In road, construction, water and other basic projects, rock material is one most kind basic project material. All kinds of broken stones with different particles are used most, which include larger size broken stones and smaller size gravel. These broken stones are mainly used for concrete aggregate. For example, in the cement and concrete, aggregate using quantity covers over 80% of the total concrete. A lot of broken aggregate, especially the larger broken stones, mainly acquired by man-made production, that is the broken stones produced by using crushing and screening equipments.
When the project scale is much smaller, also can meet the project need by collecting natural gravel. In general, most of the natural sand and gravel are round, and the surface area is small, while manual-produced broken stones are with edges and corners and larger surface area. So the broken stones, cement, and asphalt by manual-produced can join better, and the concrete quality is very high. Meanwhile the broken stones particle are uniform, and also can produce different specifications according to need, for this, the natural gravel materials can't reach in quality.
In the project that required higher concrete quality, the used sand and gravel is produced by machinery. In mining project, crushing and screening is the main equipment for main factory, and it is also widely used for ore crushing, screening, grading operation. In building material industry, such as producing cement, glass and refractory material, most of them use crushing and screening equipment to deal with raw material.