Civil Engineering Reference
In-Depth Information
Table 5.5
Influence of various parameters of RCA on concrete density (Lopez-Gayarre et al.
2009)
Parameters
Levels
Density
Parameters
Levels
Density
Influence
Variation
(%)
Influence
Variation
(%)
Type of
aggregate
OV
XXX
Declassified
content (%)
0
MA
1
5
Replacement
ratio (%)
0
XXX
10
20
-1.2
Base concrete
(MPa)
35
50
-2.8
25
100
-5.2
Targeted slump
(cm)
8
X \1
Type of sieve
curves
CF
X
-1
13
SR
D CR \0.5
XXX Very influential; X Slightly influential; OV and NA RCA with different properties (OV has
higher adhered mortar and declassified contents, los Angeles coefficient and water absorption
capacity than NA); CF Fine sieve continuous curve; CC Coarse sieve continuous curve; D Dis-
continuous curve; SR Coarse natural aggregate replaced by identical volume of RCA; CR Fine
natural aggregate replaced by identical volume of declassified content in RCA and natural coarse
aggregate replaced by coarse fraction present in RCA
CC
Replacement
criteria
Table 5.6
Air-content of concrete mix containing pre-saturated recycled aggregate
Reference
Type of aggregate
(replacement ratio)
Air-content
(%)
Comment
Sagoe-Crentsil et al.
(
2001
)
Coarse basalt
2.4
Coarse recycled (100 %)
2.4
1.8
slag cement as binder
2.3
5 % more cement
Katz (
2003
)
Normal
1.3
White Portland cement as
binder
Recycled concrete
(coarse ? fine)
5.4 (1 day)
4.1 (7 day)
5.0 (28 day)
Recycled concrete
(coarse ? fine)
4.8 (1 day)
5.4 (7 day)
5.6 (28 day)
Ordinary Portland cement
as binder
Rustom et al. (
2007
)
Normal
1.0-2.0
Ordinary Portland cement
as binder
Recycled concrete
1.8-3.3
(Fig.
5.3
). Their results also indicated lower air-content in the mix containing
better quality RCA aggregate (MA) than that of inferior one (OV). The quality of
the two aggregates used in this investigation is presented in Table
5.7
.
Katz (
2003
) observed higher air-content in concrete containing RCA aggregate
than in concrete containing natural aggregate, when the air-content was measured
by a gravimetric method. The air-content of the aggregate was also measured
in the method. However, the air-content of concrete containing RCA was not
affected by the crushing age of the original hardened concrete. On the other hand,
