Page 132 - New Trends in Eco efficient and Recycled Concrete

106 New Trends in Eco-efficient and Recycled Concrete

4.5 Durability of concrete with crumb rubber

4.5.1 Water absorption porosity
Segre et al. (2004) investigated the water absorption of mortars containing 10% of
rubber sand (0.2 mm) as natural sand replacement, by weight. Results showed lower
percentage of water absorption with the addition of rubber sand.
Bignozzi and Sandrolini (2006) reported an increase in the water absorption of
SCC, where natural sand was replaced by rubber particles (size 0.5 2 mm) at up to
33.3%, by volume. The increase was 4% and 10.67% with the addition of 22.2%
and 33.3% of rubber sand, respectively.
Marques et al. (2008) observed a reduction of water absorption by replacing
12% of natural sand with crumb rubber (0 0.8 mm), by volume. The reduction
was about 5%, 7%, 23% and 6% at periods of 7, 28, 56 and 90 days,
respectively.
Turgut and Yesilata (2008) found an increase in the water absorption and poros-
ity of concrete blocks containing crumb rubber (0.075 4.75 mm) as natural sand
replacement at different contents, by volume. The increase in the water absorption
was about 25%, 52%, 64%, 95%, 112%, 123% and 143% with the addition of 10%,
20%, 30%, 40%, 50%, 60% and 70% of rubber sand, respectively, while the
increase of the porosity was approximately 21%, 42%, 47%, 65%, 69%, 65% and
73%, respectively.
Ganesan et al. (2012) found a reduction in the water permeability, water absorp-
tion and chloride ion penetration of concrete with partial replacement of natural
sand with crumb rubber (0 4.75 mm), by weight.
Pedro et al. (2013) found a 8.9% reduction in the water absorption of mortar spe-
cimens, after 28 days of curing, with the replacement of 5% of natural sand with
shredded rubber (0 2 mm), by volume. By increasing the rubber content (10%),
water absorption of concrete increased by 6.93%. The addition of 15% rubber
showed water absorption values comparable to those of the control specimen.
Experimental studies by Geso˘ glu et al. (2014) showed that the addition of 10%
and 20% of rubber sand with particle size of 4 mm in substitution of natural aggre-
gates reduced the permeability coefficient by 43% and 67%, respectively, while the
addition of rubber sand with particle size of 2 mm led to a reduction of 40% and
43%, respectively.
Bravo and de Brito (2012) observed an increase in the percentage of water
absorption with the addition of rubber aggregate made from used tyres as natural
sand replacement. The water absorption increased about 3%, 13% and 14% with
the addition of 5%, 10% and 15% of rubber sand, respectively. The addition of 5%
rubber sand caused a reduction in chloride diffusion, while the addition of 10% and
15% increased the chloride diffusion coefficient.
Mohammed et al. (2012) observed an increase in the water absorption by par-
tially replacing natural sand in hollow concrete blocks with crumb rubber
(0 0.6 mm) at up to 50%, by volume. The water absorption increased by increasing
rubber sand content.