1 laboratory compaction test of soil (1)

GEOTECHNICAL ENGINEERING II (CECE4131)

Course Title: Geotechnical Engineering - 2Course Code: CECE 4131

Level: BaccalaureateCourse Lecturer : Mr. Jayram

Laboratory Technician: MrBoggarapuSrinivas

Experiment - 1Laboratory Compaction Test of Soil

Shinas College of Technology -Soil Mechanics Lab Semester II (2014-2015)

Student NameStudent ID No.Section No.Group No.Date of Performance

Shinas College of Technology

Department of Engineering

Civil Engineering Section


Laboratory Compaction Test of Soil

1.1 ObjectiveThis test will enable the student to determine the relationship between compacted dry density and soil

moisture content, and find out the maximum dry density and optimum moisture content of the soil

sample.

1.2 Need and ScopeSoil placed as engineering fill (embankments, foundation pads, road bases) must be compacted to the

selected density and moisture content to ensure the desired performance and engineering properties

such as shear strength, compressibility, or permeability. Also, foundation soils are often compacted to

improve their engineering properties. Laboratory compaction tests provide the basis for determining

the percentage compaction and moisture content needed in the field, and for controlling construction

to assure that the target values are achieved.

1.3 Standard ReferenceBS 1377 Part 4 Section 3 – Determination of dry density/moisture content relationship using 2.5kg

rammer

1.4 Required Materials and Equipment1.4.1 2.5 kg rammer

1.4.2 Soil compaction machine (optional)

1.4.3 Compaction mould, 1L

1.4.4 BS CBR Mould

1.4.5 BS Test Sieves 63mm, 37.5mm, 20mm

1.4.6 A scale (electronic balance), readable to 0.1g and 1g

1.4.7 Stainless containers

1.4.8 Medium size metal scoop


GEOTECHNICAL ENGINEERING II (CECE4131)1.4.9 Spatula

1.4.10 Watertight plastics, or polythene bags

1.4.11 Straightedge

1.4.12 Drying Oven 105°C to 110°C

1.4.13 Measuring Cylinder

1.4.14 Wash bottle

1.4.15 Rubber mallet or soil extruder

1.4.16 Mould oil (for slight greasing inside the mould)

Note: A compaction mould of 1L internal volume is used for soil in which all particles pass a 20mm

test sieve. If there is a limited amount of particles up to 37.5mm size, same tests are carried out in the

larger California Bearing Ratio (CBR mould).



1.5 Test Specimen1.5.1 Prepare and subdivide the initial sample by quartering or riffling to get the desired minimum

sample required based on the table below:

Minimum percentage

passing 20mm test sieve

Minimum mass of

prepared soil requiredType of mould used

100% 15kg 1L

70% 40kg CBR

Table 1: Minimum mass of soil required and corresponding mould to be used

1.5.2 Spread the soil sample on a large pan and let it air-dry for at least one day.

1.5.3 Subdivide the initial sample to produce 5 or more representative samples, each of about 2.5kg.


GEOTECHNICAL ENGINEERING II (CECE4131)1.5.4 Mix each sample thoroughly with a different amount of water to give a suitable range of

moisture contents. The range of moisture contents shall be such that at least 2 values lie either side of

the optimum at which the maximum dry density occurs. The procedures below show how to place

different amount of water in the sample.

1.5.4.1 Calculate how much amount of water to be placed in a 2.5kg mass of soil using 2% by mass.

1.5.4.2 Place the desired water and mix thoroughly with the sample. Visually check the mix sample by

squeezing it into your hand and gently release it. If the soil sticks together and forms a lump, this

means that it is near to optimum moisture content and can be set as sample 3. But if the soil looses

after releasing your hand, meaning you still need to add more calculated water and mix the sample

again, repeating the same procedure. Upon attaining the desired mixture (take note of the amount of

water placed), put the soil sample in an airtight plastic bag.

1.5.4.3 After preparing sample 3, get one of the representative samples and prepare it for sample 1 by

placing 2% in ml of 2.5kg of soil. Mix the sample and place it in an airtight plastic bag.

