Xie Zili said: "Compared with ordinary concrete, machine-made sand concrete has better water retention, strong cohesion and less water secretion; The compressive strength and tensile strength of machine-made sand concrete are higher than those of ordinary concrete of the same age and grade, and the frost resistance and impermeability are better than those of ordinary concrete; The stone powder content is in the range of 10%, the higher the content, the higher the strength of the concrete, and the better the frost resistance and impermeability; The shrinkage deformation, carbonization and steel corrosion properties of machine-made sand concrete are comparable to those of ordinary concrete. The combined effect of the filling effect, crystal nucleation effect, activity effect, water absorption effect and morphological effect of stone powder in www.biquge.info machine-made sand has contributed to the improvement of the performance of machine-made sand concrete. ”

In fact, the earliest application of manufactured sand is not a commercial concrete mixing plant, but an on-site construction unit.

Machine-made sand refers to particles of different sizes that are broken by rock and screened with a particle size of less than 5mm. As early as the early 80s, the residential construction in some areas of the country entered a climax, and the natural pebbles could not meet the needs of the production of housing components, so the stone crushing plant came into being. At that time, stone chips were discarded as a large number of wastes, and some prefabricated component factories transported back stone chips for the production of small components, because there was no natural river sand in these areas, only natural extra-fine sand, and extra-fine sand was prepared separately for concrete, and there were many problems, so stone chips were applied, mainly replacing extra-fine sand, and the test found that the strength of the specimen was greatly improved after the stone chips replaced the extra-fine sand. After that, the stone chips were gradually expanded to be used in prestressed hollow slabs, and it was found that not only the concrete could save cement, but also the quality of the components was improved.

Of course, Li Ruoyu also remembers that the unit that officially developed and applied machine-made sand and carried out systematic test research was the Chengdu-Chongqing Expressway Headquarters of the Fifth Railway Bureau. In May 1990, the construction of the Liangshan Tunnel of the Chengdu-Chongqing Expressway began, in order to reduce the cost of the project and reduce the pressure of purchasing natural medium sand from other places, the Chengdu-Chongqing Expressway Headquarters decided to use machine-made sand in ordinary concrete, pumped concrete, waterproof concrete, sprayed anchor support and masonry mortar. To this end, four professional sand and gravel production lines have been built nearby, and local materials have been taken, and the limestone excavated by the project has been used as raw materials, with a total of about 100,000 tons of machine-made sand and more than 100,000 square meters of concrete poured. A large number of data prove that the application of manufactured sand in highway engineering is successful. Thus, it has laid the foundation for the development and application of manufactured sand.

Of course, manufactured sand has not been applied to commercial concrete until now. So Li Ruoyu is going to be this crab eater. Because it will not take a few years, the standard of machine-made sand concrete will be introduced, if Zhongsheng Concrete Company can be the first to apply and participate in the compilation of standards, it will be very beneficial to the company's future development.

As a traveler, Li Ruoyu knows that China's professional machine-made sand production plants have experienced mistakes and lessons of varying degrees in the construction process, and even paid a heavy price. There are lessons and experiences for him, so it is a good reference for him.

Li Ruoyu smiled: "Therefore, we have to use machine-made sand, use it in large quantities, and control the production of machine-made sand in our own hands, so that we will not be stuck." The process design of the manufactured sand production line is the most critical link to determine the investment scale, production efficiency, product cost and operation reliability. There have long been precedents for highway construction and application in southwest China, but there are some problems in the process design of the machine-made sand production line built in the early stage, and it has to be transformed after it is put into operation. For example, the process design is not reasonable, the crushing equipment is not properly selected or does not match the process flow, the screening system is not matched, the transmission system is too complex, and the equipment maintenance is inconvenient. The design and production scale of individual enterprises is too large, resulting in excessive investment and low equipment utilization, which directly leads to high production costs in the later stage. ”

"Another is that the selection and reliability of the sand making machine is the key to ensuring the quality of the machine-made sand. The crushing equipment suitable for sand making mainly includes rod mill type, hammer type, impact type, rotary disc type, vertical impact crusher, etc. These sand making machines have their own advantages and disadvantages. After we have acquired the sand and gravel plant, we must carefully investigate its specifications and power when selecting the equipment, and must adapt to the objective environment of the production line, and pay attention to matching the feed particle size, production capacity and efficiency. Improper equipment selection often causes frequent failures, low efficiency, excessive energy consumption and other problems, which brings difficulties and troubles to normal production in the future. ”

Li Ruoyu said solemnly: "There is also a process design to adapt to local conditions, as much as possible to make use of the terrain height difference, professional machine-made sand production line generally adopts two-stage or three-stage crushing, to focus on reducing the operating power and cost of the equipment." Raw material crushing, sand making, screening equipment must be matched, and convenient maintenance should be considered. The wet process is a better method for manufactured sand production, which can effectively prevent dust pollution, ensure product quality, improve production efficiency, especially not affected by rainy weather, and can improve equipment utilization. Priority is given to the wet sand making process in the process design of the new plant. ”

Xie Zili continued: "That's right, the quality of the mine's parent rock is one of the important factors that determine the quality of machine-made sand, and the strength of the limestone matrix should not be less than 80 megapascals. We must first do a good job in the exploration of mine resources, and the strength of the mine parent rock should not be less than 80 megapascals. In order to avoid the impact of poor ore quality and high mining costs on the company, we must not want mines with thick overburden layer, more mud in the interlayer, lower strength of the parent rock, large dolomite content, and rock layered into flakes. Of course, pebbles can also produce machine-made sand, and the strength is relatively high, so we can run two production lines in parallel. ”

Li Ruoyu said: "Mr. Xie is very correct. Pebble manufactured sand can also be used in concrete production, which is stronger, but the process equipment requirements are higher. The production process of manufactured sand will inevitably bring dust pollution and damage to the existing vegetation, we must pay great attention to environmental protection issues, and must comply with the relevant policies and regulations of countries and regions. Okay, this time to acquire the sand and gravel plant, Mr. Xie, Manager Qian, Manager Zhou, and Manager Wang of the equipment department will go with me, let's go now. ”

Speaking of this, Li Ruoyu looked at Bai Yurou again, and said softly: "Sister Rou, this time I went to Zhouzhuang, the distance is relatively far, you won't go, just preside over the overall situation in the company, do you think about it?" ”

Seeing that Li Ruoyu cared about her so much, Bai Yurou was also moved in her heart, thinking that he had not forgotten himself after all, so she nodded and said, "Okay, I'll wait for your good news." ”

Indeed, Bai Yurou is not suitable to go, because she still needs to nurse the child now! You can't run that far with a baby.

Of course, Li Ruoyu didn't say it explicitly, because many people in the company didn't know that Bai Yurou gave birth to his child. It is impossible to make this matter public, it can only be a secret. (To be continued.) )