Moisture Content Fluctuation in Minnesota Road Subgrades
Matthew Henderson
University of Minnesota Duluth
Keywords: Subgrade, moisture
Abstract
Fluctuation in subgrade moisture content of road subgrades is known to reduce the quality and lifespan of the driving surface. This paper examines possible specific sources of moisture fluctuation in subgrade soils. Groundwater, precipitation, and seasonal cycles are all investigated to determine their influence on long-term and continuous moisture fluctuations. While precipitation’s impact is minimal and probably only affects small continuous water variations, groundwater can greatly change subgrade moisture. The freezing and thawing experienced in cold climates appear to have the most destructive impact on driving surfaces. Minnesota offers an environment where all possible factors discussed in this paper are abundant. Additionally, Minnesota’s soil makes it particularly vulnerable to subgrade moisture problems. Minnesota’s roads are in desperate need of renovation, and developing a method to account for subgrade moisture variations could save time and money. Future testing is recommended to determine if a thicker road section would be worth the additional cost to protect roads against subgrade moisture variation.
