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.
Polycarboxylic superplasticizer representative items can be split into two categories according to their primary chain structures: one is based upon acrylic or methacrylic acid as the main chain and is implanted with polyethers of various side chain lengths. The other type is polyethers with maleic anhydride as the main chain implanted with different side chain lengths. Based on this, series of high-performance water decreasing representative items with different characteristics have actually been obtained.
Before the introduction of polycarboxylic acid admixtures, there were lignosulfonate admixtures, naphthalene sulfonate formaldehyde condensates, melamine formaldehyde condensates, acetone sulfonate formaldehyde condensates, sulfamate formaldehyde condensates, etc. In the very early 1980s, Japan took the lead in efficiently establishing polycarboxylic acid-based water decreasing agents. The brand-new generation of polycarboxylic acid-based high-efficiency superplasticizer representatives has gotten over a few of the drawbacks of typical superplasticizer agents. It has reduced dosage, excellent downturn retention efficiency, low concrete shrinking, solid adjustability in molecular structure, excellent potential for high performance, and high manufacturing performance. Outstanding benefits include not using formaldehyde while doing so.
For the synthesis of polycarboxylate superplasticizer agents, the design of the molecular framework is crucial, consisting of the primary chain groups in the molecule, side chain density, and side chain length. The synthesis techniques mainly consist of an in-situ polymerization grafting approach, polymerization first and after that functionalization approach, and straight copolymerization of monomers.
Using polyether as the medium for the polymerization reaction of unsaturated monomers allows the major chain polymerization and the intro of side chains to proceed simultaneously. The process is easy, and the molecular weight of the synthesized water decreasing representative can be regulated to a certain degree. However, this approach includes the ester. The chemical reaction is a relatively easy to fix reaction and is carried out in a liquid service, leading to a reasonably low grafting price and has been slowly gotten rid of.
This technique generally manufactures the primary chain of the superplasticizer representative first, and then uses various other approaches to present the side chains for functionalization. This technique is hard to run. The molecular framework of the superplasticizer agent is stringent and the monomers have inadequate compatibility, making Using this method has actually been significantly limited.
This method is to very first prepare energetic macromonomers and then copolymerize little monomers and macromonomers in an aqueous remedy under the initiation of an initiator. As the synthesis procedure of macromonomers comes to be progressively mature and there are a growing number of kinds, this synthesis technique has become one of the most typically made use of method for the synthesis of polyesteric acid superplasticizer representative at this phase.
In several concrete tasks, standard high-efficiency concrete such as naphthalene series, is progressively incapable of meeting project needs due to limitations in technological performance. The brand-new generation of superplasticizer agent that has attracted much focus at home and abroad, polycarboxylic acid-based high-performance superplasticizer agent, has actually genuinely created an effective molecular structure based upon the system of distributed cement. It has a super-dispersed type and can prevent concrete depression loss. It does not cause obvious retardation, puts in a high plasticizing effect at low doses, has excellent fluidness retention, has a large level of flexibility in concrete adapting to a vast array of molecular frameworks, has numerous artificial innovations, and has wonderful space for high performance. It is good for concrete reinforcement. The result is exceptional. It can minimize the contraction of concrete and has incredibly reduced dangerous substance web content and various other technical performance attributes, providing the concrete exceptional building and construction workability, great toughness advancement, exceptional toughness, and the polycarboxylic acid-based high-performance superplasticizer representative has good Comprehensive technological efficiency benefits and environmental management functions meet the needs of modern-day concrete tasks. Consequently, polycarboxylic acid-based high-performance superplasticizer admixtures are gradually ending up being the first choice of admixtures for creating high-performance concrete. According to reports, the usage of polycarboxylic acid admixtures in Japan represents more than 80% of all high-performance admixture items, and The United States, Canada, and Europe likewise represent more than 50%. In my country, polycarboxylate superplasticizer representatives have been efficiently used in massive water conservancy, bridge, nuclear power, and train jobs such as the Three Gorges Dam, Sutong Bridge, Tianwan Nuclear Power Terminal, and Beijing-Shanghai High-speed Train, and have attained exceptional results.
