Table 7 Soil indices and parameters for shale soil from other studies
Parameter | Nkporo shale | New Netim marl | Ekenkpon shale | Igumalea shale | Abakalikib shale | Pulaski county, Kentucky, USA shale soilc |
|---|---|---|---|---|---|---|
Fines (% passing sieve no 200) | 80.1 | 68.4 | 81.4 | 90 | 90–92 | 29–46f |
Plastic limit | 30.0 | 33.0 | 38.4 | 27 | 17–23 | 18–23 |
Liquid limit | 52.0 | 48.0 | 52.8 | 72 | 53–68 | 40-57 |
Plasticity index | 22.0 | 15.0 | 14.4 | 45 | 36–45 | 22-34 |
Liquidity indexe | −0.2 | −1.2 | −0.7 | −0.04 | 0.14-0.11 | 0.02 to −0.08 |
Compression index Ccd | 0.378 | 0.342 | 0.385 | 0.558 | 0.387–0.522 | 0.27–0.423 |
AASHTO classification | A-7-5(20) | A7-5(11) | A-7-5(15) | A-7-6 | A-7-6 | A-6(14) and A-7-6(25-27) |
USCS classification | OH | MH | OH | CH | CH | CL and CH |
Maximum dry density (Mg/m3) | 1620.0 | 2020.0 | 1700.0 | 1510 | 1830–1890 | N.L. |
Optimum moisture content (%) | 14.6 | 8.6 | 16.6 | 22 | 12.0–12.5 | N.L. |
CBR (%) (after 24 h soaking) | 26.8 | 20.6 | 7.0 | 0.68 | 38–55 | 3 |
Free swell (%) | N.D | N.D | N.D. | 50 | 48–52 | N.L. |
Specific gravity | N.D | N.D | N.D. | 2.55 | 2.42–2.56 | 2.56 -2.79 |
Colour | Black | Yellowish | Dark grey | Grey | Bluish–Brownish | Red |
Natural moisture content (%) | 26.3 | 15.6 | 27.8 | 25 | 22-28 | 17.5–25.8 |
pH | 2.27 | 6.97 | 4.28 | 6.83 | N.L. | N.L. |
Unconfined compressive strength (kN/m2) | 784.19 | 674.53 | 350.57 | 400 | N.L. | 100.4 |