Sand, gravel and hard rock aggregate are natural raw materials which, after treatment, are used in constructions such as roads, railway lines and buildings, and in diverse activities associated with building and construction sites.
Geological materials such as sand and gravel, clay and crushed rock are products of nature that mankind has learned to utilise to maximum effect over thousands of years.
These raw materials are so-called non-renewable resources, even though their re-use has gradually become more and more common.
Published: 05. February 2008