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Proctor Compaction Test

for Maximum Dry Density

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What Is Compaction?

Compaction is the process of increasing the bulkdensityof a soil or aggregate by driving out air.

For any soil, at a given compactive effort, thedensity obtained depends on the moisturecontent.

For any soil, an optimum water content existsat which it will achieve its maximum density.

http://en.wikipedia.org/wiki/Bulk_densityhttp://en.wikipedia.org/wiki/Bulk_densityhttp://en.wikipedia.org/wiki/Bulk_densityhttp://en.wikipedia.org/wiki/Bulk_density

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Soils are compacted for the

following reasons:1. To increase strength and stability

2. To decrease permeability

3. To enhance resistance to erosion4. Decrease compressibility under load and

minimize settlement

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Common Equipment

Shown: Sheepsfoot Padfoot Vibratory Roller Grid Roller

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Definition: Maximum Dry Density

The peak dry unit weight is called the"maximum dry density.

The Optimum Water Content, wopt, is thewater content at the soils maximum drydensity.

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Dry Density Curve: Proctor Test

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How Does A Contractor Modify

Compaction in the Field?

Adjust Water Content

More Passes Thinner Lifts

Bigger Rollers

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Getting Back To The Proctor

Compaction Test

Test developed to helpspecify levels (%)compaction (1933).

Ralph R. Proctor firstdefined this standardcompaction test inEngineering News Record

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Proctor Compaction Procedure

Soil is air dried, pulverized& passed thru #4 sieve.

Separated into 4 to 6 samples.

Adjust the water content of each sample by addingwater.

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Using the proctor mould (1/30th cubic foot)place & compact soil in 3 layers.

Each layer should receive 25 drops of thecompaction hammer.

Proctor Compaction Procedure

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Proctor Compaction Procedure

After the last layer, use a straight edge totrim the excess soil leveling to the top ofthe mould.

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Proctor Compaction Procedure

Determine the weight of the mould withthe compacted moist soil.

Extrude from mould and collect a samplefor water content determination.

Repeat for each sample over a range ofmoisture contents.

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Proctor Compaction Procedure

After collecting allpertinent weights,calculate dry density

and plot vs. watercontent

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Typical Proctor Data

1 2 3 4 5 6 7 8 9

Mold (lbs)

Mold + Wet

Soil (lbs) Moist Soil (lbs)

Moist Unit Wt.

(pcf)

Mass of Can

(g)

Mass Can +

Moist Soil (g)

Mass of Can +

Dry Soil

Moisture

Content Dry Unit Wt.

9.31 13.23 3.92 117.60 61.00 273.50 249.70 0.13 104.43

9.20 13.60 4.40 132.00 61.00 280.00 249.20 0.16 113.44

9.31 13.52 4.21 126.30 61.00 242.90 214.90 0.18 106.86

9.30 13.34 4.04 121.20 61.00 306.70 265.60 0.20 100.93

9.20 13.25 4.05 121.50 61.00 222.60 190.20 0.25 97.14

9.31 13.16 3.85 115.50 61.00 212.20 178.10 0.29 89.45

(Line 3)/(1/30) (Line 4)/(1+Line 8)

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Graph from Proctor Data

80

85

90

95

100

105

110

115

120

0.00 0.10 0.20 0.30 0.40

D

ryDensity(pcf)

Water Content

Proctor Compaction Results

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Achieving Maximum

Compaction For any job requiring fill/compaction the engineer will

specify the compaction requirements:

ODOT Roadway Embankment Requirements:

Maximum Laboratory

Dry Weight

[lb/ft3]

Minimum Compaction

Requirements in Percent of

Laboratory Maximum

90 to 104.9 102

105 to 119.9 100

120 and higher 98

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Achieving Maximum

Compaction Since the maximum dry density is material

specific,

AND

Since material being hauled in maychange from truck to truck,

It is necessary to verify the maximum drydensity number for the material beingplaced.

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One-Point Proctor

Thus, the one-point proctor is used toverify the maximum dry density of soils inthe field.

One proctor test is done to determine thewet density vs. moisture content.

Then a family of curves is used todetermine the maximum dry density.

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ODOT Family of Curves

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Percent Compaction

Then, comparing the maximum drydensity to the ACTUAL density beingachieved (nuclear densometer), we can

calculate % compaction.

% Compaction = dry field/dry max