Maintenance of Bridges:
The maintenance of bridges, including remedial measures, shall be framed based on the detailed inspection report, including an in-depth analysis of causes for defects, deficiencies, construction faults or other probable effects.
- After finalizing the Bridge maintenance criteria, the maintenance team will prepare the necessary drawing for maintenance work and submit these to the higher authority for approval.
- The maintenance team or specialized agency shall execute the job after getting approval from the concerned department.
Also, Read: Blowholes/Surface voids/Bugholes in Concrete Surface
Priorities of Maintenance:
Based on the condition assessment report, every defect shall be categorized depending on the priorities of maintenance or attention required.
- Urgent Maintenance: Jobs marked as Urgent priority shall be attended to urgently as this may affect the full component of the structure/system as well as the project.
- Special Maintenance: That maintenance of bridges shall be taken as special attention next order of priority for which required detailed investigation and findings.
- Recurrent Maintenance: Next to special in order of priority where the defects which occur recurrently. Recurring work is periodic maintenance work like overlaying, painting, replacing etc.
- Routine Maintenance: Defects attended routinely under the above priority category exaggerate the life of structures and maintain the whole project.
Also, Read: Elastomeric Bridge Bearing – Advantages & Limitations
Bridge Maintenance Planning and Procedure:
To finalize the maintenance of bridges, the concerned Engineer or team will study the defects/distress in details recorded during the inspection, assess the reason for defects, check structural adequacy if any, check construction fault if any, suitable maintenance scheme etc. In general, IRC- SP 37:1991 guidelines shall be followed for the bridge’s load-carrying capacity. The detailed procedures of the bridge maintenance scheme are as follows.
- Study and Summarize the defects/ distress recorded during the inspection.
- The cause of defects should be identified.
- Prepare the priority list of the defects.
- Check the structural adequacy, if any, after studying the design calculation.
- Consultation should be taken with the experienced designer/agency if required.
- Check construction inadequacy, if any.
- Finalize a suitable maintenance scheme or consultant’s recommendation.
- Working drawings or sketches should be prepared for maintenance work.
- Environmental Health and Safety plans should be available.
- The authorities should approve the working methodology.
- Prepare a traffic diversion plan or blockade if required.
- Prepare a comprehensive Maintenance Report.
Also, Read: Causes, Prevention and Repair of Concrete Surface Defects
Maintenance of Bridges Criteria and Necessary Action:
On approval of the bridge maintenance scheme, the maintenance of bridges shall be executed by the maintenance team or specialized agency appointed through tender.
Maintenance for Waterway Structure:
- Abnormal scour:
- Recording the pattern of scouring and finding the cause of such scour.
- Any formation of the island to be removed.
- Inform higher authority immediately of the remedial measure.
- Obstruction in the waterway:
- Obstruction to be removed completely.
- Erosion of bank, pitching:
- Repair of pitching is essential.
- New/extra pitching, if required to be provided during the maintenance.
Also, Read: Rusting of Iron Rebar in Concrete – Special Repairing
Maintenance of Bridges Foundation and Substructure:
- Settlement of foundation:
- Record the settlement and compare it with the tolerance limit.
- Check design adequacy for excess settlement.
- Strengthening of the existing foundation is required, if possible.
- Scour at pier location:
- Record the pattern of scouring and find out the cause of such scour.
- Formation of the island to be removed.
- Inform higher authority for future course of action.
- The crack needs immediate attention to prevent further damage and deterioration of the existing structure.
- Cementitious/epoxy-based grouting by the nozzle can be allowed.
- Damage due to the impact of vessels:
- Damages can be repaired with the help of cementitious grouting by the nozzle.
- Spalling of concrete:
- Chipping of local surface and removing all the loose material.
- Replacement with high-strength cementitious grouting.
- It can be repaired with micro-concrete/epoxy mortar/polymer mortar depending upon the severity of the damage.
- The surface is to be repaired by plastering.
Also, Read: Nondestructive Testing of Concrete – Methods & Guidelines
- Porous Surface/Honeycomb:
- Surface to be cleaned, and find out the cause of leakage.
