2.2. SOIL COMPACTION (MOISTURE-DENSITY RELATIONSHIP)

Determine optimum water content of soil

Find maximum dry density

Check soil moisture sensitivity

Design Requirement:

Strength - Slope stability

Compressibility - Settlement control

Permeability - Dam core (build up low permeable zone)

2.2.1. LABORATORY SOIL COMPACTION

General Procedure

① Prepare specimen.

② Add water.

③ Compact in specified mold with specified compaction energy.

④ measured.

⑤ measured.

⑥ Repeat 1-5 for various .

Test Results: Moisture-Density (Unit Weight) Relationship

=

Standard and Modified Proctor

AASHTO T99 or ASTM D 698 : Standard Proctor Test

-most state highway agencies

AASHTO T180 or ASTM D 1557 : Modified Proctor Test

-airports

2.2.2. FIELD COMPACTION

Highway Off-Ramp Compaction

Roller Compactors

Smooth Wheeled Roller

Compacts effectively only to 200-300 mm; therefore, place the soil in

shallow layers (lifts)

Vibrating Plates

For compacting very small areas

Effective for granular soils

Sheepsfoot Roller

Provides kneading action; “walks out” after compaction

Very effective on clays

Similar to padded drum roller, tamping-foot roller

Impact Roller

Provides deeper (2-3 m) compaction

e.g., air field