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CVEN365 Introduction to Geotechnical EngineeringLABORATORY MANUAL
Giovanna Biscontin
Texas A&M University
August 27, 2012
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Contents
1 Laboratory Safety and Policy 1
2 Determining Water Content of Soil Specimens 3
2.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 Water Content by Microwave Oven Method . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2.1 Standard Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2.2 Required Materials and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . 32.2.3 Test Specimen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2.4 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2.5 Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3 Water Content by Oven Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3.1 Standard Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3.2 Required Materials and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3.3 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3.4 Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3 Particle Size Analysis of Soils 9
3.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2 Standard Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.3 Particle size analysis of coarse grained fraction . . . . . . . . . . . . . . . . . . . . . . . . 9
3.3.1 Required Materials and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.3.2 Test Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.3.3 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3.4 Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.4 Particle size analysis of fine grained fraction . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.4.1 Required Materials and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.4.2 Hydrometer Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.4.3 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.4.4 Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.5 Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4 Atterberg Limits: Liquid Limit, Plastic Limit, and Plasticity Index of Soils 19
4.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2 Standard Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.3 Determination of Liquid Limit (Multi-Point Method) . . . . . . . . . . . . . . . . . . . . . 19
4.3.1 Required Materials and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.3.2 Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.3.3 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
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4.3.4 Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.4 Determination of Plastic Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.4.1 Required Materials and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.4.2 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.5 Plasticity Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5 Liquid Limit of Soils using the Drop Cone Penetrometer 25
5.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.2 Standard Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.3 Determination of Liquid Limit Using Drop Cone Penetrometer . . . . . . . . . . . . . . . . 25
5.3.1 Required Materials and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.3.2 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.3.3 Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6 Classification According to USCS 29
6.1 Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6.2 Initial Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6.2.1 Highly Organic Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296.2.2 Non Highly Organic Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.3 Procedure for Classification of Fine Grained Soils . . . . . . . . . . . . . . . . . . . . . . 30
6.4 Procedure for Classification of Coarse Grained Soils . . . . . . . . . . . . . . . . . . . . . 31
7 Visual Classification of Soils 33
7.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7.2 Standard Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7.3 Terminology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7.4 Descriptive Information for Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
7.5 Procedure for Identifying Fine-Grained Soils . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.6 Identification of Inorganic Fine-Grained Soils . . . . . . . . . . . . . . . . . . . . . . . . . 367.7 Procedure for identifying Coarse-Grained Soils . . . . . . . . . . . . . . . . . . . . . . . . 37
7.8 Check List For Description Of Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
8 Compaction Using Standard Effort 41
8.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
8.2 Standard Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
8.3 Required Materials and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
8.4 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
8.4.1 Specimen preparation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
8.4.2 Compaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
8.5 Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
9 Measuring Suction with the Filter Paper Method 47
9.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
9.2 Soil Suction Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
9.3 Required Materials and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
9.4 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
9.5 Soil Matric Suction Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
9.6 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
9.7 Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
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15 One-Dimensional Consolidation 87
15.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
15.2 Standard Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
15.2.1 Required Materials and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . 88
15.3 Preliminary Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
15.3.1 The consolidometer and the dial gauge . . . . . . . . . . . . . . . . . . . . . . . . 8915.3.2 The data acquisition software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
15.3.3 The remaining preliminary details . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
15.4 Specimen Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
15.5 Procedure for pneumatic load frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
15.6 Procedure for mechanical load frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
15.7 Second and following days . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
15.8 Last day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
15.9 Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
15.10Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
16 Triaxial Unconfined Compression Test 101
16.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10116.2 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
16.2.1 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
16.2.2 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
16.3 Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
16.4 Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
17 Unconsolidated Undrained Triaxial Test 105
17.1 Specimen preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
17.1.1 Preparation of the specimen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
17.1.2 Fitting end caps and membrane . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
17.2 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10617.3 Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
17.4 Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
18 Triaxial Consolidated Drained Compression Test 109
18.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
18.2 Summary of Test Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
18.2.1 Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
18.2.2 Specimen Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
18.2.3 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
18.3 Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
18.4 Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
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Chapter 1
Laboratory Safety and Policy
Safety is a priority at Texas A&M University!
While it may seem unlikely that an accident could happen to you, you should know the accident rate in
universities is 10 to 100 times greater than in the chemical industry. To help prevent accidents, safety notes
are included in the laboratory manual. In addition, relevant Material Safety Data Sheets (MSDS) are in a
laboratory binder and guidelines are posted. Pay close attention to this information - our goals are to avoid
accidents in the laboratory, and to respond promptly and appropriately should an accident occur.
Safety depends on you!
It is your responsibility to follow the instructions in the lab manual and any additional guidelines provided
by your instructor. It is also your responsibility to be familiar with the location and operation of safety
equipment such as eyewash units, showers, fire extinguishers, chemical spill cleanup kits etc. Questions
about chemicals can be answered by referring to the appropriate Material Safety Data Sheet. If you need
help deciphering an MSDS, please see your instructor.
Safety is a primary concern in all of the Zachry Department of Civil Engineering Geotechnical Engineer-
ing laboratories. Both the Undergraduate laboratory (CVLB 117) and Graduate laboratory (CVLB 116D) are
outfitted with equipment that could cause injury if one is not alert while performing experiments. Following
is an outline of general policy and Dos and Donts in these laboratories. Safety is everyones concern.
1. No food or drink is allowed in the laboratories.
2. Wear appropriate protective clothing. You will not be allowed in the lab if you are wearing open-
toe shoes and/or shorts. Avoid shirts with dangling sleeves. Tie back long hair and avoid dangling
jewelry.
3. No phone calls and no text messaging in the laboratory. Set your cell phones to silent mode.
4. Ovens:
The large ovens in both rooms are set at 105 degrees C. Use properly insulated gloves to handleobjects you are retrieving out of the oven. The gloves are placed near the oven for this purpose.
Please return the gloves to the table by the oven.
The microwave ovens are used for moisture determination in SOILS ONLY. Never place morethan ONE soil sample at a time (in its aluminum dish) in a microwave oven during this process.
Check that a heat sink (in the form of a ceramic bowl) is in the microwave to avoid explosions.
5. There are two fire extinguishers in the Undergraduate laboratory and one extinguisher in the Graduate
laboratory. Please observe the mounting locations on the walls and make a mental note of their access.
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6. Safety glasses are in a large white cabinet on the north wall of the Undergraduate Laboratory. Should
you need to use a hammer or blunt instrument to break up dried soil samples, then all members of the
laboratory group will be required to wear safety glasses during this process, including the teaching
assistant.
7. Each laboratory island has a sink with two faucets. One faucet provides hot and cold tap water and is
used for cleanup only. The other faucet has a white button on it and is labeled DW (distilled water).
8. During some sessions noise from machinery (such as sieve shakers) may get loud. If this becomes
a problem, please notify the teaching assistant and ear protection will be provided on an as-needed
individual basis.
9. Barrels are provided for used soil when the experiment is completed. Never throw trash (foil cups,
paper, plastic, etc.) in these barrels. There are trash bins provided for garbage.
10. At the end of each laboratory session always clean all the instruments and other materials used. A
paper towel dispenser hangs on the wall for cleanup.
11. Counterbalanced Load Frames:
There are four double load frames in the Undergraduate laboratory and two double load framesin the Graduate laboratory. These frames are safe to operate when using the correct procedure.
Never touch these frames when not in use.
