Spring thaw, also known as thaw weakening, occurs in early spring when the temperatures are beginning to rise, and the snow begins to melt. Spring thaw is also the time when the most damage to asphalt pavements can occur. During the winter, water within the pavement and aggregate base freezes from the surface of the pavement down to the subgrade. Spring thaw occurs as the frozen pavement begins to thaw from the surface of the pavement down to the subgrade. While the subgrade is still frozen, water from the thawing pavement is trapped in the materials below the pavement. These saturated materials are significantly weaker, allowing heavy loads to easily damage the pavement. This is why many states implement spring load restrictions. The Minnesota state DOT (MnDOT) has estimated over $10,000,000 in savings each year, due to the implementation of the spring load restriction program.
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