Bridge Deck Rehabilitation
Strategies and Criteria
In general, PCC bridge decks develop problems caused by a) initial shrinkage and thermal cracking, b) poor placement and ride initially, c) drainage issues caused by settlement, live loads and wear, d) cracking and spalls caused by reinforcement corrosion induced by deicing salts or carbon dioxide infused through porous, cracked PCC surfaces, e) reduced skid resistance caused by high traffic wear and f) mechanical damage and wear from snow chains and studded tires.
One rehabilitation strategy has been to apply overlay technology to protect the bridge deck and super-structure and return ride quality for the traveling public. Choosing the right overlay material has been a quest since the 1960's. Various products have been evaluated, extensively, to solve the varying problems that occur in bridge deck concrete overlays. Products like low slump concrete, asphalt concrete with membranes, latex modified concrete, high performance concrete, fly ash modified concrete, silica fume modified concrete, and other polymer modified concretes have been used and have been more or less successful.
Clearly, engineers need to understand the requirements for a protective overlay in order to select a product that not only meets the criteria but also has proven serviceability over a substantial amount of time.
An overlay, designed as part of a rehabilitation strategy to extend the serviceable life of a bridge deck, should meet the following criteria:
- Superior adhesion to substrate concrete deck- short and long term
- High mechanical properties
- Seals deck surface from ingress of deicer salts or other environmental contaminants
- Able to return traffic quickly
- Crack-free
- High abrasion resistance to high traffic conditions, snow chains, studded tires
- Proven long term performance in a broad range of environments
- Maintenance of skid friction values
- Follows a placement process that results in a uniform cross section thickness and returning a good final ride quality profile
- Easy to inspect, repair, and maintain
For more information click here for: aashto-agc-artba task force 34: Guide Specifications for Polymer Concrete Bridge Deck Overlays