When using the loading frames:
Never have your head under the top counterweight. The weight may fall while making
adjustments to the set up. This typically occurs at least once a semester. You want to make
sure the weight does not fall on you, and especially your head.
You are required to complete and sign (accept) aStudent Safety Contract Agreement(LSA) on Howdy
before the first laboratory class in order to be allowed to participate in the laboratory activities. Inaddition, you will have to pass a quiz on safety procedures in the geotechnical laboratories based on
the information in this chapter. Questions about safety will also be included in quizzes administered
at teh beginning of other laboratory sessions during the semester.
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Chapter 2
Determining Water Content of Soil
Specimens
2.1 Purpose
The water (or moisture) content of a soil is recorded in every test in geotechnical engineering. This basic
type of information provides insight on the conditions of the soil. The water content of undisturbed samples
from the site is also measured and reported on boring logs and in the engineering reports. Sometimes, we
need to mix a soil to a certain water content to meet specifications for construction.
Traditionally, we used a standard oven set at a temperature of 110oC. These days we can also use a
microwave oven, which gives immediate results. The two methods are only slightly different and they are
both explained in this chapter. You will mostly use the microwave oven method, but in a few cases the
standard method is more reliable. The instructions for the specific test will tell you which method to use for
each laboratory experiment.
2.2 Water Content by Microwave Oven Method
This method is commonly used as a quicker alternative to the standard oven drying method, therefore it is
mostly used when immediate results are needed. You cannot use the microwave oven method for soils with
significant levels of organics.
The main problem with using the microwave oven for water content determination is the possibility
of heating the soil to temperatures higher than 110o C. The higher temperature may actually change the
chemical structure of the clay minerals (think about pottery) and give wrong results. By drying the soil in
several steps you minimize the chance of overheating.
2.2.1 Standard Reference
ASTM D 4643- Standard test method for determination of water (moisture) content of soil by the microwave
oven heating.
2.2.2 Required Materials and Equipment
The following items will be required for this testing method:
A microwave oven. Variable power controls are important and reduce the potential for overheating thetest specimen.
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2. Determining Water Content of Soil Specimens 5
2.2.5 Calculations
Calculate the Water content of the sample as follows:
w=Mcws Mcs
Mcs Mc 100 =
MwMs
100 (2.1)
where:
w = water content, %
Mcws = mass of container and wet specimen, g
Mcs= mass of container and oven dry specimen, g
Mc= mass of container, g
Mw = mass of water, g and
Ms= mass of solid particles.
Moisture Content Determination by Microwave Oven
Sample No. B-24 Project
Boring No. 12-L Location
Depth 2.4 m
Description of sample Brown silty clay
Date 09/05/03 Tested by Jane Doe
Mass of container,Mc (g) 20.0After 3
min.
After 1
more
min.
After 1
more
min.
After 1
more
min.
After 1
more
min.
Initial mass of container + wet specimen,Mcws (g) 155.0 155.0 155.0 155.0 155.0
Mass of container + dry specimen,Mcs(g) 131.8 122.3 121.5 121.3 121.2
Mass of water,Mw=Mcws Mcs (g) 23.2 32.7 33.5 33.7 33.8
Mass of solid particles,Ms= Mcs Mc(g) 111.8 102.3 101.5 101.3 101.2
Moisture contentw = MwMs
100%(%) 20.75 31.96 33.00 33.27 33.39
Percent difference in water content (%) 11.21 1.04 0.27 0.12
Figure 2.1: Example of water content by microwave oven calculation
2.3 Water Content by Oven Method
Drying takes at least 12 hours in a standard oven, but the temperature is constant avoiding problems with
overheating. If you have a large sample, overheating is likely in a microwave oven, therefore the standard
oven is recommended.
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2.3.1 Standard Reference
ASTM D 2216- Standard test method for laboratory determination of water (moisture) content of soil and
rock by mass.
2.3.2 Required Materials and Equipment
The following items will be required for this testing method:
A drying oven at a temperature of 110oC 5oC.
A scale with readability of 0.01 g is required for specimens with mass of less than 200 g.
Specimen container suitable for use in an oven. For small samples (less than 200 g) use the aluminumcontainers with a lid to prevent moisture loss before drying and moisture gain from the air after drying.
The containers must be dry.
Gloves or holders to handle the container.
Tools such as knives, or spatulas.
A marker, if the container does not have an identifying feature.
2.3.3 Procedure
1. Make sure you have a copy of the appropriate moisture content determination form ready for use.
2. Determine the mass of a clean, dry container or dish, and record it. Remember to record the container
ID or mark the container. Many similar containers are placed in the oven at the same time and may be
moved. You want to make sure you will be able to find your specimen.
3. Place the soil specimen in the container, and immediately determine and record the total mass.
4. Place contained and soil specimen in the oven for at least 12 hours. Longer drying times will not
compromise the results.
5. After the set time has elapsed, remove the container and soil from the oven taking care not to burn
yourself, and immediately record the mass.
6. Calculate the water content.
2.3.4 Calculations
Follow the same procedure as above in section2.2.5.
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2. Determining Water Content of Soil Specimens 7
Moisture Content Determination by Microwave Oven
Sample No. Project
Boring No. Location
Depth
Description of sample
Date Tested by
Mass of container,Mc (g)After 3
min.
After 1
more
min.
After 1
more
min.
After 1
more
min.
After 1
more
min.Initial mass of container + wet specimen,Mcws (g)
Mass of container + dry specimen,Mcs(g)
Mass of water,Mw=Mcws Mcs (g)
Mass of solid particles,Ms= Mcs Mc(g)
Moisture contentw = MwMs
100%(%)
Percent difference in water content (%)
Moisture Content Determination by Oven
Sample No. Project
Boring No. Location
Depth
Description of sample
Date Tested by
Mass of container,Mc (g)
Initial mass of container + wet specimen,Mcws (g)
Mass of container + dry specimen,Mcs(g)
Mass of water,Mw=Mcws Mcs (g)
Mass of solid particles,Ms= Mcs Mc(g)
Moisture contentw = MwMs
100%(%)
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Nominal diameter of Approximate Minimum
largest particles Mass of Portion
in. (mm) g
3/8 (9.5) 500
3/4 (19.0) 1000
1 (25.4) 20001.5 (38.1) 3000
2 (50.8) 4000
3 (76.2) 5000
3.3.3 Procedure
1. Clean each sieve to remove any soil left over from previous tests. Use the soft brush on the finer mesh
sieve and the wire brush on the coarser mesh sieve. Take care not to damage the mesh.
2. Measure and record the mass of each sieve, including the bottom pan.
3. Obtain the appropriate amount of sample.
4. Weigh and record the mass of the sample selected.
5. Assemble the sieves in order from largest to smallest so that the coarsest is at the top and the finest is
on the bottom followed by the pan.
6. Place the sample on to the top sieve taking care not to lose any of the mass and place the lid securely
on top.
7. Place the set of sieves in the sieve shaker and adjust the clamps to secure the sieves.
8. Set the shaker on high and set the timer to five minutes.
9. Remove the sieves from the sieve shaker
10. To insure that all the particles passed though the appropriate sieve, tap each sieve over a sheet of paper,
starting with the top sieve. Put any material that falls on to the paper into the next sieve and repeat the
process with the next sieve.
11. Measure and record the mass retained in each sieve.
12. Sum the mass of the material retained on each sieve to verify that there has been no change in the total
mass of the sample. (Note: A mass loss of less than 2% is acceptable.)
