Sand and gravel aggregate, as the basic component of concrete, plays an important role in concrete buildings. On the one hand, it is because of the large demand for it, which requires about 1.5 cubic meters of aggregate per cubic meter of concrete. On the other hand, It is because the quality of the aggregate directly affects the quality of the concrete dam. Therefore, under the demand of high-performance concrete, high-quality sand and gravel aggregates have become inevitable.
The performance of high-quality machine-made sand is no less than that of natural sand, and it is more suitable for modern concrete that requires high strength and performance. Compared with river sand, it also has better engineering applicability. So how to produce high-quality sand and gravel aggregate?
1. High-quality material selection
The quality of parent rock directly affects the quality of machine-made sand and gravel. To produce high-quality machine-made sand and gravel, it is necessary to ensure high-quality material sources. Usually high-quality material sources are rocks with high strength, low content of weathered stone and soft rock, low content of interlayer and surface clay, and low content of harmful substances.
The parent rock should not have potential alkali-aggregate reactivity, and it is advisable to use limestone, dolomite, granite, basalt, etc. that are clean, hard in texture, free of soft particles and weathered fossils.
2. Particle shape control
Inferior mechanisms have poor sand grain shape, sharp edges and corners, and excessive needle flakes. This situation is mainly caused by inappropriate selection of processing equipment. Many companies only use hammer crushers and fine jaw crushers in order to save investment costs. Machines are used to crush and make sand, and the finished product has a poor grain shape.
If possible, choose suitable equipment to make sand, and this problem can be better solved. The selection of BTMA Machinery PLS series vertical impact crusher equipment can produce more high-quality machine-made sand with rounded cubic grain shape, and its performance is comparable to natural sand.
3. Grading control
The gradation of machine-made sand is unreasonable, and the machine-made sand is “big at both ends and small in the middle”. This is mainly because the content of coarse particles above 2.36mm and fine particles below 0.15mm exceeds the standard, while the content in the middle area is relatively small. Choosing suitable sand making and screening equipment can not only effectively control the gradation of machine-made sand, but also the finished sand can meet the sand gradation requirements of Zone II.
4. Fineness modulus control
The fineness modulus of machine-made sand is too large, and there are too many coarse particles. Generally, sand with a fineness modulus of 3.1-3.5 belongs to medium-coarse sand. As long as a reasonable sand production process is adopted, the fineness modulus of the machine-made sand can be continuously adjusted, and the fineness modulus of 2.3-3.0 can be produced according to demand. of middle sand.
5. Stone powder content control
It is unavoidable to produce a certain amount of stone powder in the production process of machine-made sand. Generally, the amount of stone powder will be high. The high content of stone powder in machine-made sand will not only affect the performance of concrete mortar, but also cause waste of resources and environmental pollution. Adopting a reasonable sand making and powder content control process, on the one hand, can reduce the amount of powder in sand making, and on the other hand, the powder content of the finished machine-made sand can be adjusted and controlled at 5-15%.
6. 5 levels of broken, 2 times of plastic surgery
Firstly, the primary crushing (coarse crushing) of the parent rock is carried out by the extrusion method of the jaw crusher to reduce the diameter of the parent rock and reduce the production pressure of the impact crusher; The second crushing (intermediate crushing) is carried out to further develop the micro-cracks of the aggregate produced by the jaw crusher, and finally the aggregate is broken again from the micro-cracks to complete the second crushing and the first shaping of the aggregate; The impact crusher performs the third crushing (fine crushing) and the second shaping of the aggregate in the way of “rock hitting rock” or “rock hitting iron”.
The above are the points that need to be paid attention to to improve the quality of the sand making machine. In fact, if you want to produce high-quality machine-made sand, the key is to choose professional sand making equipment and a reasonable sand making process.
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