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 foaming agent.
How does cement foaming agent affect the performance of foamed concrete?
Cement foaming agent is the key material in the production of foamed concrete. Whether it can produce foamed concrete with suitable density depends on the selection of a suitable cement foaming agent. There are many types of cement foaming agents on the market now, and the prices are also very different. Many people choose the foaming agent blindly or choose whichever is cheaper. In fact, the cost of cement foaming agent in foamed concrete is relatively low. If we choose cement foaming agent based on price alone, I think it is not advisable.
At present, the cement foaming agent on the market is generally divided into synthetic cement foaming agent, animal and vegetable protein cement foaming agent, composite cement foaming agent, and rosin soap cement foaming agent. Each of these types of blowing agents has advantages and disadvantages.
The advantage of animal protein cement foaming agent is that it has better foam stability and closed cell rate. The foaming power and stability of vegetable-based cement foaming agents are relatively balanced.
In the concept of many people, the cement foaming agent is only foaming and densification. This idea is very one-sided. Cement foaming agent is actually related to the strength, thermal conductivity, setting speed, water absorption, pouring height and other properties of foamed concrete products. Therefore, the selection of cement foaming agent should not only look at its price, but should look at the overall cost. The cost of cement in foamed concrete is the main cost. Reducing the cost of cement is the key to reducing the cost of foamed concrete. How to reduce the cost of cement? It can reduce the amount of cement by increasing the strength. The strength of foamed concrete with the same density has been improved. If the strength remains unchanged, the amount of cement can be reduced and the density can be reduced to achieve the original strength. For example, the strength of the original 400-density foam concrete is 0.6mpa, but by increasing the strength, it can reach 0.6mpa with 350. This saves 50 kilograms of cement, the strength is achieved, and the thermal insulation performance is also improved. But one of the keys is to choose a good cement foaming agent.
The following is a brief introduction to the effect of cement foaming agent on the performance of foamed concrete:
1. Strength
The strength of foamed concrete is a key indicator. Foamed concrete is an artificial stone that has been foamed. The density is low, and the strength will naturally decrease with it, and the strength will decrease more when the density is small. How to make the strength of foam concrete better has become a key factor in improving the performance of foam concrete. A good choice of cement foaming agent can effectively improve the strength of foamed concrete. A good cement foaming agent can form bright and closed pores in the foamed concrete, which greatly improves the density of the foam wall and thus improves the strength. A good cement foaming agent can be used at a low water-cement ratio, and the lower the water-cement ratio, the higher the strength. At present, many cement foaming agents on the market can only be used at high water-cement ratios, which is the main reason why many construction teams use high water-cement ratios for construction. ", at the expense of the strength of foam concrete. The compatibility of cement foaming agent and cement also affects its strength. If the cement foaming agent does not match the cement, the more common problem is that the foaming agent becomes the isolation layer of the cement, forming a "false coagulation" phenomenon, which is actually not solidified.
2. Water absorption rate
Many foamed concrete products on the market now have a very high water absorption rate, some as high as 50%. The reason is that the closed cell rate of foamed concrete is low, and the foam is broken to form through-holes due to foaming and poor stability of the foam of the cement foaming agent. This is all caused by the low closed cell rate of the cement foaming agent, so a good cement foaming agent can make the water absorption rate of the foamed concrete products low.
3. Pouring height
The pouring height of foam concrete is directly related to the foam stability of the cement foaming agent. The higher the foam stability of the cement foaming agent, the higher the pouring height, and vice versa. The higher the pouring height, the greater the pressure of the slurry on the foam, and the foam will collapse if the stability is poor.
4 density
The key to controlling the density of foamed concrete is the amount of foam added, so the direct factor that affects the density is the cement foaming agent. The more stable the foam of the cement foaming agent is, the easier the density is to control, and the more foamed concrete with low density can be made. On the contrary, the stability of the cement foaming agent is not good, it is possible to design a density of 400, and pour it out to 500 kg. It is also possible that the upper and lower densities are not the same, that is, the density is not uniform. Such a problem is more obvious in the wall pouring.
4. Thermal conductivity
The direct influence factor of thermal conductivity is the density of foamed concrete, and the key factor of density control is the cement foaming agent. Correct a misunderstanding in the industry: it is generally believed that the thermal conductivity is directly related to the closed cell ratio, but in fact, according to our testing of foam concrete test blocks with different closed cell ratios with a density of 200 kg/m3, we found that the high closed cell ratio was closely related to the closed cell ratio. The porosity is low compared to the thermal conductivity of 0.059 with no significant difference.
To sum up, the cement foaming agent affects the performance indicators such as strength, water absorption, pouring height, density and thermal conductivity of foamed concrete.
TRUNNANO is a concrete additives supplier with over 12 years experience in nano-building energy conservation and nanotechnology development. We accept payment via Credit Card, T/T, West Union and Paypal. Trunnano will ship the goods to customers overseas through FedEx, DHL, by air, or by sea.
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At present, international supply chains were shocked, and logistics and transportation efficiency decreases. Geopolitical conflicts further aggravate uncertainties about the European and American economic recovery and the global commodity supply. For this reason, I assume the price of the foaming agent would not decrease significantly in the short term.
