H y d r a t i o n P r o p e r t i e s o f I n o r g a n i c B i n d e r
667
HYDRATION PROPERTIES OF INORGANIC BINDER PRODUCED
FROM EAF REDUCING SLAG
Sun-Mi Choi
1
& Jin-Man Kim
2
& Ji-Ho Kim
3
1
Dept.of Architectural Engineering, Kongju National University, Republic of Korea
2
Dept.of Architectural Engineering, Kongju National University, Republic of Korea
3
Dept.of Architectural Engineering, Kongju National University, Republic of Korea
Abstract
The capacity of world steel production was about 1,413million ton in 2008. There are
several types of slag from steel production such as blast furnace slag, converted furnace
slag, and electric arc furnace slag. The electric arc furnace slag, abbreviated EAF slag,
is classified as EAF oxidizing slag and EAF reducing slag. The EAF reducing slag of this
research material, about 20% of the electric arc furnace slag, has high content of free
CaO and free MgO, which generate the expansion collapse by hydration reaction.
Although many researchers have been endeavoring to use the EAF reducing slag in
construction fields, there is not found the effective recycling method so far.
This study is to recycle the EAF slag as a useful resources in construction field. We try to
make the powder of EAF slag having the hydration vitality. To realize this, we atomized
the melting EAF reducing slag by high speed air and rapidly cooled in room temperature
to be small beads, likely as a cement clinker cooling process. The solidify EAF reducing
slag of small beads were pulverized in a ball mill. This thesis deals with the hydration
properties of this powder as an inorganic binder for construction materials.
As results of experiment, this powder contains the mayenite(C
12
A
7
or C
11
A
7
•CaF
2
) that
has quick setting characteristics and the β-C
2
S of main component of the Ordinary
Portland Cement. It shows to set quickly than a commercial regulated set cement, and is
found to be stable by the standard cement stability test of KS and JIS. In addition, it
shows so high hydration activity at the initial age of 1 hour, but that at the age of 28 day
shows 73% only of OPC.
Keywords:
EAF Reducing Slag, Atomizing, free-CaO, Rapidly Cooled process EAF slag,
Steel Slag
1. Introduction
Taking up 21.5% of domestic business sector, the steel industry, the second highest
energy-consuming industry after petrochemical industry, is a high energy spending
industry, and at the same time, discharges diverse slag.
Slag is the by-product that is inevitably generated in the course of manufacturing the
steel. It is the slag that floats over the melted iron in reaction with the materials added to
remove impurities from the irons melted in the furnace. Accordingly, the slag contains
various impurities and it is the main cause that restricts the utilization of slag.
Since various compositions are mixed in the slag, it is difficult to use it as the materials of
high added value and is used as raw materials of construction areas. In Korea,
7,063,000 ton, 63% of blast furnace slag(BFS) that takes 50% of steel slag in 2010, was
used as materials of Portland blast-furnace slag cement. 50% of convert and electric art
furnace slag generated in the steel furnace in the same period was used for roads and
26% as aggregate for embankment.
Generally, electric arc furnace slag generates about 0.05~0.07 ton per 1 ton of steel.
1)
Electric arc furnace slag is separated into oxidation and reducing slag according to
conditions in the furnace. While the compositions of slag generated from 2 process are
