Earthworks - Geotechnical Investigation and Design Tables - page 151

Table 12.22 Typical compaction test results (Hoerner, 1990).

Material Type of compaction test Optimum moisture Maximum dry density

content (%) (t/m 3 )

Heavy clay Standard (2.5 kg Hammer) 26 1.47

Modified (4.5kg Hammer) 18 1.87

Silty clay Standard 21 1.57

Modified 12 1.94

Sandy clay Standard 13 1.87

Modified 11 2.05

Silty gravelly clay Standard 17 1.74

Modified 11 1.92

Uniform sand Standard 17 1.69

Modified 12 1.84

Gravelly sand/sandy gravel Standard 8 2.06

Modified 8 2.15

Vibrating hammer 6 2.25

Clayey sandy gravel Standard 11 1.90

Vibrating hammer 9 2.00

Pulverised fuel ash Standard 25 1.28

Chalk Standard 20 1.56

Slag Standard 6 2.14

Burnt shale Standard 17 1.70

Modified 14 1.79

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The nuclear density gauge is a non destructive test. Direct Transmission or Back
Scatter Techniques used.

Table 12.23 Field compaction testing.

Equipment Sand cone Nuclear density gauge

Equipment cost Low High

Advantages

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Large sample

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Fast

Direct measurement Easy to redo

• •

•

Conventional approach

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More tests can be done

Disadvantages More procedural steps No sample

• •

Slow Radiation

• •

Less repeatable Moisture content results unreliable • •

Potential problems Vibration Presence of trenches and objects

within 1m affects results

• •

•

Calibration required for nuclear density gauge:
- Bi-annual manufacturers certificate.
- Quarterly checks using standard blocks.
- Material calibration as required.

•

For nuclear density moisture content: Every tenth test should be calibrated with
results of standard oven drying.