Cold Weather Paving

Compaction is of special concern during cold weather paving because as ambient temperatures decrease, HMA cool-down rates increase and the time available for compaction (before cessation temperature is reached) is reduced. Therefore, special care should be exercised when paving in cold weather to ensure the HMA is sufficiently compacted before cessation temperature is reached.

Most State DOTs affected by cold weather have temperature stipulations in the standard specifications that place special restrictions or prohibitions on cold weather paving. Two situations most often linked to inadequate compaction due to low ambient temperatures are:

1. Late Season Paving. Late season paving basically can result in paving during cold ambient temperatures. Paving thin lifts or using open-graded mix in cold weather can result in little time available for compaction. Using MultiCool, a 45 mm (1.8 inch) lift of dense-graded HMA delivered to the site at 135°C (275°F) and paved in 7.2°C (45°F) temperatures and a 16 km/hr (10 mph) wind will reach cessation temperature in about 16 minutes. Because of this, many northern tier States establish a “paving season” that significantly limits paving during colder times of year. For example, many northern state paving seasons are only mid-spring to mid-fall.
2. Night Paving Operations. Cessation temperature is applicable day or night. Naturally, this can be a problem for night paving even during warmer months because ambient night temperatures are often much lower than daytime temperatures.

Cold Weather Paving Practices

Cold weather paving is commonly taken to mean paving when the air temperature is below about 10°C (50°F). Night paving, used increasingly to reduce traffic delay, raises the same issues.

Planning

Where possible, paving in cold climates is best finished during the warm months. When late-season work cannot be avoided, some jobs suit it better than others: thicker lifts cool more slowly than thin overlays, so adding thickness to a thin overlay can lengthen the time available for compaction, and warm mix asphalt (below) gives a longer window. Before paving, the expected time available for compaction should be estimated, for example with mat-cooling software such as MultiCool or PaveCool (developed by the Minnesota Department of Transportation), so that production and compaction plans can be adjusted.

Hauling

Tarping a load has little effect on its average temperature but substantially reduces the cooler crust that forms on the surface of the load. If it is not remixed, that crust causes temperature differentials and low-density areas in the mat. Haul length is the main factor in deciding whether to tarp. Plant and paver production should be balanced so that loaded trucks are not left waiting at the paver.

Placement

HMA should not be placed on a frozen base. Handwork should be kept to a minimum, since raking and shoveling speed cooling, and handworked areas often take too long to place to be compacted adequately.

Compaction

The roller train and roller patterns should be chosen for the required density and the predicted time available, and rollers will usually need to work close behind the paver. Pneumatic tire rollers achieve a high degree of compaction quickly, but at low temperatures fresh mix tends to stick to cool tires. Skirts around the tires, tire heaters and mix additives can limit pick-up.

Warm Mix Asphalt

Warm mix asphalt, which is produced and placed at lower temperatures than HMA, suits cold weather paving. It can be compacted at lower temperatures, and because it starts closer to the air temperature it cools more slowly, so it gives a longer compaction window whichever warm mix technology is used.

@misc{pavint-cold-weather-paving,
  author = {{Pavement Interactive}},
  title = {Cold Weather Paving},
  year = {2026},
  publisher = {HeadLight},
  howpublished = {\url{https://pavementinteractive.org/reference-desk/construction/compaction/cold-weather-paving/}},
  note = {Accessed [date]}
}