geotechnical eng ii(s3) lab manual updated 1'2012

8/17/2019 Geotechnical Eng II(S3) LAB MANUAL Updated 1'2012

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Compiled by: Leon Minnies Geotechnical Engineering II Laboratory Manual

Department of Civil Engineering

GEOTECHNICAL ENGINEERING II

(GET200B)

LABORATORY MANUAL

CLASS : ___________________________

GROUP : ___________________________

SURNAME : ___________________________

NAME : ___________________________

STUDENT NUMBER : ___________________________

LECTURER : ___________________________

TECHNICIAN : ___________________________




TABLE OF CONTENTS

1. General...…………………………………………………………………………………………….3 2. Handing in of practical reports..…………………………………………………………………….3

3. The report format..…………….…………………………………………………………………….4 4. Laboratory rules....…………….…………………………………………………………………….4

5. Laboratory project brief ……….…………………………………………………………………….6 6. Laboratory schedule..………….…………………………………………………………………….7

7. Laboratory practical flow chart..…………………………………………………………………….8 8. Civil engineering program outcomes…..…………………………………………………………….8

9. Visual classification of soils…..…………………………………………………………………….10 10. Sieve Analysis………………………...…………………………………………………………...20

11. Liquid limit – Atterberg test.....……………………………………………………………………32 12. Liquid limit – Cone penetrometer test..……………………………………………………………38

13. Plastic limit…………………………...……………………………………………………………43 14. Plastic index...………………………...……………………………………………………………43

15. Shrinkage limit...……………………...……………………………………………………………47 16. Hydrometer test…………………………...………………………………………………………..50

17. Specific gravity of soils..……………...……………………………………………………………57 18. Aashto classification system……...…...……………………………………………………………61

19. Unified classification system..………...……………………………………………………………63 20. Maximum dry density and optimum moisture content(modds).……………………………………67

21. California bearing ratio(CBR) of untreated soils and gravel….……………………………………74 22. Dynamic cone penetrometer test(DCP)……………………….……………………………………87 23. References…………………………………………………………………………………………..92




1. GENERAL

Aims of the Laboratory Sessions

Laboratory sessions in the Department of Civil Engineering have three main aims:

To reinforce or complement the theory covered in lectures through practical examples.

To familiarize students with laboratory and testing procedures

To enhance the generic skills of students including the planning and carrying out of experiments, technicalwriting and critical appraisal of data.

Students will discover the importance of aim 3 as they progress through their professional careers, whether or not it isrelated to engineering.

On entering the laboratory, ensure that the following is done:

1. Have a flow chart (Marked and signed by the lab technician) before commencement. It is yourresponsibility to ensure that the flow chart it signed.

The flow chart must include: The title of the test to be performedThe aim/purpose of the test

The apparatus to be usedThe procedure of the test

*The purpose of the flow chart is to ensure that the test to be carried out is known, why that test is beingperformed, how it is done, and the apparatus to be used are identified. The flow chart is used as a

reference for tests procedures. Failing which you would not be allowed to do your practical, and thus you

will get zero for that practical.

2. Place your bags on the floor, not on the workbenches

3. Sign the register, which will be available for the first 10 minutes, and will be removed afterwards.4. After completing the experiment, clean the work station, apparatus and store away.

The above must be strictly adhered to. If you fail to sign the register you won’t get a mark for the laboratory

session. You will be held responsible for any apparatus not stored, cleaned or returned and the reminder of the

group will lose up to 50%. You will find the laboratory clean and neat. Help to keep it tidy, by cleaning andreturning everything to the cupboard where you have found it.

Attendance to the practical laboratory sessions is compulsory. Student who do not attend, or have made some

alternative arrangements, will not be allowed to hand in any reports. In you being 10 minutes late, you will not beallowed in the laboratory.

If the students want to do their lab sessions earlier or later, the class representative must arrange with the technicianin charge at least 24 hours before the practical time. This will only apply if it fit within the laboratory staff’s

schedule. Failure to prior arrangements will not get any marks for that specific practical.

2. HANDING IN OF PRACTICAL REPORTSCompleted lab practical must be handed in on the dates specified on the handouts. These practical must be in no

later than the time specified. No late hand-ins will be marked. No extensions for handing in or the reports.Allocation of marks for laboratory practical is as follows:

Report = (70%)

- Cover Page 5%




- Content Page 5%

- Flow chart for practical (NB: The Signed flow chart by the lab technician) - 10%- Introduction 5%

- Equipment 5%- Method 15%

- Results and graphs 15%- Analysis 5%

- Comments and Recommendation if any and Conclusion. 5%

Poster (A2 size) = (30%) - Layout - 3.33%

- Photographs - 3.33%- Results - 10%

- Graphs - 10%- Neatness - 3.33%

*NB: Report on what have been done in the laboratory.

Use the forms supplied, failing which, the marks will be lost.

3. THE REPORT FORMATa) Lab Manual

- “Soil Mechanics Laboratory Manual,” by Braja M. Das (2002), Oxford University Press, 6 th Edition,ISBN 0-19-515046-5.

b) Lab Topics

- Determination of Moisture Content- Specific Gravity

- Sieve Analysis- Hydrometer Analysis (24 hours) - Atterberg Limits- Engineering Classification of Soil- Permeability- Compaction Test- Consolidation Test (120 hours) - Unconfined Compression Test- Direct Shear Test- Triaxial Tests

c) Grading

The lab component carries 35% of the overall course grade; 20% for the lab reports and 15% foran exam to be given in the last week of classes.

d) Lab Report




Each report must be individually prepared and submitted. Hand written reports will not be accepted; allreports must be typed. Use Arial or Times New Roman as font type. Do not use an exotic font.

e) Report Elements

The following elements must be included in a lab report: cover page, introduction, equipment, procedure,results and measurements, calculations, discussion and conclusions. The following is a summary ofwhat need to be included in each element.

Cover page

The cover page of the report must contain the following information:your name (in bold), names of lab partners, course title, course ID, experiment title and experiment

date.

Introduction

Include the objective of the experiment. You can simply quote from the lab manual. However, it ispreferred that you state the objective as you understand it in your own words. Describe the visual

appearance of the soil specimen (e.g., brown silty clay). Comment on the importance of the undertakenexperiment in understanding soil behavior.

Equipment

List all equipment and devices used in the experiment.

Procedure

Provide a brief description of the methods and techniques utilized in this experiment. You can use eithera paragraph or a bullet form. The latter is preferable. DO NOT copy the procedure word-for-word from

the laboratory manual!

Results and Measurements

All measurements and observations from the experiment must be recorded in this section. All numericaldata should be recorded to the correct number of significant figures. If results are summarized in a table,make sure that all columns have a heading and that units are clearly depicted.

Calculations

Results should be analyzed in this section. You need to show all necessary calculations. Equations must

be generated using Microsoft Equation, which you can find in Microsoft Word underInsert>Object>Microsoft Equation. Make sure that the units of the answers are appropriate to thequantity sought. Present the solutions to these equations using an appropriate number of significantfigures. For example, in moisture content experiment, the moisture content cannot be 16.753% sinceyour weights are recorded to one decimal point. The moisture content shall be 16.8%.

If needed, figures and tables must be generated using Microsoft Office. Figures must be selfexplanatory; they must include a title, x- and y-axis labels, plotted parameters, symbols, units, a legend if




more than one data set is plotted, etc. Individual data points must be identifiable. As mentionedpreviously, figures must be neat!

Discussion

In this section:- You need to interpret your results and discuss the logical implications in terms of soil behavior.- You need to comment on the variations among replicates. In which measurements or observations

you have the least confidence. How do these variations affect your results? Why are they different?What are the possible sources of error?- If your measurements shall fall within a certain range, what is that range, and how close are you?- You have to also comment on the conduct of the experiment and discuss variations from

specifications and their effect.

The “Discussion” section is worth the most points!

Conclusions

List the main conclusions. Redundancy is OK in this section!

1. Cover page must include the name of the university, campus, department, subject, report title, your nameand student number, group (S1, S3 or S4, full time or part time), lecturer for that subject, and due date.

2. Content page must have the subtitles/headings and page numbers3. Flow chart as mentioned under General.

4. The body of the report as mentioned under handing of practical reports. . Use heading 1 for the headings,and normal for the text. The font must be Times New Roman and font size must be 12. The paragraphs

must be in 1.5 line spacing. The pages must be numbered.

4. LABORATORY RULES1. You are reminded that the rules of the \university also apply in the laboratory.

2. Smoking, eating and drinking are not allowed in the Laboratory3. Know the location of the first aid supply in you Laboratory4. Report all accidents immediately. All injuries, however trivial, must be attended to as soon as possible.

5. When working with inflammable material, have a fire extinguisher at hand.6. Acquaint yourself with the purpose, function and dangers present BEFORE working with a piece of

equipment.7. Do not switch on or operate equipment without authority of lecture or technician. Wear safety clothing

where necessary.8. You should work neatly, quietly and quickly. Soil is dirty. Students must thoroughly clean all laboratory

equipment after completing an experiment and return all equipment pieces to the appropriate cabinets. A penalty in the report grade of 25% will be imposed if this is not done properly. The work place must also be

properly cleaned, and all soil must be discarded as instructed.9. Use data sheets in the laboratory manual to record all data, not notebook or scrap paper. After the

completion of an experiment, neatly complete as much of the computation as possible and have the

instructor sign it before leaving.Before approaching the instructor check that all information has been recorded on the data sheet (group

number, sample number, date. etc.). These sheets must be attached to the laboratory report.




10. Report all breakages and/or defective apparatus to the Technician or Lecture in charge immediately,

otherwise you may be held responsible for their repair or replacement. If an accident is due to carelessnessthe responsible party will be charged for the repair or replacement of the damaged apparatus.

11. Do not work on wet, greasy or oily floor. Grease and oil patches on the floor must be covered with sandand sawdust.

12. Confine yourself to your laboratory concerned,13. Do not work alone. It is good practice to have someone around to shut off the power, etc.

14. Remove all ring and other ornaments from your fingers, hand and neck before starting to work. Clothingmust not hang loose. Tie you hair.

15. Do not skylark in the lab. Never talk to anyone while working, as you cannot work.16. Do not become overconfident and start to take risks.

17. Keep clear of other students. Avoid overcrowding.18. No student is permitted to enter a storeroom.

19. No apparatus may be removed from the Laboratory.20. After use, switch off all apparatus and leave benches in a neat order. Brooms and brushes are available to

clean laboratory.21. Do not forget to return keys that have been issued. The university cannot be held responsible for damage or

loss of private property in the laboratory.22. Each student is required to submit one laboratory report, worth 10% of the final course mark. The

laboratory sessions for which a report is required are marked on the group list on the laboratory schedule.The reports are to be handed in to the Laboratory Technician (Concrete Lab) within 1 week of the

laboratory session. Penalties will apply for late submission, and if any report is submitted more than oneweek late no mark will be given.

23. You are expected to adhere to the University’s Academic Honesty policy. The laboratory report is

expected to be entirely your own work. The following are considered dishonest and will be penalized:

Copying some or all of another student's assignment without acknowledgement

Recycling reports from students from earlier years

Fabrication of data

Knowingly assisting another student in an act of academic dishonesty

24. FAILURE TO COMPLY WITH THE ABOVE RULES WILL RESULT IN DEDUCTION OF

MARKS!!




5. Geotechnical Engineering II Laboratory Project briefThe subject requires the student to complete several practicals. These practicals will be completed as part of a project. A briefintroduction to the practical will be given in class, followed by a demonstration (where required) by the Lab Technician in the

laboratory, and finally the student will take full responsibility for completing the practicals under the supervision of the Lab

Technician and Lab Assistant.

Brief The Cape Peninsula University Of Technology is commissioning the Geotechnical Engineering II students to investigate the

feasibility of building roads and parking area located on the Bellville Campus site. The site is suspect for poor compactionand the presence of clay may also be a possibility.

