Mubashir shaheryar Roll no#15 Section A

Assignment# 1 Mineral Admixtures; Silica Fume,

Fly ash ; Blast Furnace Slag, Rice husk ash; Volcanic ash

MINERAL ADMIXTURES• Mineral admixtures are fine grinded materials

like fly ash, silica fume, slag etc. The mineral admixtures are: Pozzolanic (Low-calcium )

• -Cementitious (Granulated iron blast-furnace slag)

• -Both pozzolanic and cementitious (Highcalcium)

• -Natural materials (Volcanic Ash)

FLY ASH• DEFINITION:

Fly ash is a by-product of the combustion of coal in thermal power plants. The dust system removes the fly ash,as a fine residue, from the combustion gases before they are discharged into the

atmosphere. EFFECT ON HEAT OF HYDRATION:

Replacement of cement by fly ash results in a reduction in the temperature rise in fresh Concrete. This is particular importance in mass concrete where cooling, following a large temperature rise, can lead to cracking

BLAST FURNACE SLAG

• PREPARATION: Blast furnace slag is

basically prepared in blast furnace by metallurgical process in which

iron ore ,coke, flux [limestone or dolomite] is added.In slag formation lime in the flux chemically reacted with aluminates and silicates present in ore to a non metallic product called blast furnace slag.

SILICON FUME

• DEFINITION: silicon

fume is by product of producing silicon metal.It is produced in electric arc furnace. USES:

It is used in concrete to increase its strength and durability.It is very reactive form of pozzolan.

RICE HUSK ASH• Rice husk ash is a pozzolanic

material.It gives strenght to cement and increases the durability of concrete.Rice husk ash has different form black ,white.Black rice husk ash is formed by incomplete combustion of carbon while white rice husk ash is formed by complete combustion of carbon.

VOLCANIC ASH

• DEFINITION: It is very

small solid particles ejected from volcano during the blast which have intermediate axes 2mm or less. USES: It is used in making portland cement by mixing with quicklime . Volcanic ash is used as admixture in concrete and cement