pee lab 3 (specific gravity)

ABUBAKAR TAFAWA BALEWA UNIVERSITY,

PMB 0248, BAUCHI

SCHOOL OF ENGINEERING AND ENGINEERING TECHNOLOGY

PETROLEUM ENGINEERING PROGRAMME

PETROLEUM ENGINEERING LABORATORY REPORT

FIRST SEMESTER, 2011/2012 SESSION

EXPERIMENT 3: SPECIFIC GRAVITY OF SOIL PARTICLES

NAME: ISAAC CHUKWUDI VICTOR CHIMEZIE

REG. No.: 09/21700/U/2

LEVEL: 300

COURSE CODE: PEE 315

SUPERVISOR: SULEIMAN A. MOHAMMED

ABSTRACT

Specific gravity of the soil grains is an important property and is used to determine the voids

ratio, porosity, and degree of saturation if density and water content are known.

Density, as applied to any kind of homogeneous monophasic material of mass M and

volume V, is expressed as the ratio of M to V. Under specified conditions, this definition

leads to unique values that represent a well-defined property of the material. For

heterogeneous and multiphasic materials, however, such as porous media, application of

this definition can lead to different results, depending on the exact way the mass and

volume of the system are defined.

The soil particle density of a soil sample is calculated on the basis of the measurement of

two quantities: (1) Ms, the mass of the solid phase of the sample (dried mass) and (2) Vs, the

volume of the solid phase. Assuming that water is the only volatile in a soil sample, the mass

(Ms) can be obtained by drying the sample (usually at 110 ± 5C) until it reaches a constant

weight, Ws. This method may not be valid for organic soils or soils with asphalt.

The experiment conducted was carried out to determine the specific gravity of soil samples

using density bottle method.

The experiment was carried out hitch-free in the PEE Lab as all apparatus were adequately

provided and we were able to know the technical know-how on the determination of

specific gravity of soil sample.

Three (3) samples were provided i.e. Granite, Gypsum and Sandstone having Specific

Gravities of 2.5, 2.476 and 2.609 respectively. Thereafter the average was taken, which was

gotten to be 2.528.

It was therefore noted that Sandstone has the highest specific gravity followed by Granite

and Gypsum.

2 | S p e c i f i c G r a v i t y o f S o i l P a r t i c l e s 0 9 / 2 1 7 0 0 / U / 2

INTRODUCTION

At the end of this experiment, the student should have at least known the following:

1. Determination of Specific Gravity of various samples.

2. The knowledge on how to use the Density Bottle.

3. The use of specific gravity to carry out rock analysis on pore spaces.


LITERATURE REVIEW

Soil is a typical heterogeneous multiphasic porous system which, in its general form,

contains three natural phases: (1) the solid phase or the soil matrix (formed by mineral

particles and solid organic materials); (2) the liquid phase, which is often represented by

water and which could more properly be called the soil solution; and (3) the gaseous phase,

which contains air and other gases. In this three-phase soil system, the concept of average

density can be used to define the following densities: (1) density of solids or soil particle

density, s; (2) bulk or dry density, b; and (3) total or wet density.

The masses and volumes associated with the three soil phases must be defined before the

definitions of the different densities that characterize the soil system can be formalized.

Thus, consider a representative elementary volume (REV) of soil that satisfies the following

criteria:

1. A sufficiently large volume of soil containing a large number of pores, such that the

concept of mean global properties is applicable, and

2. A sufficiently small volume of soil so that the variation of any parameter of the soil from

one part of the domain to another can be approximated by continuous functions.

The soil particle density, or the density of solids, represents the density of the soil (i.e.,

mineral) particles collectively and is expressed as the ratio of the solid phase mass to the

volume of the solid phase of the soil.

Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a

substance to the density of a given reference material. Specific gravity usually means

relative density with respect to water. The term "relative density" is often preferred in

modern scientific usage.

If a substance's relative density is less than one then it is less dense than the reference; if

greater than 1 then it is denser than the reference. If the relative density is exactly 1 then

the densities are equal; that is, equal volumes of the two substances have the same mass. If

the reference material is water then a substance with a relative density (or specific gravity)

less than 1 will float in water. For example, an ice cube, with a relative density of about 0.91,

will float. A substance with a relative density greater than 1 will sink.


