BLAST FURNACE SLAG CEMENT - MANUFACTURE, PROPERTIES, ADVANTAGES, DISADVANTAGES AND USES

Blast Furnace Cement

Blast Furnace Cement is the mixture of Ordinary Portland Cement and fine granulated blast furnace slag.This slag is obtained in steel plant as the by product of steel making is produced during the seperation of the molten steel from impurities in steel making furnaces.

About 70% of slag is used in the manufacturing of blast furnace cement.Although blast furnace slag cement has low heat of hydration and it gives better resistance to chloride,sulphate and alkalies attacks.

Manufacture of Blast Furnace Cement

Ground granulated blast furnace slag cement (GGBFC) is obtained as a by products in the extraction of iron from its ore.The process of extraction of iron is called blast furnace.The slag that is obtained by quenching molten iron slag from a blast furnace in water or steam,to produce a glassy,granular product that is then dried and ground into a fine powder.

Constituents of the Ground Granulated Blast Furnace Slag Cement

CONSTITUENTS	PERCENTAGE BY MASS
CaO	38-50%
SiO2	27-39%
Al2O3	8-12%
MgO	Less than 10%

Properties of Blast Furnace Slag Cement

Density (g/cm3)   - 3.04

Specific Surface Area (cm2/g) -4050

SETTING TIME:

Initial Setting -  60 min

Final  Setting - 600 min

COMPRESSIVE STRENGTH (N/mm2)

  3 Days    - 23.5

  7 Days   - 36.1

28 Days  - 62.4

CHEMICAL COMPOSITION (%)

Magnesium oxide - 2.88

Sulphur tri oxide  - 2.19

Ignition loss          - 1.47

Uses Of Blast Furnace Slag Cement

1.It is used in ready mix concrete plants.

2.It is used in sub-structure,marine structure and pre-cast piles because it prevents sulphate and chloride attacks.

3.It is used in foundation because it requires low heat of hydration.

Advantages Of Blast Furnace Slag Cement

1.It provides good resistance to chemical attacks.

2.It provides good resistance to alkali-silica reaction.

3.Greater durability and reduced permeability due to fineness.

4.Initial setting time is more due to slow hydration process.

5.High workability (Due to its capicity to fill pores efficiently).

6..More economical compared to OPC.

7.Eco-friendly.

Disadvantages of Blast Furnace Cement

1.Initial Strength is low,so it cannot be used in RCC works.

2.It cannot be used in repair works because its initial setting time is high.