1. DIFFENTIATION BETWEEN PROCTOR COMPACTION TEST AND
MODIFIED PROCTOR COMPACTION TEST
AND
EMPERICAL RELATION FOR COMPACTION TEST
Prepared by:-
Samyog Khanal (13/077)
Central Department of Geology
Tribhuvan University
Engineering Geology
Samyogkhanal2017@gmail.com
Submitted to:-
Ranjan Kumar Dahal, PhD,
PostDoc, M.ASCE
Associate Professor
Central Department of Geology
Tribhuvan University
Kirtipur, Kathmandu, Nepal
2. 1) Introduction
• In general, compaction is the process of densifying soil by removing
air, which needs mechanical energy.
• The dry unit weight of a soil is used to determine the degree of
compaction.
• As the moisture content rises, the dry unit weight after initial
compaction rises.
• The optimum moisture content is typically defined as the moisture
content at which the greatest dry unit weight is achieved.
• The Proctor compaction test is the laboratory procedure often used to
determine the ideal moisture content and maximum dry unit weight of
compaction (Proctor, 1933)
3. Figure 1:- Principles of Compaction
At a moisture content w=0,
γ = γd (w=0) = γ1
At w= w1, γ = γ2
The dry unit weight at this
moisture content is
γd(w=w1) = γd(w = 0)+ ∆γd
Where
γ = moist unit weight
γd= dry unit weight
4. 2) Importance of Compaction
Compaction
Increases the
Strength of soil
Increases the
bearing capacity of
foundation
Increases the
Strength of soil
Increases the
Stability of slope
of embankments
5. 3) Discussion
a) Type of Compaction test
• Standard Proctor Compaction test (SPCT)
The procedure for the standard Proctor test is elaborated in ASTM Test
Designation D-698 (ASTM, 2007) and AASHTO Test Designation T-99
(AASHTO, 1982).
• Modified Proctor Compaction test (MPCT)
This is revised version of Standard Proctor Compaction test sometimes is referred to
as the modified Proctor test (ASTM Test Designation D-1557 and AASHTO Test
Designation T-180).
6. b) Differentiate between SPCT and MPCT
SPCT
• Mold Volume= 944 cm3(ft3)
• Mold Diameter= 101.6 mm (4in)
• Mold Height= 116.43mm (4.584in)
• Weight of Hammer= 2.5 Kg (6.5lb)
• Height of drop= 304.8mm(12in)
• Number of Soil Layer= 3
• Number of blows/layer= 25blows
• Compaction Energy= 594 KN-m/m3
MPCT
• Mold Volume= 944 cm3(ft3)
• Mold Diameter= 101.6 mm (4in)
• Mold Height= 116.43mm (4.584in)
• Weight of Hammer= 4.54 Kg (10lb)
• Height of drop= 457mm(18in)
• Number of Soil Layer= 5
• Number of blows/layer= 25blows
• Compaction Energy= 2700 KN-m/m3
8. Figure 4:-Comparison between standard Proctor hammer (left) and modified
Proctor hammer (right) (Courtesy of Braja M. Das, Henderson, Nevada)
9. c) Empirical relation for compaction test
For the both test,
• The moist unit weight of compaction γ, can be calculated as
γ= W/V(m)
Where, W= Weight of Compacted Soil in the mold.
V(m)= Volume of the mold (944cm3 or 1/30ft)
• The dry unit weight can be calculated as
γd=
γ ∗ 100
100+𝑊(%)
Where (w%)= Percent of moisture content
10. 4) Conclusion
• The modified Proctor test increases the compactive effort, resulting in
an increase in the maximum dry unit weight of the soil.
• A drop in the ideal moisture content coincides with an increase in the
maximum dry unit weight.
• The maximum dry unit weight and ideal moisture content are greatly
influenced by the distribution of grain sizes, the form of the soil
grains, the specific gravity of the soil solids, and the quantity and kind
of clay minerals present.
11. 5) References
DAS, B. M., “PRINCIPLES OF GEOTECHNICAL ENGINEERING 7th edition,”
Cengage Learning 2006 2010, P 144–155.
AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION
OFFICIALS (1982). AASHTO Materials, Part II, Washington, D.C.
AMERICAN SOCIETY FOR TESTING AND MATERIALS (2007). Annual Book
of ASTM Standards, Vol 04.08, West Conshohocken, Pa.
