CE 322 – A1
Standard Proctor Compaction Test
and
Modified Proctor Compaction Test
Lab Performed by Group #3
Hanna Hoffman, Bryant Nakagawa, Emery Norwood, and Catherine Tran
Standard Proctor Compaction Test Performed on 10/4/2019
Modified Proctor Compaction Test Performed on 10/11/2019
Lab Report Prepared by Catherine Tran
Lab Report Submitted on 10/18/2019
Compaction Tests Tran
Contents
Introduction ............................................................................................................................................................ 2
Procedure ................................................................................................................................................................. 2
Calculations ............................................................................................................................................................. 3
Results ....................................................................................................................................................................... 4
Discussion ................................................................................................................................................................ 4
References ............................................................................................................................................................... 5
Appendix I ................................................................................................................................................................ 5
Introduction
The Proctor Test is used to determine the compaction of different types of soil and the
properties of soil with a change in moisture content. This test examines the relationship
between Dry Density and Moisture Content.
Procedure
Standard Proctor Compaction Test
Take about 10 lbs9 of fine soil, add water to bring its water content to about 5% below the
estimated optimum moisture content. Then mix it thoroughly. Clean the mold, measure its
diameter & height & weigh it without the collar. Fit the collar & compact the moist soil in
three equal layers by the rammer with 25 blows to each layer. Weigh the compacted soil
with the mold. Take a sample a measure the moist weight. After drying the sample,
measure the dry weight.
Modified Proctor Compaction Test
ASTM provides a modified method to conduct the Standard Proctor Compaction Test in
ASTM Standard D-1557. With 10 pounds of fine soil, hammering a similar mold with a
volume of 1/30 cubic feet. The soil is compacted in five equal layers, 25 blows per layer.
The compaction energy for this type of test is 56,250 feet pound/cubic feet. A comparison
of dry unit weight versus moisture content obtained from the standard and modified
proctor compaction tests show that the maximum dry unit weight of compaction increases
as the compacting energy increases. The optimum moisture content decreases with the
increase in the energy of compaction.
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Compaction Tests Tran
Calculations
𝑀𝑎𝑠𝑠 𝑜𝑓 𝑆𝑜𝑖𝑙 (𝑀𝑆 ) = 𝑀𝑎𝑠𝑠 𝑜𝑓 𝑀𝑜𝑙𝑑 𝑎𝑛𝑑 𝑆𝑜𝑖𝑙 − 𝑀𝑎𝑠𝑠 𝑜𝑓 𝑀𝑜𝑙𝑑 Equation 1
Example:
MS = 13.32 lb — 9.44 lb
MS = 3.88 lb
𝑀
𝑀𝑜𝑖𝑠𝑡 𝑈𝑛𝑖𝑡 𝑊𝑒𝑖𝑔ℎ𝑡 (γ) = 𝑉𝑠 Equation 2
Where
MS = Mass of Soil
V = Volume of Mold
Example:
MS = 3.88 lb
V = 1/30 lb3
γ = (3.88 lb)/(0.333 lb3) = 116.4 lb/ft3
𝑀𝑀
𝑀𝑜𝑖𝑠𝑡𝑢𝑟𝑒 𝐶𝑜𝑛𝑡𝑒𝑛𝑡 (𝑤%) = × 100 Equation 3
𝑀𝐷
Where
MM = Mass of Moisture = Mass of Moisture Mass – Mass of Dry Mass
MD = Mass of Dry Soil = Mass of Dry Soil + Can – Mass of Can
MM = 96.0 g – 87.0 g = 9.0 g
MD = 87.0 g – 20.5 g = 66.5 g
9.0 𝑔
w = 66.5 𝑔 × 100 = 13.5%
𝛾
𝐷𝑟𝑦 𝑈𝑛𝑖𝑡 𝑊𝑒𝑖𝑔ℎ𝑡 (𝛾𝐷 ) = 1+(𝑤%/100) Equation 4
Where
γ = Moist unit weight
w% = Moisture content
γ = 116.4 lb/ft3
w%/100 = 0.135
116.4
γD = 1+0.135 = 102.5 lb/ft3
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Compaction Tests Tran
Results
Modified Proctor Test
110.0
108.0 Maximum Dry Unit Weight:
Dry Unit Weight (lb/ft3)
109.0 lb/ft3
106.0
104.0
102.0
100.0
98.0
96.0 Optimum Moisture Content: 17.0 %
94.0
0.0 5.0 10.0 15.0 20.0 25.0 30.0
Moisture Content (w %)
Modified Proctor Test
119.0
118.0 Maximum Dry Unit Weight:
118.0 lb/ft3
Dry Unit Weight (lb/ft3)
117.0
116.0
115.0
114.0
113.0
112.0
111.0
110.0 Optimum Moisture Content: 10.0 %
109.0
0.0 5.0 10.0 15.0 20.0 25.0
Moisture Content (w%)
Discussion
Both the standard and modified proctor compaction tests call for the addition of water to
dry soil to obtain different moisture contents to compact with the proctor hammers. Using
the dry unit weight and moisture content, a chart was created and the maximum dry unit
weight and optimum moisture content was found from the plotted curve. The modified test
was like the standard test except the modified proctor hammer is 10 pounds compared to
the standard 5.5 pounds standard proctor hammer. The number of layers and blows/layer
also differed, changing how compacted the soil was.
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Compaction Tests Tran
The standard proctor compaction results were 17% for the optimum moisture content and
109 lb/ft2 optimum dry unit weight. The modified proctor compaction results were 10%
and 118 lb/ft2. When comparing the curves from each test, the modified proctor
compaction test yielded a higher unit weight since this modified test had increased
compacting energy.
References
Das, Braja M. (2016) Soil Mechanics Laboratory Manual. New York, NY: Oxford
University Press
Appendix I
Data
Standard Proctor Compaction Test
1 2 3 4
Mold + Base (lb) 9.44 9.44 9.44 9.44
Mold + Base + Moist Soil (lb) 13.32 13.66 13.70 13.46
Moist Soil (lb) 3.88 4.22 4.26 4.02
Moist Unit Weight (lb/ft3) 116.40 126.60 127.80 120.60
Can (g) 20.5 21.0 20.5 20.5
Can + Moist Soil (g) 96.0 99.5 122.5 83.0
Can + Dry Soil (g) 87.0 88.5 105.0 70.0
Moisture Content (%) 13.5 16.3 20.7 26.3
Dry Unit Weight (lb/ft3) 102.5 108.9 105.9 95.5
Modified Proctor Compaction Test
1 2 3 4
Mold + Base (lb) 9.48 9.48 9.48 9.48
Mold + Base + Moist Soil (lb) 13.40 13.82 13.94 14.08
Moist Soil (lb) 3.92 4.34 4.46 4.60
Moist Unit Weight (lb/ft3) 117.60 130.20 133.80 138.00
Can (g) 21.0 21.0 21.0 21.0
Can + Moist Soil (g) 85.0 97.0 109.0 108.0
Can + Dry Soil (g) 81.0 90.0 94.0 97.0
Moisture Content (%) 6.7 10.1 20.5 14.5
Dry Unit Weight (lb/ft3) 110.3 118.2 111.0 120.6
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