3.3.4 Calculations
Determine the weight of soil that is retained on each sieve,Wi.
Calculate the percent of soil that is retained on each sieve (%Ri):
%Ri=WiW 100 (3.1)
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3. Particle Size Analysis of Soils 11
Calculate the percent passing each sieve (%Pi):
%Pi= 100i
k=1
%Ri (3.2)
Plot the percent passing values on the grain size analysis chart provided.
3.4 Particle size analysis of fine grained fraction
3.4.1 Required Materials and Equipment
Stirring apparatus.
Hydrometer, type 151H or 152H.
Sedimentation cylinder, glass cylinder marked for a volume of 1000 ml.
A solution of 40 g/l solution of sodium hexametaphosphate (or Calgon) in distilled water is used as adispersing agent and will be provided
Thermometer, accurate to 1oF (0.5oC).
Graduated beaker to 250 ml capacity.
Timer.
3.4.2 Hydrometer Calibration
The specific gravity of the solution of water and dispersing agent is higher than the specific gravity of distilled
water. This difference must be accounted for when using the equations for percentage of soil remaining in
suspension in section 3.4.4, which were developed for distilled water. In addition, the hydrometers were
calibrated at a constant temperature of 68oF (20oC), which cannot be ensured in our laboratory. Finally,
hydrometers are graduated by the manufacturer to be read at the bottom of the meniscus formed by the
liquid on the stem. However, given the difficulty of conducting a reading at the bottom of the meniscus
through the soil-water suspension, the readings should be taken at thetopof the meniscus and then corrected.
The combined amount of the corrections for these three items is called composite correction and should be
determined before or while conducting the actual test.
For convenience, measurement of the composite correction can be made at a few different temperatures
spanning the range expected during the test, and the result graphed. The correction for intermediate temper-
atures can be estimated using a linear approximation.
Calibration procedure
1. In a graduate cylinder, mix 125 ml of the 40 g/l solution of sodium hexametaphosphate (or Calgon)
and then distilled water up to 1000 ml.
2. Allow the temperature of the solution to become in equilibrium with the temperature in the room.
3. Place the hydrometer in the solution, allow to adjust to the temperature and stop moving.
4. Read the hydrometer at thetopof the meniscus formed on the stem.
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5. The composite correction for hydrometer 151H is the difference between this reading and one; for
hydrometer 152GH it is the difference between the reading and zero.
6. Repeat the measurement in parallel with your hydrometer measurements in the soil-water-dispersing
agent mix, when the room temperature changes.
3.4.3 Procedure
1. Obtain the equivalent of 50 g of air dried soil from the material passing the #200 sieve (do not oven
dry the soil).
2. Determine the hygroscopic water content (due to humidity in the air) using an additional 10-15 g of
soil.
3. Mix the soil to a thick slurry using 125 ml of the distilled water-dispersing agent solution.
4. Mix the slurry in a stirring apparatus for 60 seconds.
5. Transfer to the sedimentation cylinder and fill with distilled water up to the 1000 ml mark.
6. Mix thoroughly: cover the sedimentation cylinder mouth using a rubber glove and your hand and turn
the cylinder upside down and back for 1 minute.
7. Set the cylinder down and quickly start the timer. Take readings using the hydrometer at 4, 15, 30, 60,
90, 120 seconds. Be careful in inserting the hydrometer, so that it will be stabilized as soon as possible
and leave in the suspension for the first 2 minutes. Take readings at thetopof the meniscus.
8. Repeat the mixing process and take a second set of readings for the first 2 minutes.
9. Remove the hydrometer from the suspension and place with a spinning motion in a cylinder filled with
distilled water. To take the following readings, carefully place the hydrometer in the suspension about
20-25 s before the reading is due.
10. Take readings at 5, 15, 30, 60, and 1140 minutes. Place the hydrometer into the distilled water imme-
diately after each reading. After each reading, take the temperature of the suspension by inserting the
thermometer into the suspension.
11. At the end of the experiment, obtain the final dry weight of soil.
3.4.4 Calculations
Hygroscopic correction factor
Determine the hygroscopic correction factor based on the determination of the hygroscopic water content
results:
HygroscopicCF =WsWt
(3.3)
where:Ws is the weight of the soil after oven drying and Wtis the initial weight of the air dry sample.
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3.5 Forms
Sieve Analysis of Coarse Fraction
Sample No. Project
Boring No. Location
Depth
Description of sample
Date Tested by
Total weight of sample
Sieve No. Weight of
Sieve
Weight of
Sieve + Soil
Weight of Soil
Retained
Percentage
Retained
Percentage
Passed
(g) (g) (g) (%) (%)
Total weight of soil (g)
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3. Particle Size Analysis of Soils 15
HydrometerAnalysis
Date
Testedby
SampleNo.
Project
Boring
Depth
(A)Hygroscopicwater
content
(1)CupNo.
(2)Massofcup
(3)Masscup+soil(aird
ry)
(4)Masscup+soil(ovendry)
(5)Massofwater
(6)Massofsoil(ovendry)
(7)Massofsoil(airdry)
(8)Hygroscopicwate
rcontent
(9)Hygroscopiccorrectionfactor
(B)HydrometerAnalys
is
HydrometerType
SpecificGravityofSoil(Gs)
Massofairdrysoil
Calculatemassofovendrysoil
Date
Time
Elapsed
Time
ActualHy-
drometer
Reading
Composite
Correction
Hy
drometer
Re
ading
-
Co
rrection
Temperature
Effective
Hydro
me-
terDepth
Kfromtable
Diameterof
particle,D
Percent
finer
in
suspension
(min)
(rh)
(R
h)
(degreesC)
(mm)
(%)
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3. Particle Size Analysis of Soils 17
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4. Atterberg Limits: Liquid Limit, Plastic Limit, and Plasticity Index of Soils 21
The liquid limit is defined as the water content at which a standard groove cut in the remolded soil sample
by a grooving tool closes over a length of 13 mm (0.5 in) at exactly 25 blows of the liquid limit cup falling
from a height of 10 mm on a hard rubber base. It is very difficult to mix the soil at the right water content,
even after a number of trials. However, if different trials are plotted on a semi-logarithmic scale they should
lie on a straight line and the liquid limit could be taken as the value of water content where the line crosses
the 25 blows mark. For this reason, in a liquid limit test we try to mix the soil at least three different watercontents aiming at blow counts above and below 25.
1. Mix the soil thoroughly with enough distilled water to reach a consistency requiring about 25 to 35
blows of the liquid limit device to close the groove. This is about the consistency of creamy peanut
butter. Keep in mind that it is easier to add water than to take it away, so try to aim for the thicker
consistency.
2. Using a spatula, place a portion of the prepared soil in the cup of the liquid limit device at the point
where the cup rests on the base, squeeze it down, and spread it into the cup to a depth of about 10 mm
at its deepest point, tapering to form an approximately horizontal surface. Take care to eliminate air
bubbles from the soil pat, but form the pat with as few strokes as possible. Keep the unused soil in the
mixing/storage dish. Cover the dish to retain the moisture in the soil.
3. Form a groove in the soil pat by drawing the tool, beveled edge forward, through the soil on a line
joining the highest point to the lowest point on the rim of the cup. When cutting the groove, hold the
grooving tool against the surface of the cup and draw in an arc, maintaining the tool perpendicular to
the surface of the cup throughout its movement.
