This Test Is Done to Determine the Maximum Dry Density and the Optimum Moisture Content

This test is done to determine the maximum dry density and the optimum moisture content of soil using heavy compaction as per IS: 2720 (Part 8 ) – 1983.The apparatus used is

i) Cylindrical metal mould – it should be either of 100mm dia. and 1000cc volume or 150mm dia. and 2250cc volume and should conform to IS: 10074 – 1982.
ii) Balances – one of 10kg capacity, sensitive to 1g and the other of 200g capacity, sensitive to 0.01g
iii) Oven – thermostatically controlled with an interior of noncorroding material to maintain temperature between 105 and 110oC
iv) Steel straightedge – 30cm long
v) IS Sieves of sizes – 4.75mm, 19mm and 37.5mm

PREPARATION OF SAMPLE
A representative portion of air-dried soil material, large enough to provide about 6kg of material passing through a 19mm IS Sieve (for soils not susceptible to crushing during compaction) or about 15kg of material passing through a 19mm IS Sieve (for soils susceptible to crushing during compaction), should be taken. This portion should be sieved through a 19mm IS Sieve and the coarse fraction rejected after its proportion of the total sample has been recorded. Aggregations of particles should be broken down so that if the sample was sieved through a 4.75mm IS Sieve, only separated individual particles would be retained.
Procedure To Determine The Maximum Dry Density And The Optimum Moisture Content Of Soil
A) Soil not susceptible to crushing during compaction –
i) A 5kg sample of air-dried soil passing through the 19mm IS Sieve should be taken. The sample should be mixed thoroughly with a suitable amount of water depending on the soil type (for sandy and gravelly soil – 3 to 5% and for cohesive soil – 12 to 16% below the plastic limit). The soil sample should be stored in a sealed container for a minimum period of 16hrs.

ii) The mould of 1000cc capacity with base plate attached, should be weighed to the nearest 1g (W1). The mould should be placed on a solid base, such as a concrete floor or plinth and the moist soil should be compacted into the mould, with the extension attached, in five layers of approximately equal mass, each layer being given 25 blows from the 4.9kg rammer dropped from a height of 450mm above the soil. The blows should be distributed uniformly over the surface of each layer. The amount of soil used should be sufficient to fill the mould, leaving not more than about 6mm to be struck off when the extension is removed. The extension should be removed and the compacted soil should be levelled off carefully to the top of the mould by means of the straight edge. The mould and soil should then be weighed to the nearest gram (W2).

iii) The compacted soil specimen should be removed from the mould and placed onto the mixing tray. The water content (w) of a representative sample of the specimen should be determined.

iv) The remaining soil specimen should be broken up, rubbed through 19mm IS Sieve and then mixed with the remaining original sample. Suitable increments of water should be added successively and mixed into the sample, and the above operations i.e. ii) to iv) should be repeated for each increment of water added. The total number of determinations made should be at least five and the moisture contents should be such that the optimum moisture content at which the maximum dry density occurs,
lies within that range.

B) Soil susceptible to crushing during compaction –
Five or more 2.5kg samples of air-dried soil passing through the 19mm IS Sieve, should be taken. The samples should each be mixed thoroughly with different amounts of water and stored in a sealed container as mentioned in Part A)

C) Compaction in large size mould –
For compacting soil containing coarse material upto 37.5mm size, the 2250cc mould should be used. A sample weighing about 30kg and passing through the 37.5mm IS Sieve is used for the test. Soil is compacted in five layers, each layer being given 55 blows of the 4.9kg rammer. The rest of the procedure is same as above.
REPORTING OF RESULTS
Bulk density Y(gamma) in g/cc of each compacted specimen should be
calculated from the equation,
Y(gamma) = (W2-W1)/ V
where, V = volume in cc of the mould.

The dry density Yd in g/cc
Yd = 100Y/(100+w)

The dry densities, Yd obtained in a series of determinations should be plotted against the corresponding moisture contents,w. A smooth curve should be drawn through the resulting points and the position of the maximum on the curve should be determined. A sample graph is shown below:

The dry density in g/cc corresponding to the maximum point on the moisture content/dry density curve should be reported as the maximum dry density to the nearest 0.01. The percentage moisture content corresponding to the maximum dry density on the moisture content/dry density curve should be reported as the optimum moisture content and quoted to the nearest 0.2 for values below 5 percent, to the nearest 0.5 for values from 5 to 10 percent and to the nearest whole number for values exceeding 10 percent.

