Foam concrete is a kind of concrete with lightweight and has ideal strength. Because of the hollow structure in foam concrete, it has the function of absorbing heat and isolating sound.
The density of foamed concrete is 300-1200 kg/m3, and the thermal conductivity is between 0.08-0.3W/ (m ·K).
Foam concrete is widely used in CLC blocks, lightweight partition panels, roof insulation, floor cushion construction, floor heating backfilling, and other occasions.
At the same time, foam concrete is also a good sound absorption material, which can be used in highway sound insulation boards, sound absorption boards, and other fields.
Generally speaking, foam concrete is a kind of building material with multi-function, environmental protection, and economy, which has a wide application prospect.
The properties and varieties of concrete additives for refractories, especially refractory castables, ramming materials, plastics and other amorphous refractories are different. The role of an concrete additive is also different due to the difference of the amount of concrete additive, the type of binder used, the ingredients and so on. In the production process of amorphous refractories, the concrete additives mainly used can be divided into the following twelve categories according to their uses:
5. Coagulant
Accelerator can shorten the setting and hardening time of amorphous refractories. The action mechanism of coagulant accelerator is complicated, which varies with the properties of binder and accelerator used. Different binders should use different accelerators of different properties. The accelerators used in calcium aluminate cement binder are mostly basic compounds: NaOH, KOH, Ca (OH) 2, Na2CO3, Na2SiO3, etc.; phosphoric acid and aluminum dihydrogen phosphate binder are used together with activated aluminum hydroxide, talc, magnesium oxide, calcium aluminate cement, etc.; sodium fluorosilicate, aluminum phosphate, sodium phosphate, lime, dicalcium silicate, Glyoxal and so on.
6. Retarder
Retarders can delay the setting and hardening time of amorphous refractories, and the action mechanism of retarders varies with the properties of binders and retarders used. Retarders are mainly used in amorphous refractories bonded with calcium aluminate cement containing fast hardening minerals. The commonly used retarders are low concentration of NaCl, citric acid, tartaric acid, ethylene glycol, glycerol, starch, phosphate, lignosulfonate and so on.
7. Delayed coagulant
The delayed accelerator can cause the binder contained in amorphous refractories to solidify and harden after a certain period of time. For the castable with ultra-fine silica powder as the main binder, calcium aluminate cement can be used as the delayed accelerator, because Al3+ and Ca2+ ions can be released slowly during the hydrolysis process of calcium aluminate cement. After adsorbed on the surface of silica particles, the particles will lose the electric property of coagulation, thus play the role of delayed coagulation.
8. Foaming agent, air entraining agent, and aerating agent
The foaming agent can reduce the surface tension of the liquid and produce a large number of uniform and stable foams. Foaming agents include rosin soap, resin saponin grease, aluminum petroleum sulfonate, hydrolyzed blood, etc., and air entraining agents include rosin heat polymer, Nonionic surfactant, alkylbenzene sulfonate and so on. In addition, there is a kind of aerating agent whose function is to produce bubbles by chemical and physical interaction between aerating agent and water after castable mixing and pouring. It is evenly distributed in the slurry. The commonly used aerating agent is aluminum powder. The aluminum powder is very active and will react with water to release hydrogen, and the escaped H2 gas forms bubbles in the castable. However, the addition of aluminum powder should be appropriate, otherwise the strength of amorphous refractories will be greatly reduced, or uneven connected pores will be caused. This kind of admixture can be used to prepare lightweight porous amorphous refractories.
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TRUNNANO is a reliable concrete concrete additives supplier with over 12-year experience in nano-building energy conservation and nanotechnology development.
