Proctor Compaction Test for Proctor Compaction Test for Maximum Dry DensityMaximum Dry Density
What Is Compaction?What Is Compaction?
Compaction is the process of increasing the Compaction is the process of increasing the bulk density of a soil or aggregate by driving of a soil or aggregate by driving out air. out air.
For any soil, at a given compactive effort, the For any soil, at a given compactive effort, the density obtained depends on the moisture density obtained depends on the moisture content. content.
For any soil, an “optimum water content” For any soil, an “optimum water content” exists at which it will achieve it’s maximum exists at which it will achieve it’s maximum density.density.
Soils are compacted for the Soils are compacted for the following reasons:following reasons:1.1. To increase strength and stabilityTo increase strength and stability
2.2. To decrease permeabilityTo decrease permeability
3.3. To enhance resistance to erosionTo enhance resistance to erosion
4.4. Decrease compressibility under load Decrease compressibility under load and minimize settlementand minimize settlement
Common EquipmentCommon Equipment
Shown:Shown: SheepsfootSheepsfoot PadfootPadfoot Vibratory RollerVibratory Roller Grid RollerGrid Roller
Dynamic Compaction: Dynamic Compaction: Profile of OverlapProfile of Overlap
Definition: Maximum Dry Density Definition: Maximum Dry Density
The peak dry unit weight is called the The peak dry unit weight is called the "maximum dry density”."maximum dry density”.
The Optimum Water Content, wThe Optimum Water Content, woptopt, is , is the water content at the soil’s the water content at the soil’s maximum dry density. maximum dry density.
Achieving Maximum Compaction Achieving Maximum Compaction In The FieldIn The Field
Proctor Compaction Test determines the optimum Proctor Compaction Test determines the optimum water content and maximum dry density of for a water content and maximum dry density of for a soil.soil.
A required range for moisture is often specified A required range for moisture is often specified by the engineer:by the engineer: Ie, 3% below and 2% above optimum. Ie, 3% below and 2% above optimum.
For example, if optimum water content is 16%, For example, if optimum water content is 16%, the acceptable range would be from 13% to 18%. the acceptable range would be from 13% to 18%.
Percent compaction is also specified:Percent compaction is also specified: Meaning “required percentage of max dry density”Meaning “required percentage of max dry density”
% Compaction = % Compaction = ρρdry field dry field //ρρdry maxdry max
Dry Density Curve: Proctor Dry Density Curve: Proctor TestTest
How Does A Contractor Modify How Does A Contractor Modify Compaction in the Field?Compaction in the Field?
Adjust Water Content Adjust Water Content More Passes More Passes Thinner Lifts Thinner Lifts Bigger Rollers Bigger Rollers
Sand Cone TestSand Cone Test
Nuclear DensometerNuclear Densometer
How Do We Determine How Do We Determine Actual Field Density?Actual Field Density?
Getting Back To The Proctor Getting Back To The Proctor Compaction TestCompaction Test
Test developed to help Test developed to help specify levels (%) specify levels (%) compaction (1933).compaction (1933).
Ralph R. Proctor first Ralph R. Proctor first defined this standard defined this standard compaction test in compaction test in Engineering News Engineering News RecordRecord
Proctor Compaction ProcedureProctor Compaction Procedure
Soil is air dried, pulverized Soil is air dried, pulverized & passed thru #4 sieve.& passed thru #4 sieve.
Separated into 4 to 6 samples.Separated into 4 to 6 samples.
Adjust the water content of each sample by Adjust the water content of each sample by adding water.adding water.
Using the proctor mould (1/30th cubic Using the proctor mould (1/30th cubic foot) place & compact soil in 3 layers.foot) place & compact soil in 3 layers.
Each layer should receive 25 drops of the Each layer should receive 25 drops of the compaction hammer.compaction hammer.
Proctor Compaction ProcedureProctor Compaction Procedure
Proctor Compaction ProcedureProctor Compaction Procedure
After the last layer, use a straight edge to trim the excess soil leveling to the top of the mould.
Proctor Compaction ProcedureProctor Compaction Procedure
Determine the weight of the mould with the compacted moist soil.
Extrude from mould and collect a sample for water content determination.
Repeat for each sample over a range of moisture contents.
Proctor Compaction ProcedureProctor Compaction Procedure
After collecting all After collecting all pertinent weights, pertinent weights, calculate dry calculate dry density and plot vs. density and plot vs. water contentwater content
Typical Proctor DataTypical 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)
Graph from Proctor DataGraph from Proctor Data
Achieving Maximum Achieving Maximum CompactionCompaction
For any job requiring fill/compaction the engineer For any job requiring fill/compaction the engineer will specify the compaction requirements:will specify the compaction requirements:
ODOT Roadway Embankment ODOT Roadway Embankment Requirements:Requirements:
Maximum LaboratoryDry Weight
[lb/ft3 ]
Minimum CompactionRequirements in Percent of
Laboratory Maximum90 to 104.9 102
105 to 119.9 100
120 and higher 98
Achieving Maximum Achieving Maximum CompactionCompaction
Since the maximum dry density is Since the maximum dry density is material specific,material specific,
ANDAND Since material being hauled in may Since material being hauled in may
change from truck to truck,change from truck to truck, It is necessary to verify the It is necessary to verify the
maximum dry density number for the maximum dry density number for the material being placed.material being placed.
One-Point ProctorOne-Point Proctor
Thus, the one-point proctor is used to Thus, the one-point proctor is used to verify the maximum dry density of verify the maximum dry density of soils in the field.soils in the field.
One proctor test is done to One proctor test is done to determine the wet density vs. determine the wet density vs. moisture content.moisture content.
Then a “family of curves” is used to Then a “family of curves” is used to determine the maximum dry density.determine the maximum dry density.
ODOT Family of CurvesODOT Family of Curves
Percent CompactionPercent Compaction
Then, comparing the maximum dry Then, comparing the maximum dry density to the ACTUAL density being density to the ACTUAL density being achieved (nuclear densometer), we achieved (nuclear densometer), we can calculate % compaction.can calculate % compaction.
% Compaction = % Compaction = ρρdry field dry field //ρρdry maxdry max