At the same time, polycarboxylate superplasticizer representatives likewise have some problems:
1. Insufficient slump retention in high-temperature atmospheres.
2. Strong temperature sensitivity. If the same polycarboxylate superplasticizer representative is constructed in various periods, the depression retention of concrete will certainly be really various.
3. There are few practical products, and it is tough to satisfy the needs of ultra-high and ultra-long distance concrete pumping, adverse temperature building and construction, prep work of ultra-early stamina concrete, and high toughness of concrete.
4. High thickness, high admixture, low In the prep work of water-cement concrete, the viscosity of the concrete is high, which is not for construction.
5. It is very sensitive to the mud web content of sand and gravel aggregates.
6. It has poor flexibility to industrial sand and is sensitive to the dose, which impacts building and construction.
TRUNNANO is a supplier of CLC concrete with over 12 years experience in nano-building energy conservation and nanotechnology development. It accepts 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. If you are looking for high-quality concrete additives, please feel free to contact us and send an inquiry. (sales@cabr-concrete.com).
With the fast development of contemporary building modern technology, specifically the commercialization of regular concrete, individuals have greater and greater demands for concrete stamina modern technology. However, simply making concrete reach the layout toughness can no longer meet the needs of the advancement of modern-day culture. Satisfy the conditions of environmental protection, longevity and some unique engineering demands.
In order to enhance the building efficiency, mechanical residential properties and toughness of concrete, products such as concrete admixtures and admixtures have actually gotten excellent interest. Admixtures continue to introduce and progress with the advancement of concrete. Currently, polycarboxylic acid admixtures are widely used in concrete. It is widely used in structures. The high water reduction rate and high adaptability of polycarboxylic acid can effectively improve the performance of concrete. In practical applications, it facilitates transportation and improves construction speed and quality. Therefore, the application of polycarboxylate superplasticizer representative not only greatly enhances economic advantages, yet likewise improves the top quality and sturdiness of modern-day structure structures in useful applications.
In modern concrete, commonly used superplasticizers mainly include polycarboxylic acid-based, naphthalene-based, fatty acid-based superplasticizers, etc. Different superplasticizers have their own advantages and disadvantages. The following analyzes the characteristics of superplasticizers commonly used in modern construction in concrete applications:
1) The superplasticizer property of naphthalene-based admixtures is generally 17%, and their compatibility with matrix materials is relatively narrow, while it is wider with sand and gravel materials. Their fluidity performance is average, their slump and expandability losses are relatively large, and their water retention is poor. Performance in terms of properties, adhesion, and climate adaptability is also relatively poor.
2) The superplasticizer home of fatty acid collection is generally 20%, and its common adaptability is similar to that of naphthalene series admixtures. Its fluidity is average, but its slump and expandability losses are small during use, and its adhesion and climate adaptability are good.
3) The superplasticizer property of polycarboxylate superplasticizer is generally 25%, and its compatibility with matrix materials is wide, but its compatibility with sand and gravel materials is narrow. During use, the slump and expandability losses are small and there is no loss. The fluidity is large, and the water retention, adhesion, and climate adaptability are all good, but the use of technology requirements is higher.
Comprehensive analysis shows that the polycarboxylate superplasticizer has good effects in all aspects, and all performance indicators are better than other types of superplasticizers.
