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

Cold weather concrete on Vermont DOT projects is defined as concrete placed or cured when ambient air temperature is below freezing or below 40°F for 8+ hours. Placement is prohibited below 10°F without Engineer approval. A cold weather concrete plan must be submitted and approved before placement. No concrete can be placed in superstructures or thin sections under cold weather conditions. Materials must be heated uniformly (aggregates ≤150°F, water ≤140°F if mixed with aggregate before cement). Forms must be thawed and kept above 32°F, with a ≤40°F temperature difference between forms/substrate and concrete. Protective housing must fully enclose the structure, be heated to maintain concrete temperature >50°F, and kept continuously wet during curing. Enclosures must be heated to keep concrete temperature between 50°F and 160°F, with a gradual cooldown over 48+ hours. No antifreeze compounds or frozen materials can be used.

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