Modelers David Popp, Brian Schmidt, and Bryson Sleppy continue the scenery process on their T-TRAK modules by adding gravel ... places we had Sculptamold to clean off the track's plastic roadbed.

Some may categorize gravel into categories, such as fine gravel, medium gravel, and coarse gravel, based on the average diameter of the stones. Gravel can range anywhere between 1/16 of an inch ...

large objects are removed by screening using grids a coarse filter bed made from clean sand and gravel removes larger insoluble grit particles aluminium sulfate is added to clump smaller insoluble ...