Which type of soil is typically worst at handling frost heave?

• A. Gravel
• B. Sand
• C. Silt
• D. Clay

Answer: (C)

Soil types vary in their ability to handle frost heave due to differences in their physical properties, particularly their moisture retention and expansion characteristics. Clay is recognized as the soil type that is the worst at handling frost heave.

The reason behind this lies in clay's high plasticity and fine particle size, which allows it to retain water more effectively than coarser soils like gravel and sand. When the temperature drops, moisture in the soil can freeze, expanding significantly in volume. This expansion exerts pressure on nearby structures and can lead to significant damage over time. Since clay has a tendency to swell when it freezes, it becomes particularly problematic in areas prone to frost.

Additionally, clay's low permeability means that even when water is present, it does not drain quickly. This retention of water can exacerbate the potential for frost heave, as the moisture is trapped within the soil where it can freeze and thaw repeatedly. This characteristic makes clay susceptible to repeated cycles of expansion and contraction, ultimately compromising the structural integrity of roadways and foundations built on or within this type of soil.

In contrast, gravel and sand have larger particles and greater void spaces, allowing for better drainage and less moisture retention, making them far more resilient against frost heave.