4. Verify that no crumbs of soil are present on the base or the underside of the cup. Lift and drop the cup
by turning the crank at a rate of approximately 2 drops per second until the two halves of the soil pat
come in contact at the bottom of the groove along a distance of 13mm ( 12
in).
5. Record the number of drops, N, required to close the groove.
6. Quickly remove a slice of soil approximately the width of the spatula, along the groove and including
the portion of the groove in which the soil flowed together, place in a container of known mass, and
obtain a water content. Try to determine water content as soon as possible. The sample is small and
looses water quickly through evaporation.
7. Return the soil remaining in the cup to the mixing cup. Wash and dry the cup and grooving tool and
reattach the cup to the carriage in preparation for the next trial.
8. Remix the entire soil specimen in the dish adding distilled water to increase the water content of the
soil and decrease the number of blows required to close the groove.
9. Repeat steps 1-8 for at least two additional trials producing successively lower numbers of blows to
close the groove. One of the trials shall be for a closure requiring 25 to 35 blows, one for closure
between 20 and 30 blows, and one trial for a closure requiring 15 to 25 blows.
4.3.4 Calculation
Plot the relationship between the water content,wn, and the corresponding number of drops, N, on thegraph provided. Draw the best straight line through the three or more plotted points.
Take the water content corresponding to the intersection of the line with the 25-drop abscissa as theliquid limit of the soil and round to the nearest whole number. Computational methods may be substi-
tuted for the graphical method for fitting a straight line to the data and determining the liquid limit.
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4.4 Determination of Plastic Limit
4.4.1 Required Materials and Equipment
Ground glass plate
Metal rod, 3.2 mm diameter
Balance
Water content cup
4.4.2 Procedure
1. Select about 20 g of soil from the material prepared for the liquid limit test.
2. Reduce the water content of the soil to a consistency at which it can be rolled without sticking to the
hands by spreading or mixing on the glass plate.
3. From this plastic limit specimen, select a 1.5 to 2.0 g portion. Form the selected portion into a ball.
4. Roll the mass between the palm or fingers and the glass plate to form a thread of uniform diameter
throughout its length. Keep rolling until the thread reaches 3.2 mm ( 18
in) diameter. Compare to the
metal rod to determine if the diameter is 3.2 mm. The process should take no more than 2 minutes for
each thread.
5. When the thread has reached a 3.2 mm diameter, break it into pieced and knead together in a ball.
Repeat the rolling and kneading process until the thread crumbles and the soil can no longer be rolled
into a 3.2 mm thread. Do not cheat, be consistent: apply the same rolling pressure during each stage of
the rolling and do not pretend to roll while you wait for the soil to dry and crumble. If the soil breaks
into threads of shorter length, roll each of these shorter pieces into threads 3.2 mm in diameter and
repeat the kneading and rolling process.
6. Collect the broken pieces in a water content cup and cover to prevent further drying while rolling the
next 1.5-2.0 g of soil.
7. Select another 1.5 to 2.0 g portion of soil from the plastic limit specimen and repeat the operations
steps 3-6 until the container has at least 6g of soil.
8. Use the 6 g of soil to obtain the water content according to the procedures in chapter2.
9. Go through the procedure in steps 1-8 until you have obtained two 6 g samples and water content
values. The water contents should not have a difference of more than 1.4%. The plastic limit is the
average of the two water content values.
4.5 Plasticity Index
Calculate the plasticity index as follows:
P I=LL P L (4.1)
where:
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4. Atterberg Limits: Liquid Limit, Plastic Limit, and Plasticity Index of Soils 23
LL = liquid limit
PL = plastic limit
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Atterberg Limits Determination
Sample No. Project
Boring No. Location
DepthDescription of sample
Date Tested by
Liquid Limit Determination
Can No.
Mass of can (g)
Mass of wet soil + can (g)
Mass of dry soil + can (g)
Mass of dry soil (g)
Mass of water (g)
Water content, (%)
No. of drops
LIQUID LIMIT =
PLASTIC LIMIT =PLASTICITY INDEX =
Plastic Limit Determination
Can No.
Mass of can (g)
Mass of wet soil + can (g)
Mass of dry soil + can (g)
Mass of dry soil (g)
Mass of water (g)
Water content, (%)
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Chapter 5
Liquid Limit of Soils using the Drop Cone
Penetrometer
by S.E. Tucker and Z. Medina-Cetina
5.1 Purpose
This apparatus is used commonly in Europe as a replacement for Casagrandes method of determining the
liquid limit of soils. It has been argued that this method is better because it is a static test relying only on
the shear strength of the soil. For certain soils, sometimes it is difficult to obtain repeatable results using the
Casagrande method in a reasonable amount of time. In this method the liquid limit is the water content at
which a cone penetrates the soil for a calibrated distance when it is allowed to free fall for 5 seconds.
5.2 Standard Reference
British Standard 1377: 1990 Part 2
5.3 Determination of Liquid Limit Using Drop Cone Penetrometer
5.3.1 Required Materials and Equipment
Drop cone penetrometer apparatus
200 g of dry soil passing the No 200 sieve
Glass plate
Water content cup
Spatula and mixing tools
5.3.2 Procedure
1. Place the air dried soil in a plastic bag.
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5. Liquid Limit of Soils using the Drop Cone Penetrometer 27
Figure 5.2: Drop cone penetrometer release button.
Figure 5.3: Drop cone penetrometer dial gauge reading.
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14. The first reading should be approximately 15 mm, if it is higher than 17 the soil must be dried and the
test rerun.
15. Retract the cone from the cup and remove approximately 10-15 grams of soil using a spatula so that
the water content may be obtained.
16. Remove the rest of the soil from the cup and remix with the soil on the plate, add very little water tothis (1-2 ml) and mix the soil thoroughly.
17. Clean the cup and repeat steps 6-15 until a minimum of 4 points have been collected, moving from
drier to wetter conditions.
5.3.3 Calculation
Plot the penetration depth versus the water content for each test and fit the data with a best fit line
On the same graph, plot the following points and fit them with a best fit line. This is the calibrationline
Penetration (mm) Water Content(%)20.5 25
21 40
22 72
23 100
Where the calibration line and best fit line for your data intersect is the water content where the samplesliquid limit occurs
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Chapter 6
Classification of Soils According to the
Unified Soil Classification SyStem (USCS)
The Unified Soil Classification System (USCS) is based on the classification scheme developed by Arthur
Casagrande for the United States Army in the 1940s. In its simplest form, it consists in assigning a two- orfour-lettergroup symbolto the soil sample.
6.1 Definitions
fines: soil particles passing the #200 sieve (nominal diameter smaller than 0.075mm).
Coefficient of uniformity:Cu= D60D10
.
Coefficient of curvature:Cc= Cz = D2
30
D10
D60
.
Plasticity Index: PI = LL-PL.
6.2 Initial Classification
6.2.1 Highly Organic Soils
Organic soils are recognized by:
large presence of organic materials;
dark brown, dark gray or black color;
organic odor, especially when wet
very soft consistency
In this case, the material is classified as a peat, with symbol PT, and no further analysis is necessary.
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6.2.2 Non Highly Organic Soils
1. Determine gradation curve by sieve analysis. Use only the material with size smaller than 3in (75mm).
But report the percentage (by weight) of these large particles.
