Civil Engineering Reference
In-Depth Information
Fig. 5.11 CS of concrete
containing coarse and fine
coarse recycled aggregates
and of reference concrete
(Corinaldesi
2010
)
Fig. 5.12 CS of concrete (H,
M, L: Original high, medium
and low strength concrete; H/
H, M/L: high and medium
strength concrete containing
RCA produced from H and L
concrete, respectively, etc.)
(Hansen and Boegh
1985
)
60
40
20
0
H H/H H/M H/L
M M/H M/M M/L
L
L/H L/M L/L
Concrete Type
aggregate size. They observed higher CS in concrete containing RCA than in
concrete containing NA provided that the CS of concrete from which RCA was
generated that was higher than that of the concrete containing NA used for
comparison purposes. Hansen and Narud (
1983
) observed lower CS in concrete
containing RCA than in control concrete, when the CS of control concrete
exceeded the CS of concrete from which RCA was generated. The variations of CS
of RCAC and control concrete containing NA were due to the bond between
cement mortar and coarse aggregate; low bond gave a poor quality RCA and hence
lower strength RCAC.
Nagataki and Iida (
2001
) also observed the dependence of CS on the strength of
the source concrete; the CS is higher for RCAC produced from higher CS concrete
than for that originated from lower CS concrete. Poon et al. (
2004a
) reported that
the CS of RCAC originated from high CS concrete is higher than the RCAC
originated from normal CS concrete due to formation of a denser microstructure in
ITZ in the former one than in the latter one and also a higher aggregate strength of
RCA originated from the high CS concrete than that of the RCA originated from
normal CS concrete. The ITZ of concrete containing RCA originated from high CS
concrete was denser than that of natural aggregate concrete too. Although the CS
