Expanded clay aggregate

Expanded clay aggregate (ECA) is rocks made from little balls of clay that have been heated up very hot, like in a furnace. This heating process makes the clay balls puff up and expand like popcorn, so they are called expanded clay aggregates. They are used in gardening and construction because they are lightweight, but still very strong. Because they are so light, they don't add too much weight to whatever they are used in, but still give it strength. They are also a good way to improve drainage in soil and help make sure plants get enough air and water.