1.5.4.4 Another sample will be mixed with a calculated amount of water 2% or 4% more than the

amount of water placed in sample 1. Mix the sample and place it in an airtight plastic bag.

1.5.4.5 In preparing for sample 4, place 2% or 4% more water which you had placed in sample 3 in

another sample. Mix and place it in an airtight plastic bag.

1.5.4.6 Lastly, mix the remaining soil sample as sample 5 with 2% or 4% water which you had placed

in sample 4. Mix and place it in an airtight plastic bag.

Note: Leave all mixed samples for about one day.

1.6 Procedure1.6.1 Weigh the mould with base plate attached to 1g (m1).

1.6.2 Determine the inside volume of the mould by measuring the internal dimension to 0.1mm.

1.6.3 Attached the extension to the mould and place the mould assembly on a solid base.

1.6.4 Place a quantity of moist soil (sample 1) in the mould such that when compacted, it occupies a

little over one-third of the height of the mould body.

1.6.5 Apply 27 blows from the rammer by dropping it to the soil using the guide tube. Distribute the

blows uniformly starting from the sides to centre over the surface. Ensure that the rammer always falls

freely and not obstructed by soil in the guide tube.

1.6.6 Repeat 5.6.4 and 5.6.5. As for the last layer, the surface should not be 6mm more of the upper

edge of the mould body.


GEOTECHNICAL ENGINEERING II (CECE4131)1.6.7 Remove the extension, strike off the excess soil and level off the surface of the compacted soil

carefully to the top of the mould using the straightedge. Replace any coarse particles, removed in the

levelling process and press in well.

1.6.8 Weigh the soil and mould with baseplate to 1g (m2).

1.6.9 Remove the compacted soil from the mould using rubber mallet or soil extruder and place it in a

container. Take a representative sample of about 1kg for moisture content.

1.6.10 Repeat procedures 5.6.1 to 5.6.9 for the rest of the samples. Make sure to clean the mould and

grease it slightly before every use.

Note: Prepare 5 representative of initial sample, 6kg each in using CBR mould.

1.7 Calculations:1.7.1 Calculate for the moisture content of the soil samples.

1.7.2 Calculate the bulk density, ρ (Mg/m3), of each compacted specimen using the formula below.

m2 - m1

V

where:

m1 – is the mass of mould and baseplate, g

m2 – is the mass of mould, baseplate, and compacted soil, g

V – volume of mould with baseplate, cm3

1.7.3 Calculate the dry density ρd (Mg/m3), of each compacted specimen from the equation

100 ρ

100 + w

where:

ρ – is the bulk density, Mg/cm3

w – moisture content, %

1.7.4 Plot the dry densities obtained as Y-axis, and moisture content as X-axis. Draw a curve of best

fit to the plotted points and identify the position of the maximum on this curve. Read off the values of

dry density and moisture content to three significant figures corresponding to that point.


ρ =

ρd =

GEOTECHNICAL ENGINEERING II (CECE4131)WORKSHEET FOR DETERMINATION OF MAXIMUM DRY DENSITY (MDD) AND

OPTIMUM MOISTURE CONTENT (OMC) OF SOIL using 2.5KG RAMMER

Location Sample No.

Soil Description Date

Test no. 1 2 3 4 5

Mass of mould + baseplate, (m1) g

Mass of mould + baseplate + compacted specimen,

(m2) g

Mould volume, (V) cm3

Mass of compacted specimen, (m2- m1) g

Bulk Density, (ρ), (m2- m1/V) Mg/ m3

Container no.

Mass of container g

Mass of wet soil + container g

Mass of dry soil + container g

Mass of moisture g

Mass of dry soil g

Moisture content, (w) %

Dry Density, (ρd) (100 ρ)/(100+w) Mg/ m3


MDD (Mg/ m3)

OMC (%)


Moisture Content (%)

Worksheet No. 1: Laboratory Compaction Test using 2.5kg Rammer


Dry

Den

sity

(Mg/

m3 )

1 laboratory compaction test of soil (1)

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