Natural sand is rounded by water. Crushed sand is made in the plant. Grains smaller than 4 mm are sand. The 4 to 15 mm cut is gravel 1.5. The 15 to 25 mm cut is gravel 2.5.
Use
Crushed andesite sand is used in concrete and in civil layers where a manufactured, consistent grain is required. Fines content is declared. It is not a substitute for railway ballast.
Shape and surface
Crusher-made sand has angular faces and a rougher surface than water-rounded sand. That texture can improve paste bond, while the extra surface area can increase water demand. Mix designers balance the fine aggregate curve, crusher dust, moisture and admixture dosage rather than judging the material by colour.
Specify the use
For concrete, ask for the target grading, methylene-blue or clay indicators where relevant, moisture at dispatch and a representative sample. For unbound layers, state the compaction and drainage requirement. “Sand” without a size band or end use is not a technical specification.
