Granulated Blast furnace slag (GBS) is a light coloured 0/4mm glassy sand produced by the rapid quenching of molten blast furnace slag using large volumes of water.
GBS or Granulate as it is sometimes known is produced by rapidly cooling molten Blast furnace slag with water as the slag is tapped from the furnace. Large volumes of water are required to be sprayed at the molten slag (10 parts water to 1 part slag is optimum) and the resulting product is then pumped to and dewatered within the granulation plant, which as well as processing the granulated slag also recovers the water for cooling and reuse.
Having a relatively high moisture content the material is allowed to drain by stockpiling. This process must be carefully managed in order to maximise its hydraulic properties.
Size (mm)
% Passing
2mm
95%
1mm
60%
0.5mm
20%
0.125mm
1%
Substance
% Value
CaO
38
MgO
9
SiO2
34
Al2O3
14
Property
Value
Relative Density
2.95
Mohs hardness
8
*The main application for GBS is as a cement replacement and this is covered in more detail on Cementitious Slag Makers Association webpage CSMA - The Cementitious Slag Makers Association.