Civil Engineering Reference
In-Depth Information
Table 7.39
Maximum content of impurities allowed (Vazquez et al.
2006
)
Impurities
Maximum allowed ratio (%)
Ceramic materials
5
Lightweight materials
1
Bituminous materials
1
Other materials
a
1
a
Glass, plastics, metals, among others
harsh conditions such as alkali-silica attack, sulphate attack, fire, among others
and some special concrete with fibres or polymers.
Recycled Aggregates
This recommendation allows the use of recycle aggregates with size C4 mm and
the replacement of up to 5 % of coarse NA by RA. The content of clay particles
should not exceed 0.6 % in the aggregates and 0.15 % in the NA. The maximum
levels of impurities allowed in the RA are presented in Table
7.39
.
Regarding chlorides content, this recommendation suggests considering the
total chlorides content instead of the water-soluble content as recommended in
various other specifications and also in EHE. However, the maximum value of
chlorides allowed must be the same as suggested in EHE. This choice is due to the
fact that there may be combined chlorides that, in certain circumstances, may be
reactive chlorides and attack the reinforcement. Table
7.40
shows the require-
ments for aggregates according to the EHE standard.
Regarding the allowed maximum water absorption, it is limited to 7 % for RA
and 4.5 % for natural coarse aggregates when the replacement ratio of NA by RA
is no more than 20 %. For higher replacement ratios, the combination of natural
and recycled coarse aggregates must have water absorption below 5 %. To esti-
mate the water absorption capacity, it is recommended to perform tests to deter-
mine the water absorption at 10 min, which should be less than 5.5 % for
replacement rates up to 20 %. The wear resistance of the RA should be similar to
that of the NA, i.e. a coefficient of Los Angeles not exceeding 40 %.
Table 7.40
Specification for aggregates in the Spanish standard (Vazquez et al.
2006
)
Properties
Specified amount
Total fine (\63 lm) content (%)
B1
Shape index
C0.2
Water absorption (%)
B5
Los Angeles coefficient (%)
B40
Water soluble chlorides (%)
B0.05
Acid soluble sulphates (%)
B0.08
Lightweight particles (%)
B1
Clay content (%)
B0.25