DENSITY OF SOIL BY CORE CUTTER METHOD

Aim of the Experiment:

To determine the field or in-situ density or unit weight of soil by core cutter method

Apparatus Required:

a) Special:

i. Cylindrical core cutter

ii. Steel rammer

iii. Steel dolly

b) General:

i. Balance of capacity5 Kg and sensitivity 1 gm.

ii. Balance of capacity 200gms and sensitivity 0.01 gms.

iii. Scale

iv. Spade or pickaxe or crowbar

v. Trimming Knife

vi. Oven

vii. Water content containers

viii. Desiccator.

Theory:

Field density is defined as weight of unit volume of soil present in site. That is

Where, Density of soil

W = Total weight of soil

V = Total volume of soil

The soil weight consists of three phase system that is solids, water and air. The

voids may be filled up with both water and air, or only with air, or only with water.

Consequently the soil may be dry, saturated or partially saturated. In soils, mass of air is considered to be negligible, and therefore the saturated

density is maximum, dry density is minimum and wet density is in between the two.

Dry density of the soil is calculated by using equation,

Where, dry density of soil

Wet density of soil

w = moisture content of soil.

Density or unit weight of soils may be determined by using the following method:

i. Core cutter method

ii. Sand replacement test

iii. Rubber balloon test

iv. Water displacement method

v. Gamma ray method

Hear we use core cutter method, the equipment arrangement is shown as fallows, Application:

Field density is used in calculating the stress in the soil due to its overburden

pressure it is needed in estimating the bearing capacity of soil foundation system,

settlement of footing earth pressures behind the retaining walls and embankments.

Stability of natural slopes, dams, embankments and cuts is checked with the help of

density of those soils. It is the density that controls the field compaction of soils.

Permeability of soils depends upon its density. Relative density of cohesionless soils

is determined by knowing the dry density of soil in natural, loosest and densest

states. Void ratio, porosity and degree of saturation need the help of density of soil.

Core cutter method in particular, is suitable for soft to medium cohesive soils, in

which the cutter can be driven. It is not possible to drive the cutter into hard, boulder

or murrumy soils. In such case other methods are adopted.

Procedure:

i. Measure the height and internal diameter of the core cutter.

ii. Weight the clean core cutter.

iii. Clean and level the ground where the density is to be determined.

iv. Press the cylindrical cutter into the soil to its full depth with the help of steel

rammer.

v. Remove the soil around the cutter by spade.

vi. Lift up the cutter.

vii. Trim the top and bottom surfaces of the sample carefully.

viii. Clean the outside surface of the cutter.

ix. Weight the core cutter with the soil.

x. Remove the soil core from the cutter and take the representative sample in

the water content containers to determine the moisture content Precautions:

i. Steel dolly should be placed on the top of the cutter before ramming it down

into the ground.

ii. Core cutter should not be used for gravels, boulders or any hard ground.

iii. Before removing the cutter, soil should be removed around the cutter to

minimize the disturbances.

iv. While lifting the cutter, no soil should drop down

Observation and Calculation Table:

Internal diameter of cutter (cm): ______

Height of the cutter (cm): ______

Cross sectional area of the cutter (cm2): ______

Volume of the cutter, V (cm3): ______

Water/Moisture content determination:

sample 1 sample 2 sample 3

Weight of can, W1 (g)

Weight of can + wet soil W2 (g)

Weight of can + dry soil W3 (g)

Water/Moisture content Calculation Table:

sample 1 sample 2 sample 3

Mass of core cutter, W1 (gm)

Mass of cutter + soil from field, W2

(gm)

Wet density, (gm/cm3)

Dry density , (gm/cm3)

QUESTIONNAIRE:

i. Out of wet density, dry density, and saturated density, which one of them is

maximum and minimum? Explain.

ii. What are the main factors which affect in-situ density of soil? Explain.

iii. Beside the density what other properties do you need to calculate the void

ratio and degree of saturation of soils?

iv. What are the other methods to calculate the field density of soil?

