Section 4: Bridge Maintenance Actions
Anchor: #i1001447Bridge Joints
Joints are typically placed at each end of the span or for bridges built in the last 40 years, at the ends of bridge units to accommodate bridge movements related to temperature change. A sealed joint creates a barrier which keeps the joints clean and free of debris to allow for the needed movement, protects the beam ends and bent caps from deterioration related to deicing salt use and other contaminants and prevent debris build up accumulating around the bearings which is also problematic. Maintaining bridge joint seals is the most beneficial activity to prolong the life of the bridge.
When there is damage to a steel expansion joint system, removal of loose steel joint members is recommended. Typically, removing the loose steel pieces will not create large openings in the roadway, except in the case of finger joints. If finger joint plates come loose, contact the Bridge Division for support. Never weld additional steel members across an open expansion joint. Bridging an open joint with welded steel members will cause additional damage to what may not be damaged.
Anchor: #i1001458Bridge Bearings
Bridge bearings accommodate load transfer to the supports as well as allow for thermal movements associated with temperature change. Debris accumulation around moving bearing devices can result in malfunction. Keep debris from accumulating around bearings by joint maintenance. Additionally, remove debris that has accumulated around the bridge bearings and off the tops of caps.
Anchor: #i1001468Bridge Drainage
Flow of water off and toward bridges can cause significant undermining of the bridge approaches and slope protection. Where concrete riprap was placed as slope protection, water migrating under it will erode the fill and potentially extend under the abutment cap and approach slab and roadway. Paying careful attention to early signs of erosion can prevent significant loss of support to the approach roadway which can require closure and extensive repair to address.
Anchor: #i1023568Bridge Drains
Drains cast into bridge decks to release water from the roadway appear to collect debris easily which prevent the drains from functioning properly. When joints are maintained and kept sealed, open drains become essential to allow drainage off the roadway at desired locations.
Anchor: #i1023614Asphalt Treated Surfaces on Bridges
It was common practice to place seal coats and asphalt overlays on bridges in the past. TxDOT promoted the practice of placing the Texas Bridge Deck Protection System, consisting of a two-course surface treatment followed by an asphalt overlay. This practice is no longer considered effective to deter deck deterioration and contributes to other issues such as: it lowers the bridge rail height from the roadway not allowing the rail to function as designed under impact; the asphalt ravels at expansion joints resulting in costly bridge joint treatment; and it creates in-effective joint sealing. Placing asphalt treated surfaces on bridge decks is no longer recommended, but it is recommended to maintain the asphalt surface by milling down to the bridge deck surface before applying the new asphalt treated surface. When asphalt extends over bridge expansion joints, it is recommended to saw cut the asphalt two-thirds overlay depth and seal with a hot pour rubber seal.
Anchor: #i1023709Penetrating Concrete Surface Treatment
Applying penetrating concrete treatment (silane or other penetrating sealers) to concrete surfaces is beneficial to reduce deicing salts from penetrating the concrete. When salt reaches the reinforcing steel, it will corrode and result in spalling concrete. The most effective means of ensuring performance from silane is proper concrete surface preparation prior to application. Shot blasting the surface is believed to be the best surface preparation treatment, then abrasive blasting. Lastly water blasting is also allowed, but intensity of water must be sufficient to prepare the surface to absorb the sealer plus the concrete must be allowed to dry out sufficiently to accept the material which makes this the least desirable surface treatment. When traffic control is set up across a bridge for roadway work, it is a good practice to address the concrete bridge deck while mobilized. Maximum recommended reapplication interval is ten years.
Anchor: #i1023763Washing Bridge Decks
Sweeping and power washing bridge decks without overlays is recommended after the winter season concludes if salts were applied during the winter season.
Anchor: #i1023788Concrete Spall Repair
The most noticeable and problematic concrete spalls occur on the bridge deck surfaces. When spalls occur on the driving surface of the bridge deck, investigation on the underside of the deck (soffit) at that location should occur to verify the distress is contained to the upper surface, which is usually the case. If significant cracking of the soffit of the deck corresponds with the upper surface spall, immediate action may be necessary to address the situation. The main short-term issues related to riding surface spalling are driver disruption and potential reinforcing steel failure.