Civil Engineering Reference
In-Depth Information
flexural strength performance. These authors also mentioned that a volume
replacement up to 20% did not generate a relevant tensile strength loss. an
increase in the replacement volume from 20% to 50% led to a 36% tensile
strength loss for polycarbonate mixtures while the same replacement volume
with PeT waste was responsible for a tensile strength loss of 11%.
Toughness
Silva et al. (2005) mentioned that recycled monofilament PET fibres increased
the toughness indexes of cementitious composites. also hannawi et al.
(2010) mentioned that PeT and polycarbonate wastes composites have a
high energy-absorbing behaviour even with a high waste content. Kim et al.
(2010) used embossed-type PET fibre, reporting that fibre concrete allows
a mid-span deflection that is four times higher when compared with free
fibre concrete. Investigations that clarify which treatment has the lowest
environmental impact but maximizes the toughness characteristics of PeT
concrete are needed.
Modulus of elasticity
Marzouk et al. (2007) reported that the modulus of elasticity of PeT-based
composites decreased slightly with increasing waste content up to 20% (just
5%). Beyond this level the modulus of elasticity presented a severe decrease
with waste content. a 40% replacement volume led to a decrease in the
modulus of elasticity of 21.4%. results also showed that mixtures with small
PET particles have lower modulus of elasticity. Kim et al. (2010) confirmed
the reduction in the elasticity modulus with increasing embossed PeT waste
fibres. However, since these authors used replacement volumes up just to
1.0%, they report irrelevant changes. The same happens with crimped PP
fibre-based mixtures. For steel-reinforced concrete beams these authors found
that using 0.5% embossed PET fibres led to maximum ductility. That makes
it 10 times higher than that of concrete beams without fibres.
Thermal insulation
Marzouk (2005) mentioned that a 50% volume replacement of fine aggregates
by PeT wastes led to a reduction of the thermal conductivity by 46% from 1.28
(W/m K) to 0.69 (W/m K). Yesilata et al. (2009) obtained a 10% reduction in
the thermal insulation of concrete specimens with square PeT particles with a
volume of 0.9% related to the volume of the concrete specimens. The results
also showed that when strip or irregular PeT particles were used the thermal
insulation of the specimens increased from 10% to 17%. The results showed
that square-type PeT particles have low adhesion to cement, resulting in a
