SOIL COMPOSITION CE1303 – Engineering Material Properties -Ms Ikmalzatul CE1303 – Engineering Material Properties

The nature of Soil Soil is defined as a collection of mineral particles that was formed due to the weathering process of igneous rock and mixed with organic matter. The void between particles is filled with water and gas. Cementation among the particles is weak and is due to carbonation and oxidation between particles and or organic matter. Characteristics of soil in general are greatly influenced by the process of the soil formation. The structural arrangement of the particle may be loose, medium dense or dense depending on the packing of material.

Soil: A 3-Phase Material Air Water Solid

The Mineral Skeleton Solid Particles Volume Voids (air or water)

Three Phase Diagram Air Water Solid Idealization: Mineral Skeleton

Fully Saturated Soils Water Solid Mineral Skeleton Fully Saturated

Dry Soils Air Solid Dry Soil Mineral Skeleton

Partly Saturated Soils Solid Air Water Mineral Skeleton Partly Saturated Soils

Three Phase System Air Water Solid Volume Weight Va Wa~0 Vv Vw Ww WT VT Vs Ws Volume Weight

Weight Relationships Weight Components: Weight of Solids = Ws Weight of Water = Ww Weight of Air ~ 0

Volumetric Relationships Volume Components: Volume of Solids = Vs Volume of Water = Vw Volume of Air = Va Volume of Voids = Va + Vw = Vv

Volumetric Relationships Volume Components: Volume of Solids = Vs Volume of Water = Vw Volume of Air = Va Volume of Voids = Va + Vw = Vv

Specific Gravity Unit weight of Water, w w = 1.0 g/cm3 (strictly accurate at 4° C) w = 62.4 pcf w = 9.81 kN/m3

Specific Gravity Iron 7.86 Aluminum 2.55-2.80 Lead 11.34 Mercury 13.55 Granite 2.69 Marble 2.69 Quartz 2.60 Feldspar 2.54-2.62

Specific Gravity, Gs

Soil Unit weight (kN/m3) Bulk (or Total) Unit weight  = WT / VT Dry unit weight d = Ws / VT Buoyant (submerged) unit weight b = - w

Typical Unit weights

Example: Volumetric Ratios Determine void ratio, porosity and degree of saturation of a soil core sample Data: Weight of soil sample = 1013g Vol. of soil sample = 585.0cm3 Specific Gravity, Gs = 2.65 Dry weight of soil = 904.0g

Example Air Water Solid Wa~0 134.9cm3 W =1.00 243.9cm3 109.0g Volumes Weights

Example Air Water Solid 134.9cm3 W =1.00 243.9cm3 109.0cm3 585.0cm3 Volumes s =2.65 341.1cm3 109.0cm3 243.9cm3 134.9cm3 W =1.00

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