2. Ground Granulated
Blast-Furnace Slag “Cement” (GGBFS)
Ground Granulated
blast-furnace slag is the
correct technical term
for slag that is finely
ground and is used as a
separately batched
cementitious materials.
Slag is ground to the
fineness of Portland
cement or finer.
3. Ground Granulated Blast-Furnace
Slag “Cement”
Finely Ground granulated
blast-furnace slag
consisting of primarily
calcium and aluminum
silicates, used as a partial
replacement for Portland
cement in concrete
4. ASTM 989
Slag Cement
GGBFS – glassy granular material formed
when molten blast-furnace slag is rapidly
chilled as by immersion in water with or
without compositional adjustments made
while the blast-furnace is molten
5. Grades of Slag - ASTM C 989
Strength of 1:1 Slag: Cement Mortar
Slag Activity Index =
Strength of Control Cement Mortar
Grade 7-day Index 28-day Index
80 - 75
100 75 95
120 95 115
Requirements for average of 5 consecutive
6. Specifications and Grade of Ground Granulated
Iron Blast-Furnace Slags
ASTM C 989 (AASHTO M 302)
Grade 80
Slag with a low activity
index
Grade 100
Slag with a moderate
activity index
Grade 120
Slag with a high activity
index
7. Slag - Manufacture
Iron Blast Furnace
Iron ore is layered with a mixture of limestone
and coal or coke. The coal is the fuel. The
limestone is a flux that reduces fusion
temperatures.
The molten materials settle out at the bottom
and slag floats on the top of the pig iron. It is
tapped away
8. Slag - Manufacture
Iron Blast Furnace
Iron Ore Limestone/Coal
Fusion at
1400 to 1600 C
Slag
Pig Iron
9. Slag – Manufacture
Hot Runner
Molten blast furnace slag is tapped from the
blast furnace, moved through a hot runner on
the blast-furnace work floor. Dropped in a
“blow” box to a jet-process granulator.
GGBF is glassy - with the right chemistry and
morphology to form hydraulic cement when
finely ground.
12. Slag Products - Manufacture
Molten Slag is cooled
Air-cooled Aggregate
Palletized Granules & Pellets
Jet Process Granulator Granules
Granules are ground in a ball mill
Fineness similar to cement
14. SEM Micrograph of Slag Particles
Scanning electron microscope micrograph of
slag particles.
Scanning electron microscope micrograph of slag particles.
15. Slag - Characteristics
Cooled Rapidly - Glass
Fineness - 450 to 650 m2/kg
Specific gravity - 2.90
White to Buff color
Hydration - activated by alkalis
Forms cementitious silicates - C-S-H
16. Slag - Reactivity
Glass content
Fineness
Alkalis of reacting system
Concrete curing temperature
18. Slag - Typical Dosage
Application Dosage
( % by wt)
Exterior flatwork 35%
General use 35 to 50%
Mass Concrete 60 to 80%
Sulfate Resistance
Type II equivalent 35%
Type V equivalent 50%
Marine/chemical/heat >50% < 80%
19. Slag – Typical Dosage
Application Dosage (% by wt)
Exterior Flatwork 35%
General Use 35 to 50%
Mass Concrete 60 to 80%
Sulfate Resistance
Type II Equivalent 35%
Type V Equivalent 50%
Marine/chemical/heat >50%, <80%
20. Slag - Mixture Proportioning
Typical - 35 to 50% wt. cementitious
w/c ratio w/(cement + slag) ratio
Water demand - 1 to 5% lower
Admixture dosage
Similar for air entraining admixtures
May be lower for others
SG 2.90 - more abs. vol. than cement
33. Slag Cement and the
Environment
Recovered/ recycled material
Replaces Portland cement
Reduction of CO2
Reduction of Heat
Reduced Material extraction
Energy Saving
Lighter Color
34. LEED Credits
Leadership in Energy and Environmental Design
(LEED) is a system developed by the
United States Green Building Council to rate a
building's environmental performance.
This system has become the principal method by
which buildings can achieve green
building certification. The system is based on credits
earned in five major categories.
Slag cement can positively impact several credit
categories
35. LEED Categories
Site credit for reduction of heat islands: Use of high-albedo
materials like concrete
produced with slag cement.
Materials credit for building reuse: Slag cement makes
concrete structures more
durable.
Materials credit for recycled content: Slag cement is a
recycled material used in
concrete.
Materials credit for use of local/regional materials: Slag
cement can be considered
a local material in many areas.
For more information on the LEED system, visit www.usgbc.org
36. LEED Categories
Site credit for reduction of heat islands: Use of high-albedo
materials like concrete produced with slag cement.
Materials credit for building reuse: Slag cement makes
concrete structures more durable.
Materials credit for recycled content: Slag cement is a
recycled material used in concrete.
Materials credit for use of local/regional materials: Slag
cement can be considered a local material in many areas.
For more information on the LEED system, visit
www.usgbc.org.