Detailed Technical Parameters Of Micro Silica Fume

Silica powder-also called silica fume-also called micro silica fume-or ultrafine silica powder

Silicon micropowder is an ultra-fine siliceous powder material formed by the rapid oxidation and condensation of SiO2 and Si gas produced during the smelting of ferrosilicon alloy and industrial silicon and oxygen in the air.

1. Physical and chemical properties of silica powder:

1. Silica powder: the appearance is gray or off-white powder, and the refractoriness is >1600℃. Bulk density: 200～250 kg/m3. The chemical composition of silica fume is shown in the following table:

Item SiO2 Al2O3 Fe2O3 MgO CaO NaO PH

Average 75～96% 1.0±0.2% 0.9±0.3% 0.7±0.1% 0.3±0.1% 1.3±0.2% neutral

2. The fineness of silica fume: more than 80% of the silica fume has a fineness of less than 1 micron, the average particle size is 0.1-0.3 microns, and the specific surface area is 20-28m/g. Its fineness and specific surface area are about 80-100 times that of cement and 50-70 times that of fly ash. The commonly used specifications of quartz powder are 400 mesh, 800 mesh, 1000 mesh, 1500 mesh and 2000 mesh.

3. Particle morphology and mineral phase structure: During the formation process of silica fume, due to the effect of surface tension in the process of phase change, amorphous spherical particles of amorphous phase are formed, and the surface is relatively smooth, and some have multiple circles. An agglomerate of spherical particles sticking together. It is a volcanic ash material with a large specific surface area and high activity. For materials mixed with silica fume, tiny spheres can play a lubricating effect.

2. Function: Silica powder can fill the pores between cement particles, and at the same time form a gel with the hydration product, and react with the alkaline material magnesium oxide to form a gel. In the cement-based concrete, mortar and refractory castables, mixing a proper amount of silica fume can play the following roles:

1. Significantly improve compressive, flexural, impermeable, anti-corrosion, impact and abrasion resistance.

2. It has the functions of retaining water, preventing segregation, bleeding, and greatly reducing the resistance of concrete pumping.

3. Significantly prolong the service life of concrete. Especially in harsh environments such as chloride salt pollution erosion, sulfate erosion, high humidity, etc., the durability of concrete can be doubled or even several times higher

4. Significantly reduce the floor ash of sprayed concrete and castable, and increase the thickness of single sprayed layer

5. It is a necessary component of high-strength concrete, and C150 concrete has been applied in engineering.

6. It has about 5 times the effect of cement. It can reduce costs and improve durability when used in ordinary concrete and low cement castables.

7. Effectively prevent the occurrence of concrete alkali aggregate reaction.

8. Improve the compactness of cast refractories. When coexisting with Al2O3, it is easier to form a mullite phase, which increases its high-temperature strength and thermal shock resistance.

3. Scope of application:

Commercial concrete, high-strength concrete, self-leveling concrete, unshaped refractory, dry-mixed (pre-mixed) mortar, high-strength non-shrinkage grouting, wear-resistant industrial floor, repair mortar, polymer mortar, thermal insulation mortar, impermeable concrete , Concrete compacting agent, concrete preservative, cement-based polymer waterproofing agent; reinforcement of rubber, plastic, unsaturated polyester, paint, coating and other polymer materials, modification of ceramic products, etc.

4. Application areas:

1. Used in mortar and concrete: high-rise buildings, seaports, reservoirs, dams, water conservancy, culvert gates, railways, highways, bridges, subways, tunnels, airport runways, concrete roads and coal mine tunnels, etc.

2. In the material industry:

(1) High-grade, high-performance, low-cement refractory castables and preforms have a service life three times that of ordinary castables. The refractoriness is increased by about 100℃, and the high-temperature strength and thermal shock resistance are significantly improved. Has been widely used in: coke oven, ironmaking, steelmaking, steel rolling, non-ferrous metals, glass, ceramics and power generation industries.

(2) Large iron trenches and ladle materials, air-permeable bricks, patching materials, etc.

(3) Self-flowing refractory casting material and dry and wet spraying construction application.

