Brief analysis of the application of polycarboxylate superplasticizer in concrete

(Brief analysis of the application of polycarboxylate superplasticizer in concrete)

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.

 

1. Application status of concrete superplasticizer

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.

 

2. Application of polycarboxylate superplasticizer in modern concrete

l Categories of polycarboxylate 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.

 

l Key technologies for the application of polycarboxylate superplasticizers

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.

 

3. Problems existing in the practical application of polycarboxylate superplasticizers in concrete projects

l Effect of water consumption on the performance of polycarboxylic acid concrete mixture

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.

l Polycarboxylic acid concrete is prone to delamination and segregation

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.

l Unsatisfactory compatibility

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.

 

4. Conclusion

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).

(Brief analysis of the application of polycarboxylate superplasticizer in concrete)