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TECHNICAL PAPER

50 46.7 80
71
42.4 32.5 37 41.5 34.6 38.3 70 63.4 66.7 53.2 57.8 52 55.5
Compressive strength (MPa) 30 24.2 22.11 21.2 31.4 Compressive strength (MPa) 50 36.5 29.1 50.7 30.5 49.2
40
36
60
40
20
30
20
10

0
0 10
SCC SCCFRA50 SCCFRA100 HSSCC HSSCCFRA50 HSSCCFRA100
7 days 28 days 56 days 90 days 7 days 28 days 56 days 90 days
Figure 11(a): Results of compressive strength variation for SCC and HSSCC mixes.
Compressive strength ratio 0.7 0.58 0.6 0.54 0.62 0.58 0.55 0.580.55 0.62 0.59 variations in compressive strength to the inconsistent quality
0.8
20 per cent (HSSCCFRA50). Additionally, we attribute these
0.68
0.69
0.68
0.56
0.6
0.55
0.52
0.52
0.51
and high water absorption of RA on bonding and their hydration
0.5
rates. In addition, although fly ash and GGBS have somewhat
0.4
different effects on later age strength, the lower binder cement
0.3
0.2
ratio in the high strength mix further exaggerates these effects
0.1
0
period.
SCCFRA50 SCCFRA100 HSSCCFRA50 HSSCCFRA100 Split tensile strength results
SCC HSSCC to cause uneven strength development as a function of curing
RFA replacements depicted values similar to the compression
MIX ID The results from the split tensile test with the adoption of
7days/28 days 7days/56 days 7days/90 days strength test (Figure 12). The attached mortar, the soft and
Figure 11(b): Plot of Compressive Strength ratios permeable nature of RFA, and the accumulation of excess water
generate a gap between the aggregate and the cement paste
crushing process causing many pores and micro cracks and to which results in lesser strength with greater replacement levels.
the RFA’s low quality and density.
In Figure 12(a) the results depicted a decline of 12.5 % at the
In Figure 11(a), the maximum strength loss with curing is age of 90 days with full replacement in standard strength
18.4 % for the standard grade (SCCFRA100) and for the high mixes and 17.6 % for high-strength mixes when compared to
strength grade (HSSCCFRA100) for the SCCFRA100 and the conventional mixes. The decrease in tensile strength was less for
HSSCCFRA100 relative to the SCC and HSSCC, respectively, partial replacement of FRA50 compared with full replacement
[27]
at 90 days of curing. The declines are 11.2 % (SCCFRA50) and FRA100 mixes. .
6 8
5.25 6.8
4.7 7 6.2
5 3.78 3.45 4.6 6 5.43 4.64 5.45 5.88 5.2 5.6
Tensile strength (MPa) 4 3 2.3 3.4 2.15 3.1 2 2.9 3.37 Tensile strength (MPa) 5 4 3 3.6 3.15 3.08 4.4

1 2 2
1
0 0
SCC SCCFRA50 SCCFRA100 HSSCC HSSCCFRA50 HSSCCFRA100
7 days 28 days 56 days 90 days 7 days 28 days 56 days 90 days
Figure 12(a): Results of Tensile strength variation for SCC and HSSCC mixes

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