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Table 1 Soil indices, moisture—density values, and classification for native soil

From: Occurrence of shale soils along the Calabar-Itu highway, Southeastern Nigeria and their implication for the subgrade construction

Sample No Geologic unit Natural moisture content (NMC) (%) Plastic limit (%) Liquid limit (%) Plasticity index (%) Liquidity index Sieve sizes in (mm) 4.75 2.36 1.18 0.6 0.425 0.3 0.15 0.075 pH AASHTO classification Unified soil classification system (USCS)
Maximum dry density (kg/m3) (MDD) Optimum moisture content, (%) (OMC) Percentage passing sieve no
  7 14 25 36 52 100 200
I Nkporo Shale 26.3 30.0 52.0 22.0 −0.2 1620.0 14.6 100. 93.9 93.9 89.8 88.4 87.3 85.5 80.1 2.27 A-7-5(20) OH
I New Netim Marl 15.6 33.0 48.0 15.0 −1.2 2020.0 8.6 94.7 84.0 84.0 79.9 78.0 76.2 72.6 68.4 6.97 A-7-5(11) MH
I Ekenkpon Shale 27.8 38.4 52.8 14.4 −0.7 1700.0 16.6 94.0 89.0 89.0 86.6 85.8 84.8 83.0 81.4 4.28 A-7-5(15) OH
II Ekenkpon Shale II 26.2 36.5 51.5 15.1 −0.7 1680.0 18.5 100. 99.2 99.2 97.2 95.8 94.6 91.8 90.0   A-7-5(18) OH