2. If the soil contains less than 5% fines a detailed sieve analysis is required to estimate the values of the
coefficient of uniformity,Cu, and the coefficient of curvature,Ccor Cz.
3. If the soil contains between 5% and 12% fines, the liquid limit and the plastic limit of the fines should
be determined, in addition to the detailed gradation curve andCu,Cc.
4. If the soil contains more than 12% fines the liquid limit and the plastic limit of the fines should be
determined, but it is sufficient to estimate the percentage of soil in the sand and gravel range. The
gradation characteristics,Cu and Cc, are not required.
6.3 Procedure for Classification of Fine Grained Soils
Follow this procedure if 50% or more by weight passes the #200 sieve. This is equivalent to saying that 50%or more by weight has a nominal diameter smaller than 0.075mm.
Figure 6.1: Plasticity chart (from ASTM Standard D2487).
1. Calculate the plasticity index (PI).
2. Compare with the plasticity chart:
LL>50 and PI>A line High plasticity clay (CH)
LL>50 and PI
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6. Classification According to USCS 31
If the soil has organic content: refer to ASTM standard D2487 on the proper procedure. In short,you need to oven dry the specimen to eliminate the organic material and calculate the LL on the
oven dried specimen. The classification is based on the difference between the LL before and
after oven drying.
3. You can add more information on the soil specimen classification after the main group symbol.
If 15% to 30% of the soil had nominal diameter larger than 0.075mm, use with sand or withgravel, depending on which is predominant.
If 30% to 50% of the soil had nominal diameter larger than 0.075mm, use sandy or withgravelly, depending on which is predominant.
6.4 Procedure for Classification of Coarse Grained Soils
Follow this procedure if 50% or more by weight is retained by the #200 sieve. This is equivalent to saying
that 50% or more by weight has a nominal diameter larger than 0.075mm.
1. >50% of the specimen is retained on the #4 sieve (nominal diameter larger than 4.75mm) Gravel(G)
If12% fines and fines are silt based on plasticity chart Silty gravel (GM)
If>12% fines and fines are CL-ML based on plasticity chart Silty clayey gravel (GM-GC)
2. >50% of the specimen is retained between the #4 and the #200 sieves (nominal diameter between0.075 and 4.75mm) Sand (S)
If
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Chapter 7
Visual Classification of Soils
7.1 Purpose
During drilling and sampling operations in the field classification has to be carried out quickly and without
gradation analyses or Atterberg limits. An approximate procedure is then used and the description is notedon the boring log. The initial boring log is often checked later in the laboratory with the help of the retrieved
soil samples. Even in the laboratory a small portion of the samples will be actually tested for classification
purposes. The specimens for classification testing are chosen from the different layers that were identified
during field operations and from previous information, where available. The remaining samples are classified
based on their similarities in the tested samples and visual-manual procedures illustrated below.
7.2 Standard Reference
ASTM D2488- Standard practice for description and identification of soils (visual-manual procedure).
7.3 Terminology
Gravel Particles of rock that will pass a 3 in (75 mm) sieve and be retained on a No. 4 (4.75 mm) sieve with
the following subdivisions:
coarse - passes 3 in (75 mm) sieve and retained on 34
in (19 mm) sieve.
fine - passes a 3.4 in (19 mm) sieve and retained on a No.4 (4.75 mm) sieve.
Sand Particles of rock that will pass a No. 4 (4.75 mm) sieve and be retained on a No. 200 (75 m) sievewith the following subdivisions:
coarse - passes a No. 4 (4.75 mm) and retained on No. 10 (2.00 mm) sieve
medium - Passes a No. 10 (2.00 mm) sieve and is retained on a No. 40 (425m) sieve.
Silt Soil passing a No. 200 (75m) sieve that is non-plastic or very slightly plastic and that exhibits little ofno strength when dry. For classifications, a silt is fine grained soil or the fine grained portion of a soil,
with a plasticity index less than 4, or the plot of plasticity index versus liquid limit falls below the A
line.
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Clay Soil passing a No. 200 (75m) sieve that can be made to exhibit plasticity within a range of watercontents, and that exhibits considerable strength when air-dry. For classifications a clay is a fine
grained soil or a fine grained portion of a soil, with a plasticity index equal to or greater than 4, and
the plot of plasticity index versus liquid limit falls on or above the A line.
Organic Silt A silt with sufficient organic content to influence the soil properties. For classifications, an
organic silt is a soil that would be classified as a silt, except that its liquid limit value after oven drying
is less than 75% of its liquid limit value before oven drying.
Organic Clay A clay with sufficient organic content to influence the soil properties. For classification, an
organic clay is a soil that would be classified as a clay, except that its liquid limit value after oven
drying is less than 75% of its liquid limit value before oven drying.
7.4 Descriptive Information for Soils
Angularity Describe the angularity of the sand (coarse sizes only), gravel, cobbles, and boulders, as angular,
subangular, subrounded, or rounded in accordance with the criteria in table7.1.A range of angularity
may be stated, such as subrounded to rounded.
Shape Describe the shape of gravel, cobbles, and boulders as flat, elongated, or flat and elongated if they
meet the criteria if they meet in table 7.2. Otherwise do not mention the shape. Indicate the fraction
of particles that have that shape; for example: one-third of the gravel is flat.
Color Described the color of the sample when moist.
Odor Describe the odor of the sample if organic or unusual
Moisture Condition Describe the moisture condition as dry, moist, or wet in accordance with the criteria
in table7.3
Consistency For intact fine-grained soil, describe the consistency as very soft, soft, firm, hard, or very hardin accordance with the criteria in table7.4.This observation is inappropriate for soils with significant
amounts of gravel.
Cementation Describe the cementation of intact coarse grained soil as weak, moderate, or strong, in accor-
dance with Table7.5.
Range of particle sizes For gravel and sand components, described the range of particle sizes within each
components. For example, about 20% fine to coarse gravel, about 40% fine to coarse sand.
Maximum particle size Describe the maximum particle size found in the sample for each size classifica-
tion. For example, the largest particle size for sand size particles and the largest particle for gravel size
particles.
Description Criteria
Angular Particles have sharp edges and relatively plane sides with unpolished surfaces
Subangular Particles are similar to angular description but have corners and edges
Subrounded Particles have nearly plane sides but have rounded corners and edges
Rounded Particles have smoothly curved sides and no edges
Table 7.1: Criteria for describing angularity of coarse-grained particles.
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7. Visual Classification of Soils 35
The particle shape shall be described as follows where length, width, and thickness refer to
the greatness, intermediate, and least dimensions of a particle respectively.Description Criteria
Flat Particles with width/thickness>3
Elongated Particles with length/width>3
Flat and Elongated Particles meet criteria for both flat and elongated
Table 7.2: Criteria for describing particle shape.
Description Criteria
Dry Absence of moisture, dusty, dry to the touch
Moist Damp but no visible water
Wet Visible free water, usually soil is below water table
Table 7.3: Criteria for describing moisture conditions.
Description Criteria
Very soft Thumb will penetrate soil more that 1in. (25mm)
Soft Thumb will penetrate soil about 1in. (25mm)
Firm Thumb will indent soil about 1/4in. (6mm)
Hard Thumb will not indent soil but will readily intent with thumbnail
Very Hard Thumbnail will not indent soil
Table 7.4: Criteria for describing consistency
Description Criteria
Weak Crumbles or breaks with handling of little finger pressure
Moderate Crumbles or breaks with considerable finger pressure
Strong Will not crumble with finger pressure
Table 7.5: Criteria for Describing Cementation
Hardness Describe the hardness of coarse sand and larger particles.
