What is a primary advantage of using sand in foundations?

Using sand in foundations offers the primary advantage of quick drainage and strength. Sand has a coarse grain structure that facilitates easy movement of water through its voids. This characteristic is crucial in foundation design as it helps prevent excessive water accumulation, which can lead to weakening of the foundation and eventual structural failures. The ability of sand to drain quickly also minimizes the risk of soil saturation, which can be detrimental to the integrity of the foundation.

In addition to its drainage properties, sand tends to provide good load-bearing capabilities. When compacted, it can achieve significant bearing capacity, making it effective in supporting structures. This strength is particularly beneficial in construction, as it helps maintain stability under various load conditions.

Other options do not represent the primary advantages of sand in foundations. While sand does not have high cohesion, which is a characteristic of clay, its lack of cohesion is compensated by other beneficial properties, such as drainage and compactability. Although it may be less prone to erosion under certain conditions, this is not its most significant advantage compared to drainage and strength. Lastly, while cost can vary, the advantage is not simply about being cheaper than clay, as factors like performance and suitability for specific soil conditions significantly outweigh cost considerations in foundation design.