Civil Engineering Reference
In-Depth Information
The surplus of this cheap material has led to attempts to accommodate
it in concrete. Maslehuddin et al. (1999), conducted detailed research of
steel slag as concrete aggregate. They investigated compressive and flex-
ural strength, water absorption, drying shrinkage and other properties of
concrete. Steel slag aggregate used in the experiments contained clay lumps
and friable particles in the range of 0.07% to 0.31%. Concrete with coarse
aggregate from steel slag has been assessed against concrete with limestone
aggregate. On the basis of the results of the study, its authors concluded
that steel slag aggregate can be beneficially utilised in Portland cement con-
crete but highlighted concerns with possible durability problems caused
by the lime expansion and aesthetic problems associated with the rust on
the surfaces.
Steel slag aggregate is a very abrasive material and will result in substan-
tial wearing of plant equipment (conveyer belts and bins) as well as agita-
tors. Due to the high density of steel slag (an apparent particle density of the
order of 3.3 t/m
3
), concrete density will increase making it suitable for appli-
cations requiring high density concrete. For instance, concrete with 1 t/m
3
of crushed river gravel (an apparent particle density of 2.65 t/m
3
) has a den-
sity of 2.44 t/m
3
and is delivered in maximum size loads of 6 m
3
. If crushed
river gravel is replaced with steel slag aggregate, the maximum load size will
be only 5.45 m
3
, which will increase concrete transportation cost.
3.6 CONCLUSION
As is the primary theme of this edition, it is concrete performance not com-
ponent performance that is important. Consideration of aggregate qual-
ity, other than its durability, should be the concern of the premix supplier
not the consultant or the regulator. Removing prescriptive components for
aggregate from concrete specifications is a most important requirement
for improving the sustainability of concrete.
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