You are required to complete an individual report detailing your investigation. In order to facilitate the sampling( 60kg) andthe nature of some of the practicals you will perform, the class will split into groups of approximately four students each. Thestudents in the group will appoint a coordinator.

Each group will perform at least the following:

1. Sample the required material on site for the relevant laboratory tests;

2. Perform a sand replacement test and a DCP on site;3. Perform the following tests in the laboratory:

Grading Analysis, Atterberg Limits, Hydrometer Analysis, Modified AASHTO(MODDS) and CBR;

4. Classify the soil according to the Unified Soil Classification System;5. Produce a FLIPFILE (with typed report of EACH PRACTICAL) to the Lab Technician. (Each student shall hand

in an individual report ) in the Assignment cabinet in front of the Concrete Laboratory.

Each report shall include the following:

1. Cover Page(Name & Surname, Stud. nr., Subject Name, Practical heading, Group Name & Name of Lab Technician)2. Objectives of the report;

3. Location of the site;

4. Soil profile;5. Description of each test and results (do not retype the TMH1). Summarise the descriptions noting the key aspects of

the test in not more than 20-25 lines where possible.)6. Flow Chart7. Classification of the soils

8. Calculations & Graphs

9. Interpretation and discussion of the results;

10. Conclusions and recommendations.

Laboratory Students are required to book time in the laboratory in order to complete the project. A FLOW CHART(neatly handwritten/typed) must be submitted to the Lab. Technician and signed by the Lab. Technician before the start of any

practical. The Lab. Technician will also track and monitor the progress of the various groups. Students must follow thelaboratory rules or may be ejected from the laboratory. Booking of the laboratory is essential. It is the responsibility of the

group to manage their project;

Hand-ins 1. A completed typed report to be handed in the following week, before the start of the next practical.2. An A2 size poster(covering all practicals – pictures of activities & apparatus, Results, Calculations & Graphs)

Evaluation The project is 20% of the course mark. The project mark will consist of the following marks:1. Lab Technician’s mark of the individual test hand-ins.

2. Group members evaluation of the contributions of each member. An active group member participating in all agreed

activities will be assigned 100%.3. modification of the project mark by an external moderator.

Lab Technician




6. Laboratory Practical Schedule

WeekFlow

ChartReport

hand-inPractical

TMH1(1986, 2nd ed.)

ReferenceObjectives

3 No No - Introduction & orientation Lab. Technician To demonstrate safety issues in the laboratory

4 Yes Yes

- Sample preparation

- Visual Classification Of Soil

Method A1(a)

ASTM D 2488

Students are expected to understand the importance of

site investigation, planning of sub soil investigation,

interpretation of investigated data todesign suitable foundation system. Visually classify the soil.

5 Yes Yes - Sieve analysis Method A1(a)To introduce the student to the methods of making a

mechanical and hydrometer grain-size analysis of a soil and

to present the resulting data.

6 Yes Yes- Atterberg limits (LL,PL,PI & LS)

Soil Classification (USCS/AASHTO)

Method A2

Method A3

To introduce the student to the procedure for determining the

liquid and plastic limits of a soil.

7 Yes Yes

- Hydrometer

- Specific Gravity of Soils Solids

Method A6

Method A12T

- To introduce the student to the methods of making a

mechanical and hydrometer grain-size analysis of a soil

and to present the resulting data.- To familiarize the student with a general method of

obtaining the specific gravity of a mass of any type of

material composed.

10 Yes Yes- Maximum dry density and optimum

moisture content (Modds)Method A7

To familiarize the student with the laboratory compaction test

and to obtain the moisture - unit weight relationship for agiven compactive effort on a particular soil. To introduce the

student to the procedure for field compaction control tests.

11 Yes Yes - California bearing ratio (CBR)Method A8

To introduce the student to an approximate procedure for

evaluating the shear strength of a cohesive soil & To introduce

the student to a method of evaluating the relative quality ofsubgrade, subbase, and base soils for pavements

12 Yes Yes - Dynamic cone penetrometer (DCP)TMH6

Method ST6

To understand the basics of dynamics – dynamic behaviour ofsoils – effects of dynamic kids and the various

design methods.

13 Yes Yes - Laboratory Flipfile & A2-size PosterTo equip the students with a laboratory profile to showcase

their work to industry.




7. Laboratory Practical Flow Chart

8. Civil Engineering Program Outcomes

The Program Outcomes listed below are expected of all students of the Civil Engineering laboratory program.Below are program outcomes expected to be achieved in this course.

a) an ability to apply knowledge of mathematics, science and engineering; Geotechnical Engineering

b) an ability to design and conduct experiments, as well as to analyze and interpret data; students will

conduct experiments, analyze and interpret data

c) an ability to design a system, component, or process to meet desired needs;

d) an ability to function in multidisciplinary teams;

e) an ability to identify, formulate and solve engineering problems;

f) an understanding of professional and ethical responsibility;g) an ability to communicate effectively; students will work in teams

h) the broad education necessary to understand the impact of engineering solutions in a global andsocietal context;

i) a recognition of the need for and an ability to engage in life-long learning;

j) a knowledge of contemporary issues;

k) An ability to use the techniques, skills and modern engineering tools necessary for engineering

practice; students will use various laboratory equipment including state-of-the-art data acquisition

system; students will analyze data using Excel;

l) proficiency in mathematics through differential equations; probability and statistics; calculus-based

physics and chemistry;

m) proficiency in a minimum of four (4) recognized major civil engineering areas;

Practical Brief

Classification of Soils

- AASHTO / USCS

Collect Soil Sample of 60kg

1. Quartering & Riffling

2. SIEVE ANALYSIS

- 1 x 1200g Sample

5. INDEX PROPERTIES

(LL, PL, PI, SL)

- 48g Sample

6. HYDROMETER

- 100g Sample

- 400ml Solution

Report & PosterPresentation

3. MODDS

- 5 x 7000g Samples

4. CBR

- 3 x 7000g Samples

7. DCP

- To be done on the field




n) an ability to conduct laboratory experiments and to critically analyze and interpret data in more than

one of the recognized major civil engineering areas; in addition to conducting experiments in soil

mechanics, students will learn how the obtained results can influence design and construction decisions

in other civil engineering areas;

o) an ability to perform civil engineering design by means of design experiences integrated throughout the

professional component of the curriculum;

p) an understanding of professional practice issues such as procurement of work; bidding versus quality

based selection processes; how the design professionals and the construction professions interact to

construct a project; the importance of professional licensure and continuing education; and/or other professional practice issues.

Design Activity:

Following instructions in the textbook and appropriate standards, students are required to design

one field experiment.

Engineering Standards:Students will become familiar with TMH 1, ASTM, AASHTO and British standards related to testing in

Geotechnical Engineering.

Realistic Constraints:

Realistic constraints such as economic, manufacturability, ethical, health and safety are discussed

at the appropriate times when experiments are being discussed.

Computer Usage:

Computer usage is required for the report preparation and data analysis. Students will also use

state-of-the-art data acquisition system.




9. VISUAL CLASSIFICATION OF SOILS

Purpose:

Visually classify the soils.

Standard Reference:

ASTM D 2488 - Standard Practice for Description and Identification of Soils (Visual - Manual Procedure)

Significance:

The first step in any geotechnical engineering project is to identify and describe the subsoil condition. Forexample, as soon as a ground is identified as gravel, engineer can immediately form some ideas on the nature of

problems that might be encountered in a tunneling project. In contrast, a soft clay ground is expected to lead to

other types of design and construction considerations. Therefore, it is useful to have a systematic procedure for

identification of soils even in the planning stages of a project.

Soils can be classified into two general categories: (1) coarse grained soils and (2) fine grained soils. Examples

of coarse-grained soils are gravels and sands. Examples of fine-grained soils are silts and clays. Procedures for

visually identifying these two general types of soils are described in the following sections.

Equipment:Magnifying glass (optional)

Identification Procedure:a. Identify the color (e.g. brown, gray, brownish gray), odor (if any) and texture (coarse or fine-

grained) of soil.

b. Identify the major soil constituent (>50% by weight) using Table 1 as coarse gravel, fine gravel,

coarse sand, medium sand, fine sand, or fines.c. Estimate percentages of all other soil constituents using Table 1 and the following terms:

Trace - 0 to 10% by weight

Little - 10 to 20%Some - 20 to 30%

And - 30 to 50%

(Examples: trace fine gravel, little silt, some clay)

d. If the major soil constituent is sand or gravel:

Identify particle distribution. Describe as well graded or poorly graded. Well-graded soil

consists of particle sizes over a wide range. Poorly graded soil consists of particles which are all

about the same size.

Identify particle shape (angular, subangular, rounded, subrounded) using Figure 1 and Table 2.

e. If the major soil constituents are fines, perform the following tests:

Dry strength test: Mold a sample into 1/8" size ball and let it dry. Test the strength of the dry

sample by crushing it between the fingers. Describe the strength as none, low, medium, high orvery high depending on the results of the test as shown in Table 3(a).

Dilatancy Test: Make a sample of soft putty consistency in your palm. Then observe the

reaction during shaking, squeezing (by closing hand) and vigorous tapping. The reaction is

rapid, slow or none according to the test results given in Table 3(b).

During dilatancy test, vibration densifies the silt and water appears on the surface. Now on




squeezing, shear stresses are applied on the densified silt. The dense silt has a tendency for

volume increase or dilatancy due to shear stresses. So the water disappears from the surface.

Moreover, silty soil has a high permeability, so the water moves quickly. In clay, we see no

change, no shiny surface, in other words, no reaction.

Plasticity (or Toughness) Test: Roll the samples into a thread about 1/8" in diameter. Fold the

thread and reroll it repeatedly until the thread crumbles at a diameter of 1/8". Note (a) the

pressure required to roll the thread when it is near crumbling, (b) whether it can support its own

weight, (c) whether it can be molded back into a coherent mass, and (d) whether it is toughduring kneading. Describe the plasticity and toughness according to the criteria in Tables 3(c)and 3(d). A low to medium toughness and non-plastic to low plasticity is the indication that the

soil is silty; otherwise the soil is clayey.

Based on dry strength, dilatancy and toughness, determine soil symbol based on Table 4.

f. Identify moisture condition (dry, moist, wet or saturated) using Table 5.

g. Record visual classification of the soil in the following order: color, major constituent, minor

constituents, particle distribution and particle shape (if major constituent is coarse-grained),

plasticity (if major constituent is fine-grained), moisture content, soil symbol (if majorconstituent is fine-grained).

Examples of coarse-grained soils:

Soil 1: Brown fine gravel, some coarse to fine sand, trace silt, trace clay, well graded,

angular, dry.

Soil 2: Gray coarse sand, trace medium to fine sand, some silt, trace clay, poorly graded,rounded, saturated.

Examples of fine-grained soils:

Soil A: Brown lean clay, trace coarse to fine sand, medium plasticity, moist, CL.

Soil B: Gray clayey silt, trace fine sand, non-plastic, saturated, M

Laboratory Exercise:

You will be given different soil samples. Visually classify these soils. Record all information on the attachedforms.




Table 1. Grain Size Distribution

Soil Constituent Size Limits Familiar Example

Boulder 12 in. (305 mm) or more Larger than basketball

Cobbles 3 in (76 mm) -12 in (305 mm) Grapefruit

Coarse Gravel ¾ in. (19 mm) – 3 in. (76 mm) Orange or Lemon

Fine Gravel 4.75 mm (No.4 Sieve) – ¾ in. (19 mm) Grape or Pea

Coarse Sand2 mm (No.10 Sieve) – 4.75 mm (No. 4

Sieve) Rocksalt

Medium Sand0.42 mm (No. 40 Sieve) – 2 mm (No. 10

Sieve) Sugar, table salt

Fine Sand*0.075 mm (No. 200 Sieve) – 0.42 mm

(No. 40 Sieve) Powdered Sugar

Fines Less than 0.075 mm (No. 200 Sieve) -

*Particles finer than fine sand cannot be discerned with the naked eye at a distance of 8 in (20 cm).