7.5 Procedure for Identifying Fine-Grained Soils
Select a representative sample of the material for examination. Remove particles larger than the No. 40 sieve
until a specimen equivalent to about a handful of material is available. Use this specimen for performing the
dry strength, dilatancy, and toughness test.
Dry Strength Select a few dry lumps of about 1/2in. in diameter. Test the strength of the dry pieces by
crushing between the fingers. Note the strength as none, low, medium, high, or very high in accordance
with the criteria in Table7.6. If natural dry lumps are used do not use the results of any of the lumps
that are found to contain particles of coarse sand.
Dilatancy From the specimen select enough material to mold into a ball about 1/2in. in diameter. Mole the
material, adding water if necessary, until it has a soft, but not sticky consistency. Smooth the soil in
the palm of one hand with a small spatula. Shake horizontally, striking the side of the hand vigorously
against the other hand several times. Note the reaction of water appearing on the surface of the soil.
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Description Criteria
None The dry specimen crumbles into powder under mere pressure of handling
Low The dry specimen crumbles into powder with some finger pressure
Medium The dry specimen breaks into pieces or crumbles with considerable finger pressure
High The dry specimen cannot be broken with finger pressure
Very High The dry specimen cannot be broken with thumb and a hard surface
Table 7.6: Criteria for Describing Dry Strength
Squeeze the sample by closing the hand or pinching the soil between the fingers, and note the reaction
as none, slow, or rapid in accordance with the criteria in Table 7.7. The reaction is the speed at which
the water appears while shaking, and disappears while squeezing.
Description Criteria
None No visible change in specimen
Slow Water appears slowly on the surface during shaking and does not disappear or
disappears slowly upon squeezingRapid Water appears quickly during shaking and disappears quickly during squeezing
Table 7.7: Criteria for Describing Dilatancy
Toughness Following the completion of the dilatancy test, the test specimen is shaped into an elongated pat
and rolled by hand on a smooth surface or between the palms into a thread about 1/8in. in diameter.
Fold the threads and reroll repeatedly until the thread crumbles at a diameter of about 1/8in. The thread
will crumble at a diameter of 1/8 in. when the soil is near the plastic limit. Note the pressure required
to roll the thread near the plastic limit. Also, note the strength of the thread. After the thread crumbles,
the pieces should be lumped together and kneaded until the lump crumbles. Note the toughness of the
material during kneading.Describe the toughness of the thread and lump as low, medium or high inaccordance with the criteria in table7.8.
Description Criteria
Low Only slight pressure is required to roll the thread near the plastic limit. The
thread and lump are soft and weak
Medium Medium pressure is required to roll the thread to near the plastic limit. The
thread and lump have medium stiffness.
High Considerable pressure is needed to roll thread near the plastic limit. The thread
and lump have very high stiffness
Table 7.8: Criteria for Describing Toughness
Plasticity On the basis of observations made during the toughness test, describe the plasticity of the material
in accordance with the criteria given in Table 7.9.
7.6 Identification of Inorganic Fine-Grained Soils
Identify the soil as follows:
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7. Visual Classification of Soils 37
Description Criteria
Nonplastic A 1/8in. thread cannot be rolled at any water content
Low The thread can barely be rolled and the lump cannot be formed when drier than
the plastic limit
Medium The thread is easy to roll and not much time is required to reach the plastic
limit. The thread cannot be rolled after reaching the plastic limit. The lumpcrumbles drier than the plastic limit
High It takes considerable time rolling and kneading to reach the plastic limit. The
thread can be rolled several times after reaching the plastic limit. The lump
can be formed without crumbling when drier than the plastic limit.
Table 7.9: Criteria for Describing Plasticity
Soil Symbol Dry Strength Dilatancy Toughness
ML None to Low Slow to rapid Low or thread cannot be formed
CL Medium to High None to Slow Medium
MH Low to Medium None to Slow Medium
CH High toVery High None High
Table 7.10: Identification of Inorganic Fine-Grained Soils from Manual Test
7.7 Procedure for identifying Coarse-Grained Soils
1. The soil is a gravel if the percentage of gravel is estimated to be more than the percentage of sand.
2. The soil is a sand if the percentage of gravel is estimated to be equal to or less than the percentage of
sand.
3. The soil is a clean gravel or clean sand if the percentage of fines is estimated to be 5% of less.
4. Identify the soil as well-graded gravel, GW, or as well-graded sand, SW, if it has a wide range of
particle sizes and substantial amounts of the intermediate particle sizes.
5. Identify the soil as a poorly graded gravel, GP, or as a poorly graded sand, SP, if it consists predom-
inantly of one size (uniformly graded), or it has a wide range of sizes with some intermediate sizes
obviously missing.
6. The soil is either a gravel with fines or a sand with fines if the percentage of fines is estimated to be
15% or more.
7. Identify the soil as a clayey gravel, GC, or a clayey sand, SC, if the fines have the properties of clays.
8. Identify soil as a silty gravel, GM, or a silty sand, SM, if the fines have the properties of a silt.
9. If the soil is estimated to contain 10% fines, give the soil a dual identification using two group symbols.
The first group symbol shall correspond to a clean gravel or sand (GW,GP, SW, SP) and the second
symbol shall correspond to a gravel or sand with fines (GC, GM, SC, SM).
10. The group name shall correspond to the first group symbol plus the words with clay or with silt
to indicate the plasticity characteristics of the fines. For example: well-graded gravel with clay,
GW-GC or poorly graded sand with silt, SP-SM.
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7. Visual Classification of Soils 39
Classification Data SheetSample Classification Comments
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Chapter 8
Compaction Using Standard Effort
8.1 Purpose
Soil placed as engineering fill (embankments, foundation pads, road bases) must be compacted to the se-
lected density and water content to ensure the desired performance and engineering properties such as shearstrength, compressibility, or permeability. Also, foundation soils are often compacted to improve their en-
gineering properties. Laboratory compaction tests provide the basis for determining the percent compaction
and water content needed in the field, and for controlling construction to assure that the target values are
achieved.
In a geotechnical laboratory you would prepare at least four (preferably five) specimens with water
contents bracketing the estimated optimum water content. A specimen having a water content close to
optimum would be prepared first by trial additions of water and mixing and then water contents for the rest
of the specimens would be selected to provide at least two specimens wet and two specimens dry of optimum,
and water contents varying by about 2%, but no more than 4%. In this laboratory exercise each group in your
section will compact one of the specimens at a specific water content, as directed by the laboratory instructor,
and the results from all the groups will be combined later.
The data, when plotted, represents a curvilinear relationship known as the compaction curve. The values
of optimum water content and standard maximum dry unit weight are determined from the compaction curve.
These test methods apply only to soils (materials) that have 20% or less by mass of particles retained on
the No.4 (4.75 mm) sieve.
8.2 Standard Reference
ASTM D 698- Standard test methods for laboratory compaction characteristics of soil using standard effort
(12,400 ft-lbf/ft3 (600 kN-m/m3)).
8.3 Required Materials and Equipment
Mold - A cylindrical metal mold having a 4.000 0.016 in (101.6 0.4 mm) average inside diameter,a height of 4.584 0.018 in (116.4 0.5 mm) and a volume of 0.0333 0.0005f t3 (944 14 cm3).
