Experiment No. 3
DETERMINATION OF WATER CONTENT, UNIT WEIGHT, VOID RATIO
AND DEGREE OF SATURATION OF SOIL
1. Objective(s):
To introduce to the student the procedure in determining the weight-volume characteristics of the soil.
2. Intended Learning Outcomes (ILOs):
The students shall be able to:
• connect the relationship of water content, unit weight, void ratio and degree of saturation.
• describe methods in determining water content, unit weight, void ratio and degree of saturation.
3. Discussion:
The determination of water content, unit weight and void ratio is an important requirement in laboratory tests
and is part of the test included in more elaborate tests. Water content is an important measure in the
compaction of soil. In order that correct water content is obtained from a soil sample, several samples at
different points must be taken. They are then mixed and the water content is then obtained from this soil
sample.
Various methodologies have been devised to determine the unit weight of the soil in the field such as
calibrated bucket method, nuclear method to name a few. For determination of the unit weight in a laboratory
setting, paraffin wax can be used in determining the unit weight. The paraffin coating applied on the soil will
allow determination of its volume as it is submerged in water.
The specific gravity of the solid grains of the soil is an engineering parameter which is dependent on the
mineralogy of the soil and the structure of its solid grains. Upon determination of the specific gravity, the
void ratio and degree of saturation of the soil can then be determined mathematically.
4. Resources:
1.
2.
3.
4.
5.
6.
Tin cup
Sensitive Balance
Oven
Pycnometer
Bunsen burner
Paraffin wax
5. Procedure:
Note: For this experiment, coarse-grained soil sample is to be utilized to expedite the oven-drying of the
sample.
Water Content Determination
1. Weigh a tin cup including its cover; identify the cover and its lid. Determine the weight of the tin cup.
2. Place a representative sample of wet soil in the cup. Determine the weight of wet soul and tin cup.
10
3. Place the sample in the oven for at least 3 hours.
4. When the sample has dried to constant weight, obtain the weight of cup and dry soil
5. Compute the water content. The difference between weight of wet soil plus cup and weight of dry
soil plus cup is the weight of water (Ww). Also compute the weight of dry soil (Ws).
6. To determine the water content ().
 = Ww/Ws x 100
7. Repeat until three (3) trials are achieved. Determine the average moisture content.
Unit Weight Determination
1. Trim a sample of soil to about 1 ½ inches diameter and 2 to 3 inches long. Surface should be smooth
and rounded. Weigh to up to the nearest 0.1 gram.
2. Cover with a thin coating of paraffin and weigh again. Compute the volume of paraffin from weight
of paraffin. The specific gravity of paraffin is about 0.9
3. Immerse the coated sample in water in the graduated cylinder and determine its displacement. The
volume of the sample is the volume of the water displaced minus the volume of the paraffin.
4. Compute the unit weight in grams/cu. cm.
Calculations:
• The volume of the paraffin is equal to the weight of paraffin used to coat sample divided by the
density of paraffin. Density of paraffin is 0.90
Wt. of paraffin = Wt. Soil coated with paraffin – wt. of soil uncoated with paraffin
•
The volume of the paraffin—coated sample is equal to the weight in air minus the weight in water,
(express the weight in gm)
•
Wet density of soil =
wt of soil
vol of soil
g/cc or kg/m
Specific Gravity Determination:
Calibration of Pycnometer
1. Transfer carefully the 25 gm sample to the calibrated bottle and add distilled water until about ½
full. Care must be exercised so as not to lose any of the soil in the transfer.
2. Expel the entrapped air by boiling gently for at least 10 minutes. Roll the bottle occasionally to
facilitate the removal of air.
3. Cool the sample to room temperature or to a temperature within the range of the calibration curve
of the bottle used.
Determination of Specific Gravity
1. Fill the bottle with distilled water to the calibration mark as discussed in step 2 from calibration of
bottle.
