Internally Sealed Concrete for Bridge Deck Protection: Interim Report No. 1

About the report:

The study reported here was performed to extend the body of knowledge concerning the use of internally sealed concrete to protect bridge deck reinforcing steel. A laboratory determination of the properties of the wax and concrete used and a field evaluation of a method of heat treatment were made. The experimental structure was a three-span bridge on which internally sealed concrete was applied as an overlay. The concrete mixture had good placement characteristics and resulted in good properties for internally sealed concrete. It had a water to cement ratio of 0.47, a cement content of 752 lb./yd.³ (446 kg/m³), a wax bead content of 114 lb./yd.³ (68 kg/m ³), and included 4% to 6% entrained air. A similar mixture should be used on any internally sealed decks to be constructed. The heat treatment should be modified to prevent thermal cracking by heating entire span lengths and by heating only when ambient temperatures of 60°F (16°C) and higher have been sustained for one day. If these recommendations can be implemented, internally sealed concrete should be considered an acceptable system for protecting bridge decks. A decision concerning the use of internally sealed concrete should not be made until further evaluations can be made of pattern cracking that has appeared to varying degrees on both the experimental and control spans.

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