Figure 1. Shape of Coarse-Grained Soil Particles

Rounded Subrounded




Table 2. Criteria for Describing Shape of Coarse-Grained Soil Particles

Description Criteria

AngularParticles have sharp edges and relatively plane sides with unpolished

surfaces.

Subangular Particles are similar to angular description, but have rounded edges.

Subrounded Particles have nearly plane sides, but have well-rounded corners andedges.

Rounded Particles have smoothly curved sides and no edges.

Table (3a). Criteria for Describing Dry Strength


NoneThe dry specimen ball crumbles into powder with the slightest handling

pressure.

Low The dry specimen crumbles into powder with some pressure form fingers.

MediumThe dry specimen breaks into pieces or crumbles with moderate finger

pressure.

HighThe dry specimen cannot be broken with finger pressure. Specimen will

break into pieces between thumb and a hard surface.

Very HighThe dry specimen cannot be broken between the thumb and a hard surface.

Table (3b). Criteria for Describing Dilatancy of a Soil Sample


None There is no visible change in the soil samples.

SlowWater slowly appears and remains on the surface during shaking or water

slowly disappears upon squeezing.

RapidWater quickly appears on the surface during shaking and quickly

disappears upon squeezing.




Table (3c). Criteria for Describing Soil Plasticity


Non-plastic A 1/8” (3-mm) thread cannot be rolled at any water content.

The thread is difficult to roll and a cohesive mass cannot be formed when

Low

drier than the plastic limit.

The thread is easy to roll and little time is needed to reach the plastic limit.

Medium The thread cannot be re-rolled after the plastic limit is reached. The mass

crumbles when it is drier than the plastic limit.

Considerable time is needed, rolling and kneading the sample, to reach

Highthe plastic limit. The thread can be rerolled and reworked several times

before reaching the plastic limit. A mass can be formed when the sample

is drier than the plastic limit

Note: The plastic limit is the water content at which the soil begins to break apart and crumbles when rolledinto threads 1/8” in diameter.

Table (3d). Criteria for Describing Soil Toughness


LowOnly slight pressure is needed to roll the thread to the plastic limit. The

thread and mass are weak and soft.

MediumModerate pressure is needed to roll the thread to near the plastic limit.

The thread and mass have moderate stiffness.

HighSubstantial pressure is needed to roll the thread to near the plastic limit.

The thread and mass are very stiff.

Table 4. Identification of Inorganic Fine-Grained Soils

Soil Symbol Dry Strength Dilatancy Toughness

ML None or 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 Low to Medium

CH High to Very

High

None High

Note: ML = Silt; CL = Lean Clay (low plasticity clay); MH = Elastic Soil; CH = Fat Clay (high plasticity clay).

The terms ‘lean’ and ‘fat’ may not be used in certain geographic regions (midwest).




Table 5. Criteria for Describing Soil Moisture Conditions


Dry Soil is dry to the touch, dusty, a clear absence of moisture

Moist Soil is damp, slight moisture; soil may begin to retain molded

form

Wet Soil is clearly wet; water is visible when sample is squeezed

Saturated Water is easily visible and drains freely from the sample




EXAMPLE DATA

VISUAL SOIL CLASSIFICATION DATA SHEET

Soil Number: Soil A

Classified by: LM

Date: 2010-15-03

1. Color: brown

2. Odor: none 3. Texture: Coarse

4. Major soil constituent: gravel

5. Minor soil constituents: Sand, fines

Approx. % by

Type weight

gravel 60

sand 30 fines 10

6. For coarse-grained soils:

Gradation: well graded Particle Shape: subrounded

7. For fine-grained soils:

Dry Strength: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Dilatancy: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Plasticity: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Toughness: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Soil Symbol: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8. Moisture Condition: dry

Classification:

Brown gravel, some sand, trace fines, well graded, subrounded, dry




EXAMPLE DATA


Soil Number: Soil B

Classified by: LM

Date: 2010-25-03

1. Color: gray

2. Odor: none 3. Texture: coarse

4. Major soil constituent: sand

5. Minor soil constituents: gravel, fines

Approx. % by

Type weight

sand 80

fine gravel 15 fines 5


Gradation: poorly graded Particle Shape: rounded


Dry Strength: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Dilatancy: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Plasticity: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Toughness: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Soil Symbol: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8. Moisture Condition: dry

Classification:

Gray sand, little fine gravel, trace fines, poorly graded, rounded, dry




EXAMPLE DATA


Soil Number: Soil C

Classified by: LM

Date: 2010-27-03

1. Color: gray

2. Odor: none 3. Texture: fine grained

4. Major soil constituent: fines

5. Minor soil constituents: fine sand

Approx. % by

Type weight

fines 95

fine sand 5. . . . . . . . . . . . . .


Gradation: . . . . . . . . . . . . . Particle Shape: . . . . . . . . . . . . .


Dry Strength: high

Dilatancy: none Plasticity: medium

Toughness: medium

Soil Symbol: CL

8. Moisture Condition: moist

Classification:

Gray silty clay, trace fine sand, medium plasticity, moist, rounded, CL




BLANK DATA SHEET


Soil Number: _________________

Classified by: _________________

Date: _________________

1. Color: ____________

2. Odor: ____________

3. Texture: ____________

4. Major soil constituent: ____________

5. Minor soil constituents: ____________

Approx. % by

Type weight

____________ ____________

____________ ____________

____________ ____________


Gradation: ____________Particle Shape: ____________


Dry Strength: ____________

Dilatancy: ____________

Plasticity: ____________

Toughness: ____________

Soil Symbol: ____________

8. Moisture Condition: ____________

Classification:

INSERT PICTURE

OF

SOIL SAMPLE,

HERE!!




10. THE WET PREPARATION AND SIEVE ANALYSIS OF

GRAVEL, SAND AND SOIL SAMPLES(METHOD A1)

1. SCOPEThe preparation of a gravel, sand or soil sample involves the quantitative separation of

the soil fines portion, i.e. the material passing the 0,425 mm sieve, from the coarser

portion as well as the sieve analysis of the coarser portion. The soil fines are required

for the mechanical analysis and for the determination of the Atterberg constants andthe linear shrinkage.

OBJECTIVE

To determine the grain – size distribution of soils.

2. APPARATUS

2.1 A riffler with 25,0mm openings.

2.2 The following test sieves, complying with SABS 197, with sieves larger than 4,75mm of perforated

plate and sieves 4,75mm and smaller of wire mesh:

(a) A 19,0mm sieve, recommended diameter 450mm.

(b) A 63,0mm, 53,0mm, 37,5mm, 26,5mm and 19,0mm sieve, recommended diameter 300mm, witha pan.

(c) A 63,0mm, 53,0mm, 37,5mm, 26,5mm, 19,0mm, 13,2mm, 4,75mm, 2,0mm and 0,425mm sieve,

recommended diameter 200mm, with pan and cover.

2.3 A mechanical sieve shaker (optional).

2.4 A balance with a pan to weigh up to 5 kg, accurate to 19.

2.5 Basins and pans:

(a) A basin, about 500 mm in diameter.

(b) Basins, about 350 mm in diameter.(c) Square pans, about 300 mm square at the top, tapering to 250 mm square at the bottom.

2.6 A 150mm nominal diameter iron mortar and pestle and a rubber-tipped pestle.

2.7 Hotplates or ring gas-burners.2.8 A drying oven, thermostatically controlled and capable of maintaining a temperature of 105 to 110°C.2.9 Brushes:

(a) A brass or copper wire brush, measuring about 50mm x 25mm with bristles not more than 25

mm long.

(b) A hard-bristle nail-brush, measuring about 80mmx25mm.

2.10 A supply tank for distilled water

2.11 Paper bags, 1 kg capacity.

2.12 A steel-bladed spatula, with a blade about 100 mm long




Sieve Analysis Apparatus: A) Sieve aperture sizes, B) Dry oven, C) Sieve shaker, D) Mortar & Tray, E)Rubber pestle, [F) Balance

As per figure above:

Stack of Sieve Aperture sizes (including the cover and pan) Electronic Balance (decimal reading to 0.01 g)

Rubber pestle, mortar (for crushing the soil if lumped), and brush

Mechanical sieve vibrator (shaker)

Oven Dry (thermostatically controlled temperature)

3. TEST PROCEDURE

3.1 Size of test sampleThe size of the test sample will depend on the amount of soil fines (i.e. the portion passing the 0,425

mm sieve) present in the material. At least 300g of soil fines are required for the mechanical analysisand for the determination of the soil constants and the linear shrinkage. In the case of a soil which

consists mostly of soil fines, a test sample of about 400g should prove adequate, whilst in the case of a

gravel containing, for example, only 10 per cent of soil fines, the required quantity of material will be

approximately 3 000 to4 000g. The sample received from the field should, therefore, be quartered down by means of a riffler to

the required size.

3.2 Quartering3.2.1 The sample is emptied from the sample bag into one or more of the riffler pans. The material is

then poured through the riffler by slowly tilting the pan so that the material flows in an even

stream over the width of the pan. At the same time the pan is moved to and fro along the full

length of the riffler ensuring an even flow of the material. The process is repeated with the

contents of one of the pans under the riffler until a sample of the required size is obtained.3.2.2 The test sample should, of course, be representative of the field sample and it is important to

ensure a free flow of the material through the openings of the riffler. Problems arise in the case




of samples containing coarse aggregate, large soil clods and/or large lumps of wet clay. As these

will lodge in or on the openings of the riffler, they should first be removed by sieving before the

material is passed through the riffler. In such cases, the following procedure should be used:

3.2.2.1 The sample is poured onto the 450mm diameter, 19,0 mm opening sieve which is

placed in a 500 mm basin. Any large soil aggregations or clods retained on the

sieve should be disintegrated in the mortar by applying pressure to the pestle or

by tamping very lightly. The disintegrated material is added to the portion passing

the sieve, which is then subdivided in the riffler as described above. The

aggregate retained on the sieve is sub-divided by the method of coning andquartering. This is accomplished by forming the material into a cone which is

pressed flat and by dividing into tour quadrants, rejecting the two opposite

quadrants and continuing the process of coning and quartering until a portion ofthe required size is obtained. If the material passing the 19,0 mm sieve is divided

by the riffler to obtain a portion of say a quarter of the field sample, the coarse

aggregate is divided an equal number of times. That portion of the coarse

aggregate is now added to the portion passing the 19,0 mm sieve and this then

constitutes the test sample which is considered to be representative of the sample

as received from the field (see 5.1).

3.2.2.2 There is normally no need to dry the material before quartering, but if the sample

contains large lumps of wet clay which cannot be dis-integrated it should first bedried in an oven at a temperature not exceeding 110°C. The clods are then

disintegrated in the mortar so as to pass the 19,0 mm sieve after which the

material is divided in the riffler in the same manner as described above.

3.3 Dry Sieving

The material should be sufficiently dry so that it can be sieved through the 0,425mm sieve withoutclogging the sieve. Therefore, if the quartered test sample is wet or damp, it should be dried in an oven

at a temperature not exceeding °C. The sample is then weighed and sieved through a 0,425 mm sieve. It

is desirable to place a 2.00mm or a 4,75 mm sieve above the 0,425 mm sieve to act as a guard for the

finer sieve. The material retained on the 0,425 mm sieve is transferred to a mortar and by rubbing with a

rubber-tipped pestle, most of the soil aggregations are disintegrated and at the same time most of the soiladhering to the aggregate is dislodged. The material is then sieved again through the 0,425 mm sieve.

As much of the soil fines as possible should be separated in this way. The soil fines thus obtained are

transferred to a paper bag which is placed in a drying oven at a temperature of 105 -110°C.

