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Winter Grading

While site grading can be done during the winter months, it is more costly. Grading generally takes more time due to wetter soils and more “bad weather” days. Otherwise good soils are frequently wasted because of frost and higher moisture contents. To help successfully manage these conditions, these techniques can keep your project moving forward during the winter season:

As soils get wet and construction equipment drives across the site, the subgrade can lose strength. Grading the building pad high and crowned helps protect the slab subgrade from direct contact from heavy construction traffic. When the time comes to construct the slab, the additional soils are cut to subgrade elevation, with little or no additional undercut necessary. Another technique: grade to subgrade and place a well-graded stone base, such as crusher run stone. Compacted crusher run tends to shed water, whereas washed stone actually holds water.

Stabilize wet soils using cement or lime (quick or hydrated). Lime can help dry any soil and is used to chemically stabilize certain clays. Cement helps dry soil and doubles as a stabilizing agent. Properly employed, both lime and cement can be used to create nearly weatherproof subgrades.

Additional strategies to reduce the impact of weather during winter grading include:

  1. Work larger areas with each lift. Placing soil over a larger area allows more time for the soils to dry before the next lift is added.
  2. Work wet soils with light equipment. Wet soils can be compacted if they are within a compactable moisture range. Wetter soils can be worked by pushing them out into a lift with a self-propelled compactor from a single dump point.

Finally, there is simply no substitute for good housekeeping. The site should be sloped to clear water and quickly channel it away from the work area. It’s good practice to establish a network of roads to direct construction traffic away from unstable areas. Stabilize construction roads using crusher run or geotextiles, and regularly fill pot holes, rough areas, and wheel ruts to clear rain or snow melt. Equally important, contractors must enforce access discipline.

File Under: Geotechnical
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