Which soils are best at handling frost heave?

• A. Gravel and sand
• B. Silt and clay
• C. Clay
• D. Sand only

Answer: (A)

Gravel and sand are the best types of soils for handling frost heave due to their structural properties and drainage characteristics. Porosity and permeability are crucial in managing frost action; gravel and sand allow water to drain away more easily than finer soils such as silt and clay. When soils freeze, the moisture within them can expand, leading to frost heave, which can cause significant damage to pavements and foundations. The coarser particles in gravel and sand provide larger voids that facilitate drainage and reduce the amount of water that can accumulate and subsequently freeze.

In contrast, soils like silt and clay retain water more effectively, which can increase the potential for frost heave. Clay, particularly, with its fine particles and low permeability, tends to expand significantly when wet and frozen, exacerbating the heaving effect. While sand does have good drainage properties, it is when combined with gravel that the best outcomes for frost resistance occur, as the mixed gradation allows for a stable base that minimizes heaving. Therefore, gravel and sand are optimal choices for applications in frost-prone areas.