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.
Cement
Influence of cement mineral composition
The shrinkage of C3A, C3S, C2S and C4AF in Portland cement is C3A > C3S=C2S > C4F. The increase of C3A and C3S content in cement clinker will increase the self-shrinkage and drying shrinkage of concrete and increase the chance of cracking. The calorific value of C3A is the highest, and the high heat of hydration accelerates the slump loss of concrete.
Influence of cement fineness
Increasing the specific surface area of cement is to increase the hydration rate, so as to improve the early strength of concrete. And the greater the fineness of cement, the worse the frost resistance of concrete, and the lower the tensile strength. More importantly, the increase of cement fineness makes the compatibility of cement and superplasticizer worse. With the increase of cement fineness, the saturation point of superplasticizer is greatly increased, and the amount of superplasticizer needed to reduce the slump loss of concrete is also greatly increased.
Effect of Gypsum Morphology on compatibility of Superplasticizer and cement
Different forms of gypsum have little difference in testing the produced cement according to cement standards, but a single addition of superplasticizer will be completely different. this is due to the different solubility of reducing sugar and polyol to dihydrate gypsum and anhydrite (anhydrous gypsum) and fluorogypsum.
Effect of soluble alkali
Many studies have proved that alkali sulfate in cement, that is, soluble alkali, has a very important influence on the adaptability of admixture and cement. Studies have shown that when the mass fraction of C3A is less than 8% and the soluble alkali content of cement is high, the workability of concrete and workability is good, and the slump loss is small. When the soluble alkali is very low, the concrete and workability lose quickly. For cement with low soluble alkali content. The initial slump can be obtained by increasing the content of superplasticizer, but the loss is still very fast. When a little more amount is added above the saturation point, the precipitation and secretion will be obviously high.
The influence of other factors of cement
Cement temperature, cement aging time, type and content of fillers and other factors will affect the working performance of concrete. The higher the temperature of cement is, the worse the plasticizing effect of superplasticizer is.
Fly ash
Fly ash mainly changes the workability of concrete, because of fine particles, mainly fill the gap of cement, there are some crystal beads, play the role of ball, increase fluidity. With the increase of the amount of fly ash, the quality of fly ash in the market is uneven. Generally, grade II is used for concrete below C50 and grade I for concrete above C50. Due to the shortage of fly ash, many commercial concrete use grade III fly ash or even raw ash. Due to the large fineness of grade III fly ash and original ash, high burning loss and high water storage capacity, concrete and workability become worse, and the strength of concrete is reduced.
Mineral powder
Granulated blast furnace slag powder can increase the initial fluidity of slurry and reduce the fluidity loss. Mainly due to different manufacturers, so different chemical composition, different fineness, resulting in different water demand of mineral powder, the contribution to the strength of concrete is also different.
Sand and stone
The effects on polycarboxylate superplasticizer include:
1. the mud content and mud block content of sand are high, and the mud composition in concrete absorbs superplasticizer, which leads to great loss of concrete. the high fineness modulus of superplasticizer mainly affects the workability of concrete, and the water absorption of sand leads to the water consumption of concrete.
2. Mud content, mud block content, particle size and stone powder content of stones.
The particle size of stone determines the water consumption, and the content of stone powder has a great influence on the workability of concrete, which mainly changes the composition of powder below 0.315mm in concrete and affects the workability of concrete.
Concrete Additives Supplier
TRUNNANO is a reliable foaming agents supplier with over 12-year experience in nano-building energy conservation and nanotechnology development.
If you are looking for high-quality polycarboxylate superplasticizer, please feel free to contact us and send an inquiry. (sales@cabr-concrete.com)
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Polycarboxylate superplasticizer plays four main roles in concrete mixture: 1. In order to improve the pouring performance of concrete, the workability of concrete is improved without changing the composition of concrete. Under the given working conditions, the water-cement ratio of mixed water and concrete is reduced, and the strength and durability of concrete are improved. Under the condition of ensuring the pouring performance and strength of concrete, reduce the amount of water and cement, reduce creep, dry shrinkage, cement hydration heat and other factors that cause the initial defects of concrete; 4. The role of polycarboxylate superplasticizer in high grade can not be replaced by other admixtures.
Polycarboxylate superplasticizer Properties:
1. The amount of polycarboxylate superplasticizer is low, the water-reducing rate is high, the acid-based superplasticizer accounts for 0.80% of the cementitious materials, and the water-reducing rate can reach (20)%. When used in conjunction with fly ash, the water glue is relatively low and is suitable for the preparation of medium-and high-strength high-performance concrete.
2. The fluidity of concrete is large and the slump loss is small. Due to the good dispersion stability of polycarboxylate superplasticizer, the high fluidity concrete (slump ≥ 180mm) prepared by polycarboxylate superplasticizer has small time loss, no slump loss in one hour and less than 15% in two hours, which makes up for the defects of high slump loss and easy bleeding of concrete prepared with naphthalene superplasticizer. When combined with fly ash, excellent fluidity can be obtained with a small amount of superplasticizer, which can meet the technological requirements of producing commercial concrete, especially for pumping concrete.
