Machine-made sand refers to the sand produced and processed by sand making equipment and other additional equipment. The finished product is more standard and can be produced and processed into sand of different rules and sizes through different technological requirements, which can better meet daily needs. .
Good machine-made sand has performance not inferior to natural sand, and can fully meet the high requirements of modern concrete for strength and performance. Compared with river sand, it also has better engineering applicability. Of course, the premise is high-quality artificial sand, and inferior machine-made sand is not allowed to be used in engineering construction projects. So how to produce high-quality machine-made sand?
1. Source material selection
Man-made sand comes from various rocks, and its properties depend on the natural properties of the base material. In order to produce high-quality machine-made sand, it is necessary to ensure that the properties of the source material itself meet the requirements. Usually good source materials are all kinds of rocks with high strength, low content of weathered stone and soft rock, low content of rock interlayer and surface clay, and low content of harmful substances.
At present, the types of rocks that are widely used in my country include river pebbles, pebbles, granite, limestone, basalt, andesite, diabase, marble, and sandstone. Different rock materials produce machine-made sands that vary in strength and particle size, as well as in uses. Therefore, when producing machine-made sand, the type of source material must be selected according to the application; and different raw materials should be equipped with crushing systems according to the specific crushing and sand making requirements.
2. Particle shape control
Many concrete productions have strict requirements on the shape of machine-made sand grains, which require regular rounded grain cubes with certain edges and corners to increase the mutual locking force between the grain sizes and make the possibility of displacement of asphalt and materials or cement and materials The reduction is small; and the inferior machine-made sand with poor grain shape does not meet the production requirements.
The cause of poor particle shape is largely related to the selected equipment. As long as the selected equipment is reasonable, this problem can be easily solved. Generally, Dahua Heavy Industry PLS impact sand making machine with shaping function can be used to produce high-quality machine-made sand.
3. Grading control
The gradation of machine-made sand refers to the matching ratio of sand particles. If it is sand of the same thickness, the gap between them is very large; if the sand of two particle sizes is matched, the gap between them will be reduced; if the sand of three particle sizes is matched, the gap will be smaller. It can be seen that the porosity of machine-made sand depends on the matching degree of particle sizes of sand materials at all levels.
Well-graded machine-made sand requires that the particle size ratios of all levels meet the requirements, and the ratio of coarse particles, intermediate particles and fine particles cannot exceed the standard. Choosing suitable sand making and screening equipment can not only control the gradation reasonably, but also make the sand meet the gradation requirements of Class II sand.
4. Fineness modulus control
The fineness modulus mainly reflects the thickness of the machine-made sand. The larger the fineness modulus, the coarser the sand. According to the fineness modulus, machine-made sand is generally divided into three specifications: coarse, medium and fine sand, and is divided into Class I, Class II and Class III according to its technical requirements. At present, the fineness modulus of machine-made sand on the market generally requires Zone 4 and 2 (medium sand, fineness modulus is 3.0-2.3), but the finished products of many sand making production processes are too coarse. In addition to adopting a reasonable sand production line process to adjust the fineness modulus, the fineness modulus can also reach 3.0-2.3 through the mixing of coarse sand and natural sand zone 1 (fine sand).
When producing machine-made sand, cone crushers or impact crushers should be used for crushing Type I and Type II machine-made sand; cone crushers, vertical impact crushers and impact crushers can be used for Type II and Type III machine-made sand. It is recommended to use a square hole screen as much as possible for the screen type, which is very beneficial to grain shape control. The use of round hole screens or long strip screens can be reduced, and the screen is often monitored for blockage and damage, so as not to affect the fineness modulus. Stablize.
5. Stone powder content control
In the process of machine-made sand production, it is inevitable to produce stone powder. Reasonable stone powder content can fill the void and greatly promote the performance of concrete. The high content of stone powder will not only affect the performance of concrete mortar, but also cause waste of resources and environmental pollution. Reasonable stone powder control process can not only reduce the stone powder content, but also can adjust and control the sand stone powder content of the finished mechanism between 5%-%15.
Generally, the dry sand making process adjusts the range of stone powder content by adjusting the machine-made sand equipment parameters, while the wet process adjusts the stone powder content by adjusting the amount of water injection and the speed of the sand washing machine.
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