In the process of China's rapid economic and technological development, polycarboxylate superplasticizers with efficient superplasticizer properties are often used in construction engineering concrete. Common ones include the following: polypropylene hydrochloric acid, methylpropionic acid, and maleic acid. Polymers, polymaleic acid, etc. Polypropylene hydrochloric acid superplasticizer has good compatibility with other types of cement during use and has been widely used in actual use. During use, the monomer acrylic acid is used as the matrix and combined with polyoxyethylene to obtain a product with a higher molecular weight. Methylpropionic acid and maleic acid polymers block superplasticizer polymers composed of methylpropionic acid and maleic anhydride in the form of monomers. They are compounded with other superplasticizers to ensure Improved fluidity and adsorption properties. Maleic acid is a water-insoluble, polymer-reactive fine-particle superplasticizer. The main chain of its molecular structure contains acid anhydride, intramolecular lipid and other groups. When ready-mixed concrete, the alkaline component will cause These molecular groups to be hydrolyzed. In this way, the water-insoluble polymer can be effectively changed into a soluble polymer. At the same time, under the action of the dispersant, it can slowly enter the solution. The hydrolysis phenomenon that occurs on the surface of the concrete proceeds gradually and slowly, effectively avoiding the slump loss of the concrete structure through slow dispersion.
In recent years, polycarboxylate superplasticizers have been widely used in many construction projects in China. Modern concrete has high requirements for external functional additives. Therefore, when adding the polycarboxylate superplasticizer to the concrete system, the following key technologies should be considered.
1) Polycarboxylic acid-based compatibility technology. Due to the special structure of polycarboxylic acid-based high-performance superplasticizers, they cannot be stored and used together with other superplasticizers, especially naphthalene-based superplasticizers. When different types of superplasticizers need to be used interchangeably, the pertinent containers must be thoroughly cleaned to prevent cross-contamination from influencing the high quality of the concrete. The adsorption performance of superplasticizers varies with different types of cement. Since polycarboxylate superplasticizers have a narrow compatibility range with cement, poor compatibility is inevitable. Therefore, it is necessary to increase its dosage or use different types of cement. To effectively solve this problem.
2) Polycarboxylate superplasticizer retarding technology. During the construction process, Because of the limited time it takes for the retarder to take effect, its utilization can effectively prolong the malleability of concrete. However, the incompatibility between the two must also be considered to avoid the reduction of concrete performance.
3) Air content control. The polycarboxylic acid superplasticizer has a good air-entraining effect and can be used together with defoaming agents, air-entraining agents, etc. By first eliminating and then introducing, the air web content of concrete can be regulated, and its workability and longevity can be enhanced.
4) Control of mud content in sand and gravel. The effectiveness of polycarboxylic acid-based high-performance superplasticizers can be influenced by the amount of mud present in sand and gravel. If the mud content in the sand and gravel exceeds 2%, the structure between the clay layers will absorb a large number of superplasticizer molecules, reducing the flow performance of the concrete. If the mud content during the construction process is relatively large, you should consider using a clay-resistant polycarboxylate superplasticizer.
The impact of water consumption is very clear. In actual concrete engineering applications, sometimes, if the water consumption is increased by 1 to 3kg/m3, the concrete will suffer from serious bleeding, which will cause defects such as pitting, sanding, and holes on the surface. Uniformity and construction quality cannot be guaranteed, resulting in reduced strength and durability of concrete structures.
In most cases, adding polycarboxylate superplasticizer to concrete will greatly reduce the viscosity of the slurry. At the same time, even if the dosage and water consumption of the polycarboxylate superplasticizer are optimal and no bleeding occurs, the concrete is prone to delamination and segregation, which is mainly manifested in the fact that the coarse aggregate will interact with the mortar. , the pure pulp separates and sinks in large quantities. This type of concrete mixture does not cause any vibration during concrete engineering pouring, and the phenomenon of delamination and segregation is also very obvious.
Traditional superplasticizers such as naphthalene series, aliphatic series, lignosulfonates, and sulfamates can be blended in any proportion to meet various concrete preparation requirements. These traditional superplasticizers are not only well soluble in water but can also achieve excellent superposition effects when used in combination. Polycarboxylate superplasticizer has great limitations. It can only be used in combination with traditional superplasticizer lignosulfonate, and its compatibility with other traditional superplasticizers is relatively poor. If used in combination with other types of traditional superplasticizers, not only is it difficult to achieve a superposition effect, but the fluidity of the concrete will also be very poor, water consumption will be greatly increased, slump loss will be serious, and the concrete will be dry and difficult to unload, the strength and durability of concrete will certainly be seriously impacted.
