Proctor Compaction Test of Soil

The Proctor Compaction Test is performed to determine the relationship between the moisture content and dry density of soil.

 

Objective of Proctor Compaction Test

· Determine Maximum Dry Density (MDD)

· Determine Optimum Moisture Content (OMC)

· Control field compaction

· Improve soil stability

Types of Proctor Test

1. Standard Proctor Test

• Hammer Weight = 2.6 kg

• Drop Height = 310 mm

2. Modified Proctor Test

• Hammer Weight = 4.9 kg

• Drop Height = 450 mm

Apparatus Required

· Compaction mold

· Rammer (hammer)

· Weighing balance

· Oven

· Mixing tray

· Straight edge

Principle of Test

Soil is compacted at different moisture contents using a standard compactive effort. Dry density is calculated for each moisture content.

Test Procedure

1. Take dry soil sample

2. Add known quantity of water

3. Fill mold in layers

4. Compact each layer with specified blows

5. Remove and weigh compacted soil

6. Determine moisture content

7. Repeat for different moisture contents

8. Plot moisture content vs dry density curve

Formulae

Bulk Density (γ) = W / V

Dry Density (γd) = γ / (1 + w)

Example Calculation

Weight of compacted soil = 3600 g

Volume of mold = 2250 cc

Moisture content = 12%

Step 1: Bulk Density

γ = 3600 / 2250

γ = 1.60 g/cc

Step 2: Dry Density

γd = 1.60 / (1 + 0.12)

γd = 1.43 g/cc

Compaction Curve

The graph is plotted between moisture content and dry density. The peak point gives Maximum Dry Density (MDD) and Optimum Moisture Content (OMC).

Advantages

· Determines optimum moisture for compaction

· Improves soil strength

· Essential for quality control

Limitations

· Time-consuming

· Laboratory test may differ from field conditions

Standard Codes

IS 2720 Part 7 – Light Compaction Test

IS 2720 Part 8 – Heavy Compaction Test

ASTM D698

ASTM D1557

Applications

· Road construction

· Earth embankments

· Dam construction

· Foundation filling works