Synthetic sand is the main raw material in the construction industry at present, and it occupies an increasingly important position in the current time when natural resources are increasingly scarce.This article mainly introduces the raw materials, types, particle type requirements, particle grading and production methods of synthetic sand.
What is synthetic sand?
Sand and gravel are important raw materials for the construction industry and also a very important strategic resource. Sand and gravel can be divided into natural sand and synthetic sand. Natural sand refers to rock particles with a particle size of less than 5 mm formed under natural conditions. Synthetic sand refers to sand processed through machine-made sand and other auxiliary equipment.
What raw materials are generally used for synthetic sand?
Cobblestone: widely used and good texture synthetic sand raw material, its compressive strength, grain shape, and color are almost comparable to natural sand.
Bluestone: It has been used as the raw material of crushed stone before, but the finished product processed by the sand making machine is also very good, and the stone powder produced along with the production can also be used as synthetic sand after cleaning.
Limestone: It is widely distributed in nature and easy to mine. Like bluestone, it can be used as a raw material for synthetic sand and gravel at the same time, but there may be too much stone powder.
Granite: It is a high-quality raw material for sand making with high quartz content and low sulfide content, but like limestone, it needs to solve the problem of dust.
Construction waste: The synthetic sand produced by it is generally used to fill foundations and produce mixed recycled aggregates. The price in the market is low, but the price of its raw materials is also low.
What types of synthetic sand are there?
According to the fineness modulus, synthetic sand is divided into three types: coarse, medium and fine. The fineness modulus of coarse synthetic sand is 3.7 to 3.1; the fineness modulus of medium synthetic sand is 3.3 to 3.0; the fineness modulus of fine synthetic sand is 2.2 to 1.6.
Divided according to technical grades, synthetic sand is divided into three grades, and each grade has a different scope of application.
The first type of synthetic sand is suitable for concrete with a strength class greater than C6
The second type is suitable for concrete with strength grade C30 to C60 and frost resistance, impermeability or other requirements, hydraulic concrete.
The third type of synthetic sand is suitable for concrete and construction synthetic mortar with a strength grade less than C30.
What does the particle gradation of synthetic sand mean?
The particle gradation of synthetic sand refers to the matching ratio of sand-sized particles. If it is sand of the same thickness, the gap between them will be larger; 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.
Therefore, it can be concluded that the porosity of the sand depends on the matching degree of the particle sizes of the sand materials at all levels. Well-graded sand can not only save cement, but also improve the compactness and strength of concrete and mortar.
Granular requirements of synthetic sand?
Generally speaking, the particle size of the crushed material is required by the general mining crusher to be fine. Generally speaking, the needle-like material is easier to be ground when it enters the crusher. However, the requirements for building gravel are just the opposite, and there are strict restrictions on the proportion of needle flakes.
The main reason is that the cube particles have edges and corners, and the edges and corners can play the role of mutual locking between particles. At the same time, cubic particles have stronger adhesion and occupy a larger surface area than needle-like particles and round particles.
What are the production modes of synthetic sand?
At this stage, it is mainly divided into two types: dry sand making and wet sand making.
Wet sand making
Wet sand making refers to the sand produced and processed in the sand making machine equipment. After being cleaned by the sand washing machine, the quality of the finished product is close to that of river sand, the fineness modulus is between 2.8 and 3.1, and the content of stone powder is less than 3/100, without mud powder, very suitable for high-strength concrete. The advantage of wet sand making is that there is basically no dust in the production process, and with fine sand recovery equipment, the finished product has reasonable particle grading and excellent appearance.
Dry sand making
Dry sand making means that the sand produced by the sand making machine does not need to be cleaned by the sand washing machine. After being screened by the screening equipment, the sand that meets the requirements can be directly sent to the finished product pile by the conveyor, and the sand that does not meet the requirements can be returned to the finished product pile. Go to the sand making machine for reprocessing, and thus cycle.
During dry sand making, the staff need to pay attention to the mud content and water content of the raw materials. When the mud content is too large, it will affect the performance of concrete. If the mud content is too high, the mud content should be reduced before production or during production. The advantage of dry sand making is that it will not be limited by water sources and the environment, and can guarantee supply to a large extent. Compared with wet sand making, the investment in dry sand making in the later stage is relatively small.
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