Civil Engineering Reference
In-Depth Information
Fig. 4.7 Flexural strength of concrete with CBA aggregate (M1, M2, M3, M4, M5 in Fig.
4.7
b
represents concrete with CBA replacing 0, 20, 30, 40 and 50% by weight of natural sand). a Kim
and Lee
2011
; b Aggarwal et al.
2007
4.2.2.3 Flexural Strength
Some authors observed a significant reduction in the flexural strength of concrete
due to the incorporation of CBA, as well as to increasing CBA content, even
though the effect observed in compressive strength behaviour was insignificant
(Kim and Lee
2011
, Agarwal et al.
2007
). Some experimental results are presented
in Fig.
4.7
. On the other hand, Triches et al. (
2007
) observed an increase in
flexural strength of roller compacted concrete (RCC) due to the addition of CBA as
partial substitution of natural sand because of the pozzolanic activity of CBA as
well as improvements of aggregate arrangement in the concrete matrix. Kuruma
et al. (
2009
) observed higher flexural strengths for concrete prepared by replacing
50 % (by weight) of natural sand with fine CBA.
Ghafoori and Bacholc (
1996
) reported that conventional concrete exhibited
higher flexural strength at low content of cement than concrete with CBA fine
aggregate. However, they were able to reduce this difference by increasing cement
content in concrete mix as well as by adding chemical admixture in the concrete mix
Table 4.1 Flexural strength of concrete (psi) with natural sand and CBA as fine aggregates
(Ghafoori and Bucholc
1996
)
Cement content in concrete (lb/yd
3
)
Cement content in concrete (lb/yd
3
)
Curing age (day)
500
600
700
800
500
600
700
800
Natural sand (C)
CBA aggregate (BA)
7
505
646
716
818
376
501
641
752
28
595
722
797
881
481
622
748
916
90
688
830
945
985
573
707
815
925
CBA aggregate ? 12.5 oz
ADM/100 lb cement (ADM1)
CBA aggregate ? 25.0 oz
ADM/100 lb cement (ADM2)
7
469
588
743
809
452
675
809
951
28
674
788
840
926
636
830
967
1054
90
711
826
904
963
721
882
1021
1137
