drainage aggregate造句

The second farm at the Brooklyn Navy Yard has a green roof system which consists of a lightweight drainage aggregate, with a layer of similar felt above to filter the solid particles and keep the system together.
The use of these materials has become increasingly more common due to their ease of use which eliminates the need for transporting and laying stone drainage aggregate which is invariably more expensive than a synthetic drain and concrete liners.
It's difficult to find drainage aggregate in a sentence. 用drainage aggregate造句挺难的