Rammer - with free fall of 12 0.05 in (304.8 1.3 mm) from the surface of the specimen. The massof the rammer is 5.5 0.02 lbm (2.5 0.01 kg).
Sample extruder - A jack for extruding compacted specimens from the mold.
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Balance - with 1 g readability.
straight edge - for leveling off compacted sample
mixing tools - for mixing the sample of soil with increments of water.
8.4 Procedure
8.4.1 Specimen preparation
1. Obtain from your laboratory instructor a sample of the soil to be tested. You will need approximately
2 kg.
2. Without previously drying the sample, pass it through a No. 4 (4.7 mm) sieve. Determine the water
content of the processed soil. See chapter2for the procedure.
3. Double check the target water content for your specimen with the laboratory instructor.
4. Calculate how much water should be added or subtracted from your sample to obtain the desired water
content. Remember to account for the moisture already present in the sample and use the exact value
for the mass of the soil, not the approximate number.
5. To add water, spray it into the soil during mixing; to remove water, allow the soil to dry in air at ambient
temperature Mix the soil frequently during drying to maintain an even water content distribution.
Thoroughly mix each specimen to ensure even distribution of water throughout and then place in a
separate covered container.
8.4.2 Compaction
1. Determine and record the mass of the mold or mold and base plate.
2. Assemble and secure the mold and collar to the base plate. Place on the concrete floor of the laboratory,
NOTon the counters.
3. The specimen is compacted in 3 layers. Remember that after compaction the layers should be approx-
imately equal in thickness and the last layer should extend above the top of the mold, but no more than1
4in (6 mm). Place approximately 1/3 of the loose soil into the mold for each layer and spread into a
layer of uniform thickness.
4. Compact each layer with 25 blows. In operating the manual rammer, do not lift the guide sleeve
during the rammer upstroke. Hold the guide sleeve steady and within 5o of vertical. Apply the blows
at a uniform rate of approximately 25 blows per minute and in such a manner as to provide complete,uniform coverage of the specimen surface. Usually this is achieved by moving the rammer along the
perimeter of the mold and using 5 blows to cover the whole area. Then the pattern is repeated for 5
times.
5. After compaction of the first two layers, trim any soil remaining on the mold walls or extending above
the compacted surface and include it with the soil for the next layer. Before placing the next layer of
soil scarify the surface of the compacted soil with a knife or other suitable tool to avoid separation of
the layers at the joints later in the test.
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8. Compaction Using Standard Effort 43
6. If the third layer extends above the top of the mold by more than 14
in (6 mm) or below the top of the
compaction mold, the specimen should be discarded.
7. Following compaction of the last layer, remove the collar and base plate from the mold. A knife may
be used to trim the soil adjacent to the collar to loosen the soil from the collar before removal to avoid
disrupting the soil below the top of the mold.
8. Carefully trim the compacted specimen even with the top of the mold by means of the straightedge
scraped across the top of the mold to form a plane surface even with the top of the mold. Initial
trimming of the specimen above the top of the mold with a knife may prevent the soil from tearing
below the top of the mold. Fill any holes in the top surface with unused or trimmed soil from the
specimen, press in with the fingers, and again scrape the straightedge across the top of the mold.
9. Determine and record the mass of the specimen and mold to the nearest gram.
10. Remove the material from the mold using the sample extruder.
11. Obtain a specimen for water content by using the whole specimen or a representative sample. Select a
suitable container and record its weight.
12. Weigh the container and the specimen.
13. Place in the oven for 24 hours. If the entire specimen is used, break it up to facilitate drying.
14. Record the weight of the oven dried specimen in the container.
8.5 Calculations
Post the following information as directed by the laboratory instructor: laboratory section (week day),group (color), date, mass of moist specimen in the mold, mass of mold, water content determination:
mass of moist soil after compaction and can, mass of can, mass of oven dried specimen an can. Seesection8.5for a form to fill.
Calculate the total unit weight of each specimen:
t=Mtg
Vm=
(Msm Mm)g
Vm(8.1)
where:
Mt= mass of moist soil
Msm= mass of the moist specimen and mold
Mm= mass of the moldVm= volume of the mold (944 cm
3)
g= acceleration of gravity (9.807 m/s2)
Calculate water content of each compacted specimen:
w=Mwg
Msg =
(Mwsc Msc)
(Msc M c (8.2)
where:
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Mw = mass of water
Ms= mass of dry soil
Mwsc = mass of wet soil and can
Msc= mass of dry soils and can
Mc= mass of can
w= water content
Calculate dry unit weight:
d= t1 + w
(8.3)
Plot the values and draw the compaction curve as a smooth curve through the points (see example,Fig. 3). Plot dry unit weight to the nearest0.1 lbf
ft3, (0.2 kN
m3)and water content to the nearest 0.1 %.
From the compaction curve, determine the optimum water content and maximum dry unit weight.
Plot the 100% saturation curve.
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Chapter 9
Measuring Suction with the Filter Paper
Method
9.1 Purpose
The filter paper method has long been used in soil science and engineering practice and it has recently been
accepted as an adaptable test method for soil suction measurements because of its advantages over other
suction measurement devices. Basically, the filter paper comes to equilibrium with the soil either through
vapor (total suction measurement) or liquid (matric suction measurement) flow. At equilibrium, the suction
value of the filter paper and the soil will be equal. After equilibrium is established between the filter paper
and the soil, the water content of the filter paper disc is measured. Then, by using filter paper water content
versus suction calibration curve, the corresponding suction value is found from the curve. This is the basic
approach suggested by ASTM Standard Test Method for Measurement of Soil Potential (Suction) Using
Filter Paper (ASTM D 5298). ASTM D 5298 employs a single calibration curve that has been used to infer
both total and matric suction measurements. The ASTM D 5298 calibration curve is a combination of both
wetting and drying curves. Bulut (2001) demonstrates that the wetting and drying suction calibrationcurves do not match, an observation that was also made by Houston et al. (1994). In this test, the wetting
curve as shown in Figure9.2is used because the filter paper becomes wet during the test.
9.2 Soil Suction Concept
In general, porous materials have a fundamental ability to attract and retain water. The existence of this
fundamental property in soils is described in engineering terms as suction, negative stress in the pore water.
In engineering practice, soil suction is composed of two components: matric and osmotic suction (Fredlund
and Rahardjo 1993). The sum of matric and osmotic suction is called total suction. Matric suction comes
from the capillarity, texture, and surface adsorptive forces of the soil. Osmotic suction arises from the
dissolved salts contained in the soil water. This relationship can be formed in an equation as follows:
ht = hm+ h (9.1)
where:
ht= total suction (kPa)
hm= matric suction (kPa)
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hp= osmotic suction (kPa)
Total suction can be calculated using Kelvins equation, which is derived from the ideal gas law using
the principles of thermodynamics and is given as:
ht=
RT
V ln P
Po
(9.2)
where:
ht= total suction
R= universal gas constant
T= absolute temperature
V= molecular volume of water
P/Po = relative humidity
P= partial pressure of pore water vapor
Po = saturation pressure of water vapor over a flat surface of pure water at the same temperature.
If equation9.2is evaluated at a reference temperature of 25o, the following total suction and relative
humidity relationship can be obtained:
ht = 137, 182 ln(P/Po) (9.3)
It can be said, in general, that in a closed system under isothermal conditions the relative humidity may
be associated with the water content of the system such as 100% relative humidity refers to a fully saturated
condition. Therefore, the suction value of a soil sample can be inferred from the relative humidity and
suction relationship if the relative humidity is known. In a closed system, if the water is pure enough, thepartial pressure of the water vapor at equilibrium is equal to the saturated vapor pressure at temperature, T.
