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11 Cards in this Set
- Front
- Back
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What is Soil Compaction? |
Compaction results in rearrangment of soil particles for volume reduction |
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Effects of Compaction on Soil |
- Increases strength and improves stability - Reduces compressibility - Improves resilient modulus - Decreases permeability - Decreases frost effects |
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How is Soil Compacted? |
- Loose soil is spread into a "loose lift" of specified thickness - A compactor makes repeated passes over the "loose lift" to densify the soil |
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Types of compactors |
- Smooth drum roller - Padfoot/smooth drum combination roller - Pneumatic (rubber tire) roller - Sheepsfoot roller |
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Field Compaction methods |
Coarse-grained soils: - Vibratory methods (smooth drum) - Compaction occurs from the top - down Fine-grained soils: - Sheepsfoot rollers work well - Compaction occurs from the botton - up |
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Proctor Compaction Test |
Used to obtain the moisture-unit weight relationship |
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Proctor Compaction Test Specifics |
- 4 in diameter mold - volume = 1/30 ft3 - compact soil in mold in 3 layers - Using a 5.5 lb hammer, dropping 12 inches - apply 25 blows per layer Repeat process at different water contents |
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Modified Proctor test |
Involves more compactive effort by increasing hammer weight and drop height |
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End Result Compaction Specifications |
Engineer Specifies: - Minimum relative compaction - Compaction water content range - Maximum lift thickness - Maximum size of material to compact |
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Method Compaction Specifications |
Engineer Specifies: - Type & size of equipment - Lift thickness - Number of passes - Materials to use |
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Field Verification |
- Sand Cone test - Balloon test - Nuclear gage - Controls and Sensors on the compactor |
