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Table 4-50: Compressive Strength of Concrete Mixtures
Mixture
No.
Fly Ash
[FA/(C+FA)],
(%)
Compressive Strength (psi)
3-day 7-day 14-day 28-day
Act. Avg. Act. Avg. Act. Avg. Act. Avg.
1115
1395
1760
2590 2535
40 43
980 1025 1485 1455 1810 1810 2460
990 1490 1855 2555
1000
1425
1960
2390 2385
50 43
965 970 1300 1380 1785 1850 2370
940 1420 1810 2395
805
1360
1695
2352 2340
60 43
850 830 1460 1370 1825 1760 2242
- 1300 1760 2427
Electrical Properties of Concrete Mixtures
The electrical properties of the concrete mixtures are shown in Tables 4-51
and Figure 4-28. The electrical resistivity of the air dried concrete prepared in
accordance with the invention is in the range of 1-128×10 3 ohm-cm. The air
dried conventional concrete typically has a resistivity of the order of 10 6 ohmcm,
with oven dried conventional concrete having a resistivity of the order of
10 11 ohm-cm. Therefore, it is apparent that the electrical resistivity of concrete
in accordance with the invention is less than the electrical resistivity of
conventional concrete. In other words, by incorporating high carbon fly ash
into a concrete mixture as in the present invention, a more electrically
conductive concrete is produced. The permeability of a concrete prepared with
high carbon fly ash in accordance with the present invention exceeds that of
air, indicating a greater capability to carry an electrical current. The use of fly
ash having greater levels of carbon would further decrease the resistivity of
the resulting concrete. In addition, the increased concentration of high carbon
fly ash in the composition will result in increased conductivity.
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Coal Combustion Products
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