Page 85 - New Trends in Eco efficient and Recycled Concrete

60 New Trends in Eco-efficient and Recycled Concrete

aggregate (PA), which replaces NA, and as recycled plastic fibre (PF) in concrete.
Most of the existing studies conducted on the properties of PA concrete have shown
that their mechanical and durability-related properties are inferior to those of NA
concrete (Saikia and de Brito, 2012; Gu and Ozbakkaloglu, 2016; Ozbakkaloglu
et al., 2017). On the other hand, because of the high-energy consumption together
with the relatively high price and corrosion potential of steel fibres, a large number
of studies undertaken on the properties of PF concrete have reported that PF can be
considered a potential alternative reinforcement material to steel fibre to improve
the mechanical and durability-related properties of concrete (Yao et al., 2003; Hsie
et al., 2008; Kakooei et al., 2012; Pacheco-Torgal et al., 2012; Gu and
Ozbakkaloglu, 2016).
This chapter presents recent findings on how the properties of concretes contain-
ing PA and PF differ from those of conventional concrete. Material properties of
recycled plastics used in concrete are presented, followed by the preparation, physi-
cal properties, mechanical properties, durability properties and time-dependent
properties of PA and PF concrete. Fire resistance and thermal conductivity of PA
and PF concrete are discussed in the final section.

3.2 Material properties of recycled plastics used in
concrete

In studies conducted on the behaviour of recycled plastic concrete, high-density
polyethylene (HDPE), low-density polyethylene (LDPE), polyvinyl chloride
(PVC), polypropylene (PP), polyethylene terephthalate (PET), expanded polysty-
rene (EPS), un-EPS (UEPS), high-impact polystyrene (HIPS), ethylene-vinyl ace-
tate (EVA), polyurethane (PUR) and melamine aggregates were used in PA
concrete, whereas PP, nylon, PET, polyvinyl alcohol (PVA) and HDPE fibres
were used in PF concrete. Table 3.1 shows the properties of PA materials and
Table 3.2 shows the properties of PF materials used in the production of concrete
in the existing studies.

3.3 Preparation and physical properties of recycled
plastic concrete

Concrete containing PA is typically prepared by volume replacement of natural
coarse or fine aggregates with plastic coarse or fine aggregates. In most of the
existing studies in the literature, PAs were used at replacement levels of 30%
100%. PF concrete is typically prepared by the addition of PF into the concrete
based on the fibre volume fraction (i.e., the volume of fibres per unit volume of
concrete). In most studies, the volume fraction of PF in concrete was less than