Micro-silica component indices Popularization and application of micro-silica, marking China's construction industry and ceramic production into high-tech refractory period, 80 years, due to the application of micro-silica powder has also led to other applications, with the development of the market changes, The construction industry, ceramics and refractories demand increasing, micro silica fume of its special physical and chemical properties will be subject to City Market is more pro-gaze, very broad application prospects. In recent years, micro-silica fume in the construction and building materials industry applications, to achieve Very good results, its use more and more broad. After the infiltration of silica fume cement concrete can well fill in the gaps among the cement, so that more micro-density slurry, in addition, With the dissociated Ca (OH) combine to form a stable calcium silicate hydrate 2CaO.SiO2. H 2O, the hydrates, condensate Gel strength is higher than Ca (OH) crystals, mainly reflected in: (1) to increase its strength. Of the concrete compressive strength, flexural strength greatly increased, infiltration of 5-10% silica fume, Compressive strength can increase 10-30%, flexural strength increased by 10% or more; (2) increasing the density. Impermeability performance 5-18 times more resistant capabilities increased by 4 times: (3) Frost Resistance: micro silica fume concrete in 300-500 times through the cycle of fast-freeze solution, the relative elastic modulus Reduced 10-20%, while the ordinary concrete by 25-50 cycles, the relative elastic modulus reduced to 30-73% ; (4) The early strength of: micro silica fume concrete to shorten the induction period, with early strength of character; (5) Anti-abrasion, cavitation control of: micro silica fume concrete abrasion-resistant than ordinary concrete ability to increase 0.5-2.5 Times, anti-cavitation ability to increase 3-16 times.
silica fume, also known as silica fume, microsilica or silica fume
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Slag
(B) molten blast furnace slag in the sudden cold, too late to form a glassy crystalline material. Was thin granular. Molten slag directly into the cooling pond known as water-quenching slag, commonly known as the water residue. After grinded slag, the activity of cement mixed material. SiO2 slag containing more acidic slag, containing Al2O3 and CaO and more for the basic slag. The activity of alkaline than acidic slag slag higher. Slag due to the water itself has a certain hard, not long-term storage. Slag
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Silica fume mix
For the silica fume concrete mix design is primarily based on design requirements to determine the silica fume incorporation method, the best dosage silica fume, superplasticizer dosage and the optimal adjustment of sand and gravel materials, while the other according to ordinary concrete design methods.
a) silica fume incorporation method: silica fume in concrete are generally two ways: First, doped within a second, Mixed, must be used in conjunction with the water reducer. Within the mixed method is often used instead of cement, silica fume, is divided into equal parts to replace, and replace the two kinds of contour, contour instead replaced by an equivalent dosage of silica fume cement, some substitute for 1 kg silica fume instead of 1 ~ 3 kg of cement, As a study of a general dosage of 5% ~ 30%, water-cement ratio has remained generally the same: the Law refers to the suits the doped silica fume as admixture in concrete as mixed, while cement consumption is not reduced dosage is generally 5% ~ 10%, generally derived from outside the mixed method of the mechanical properties of concrete is much higher, but increased the amount of cementitious materials in concrete.
b) silica fume is often controlled at the optimal dosage of 8% ~ 10%. It is based on silicon powder used in cement and the aggregate nature of the species, and to consider the extent of its performance improvement and construction of convenience or not, and the technical and economic indicators.
c) The best superplasticizer dosage: the use of silica fume in concrete, such as the non-doped water-reducing agent, want to maintain the same fluidity, it is bound to increase in water consumption, water-cement ratio increased, silica fume concrete strength do not go up, this is the past, silica fume in concrete are not promoting the use of reason. Joint use of silica fume and superplasticizer mixed with silica fume water-cement ratio remains unchanged, that is not to increase water consumption, but also can achieve with non-doped silica fume concrete with the same fluidity and strength of silica fume concrete performance is greatly improved generally more use of domestic naphthalene superplasticizer, such as the construction of 1, H, DH3, FDN, NF, N2B, with its dosage is generally 1% of the amount of plastic material within, and sometimes in order to reduce the water-cement ratio, mixing system for ultra-high strength concrete, water-reducing agent dosage up to 2% ~ 3%.
d) aggregate amount of adjustments: silica fume was generally do not have to adjust the amount of sand and gravel. Mixed with silicon powder and silicon powder to be deducted an equal volume of sand size.
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Silica fume in the material Industry areas
(1) high-end high-performance low-cement refractory casting materials and prefabricated parts, service life is three times the ordinary castable, refractoriness increase of about 100 ℃, high temperature strength and thermal shock resistance are all improved significantly. Has been widely used in: coke, iron, steel, rolled steel, nonferrous metals, glass, ceramics and power generation industries. (2) Large-scale iron and steel package Ditch materials, ventilation tiles, painting repair materials.
