Blue metal is basically sand made out of rock quarried and crushed aggregate which varies in color from blue to black. This type of sand is also available in other sizes such as 5 mm and 10 mm as well. Basically, the blue metal sand is used for making concrete but as it is a clean type of sand it can also be used drainage materials such as the agricultural pipes. For constructing driveways, walking paths, drainage pits and fillers for gardening pots, blue metal 20 mm sand is used. The 20 mm is the larger size of the blue metal sand and works best with cement or asphalt for making a stronger concrete. Due to its good compressive strength, blue metal 20 mm sand is known make concrete which is a cheaper alternative for decorative dressings of driveways. Because of the ability to be compacted, blue metal 20 mm sand is used for creating a firm foundation for artificial lawns and prevents the growth of weeds and grass.