- Epoxy-based cement grouting may be allowed by the nozzle.
- The surface to be repaired by plastering etc.
- Exposed reinforcement and rust staining:
- Chipping of local surface and removing loose material.
- Application of zinc-based epoxy paint can be permitted after cleaning of reinforcement.
- If required, additional reinforcement is to be provided by welding to make up the steel area.
- High-strength cementitious grouting may be allowed to repair the affected area.
- Surface to be repaired by plastering etc.
- Wet spots and Vegetation growth:
- Wet surface to be cleaned, and find out the cause of leakage.
- Close the leakage by epoxy-based cement grouting by nozzle or laying of waterproofing layers etc.
- Surface to be repaired by cement mortar etc.
- Record the movement within the tolerance limit, and check design adequacy for excess movement.
Also, Read: Environment Health and Safety(EHS)
Maintenance of Bridges Superstructure:
- Deflection< L/350:
- Routine check-up of riding comfort for any unusual deflection and check condition is becoming worst, recommend load test if required.
- Deflection> L/350:
- Strengthening by providing additional members if required.
- Epoxy-based grouting by the nozzle.
- Cracks, Spalling of the concrete and Honeycomb:
- Same as mentioned in the maintenance of bridges scheme for the foundation.
- Joints between segments:
- For minor defects, it is to be repaired by grouting etc.
- Structural adequacy to be checked for major defects.
- Consult with the specialized agency if required.
- As per approved methodology, if required, strengthening of external prestressing, high strength cementitious grouting, etc.
- Prestressing steel:
- Defect in HDPC pipes: To be repaired by Tedlar tape.
- Voids in the grout and corrosion protection in strands to be vacuum grouted are recommended by a specialized agency.
- Excessive corrosion, loss, damage, etc., to be replaced as per the recommendation of a specialized agency.
- Grout cap, Slip, distortion, Cracks in concrete, cracks in anchorage and corrosion to be repaired, painted, grouted or replaced as per the recommendation of a specialized agency.
- All Bearings need periodic maintenance such as Cleaning, Greasing/Oiling and Painting.
- A specialized agency must repair minor defects (surface cracks, tears, etc.) as per manufacturer recommendations.
- In the case of major defects (splits between elastomer and laminates, tears, bulging, deformation, etc.) is to be replaced.
- Replacement of bearing includes lifting the superstructure and lowering after replacement.
Also, Read: Bridge Inspection Types – Objectives and Guidelines
- Wearing Coat:
- Potholes of any extent should be repaired by filling the same material.
- If necessary, in the case of excessive cracking, bulging, or revealing renewal coat shall be provided.
- Removal of existing damaged wearing coat includes sealing of crack/porous concrete over deck slab and approach slab with Epoxy mortar/Epoxy injection through nipples, if any.
- Concrete Crash Barrier/Railing:
- Sealing of cracks should be done correctly.
- Work includes chipping of local surface, removing loose material, cleaning of reinforcement, adding extra reinforcement if required by welding, high strength cementitious grouting, replacing the damaged railing, painting etc.
- Existing RCC Railing shall be replaced with steel pipe railings.
- Railings shall be repaired with a better grade of concrete/micro-concrete after applying a bond coat.
- Barricading shall be provided to prevent any mishap.
Also, Read: Inspection of Bridges – Procedure & General Guidelines
- Expansion Joints:
- Works including cleaning of Expansion Joints and chipping of the local surface, if required, should be done as per the guidelines.
- Remove loose material, cleaning of reinforcement and structural steel, Adding extra reinforcement/plate by welding as required.
- High strength cementitious/epoxy grouting, etc., as per specialized agency’s recommendation.
- Drainage Spout:
- Choked drainage spout to be appropriately cleaned.
- Any damage and anchor bolts to be replaced as required.
- Approach Slab:
- Any damage should be repaired by high-strength cementitious grouting after removing the wearing course.
- Applying a new layer as necessary or replacement wherever necessary should be done for any type of settlement.