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what is silica fumes or micro silica? and whr is it used?
wat r its advantages?
 Question Submitted By :: Civil-Engineering
I also faced this Question!!     Answer Posted By  
# 1
Silica fume is 100 times more finer than cement. the
surface area for opc cement is 225 sqm/kg. silica fumes
gives more strength to the concrete as it fill the void
which exist between the cement partical Delhi metro rail
corporation is going to used for designing m80 or more
grade concre
Is This Answer Correct ?    54 Yes 3 No
# 2
Micro Silica (or) Silica Fume is a Finer particle than
Cement. It is used in High Strenght Concretes (Example .
M50,M60 & above).
The purpose is to fill the the small voids which cement
can't fill. The surface area of Micro Silica is appx 30000 -
45000 sqm/kg whereas for cement it is 350 - 600 sqm /kg.
Is This Answer Correct ?    41 Yes 2 No
# 3
Silica fumes and microsilica both are same.This product is
manfactures from reduction of high purity quartz(sio2) with
coal in an electric arc furnace in the manufacture of
silicon or ferrosilicon is 100 times finer than
cement.It can be used for high strength concrete as well as
durable concrete.
The use of Microsilica in conjuction with superplasticiser
has been achived high performance concrete. is more dense
and durable.As it is finer it can fill the pore spaces in
the concrete and could be achieved high resistance when
load will transmit.Also when the durablity will increase
chloride ion penetration from the water and soil can be
reduced and accordingly corrosion of reinforecment ceased.
Is This Answer Correct ?    25 Yes 5 No
Suresh Sathyavrithan
# 4
Micro Silica (or) Silica Fume is a Finer particle than
It is produced by some chemical processing of the Rice husk
It is used in High Strenght Concretes (Example .
M50,M60 & above).
The purpose is to fill the the small voids which cement
can't fill. The surface area of Micro Silica is appx 30000 -
45000 sqm/kg whereas for cement it is 350 - 600 sqm /kg.

Thanks for Marking this Answer
Is This Answer Correct ?    21 Yes 12 No
S B Lal Shrivastav
# 5
its same used with concrete as replacement for 6-10%
cement, adding this materials to concrete to increase the
strength as its finer than cement also to reduce the RCP
which is depending on % of silica which will replace by
Is This Answer Correct ?    7 Yes 2 No
# 6
Silica fume is also called Microsilica ,micro
silica ,silica dust ,which is widely used in concrete’s
field and refractory’s field, ceramic and rubber

Silica fume is a by-product from manufacturing silicon
metal or ferrosilicon alloys. The smoke that results from
furnace operation is collected and sold as silica fume,
rather than being landfilled. Silica fume is widely used in
concrete and refractory applicaton. One of the most
beneficial uses for silica fume is in concrete. Silica fume
consists primarily of amorphous (non-crystalline) silicon
dioxide(SiO2). The individual particles are extremely
small, approximately 1/100th the size of an average cement
particle. Because of its chemical & physical properties,
like high silica content & extreme fineness, silica fume is
a very effective pozzolanic material. Concrete containing
silica fume can have very high strength and can be very

Silica fume is added to Portland cement concrete to improve
its properties, in particular its compressive strength,
bond strength, and abrasion resistance. These improvements
stem from both the mechanical improvements resulting from
addition of a very fine powder to the cement paste mix as
well as from the pozzolanic reactions between the silica
fume and free calcium hydroxide in the paste. Addition of
silica fume also reduces the permeability of concrete to
chloride ions, which protects the reinforcing steel of
concrete from corrosion, especially in chloride-rich
environments such as coastal regions and those of humid
continental roadways and runways (because of the use of
deicing salts) and saltwater bridges.
Is This Answer Correct ?    7 Yes 3 No
# 7
Silica fume (SF)* is a by-product of the manufacture of
silicon metal and ferro-silicon alloys (Figure 1). The
process involves the reduction of high purity quartz (SiO2)
in electric arc furnaces at temperatures in excess of 2000°
C. SF is a very fine powder consisting mainly of spherical
particles or microspheres of mean diameter about 0.15
microns, with a very high specific surface area (15,000–
25,000 m2/kg). Each microsphere is on average
100 times smaller than an average cement grain. At a
typical dosage of 10% by mass of cement, there will be
50,000–100,000 SF particles percement grain (Figure
2).Class A SF (in accordance with an amendment to BS EN13263
[1]), contains at least 85% by mass of non-crystalline
SiO2. Alkalis are present only in small amounts (<
1%).Class B fume, which has an SiO2 limit of 75%, is
beyondthe scope of this paper.

