In the actual production and use of concrete, concrete antifreeze is a very important substance. It plays a very important role and significance in ensuring better application of concrete. It helps For the preservation and use of concrete, the rational application of antifreeze is very necessary. In the actual application of concrete antifreeze, in order to make its role better, relevant staff should master its principles and usage methods, so that the application of concrete can achieve more ideal results and provide better guarantee for better application of concrete. .
Concrete is a very important building material, so it is very necessary to ensure the normal production and application of concrete. In the practical application of concrete, it is very important to pay attention to the anti-freeze of concrete, and the application of antifreeze can achieve this goal better, which is very beneficial to the better application of concrete. In order to better apply concrete, relevant staff need to master its principles and how to use it. Only on this basis can its value be realized and effectively avoid freezing problems in concrete that affect normal use. This article briefly analyzes the principles and usage of concrete antifreeze.
01. Principle of concrete antifreeze
For concrete antifreeze, it mainly uses Based on the mechanism of concrete freezing damage, combined with relevant theories such as anti-freeze critical strength, ice crystal form transformation and optimal ice formation rate, a specific substance was successfully developed by summarizing the specific practical experience in winter engineering construction. There are four main components of concrete antifreeze, the details of which are as follows.
1.1 Early strength components in concrete antifreeze
In the actual construction process of construction projects, they are usually The concrete needs to reach a certain strength before it can continue to the next process. In the initial stage of final setting of concrete, care should be taken to prevent large vibrations in the floor due to load. The main function of the early strength component in concrete antifreeze is to accelerate the setting and hardening of concrete, so that the strength of concrete can reach the anti-freeze critical value as early as possible. On this basis, it can also accelerate the hardening speed of concrete, which can effectively change the strength of concrete due to low temperature and load. Temperature may result in slower strength growth.
1.2 Air-entraining components in concrete antifreeze
The so-called air-entraining components refer to The role of micron-level related tiny bubbles introduced into the concrete mainly includes two aspects: first, it can cut and seal the related connecting pores inside the concrete, which can reduce the crack expansion caused by frost heaving; Second, by introducing a large number of air bubbles, it can buffer the expansion and absorb the expansion stress of ice crystals, which can reduce freezing damage and thus improve the performance of retarded concrete.
1.3 Water-reducing components in concrete antifreeze
For the water-reducing components in antifreeze, the main It includes the following two functions: first, it can reduce the mixing water, so that the total amount of free water can be effectively reduced, thereby eliminating the internal factors of frost heave; second, it uses the dispersion effect of the water-reducing component to The release of wrapped water eliminates inferior blisters, promotes the transformation of coarse ice crystals into fine ice crystals, and optimizes the cement hydration environment. On this basis, the frost heave pressure can be reduced.
1.4 Antifreeze ingredients of concrete antifreeze
This ingredient is usually inorganic salts, which can reduce freezing point The freezing point of the aqueous solution is approximately minus 1.5°C. When the temperature drops to minus -1.5°C, inside the pores, the freezing point is close to the frozen side. The adjacent free water will freeze, part of the inorganic salts present inside the patient will precipitate, and the salt concentration in the remaining free water will increase; when the temperature further decreases, the water adjacent to the frozen side will Some of the free water will freeze, and the salt concentration of the remaining free water will further increase. Through the continuous continuation of this process, the lowest co-dissolution point in sodium nitrite will appear, and all free water in the hole will All will turn into ice. Therefore, the main function of the antifreeze component is to ensure that there is always a certain amount of liquid water inside the concrete during the continuous cooling process, which can also promote the continuous hydration of the cement.
02. Correct use of concrete antifreeze
2.1 Correct understanding of usage temperature
Any antifreeze that complies with the standard has a clear usage temperature. The usage temperature is often understood as the allowable temperature for concrete construction. However, more attention needs to be paid to the frost resistance of concrete. To understand the critical strength, that is to say, before the ambient temperature drops to the point where admixtures are required, the strength of the concrete should be able to reach the critical frost resistance standard. Only on this basis can the safety of the concrete be guaranteed to avoid frost damage to the concrete. In the actual application process of concrete antifreeze, otherThe lower the service temperature, the better the antifreeze effect of the antifreeze, which means that the concrete has more time to increase its strength, which makes it easier to reach the critical anti-freeze strength. As far as the current actual use of antifreeze in our country is concerned, its use temperature is usually minus 10~15℃. When the temperature further decreases, the difficulty in designing the antifreeze formula increases, and the uncertain factors also increase. Will increase. In this regard, the use temperature of antifreeze does not necessarily have to be lower than the construction environment temperature in most cases. The main thing is that the concrete should reach the critical anti-freeze strength before the temperature drops to the use temperature. .
2.2 Select the covering insulation method
For the comprehensive thermal storage method, the basic approach is to Add antifreeze to cover, and heat water and sand if necessary. For covering, its main function is to further extend the residence time of cement hydration heat and raw material heating heat inside the concrete, so that the positive temperature hydration time of cement can be extended, which is of great significance. On the basis that thermal insulation can be better achieved, the time for the concrete temperature to drop to the point where admixtures are required will be extended, giving the concrete more time to reach critical frost resistance strength. In order to achieve this effect better, the type and thickness of the covering material should be determined through thermal calculations in combination with various factors.
2.3 Proper construction organization
For concrete antifreeze, in order to obtain the ideal use effect , stirring and vibrating should be carried out better. Extending the stirring time by 30 minutes is mainly to promote more complete mixing of the admixtures. If the admixtures are not stirred evenly, certain accidents may occur. For admixtures, there are problems with optimal mixing time and vibration time. Excessive mixing and vibration will often lead to a reduction in air entrainment. If stirring and vibration are insufficient, uneven distribution of air bubbles will occur, and even Coarse and inferior bubbles are produced, which will have a negative impact on antifreeze. In addition, the transportation distance should be shortened as much as possible. An insulating shed can be installed at the mixing station, an insulating cover can be set outside the conveying pipe, the rack truck can be covered with an insulating cover, and each process can be tightly connected. These measures are all to enable slow concrete The mold entry temperature can be increased, which can extend the positive temperature curing time and enable it to reach critical strength as early as possible.
2.4 Scientific and reasonable thermal calculations
In terms of thermal calculations, it is mainly based on Wu Zhendong Formula, this formula has many uses, the main function is to conduct verification calculations, its specific points include the following aspects: first, calculate the concrete molding temperature based on the raw material and ambient temperature; second, calculate the concrete molding temperature The specific time required for the temperature of the mold to be reduced to the temperature specified by the antifreeze; third, calculate the relevant strength that the concrete can achieve within the above curing time according to the proficiency formula; fourth, compare this strength with the critical anti-freeze strength Compare and determine the construction plan on this basis; fifth, leave the test block under the same conditions during the construction process, and test its actual strength 1 day before the ambient temperature drops to the temperature of using antifreeze to determine whether it meets the requirements. Frost resistance critical strength.
03. Conclusion
In the actual application process of concrete, preventing concrete from freezing is an important task , is also the premise and basis for the normal application of concrete, and the application of concrete antifreeze can make this goal better achieved. In the actual application process of concrete antifreeze, relevant personnel should choose the correct usage method to utilize the antifreeze based on mastering its principles, so that the role of the antifreeze can be better exerted and provide guarantee for better application of concrete.
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