CCIL CCIL - Canadian Council of Independent Laboratories Soil Testing and Geotechnical Analysis Questions and Answers 3

Question 1

What minimum number of blows in the standard penetration test (SPT) over 12 inches of penetration defines a 'very dense' sand or gravel?

Accepted Answer

Greater than 50

Answer

Greater than 30

Answer

Greater than 40

Answer

Greater than 60

Question 2

In a laboratory permeability test using a falling-head permeameter, what soil property is being measured?

Accepted Answer

Hydraulic conductivity (coefficient of permeability)

Answer

Shear strength

Answer

Swelling potential

Answer

Compressibility index

Question 3

Which index property is used in the AASHTO system as the primary indicator of a soil's suitability for use as subgrade material?

Accepted Answer

Group Index (GI)

Answer

Plasticity Index (PI)

Answer

Liquid Limit (LL)

Answer

Compression Index (Cc)

Question 4

What does the California Bearing Ratio (CBR) test measure in pavement subgrade evaluation?

Accepted Answer

The resistance of a subgrade soil to penetration relative to a standard crushed stone

Answer

The compressive strength of undisturbed soil samples

Answer

The permeability of saturated subgrade soils

Answer

The swell potential of expansive subgrade clay

Question 5

During consolidation testing per ASTM D2435, what is the purpose of plotting the e-log p curve?

Accepted Answer

To determine the compression index (Cc) and preconsolidation pressure

Answer

To measure the coefficient of permeability at each load step

Answer

To establish the Atterberg limits from in-situ conditions

Answer

To classify the soil according to USCS criteria

Question 6

What correction factor must be applied to SPT N-values to account for hammer efficiency when comparing results across different equipment?

Accepted Answer

Energy ratio correction (ER) normalized to 60% efficiency (N60)

Answer

Overburden correction factor (CN) for depth

Answer

Rod length correction for shallow depths

Answer

Borehole diameter correction for large casings