To sum up, the molecular structure of polycarboxylate superplasticizers is particularly flexible and unique, which can greatly improve the dispersion performance of concrete cement particles and achieve multi-functionality. Even if the concrete is highly efficient, With the characteristics of maintaining dispersion, reducing viscosity, and reducing shrinkage, the performance of all aspects of concrete has been greatly improved. It has very good development and application prospects.
Polycarboxylate high-performance superplasticizer has outstanding advantages and strong application potential in the use of construction concrete, but there are also many shortcomings. As long as the user is good at utilizing its advantages and improving the shortcomings in its application, the correct best results can be obtained by understanding and applying polycarboxylic acid high-performance admixtures.
5. Supplier
TRUNNANO is a supplier of polycarboxylate superplasticizer, which is concrete and relative products with over 12 years experience in nano-building energy conservation and nanotechnology development. It accepts 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. If you are looking for high-quality concrete additives, please feel free to contact us and send an inquiry. (sales@cabr-concrete.com).
What is concrete foaming agent?
Cement foaming agent is called foamed concrete foaming agent. It refers to an admixture that can reduce the surface tension of liquid and produce a large amount of uniform and stable foam. It is an admixture used to produce foamed concrete and can produce a very large amount of foam. substance.
How to use cement foaming agent
1. Because the cement foaming agent generally has a large concentration, directly adding it to the foaming machine will lead to low foam output and waste of the foaming agent. Directly added to the foaming machine generally results in high concentration and cannot produce high-quality foam. At the same time, it is easy to block the liquid inlet pump of the cement foaming machine. The relationship between the dilution ratio of the cement foaming agent and the foaming effect is very large. Therefore, the dilution factor is too high or too low, so there must be a very suitable dilution factor. When determining the reasonable dilution ratio of the cement foaming agent, on the one hand, it is necessary to refer to the dilution ratio suggested by the manufacturer, and on the other hand, it is necessary to do the test directly on the foaming machine to determine the appropriate dilution ratio of the foaming agent.
2. After determining the combined multiple, it needs to be diluted with water to form a foaming liquid, and then the foaming liquid is made into a foam product. Pour the water and foaming agent into a water tank and let it dissolve fully. After observing blisters, pour the prepared cement into the tank, and then use a stirring tool to fully stir it, and then send it through a high-pressure conveying pipe or manually. It is processed into the finished product in the wallboard machine.
Precautions for the use of cement foaming agent
1. Note that when the dilution ratio with water is too low, and the concentration of the foaming agent diluent is too high, the overall output of foam will decrease, and the amount of foaming agent used will increase. When the dilution ratio is less than 30 times, the production of foam decreases, and slumps appear in the slurry. When we dilute to 50 times, the overall foam production increases, and there is no obvious slump in the slurry. increased by 30%.
2. When the dilution ratio is too high, more foam is formed and less liquid is formed, the foam conversion rate of the foaming agent diluent is low, the foam output decreases, and the stability of the foam decreases. Therefore, only when the dilution ratio is appropriate, can the foam with high foam yield and high stability be obtained.
3. Note that when purchasing the main material foaming agent, it does not mean that the dilution ratio is high, but the amount is small. It is necessary to distinguish what type of foaming agent is. It will be less than the amount of animal foaming agent diluted 40 times.
TRUNNANO is a cement foaming agent 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.
If you are looking for high quality foaming agent , please feel free to contact us and send an inquiry.
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The strength of structural solid concrete should be tested separately according to different strength levels. The test method should adopt the method of curing the specimens under the same conditions; when the strength of the specimens cured under the same conditions does not reach or the strength of the specimens cured under the same conditions is When the requirements are met, the rebound coring method can be used for inspection.