3.4 Boiling and Washing

The material retained on the 0,425 mm sieve is transferred to a tin basin, covered with distilled ordeionised water and brought to the boil.It is boiled vigorously for about one minute and then allowed to

cool. If necessary, the material should then be worked thoroughly by hand in the water so as to ensurethat all soil aggregations are disintegrated and that all the soil adhering to the aggregate has been

loosened. The larger aggregate is removed and washed with distilled water on the 0,425mm sieve held

over a clean basin until the wash water is clear. It is again desirable to protect the sieve by fitting a

coarser sieve above it. The clean aggregate is then transferred to a square pan. The finer material

remaining in the boiling basin is then stirred vigorously and the mass is poured quantitatively on to the

0,425 mm sieve held over the second basin. Both the sieve and the basin from which the material is

poured should be agitated vigorously during pouring. The basin is then washed clean with a jet of

distilled or deionised water whilst still being held over the sieve. The material on the sieve is washed by

directing a jet of distilled or deionised water on to the material until the wash water is clean. The sieve

should be agitated whilst washing. If the soil is very clayey, the sieve should be placed in the water and

the material on the sieve agitated by rubbing with the fingers against the side of the sieve as this will

speed-up the washing process. The sieve should also be raised and lowered in the wash water as this

facilitates washing and keeps the amount of wash water required to a minimum. The washed material is




transferred to the square pan by inverting the sieve and washing down with water. The water in the pan

is poured off carefully and the material dried in an oven at a temperature of 105 to 110°C.

3.5 Drying and disintegration of finesThe suspension containing the fines washed through the 0,425 mm sieve is boiled down to a slurry

which is then dried in an oven at a temperature of 105 to 110°C. The dried soil in the bottom of the

basin is loosened with a stiff wire brush or with a spatula in the case of clayey soils. The material

adhering to the sides of the basin is brushed down and the slurry is disintegrated as far as possible with

the brush. The material is sieved through the 0,425 mm sieve and clods retained on the sieve aredisintegrated in the mortar with a rubber-tipped pestle, or if too hard, with the iron pestle. It is notnecessary to crush very finely,just sufficiently to enable all the material to pass the 0,425 mm sieve. The

soil fines are added to the portion obtained by dry sieving as described in 3.3.

3.6 Sieve analysisAfter drying, the material retained on the 0,425 mm sieve is sieved through a nest of sieves consisting of

the following: 63,0 mm, 53,0 mm, 37,5 mm, 26,5 mm, 19,0 mm, 13,2 mm, 4,75 mm, 2,0 mm and 0,425

mm. The sieving should be thorough and be done either by hand or by means of a mechanical sieve

shaker. On no account should any sieve be overloaded as some of the fine material may be kept back if

the layer on the sieve is too deep. If necessary, the material should be divided into fractions which are

then sieved separately. After sieving, the material retained on each sieve is weighed and the massesrecorded in the appropriate column of Form A1/1 (or a similar form). Weighing should be accurate to

the nearest 1 gram. The material passing the 0,425 mm sieve is added to the soil fines portions obtained

by dry sieving and by washing. All this material is now transferred to the scoop of the scale (or other

similar container) where it is thoroughly mixed by stirring. It is then weighed and returned to the paper

bag ready for the mechanical analysis and for the determination of the Atterberg constants and the linear

shrinkage.

4 CALCULATIONS

The mass of each fraction retained between two sieves and the fraction passing the 0,425 mm sieve is

converted to a percentage of the total mass of the dry material. (The mass of the original test sample is

merely determined to serve as a check that no serious error has been made. This latter mass willnormally be some- what higher than that of the dry material due to the presence of hygroscopic

moisture.) The percentage retained on each sieve is then converted to a percentage passing the sieve.

The percentages are calculated and reported to the nearest whole number on the appended Form A

and/or plotted on a suitable grading sheet such as the Form B.

5 NOTES5.1 In cases where the quantity of the different sizes of coarse aggregate in the field sample is such

that it cannot be subdivided into a reasonably representative portion by coning and quartering,the sieve analysis carried out on the relatively small test sample will be far from accurate. A

sieve analysis is, therefore, carried out on all the aggregate retained on the 19,0 mm sieve using a

nest of 300 mm diameter sieves with openings from 63,0 mm to 19,0 mm. Seeing that in this

case the aggregate is not subjected to the usual boiling and washing, care should be taken to

remove any soil adhering to the aggregate before the sieve analysis is carried out. The actual test

sample will now only consist of a portion of the material passing the 19,0 mm sieve and it is,

therefore, important to remember that the above sieve analysis should be corrected, as it is

carried out on al I the coarse aggregate in the field sample. If the test sample consists of an

eighth of the field sample, the masses of the aggregate fractions retained on the sieves should be

divided by eight. After the sieve analysis, all the coarse aggregate is returned to the sample bag,

i.e. it is combined with the unused portion of the material passing the 19,0mm sieve. It should

now be remembered that the material in the bag is no longer a representative sample, and should

it be necessary to repeat the test, allowance must be made in the subsequent calculations.




5.2 The soil fines obtained from sieving will contain hygroscopic moisture, except where the test

sample was oven-dried prior to sieving. It is not considered necessary to dry the fines to constant

mass, but by keeping the paper bag with the fines in the oven for at least the time required to

complete all the subsequent processes, some of the moisture will be driven off. Such soil is

considered to be sufficiently dry for the determination of the percentage passing through a 0,075

mm sieve and for hydrometer analysis (see Method A5 and Method A6).

5.3 As an alternative to boiling, the material may be left to soak overnight.

5.4 Care should be taken to ensure that the soil is not overheated as this may change its

characteristics. The basin should, therefore, be removed timeously from the hot plate or gas burner, i.e. whilst the material is still in the form of a thin slurry.

5.5 Clean rain water may be used instead of distilled or deionised water.

5.6 It is essential that the particle size should not be altered during the preparation. Only friabledecomposed material and soil clods should be dis-integrated. The extent to which decomposed

material is to be disintegrated cannot be specified and must be left to the discretion of the

operator. Material from compacted layers in the road should be prepared without disintegrating

the decomposed material.

CALCULATIONS, PLOTTING AND QUESTIONS:1. Calculate particle size distribution curve and tabulate it in to the form 1.1.

2. Plot the grain size distribution. Use form 1.2. Is the sample well graded, gap graded or3. uniform? Explain.

4. Calculate Cc and Cu and classify the soil according to the Unified Classification System.

5. Would you expect the particle size distribution to be affected by the treatment given to

the soil prior to sieving?

6. What are the uses of the analysis?

7. Why do you use logarithmic plot for the distribution?8. Why is sieve analysis confined to coarse grained soils?




SAMPLE NO. : . . . . . . . . . . . . . . . . . . . . . . . . . DATE : . . . . . . . . . . . . . . . . .

DRY MASS : . . . . . . . . . . . . . . . . . . . . . . . . PAN NO. : . . . . . . . . . . . . . .

TESTED BY : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SIEVE

NUMBER

SIEVE

SIZES

(mm)

MASS RETAINED(g)

PERCENTAGE

RETAINED

(%)

PERCENTAGE

PASSING

(%)

3 inches 75.0

2 ½ inches 63.0

2.12 inches 53.0

1 ½ inches 37.5

1.06 inches 26.5

¾ inches 19.0

0.530 inches 13.2

3/8 inches 9.5

0.265 inches 6.7

4 4.75

8 2.36

10 2.00

16 1.18

30 0.600

40 0.425

50 0.300

100 0.150

200 0.075

< 200 / Pan < 0.075 / Pan

TOTAL =

Form A




EXAMPLE – GRAIN SIZE DISTRIBUTION

The Calculations

Both calculation methods taken into account with an example of test sheet result:-Calculation following BS 1377: Part 2 1990:

Calculation following ASTM D-422:

The Results Documentation

Draw graph of log sieve size vs % finer. The graph is known as grading curve. Corresponding to 10%, 30% and60% finer, obtain diameters from graph these are D10, D30, D60, using these obtain Cc and Cu which furtherrepresent how well the soil is graded i.e whether the soil is well-graded, gap-graded or poorly graded.




The Graphs

Graph for BS 1377: Part 2 1990:

British Standard Sieve SizesGraph for ASTM D-422:

US Standard Sieve Sizes

Referring to the graph;

Uniformity Coefficient, Cu = D60 / D10 = 0.9 / 0.16 = 5.625

Coefficient of Gradation, Cc = (D30)2

/ (D60 x D10) = (0.37)2

/ (0.9 x 0.16) = 0.95




Things to Remember

A few thing remember during the testing:

Make sure the sieve aperture in dry condition and properly cleaned from any particles by poke them out using

brush before commencing the test.

Make sure to double check the stack of sieve aperture sizes arrangement in order before shaking begins.

Make sure the balance have an adequate battery for a long run (if lots of soil sample to be test).

The sieve shaker should be in good condition as well for a long run.

The oven-dry and the balance calibration certificate still valid (haven’t due yet) for an accurate results.

Do not shake the soil sample with the shaker for too long as the finer particles could easily lost. For moreaccurate results especially doing some research or independent lab test, manual approach is recommended.The sieve analysis of soil test above is applicable not only to soil samples but can be tested upon aggregate,

cement, and sand samples. The procedure would be the same as well as the calculation method and the graph plotting. Happy testing…




Form B




Figure 10.1 – Typical particle size distribution curves




Figure 10.2 – Cumulative Particle-Size Plot




11. LIQUID LIMIT

DEFINITION

The Liquid limit is the moisture content at which the soil passes from the plastic to the liquid state as

determined by the Liquid Limit test.

11.1 Atterberg test

THE DETERMINATION OF THE LIQUID LIMIT OF SOILS BY MEANS OF THE FLOW CURVEMETHOD(METHOD A3)

SCOPE:This lab is performed to determine the plastic and liquid limits of a fine-grained soil. The liquid limit (LL) is

arbitrarily defined as the water content, in percent, at which a pat of soil in a standard cup and cut by a grooveof standard dimensions will flow together at the base of the groove for a distance of 13 mm (1/2 in.) when

subjected to 25 shocks from the cup being dropped 10 mm in a standard liquid limit apparatus operated at a rateof two shocks per second.

OBJECTIVE

To determine the moisture content at which a cohesive soil will pass from a liquid state to a plastic state.

APPARATUS

1. Casagrande liquid limit device

2. Grooving tool

3. Calibrating block (25x25x10)mm

4. Moisture cans

5. Porcelain evaporating dish

6. Spatula

7. Oven set at 105°C

8. Balance sensitive up to 0.01g9. Plastic squeeze bottle10. Paper towels

Figure 11.1 – Atterberg Liquid Limit device




Figures A,B,C,D – Equipment for Liquid Limit test




3. TEST PROCEDURE:

(1) Take roughly 48g of the soil and place it into the porcelain dish.

Assume that the soil was previously passed though a 0.425mm sieve, air-dried, and then pulverized.

Thoroughly mix the soil with a small amount of distilled water until it appears as a smooth uniform

paste. Cover the dish with cellophane to prevent moisture from escaping.

(2) Weigh four of the empty moisture cans with their lids, and record the respective weights and can

numbers on the data sheet.

(3) Adjust the liquid limit apparatus by checking the height of drop of the cup. The point on the cup that

comes in contact with the base should rise to a height of 10 mm. The block on the end of the groovingtool is 10 mm high and should be used as a gage. Practice using the cup and determine the correct rate torotate the crank so that the cup drops approximately two times per second.

(4) Place ¾ of the previously mixed soil into the cup of the liquid limit apparatus at the point where the cuprests on the base. Squeeze the soil down to eliminate air pockets and spread it into the cup to a depth of

about 10 mm at its deepest point. The soil pat should form an approximately horizontal surface (See

Photo B).

(5) Use the grooving tool carefully cut a clean straight groove down the center of the cup. The tool should

remain perpendicular to the surface of the cup as groove is being made. Use extreme care to prevent

sliding the soil relative to the surface of the cup (See Photo C).

(6) Make sure that the base of the apparatus below the cup and the underside of the cup is clean of soil.

Turn the crank of the apparatus at a rate of approximately two drops per second and count the number ofdrops, N, it takes to make the two halves of the soil pat come into contact at the bottom of the groove

along a distance of 13 mm (1/2 in.) (See Photo D). If the number of drops exceeds 50, then go directly

to step eight and do not record the number of drops, otherwise, record the number of drops on the data

sheet.

