What are the rules for placing concrete in cold weather on Missouri DOT projects?

"703.3.10 Cold Weather Concreting. Concrete work shall proceed on all structures, except bridge superstructures, whether or not heating will be required, unless it can be definitely established that the overall progress of the project will not be affected. Placing of concrete in the superstructure of a continuous or monolithic series of spans once begun shall be continued within the provisions of cold weather concreting procedures until all the concrete in that series is placed. Concrete placed in cold weather shall be protected from freezing during the curing period. Concrete shall not be placed on frozen ground, or against steel or concrete surfaces with temperatures lower than 35ºF. Concrete shall not be placed where the ambient temperature is below 35ºF without prior approval from the engineer. Concrete in bridge superstructures shall not be placed where the ambient temperature is below 40ºF without prior approval from the engineer." [1] "703.3.10.1 The aggregate, the water, or both, shall be heated during the season when the atmospheric temperature may drop below 40ºF. Aggregate shall not be heated higher than 150ºF. The temperature of the aggregate and water combined shall not be higher than 100ºF when the cement is added. Any method of heating during the mixing of concrete may be used, provided the heating apparatus will heat the mass uniformly and avoid hot spots that will burn the material. The temperature of the concrete at the time of placing in the forms shall be no lower than 45ºF for concrete in footings, massive piers and abutments, or less than 60ºF for" [1] "703.3.10.2 When the ambient temperature is below 40ºF, with the approval from the engineer, curing of superstructure concrete, substructure units above ground surface, retaining walls and box culverts of more than 15 square feet opening shall be accomplished by methods that will prevent concrete from freezing. The minimum compressive strength required for form removal and ending protection from freezing shall be in accordance with Sec 703.3.2.13 . The contractor shall furnish temperature monitoring equipment and accessories that demonstrate to the engineer that concrete has been protected from freezing, with payment for such equipment and accessories included in the contract unit price for concrete. Exposed surfaces of the concrete shall be kept moist during the curing process. Substructure concrete below ground surface may be protected by submersion provided the temperature of the water is maintained between 40° and 80° F for seven days." [6] "703.3.10.3 Concrete headwalls for pipe culverts, drop inlets and box culverts of 15 square feet or less openings, may be placed without air temperature limitations, but the contractor shall be responsible for proper protection from freezing during placing and curing of the concrete." [6]

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