For the Specific Gravity of Soil Sample using Density Bottle is expressed as:

GS=w2−w1

(w¿¿ 4−w1)−(w¿¿3−w2)×Density of H 20¿¿

Where:

GS - Specific Gravity

W1 - Weight of Empty Density Bottle with Stopper

W2 - Weight of Soil Sample, Empty Density Bottle and Stopper

W3 - Weight of Empty Density Bottle, Soil Sample, Stopper and Distilled Water

W4 - Weight of Full Density Bottle, Soil Sample, Stopper and Water

In most mineral soils, the soil particle density has a short range of 2.6-2.7 g/cm3. This density

is close to that of quartz, which is usually the predominant constituent of sandy soils. A

typical value of 2.65 g/cm3 has been suggested to characterize the soil particle density of a

general mineral soil. Aluminosilicate clay minerals have particle density variations in the

same range. The presence of iron oxides and other heavy minerals increases the value of the

soil particle density. The presence of solid organic materials in the soil decreases the value.

Specific gravity values for a soil are not normally used strictly for classification purposes, but

are used in the calculation and interpretation of other test results. The specific gravity tests

specified in the British Standard (BS 1377:part 2:1990, clause 8) are relatively simple and are

based upon determination of the dry weight of a sample of the soil, and the weight of the

same sample plus water in a container of known volume. The volume of the container is

obtained by weighing the container empty, and full of water. The main problems in

conducting the test are of accurate weighing, and complete removal of the air from the soil

after the addition of water.

The method still used by most test houses to determine the particle density of fine-grained

soil utilizes a 50m1 density bottle (BS 1377:part 2:1990 clause 8.3). Unfortunately there is no

simple means of knowing when all the air has been removed from the bottle and hence the

soil must be de-aired under vacuum. The use of de-aired water will help but it is still

necessary to leave the sample in the density bottle under vacuum for several hours. The

major difficulty with this test is the provision of a satisfactory vacuum and measuring the

length of time required to remove the air completely. These factors can clearly lead to

errors in specific gravity determinations. Krawczyk (1969) found that the difficulties of de-

airing the soil could be overcome by shaking the sample instead of placing it under vacuum.


The advantages of shaking are that the shaking action is easily standardized and the removal

of air is more rapid than by the application of a vacuum. Krawczyk proposed that the test

should be carried out in a 1 litre gas jar to make the same test suitable for fine-, medium-

and coarse-grained soils and the shaking action provided by an end-over-end shaker. This

alternative method has been included in the British Standard (BS 1377:part 2:1990, clause

8.2) and should be treated as the preferred method, since in providing a more reliable

technique of de-airing the soil it yields more repeatable results.

The results of particle density tests are used in the interpretation of sedimentation test

results, to check the results of laboratory compaction tests (BS 1377:1975, clauses 4.1.4,

2.1), and to find the voids ratios of samples during consolidation tests. Incorrect particle

density values affect the position of the voids ratio vs. logarithm of pressure plot for an

oedometer consolidation test but they do not affect the values of the coefficients of

consolidation (Cv) or compressibility (Mv). A change in particle density leads to a different

particle size distribution from the sedimentation test, but the difference is not large and is

probably considerably less than the effects of natural soil variability or the assumptions

involved in the test.

The major problem arising from an incorrect particle density determination is that of the

credibility of compaction tests carried out on the same soil. A low particle density value will

push the zero air voids line on a dry density/moisture content plot down and to the left, and

may show compaction test results to be apparently impossible (and therefore inaccurate) as

they cross over the zero air voids line.

Its value helps to some extent in identification and classification of solids. It gives an idea

about the stability of soil as a construction material; higher value of specific gravity gives

more strength for roads and foundation. It is used in comparing the soil particle size by

means of hydrometer analysis. It is also used in estimation of critical hydraulic gradient in

soil when sand boiling condition is being studied and in zero air void calculation in the

compaction theory of solids.

Its value ranges as follows:

1. Coarse grained soils: 2.6 to 2.7

2. Fine grained soil: 2.7 to 2.8

3. Organic soil: 2.3 to 2.5


PROCEDURE

1. The density bottle was weight completely with a stopper after it was being dried

completely to obtain (W1).

2. 5g of soil passing the 2mm BS sieve was riffled from a large sample, oven dry sample at

105 – 110OC and was cooled in a desiccator and placed in the density – bottle. The soil,

bottle and stopper were weighed together to obtain W2.

3. Water was added to the bottle to cover the soil and was gently subjected to a vacuum

in the desiccator for one hour to avoid rigorous boiling until air was no more seen.

4. The bottle was vibrated and the process was then repeated until air was no longer

released.

5. Thereafter, more de-aired distilled water was added to fill the bottle.

6. The stopper was then fitted and the whole left at a constant temperature of 20OC for 1

hour.