2. Dry the outside of the bottle, as in step 3, pycnometer calibration.
3. Weigh the bottle with water and soil, and record as Wb.
11
4. Read and record the temperature of the contents to 0.1 °C, as in step 5, pycnometer calibration.
5. Repeat procedure for at least 3 trials.
Note:
An alternative heating device that can be used is an electric plate stove with wire gauze.
Gs =
Gt (Ws)
Ws + Wa – Wb
Where:
Gs – Specific gravity
Gt – Specific gravity of distilled water at the temperature when
Wb was obtained (refer to Table A)
Ws – Weight of oven-dried sample
Wa – weight of bottle + water (from calibration curve)
Wb – weight of bottle + soil and water
Determination of Void Ratio and Degree of Saturation:
The void ratio can be determined from the formula shown below:
e=
wGs (1+w) 
1
The degree of saturation can be determined from the formula shown below:
S = Gs/e
12
Course:
Group No.:
Group Leader:
Group Members:
1.
2.
3.
4.
5
6. Data and Results:
Experiment No.:
Section:
Date Performed:
Date Submitted:
Instructor:
Moisture Content Determination
Description
Sample 1
Sample 2
Wt of tin cup (Wc)
Wt. of tin cup + Wet Soil (Wc+ws)
Wt. of tin cup and dry soil (Wc+dc)
Wt. of water (Ww)
Wt. of dry soil (Wds)
Water Content ()
Average
Description
Wt. of soil (Ws)
Wt. of soil and paraffin
(Ws+p)
Volume of soil+paraffin
(Vs+p)
Sample 3
Unit Weight Determination
Description
Wt. of paraffin (Wp)
Volume of paraffin (Vp)
Volume of soil (Vs)
Unit weight ()
Description
SG of distilled water (Gt)
Wt. of oven-dried
sample (Ws)
Specific Gravity Determination
Description
Wt. of bottle + water (Wa)
Weight of bottle + soil +
water (Wb)
Specific gravity of soil (Gs)
Determination of Void Ratio and Degree of Saturation
Void ratio
Degree of Saturation
13
7. Conclusion:
8. Assessment (Rubric for Laboratory Performance):
BEGINNER
1
CRITERIA
ACCEPTABLE
2
PROFICIENT
3
SCORE
I. Laboratory Skills
Manipulative
Skills
Experimental
Set-up
Process Skills
Safety
Precautions
Members
occasionally
demonstrate needed
skills
Members are unable Members are able to
to set-up the
set-up the materials
materials.
with supervision.
Members
Members do not
occasionally
demonstrate targeted
demonstrate targeted
process skills.
process skills.
Members do not
Members follow
follow safety
safety precautions
precautions.
most of the time.
Members do not
demonstrate needed
skills.
II. Work Habits
Time
Members do not
Management /
finish on time with
Conduct of
incomplete data.
Experiment
Members finish on
time with incomplete
data.
Members always
demonstrate needed
skills.
Members are able to setup the material with
minimum supervision.
Members always
demonstrate targeted
process skills.
Members follow safety
precautions at all times.
Members finish ahead of
time with complete data
and time to revise data.
14
Cooperative
and Teamwork
Members do not
know their tasks and
have no defined
responsibilities.
Group conflicts have
to be settled by the
teacher.
Neatness and
Orderliness
Messy workplace
during and after the
experiment.
Ability to do
independent
work
Members require
supervision by the
teacher.
Other Comments/Observations:
Members have
defined
responsibilities most
of the time. Group
conflicts are
cooperatively
managed most of the
time.
Clean and orderly
workplace with
occasional mess
during and after the
experiment.
Members require
occasional
supervision by the
teacher.
Members are on tasks
and have defined
responsibilities at all
times. Group conflicts are
cooperatively managed at
all times.
Clean and orderly
workplace at all times
during and after the
experiment.
Members do not need to
be supervised by the
teacher.
Total Score
(𝑇𝑜𝑡𝑎𝑙 𝑆𝑐𝑜𝑟𝑒)
𝑅𝑎𝑡𝑖𝑛𝑔 =
24
× 100
9. Documentation
15