Civil Engineering Reference
In-Depth Information
Etxeberria et al. (
2010
) observed lower compressive strength for concrete with
EAF-slag as the only coarse aggregates than that of a conventional concrete due to
a higher effective w/c value (0.69) than that of the conventional concrete (0.65).
However, in comparison with conventional concrete, the authors observed slightly
higher and almost equal compressive strength of concrete mixes prepared by
replacing, respectively, 25 and 50 % by volume of coarse nature aggregates by
slag. On the other hand, the compressive strength of concrete prepared at lower
w/c value increased with higher content of EAF-slag used to replace 0, 25, 50 and
100 % by volume of coarse NA (w/c equal to 0.57, 0.58, 0.59, and 0.60,
respectively).
Manso et al. (
2006
) observed low compressive strength of concrete with EAF-
slag as fine and coarse aggregates, due to its very poor workability behaviour. But
the compressive strength of concrete with EAF-slag was comparable to that of
conventional concrete at latter stages of curing (6 months and 1 year) when the
fine and coarse NA in concrete were replaced according to the following methods:
(1) complete replacement of coarse NA by similar size fractions of EAF-slag; (2)
complete replacement of coarse NA by similar size fractions of EAF-slag along
with the replacement of an equal amount of fine limestone aggregates by EAF-slag
fine aggregates. In the case of the second method, the grain size of limestone
aggregates was below 1 mm and therefore they act as a filler material.
Qasrawi et al. (
2009
) observed higher compressive strength for three different
types of concrete (with design cube strength of 25, 35 and 45 MPa) prepared by
replacing 15 and 30 % by weight of fine aggregates by steel slag than that for
conventional concrete. However, at the replacement ratios of 50 and 100 % by
weight, the compressive strength for all concrete types with slag aggregate were
lower than for conventional concrete. The increase in compressive strength of
concrete with EAF-slag up to a certain replacement level was due to the higher
angularity of steel slag aggregates compared to NA, which therefore increased the
binding between cement paste and aggregates. However, for higher slag incor-
poration levels, the percentage of the 0.15 mm aggregates fraction in concrete
increased due to the higher content of this fraction in slag (about 40 % of total
content). Thus, less cement was available to coat the slag particles and therefore
the paste-aggregate bonding decreased, which ultimately reduced the compressive
strength.
4.3.2.2 Splitting Tensile Strength
Several authors reported that the incorporation of steel slag as aggregates in
concrete increases the splitting tensile strength just like it does the compressive
strength as discussed in the previous section. However, results are also available
where improvements of compressive strength but deterioration of splitting tensile
strength was observed.
Al-Negheimish et al. (
1997
) observed higher 28-day splitting strength for
concrete with steel slag coarse aggregate than for conventional concrete at three
