1. Proctor Compaction Test for Maximum Dry Density

2. What Is Compaction?
Compaction is the process of increasing the bulk density of a soil or aggregate by driving out air.
For any soil, at a given compactive effort, the density obtained depends on the moisture content.
For any soil, an “optimum water content” exists at which it will achieve it’s maximum density.

3. Soils are compacted for the following reasons:
To increase strength and stability
To decrease permeability
To enhance resistance to erosion
Decrease compressibility under load and minimize settlement

4. Common Equipment Shown: Sheepsfoot Padfoot Vibratory Roller
Grid Roller

5. Dynamic Compaction: Profile of Overlap

6. Definition: Maximum Dry Density
The peak dry unit weight is called the "maximum dry density”.
The Optimum Water Content, wopt, is the water content at the soil’s maximum dry density.

7. Achieving Maximum Compaction In The Field
Proctor Compaction Test determines the optimum water content and maximum dry density of for a soil.
A required range for moisture is often specified by the engineer:
Ie, 3% below and 2% above optimum.
For example, if optimum water content is 16%, the acceptable range would be from 13% to 18%.
Percent compaction is also specified:
Meaning “required percentage of max dry density”
% Compaction = ρdry field /ρdry max

8. Dry Density Curve: Proctor Test

9. How Does A Contractor Modify Compaction in the Field?
Adjust Water Content
More Passes
Thinner Lifts
Bigger Rollers

10. How Do We Determine Actual Field Density?
Sand Cone Test
Nuclear Densometer

11. Getting Back To The Proctor Compaction Test
Test developed to help specify levels (%) compaction (1933).
Ralph R. Proctor first defined this standard compaction test in Engineering News Record

12. 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 adding water.

13. Proctor Compaction Procedure
Using the proctor mould (1/30th cubic foot) place & compact soil in 3 layers.
Each layer should receive 25 drops of the compaction hammer.

14. Proctor Compaction Procedure
After the last layer, use a straight edge to trim the excess soil leveling to the top of the mould.

15. Proctor 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.

16. Proctor Compaction Procedure
After collecting all pertinent weights, calculate dry density and plot vs. water content

17. Mass Can + Moist Soil (g)
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
280.00
249.20
0.16
113.44
13.52
4.21
126.30
242.90
214.90
0.18
106.86
9.30
13.34
4.04
121.20
306.70
265.60
0.20
100.93
13.25
4.05
121.50
222.60
190.20
0.25
97.14
13.16
3.85
115.50
212.20
178.10
0.29
89.45
(Line 3)/(1/30)
(Line 4)/(1+Line 8)

18. Graph from Proctor Data

19. 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

20. Achieving Maximum Compaction
Since the maximum dry density is material specific,
AND
Since material being hauled in may change from truck to truck,
It is necessary to verify the maximum dry density number for the material being placed.

21. One-Point Proctor
Thus, the one-point proctor is used to verify the maximum dry density of soils in the field.
One proctor test is done to determine the wet density vs. moisture content.
Then a “family of curves” is used to determine the maximum dry density.

22. ODOT Family of Curves

23. Percent Compaction
Then, comparing the maximum dry density to the ACTUAL density being achieved (nuclear densometer), we can calculate % compaction.
% Compaction = ρdry field /ρdry max