Civil Engineering Reference
In-Depth Information
The sorptivity further decreased with increasing volumetric substitution up to
50 %. Thus, their results suggest better durability performance of cement mortar
with PET-aggregates than that of mortar with NA when in contact with aggressive
solutions. Hannawi et al. (
2010
) measured the water absorption and apparent
porosity values of the different mortar specimens with various amounts of PET and
PC waste aggregates. Their results revealed that replacing 3 % by volume of sand
by an equal volume of PET or PC do not exert influence either on water absorption
or on the apparent porosity of the composites in comparison with the control
mortar.
However,
apparent
porosity
and
water
absorption
increased
with
increasing plastic content.
Gas Permeability
Fraj et al. (
2010
) reported higher gas permeability (2.2 times) of concrete with dry
and prewetted PUR-foam aggregates than that of conventional concrete.
Prewetting the PUR-foam aggregates can further increase the value considerably.
Decreasing the w/c value and increasing superplasticizer content can reduce this
value for concrete with prewetted PUR-foam aggregates.
Hannawi et al. (
2010
) found an increase of helium gas permeability coefficient
with increasing plastic aggregates content in mortar, which indicated an increase
of the percolated porosity of mortar due to the incorporation of plastic aggregates,
because of weak bonding between the cement paste and plastic aggregates. They
also reported greater helium gas permeability coefficient of mortar with PET
aggregates than that of mortar with PC aggregates at the replacement level of 10,
20 and 50 % by volume of sand by plastic aggregates.
Chloride Migration
Kou et al. (
2009
) investigated the resistance to chloride-ion penetration of 28 and
91 days hardened concrete prepared by partially replacing natural fine aggregates
by PVC waste granules. The chloride-ion penetration resistance of concrete was
represented by the total charge passed in Coulomb during a test period of 6 h.
Their results (presented in Fig.
4.41
) indicated that this property improved with an
increase in PVC content as well as with curing time. They found reduction of
about 36 % in the total charge passed through the 28-day cured concrete, with
45 % replacement of NA by PVC granules in comparison to same-age concrete
with no PVC granules. According to them, the increase in the resistance to
chloride-ion penetration of concrete is attributed to the impervious PVC granules
blocking the passage of the chloride ions.
Fraj et al. (
2010
) evaluated the chloride diffusion coefficient of concrete with
rigid PUR foam as partial replacement of coarse NA. Their results are presented in
Table
4.13
. The authors observed lower chloride diffusion coefficient for concrete
with dry PUR-foam aggregates than that of concrete with NA only. However, the