Determine The In-Situ Dry Density Of Soil By Core Cutter Method

Posted inCivil Engineering Tests|Email This Post

This test is done to determine the in-situ dry density of soil by core cutter method as per IS: 2720 (Part XXIX) – 1975.The apparatus needed for this test is

i) Cylindrical core cutter
ii) Steel dolley
iii) Steel rammer
iv) Balance, with an accuracy of 1g
v) Straightedge
vi) Square metal tray – 300mm x 300mm x 40mm
vii) Trowel

Procedure Determine The In-Situ Dry Density Of Soil By Core Cutter Method
i) The internal volume (V) of the core cutter in cc should be calculated from its dimensions which should be measured to the nearest 0.25mm.

ii) The core cutter should be weighed to the nearest gram (W1).

iii) A small area, approximately 30cm square of the soil layer to be tested should be exposed and levelled. The steel dolly should be placed on top of the cutter and the latter should be rammed down vertically into the soil layer until only about 15mm of the dolly protrudes above the surface, care being taken not to rock the cutter. The cutter should then be dug out of the surrounding soil, care being taken to allow some soil to project from the lower end of the cutter. The ends of the soil core should then be trimmed flat in level with the ends of the cutter by means of the straightedge.

iv) The cutter containing the soil core should be weighed to the nearest gram (W2).

v) The soil core should be removed from the cutter and a representative sample should be placed in an air-tight container and its water content (w)

REPORTING OF RESULTS
Bulk density of the soil g ccY = [W2- W1]/ Vg/cc
Dry density of the soil g ccYd = 100Y/[100+w]g/cc

Average of at least three determinations should be reported to the second place of decimal in g/cc.
A sample proforma for the record of the test results is given below

TO DETERMINE DRY DENSITY OF SOIL BY CORE CUTTER METHOD

Theory:

A cylindrical core cutter is a seamless steel tube. For determination of the dry density of the soil, the cutter is pressed into the soil mass so that it is filled with the soil. The cutter filled with the soil is lifted up. The mass of the soil in the cutter is determined. The dry density is obtained as

Where M= mass of the wet soil in the cutter

V= internal volume of the cutter

w= water content.

Equipment:

1. Cylindrical core cutter, 100mm internal diameter and 130mm long

2. Steel rammer, mass 9kg, overall length with the foot and staff about 900mm.

3. Steel dolley, 25mm high and 100mm internal diameter

4. Weighing balance, accuracy 1g.

5. Palette knife

6. Straight edge, steel rule etc

Procedure

1. Determine the internal diameter and height of the core cutter to the nearest 0.25mm

2. Determine the mass (M1) of the cutter to the nearest gram.

3. Expose a small area of the soil to be tested. Level the surface, about 300mm square in area.

4. Place the dolley over the top of the core cutter and press the core cutter into the soil mass using the rammer. Stop the pressing when about 15mm of the dolley protrudes above the soil surface.

5. Remove the soil surrounding the core cutter, and take out the core cutter. Soil soil would project from the lower end of the cutter.

6. Remove the dolley. Trim the tip and bottom surface of the core cutter carefully using a straight edge.

7. Weigh the core cutter filled with the soil to the nearest gram (M2).

8. Remove the core of the soil from the cutter. Take a representative sample for the water content determination.

9. Determine the water content.

Observation and calculations:

Sl. No. / Observations an Calculations / Determination No.
1 / 2 / 3
Observation
1 / Core cutter No.
2 / Internal diameter
3 / Internal height
4 / Mass of empty core cutter (M1)
5 / Mass of core cutter with soils (M2)
Calculations
6 / M=M2– M1
7 / Volume of cutter V
8 / Water content
9 / Dry density using formula

Result:

Dry density of the soil= ______g/ml.

DENSITY TESTING AND

INSPECTION MANUAL

2003 EDITION

VERSION 1.0

April 8, 2010

CONSTRUCTION AND TECHNOLOGY

DIVISION Density Testing and Inspection Manual April 8, 2010