Bedrock aggregate is aggregate cut from solid rock that is usually used as crushed (or rarely as non-crushed) bulk for various construction purposes. Depending on the use, bedrock aggregate can contain different kinds of fractions that can vary in size from fine grains to large boulders. Soil is loose rock aggregate stratified on top of the bedrock, and the grain size and sorting of soil vary due to stratification and generation. In this context, "soil" refers to sorted sand and gravel strata. The typical uses of rock aggregate include road and railroad construction, tarmac, concrete products and housing construction. The future prospects of rock aggregate supply also include that rock aggregates will be used more frequently to replace gravel and sand reserves. Examples of such aggregates include crushed till, waste rocks from the mining industry, and different recycled materials.
GTK has systematically surveyed rock aggregates since 1989 and a great portion of Finland has been mapped during the POSKI projects. The last POSKI project is being planned for the Lapland region.