(4) Oxide bonded silicon carbide products (ceramic kiln furniture, flame screens, etc.).

(5) High-temperature calcium silicate light-weight thermal insulation material.

(6) The corundum mullite push plate is used for the electric porcelain kiln.

(7) High temperature wear-resistant materials and products.

(8) Corundum and ceramic products.

(9) Sialon combined products.

In addition to being widely used in castable refractories, it has also been widely used in fused and sintered refractories.

3. New wall materials and facing materials:

(1) Polymer mortar, thermal insulation mortar and interface agent for wall insulation.

(2) Cement-based polymer waterproof material.

(3) Lightweight aggregate thermal insulation and energy-saving concrete and products.

(4) Putty powder processing for interior and exterior wall construction.

4. Other uses:

(1) Silicate brick material.

(2) Production of water glass.

(3) Used as a reinforcing material for organic compounds. Because its composition is similar to white carbon black produced by gas phase method. It can be used as a filling and reinforcing material in polymer materials such as rubber, resin, paint, paint, unsaturated polyester.

(4) Used as an anti-caking agent in the fertilizer industry.

5. Usage and precautions:

1. Dosage: generally 5-10% of the cementing material. The doping method of silica fume is divided into internal doping and external doping.

(1) Internal mixing: Under the premise of the same amount of water added, 1 part of silica fume can replace 3-5 parts of cement (weight) and maintain the compressive strength of concrete to improve other properties of concrete

(2) Addition: The amount of cement remains unchanged, and the addition of silica fume can significantly improve the strength and other properties of concrete. When concrete is mixed with silica fume, there is a certain slump loss. This point needs to be paid attention to during the mix ratio test.

Silica fume must be used in conjunction with a water reducing agent. It is recommended to mix fly ash and ground slag to improve its workability.

When using silica powder to prepare concrete, the weight ratio to cementitious material is generally:

(1) High performance concrete: 5-10%;

(2) Hydraulic concrete: 5-10%

(3) Shotcrete: 5-10%;

(4) Pump aid: 2-3%;

(5) Wear-resistant industrial floor: 6-8%;

(6) Polymer mortar, thermal insulation mortar: 10-15%,

(7) Unshaped refractory castable: 6-8%. Before use, please select a reasonable and economical dosage based on actual needs through experiments.

2. Adding method:

Silica powder concrete and castable should be made by the laboratory for construction mix ratio. Construct in strict accordance with the mix ratio. In the mixing of silica fume concrete, silica fume should be added to the mixer immediately after the aggregate is added. There are two ways to join:

(1) Put in aggregate, then put in silicon powder and cement dry mix, then add water and other additives.

(2) Put in coarse aggregate + 75% water + silica fume + 50% fine aggregate, stir for 15-30 seconds, then put in cement + admixture + 50% fine aggregate + 25% water, and stir until uniform. The mixing time is 20-25% or 50-60 seconds longer than ordinary concrete. Never add silica fume to the mixed concrete.

3. Construction method:

There is no major difference between the construction method of silica fume concrete and ordinary concrete, but it is necessary to organize well and vibrate and compact during construction. The early strength of silica fume concrete will advance the final setting time, so care should be taken when plastering the surface; at the same time, adding silica fume will increase the viscosity of the concrete and greatly reduce bleeding, making it slightly difficult to plaster the surface.

4. Construction safety:

The construction safety of silica micro-powder concrete should be strictly in accordance with the relevant national construction codes of concrete engineering. However, because the silica powder is relatively light, it is strictly forbidden to throw materials at high altitude to prevent silica fume flying

5. Product packaging, storage and transportation:

1. This product is packed in a laminated plastic woven bag. The packaging specifications are: 30 kg/bag, 25 kg/bag, 20 kg/bag.

2. This product should be stored in a dry, rain-proof and shaded environment. The product agglomerates with water and loses its activity. Do not expose to the sun for a long time to avoid weathering of the packaging bag and spilling the product

3. This product is not classified as dangerous goods, and transportation can be handled in accordance with the "Non-Dangerous Goods Regulations".