Shingle can be produced from either land-based or marine-dredged ballast, the material will be washed, crushed and screened into the different grades. Sub-angular shingle is mainly used for drainage and driveways.
Rounded shingle is produced from land-based ballast. The material will be washed and screened but no crushing will take place before grading. Rounded shingle is mainly used for pipes, tanks and on roofs.