(7) Take a sample, using the spatula, from edge to edge of the soil pat.

The sample should include the soil on both sides of where the groove came into contact. Place the soilinto a moisture can cover it. Immediately weigh the moisture can containing the soil, record its mass,

remove the lid, and place the can into the oven. Leave the moisture can in the oven for at least 16 hours.

Place the soil remaining in the cup into the porcelain dish. Clean and dry the cup on the apparatus and

the grooving tool.

(8) Remix the entire soil specimen in the porcelain dish. Add a small amount of distilled water to increasethe water content so that the number of drops required to close the groove decrease.

(9) Repeat steps six, seven, and eight for at least two additional trials producing successively lower

numbers of drops to close the groove. One of the trials shall be for a closure requiring 28 to 35 drops,

one for closure between 22 and 28 drops, and one trial for a closure requiring 15 to 22 drops. Determinethe water content from each trial by using the same method used in the first laboratory. Remember to

use the same balance for all weighing.

4. CALCULATIONS

4.1 Moisture Content(%)

The moisture content of the soil is expressed as a percentage of the mass of the oven- dried soil and is

calculated as follows:

()

The percentages are calculated and reported to the nearest whole number on the appended Form C

and/or plotted on a suitable grading sheet such as the Form D OR Form A2/1.




Analysis:

Liquid Limit:(1) Calculate the water content of each of the liquid limit moisture cans after they have been in the oven for

at least 16 hours.

(2) Plot the number of drops, N, (on the log scale) versus the water content (w). Draw the best-fit straight

line through the plotted points and determine the liquid limit (LL) as the water content at 25 drops as

shown in figure below.

CALCULATIONS, PLOTTING AND QUESTIONS:

1. Calculate the moisture content of both samples tested. Form C may be used.

2. Calculate the plasticity index of the soil.

3. Draw the locations of the plastic and liquid limit on a PLASTICITY CHART. Indicate significant valuesand material description group.

4. What is the engineering significance of the consistency limits and for which soil it is especially important?5. Why are the tests only carried out on material passing through a 0.425mm test sieve?

6. Classify the soil according to the AASHTO CLASSIFICATION SYSTEM or the UNIFIEDCLASSIFICATION SYSTEM. What problems (if there are any) do you expect when using this engineering

practice?

Figure 11.2 – Liquid limit & Plasticity Chart Example




Date: . . . . . . . . . . . . . . . . . . . . . . . . . . .

Project Name: . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Sample Number: . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Sample Description: . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Liquid Limit Determination using CASAGRANDE TEST METHOD

Sample no. 1 2 3 4

Moisture can and lid number

MC = Mass of empty, clean can + lid (grams)

MCMS = Mass of can, lid, and moist soil

(grams)

MCDS = Mass of can, lid, and dry soil (grams)

MS = Mass of soil solids (grams)

MW = Mass of pore water (grams)

w = Water content, w% No. of drops (N)

Plastic Limit Determination

Sample no. 1 2 3




(grams)




w = Water content, w%

Plastic Limit (PL) = Average w % =

Form C




0 10 20 30 40 50

No. of Blows, N

Final Results:

Liquid Limit =

Plastic Limit =

Plasticity Index =

Form D – Atterberg Device graph sheet




11.2 Liquid Limit using Cone Penetrometer(BS 1377: Part 2:1990)

SCOPE

This method describes the procedure for the determination of the Liquid Limit of soils and granular materials.

APPARATUS- Cone penetrometer with standard cone of mass 80 gr. sees fig. 1

- sample cup of diameter 55 mm and 40 mm deep

- Flat glass plate about 500mm square.- 2 spatulas

- wash bottle

- drying oven

- mass balance accurate to 0.01 g

Fig.11.3 - Cone Penetrometer apparatus

1. Sample preparation

Wherever possible the test shall be carried out on soil in its natural state. With many clay soils it is practicable

and shall be permissible to remove by hand any coarse particles present, i.e. particles retained on a 425µm test

sieve. Otherwise these particles shall removed by wet sieving.

2. Sieve procedure-Take a sample of the soil of sufficient size to give a test specimen weighing at least 300 g. which passes the

425 µm test sieve.

-Take a representative sample and determine its moisture content, Wn (in %)

-Weight the remainder of the sample to an accuracy of within 0.01 g (M6)

-Place the sample in a container under just enough distilled water to submerge it.

-Stir the mixture until it forms a slurry.

-Sieve the slurry through the 425 µm sieve with the minimum amount of distilled water until the water passing

is virtually clear.-Collect the material retained on the 425 µm sieve, dry it at 105 °C and weigh it to an accuracy of within 0.01 g

(M7).




-Collect the fines in a receiver or large container if necessary, and let the fine particles settle.

-After a suitable interval pour off any clear water above the suspension, and let it dry (warm air) until it forms a

stiff paste.

3. CALCULATION:From the sieved soil calculate the dry mass, M

d(in g), of the initial sample from the equation:

WhereWn

is the moisture content (in %)

M6 is the mass of particles retained on 425 µm sieve (in g).

Where

M7 is the dry mass of particles passing the 425 µm sieve (in g)

4. PROCEDURE- Thoroughly mix the sample on the glass plate using two spatulas, and if necessary add distilled water, to form

a plastic material- Place the paste into an airtight container, and leave it standing for a curing period of 24 hour, or overnight, to

allow water to permeate through the soil mass. For soil of low clay content, such as very silty soils, the

curing period may be omitted.

- Remove the soil from the container and remix with the spatulas for at least 10 min. Some soils (heavy clays)

up to 40 min.

- fill the sample cup with the soil and trim off excess material with the spatula to form a smooth even surface being careful not to trap any air bubbles

- bring the point of the cone to the surface of the sample lower the dial gauge pointer to the top of the cone andset the gauge on zero

- release the cone pressing the release button for 5 seconds

- lower the pointer to the new position of the cone- Take a reading to the nearest 0.1 mm, it should be approximately 15 mm for the first test.

- Lift out the cone and clear it carefully. Add a little more wet soil to the cup and take a second reading. If the

second cone penetration differs from the first by less than o.5 mm, the

- Average value is recorded, and the moister content is measured. If the second penetration is between 0.5 and 1

mm different from the first, a third test is carried out, and provided the overall range does not exceed 1mm,

the average of the three penetrations is recorded and the moisture content is measured. If the overall range

exceed 1mm, the soil is removed from the cup and remixed, and the test is repeated.

- take a sample of approximately 10 gram from the cup and determine its moisture content

- To the remainder of the material add some distilled water and repeat the above procedure. This is done at least

three more times to get a range (min. 4) of penetration values from about 15mm to 25 mm.

- N.B. One must be careful not to add too much water at one time.

5. CalculationThe moisture contents determined are plotted against the respective penetration depth, both on a linear scale.

The liquid limit is defined as that moisture content where the cone penetrates 20 mm into the sample. Thisvalue is interpolated from a graph. See fig. 3.2.2.

6. Reporting

-The liquid limit is expressed to the nearest whole number.

-Treatment of the soil.

-The percentage material passes the 425 mµ sieve, if it was sieved.




1 2 3 4 PL PL

Penetration (mm)16.1 17.6 19.3 21.3

Wet mass + tin

(g)20.70 19.60

M/C (%)50.0 52.1 54.1 57.0

Dry mass + tin

(g)18.70 17.80

Tin (g) 8.10 8.40

M/C (%) 18.9 19.1

Final Results:

LL = 55%Pl = 19%PI = 36%

Fig 11.3 – Liquid Limit using Cone Penetrometer Example

14.0

16.0

18.0

20.0

22.0

24.0

50.0 51.0 52.0 53.0 54.0 55.0 56.0 57.0 58.0 59.0 60.0

C

o n e p e n e t r a t i o n ( m m )

Moisture Content (%)




1 2 3 4 PL - 1 PL - 2

Penetration (mm)

Wet mass + tin

(g)

M/C (%)

Dry mass + tin

(g)

Tin (g)

M/C (%)

Final Results:

LL =

Pl =PI =

Form E – Cone Penetrometer graph sheet




Date: . . . . . . . . . . . . . . . . . . . . . . . . . . .

Project Name: . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Sample Number: . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Sample Description: . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Liquid Limit Determination using CONE PENETRATION METHOD

Sample no. 1 2 3 4




(grams)




w = Water content, w (%)Penetration (w)

Plastic Limit Determination

Sample no. 1 2 3




(grams)




w = Water content, w%

Plastic Limit (PL) = Average w % =

Form F




12. THE DETERMINATION OF THE PLASTIC LIMIT AND

PLASTICITY INDEX OF SOILS(METHOD A3)

SCOPEThis method covers the determination of the plastic limit of a soil as defined

hereunder by measuring the lowest moisture content at which the soil can be rolled

into threads 3 mm in diameter without the threads crumbling. It also covers the

calculation of the plasticity index from the liquid limit determined in Method A2, andthe plastic limit.

OBJECTIVE

To determine the moisture content at which a cohesive soil will change from a plastic state to a solid

state.

Definition

Plastic limi t: The plastic limit of a soil is the moisture content, expressed as a

percentage of the mass of the oven-dried soil, at the boundary between the plastic and semi-solid states.

Plastici ty index: The plasticity index of a soil is the numerical, difference between the liquid limit and

the plastic limit of the soil and indicates the magnitude of the range of the moisture contents over whichthe soil is in a plastic condition.

APPARATUS

11. Porcelain evaporating dish

12. Spatula13. Plastic squeeze bottle with water

14. Moisture can15. Glass plate measuring 150mm x 220mm

16. Oven set at 105 to 110°C.17. Balance sensitive up to 0.01g

Figures E,F,G,H – Equipment & Procedure for Plastic Limit test




Figure 12.1- Plasticity chart for classification of fine soils.

The chart is a plot of plasticity index (PI) against liquid limit (LL). The plasticity index is defined as:

PI = LL - PL

Low plasticity: LL <35%

Intermediate plasticity: LL = 35% - 50%

High plasticity: LL = 50% - 70%

Very high plasticity: LL = 70% - 90%

Extremely high plasticity: LL> 90%

A given soil may be located in its correct sub-group zone by plotting a point, having co-ordinates given by the

soils plasticity index and liquid limit.

The sub-group symbols are given below:

Fine-grained soils:

F = FINES L = low plasticity(undifferentiated) I = intermediate plasticity

M = SILT H = high plasticity

C = CLAY V = very high plasticity

E = extremely high plasticity

Organic soils:Pt = peat O = organic

TEST PROCEDURE:(1) Weigh the remaining empty moisture cans with their lids, and record the respective weights and can

numbers on the data sheet.

(2) Take the remaining 2 to 3g of the original soil sample and add distilled water until the soil is at a

consistency where it can be rolled without sticking to the hands.

(3) Form the soil into an ellipsoidal mass (See Photo F). Roll the mass between the palm or the fingers and

the glass plate (See Photo G). Use sufficient pressure to roll the mass into a thread of uniform diameter

by using about 90 strokes per minute. (A stroke is one complete motion of the hand forward and back tothe starting position.) The thread shall be deformed so that its diameter reaches 3.2 mm (1/8 in.), taking

no more than two minutes.(4) When the diameter of the thread reaches the correct diameter, break the thread into several pieces.

Knead and reform the pieces into ellipsoidal masses and re-roll them. Continue this alternate rolling,




gathering together, kneading and re-rolling until the thread crumbles under the pressure required for

rolling and can no longer be rolled into a 3.2 mm diameter thread (See Photo H).

(5) Gather the portions of the crumbled thread together and place the soil into a moisture can, then cover it.

If the can does not contain at least 6 grams of soil, add soil to the can from the next trial (See Step 6).

Immediately weigh the moisture can containing the soil, record it’s mass, remove the lid, and place the

can into the oven. Leave the moisture can in the oven for at least 16 hours.