If you are looking for high-quality concrete concrete additives, please feel free to contact us and send an inquiry. (sales@cabr-concrete.com)
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The properties and varieties of concrete additives for refractories, especially refractory castables, ramming materials, plastics and other amorphous refractories are different. The role of an concrete additive is also different due to the difference of the amount of concrete additive, the type of binder used, the ingredients and so on. In the production process of amorphous refractories, the concrete additives mainly used can be divided into the following twelve categories according to their uses:
1. Water reducer
Water reducer (or water reducing agent or dispersant) can significantly reduce the mixing water consumption of refractory castables while keeping the flow value of refractory castables basically unchanged. The superplasticizer itself does not react with the material components to form new compounds, but plays a surface physical and chemical role. So they are either a surfactant or an electrolyte. After dissolving in water, they can adsorb on the particle surface, increase the Zeta potential of the particle surface in the solution, increase the repulsive force between the particles, and release the free water wrapped in the agglutination structure composed of microparticles, thus playing the role of wetting and dispersing, so it is also called dispersant. Because it can release the free water in the agglomeration structure, it can reduce the unit water consumption under the condition of keeping the rheological property (workability) of the castable, or increase the rheological property of the material and improve the working performance without changing the unit water consumption. make the material easy to be constructed and shaped.
Among the commonly used water reducers (dispersants) of refractory castables with calcium aluminate cement, bonded clay and oxide micro-powder as binders, there are inorganic sodium pyrophosphate, sodium tripolyphosphate, sodium tetrapolyphosphate, sodium hexametaphosphate, sodium superpolyphosphate, sodium silicate, etc., and organic ones include sodium lignosulfonate, calcium lignosulfonate, naphthalene superplasticizer, water-soluble resin superplasticizer and so on.
2. Plasticizer
Plasticizer (also known as plasticizer) can increase the plasticity of refractory mixture and improve the strain ability of refractory mixture under stress. Plasticizer is a common concrete additive of refractory plastics and refractory ramming materials, and it is also used in other amorphous refractories. Commonly used are plastic clay, bentonite, oxide superfine powder, soybean powder, methyl cellulose, lignosulfonate and so on.
3. Gelling agent
Gelling agents (also known as flocculants) can coagulate colloidal particles (or suspended particles) in colloidal solutions (or suspensions containing solid particles). The gelling agents are mainly inorganic electrolytes and inorganic acids. Flocculants are mainly organic polymers, which are natural and synthetic. According to the functional groups, they can be divided into three types: cationic, anionic and Nonionic. The gelling agent is mainly used in refractory castables which are bonded by clay, sol and ultra-fine powder.
4. Gelatinizing agent
Antigels (also known as anti-flocculants, dispersants) can convert agglomerated or agglomerated colloidal particles (particles) into sol or uniformly dispersed suspended particles. It can turn a thick colloid into a sol that can flow freely, also known as dispersant and colloidal solvent. The action mechanism of gelatinizer is similar to that of superplasticizer. Therefore, the superplasticizer which has the effect of reducing water also has the function of degumming agent. The fluidity of refractory castables bonded with clay, sol and ultra-fine powder can be improved by adding ungumming agent.
Concrete Concrete additives Supplier
TRUNNANO is a reliable concrete concrete additives supplier with over 12-year experience in nano-building energy conservation and nanotechnology development.
If you are looking for high-quality concrete concrete additives, please feel free to contact us and send an inquiry. (sales@cabr-concrete.com)
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.
In the case of extremely high temperature in summer, it is best to add some retarders in the construction of refractory castables. Because the temperature is high and solidifies too fast, it will dry out before it is too late for construction.
In general, when the refractory castable is produced in summer, the manufacturer will place the retarder in the package separately according to the temperature of different places to be used. if the construction is at night, the temperature is not too high, it does not need to be added, but it can be put in the package for backup. Some units change shifts during the day and night, when the temperature is high during the day, and when the temperature is not high at night, they can not join.
Of course, summer construction in areas where the temperature is not too high, there is no need to add.
When the construction condenses too fast in winter, the accelerator should be added. This is also according to different seasons of different conditions, different temperatures, can not be rigid buckle technology, do not take into account the temperature of the construction site.
