Pozzolan is a siliceous or siliceous and aluminous material that in itself possesses little or no cementitious value but will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form compounds having cementitious properties. It is therefore classified as a cementitious material. There are both natural and artificial pozzolans. The quantification of the capacity of a pozzolan to react with calcium hydroxide and water is given by measuring its pozzolanic activity.
Microsilica (silica fume) is a by-product of silicon metal or ferrosilicon industries, is an amorphous silicon dioxide SiO2. This product reacts chemically with the calcium hydroxide in the cement paste which yields a calcium silicate hydrate gel that significantly enhances strength and durability. The super fine microsilica fills the voids between cement particles creating a very dense, less permeable concrete.
Physical characteristics:
Color: gray or gray white powder
Bulk density: 320-700 kg/m3
Chemical composition:
Items SiO2 Al2O3 Fe2O3 MgO CaO Na2O Moisture
Content
75-98%
1.0-0.2%
0.9-0.3%
0.7-0.1%
0.3-0.1%
1.3-0.2%
Fineness:
the fineness of the silica fume is less than 1 1/4m, and the average particle size is 0.1 0.3 1/4m, and the specific surface area is 20 - 28 m2/g. The fineness and specific surface area are about 80-100 times of cement and 50-70 times of fly ash.
Maxtech Micro Silica supplies will be as per QCS 2014 (ASTM C1240):
SiO2: >/= 92%
LOI: <6
Moisture Content: <1%
Activity Index at 7 days: > 105%
Application & Benefits of Microsilica (Silica fume):
In concrete:
The micro silica fume powder can be well filled in the cement particle space and make the slurry denser, mainly in the following:
Increase strength
Increase the density
Frost resistance
Early strength
Anti abrasion and anti-cavitation resistance
In Refractories:
Microsilica powder is widely used in the refractory industry. It has an important effect on the improvement of the amorphous refractory.
The production of amorphous and shaped refractory products as additives makes the strength and high temperature performance greatly improved.
Other Application:
Elastomers/Polymers
