Explanation

A rock or mineral fragment with particle size>2mm and a certain degree of roundness. Formed by long-term exposure of bedrock to the surface and mechanical weathering, crushing, and transportation. Due to the transportation of water and wind, it has a certain degree of roundness and is often accumulated in the piedmont, riverbed, and delta. The composition of gravel can be various magmatic rocks, sedimentary rock and metamorphic rock, or vein quartze. gravel with diameter greater than 5mm and good roundness is commonly called pebble or cobble. pebble is formed by long-term transportation, so its composition is rock with strong weathering resistance. Such as quartzite, chert, vein rock, jasper rock, agate, etc. The formation of gravel and pebble is related to a certain extent. It is an important coarse aggregate for preparing cement concrete. gravel and pebble are also used to pave roads and build walls in some antique building courtyards. In gravel and pebble used for building. It is required that the mud content is less than 2%, and it should not contain blocky clay. The mass fraction of needle shaped or flake shaped particles shall not exceed 25%; gravel and pebble with particle size of 5-12mm are ideal.

Classification