The equivalent curing age during concrete strength inspection can be taken as the age corresponding to when the daily average temperature reaches 600°C·d daily, and should not be less than 14 days. Age periods with daily average temperatures of 0°C and below are not included.
During winter construction, the temperature when calculating the equivalent curing age can be used as the actual curing temperature of structural components, or it can be based on the actual curing conditions of structural components and the strength of the cured specimen under the same conditions is equal to the 28-day age test under standard curing conditions. The principle of strength of parts shall be jointly determined by the supervision, construction and other parties.
The selection of structural solid steel protective layer thickness inspection components should be evenly distributed and should meet the following requirements:
1) For non-cantilever beam panels, 2% of the number of components should be extracted, and no less than five components should be inspected.
2) For cantilevered beams, 5% of the number of parts and no less than 10 parts should be selected for inspection; when the number of cantilevered beams is less than 10, all parts should be inspected.
3) For cantilever plates, 10% of the number of parts and no less than 20 parts should be selected for inspection; when the number of cantilever plates is less than 20, all parts should be inspected.
For selected beam components, the protective layer thickness of all longitudinal stress-bearing steel bars should be inspected; for selected panels, the protective layer thickness of no less than 6 longitudinal stress-bearing steel bars should be selected for inspection. For each steel bar, three representative points should be selected to measure at different locations and the average value should be taken.
The thickness of the steel protective layer can be inspected using the non-damage or partial damage method, or the non-damage and partial damage method can be used for calibration. When using non-destructive testing methods for testing, the testing instruments used should be used for measurement and testing, and the testing operations should comply with the provisions of corresponding regulations. The detection error of the steel protective layer thickness inspection should not be more significant than 1mm.
When inspecting the thickness of the protective layer of steel bars, the allowable deviation of the thickness of the protective layer of longitudinally stressed steel bars should comply with the provisions of the table below.
The thickness of the protective layer of the longitudinal stress-bearing steel bars of beams and plates should be inspected and accepted separately and should meet the following requirements:
1) When the pass rate of the protective layer thickness of all steel bars is 90% or above, it can be judged as qualified;
2) When the qualification rate of the thickness of all steel protective layers is less than 90% but not less than 80%, the same number of components can be selected for inspection; when the qualification rate calculated based on the sum of two samples is above 90%, it can still be determined as qualified;
The selection of structural entity position and size deviation inspection components should be evenly distributed and comply with the following regulations:
1) Beams and columns are selected according to 1% of the number of components and no less than 3;
2) Walls and boards should be selected from 1% of representative natural rooms and no less than three rooms;
3) The floor height should be randomly checked at 1% of the representative natural rooms and should not be less than three rooms.
For the selected components, the inspection items and inspection methods should comply with the following table. The allowable deviations and inspection methods should comply with the provisions of Table 8.3.2 and Table 9.3.10 of GB50204-2015, "Code for Construction Quality Acceptance of Concrete Structure Engineering." Accurate to 1mm.
The wall thickness, plate thickness, and layer height can be inspected using non-damaging or partial damage methods, or the non-damaging and partial damage methods can be used for calibration. When using non-destructive testing methods for testing instruments used should be subjected to metrological testing, and the testing operations should comply with the current relevant national standards.
Structural entity position and size deviation items shall be inspected and accepted separately and shall comply with the following regulations
1) When the pass rate of the inspection items is above 80%, it can be judged as qualified;
2) When the pass rate of the inspection items is less than 80% but not less than 70%, the same number of components can be selected for inspection; when the pass rate calculated based on the sum of two samplings is above 80%, it can still be judged as qualified.
TRUNNANO is a supplier of concrete materials with over 12 years experience in nano-building energy conservation and nanotechnology development. It accepts 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. If you are looking for high-quality concrete additives, please feel free to contact us and send an inquiry. (sales@cabr-concrete.com).
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