What percentage swell is associated when sand or gravel is disturbed?

The percentage swell associated with the disturbance of sand or gravel is typically around 12%. This figure reflects the fact that when granular materials like sand and gravel are disturbed—such as during excavation or grading—they can expand or "swell" due to changes in their density and packing arrangement. The swell occurs because the materials can create air pockets and exhibit less compaction after being moved, resulting in a volume increase.

In the context of construction and excavation, understanding this swell percentage is crucial for accurate calculations related to material volumes, site preparation, and ensuring proper drainage and foundation stability in future construction. Each type of soil or aggregate has unique characteristics, but a swell percentage of around 12% serves as a common standard for sand and gravel which helps engineers and builders plan accordingly.