(6) Repeat steps three, four, and five at least two more times. Determine the water content from each trial

by using the same method used in the first laboratory. Remember to use the same balance for all

weighing.

Analysis:

Plastic Limit:

(1) Calculate the water content of each of the plastic limit moisture cans after they have been in the oven for

at least 16 hours.

(2) Compute the average of the water contents to determine the plastic limit, PL. Check to see if the

difference between the water contents is greater than the acceptable range of two results (2.6 %).

(3) Calculate the plasticity index, PI=LL-PL.

Report the liquid limit, plastic limit, and plasticity index to the nearest whole number, omitting the

percent designation.

CALCULATIONS4.1 Plastic limit : The plastic limit is expressed as the moisture content in percentage of the mass of the

oven-dried soil and is calculated as follows:

The percentages are calculated and reported to the nearest whole number on the appended Form C OR

Form A2/1.

4.2 Plasticity index: The plasticity index is obtained by subtracting the plastic limit from the liquid limit,

and is determined to the first decimal figure. The plasticity index is reported with the liquid limit

(Method A2) and the linear shrinkage (Method A4) to the nearest whole number on Form A1/2 or asimilar form. If the liquid limit cannot be determined, both the liquid limit and the plasticity index are

reported as S.P. (slightly plastic) if there is slight shrinkage according to Method A4, or as N.P. (non- plastic) if there is no shrinkage at all.

5 NOTES

5.1 In the case of plastic soils, a considerable amount of kneading and rolling is required in order to reduce

the moisture content of the moist material to the plastic limit. This is time consuming, and it is therefore

suggested that the moist material from the liquid limit determination be spread out in a thin layer on thetable and left to dry out appreciably before rolling is commenced. The moisture content should not be

reduced by the admixture of dry soil.

5.2 If it is found impossible to determine the liquid limit, the determination of the plastic limit is not

attempted.




13. THE DETERMINATION OF THE LINEAR SHRINKAGE OF SOILS

(METHOD A4)

SCOPE

This method covers the determination of the linear of soil when it dried from a moisture content

equivalent to the oven-dry state.

OBJECTIVE

To determine the moisture content at which the decrease in soil volume ceases.

APPARATUS

2.1. A shrinkage trough with inside dimensions of 150 ± 0,25mm long x 10 ± 0,25 x 10 ± 0,25mm and made

of 1,6 mm thick tinned copper or stainless steel 2.2 A small thick-bristle paint brush, about 5 mm wide 2.3 A spatula with a slightly flexible blade about 100 mm long and 20 mm wide

2.4 Paraffin wax

2.5 A small enamel dish or other suitable container in which to melt the wax

2.6 A pair of dividers and a millimeter scale2.7 Oven set at 105 to 110°C

Figure 13.1 – Shrinkage Limit test procedure

TEST PROCEDURE:

The test should be run immediately after the flow curve liquid limit test (see Method A2) has been completedso that the moist material left over can be used for filling the trough without further mixing. The number of taps

required for groove closure for the final determination in the liquid limit test should be recorded, since thisvalue is required in the calculation of the linear shrinkage.




(1) A clean, dry shrinkage trough is first warmed to prevent premature setting of the wax. The inside of the

trough is then covered completely with a thin layer of molten wax applied by means of a small paint

brush. Any excess or molten wax is shaken out by tapping the trough lightly in an inverted position. The

layer of wax is now chilled by rubbing the outside of the trough with a damp cloth. This prevents the

tendency to crack on cooling, leaving the surface of the trough partly exposed. The film of wax in the

trough should weigh from 0,1 to 0,2 9 to obtain satisfactory results. Before using, the trough should be

inspected carefully, so as to ensure that there are no patches without any wax.

(2) Fill one half of the waxed trough with the moist soil by taking small pieces of soil on the spatula and

pressing the soil down against the one end of the trough and working along the trough until the wholeside is filled and the soil forms a diagonal surface from the top of one side to the bottom of the oppositeside (see Fig. (a)). The trough is now turned round and the other portion is filled in the same manner

(see Fig. (b)). The hollow along the top of the soil in the trough is now filled so that the soil is raisedslightly above the sides of the trough (see Fig. (c) ). The excess material is removed by drawing the

blade of the spatula once only from the one end of the trough to the other. The index finger is pressed

down on the blade so that the blade moves along the sides of the trough (see Fig. (d)). During this

process the wet soil may pull away from the end of the trough, in which case it should be pushed back

gently with the spatula

(3) The trough with wet material is now placed in a drying oven and dried at a temperature of between 105

and 110°C until all shrinkage has stopped. As a rule the material is dried out overnight,though three

hours should be sufficient time in the oven. The trough with material is taken out and allowed to cool inthe air.

(4) Measuring the shrinkage, it will be found that the ends of the dry soil bar have a slight lip or projecting

piece at the top. These lips must be removed by abrading with a sharp, narrow spatula, so that the end ofthe soil bar is parallel to the end of the trough (see Fig. (e) ) . If the soil bar is curved, it should be

pressed back into the trough with the finger-tips so as to make the top surface as level as possible. The

loose dust and sand, removed from the ends, as well as loose material between cracks should be emptied

out of the trough by carefully inverting the trough whilst the material is being held in position with the

fingers. The soil bar is then pressed tightly against the end of the trough. It will be noticed that the soil

bar fits better at the one end than at the other end. The bar should be pressed tightly against the end at

which there is a better fit. The distance between the other end of the soil bar and the respective end of

the trough, is measured by means of a good pair of dividers, measuring on a millimeter scale, to the

nearest 0,5 mm and recorded on Form A2/1, or similar, appended to Method A2.

CALCULATIONS

4.1 The linear shrinkage is calculated from the following formula (see 4.1):

0.8

LS = LS N x --------------

1 - 0.008Nwhere,

LS = linear shrinkage, expressed as a percentage of the original wet length of 150mm,when themoisture content is reduced from the liquid limit to an oven-dry state.

LS N = linear shrinkage, expressed as a percentage of the original wet length of 150nn,when the

when the moisture content corresponding to N taps in the liquid limit test is reduced to an oven-dry

state.

The linear shrinkage is reported to the nearest 0.5 % on Form A2/1, or a similar form.

The formula may also be written as follows:

() ()




To simplify the calculation, values of f are given in the table below for various values of N:

N f N f N f15 0.61 22 0.65 29 0.70

16 0.61 23 0.65 30 0.70

17 0.62 24 0.66 31 0.71

18 0.62 25 0.67 32 0.72

19 0.63 26 0.67 33 0.73

20 0.64 27 0.68 34 0.73

21 0.64 28 0.69 35 0.74

NOTES

1. For a soil paste with a moisture content requiring between 15 and 35 taps for groove closure in the liquid

limit test, a linear relationship has been found to exist between the number of taps (N) and the shrinkage of

the soil paste when dried. Different soil types give different straight line curves and there is a tendency for

these lines to converge at about N = 125 when the shrinkage = 0. For this family of straight lines, the

relationship between the linear shrinkage from a moisture content equivalent to the liquid limit and the

linear shrinkage from a moisture content corresponding to N taps in the liquid limit test, is as given by the

formula.

2. The troughs should be examined for dents and distorted sides, and any faults corrected before use.

3. After testing, the soil bar should be examined to ensure that the corners of the trough were filled properlyand that no air pockets were contained in the soil bar.




14. THE DETERMINATION OF THE GRAIN SIZE DISTRIBUTION IN SOILS BY

MEANS OF A HYDROMETER (Method A6)

SCOPE

This method covers the quantitative determination of the distribution of the of particle sizes in soils by

means of a sedimentation process, based on Stokes’ Law, by using a specially calibrated hydrometer.

OBJECTIVE To introduce the student to the methods of making a mechanical and hydrometer grain-size analysis of

a soil and to present the resulting data.

APPARATUS

A balance, accurate to 0.1g

A canning jar, wide mouth, about 1000ml capacity

A bouyoucos cylinder

A bouyoucos hydrometer

A dispersing apparatus with paddles

A stop watch A thermometer

Sodium hexametaphosphate

Figure 14.1 - Equipment for Hydrometer test

TEST PROCEDURE

1.) Weigh out 100g of the soils fines (< 0,425mm).

2.) Add 400ml of distilled water as well as 40g sodium hexametaphosphate stirred well and let to stand for2 hours.




3.) Mix contents thoroughly with dispersing apparatus for 15minutes, and pour the total suspension into the

Bouyoucos cylinder.

4.) Fill the cylinder with distilled water to the 1205ml mark with the hydrometer inside.

5.) Remove hydrometer and place the cylinder in a constant temperature bath at 20 °C.

6.) Shake the cylinder end over end until a homogenous suspension is obtained. Returned the cylinder to

the water bath and start stop watch.

7.) After 1 hour the hydrometer is inserted and a reading is taken and the temperature, using a thermometer.

8.) Then a 40 second reading is taken along with temperature

9.) Then an 18 second reading is taken along with temperature

CALCULATIONS

Stokes’s Law:

Stokes’s law states that: Maximum grain diameter

√ ( )

Where,

n = viscosity of the suspending medium in Pascal-seconds. The viscosity of distilled water at

20 0C is 0.001005 Pa.s

L = the distance in centimeters through which the grains settle in a period of time, T

T = time in minutes, period of sedimentation.G = relative density of soil particles

G1 = relative density of suspending medium (which is 0.99823for water at 20 °C)

1. The following table gives the maximum diameter of the particles which are accounted for by thehydrometer after different time intervals (see 5.6).

2. The following corrections should be applied to the hydrometer readings:

Hydrometer Readings

at

Maximum diameter of

particles in mm’s Common term

18 seconds 0.075 Material passing the 0.075 sieve

40 seconds 0.05 Silt & Clay

1 hour 0.005 Clay

3. If the temperature of the suspension at the time of the hydrometer reading is not 20 °C, a correction

should be made to the reading in accordance with the following table:

4. If a 50 gram sample is used, the readings must be doubled after the correction for temperature has been

made. The rest of the calculations are then the same as set out below.5. The material smaller than 0,075mm (18-second reading) is always expressed as a percentage of the total

sample. The material smaller than 0,05 mm is expressed as a percentage of the total sample and also as a

percentage of the soil mortar (i.e. the traction passing the 2,0mm sieve). The material smaller than 0,005

mm is only expressed as a percentage of the soil mortar.

6. The soil mortar is divided into four fractions viz.:

a. Coarse sand: passing 2,0 and retained on 0,425 mm sieve

b. Fine sand: passing 0,425 mm and retained on 0,05 mm sieve

c. Silt: passing 0,05 and retained on 0,005 mm sieve

d. Clay: passing 0,005 mm sieve




These fractions are expressed as percentages of the soil mortar and are calculated as follows:

a. Coarse sand

Where,

P1 = percentage coarse sand in the soil mortar

Sm = percentage soil mortar in total sample (determined in Method A1 (a) or A1 (b))

Sf = percentage soil fines in total sample (determined in Method A1 (a) or A1 (b))

b. Fine sandThe percentage fine sand in the soil fines is obtained by subtracting the reading obtained with the

hydrometer at 40seconds from 100 (the mass of soil fines used for hydrometer analysis). The percentage

of tine sand in the soil mortar can thus be calculated as follows:

()

Where,

P2 = percentage of fine sand in soil mortar

F = 40-second hydrometer reading

c. SiltThe percentage of silt in the soil fines is obtained by subtracting the one-hour hydrometer reading trom

the 40-second reading and the percentage of silt in the soil mortar can then be calculated as follows:

( )

Where,P

3 = percentage silt in the soil mortar

C = one-hour hydrometer reading

d. ClayThe percentage of clay in the soil mortar can be calculated from:

Where,

P4 = percentage of clay in the soil mortar

7. Percentage of silt plus clay in the total sample

This can be calculated from:

Where,P

5 = percentage silt plus clay in total sample

8. Percentage passing the 0,075mm sieve in the total sample

This can be calculated from:

Where

P6 = percentage smaller than 0,075 mmE = 18-second hydrometer reading




The calculations should be done to the nearest 0,1 and the percentage passing the 0,075 mm sieve and

the soil mortar analysis reported on the Hydrometer Analysis data sheet.