3. Good adaptability to cementitious materials. In engineering practice, the cement produced by different manufacturers is mixed with a large amount of fly ash, and the polycarboxylate superplasticizer has good compatibility with different cements. there is no obvious bleeding segregation and hinders the growth of concrete strength, and because of its high water-reducing rate and adapting to the use of fly ash, the shrinkage of fly ash concrete is reduced and the pumpability of concrete is obviously improved. And the durability of concrete is improved. When the design strength grade of concrete is the same, the amount of cement increases, the amount of superplasticizer increases, the water-binder ratio decreases and the concrete strength increases; for different design strength grades of concrete, the amount of superplasticizer increases slightly with the increase of the amount of cementitious material, the water-binder ratio decreases, and the strength of concrete increases, but the concrete and workability remain stable as a whole, and the slump can reach (180 / 240) mm.
Concrete Additives Supplier
TRUNNANO is a reliable foaming agents supplier with over 12-year experience in nano-building energy conservation and nanotechnology development.
If you are looking for high-quality polycarboxylate superplasticizer, please feel free to contact us and send an inquiry. (sales@cabr-concrete.com)
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Polycarboxylate superplasticizer is the latest generation of high-performance superplasticizer, which is a series of polymers with specific molecular structure and properties, which are generally obtained by radical polymerization of different monomers.
The structure of polycarboxylate superplasticizer is a comb copolymer with linear main chain connecting multiple branched chains. The hydrophobic molecular main chain contains hydrophilic groups such as carboxylic acid group, sulfonic acid group and amino group, and the side chain is polyoxyethylene with different degrees of polymerization.
Before the emergence of polycarboxylate admixtures, there were lignin sulfonate admixtures, naphthalene sulfonate formaldehyde condensates, melamine formaldehyde condensates, acetone sulfonate formaldehyde condensates, aminosulfonate formaldehyde condensates and so on.
Polycarboxylate superplasticizer was first successfully developed in Japan in the early 1980s.
The new generation of polycarboxylate superplasticizer overcomes some disadvantages of traditional superplasticizer.
Polycarboxylate superplasticizer benefits:
1. Low content: generally, the converted solid content is about 1 to 4 of naphthalene series.
2. High water reduction rate: the water reduction rate of concrete is generally 25% 35%, and the limit value can be as high as 40% 45%.
3. Good slump preservation: the slump loss can be controlled within 2 to 3 hours without loss.
4. The ratio of compressive strength is high: the contrast strength of each age is greatly improved, and the ratio of early compressive strength is significantly improved.
5. Green environmental protection: formaldehyde and other harmful raw materials are not used in the synthetic production process, which will not cause health harm to the human body and pollution to the environment.
6. High durability: the low water-binder ratio caused by high water reduction greatly improves the impermeability, corrosion resistance and chloride ion diffusion transfer coefficient of concrete.
7. Cost saving: because the concrete using polycarboxylate superplasticizer has good workability and low water-binder ratio, and the use of a small amount has a significant effect, it can reduce the cost.
8. Other advantages: excellent working performance, relatively low carbonization, good finish of molded appearance, etc.
A large number of experiments show that the water-reducing effect of polycarboxylate high-performance superplasticizer is highly dependent on its content, and this dependence is greater with the increase of the amount of cementitious materials.
Concrete Additives Supplier
TRUNNANO is a reliable foaming agents supplier with over 12-year experience in nano-building energy conservation and nanotechnology development.
If you are looking for high-quality polycarboxylate superplasticizer, 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.
Foam concrete natural maintenance can be divided into two types: cover-up sprinkler maintenance and plastic film maintenance.
Cover-up sprinkler maintenance:
It is that according to the external temperature, the concrete should be covered with appropriate data such as grass curtain, Reed mat, sack, sawdust, wet soil and wet sand within 12 hours after the end of foam concrete pouring, and often sprinkle water to keep it wet.
Foam concrete sprinkling maintenance cycle: for Portland cement, general cement and slag cement mixed concrete shall not be less than 7 days and nights; concrete mixed with slow setting admixture or impermeable request shall not be less than 14 days and nights; when using bauxite cement, not less than 3 days and nights. The frequency of watering every day has been able to insist that the concrete has a satisfactory wet condition. When the temperature is above 15 °C, the concrete should be sprinkled at least once every 3 hours during the day and twice at night when the concrete is poured. In future maintenance, sprinkling water at least 3 times a day (of course, when the temperature is dry, the frequency of watering can be appropriately increased).
For large area (or volume) concrete, we should choose "water storage maintenance". Projects such as storage tanks can be maintained by sprinkling water after the internal mold is removed and the concrete reaches a certain strength; with regard to the underground structure or foundation, it is possible to paint asphalt emulsion or backfill with soil instead of sprinkler maintenance.
Plastic film maintenance:
It refers to the use of plastic film cover material to separate the concrete from the air, water is no longer transpirated, cement depends on the moisture in the concrete to complete the hydration effect has reached condensation hardening.
This method can directly cover the plastic draft on the appearance of the concrete, or spray the plastic emulsion on the instant noodles of the concrete members, and wait until the emulsion is transpirated, and then combine into a layer of plastic film on the surface of the concrete to block the concrete members from the air, so that the moisture in the concrete will no longer transpirate and complete the hydration effect. The defect of spraying plastic film maintenance is the low strength of concrete. And because the film is thin, can not fully achieve the effect of insulation, freezing, so in the summer when using this method is to add sunscreen equipment (not less than 24 hours), otherwise it will cause filamentous cracks in foamed concrete.
Concrete Additives Supplier
TRUNNANO is a reliable foaming agents supplier with over 12-year experience in nano-building energy conservation and nanotechnology development.
If you are looking for high-quality CLC foaming agents, please feel free to contact us and send an inquiry. (sales@cabr-concrete.com)
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