Civil Engineering Reference
In-Depth Information
Table 2.9
Mineralogical compositions of various slags
Authors
Country
Type of slag
Minerals identified
Rojas and Rojas
(
2004
)
Spain
EAF-slag
Wustite/plustite, magnesioferrite/magnetite, hematite,
larnite, bredigite/merwinite, gehlenite,
birnessite/groutellite (manganese oxides)
Faraone et al.
(
2009
)
Italy
EAF-slag
Fine fraction: glaucochroite (CaMn)
2
SiO
4
,
iron manganese oxide (FeMnO)
Medium: calcite (CaCO
3
), glaucochroite (CaMn)
2
SiO
4
),
iron manganese oxide (FeMnO), magnetite (Fe
3
O
4
),
portlandite (Ca(OH)
2
)
Tossavainen et al.
(
2007
)
Sweden
LDF-slag
Mayenite, (Ca
12
Al
14
O
33
), free MgO. b-Ca
2
SiO
4
,
c-Ca
2
SiO
4,
Ca
2
Al
2
SiO
7
BOF-slag
Larnite, b-Ca
2
SiO
4
, solid solution of (Fe,Mg,Mn)O,
solid solution of (CaMg)O
EAF-slag, S1
Merwinite, Ca
3
Mg(SiO
4
)
2,
c-Ca
2
SiO
4
, solid solution
of spinel phase (Mg, Mn)(Cr, Al)
2
O
4
EAF-slag, S2
b-Ca
2
SiO
4,
wustite-type solid solution ((Fe, Mg, Mn)O),
Ca
2
(Al, Fe)
2
O
5,
Fe
2
O
3
Kirschsteinite (CaFe
2+
(SiO
4
)), Mg-wustite
Qian et al. (
2002
)
Singapore
Kirschsteinite
based EAF-
slag
Luxan et al. (
2000
)
Spain
EAF-slag, S1
and S2
Major: gehlenite [Ca
2
Al(Al,Si)
2
O
7
], larnite (Ca
2
SiO
4
)
Minor: bredigite [Ca
14
Mg
2
(SiO
4
)
8
], manganese oxides
(Mn
3
O
4
, MnO
2
), magnesioferrite (MgFe
2
O
4
),
magnetite (Fe
3
O
4
)
while the granulated slag is used for cement manufacturing. Its use as aggregate in
concrete is not very usual although it has no behavioural problems, and there has
been little research work done on the subject.
Because of their more porous structure, blast furnace slag aggregates have
lower thermal conductivities than conventional aggregates. Their insulating value
is of particular advantage in applications such as frost tapers (transition treatments
in pavement sub-grades between frost susceptible and non-frost susceptible soils)
or pavement base courses over frost-susceptible soils.
The granulated blast furnace slag is formed due to rapid quenching of molten
slag, which converts it into a glassy state. Granulated slag possesses cementitious
properties if it is ground finely. The size and physical properties of granulated blast
furnace slag varies, depending on the chemical composition and method of pro-
duction. Numerous studies are available on the properties of cement and concrete
containing ground blast furnace slag as a latent hydraulic material. Slag cement is
the hydraulic cement that results when molten slag from an iron blast furnace is
rapidly quenched with water, dried and ground to a fine powder. Blast furnace slag
sand was recognised as meeting JIS A 5012 standards in 1981, and has also been
stipulated in guidelines for the Japan Society of Civil Engineers. It is also stipu-
lated as JIS A 5308 (ready-mixed concrete).
Air-cooled blast furnace slag (air-cooled slag) is prepared by cooling the molten
blast furnace slag slowly by ambient air. A small amount of water is generally used
