Compaction of soil

1. COMPACTION TEST
Prepared by:-
Saurav Poudel(11/077)
Central Department of
Geology
Tribhuvan University
Engineering Geology

2. INTRODUCTION
• Compaction is the process by which soil particles are packed
more closely together by dynamic loading such as rolling,
tamping or vibration it is achieved through the reduction of air
voids with little or no change in water content of soil.

3. PURPOSE OF COMPACTION TEST
• The purpose of a laboratory compaction test is to establish a
relationship between dry density and moisture content for a soil
under controlled conditions. R.R. Proctor (1933) was the first to
develop a method of assessing compacted fill that has since
become a universal standard and the test is known as standard
proctor test(SPCT).
• AASHO developed a modified test to give a higher standard of
compaction and is known as modified proctor test(MPCT).

4. STANDARD PROCTOR COMPACTION
TEST
Figure 1:-Standard Proctor test equipment: (a) mold; (b)
hammer
Standard Proctor Test is used to
determine the compaction of different
types of soil and the properties of soil
with a change in moisture content.
The practical maximum density of a
soil sample along with the optimum
moisture content needed to achieve
that density.

5. MODIFIED PROCTOR COMPACTION
TEST
Figure 2: Modified Proctor compaction test
Modified Proctor Test is performed to
know the characteristics of soil through
compaction with change in water content
ultimately giving us the relation between
dry density and moisture content.
It is a modified version of the Standard
Proctor Test.

6. DIFFERENTIATE BETWEEN SPCT
AND MPCT
• 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
• SPCT • MPCT
• Mold Diameter= 101.6 mm (4in)
• Mold Volume= 944 cm3(ft3)
• 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

7. 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

8. CONCLUSION
• Compaction improves the engineering properties like shear
strength, density, permeability etc.
• Increasing the bearing capacity of foundations.
• Decreasing the undesirable settlement of structures.
• Reduces the chances of slope stability problems like landslides.
• Reduces the amount of water that can be held in the soil by
decreasing the void ratio and thus helps in maintaining the
required strength.

9. THANK YOU