Civil Engineering Reference
In-Depth Information
4.8.1 Fresh Concrete Properties
The slump of a concrete mix with ceramic waste aggregates depends on the nature
of the aggregates. The majority of ceramic aggregates reported in the literature
have higher porosities than normal aggregates, and therefore the incorporation of
these aggregates in the concrete mix decreases slump due to their high porosity,
rough surface texture and angular nature. Topcu and Canbaz (
2007
) observed
workability problems due to the use of tile waste as partial and full replacement of
coarse aggregate because of rough surface texture of the tile aggregates. Lopez
et al. (
2007
) and Guerra et al. (
2009
) observed a similar workability of concrete
with ceramic aggregates and natural concretes, when the latter was replaced by
various amounts of fine and coarse ceramic aggregates. On the other hand, ceramic
aggregates have some properties like lower water absorption than NA and smooth
surface texture that can increase the slump of the resulting concrete mix
(Senthamarai and Devadas
2005
). Debeib and Kenai (
2008
) observed some seg-
regation of concrete mix when brick waste was used as fine and coarse aggregates.
The variations of concrete's slump due to the incorporation of ceramic aggregates
given in various references are presented in Table
4.22
.
The density of concrete with waste ceramic aggregates is generally lower than
(or similar to) that of conventional concrete. Binici (
2007
) reported similar density
and air contents for conventional concrete and concrete mixes prepared by
replacing 40, 50 and 60 % by weight of sand by ceramic aggregate. Torkittikul and
Chaipanich (
2010
) observed a decreasing trend in the density of fresh concrete and
cement mortar mixes due to use of ceramic aggregates as replacement of sand
(Fig.
4.62
).
Brito et al. (
2005
) reported that the density of concrete decreased as the
replacement ratio of coarse limestone aggregates by similar size ceramic aggre-
gates increased, due to the lower density of ceramic aggregates compared to the
limestone aggregates. The bulk density of fresh concrete mixes with ceramic waste
with specific gravity of 2.45 as coarse aggregates with different w/c ratios in the
Senthamarai et al. (
2011
) study was in the 2215-2281 kg/m
3
range in comparison
to the equivalent range of 2383-2480 kg/m
3
for conventional concrete with granite
coarse aggregates with specific gravity of 2.68. Cachim (
2009
) observed about a 5
and 6 % decrease in fresh density at w/c ratios of 0.45 and 0.5, respectively, when
coarse NA were replaced by brick waste aggregates. Debeib and Kenai (
2008
)
observed a reduction of up to 17 % in the fresh density of concrete with brick
waste aggregates by comparison with NA concrete. The air content in concrete
also increased as the content of ceramic waste aggregates rose.
