Civil Engineering Reference
In-Depth Information
density polyethylene fibres and reported an improvement of the toughness
characteristics of concrete composites of up to seven times. Kou et al. (2009)
studied the influence of crush PVC wastes (Fig. 13.14) on the properties of
concrete composites, reporting a relevant compressive strength decrease with
the increase in waste content. Since PVc aggregates have a compressive
strength of 65 MPa the compressive strength reduction of the concrete
mixtures must be related to a low adhesion between PVc and the cement
paste. The PVc aggregates also contribute to the reduction of the modulus
of elasticity because of the low modulus of PVc. The results suggested that
concrete with increased PVc volume show a decrease in drying shrinkage.
For instance the use of just 15% PVc aggregates led to a 50% reduction in
the drying shrinkage. Studies about the durability of other polymeric wastes
are scarce but some authors have already reported that polyester and acrylic
fibres can suffer from chemical degradation when immersed in the alkaline
environment of a cement paste (Wang et al., 1987; Jelidi, 1991; houget,
1992).
13.5 Conclusion
Tyre rubber and PeT wastes represent a serious environmental issue that needs
to be addressed with urgency by the scientific community. Investigations
carried out so far reveal that tyre waste concrete is specially recommended
for concrete structures located in areas of severe earthquake risk and also for
applications subjected to severe dynamic actions such as railway sleepers.
This material can also be used for non-load-bearing purposes such as noise
reduction barriers. investigations of rubber waste concrete show that concrete
performance is very dependent on the waste aggregates. Further investigations
are needed to clarify, for instance, which characteristics maximize concrete
performance. as for PeT-based concrete the investigations show that this
13.14
PVC waste: left, before crushing; right, after crushing
(Alhozaimy and Shannag, 2009).
