# Specific Gravity of Soils - PowerPoint PPT Presentation

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Specific Gravity of Soils. Specific Gravity. This number indicates how much heavier/lighter a material is than water. In soils, SG refers to the mass of solid matter of a given soil sample as compared to an equal volume of water. Specific Gravity.

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Specific Gravity of Soils

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## Specific Gravity of Soils

### Specific Gravity

• This number indicates how much heavier/lighter a material is than water.

• In soils, SG refers to the mass of solid matter of a given soil sample as compared to an equal volume of water.

### Specific Gravity

• For example: A material with SG of 2 is twice as heavy as water (2x 62.4 lbs/ft3 ) = 124.8 lbs/ft3

• Equation Form: SG = Ms/VsΥwater

• We use the SG of soils to calculate other engineering properties like the volume of solids in a sample….

• This leads to the phase diagram (like last class) and…

• S, n, e

### Specific Gravity

Soil Solids Water

W = 187.2 lbs W= 62.4 lbs

SG= 187.2/62.4 = 3.0

1 ft3

1 ft3

### General Ranges of SG For Soils

• Sand2.63 – 2.67

• Silt2.65-2.7

• Clay & Silty Clay2.67-2.9

• Organic Soils<2.0

### Procedures For Specific Gravity LabASTM D 854

See Chapter 3, Page 55 For Your Data Sheet

APPARATUS:

Ice

Heating Plate

Thermometer C

Evaporating Dish

Distilled Water

### Procedures (Method B)

• Dry specimens to constant mass in oven at 110 C.

• Select a 500 ml flask and record mass (g)

• Fill with distilled water to 500 ml line and record mass (g)

• Record temperature of water in degrees Celsius (T1).

• Pour 2/3 of water back into distilled container

• Weigh out 100g of sandy soil and transfer to flask

• Add distilled to 2/3 full and boil gently for 10 minutes

• Bring temperature back to T1 using cooling bucket w/ice.

• Add distilled to 500 ml line and record mass (g)

• Record mass of evaporating dish (g)

• Pour ALL sample into dish and dry to constant weight.

• Record mass of oven dried dish/sample.

• Complete calculations on data sheet, including correction for temperature …. SG is always reported at 20 C.

• See page 44 for correction factors.