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What are concrete admixtures? Is silica fume an admixture?

HSA Grade 95D Ssilica Fume

Concrete is one of the main civil engineering materials nowadays, with the characteristics of low price and simple production process, and also because of its high compressive strength, wide range of strength levels and good durability performance, so the actual use is also increasing. But ordinary concrete in a large extent can not meet some special performance requirements of the project, so generally will be added to the admixture to improve the various properties of concrete, that what is concrete admixture? What are the concrete admixtures?

Concrete admixture

Concrete admixture generally refers to the concrete preparation process, and silicate cement or ordinary silicate cement together to form a cementitious material, silicon, aluminum, calcium and other one or more oxides as the main components, in concrete can replace part of the cement, with the specified fineness and coagulation properties, can improve the workability of the concrete mix and concrete strength, with volcanic ash activity, or potential water hardness of the Separate materials, the amount of admixture is generally not less than 5% of the amount of cementitious materials, the main role is to improve the workability, stability, durability and corrosion resistance of concrete.

What are the concrete admixtures?

Fly ash

Fly ash as one of the admixtures of concrete, in the same water-cement ratio, the amount of fly ash does not exceed 20%, the concrete performance is not much, only the temperature rise of concrete slightly reduced, only when the amount of more than 25%, fly ash on the performance of concrete will have a significant improvement.

Finely ground slag

The finer the slag is ground, the higher its activity, mixed into the concrete, the greater the heat of hydration of early production, the less conducive to reducing the temperature rise of concrete. When the specific surface area of slag exceeds 400m2/kg, used in very low water-cement ratio (less than 0.30) of concrete, the early strength of concrete increases since the increase in the amount of shrinkage admixture.

Silica fume (Microsilica)

Concrete mixed with silica fume, with the increase in the amount of silica fume, the water demand increases, since the shrinkage also increases, so generally the amount of silica fume is controlled between 5% to 10% better, and need to use high efficiency water reducing agent to adjust the water demand.

Mineral fine admixture

Mineral fine powder into the concrete has a good cohesion, improve the workability of fresh concrete; into the mineral fine powder, due to the corresponding reduction in cement clinker, the total heat of hydration of cement will be reduced, which can reduce the temperature rise of concrete; can adjust the strength of concrete development, and can improve the chemical erosion resistance of concrete, enhance the durability of concrete.

Concrete admixture characteristics

  1. Concrete admixture generally has a certain potential activity, can play the volcanic ash effect, morphological effect, micro-aggregate effect and interface effect, can replace 10% to 50% of the conventional ordinary silicate cement.
  2. Concrete admixture can also play a filling effect in the concrete, play a role in regulating the strength level of concrete or mortar.
  3. The fineness of admixture is finer than the fineness of cement mix, and its specific surface area is generally 400 to 450㎡/kg and above, or even higher, such as silica fume.
  4. The current mature concrete admixture has national standard or line standard, from the concrete material system, the cement mix can not replace the concrete admixture.
  5. Concrete admixture is the sixth must component of contemporary high-performance concrete.


Silica fume as a kind of admixture, although its admixture is not high, but with other admixtures after the use of the composite effect can meet the requirements of high-performance concrete use, Henan Superior Abrasives specializing in the production of a variety of undensified silica fume, densified silica fume, White Zirconium Silica Fume, advanced production technology, to meet the needs of different projects, such as interested in buying can be leave a message on the website, or through the E-mail, WhatsApp for Detailed consultation.

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