Hydrometer Analysis:(1) Apply meniscus correction to the actual hydrometer reading.

(2) From Table 1, obtain the effective hydrometer depth L in cm (for meniscus corrected reading).

(3) For known Gs of the soil (if not known, assume 2.65 for this lab purpose), obtain the value of K from

Table 2.

(4) Calculate the equivalent particle diameter by using the following formula:

√

Where t is in minutes, and D is given in mm.

(5) Determine the temperature correction C T from Table 3.(6) Determine correction factor “a” from Table 4 using Gs.

(7) Calculate corrected hydrometer reading as follows:




Table 1. Values of Effective Depth Based on Hydrometer and Sedimentation Cylinder of Specific Sizes

Hydrometer 151H Hydrometer 152H

Actual

HydrometerReading

EffectiveDepth, L (cm)

Actual

HydrometerReading

Effective Depth,L (cm)

Actual

HydrometerReading

Effective Depth,L (cm)

1.000 16.3 0 16.3 31 11.2

1.001 16.0 1 16.1 32 11.1

1.002 15.8 2 16.0 33 10.9

1.003 15.5 3 15.8 34 107

1.004 15.2 4 15.6 35 10.6

1.005 15.0 5 15.5 36 10.4

1.006 14.7 6 15.3 37 10.2

1.007 14.4 7 15.2 38 10.1

1.008 14.2 8 15.0 39 9.9

1.009 13.9 9 14.8 40 9.7

1.010 13.7 10 14.7 41 9.6

1.011 13.4 11 14.5 42 9.4

1.012 13.1 12 14.3 43 9.2

1.013 12.9 13 14.2 44 9.1

1.014 12.6 14 14.0 45 8.91.015 12.3 15 13.8 46 8.8

1.016 12.1 16 13.7 47 8.6

1.017 11.8 17 13.5 48 8.4

1.018 11.5 18 13.3 49 8.3

1.019 11.3 19 13.2 50 8.1

1.020 11.0 20 13.0 51 7.9

1.021 10.7 21 12.9 52 7.8

1.022 10.5 22 12.7 53 7.6

1.023 10.2 23 12.5 54 7.4

1.024 10.0 24 12.4 55 7.3

1.025 9.7 25 12.2 56 7.11.026 9.4 26 12.0 57 7.0

1.027 9.2 27 11.9 58 6.8

1.028 8.9 28 11.7 59 6.6

1.029 8.6 29 11.5 60 6.5

1.030 8.4 30 11.4

1.031 8.1

1.032 7.8

1.033 7.6

1.034 7.3

1.035 7.0

1.036 6.8

1.037 6.5

1.038 6.2

1.039 5.9




Table 2. Values of k for Use in Equation for Computing Diameter of Particle in Hydrometer Analysis

Temperature

°CSpecific Gravity of Soil Particles

2.45 2.50 2.55 2.60 2.65 2.70 2.75 2.80 2.85

16 0.01510 0.01505 0.01481 0.01457 0.01435 0.01414 0.0394 0.01374 0.01356

17 0.01511 0.01486 0.01462 0.01439 0.01417 0.01396 0.01376 0.01356 0.01338

18 0.01492 0.01467 0.01443 0.01421 0.01399 0.01378 0.01359 0.01339 0.01321

19 0.01474 0.01449 0.01425 0.01403 0.01382 0.01361 0.01342 0.01323 0.01305

20 0.01456 0.01431 0.01408 0.01386 0.01365 0.01344 0.01325 0.01307 0.01289

21 0.01438 0.01414 0.01391 0.01369 0.01348 0.01328 0.01309 0.01291 0.01273

22 0.01421 0.01397 0.01374 0.01353 0.01332 0.01312 0.01294 0.01276 0.01258

23 0.01404 0.01381 0.01358 0.01337 0.01317 0.01297 0.01279 0.01261 0.01243

24 0.01388 0.01365 0.01342 0.01321 0.01301 0.01282 0.01264 0.01246 0.01229

25 0.01372 0.01349 0.01327 0.01306 0.01286 0.01267 0.01249 0.01232 0.01215

26 0.01357 0.01334 0.01312 0.01291 0.01272 0.01253 0.01235 0.01218 0.01201

27 0.01342 0.01319 0.01297 0.01277 0.01258 0.01239 0.01221 0.01204 0.0118828 0.01327 0.01304 0.01283 0.01264 0.01244 0.01255 0.01208 0.01191 0.01175

29 0.01312 0.01290 0.01269 0.01269 0.01230 0.01212 0.01195 0.01178 0.01162

30 0.01298 0.01276 0.01256 0.01236 0.01217 0.01199 0.01182 0.01165 0.01149

Table 3. Temperature Correction Factors CT Table 4. Correction Factors a for Unit

Weight of Solids

Temperature

°Cfactor CT

Unit Weight of Soil

Solids, g/cm3

Correction factor

a

15 1.10 2.85 0.96

16 -0.90 2.80 0.97

17 -0.70 2.75 0.98

18 -0.50 2.70 0.99

19 -0.30 2.65 1.0

20 0.00 2.60 1.01

21 +0.20 2.55 1.02

22 +0.40 2.50 1.04

23 +0.70

24 +1.00

25 +1.30

26 +1.65

27 +2.0028 +2.50

29 +3.05

30 +3.80

Questions1. What do the results mean?

2. How can the soil be classified?

3. What were the sources of error?4. What could be done to reduce the error?




HYDROMETER ANALYSIS DATA SHEET

General Information:

Lab Partners: Sample No.:

Specific Gravity (GS): Dry weight of Specimen(g):

Temperature (°C) Hydrometer type: 152 - H

Meniscus Correction: Zero Correction:K factor GS correction factor:

Temp correction factor:

Test Data:

Time Hydrometer Adj. Hydrometer Effective Percent D

Reading Reading Depth, L (cm) Finer (mm)

18 sec

40 sec

1 hour




15. METHOD OF TEST FOR SPECIFIC GRAVITY OF SOILS

SCOPE

This method of test, which is a modification of emission of air and surplus water. AASHTO Designation T100, is used for the determination of the specific gravity of soils by means of a pycnometer.

INTRODUCTION

The specific gravity of a material is defined as the ratio of the mass of a unit volume of a material to the

mass density of gas-free distilled water at a stated temperature. Specific gravity of soil solids is written as

where and are the mass density, mass per unit volume, of the soil solids and water, respectively. A

material with a specific gravity greater than water is denser than water so it will not float in water.

Specific gravity is used in computations involving phase relationships that are expressed in terms of unit

weight, where unit weight is defined as the weight of material per unit volume. The specific gravity of soil

solids falls within the following ranges of values.

Soil Type Range of Gs Sand 2.63 – 2.67

Silty Sand 2.67 – 2.70Silts 2.65 – 2.70

Silty Clay 2.67 – 2.80Clay 2.70 – 2.80

Organic Soil 1+ to 2.60

APPARATUS1. Pycnometer. One of the following:

a. Volumetric flask having a capacity of 500 ml.

b. Volumetric flask having a capacity of 100 ml.

c. A stoppered bottle having a capacity of 50ml. The bottle stopper shall be of the same material as the

bottle, and shall be capable of being easily inserted to a fixed depth in the neck of the bottle, andshall have a small hole through its center to permit the emission of air and surplus water.

The use of either the volumetric flasks or the stoppered bottle is a matter of individual preference,

but in general, a flask should be used when a larger sample than can be used in the stoppered bottle

is needed due to maximum grain size of the sample.

2. Balance: Either a balance sensitive to 0.01 g for use with the 100 ml and 500 ml volumetric flasks, or a

balance sensitive to 0.001 g for use with the 50 ml stoppered bottle.

3. Thermometer sensitive to 1°C.

Figure 15.1 – Specific Gravity apparatus




CONTROL

The temperatures of the pycnometer contents at the two weighings shall be 20 ± 5°C, and these

temperatures designated at T i and T x shall not differ by more than 5°C.

Alternate: If it is desired to perform the test at temperatures outside the above specified range, corrections

for differences in temperature shall be applied as provided in AASHTO Designation T 100.

CALIBRATION OF PYCNOMETER

Clean and dry the pycnometer, then determine and record its mass in grams. Fill the pycnometer with distilledwater having a temperature of 20 ± 5°C. Determine and record the mass in grams, Wa, of the pycnometer andwater. Insert the thermometer in the water and read and record the temperature, T i, to the nearest whole degree

Celsius.

SAMPLE PREPARATION

1. The soil to be used in the specific gravity test may contain its natural moisture or be oven-dried. The

mass of the test sample on an oven-dry basis shall be at least 125 g when the 500 ml flask is to be used,

at least 25 g when the 100 ml flask is to be used, and at least 10 g when the 50 ml stoppered bottle is to

be used.

2. Samples containing natural moisture:

a. When the sample contains its natural moisture, determine the mass of the soil, Wo, on an oven-dry basis at the end of the test by evaporating the water from the sample in an oven maintained at

110°C. Drying of certain soils at 110°C may bring about loss of moisture of composition or

hydration, and in such cases, drying shall be done, if desired, in reduced air pressure and at a lower

temperature.

b. Disperse samples of clay soils containing their natural moisture content in distilled water before placing in the flask, using the mechanically operated stirring apparatus specified in the Standard

Method of Mechanical Analysis, AASHTO Designation T- 88.

3. Oven-dried samples: When an oven-dried sample is to be used, dry the sample for at least 12 hours, or

to constant mass, in an oven maintained at 110°C. However, a lower temperature may be permitted forcertain soils as explained in 2a above. Cool the sample in a desiccator and determine the mass upon

removal from the desiccator. Then soak the sample for at least 12 hours in distilled water.

TEST PROCEDURE1. Place the test sample in the pycnometer, taking care not to lose any of the soil in case the oven-dry mass

has been determined. Add distilled water to the flask until it is about three-fourths full or to thestoppered bottle until it is about half full.

2. Remove entrapped air by either of the following methods:

a. Subject the contents to a partial vacuum (air pressure not exceeding 100 mm of mercury).

b. Gently boil the contents for at least 10 minutes while occasionally rolling the pycnometer to assist in

the removal of air.

3. Subjection of the contents to reduced air pressure may be done either by connecting the pycnometer

directly to an aspirator or vacuum pump, or by use of a bell jar. Some soils boil violently when

subjected to reduced air pressure. It will be necessary in those cases to reduce the air pressure at a

slower rate or to use a larger flask. Samples that are heated shall be cooled to approximately 20°C.

4. After the air has been removed, fill the pycnometer with distilled water and bring the temperature of the

total contents to 20 ± 5°C and within 5°C of temperature Ti by use of a water bath or other suitable

means. Clean and dry the outside of the pycnometer with a clean, dry cloth. Determine and record the

mass in grams of the pycnometer and contents, W b, and the temperature in degrees Celsius, T x, of the

contents.

5. If the test was performed on a test sample which contained its natural moisture, determine the dry massof the material by evaporating off the water in an oven maintained at 110°C, or at a lower temperature




as explained under E-2, until the material reaches a constant mass. Cool the sample to room

temperature, determine the mass in grams and record the mass, W o.

