to the nullah underneath.
  12. But in case of overhead bridges, following additional treatment is required for sealing of joint.
    • After the installation and curing of the joint, clean the joint gap with wire brush and remove the dust with a blower.
    • Fix the backup rod of specified dimension at a depth of 25 mm from the top.
    • Apply Sikaprimer-3 (or equivalent) with paint brush.
    • Apply oil resistant resins Sikaflex-Pro 3WS (or equivalent) in the upper 25mm cavity in a concave shape, over filling of compound should be avoided.
  13. Indigenous expansion joint is not a propriety item. It can be copied and the joint can be manufactured and placed by any contractor
  14. Steel strips 25×60 thickness 3mm at 500 c/c, welded to top and bottom of vertical plates, have been added to maintain spacing of vertical plates during the construction of the joint, don’t forget to remove temporary steel strips within three days of concreting of joints.
  15. Preferably the expansion joint should be manufactured in 2m length or less than 2m and assembled at the site.
  16. The joint is composed of two steel plates welded to anchors in 3 layers. These joints are manufactured in segments of 2 meters length and prepared in a shop/factory and then carried to the site. For quality sake manufacturing of these joints at the bridge sites is prohibited.
Rehabilitation Schemes

In order to economize the cost of joint repairs, following three rehabilitation schemes have been developed for economy in construction cost.

    • Rehabilitation Scheme I. Where the joint is fully damaged and it needs a complete replacement. Here we have to see which segment or length of the particular joint needs replacement. In most cases the joint is not damaged for its entire length of 10 meters which is the full width of the deck. In case a particular joint is damaged for its quarter or half length, then only that particular joint length should be replaced. All joints are manufactured and supplied in segments of 2-meters length. For example; where a joint is damaged for a length of 4 meters out of its total length of 10 meters, then only 2 segments of 2 meters each are required to be replaced. The cost of replacement of full expansion joint is as per meter length (NSI-I).
    • Rehabilitation Scheme II. In certain cases, the condition of the joints itself is in good condition, but the Concrete Dam which is outer concrete on its both sides is deteriorated. In such cases, there is no need to replace the joint completely, rather the concrete on its both sides of the joint should be excavated and replaced using fresh concrete with the specified additional quantity of steel. This scheme also includes cleaning of gap between the steel plates from debris and removal of temporary steel strips, if any. The cost of such rehabilitation work will be as per meter length (NSI-II).
    • Rehabilitation Scheme III. At time it is observed that the Concrete Dam on one side of the joint is only damaged which needs replacement. This scheme also includes cleaning of gap between the steel plates from debris and removal of temporary steel strips, if any. The cost of this type of work will be as per meter length (NSI-III).

For new bridges
In case of new construction, first the deck concrete will be placed leaving a cavity for the expansion joint by filling sand in the cavity area. After all the deck slabs and approach slabs have been concreted, the expansion joint will be placed as per drawings and with additional reinforcement as specified. Asphaltic surfacing will be done last.

First AWC then expansion joints (special instruction)

  1. In all cases the AWC should be placed first leaving the cavities for the expansion joints which will be installed last after the AWC has been placed and compacted properly. The top levels of expansion joints and concrete dams should be in level with the top of AWC.
  2. At the end don’t forget to remove the temporary steel strips welded to steel plates of the expansion joints

Steps:

  1. Asphaltic wearing course should be completed before installation of expansion joint. Also manufacture steel joints in pieces having length not more than 2m each piece and existing cavity to be filled with sand.
  2. Remove sand from the existing cavity.
  3. Place expansion joint and additional reinforcement as specified.
  4. Apply form work such that top of expansion joint and the AWC are absolutely leveled.
  5. Apply old to new concrete bonding agent to existing / exposed concrete surfaces fill the cavity using Class D1 (5000psi=350 kg/cm²) concrete. And start wet curing within 18 hours of concreting.
  6. Remove all temporary form work including steel strips welded to steel plates.

Notes:-

  1. Concreting of expansion joint will be done after completion of AWC, so that the top level of concrete is in level with top of AWC.
  2. Use Grade 60 steel for additional reinforcement and Class D1 (5000psi = 350kg/cm²) concrete.
  3. In case temporary strips are welded to steel plates. Then these strips must be removed after concreting of the joint.
  4. Use of jack hammers for breaking of concrete is not allowed. Instead use hand held pneumatic concrete breakers.

The Drawings/Methodology to Replace Damaged Expansion Joints is as follows:

Replacement of Expansion Joints
Logo

Welcome to Highway Bridges, where cutting-edge technology meets timeless craftsmanship in bridge construction. Explore how we’re shaping the future of infrastructure with sustainable solutions.

Facebook-f Twitter Youtube Linkedin-in
Quick Links
Important Links

© 2024 – CECON | Highway Bridges, All rights reserved