7. The density bottle (empty), stopper, soil sand and distilled water was thereafter

weighed to get W3.

8. The bottle was thoroughly cleaned and filled with water. It was then allowed to stand

for 1 hour. There was no apparent decrease in water volume hence there was no need

for the bottle to be topped – up and allowed to stand for a further period of time.


INSTRUMENTATION

1. Density Bottle

2. Stopper

3. Water (Distilled)

4. Desiccator

5. Thermometer

6. Weighing Balance

SAMPLES USED

1. Granite

2. Gypsum

3. Sandstone


RESULTS AND DISCUSSION

SAMPLES USED

Granite (g) Gypsum (g) Sandstone (g)

Weight (g) Mass (g) 5.0 5.0 5.0

W1 – Empty Bottle + Stopper - 19.0 19.0 19.0

W2 – Sample + Empty Bottle + Stopper - 24.0 24.2 25.0

W3 – Sample + Water + Bottle + Stopper - 46.7 46.8 47.4

W4 – Sample + Water + Full Bottle + Stopper - 43.7 43.7 43.7

Specific Gravity 2.5 2.467 2.609

Average Specific Gravity 2.528 2.528 2.528

DISCUSSION

The experiment was conducted successfully without any problems as all necessary

help provided.

As earlier mentioned, the specific gravity of the samples was calculated and

Sandstone was observed to have the highest specific gravity of 2.609 followed by Granite,

which had a Specific Gravity of 2.5 and lastly Gypsum, having 2.467. The average specific

gravity was calculated to be 2.528.


RECOMMENDATION

The density bottle is the main apparatus, which was being used during the

experiment is used in determining the specific gravity or relative density of substances.

The experiment was carried out successfully in the PEE Laboratory without any

interference but I strongly recommend that de-aired distilled water be used instead of

ordinary water so as to prevent minor alterations in results.


CONCLUSION

The experiment was conducted successfully in the laboratory and hence the aim of

the experiment was achieved. It was discovered that the specific gravity of different soil

samples vary. From the ones provided: Granite, Gypsum and Sandstone, it was observed

that Gypsum had the lowest specific gravity followed by Granite while Sandstone had the

highest specific gravity holding a value of 2.609.

APPENDIX


Calculation for the Specific Gravity

GS=w2−w1

(w¿¿ 4−w1)−(w¿¿3−w2)×Density of H 20¿¿

GS - Specific Gravity

W1 - Weight of Empty Density Bottle with Stopper

W2 - Weight of Soil Sample, Empty Density Bottle and Stopper

W3 - Weight of Empty Density Bottle, Soil Sample, Stopper and Distilled Water

W4 - Weight of Full Density Bottle, Soil Sample, Stopper and Water

Density of Water = 1.0g/cm3

For Granite:

W1 = 19.0g W2 = 24.0g W3 = 46.7g W4 = 43.7g

GS= 24−19(43.7−19 )−(46.7−24)

GS=52

GS=2.5

For Gypsum:

W1 = 19.0g W2 = 24.2g W3 = 46.8g W4 = 43.7g

GS= 24.2−19(43.7−19 )−(46.8−24.2)

GS=5.22.1

GS=2.476

For Sandstone:

W1 = 19.0g W2 = 25.0g W3 = 47.4g W4 = 43.7g

GS= 25−19(43.7−19 )−(47.4−25)

GS= 62 .3

GS=2.609


BIBLIOGRAPHY

Engineer Manual (1970), Laboratory Soil Testing. Engineering and Design. EM 1110-2-1906

Fox R. W. McDonald, A. T. (2003), Introduction to Fluid Mechanics. 4th Edition. Wiley. USA

Jackie Chee (2007), Pet E 327 Lab Report #1, Alberta, Canada

UNESCO-NIGERIA Technical & Vocational Education, Hydrogeology Practical Manual

Laboratory Manual, Determination of Specific Gravity using Density Bottle Method

www.articlebase.com

www.civilengineering.com/papers/soil_sample/relative_density/wk12239820.htm

www.wikipedia.com/en/density_bottle.htm

www.wikipedia.com/en/relative_density.htm

www.wikipedia.com/en/soil_density.htm


http://www.wikipedia.com/en/soil_density.htm

http://www.wikipedia.com/en/relative_density.htm

http://www.wikipedia.com/en/density_bottle.htm

http://www.civilengineering.com/papers/soil_sample/relative_density/wk12239820.htm

http://www.articlebase.com/

pee lab 3 (specific gravity)

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