Sand gravel is one of the main ingredients of concrete and mortar, which is the bulk material in civil engineering. Sand making machine is the main sand production equipment. So we should choose the high quality sand making machine for high quality sand production.
Sand is generally divided into two categories, natural sand and artificial sand. Rock particle size less than 5 mm is formed natural sand under natural conditions (mainly rock weathering). Artificial sand is machine-made sand, it is formed with rock particles size less than 4.75 mm. It does not include the soft rock, weathering rock particles. The specifications of sand gravel according to the fineness modulus of sand (the degree of natural sand grain size and the thickness and index) is divided into coarse sand, medium sand and small sand. Coarse sand, fineness modulus is 3.7-3.1, the average particle size is more than 0.5 mm. Medium sand, fineness modulus is 3.0-3.0, and the average particle size is 0. 5-0.35 mm. Fine sand, fineness modulus is 2.2-1.6, the average particle size is 0.35-0.25 mm. Ultra-fine sand, fineness modulus is 1.5 to 0.7, and average particle size is below 0.25 mm.
The bigger fineness modulus is, the coarser particle size is. The fineness modulus of normal concrete is 3.7 to 1.6, with medium sand advisable, or small amount fine sand with coarse sand, the ratio of 4:1. The grain size distribution of sand is refers to the proportion of sand grain size. If it is the same size of sand, the gap is the largest, the two size of sand mixed, the gap becomes smaller, the three size of sand mixed together, the gap becomes smaller than the two size. Therefore, the gap of the sand depends on how much the collocation of sand material particle size at all levels. Graded grave can not only save cement, also increase the compactness of concrete and mortar and strength.