Page 122 - New Trends in Eco efficient and Recycled Concrete

96 New Trends in Eco-efficient and Recycled Concrete

approximately 22% and 43% with the addition of 10% and 30% of SR sand,
respectively.
Aules (2011) partially replaced natural sand (0 5 mm) in mortars with crumb
rubber (0 5 mm) at 0% 30%, by volume, by keeping constant the w/c ratio.
Results showed a reduction in the mechanical properties as the rubber sand content
increases. The reduction in the compressive strength was about 23%, 46%, 54%,
59%, 60% and 58% with the addition of 3%, 10%, 15%, 20%, 25% and 30% rubber
sand, respectively, while the reduction in the flexural strength was approximately
1%, 4%, 13%, 20%, 29% and 39%, respectively.
Pelisser et al. (2012) found a reduction in the compressive strength of mortars
where natural sand was replaced with recycled tyre rubber (0 2.4 mm) at 0%,
20%, 40% and 60%, by volume. The reduction in the compressive strength
increased by increasing the amount of rubber sand.
Pedro et al. (2013) reported a reduction in the mechanical properties by partially
replacing natural sand in mortars with shredded rubber (size 0 2 mm) at 5%, 10%
and 15%, by volume. The reduction of the compressive strength was 9%, 35% and
40% with the addition of 5%, 10% and 15% of rubber sand, respectively, after 28
days of curing. The reduction of the elasticity modulus was 11%, 28% and 31%
with the addition of 5%, 10% and 15% of rubber sand, respectively, after 28 days
of curing while it was 20%, 32% and 43%, respectively, after 90 days of curing.
Huang et al. (2013) investigated the mechanical properties of Engineered
Cement-based Composites (ECC) containing rubber (0 0.15 mm) as a partial
replacement of iron ore tailings (IOTs) (average size 0.135 mm) that were used as
aggregates at 0%, 10%, 20%, 30% and 40%, by volume. The reduction of the com-
pressive strength was about 63% and 74% with the addition of 10% and 40% of
rubber sand, respectively. The reduction of the tensile strength was about 28%,
30%, 34% and 36% with the addition of 10%, 20%, 30% and 40% of rubber sand,
respectively.
Gisbert et al. (2014) found a reduction in the mechanical properties of mortars
containing crumb rubber as partial replacement of natural sand, at different con-
tents. The reduction in the compressive strength was about 64%, 71%, 78% and
90% with the addition of 10%, 20%, 30% and 40% of coarse rubber sand, respec-
tively, while it was about 73%, 93%, 94% and 97% with the addition of fine rubber
sand. The reduction in the Young’s modulus was about 35%, 51%, 66%, 77% and
91% with the addition of 10%, 15%, 20%, 30% and 40% coarse crumb rubber
sand, respectively, while it was about 55%, 71%, 92%, 96% and 98%, respectively,
with the addition of fine rubber sand.

4.4.2.2 Replacement of natural aggregates with crumb rubber in
concrete (up to 15%)
Albano et al. (2005) reported a reduction in the compressive and flexural
strength of concrete where natural was replaced with recycled rubber from auto-
mobile tyre at 5% and 10%, by weight. The reduction in the compressive
strength was about 61% and 88% with the addition of 5% and 10% rubber sand