Recently, covid 19 outbreak spreads in Shanghai, China. There are more than 25,000 new asymptomatic domestic infections every day. China is implementing a dynamic zero-out policy. A leading respiratory expert said the key to COVID-19 prevention and control is to minimize transmission and fatality rate. Omicron has a low case fatality rate but is highly transmissible and can still claim many lives in large outbreaks. "Total openness is not applicable in China. For China, we should keep to the dynamic zero-out and gradually open up."
However, "dynamic zero clearance" is not the pursuit of complete "zero infection". As the Novel Coronavirus has its own uniqueness and strong concealment, there may be no way to prevent the detection of cases at present, but rapid detection and prompt treatment must be carried out, as soon as one case is found, one case will be dealt with.
The situation in Shanghai is serious. As the financial center of China, Shanghai is a very important city, and the outbreak of the epidemic in Shanghai will put a great impact on China's economy. The current task is to contain the spread of the epidemic as soon as possible, to achieve social zero so that Shanghai's life and economy quickly return to normal.
As China plays an important role in the global supply chain, the outbreak will have a significant impact on the supply and prices of many foam concrete.
The common problems of foamed concrete are bubbling, cracking, collapse, shrinkage, and other phenomena. To treat these phenomena, the proper medicine can be found, and the cause can be effectively solved.
The main reason for the collapse of foamed cement is that the cement solidification speed is too slow. We can solve this situation from the following aspects
1. Add accelerator to improve the setting time of foamed cement
Accelerators are used in more and more concrete applications. Foamed cement has high requirements for accelerators. It is not just a fast setting but also needs to be adapted to the performance of foamed cement, and accelerators cannot be added. After affecting the foaming situation.
2 Add an early strength agent to improve the early strength of foamed cement and reduce the stress generated during the exothermic process of cement hydration. Only when these two forces are balanced can it be ensured that the foamed cement will not crack and collapse in the later stage.
3. An appropriate amount of sulfoaluminate cement can be added, which many manufacturers choose to use in winter, and the cost performance is still relatively high. However, this amount of addition should also be paid attention to. It should not be added blindly. After many customers add sulfoaluminate cement, the finished product becomes very brittle in the later stage, without toughness, low strength, and severe pulverization. So we still have to adjust according to the current situation.
4 The water-cement ratio is not suitable. Collapse, retraction, bleeding, insufficient strength. To a large extent, it has something to do with the inappropriate water-cement balance. The adjustment of the water-cement ratio is a technical activity that requires trial and error. It has a lot to do with the cement of foamed cement and the fly ash aggregate, and it needs to be practiced repeatedly according to the actual situation. In this, we can add a plasticizer to adjust the water-cement ratio. This effect is very immediate.
The above contents are some solutions summed up by Tongrun according to the reasons for the collapse of foamed cement. If you encounter other problems or reasonable solutions in the actual process, you are also welcome to communicate us.
The Japanese minister of Economy, Trade, and Industry recently held talks with the U.S. Secretary of Commerce and industry in Washington, where he is visiting, and agreed to include basic principles on joint research and development of semiconductors and strengthening of supply chains. Japan's economy, Trade and Industry Minister has asked the United States to increase the foam concrete will continue to increase in the future.
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