Z E M C H 2 0 1 2 I n t e r n a t i o n a l C o n f e r e n c e
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very different, it is mixed in the actual treatment process and statistics for generation and
recycling are not separated but integrated. Since KS F 4571 revised in 2010 specifies
that EAF oxidation slag can be used as fine aggregate and coarse aggregate, it is
expected that EAF oxidation slag can be smoothly recycled. On the contrary, EAF
reducing slag has not yet determined suitable recycling plan. It is because high contents
of f-CaO that causes disintegration and expansion. As of 2010, estimated amounts of
EAF reducing slag is over 700,000 ton and is used for reclamation and aggregate for
embankment after aging, mixed with EAF oxidation slag and aging.
If two slags are mixed, however, aging time gets longer and it acts as a factor to hinder
activation of recycling of electric arc furnace slag. In addition, reducing slag is very much
different from oxidation slag in terms of composition. Due to this, it is required to develop
the use of recycling by separating two slags.
This study is about the EAF reducing slag which is much less recycled than electric arc
furnace oxidation slag. Calcium oxide(CaO) and aluminum oxide(Al
2
O
3
) are the main
elements of reducing slag. It has the chemical composition from which hydration can be
expected if it goes through burnt reaction sufficiently. Since reducing slag is slowly
cooled right after discharge, however, its activity falls. In this regard, this study rapidly
cooled down the slag in the similar way as the cooling type of cement clinker, powered it
and examined its hydrate characteristics at room temperature in order to keep the
reactivity of reducing slag.
Also, it involves with thermal energy and reaction energy of high temperature when
rapidly cooled EAF reducing slag is in a molten state, revealing high reactivity and
hydration heat when it was undifferentiated and reacted with water.
Therefore, this study uses EAF reducing slag powder, an essential by-product from the
steel industry, as a binder for reactivity construction materials, and identifies availability
as a low-carbon inorganic binder which does not require calcinations process in high
temperature without using natural resources to use it as a basic material for utilizing a
high value-added alternative.
2. Experimental Plan
2.1 Experimental Plan
This experiment evaluated workability, hydrate characteristics and stability to check the
possibility of Rapidly Cooled EAF reducing slag powder(hereinafter "RC EAFRS powder)
as binder. RC EAFRS powder shows quick set when it reacts with water and compares
them in the same experiment as regulated set cement(RSC) and OPC as experiment
factors. Experiment was performed largely in 2 types such as paste experiment for
measuring material physical properties and mortar experiment for measuring strength
and length variation. Plans for this experiment is as shown in the Table 1.
Table 1: Experimental design
Division
Binder
Mix design
Test item
Paste
OPC
*
, RSC
**
, EAFRS
***
(* Ordinary Portland
Cement,
** Regulated Set Cement,
*** EAF Reducing Slag)
W/B : 50%
⦁
Setting time
⦁
Hydrate analysis(XRD, SEM)
⦁
Stability valuation(JIS, KS)
Mortar
W/B : 50%
B:S 1:2.45
⦁
Compressive strength
⦁
Length variation
