some problems in the application of polycarboxylate superplasticizerii
Compatibility of polycarboxylate superplasticizer with other admixtures.
Beijing Dongke United Technologies Co.,Ltd.
Concrete Additives are chemical substance that is added in the process of mixing concrete, accounting for less than 5% of the cement mass, and can significantly improve the performance of concrete. The characteristics of concrete admixtures are many varieties and small dosage, which have a great impact on the performance of concrete, and have the characteristics of less investment, quick effect, and significant technical and economic benefits. With the continuous advancement of science and technology, admixtures have been used more and more, and admixtures have become the fifth important component of concrete in addition to the four basic components.
Admixtures can improve the anti-carbonation performance of concrete to a certain extent. There is a certain linear relationship between the carbonation depth and porosity of concrete. Admixtures have a great influence on the frost resistance of concrete. It has good performance, but the single addition of early strength agent has no effect on the frost resistance of concrete.
The commonly used concrete admixtures are mainly naphthalene superplasticizers, polycarboxylate superplasticizers and aliphatic superplasticizers.
Naphthalene-based superplasticizer: Naphthalene-based superplasticizer is a chemically synthesized non-air-entraining superplasticizer. The chemical name is naphthalene sulfonate formaldehyde condensate, which has a strong dispersing effect on cement particles. For the preparation of large-flow concrete, cast-in-place concrete and prefabricated components with early strength and high strength requirements, it has a good use effect, can comprehensively improve and improve various properties of concrete, and is widely used in highways, bridges, dams, ports. Wharf, tunnel, electric power, water conservancy and civil engineering, steam curing and natural curing prefabricated components, etc.
When the water-cement ratio remains unchanged, the initial slump of concrete is increased by more than 10cm, and the water reduction rate can reach 15-25%.
It has significant early strength and enhancement effects on concrete, and its strength is increased by 20-60%.
Improve the workability of concrete and comprehensively improve the physical and mechanical properties of concrete.
Good adaptability to various cements and good compatibility with other types of concrete admixtures.
It is especially suitable for use in the following concrete projects: fluidized concrete, plasticized concrete, steam-cured concrete, impermeable concrete, waterproof concrete, natural curing prefabricated concrete, reinforced and prestressed reinforced concrete, high-strength ultra-high-strength concrete.
The aliphatic superplasticizer is added to the concrete together with the mixing water, or a post-addition method can be adopted, and the aliphatic superplasticizer is added to the concrete to prolong the stirring for 30s;
Due to the high water-reducing rate of the aliphatic superplasticizer, a layer of yellow slurry will be secreted on the surface before the initial setting of the concrete, which is a normal phenomenon. After finishing the concrete, the color will be eliminated, or after the concrete is strengthened, the color will be eliminated naturally, and the color will be eliminated faster by watering and curing, without affecting the internal and surface properties of the concrete.
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Compatibility of polycarboxylate superplasticizer with other admixtures.
Polycarboxylic acid high-efficiency water reducing agent is characterized by low dosage and high water reducing rate.
Polycarboxylic acid water reducing agent with high efficient water reducing performance is often used in construction concrete.
Polycarboxylate superplasticizer is a new generation of water-reducing agent based on modified polycarboxylic acid.
Polycarboxylate (PCE) superplasticizers are known as high range water-reducing admixtures in concretes, such as ready-mix concretes, self-compacting concretes (SCC), ultra-high strength concretes (UHPC) and at the same time give an extended slump retention.
The polycarboxylic acid-based high-performance water-reducing agent, has truly designed an effective molecular structure based on the mechanism of dispersed cement. It has a super-dispersed type and can prevent concrete slump loss.