Bridge expansion joints are mandatory due to changes in volume of deck slab concrete caused by thermal expansion/contraction. Unless a reinforced concrete bridge deck slab is free to expand and contract, stresses are set up in the deck slab. Joints are therefore provided to relieve the stresses. Expansion joints permit the deck slab to expand and contract; they are equally suitable for concrete or asphaltic overlays. Loosening of expansion joints and crumbling of deck slab is witnessed in most road/highway bridges. Although the bridges' sub-structure is intact.
Correct installation of expansion joints is necessary depending upon their type and thereof size with respect to movements and gap width. Standard expansion joints can withstand a minimal amount of lateral, torsional, angular or concurrent misalignment. Care should be exercised to isolate and/or reduce vibration and dampen sound transmission.
The expansion joints are installed after the wear surface is finished. Flush fitting of top of the joints is achieved by the use of epoxy resins or high strength concrete in rebuts and beneath the joints. Use of normal concrete shouldn't be encouraged.
The use of both epoxy resins or high strength concrete and correct installation procedure is to prolong the useful service life of expansion joints. So is true for the bridge deck slab.
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