Advantages & Benefits of Exodermic® Bridge Decks

Light Weight Bridge Deck System

An Exodermic® bridge deck typically weighs 35% to 50% less than a reinforced concrete bridge deck that would be specified for the same span. Reducing the dead load on a structure can often mean increasing the live load rating. The efficient use of materials in an Exodermic® bridge deck means the deck can be much lighter without sacrificing strength, stiffness, ride quality, or expected life. Further weight reductions are possible using a lightweight concrete mix.

A lightweight Exodermic® bridge deck allowed the famous Eads Bridge over the Mississippi River in St. Louis to achieve an HS-20 load rating.

Rapid Bridge Deck Construction

Precast Exodermic® bridge decks can be erected during a short, nighttime work window, allowing a bridge to be kept fully open to traffic during the busy daytime hours. Cast-in-place Exodermic® bridge decks also permit considerable savings in construction time – the steel grid panels come to the site essentially ready for concrete. The steel grid component of an Exodermic® bridge deck acts as a pre-cut, pre-formed, stay-in-place form. Panels are quickly placed, and layout of the single mat of rebar is simple and straightforward, without the need for chairs or other aids in most cases. Cantilevered bridge decks can be formed without temporary supports.

Precast Exodermic® panels allowed 250,000 s.f. of the Tappan Zee Bridge to be redecked working only at night; all seven lanes were open from 6am to 8pm, with only 3 of 7 lanes out of service at night.

Low Maintenance Bridge Deck

An Exodermic® bridge deck is easily maintained with standard materials and techniques, since the top portion of an Exodermic® bridge deck is essentially the same as the top half of a standard reinforced concrete deck. If desired, any overlay compatible with concrete can be used, including latex modified concrete, polymer concrete, microsilica concrete, or a membrane with asphaltic concrete overlay.

The Exodermic® bridge deck on the 17th Street Causeway Bridge in Fort Lauderdale spans over 14 feet floor beam to floor beam (without stringers). The deck is composite with the floor beams and the top flanges of the main bascule girders, adding significantly to their structural capacity.

Overall Design Efficiency

An Exodermic® bridge deck adds substantially to the capacity of beams with which it is composite. On the 17th Street Causeway Bridge in Fort Lauderdale, for example, the main bars of the grid portion of the Exodermic® bridge deck are oriented parallel to traffic. The deck was made composite with the main box girder top flanges and the floor beams (no stringers were used). The substantial steel in the grid and the top reinforcing in the concrete slab added the equivalent of 3 1/2-inches of steel to the top flanges of the main girders.

Contact the DS Brown Company at 419-257-3561 about the Exodermic® bridge deck system.