Civil Engineering Reference
In-Depth Information
R
100 µm
Note: R = rubber
13.5
Cracking bridging effect of rubber particles (Segre et al., 2006).
level of 5-10%, as for the latter case the reduction is between 15% and
30%. This behaviour maybe related to the very low adhesion between
the chipped rubber and the cement paste. one reason for this is the fact
that chipped rubber was prepared in laboratory with the help of scissors,
a procedure quite different from the rubber waste particles shredded by a
grinding process which favours a harsh surface. according to aiello and
Leuzzi (2010) when tyre shreds are used to replace fine aggregates a high
tensile (flexural) strength is obtained. A replacement of the volume of fine
aggregates (50% or 75%) leads to a strength reduction of only 5.8% and
7.30%. But if the same percentages were used to replace coarse aggregates
a 28.2% strength reduction took place (Table 13.4). The tensile strength
of rubber waste concrete is influenced by the characteristics of the rubber
aggregate. Some are associated with a tensile strength loss but others present
a high tensile strength. Future investigation should focus on the characteristics
of the rubber aggregates that enhance tensile strength.
Toughness
concrete composites containing tyre rubber waste are known for their high
toughness (li et al., 2004), having a high energy absorption capacity. aSTM
C1018-97 defines several toughness indexes (I
5
, i
10
and i
20
) as the area under
load-deflection curve of a flexural specimen for different times of deflection
after crack initiation related to area under the same curve up to the crack
initiation. Some authors (Balaha et al., 2007) report a 63.2% increase in the
