What determines the activity of micro silica powder (silica fume)?

The activity of Ewende micro silica powder (silica fume) is mainly determined by the following factors:

I. Chemical Composition

1. Silicon dioxide content: The high content of silicon dioxide in micro silica powder is an important basis for its activity. Silicon dioxide can react with calcium hydroxide in the process of cement hydration to generate hydrated calcium silicate with cementitious properties, thus improving the strength and durability of the material. Generally speaking, the higher the silica content, the higher the activity of micro silica powder.

2. Impurity content: impurities in micro silica powder such as iron oxide, alumina, calcium oxide, etc. will have an impact on its activity. A moderate amount of impurities can promote the active reaction of micro silica powder to a certain extent, but too many impurities will reduce its activity. For example, iron oxide can participate in the hydration reaction of cement and improve the early strength, but too much iron oxide may cause the color of concrete to become darker and affect the appearance quality.

II. Fineness

The fineness of micro silica powder has a great influence on its activity. The finer the fineness, the larger the specific surface area, the larger the contact area between micro silica powder particles and cement and other cementitious materials, the higher the reaction activity. Fine particles of micro silica powder can better fill in the gaps between the cement particles, promote the hydration reaction of cement, and improve the strength and durability of the material.

III. Particle Morphology

The particle morphology of micro silica powder also affects its activity. Spherical particles of micro silica powder has good fluidity, easy to disperse, and can better play its filling and active role. While irregularly shaped particles may affect the fluidity and compactness of the material, reducing its activity.

IV. The Calcination Temperature And Time

In the production process of micro silica powder, the calcination temperature and time also have a certain impact on its activity. Appropriate calcination temperature and time can make changes in the crystal structure of micro silica powder and improve its activity. However, too high calcination temperature and too long calcination time may cause the activity of micro silica powder to be reduced or even lost.

V. Storage Conditions

The storage conditions of micro silica powder will also affect its activity. If it is not stored properly, such as moisture, pollution, etc., it may lead to a decrease in the activity of micro silica powder. Therefore, when storing micro silica powder, care should be taken to keep it dry, ventilated, and avoid contact with other harmful substances.