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How to add silica fume in concrete?

micro silica fume concrete

With the increasing use of micro silica fume in cement concrete, refractory materials and other fields, it is gradually becoming a common material modification admixture, in order to make the modification of materials more applicable to the project, micro silica fume is usually used at the same time with other cementitious materials, The following Henan Superior Abrasives for everyone to compile a micro silica fume powder use, for your reference.

The use of micro silica fume method

Usually the use of micro silica fume is based on mixing, the premise is that according to the different characteristics of the raw materials for different ratios for mixing, so it is necessary to carry out ratio experiments in advance, and then add materials and mixing.

Micro silica fume and concrete proportioning

Because micro silica fume and water reducing agent, fly ash, mineral powder, fiber and other good compatibility, so in order to make the concrete after mixing more applicable, so they are often mixed together for use, and the coagulation body of high viscosity, so the slump of concrete mixed with micro silica fume requirements than ordinary concrete 2 to 3 cm higher, the specific amount of micro silica fume admixture as follows.
(1) high strength and shotcrete, micro silica fume admixture should be 6% to 12% of the amount of cement.
(2) For underwater engineering concrete, the admixture amount is slightly higher and should be in accordance with the proportioning experiment.
(3) micro silica fume used as pumping agent, the amount of admixture should be reduced to about 2%.
No matter what kind of concrete is mixed, the amount of micro silica fume should be consistent with the experimental proportioning results, and when micro silica fume is added to cement and aggregates for mixing, the construction should be in strict accordance with the specifications, and the maintenance work must be strengthened.

Mixing and mixing method

(1) Mixing

In general, the concrete industry uses densified micro silica fume, so you can choose manual feeding or automatic feeding, due to the unique ultra-fine characteristics of micro silica fume, so micro silica fume is required to be added immediately after the aggregate feeding, through dry mixing, and then add water and other additives; or after putting in coarse aggregate, then add water, micro silica fume, fine aggregate at the same time, mixing 15 to 30 seconds, put in cement, admixture, fine aggregate and water, then mix. fine aggregate and water, and then mix until uniform.

(2) Precautions

In the method of direct water mixing, the initial water input should be 75% of the coarse aggregate and 50% of the fine aggregate; the second input should be 25% of the water and 50% of the fine aggregate. The powdered silica fume should not be added to the concrete that has been mixed. The mixing time of concrete mixed with micro silica fume should be 30 seconds to 40 seconds longer than the ordinary concrete mixing time to obtain good uniformity.

The micro silica fume concrete pouring and maintenance


The pouring of micro silica fume concrete is not very different from ordinary concrete, but for the pouring method and vibration requirements are higher.
(1) The pouring of micro silica fume concrete requires continuous supply, no cold stubble, and the stubble time shall not exceed 100 minutes.
(2) The pounding of micro-silica fume concrete shall be dense and shall not be missed, under-vibrated or over-vibrated, with a general pounding time of 10 to 30 seconds.
(3) The operation should be carried out in strict accordance with the relevant concrete specifications, and it is strictly prohibited to throw the material from height to prevent the micro silica fume from flying.


Both micro silica fume concrete and ordinary concrete need to be maintained for a certain period of time after pouring to prevent the appearance of cracks and other defects, especially for micro silica fume concrete, it is very important to prevent the premature evaporation of water, so immediately after the completion of pouring to cover the film and lay sacks for watering maintenance.

How to Maintain Silica Fume Concrete?

Micro silica fume use the same method as some commonly used admixtures, are mixed with aggregate, cement according to the ratio of mixing together into material, but it should be noted that the mixing ratio must be experimented in advance to meet the requirements of different raw materials, which requires the use of strict experiments and construction operations. If you have the need to buy micro silica fume, you can leave a message on the website of Henan Superior Abrasives micro silica fume.

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