Technical Support
Structural Expansion Joints
Structural Bearings
Structural Expansion Joints
Pre Stressed Slab
Maintenance Manual of Strip Seal

Expansion Joint and its components are continually exposed to natural element, eg. Temperature changes, rain, snow, moisture, ozone, carbon dioxide and ultra violet rays and elements that are introduced by humans like Traffic impact, chemical influences such as Industrial pollutants and de-icing salts. The combined effect of these elements on the joint component is a steady and unavoidable deterioration process.

That is why regular inspection and maintenance are vital measures for a long life span of expansion joint system.

Inspection of Expansion Joints at site is required from time to time to ascertain the performance of the joints. Periodic nominal maintenance of joints shall be carried out in order to ensure better performance and longer life of joints. The joints are required to be inspected at an interval of one year for the first five years and at an interval of 2 years thereafter. However, the joints shall also be examined carefully after unusual occurrences like heavy traffic, earthquake, cyclones and battering from debris in high floods.

The followings are recommended maintenance elements and actions which are considered necessary to monitor and upkeep the joints:
Debris accumulation in the joint gaps, if any. :- The maintenance shall be preceded by careful cleaning of the expansion joints to permit free movement avoiding incompressible clogging of the joint due to debris accumulation. All accumulated foreign objects shall be cleaned either by pressurized air or by water jet. It is to be noted that high water pressure (above 100 bar ) or heated water (above 25 degree C) shall not be used.
Riding comfort over the Joints. :- The alignment of the joints is a helpful indicator for the general behavior of the Superstructure and Substructure concerning movements as tilting rotation etc. In general, the deviation of the alignment can cause a reduction of driving comfort for the vehicles or can have a negative influence on the joint system as a whole.
Especially two points required to be inspected with care are:
The alignment in transverse direction (referring the joint)
The vertical alignment measured along longitudinal direction with respect to the level of adjacent road surface.
The alignment in transverse direction shall be measured with a 4 m straight edge. The deviation between the joint and straight edge should not be more than 5mm. The vertical alignment measured along longitudinal direction with respect to the level of adjacent road surface should not be more than 3%.
Measurement of Movement :-
During maintenance at site, measurements are required to be taken and documented to compute its movement and rotation values in relation to their design values to ascertain whether the performance of joint are satisfactory. To ascertain maximum movement, measurement should be taken once during peak winter (early morning) and once during peak summer (afternoon) and corresponding atmospheric temperature should be recorded. The recorded value of movement shall be compared with design values.
Measurement of Dimensions :-
Overall dimensions of the joints are required to be measured and compared with the actual dimensions to ascertain any excessive stress or strain on the joints.
Evidence of Locked in Condition :-
If any movable or rotating part of a joint is found to be in locked -in / jammed condition, necessary rectification measure shall be taken immediately. Distribution of width of surface gaps (if any) provided to accommodate movement should be checked over the length of joint. Any abnormal variation of surface gap width over the length of the joint and / or the distribution of the gap width beyond the design limits, if detected, the joint should be thoroughly checked for the locked-in condition in order to detect mechanical obstruction and possible remedial measures should be taken immediately.
Evidence of Corrosion :-
The condition of corrosion protection shall be checked carefully. Early detected and repaired damages will certainly avoid expensive repairs on a later date. If corrosion of any part of exterior exposed steel surface of the joint is detected, following measures may be taken. In addition, the root cause of defect should be searched and proper action should be taken to avoid recurrence of the problem.
Detect affected part.
Wire brush the affected portion to clean of its rust.
Apply protective coating of paint.
Condition of the Adjacent Bridge Structure :-
The Bridge structure adjacent to the Joint shall be examined for the following common defects, which may lead to further damage of the joint. If damages are detected they must be repaired as soon as possible to avoid further source of damage.
Spalled concrete.
Broken off edges.
Cracks or fissures in the structure.
Rust spots on the concrete surface.
Exposed Reinforcement.

Condition of the Sealing Elements :-
The condition of the Elastomeric unit/ seals shall be carefully inspected to uncover possible defects like loose, torn, split, cracked, damaged or cut etc.

If any one of the above defects appears, remedial action should be taken the degree of which depends on the present defects. In general, following remedial action should be taken:

Replacement of damaged part.

Water Tightness / Evidence of Leakage :-
Leakage of water together with temperature and chemical reaction might be a reason for following damages beside an unpleasant appearance:

Destruction of the bridge structure, broken concrete.
Corroded steel parts, e.g. reinforcement, drainage pipe.
Rust staining, dirt staining.
If evidence of leakage is detected remedial actions must be taken by replacing the seal element or applying sealing element as per the instruction of the joint manufacturer or tightening of the loose component depending upon the cause of the leakage.

Evidence of Noise :-
Abnormal rollover noises generated by the joint under traffic load can be regarded as the indicator for the condition of the joint and also for the adjacent bridge structure. Abnormal noise may be caused by loosened and / or damaged joint components, loosened bolts, metal to metal contact due to damage of joint components.

If such an abnormal noise is noticed, the origin of noise should be probed first and depending upon that, remedial works shall be taken up by tightening the loose fixing and / or replacing the damaged components.

Destruction of the bridge structure, broken concrete.
Corroded steel parts, e.g. reinforcement, drainage pipe.
Rust staining, dirt staining.

Visible Damage of the Joint Components :-
Any visible damage of joint component, welded and bolted connections as well as connection of joint with bridge structure if detected during inspection, proper remedial measures should be taken immediately in consultation with the joint supplier.


Results & Actions :-
The results of every inspection have to be recorded in the inspection report and shall be classified in each case into the following types of action:

No action.
Further measurements / long-term monitoring or design analysis needed (e.g. considering extreme temperatures / exposures, variation of loads etc.). Actions to be outlined in a report.
Minor repair works e.g. cleaning, repainting etc.
Repair or replacement of entire joint or components of the joints. Actions to be outlined in a report. In case of defects where the cause of necessary actions cannot be determined by the inspecting person or the responsible bridge engineer, the Expansion Joint manufacturer should be consulted.