(3) self-flow casting refractory materials and construction of dry and wet spray application.
(4) oxide bonded silicon carbide products (ceramics kiln kiln, separated flame board, etc.).
(5) The high temperature calcium silicate insulation materials, light.
(6) electric kilns with corundum mullite push plate.
(7) high-temperature wear-resistant materials and products.
(8) corundum, and ceramics.
(9) Sialon-products. In addition to casting refractories currently in widespread use outside, in the fused and sintered refractories also received a large number of applications.
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Fumed silica in the physical and chemical properties
1, silica fume: the appearance of gray or off-white powder ﹑ Refractoriness> 1600 ℃. Bulk density: 200 ~ 250 kg / cubic meter. The chemical composition of silica fume in the table below:
Project SiO2 Al2O3 Fe2O3 MgO CaO NaO PH
Average of 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: silica fume in the fineness of less than 1μm to more than 80%, with an average diameter of 0.1 ~ 0.3μm, surface area: 20 ~ 28m2 / g. Of its fineness and specific surface area of about 80 to 100 times more cement, fly ash, 50 ~ 70-fold.
3, particle morphology and mineralogical structure: the formation process of silica fume, because the process of phase transition by the role of surface tension, forming a non-crystalline amorphous spherical particles, and the surface is smooth, while others are more round ball particles stick together in aggregates. It is a large specific surface area of active high-ash material. Mixed with silica fume materials, tiny spherical bodies can play a role in lubrication.
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Products, packaging, storage and transportation
1, this product uses laminated plastic woven bag packaging. Packing specification: 30 kg / bag, 25 kg / bag, 20 kg / bag, or tons of bags.
2, this product should be in dry, rain, sun storage environment. Agglomeration with water activity of product loss. Prohibited in the sun a long time exposure in order to avoid bags weathering products, sprinkle.
3, this product does not belong to dangerous goods, transport may be "non-dangerous goods rules" apply.
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Micro-silica thermal vibration enhancements
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Classification of micro silica fume
(A) of the SiO2 content to sub -
1, SiO2 ≥ 85%, a typical value of 88%, the main control loss on ignition (≤ 6%), for Concrete and low-grade refractory.
2, SiO2 ≥ 90%, a typical value of about 92%, according to customer requirements control related impurities, used in concrete and general refractories.
3, SiO2 ≥ 92%, a typical value of 94% or so, there are specific requirements (refer to AIKEN 940), the liquidity has requested for high-grade refractories.
4, SiO2 ≥ 97%, a typical value of 97% or more, and the impurities and the ph value of the strict requirements (refer to AIKEN 971), but focus on different customers is inconsistent, for high-grade refractories.
(B) the particle size or surface area to sub -
1, with a median diameter of 0.3um, the specific surface area value in the 15-25m2 / g, almost all the particle size ≤ 1um, the vast majority of the world fall into this category silica fume.
2, with a median diameter of about or below the 0.1um, specific surface area value ≥ 30m2 / g, usually appear in high-purity silicon powder silicon metal plant is relatively rare.
3, with a median diameter in the 0.5-2.0um, specific surface area value in the 5-15m2 / g, rare.
4, with a median diameter ≥ 2.0um, extremely rare, the use of poor performance.
(C) of sub-density
1, the status quo ,100-170kg / m3 easy bonding, poor delivery.
2, mild encryption ,250-400kg / m3, almost no particles conveying of significantly improved. However, affected by the temperature instability.
3, semi-encryption 400-500kg/m3, began to appear a large number of loose particles, difficult to bond, transportation is better.
4, high-density 500-700kg/m3, basically as hard particles dominated (and close particle size of different products in varying degrees), delivery of priority.
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Silica Fume (microsilica) engage
Silica Fume (microsilica) engage. Our major investment in production of ferrosilicon and silicon metal silicon powder and the dense line of production line a lot. Topken silicon in China, there are six different places smoke base. According to different quality, we supply silica fume different clients and different areas, such as refractory materials, concrete (HPC), water, mud, for XXXXX Now, our ability to add more than 3000 tons per month.
We have a good cooperation with China Building Materials Building Materials Research Institute and Shanghai Institute for Applied Technology and cooperative relations. When we micro-silica powder products are used in engineering, we can provide technical support to our customers. This is very important to China, because not all of the construction company or risk management company in the silica fume, in particular, are familiar with the new users. Now more and more important engineering projects regard Silica Fume important in China.
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