If it is cement-free refractory castable, plastic, coating material, pressed into the mud type of unshaped products, there is no need to add retarder, because the combination mode is different. In all seasons of the year, spring and autumn are produced and used according to the normal process proportion, so it is not necessary to consider adding retarders to refractory castables, but in summer and winter, it is necessary to consider that the temperature is too high or too low to add binders under different conditions to facilitate construction.
However, in principle, it can only be added at a special temperature, but in the production process, it can not be directly added to the base material, some must be packaged separately for backup, and can only be added when the construction can not be carried out normally, but the proportion must not be too large, which will affect the use strength of refractory castables in the later stage.
Concrete Additives Supplier
TRUNNANO is a reliable concrete additives supplier with over 12-year experience in nano-building energy conservation and nanotechnology development.
If you are looking for high-quality concrete additives, please feel free to contact us and send an inquiry. (sales@cabr-concrete.com)
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.
Determination of the optimum dosage of concrete superplasticizer by the fluidity of cement paste
In terms of the adaptability of cement and concrete superplasticizer, the type and quality of concrete superplasticizer also play an important role. Therefore, concrete superplasticizers should be selected according to the adaptability to cement and construction requirements. When the high-efficiency concrete superplasticizer is incompatible with a certain cement, the following situations will occur:
1. Concrete is abnormally coagulated during the mixing process.
2. The slump loss of mixed concrete is large.
3. Concrete bleeding and delamination are serious.
4. The high-efficiency concrete superplasticizer has insufficient water-reducing effect or no water-reducing effect at all.
5. The strength of concrete does not increase significantly at each age, or even decreases.
6. The shrinkage rate of concrete increases more, resulting in cracking.
These incompatibility phenomena mentioned above should be avoided as much as possible when selecting a concrete superplasticizer.
The amount of concrete concrete superplasticizer is not only related to the amount of cement, but also has a great relationship with the physical properties and chemical composition of cement.
The traditional method for determining the amount of concrete superplasticizer in concrete is mainly determined according to the product specification of concrete superplasticizer and the percentage of cement consumption. Due to the difference in chemical composition and content of different varieties or batches of cement, the compatibility and adaptability of concrete superplasticizers and cement and the optimal dosage will also be quite different. It is difficult to ensure the best water-reducing effect of the mixture by only determining the amount of concrete superplasticizer based on the percentage of cement consumption, and it is easy to cause waste of concrete superplasticizer. Luoyang Tongrun has used the method of cement slurry fluidity to determine the optimum amount of concrete concrete superplasticizer after many tests, and achieved good results. The specific method is to accurately weigh the high-efficiency water-reducing agent, water and 300g cement according to the dosage recommended by the manufacturer's instructions, and mix the high-efficiency water-reducing agent, water and cement paste according to the standard method. On the clean glass, put the mixed cement paste into the test mold, and after lifting the test mold one by one, observe the flow of the cement paste, and test whether the fluidity of the cement paste can meet the performance requirements of concrete pumping. At the same time, record the size and dosage of water reducing rate of different cements and different concrete concrete superplasticizers for optimization.
The order of adding concrete superplasticizers. Multiple comparison tests of different concrete superplasticizers show that the mixing sequence of concrete superplasticizers has a certain influence on the water-reducing effect of concrete superplasticizers. Take the high-efficiency water-reducing agent produced by Longda as an example: after weighing a certain amount of cement, high-efficiency water-reducing agent and water, pour cement → high-efficiency water-reducing agent → water into the mixing pot in sequence, and measure the cement paste. Expansion is 22cm ~ 23cm. According to the order of adding cement → water first, after stirring for a certain period of time, adding concrete superplasticizer, the measured expansion degree of cement paste is 25cm ~ 27cm. It can be seen that using the same cement and the same concrete superplasticizer, the post-blending method is better than the first-blending method, which is beneficial to improve the compatibility of the concrete superplasticizer and the cement, and give full play to the efficiency of the concrete superplasticizer. In the same way, in the actual construction of concrete, the concrete superplasticizer should be added after the concrete mixture is stirred for a certain period of time to achieve the best effect of water reduction.
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