SF functions in a concrete as a highly efficient pozzolan,
that is, it reacts chemically with the calcium hydroxide
produced by the hydration of the Portland cement (PC) to
form calcium silicate hydrates (C-S-H) which bind the
concrete together. SF is highly reactive due to the high
proportion of non-crystalline SiO2 and the large surface
area.In bulk, SF is generally dark grey to black or off-
white in colour and can be supplied as a densified powder
or slurry depending on the application and the available
handling facilities. SF is available
globally.Specifications for factory-produced cements
containing SF (referred to as CEM II/A-D) are included in
BS EN197-1[3]. Specifications are also given for its use as
a Type II (ie pozzolanic or latently hydraulic) addition to
concrete in BS EN 206-1[4] and BS 8500[5].There is no
health hazard associated with the use of SF as non-
crystalline silica is non-hazardous.

The dense microstructure of concrete containing SF leads to
major improvements in mechanical performance and resistance
to chemicals (such as acids, fuel oil, chlorides and
sulfates). Characteristics of hardened SF concrete
include:Lower permeability and improved durability (due to
the fine particle size and reactivity of SF)Greater
resistance to abrasion and impact than conventional
concretes of similar strength grade Compressive strengths
in excess of 60 N/mm2 are easily achieved. Higher flexural
strength and modulus of elasticity than conventional
concretes of equal compressive strength SF can be used as
an ingredient in high performance concretes containing
micro-fibres to combat explosive spalling during exposure
to fire. A properly designed SF high performance concrete
containing micro-fibres with a low water/cement ratio will
outperform conventional
concretes in terms of resistance to spalling during fire
(ACI 216)[7]Environmental benefits (due to reduced cement
contents and improved service life).
SF is ideally suited to the most demanding
applications,such as concrete slipways, dam spillways and
hardstandings, where chloride, chemical or abrasion
resistance are required. SF concretes have performed well
under these circumstances, as they are chemically stable
and have very low permeability.

Is This Answer Correct ?    4 Yes 0 No
# 8
Wuhan Newreach Chemical Co.,Ltd is active in exploiting,
producing and selling silica fume(microsilica)since 2001.It
has become a leader in the export of silica fume. We
provide high quality product with low price.Our silica fume
export to more than 20 countries to world-wide clients.
Rely on many years good reputation and good service, there
are many customers at home and abroad have established long-
term and steady business relatiomship with us.
Our Silica Fume not only supply to China Domestic. and
exported to Many countries like: India, Turkey, Korea,
Malaysia, Viet Nam, Thailand, Taiwan, United Arab Emirates,
Saudi Arabia, Philippines, Pakistan, Singapore, United
States, Hong kong, Kuwait, Indonesia, Iran, Egypt,
Australia, United Kingdom, Colombia, Cyprus, Italy, Syria,
Germany, Israel, Jordan, South Africa, Spain, Ukraine,
Canada, Kazakhstan, Japan, Ireland, Greece, Mexico,
Lebanon, New Zealand, Bulgaria, Brazil, Great Britain and
other countries.

(1) Quality
We supply stable and reliable silica fume to our customers.

(2) Price
Our silica fume price is low and reasonable.

(3) Convenient
We have warehouse in Shanghai, Tianjin, Guangzhou and
Wuhan. Delivery is fast and easy.

(4) Service
Our sales group are positive attitude to server you. We
have service feedback to ensure the service is good.
Is This Answer Correct ?    0 Yes 0 No
Ching Tseng-huang
# 9
silica fumes are used to manufactured fly ash cement.are
nothing but the lumps of silica.
Is This Answer Correct ?    12 Yes 46 No

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