However, the partial pressure of the water vapor over a partly saturated soil will be less than the saturation
vapor pressure of pure water due to the soil matrix structure and the free ions and salts contained in the soil
water (Fredlund and Rahardjo 1993).
In engineering practice, soil suction has usually been calculated in pF units (Schofield, 1935) (i.e., suc-
tion in pF = log10|suction in cm of water|). However, soil suction is also currently being represented inlog(kP a) unit system (Fredlund and Rahardjo 1993) (i.e., suction in log(kP a) = log10|suction in kPa|).The relationship between these two systems of units is approximately suction in log(kP a) = suction in pF- 1. Matric suction can be calculated from pressure plate and pressure membrane devices as the difference
between the applied air pressure and water pressure across a porous plate. Matric suction can be formed in a
relationship as follows:
hm= (ua uw) (9.4)
where:
hm= matric suction
ua= applied air pressure
uw = free water pressure at atmospheric condition
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9. Measuring Suction with the Filter Paper Method 49
The osmotic suction of electrolyte solutions, that are usually employed in the calibration of filter papers
and psychrometers, can be calculated using the relationship between osmotic coefficients and osmotic suc-
tion. Osmotic coefficients are readily available in the literature for many different salt solutions. Table 1
gives the osmotic coefficients for several salt solutions. Osmotic coefficients can also be obtained from the
following relationship (Lang 1967):
= wvmw
ln
P
Po
(9.5)
where:
f= osmotic coefficient
v= number of ions from one molecule of salt (i.e., v= 2 for NaCl, KCl, NH4Cland v= 3 forNa2SO4,CaCl2,Na2S2O3,etc.)
m= molality
w= molecular mass of water
w = density of water
The relative humidity term (P/Po) in eq. 9.5 is also known as the activity of water (aw) in physicalchemistry of electrolyte solutions. The combination of eq. 9.2and eq. 9.5gives a useful relationship that
can be adopted to calculate osmotic suctions for different salt solutions:
h = vRTm (9.6)
9.3 Required Materials and Equipment
Schleicher & Schuell No. 589-WH filter paper
Sensitive balance with accuracy of 0.0001 g
Constant temperature container (or cooler)
moisture tins and glass jars
PVC rings, electrical tape
tweezers and gloves
Oven and aluminum block
9.4 Procedure
A testing procedure for total suction measurements using filter papers can be outlined as follows:
1. At least 75% by volume of a glass jar should be filled with the soil; the smaller the empty space
remaining in the glass jar, the smaller the time period that the filter paper and the soil system require
to come to equilibrium.
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2. A ring type support, which has a diameter smaller than filter paper diameter and about 1 to 2cm in
height, is put on top of the soil to provide a non-contact system between the filter paper and the soil.
Care must be taken when selecting the support material; materials that can corrode should be avoided,
plastic or glass type materials are much better for this job.
3. Two filter papers one on top of the other are inserted on the ring using tweezers. The filter papersshould not touch the soil, the inside wall of the jar, and underneath the lid in any way.
4. Then, the glass jar lid is sealed very tightly with plastic tape.
5. Steps 1, 2, 3, and 4 are repeated for every soil sample.
6. After that, the glass jars are put into the ice-chests in a controlled temperature room for equilibrium.
Researchers suggest a minimum equilibrating period of one week (ASTM D 5298; Houston et al., 1994;
Lee 1991). After the equilibration time, the procedure for the filter paper water content measurements can
be as follows:
1. Before removing the glass jar containers from the temperature room, all aluminum cans that are used
for moisture content measurements are weighed to the nearest 0.0001 g. accuracy and recorded.
2. After that, all measurements are carried out by two persons. For example, while one person is opening
the sealed glass jar, the other is putting the filter paper into the aluminum can very quickly (i.e., in a
few seconds) using tweezers.
3. Then, the weights of each can with wet filter paper inside are taken very quickly.
4. Steps 2 and 3 are followed for every glass jar. Then, all cans are put into the oven with the lids half-
open to allow evaporation. All filter papers are kept at 105 5oCtemperature inside the oven for atleast 10 hours.
5. Before taking measurements on the dried filter papers, the cans are closed with their lids and allowed
to equilibrate for about 5 minutes. Then, a can is removed from the oven and put on an aluminum
block (i.e., heat sinker) for about 20 seconds to cool down; the aluminum block functions as a heat
sink and expedites the cooling of the can. After that, the can with the dry filter paper inside is weighed
very quickly. The dry filter paper is taken from the can and the cooled can is weighed again in a few
seconds.
6. Step 5 is repeated for every can.
9.5 Soil Matric Suction Measurements
Soil matric suction measurements are similar to the total suction measurements except instead of inserting
filter papers in a non-contact manner with the soil for total suction testing, a good intimate contact should
be provided between the filter paper and the soil for matric suction measurements. Both matric and total
suction measurements can be performed on the same soil sample in a glass jar as shown in Fig. 1. A testing
procedure for matric suction measurements using filter papers can be outlined as follows:
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9. Measuring Suction with the Filter Paper Method 51
Figure 9.1: Assembly for total and matric suction measurements.
9.6 Procedure
1. A filter paper is sandwiched between two larger size protective filter papers. The filter papers used in
suction measurements are 5.5cm in diameter, so either a filter paper is cut to a smaller diameter and
sandwiched between two 5.5cm papers or bigger diameter (bigger than 5.5cm) filter papers are used
as protection.
2. Then, these sandwiched filter papers are inserted into the soil sample in a very good contact manner
(i.e., as in Fig. 1). An intimate contact between the filter paper and the soil is very important.
3. After that, the soil sample with embedded filter papers is put into the glass jar container. The glass
container is sealed up very tightly with plastic tape.
4. Steps 1, 2, and 3 are repeated for every soil sample.
5. The prepared containers are put into ice-chests in a controlled temperature room for equilibrium.
9.7 Calculations
After obtaining all of the filter paper water contents, figure 9.2 is employed to get total suction and matric
values of the soil samples.
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Figure 9.2: Filter paper wetting calibration curve.
Paper Suction Determination
Sample No. Project
Boring No. Location
Depth
Description of sample
Date Tested by
Total Suction
Paper
Matric Suction
Paper
Container NumberMass of container (g)
Mass of wet paper + container (g)
Mass of wet filter paper (g)
Mass of hot container (g)
Mass of dry filter paper (g)
Mass of water in filter paper (g)
Water content of filter paper (%)
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Chapter 10
Hydraulic Conductivity
10.1 Purpose
Hydraulic conductivity is the parameter that tells us how fast water can flow through soil. This quantity is
measured to determine if a particular soil is a suitable material for a levee, dam or landfill liner, or filter.During this laboratory both the constant head and the falling head methods will be used.
10.2 Standard Reference
ASTM D 2434- Standard test method for permeability of granular soils (constant head).
10.3 Fundamental Test Conditions
The following test conditions are prerequisites for laminar flow of water through granular soils, under
constant-head conditions:
Continuity of flow with no soil volume change during a test.
Flow with the soil voids saturated with water and no air bubbles in the soil voids.
Flow is steady state with no change in hydraulic
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