In general, the fineness of Ewende silica fume is usually less than 1μm and the particle content is not less than 85%. The optimum dosage of different finenesses of silica fume in concrete is as follows:
– Coarse silica fume: For relatively coarse silica fume that still meets the above general fineness requirements, the optimum dosage of silica fume in concrete is usually about 5% – 8%. For example, in some of the early strength requirements are not particularly high, the construction environment is more common in the concrete project, the use of coarse silica fume and mixing in this range, both to improve the performance of the concrete, but also to ensure better constructability.
– Micro silica fume powder of medium degree of fineness: Micro silica fume powder of moderate fineness, the best mixing amount is generally 8% – 12%. In the preparation of high-strength concrete and high-performance concrete, the dosage of medium-fine micro silica fume powder in this range can give full play to its filling effect and volcanic ash effect, and effectively improve the strength, durability and other properties of the concrete, while not making the concrete too viscous and affecting the construction.
– Extremely fine micro silica powder: The fineness of the micro silica powder, the best mixing amount is usually controlled at 3% – 6%. Because its specific surface area is very large, although the filling effect and activity is better, but too much will lead to a substantial increase in the water demand of concrete, cohesion is too large, affecting the workability and strength of the concrete development, so in some special requirements of the precision concrete project, the mixing of very fine micro silica fume powder is appropriate to control the lower level.