CALCULATIONS1. Calculate the specific gravity of the soil as follows:

( )

Where:

G s = Specific gravityW o = Mass in grams of sample of oven dry soil

W a = Mass in grams of pycnometer filled with water at temperature T iWb = Mass in grams of pycnometer filled with water and soil at temperature T x

EXAMPLE DATA

SPECIFIC GRAVITY DETERMINATION

DATA SHEET

Date Tested: March 15, 2010

Tested By: S3, Group 1 Project Name: Geotechnical Engineering II

Lab Sample Number: G-1 Sample Description: Gray silty clay

Specimen number 1 2

Pycnometer bottle number 96 37

W p = Mass of empty, clean pycnometer (grams) 37.40 54.51W ps = Mass of empty pycnometer + dry soil (grams) 63.49 74.07

W b = Mass of pycnometer + dry soil + water (grams) 153.61 165.76

Wa = Mass of pycnometer + water (grams) 137.37 153.70

Specific gravity (Gs) 2.65 2.61

Example Calculation: W p = 37.40 g, W ps = 63.49 g, W b = 153.61 g,

W a =137.37 gW o = 63.49 – 37.40 = 26.09 g

( )

(()




SPECIFIC GRAVITY DETERMINATION

DATA SHEET

Date Tested:

Tested By:

Project Name:

Sample Number:

Sample Description:

Specimen number 1 2

Pycnometer bottle number

WP = Mass of empty, clean pycnometer (grams)

WPS = Mass of empty pycnometer + dry soil (grams)

WB = Mass of pycnometer + dry soil + water (grams)

WA = Mass of pycnometer + water (grams)

Specific Gravity (GS)

Calculations:




16. The AASHTO Classification System

AASHTO Classification Chart

General Classification Granular Materials (35% or less passing the 0.075 mm sieve)Silt-Clay Materials (>35% passing the 0.075

mm sieve)

Group ClassificationA-1

A-3A-2

A-4 A-5 A-6A-7

A-1-a A-1-b A-2-4 A-2-5 A-2-6 A-2-7 A-7-5 A-7-6

Sieve Analysis, % passing

2.00 mm (No. 10) 50 max … … … … … … … … … …

0.425 (No. 40) 30 max 50 max 51 min … … … … … … … …

0.075 (No. 200) 15 max 25 max 10 max 35 max 35 max 35 max 35 max 36 min 36 min 36 min 36 min

Characteristics of fraction passing 0.425

mm (No. 40)

Liquid Limit … … 40 max 41 min 40 max 41 min 40 max 41 min 40 max 41 min

Plasticity Index 6 max N.P. 10 max 10 max 11 min 11 min 10 max 10 max 11 min 11 min1

Usual types of significant constituent

materials

stone fragments, gravel

and sand

fine

sandsilty or clayey gravel and sand silty soils clayey soils

General rating as a subgrade excellent to good fair to poor

Note: Plasticity index of A-7-5 subgroup is equal to or less than the LL - 30. Plasticity index of A-7-6 subgroup is greater than LL – 30

Using the above table of the laboratory manual, the idea is to classify a soil as high as is possible based on the GSD and the Atterberg limits.

Once an AASHTO Group Classification has been found, a so-called “group index” (GI) can be determined to further classify soils within a given group.

For soils in AASHTO group A-3 or lower: ( )[( )] ( )( )

For soils in A-1 or A-2:( )( )

In both formulas, F is the percent of the soil sample passing the #200 (0.075mm) sieve.

http://www.aboutcivil.com/atterberg-limits.html


http://en.wikipedia.org/wiki/AASHTO_Soil_Classification_System#fn_1







Example #1: Classify the following soil by the AASTHO System.

Given:

% passing No. 10 (2.00mm) sieve = 100



LL = 30

PI = 10

Solution:From Table 4.1, the group classification is A-4.

From the given data, F = 58 ( )[( )] ( )( ) ( )[( )] ( )( ) ()[()] ()() 3.45

Thus, the AASHTO Classification is A-4 (3)

Example #2: Classify the following soil by the AASTHO System.

Given:


LL = 60

PI = 40

Solution:

From Table 4.1, the group classification is A-4.

From the given data, F = 95

( )[( )] ( )( ) ( )[( )] ( )( ) ()[()] ()() 42

Thus, the AASHTO Classification is A-7-6 (42)




16.1 The Unified Classification System (UCS)




16.2 Unified Soil Classification procedures




17 The Unified Classification System (UCS)

Required Information:

% of sample that is gravel : 4.75mm ≤ d ≤ 75mm

% of sample that is sand : 0.075mm ≤ d ≤ 4.75mm

% of sample that is silt & clay : 0.075mm ≤ d ≤ 0.075mm

Uniformity coefficient :

Coefficient of gradation : ()[]

LL and PI on portion passing No. 40 (0.425mm) sieve

The Unified Classification System (UCS) procedure:

Step (1): Determine F200 (% finer than No. 200 (0.075mm) sieve)

If F200 < 50% →→ Step (2) If F200 ≤ 50% →→ Step (3)

Step (2): Coarse Fraction is

F1 is the % passing No. 4 (4.75mm) sieve, but retained on No. 200 (0.075mm) sieve (i.e sand)

If F1 <() , then the coarse fraction is more gravel than sand.

Go to Table above (identification & description)

If F1 >() , then the coarse fraction is more sand than gravel.

Go to Table above (identification & description)

Step (3): Fine-grained soils.Go to Table above (identification & description)




Example #1: Classify the following soil using Unified Soil Classification System.

Given:

gravel fraction (% retained on No. 4 (4.75mm) sieve = 30%

sand fraction (passing No. 4 (4.75mm) sieve, retained on No. 200 (0.075mm) sieve = 40%

silt and clay fraction (passing No. 200 (0.075mm) sieve = 30%

LL = 30

PI = 12

Solution:

, therefore go to Step (2).

and()

Since F1 >() , coarse fraction is more sandy than gravelly →→ Table above (identification &

description).

From Table above (identification & description):

Group symbol is SC

From Table above (identification & descr iption), group name is “Clayey sand with gravel”

Example #2: Classify the following soil using Unified Soil Classification System.

Given:

gravel fraction (% retained on No. 4 (4.75mm) sieve = 0%

sand fraction (passing No. 4 (4.75mm) sieve, retained on No. 200 (0.075mm) sieve = 14%

silt and clay fraction (passing No. 200 (0.075mm) sieve = 86%

LL = 55

PI = 28

Solution:

, therefore go to Step (3). From Table above (identification & description):

Group symbol is CH Inorganic Clay

From Table above (identification & description), group name is “Fat Clay”




18. MAXIMUM DRY DENSITY AND OPTIMUM MOISTURE

CONTENT(MODDS) TEST (Method A7)

OBJECTIVE

To determine the maximum dry unit weight of compaction of soils which can be used for specification

of field compaction.

APPARATUS1. Compaction mould, collar & base plate

2. Standard Proctor hammer(4.536kg)

3. Riffler,19mm

4. Sieves,19mm and 4.75mm

5. Balance sensitive up to 0.1g (2kg)

6. Balance sensitive up to 5g (15kg)

7. A large pan

8. A jack

9. A Steel straight edge

10. Steel tamper

11. An iron mortar and pestle and a rubber - t ipped pestle12. Basins, 350mm & 500mm in diameter

13. Moisture cans14. Measuring cylinders,1000ml

15. Oven16. Garden trowel

17. Plastic squeeze bottle

18. Spatula

19. Filter paper




PROCEDURE1. Collect apparatus- steel mould, collar and base plate, mixing basin, filter paper, tamper and dropper, moisture content

container for ovens, sample extruder, steel straight edge, sieves (19mm and 4.75mm), riffler with pans, measuring cylinder2. Work in Groups of 4 students per group. You will be given a % MC to work with

3. Measure +/- 7 kg soil sample4. Sieve through a 19mm sieve5. Crush material which is left behind with the steel tamper until it can pass thro sieve

6. Add to other material7. Measure and record the exact mass of your air-dry material8. Determine the volume of water to add to this based on your %MC (given)

9. Record the volume and mass of the mould10. Add water to air-dry material and mix11. Assemble mould with collar and base plate, placing filter paper at bottom12. Place about 1kg of material into the mould, level and apply 55 blows with tamper as instructed (5 cycles of 11 blows each to

the layer)13. Measure the depth of this material to mould collar (should be 96-99 mm)14. Add successive layers of 25-30mm each, apply 55 blows to each layer added

15. Weigh around 500g of the mixed soil sample after placing the 2nd

layer16. Place this into an oven bowl for oven drying at a later stage after the sample has been fully compacted17. Once the last layer is placed and compacted, the collar is removed18. Level the material and tap into mould with the straight edge

19. Fill any holes in the material with loose material passing through the 4.75mm sieve20. Remove and weigh the mould and material- record this

21. Extrude the sample from the mould22. Place oven sample into oven overnight at 105-110ºC23. Record the oven dried weights the next day24. Do calculations

REPORT AND CALCULATIONSCalculate the Actual Moisture Content (MC %) of each sample-

MC = (a-b)/(b-c) x 100Where: MC = the actual moisture content (as a percentage of the air-dried soil)

a = Mass of the container plus wet material (g) b = Mass of container plus dry material (g)

c= Mass of container only

Calculate the Dry Density (DD kg/m3) of each sample-DD = [ (M2 – M1) / (MC+100) ] x 100/V x 1000

Where: DD = Dry density of soil sample (kg/m3)

MC = the actual moisture content (as a percentage of the air-dried soil)M1 = Mass of the mould (g)

M2 = Mass of the mould plus wet material (g)V = Volume of the mould (ml)

The Graph of MC vs DD- (EXAMPLE)

Figure 18.1 – Example of moisture – density relationship curve




Figure A,B,C,D,E,F,G,H,I – MODDS Equipment & Procedure




MODDS MOULD CALIBRATIONS

Mould &

Group NoMass(g) Volume(g/ml) Factor(100/V) x 1000

Gr. 1 A 4773 2311 43.271

B 4770 2277 43.917

C 4769 2300 43.478

Gr. 2 A 4878 2324 43.029

B 4734 2327 42.974

C 4682 3299 30.312

Gr. 3 A 4819 2343 42.68

B 4685 2295 43.573

C 4570 2312 43.253

Gr. 4 A 4653 2283 43.802

B 4802 2388 41.876

C 4883 2287 43.725

Gr. 5 A 4994 2259 44.267

B 4820 2309 43.309

C 4744 2277 43.917

Gr. 6 A 4705 2221 45.025

B 4848 2251 44.425

C 4824 2298 45.29

Gr. 7 A 4869 2312 43.253

B 4819 2311 43.271

C 4895 2216 45.126

Gr. 8 A 4902 2311 43.271

B 4872 2391 41.824

C 5031 2449 40.833

Gr. 9 A 4861 2283 43.802

B 4789 2256 44.326

C 4715 2242 44.603

Gr10 A 4859 2278 43.898

B 4739 2301 43.459

C 4787 2303 43.422




FORM E – M.D.D. graph sheets




19. CALIFORNIA BEARING RATIO OF UNTREATED SOILS AND

GRAVEL TEST (CBR) OR (Modified Proctor Compaction Test)

(Method A8)

OBJECTIVE

To determine the load required to allow a standard piston to penetrate the surface of a compacted

material.

SCOPE

The California Bearing Ratio (CBR) of a material as defined below, is determined by measuring the

load required to allow a standard piston to penetrate the surface of a material compacted according to

Method A7. The determination of the CBR-density relationship and swell of the material is also

covered.

APPARATUS

1. Compaction mould, collar & base plate

2. Perforated soaking base plates



5. Annular surcharge weights(4.536kg) with adjustable stems6. A swell tripod fitted with two dial gauges

7. Riffler,19mm8. Sieves,19mm and 4.75mm

9. Balance sensitive up to 0.1g (2kg)10. Balance sensitive up to 5g (15kg)

11. Large pans,1000g

12. A jack

13. A Steel straight edge

14. Steel tamper15. An iron mortar and pestle and a rubber - t ipped pestle

16. Basins, 350mm & 500mm in diameter

17. Measuring cylinders,1000ml

18. Oven

19. Garden trowel

20. Plastic squeeze bottle

21. Spatula

22. Filter paper

23. A compression testing machine24. A stop watch

25. A soaking bath




Figure 19.1 – General arrangement for CBR test

METHOD

Preparation

The material is prepared as set out in Method A7, i.e. all aggregate retained on the 19,0mm sieve is

crushed lightly to pass that sieve, and if the sample contains soil aggregations, these should be

disintegrated. Approximately 25 kg of the thoroughly mixed material is now divided out. I n order to

ensure that the material used for this test is exactly similar to that used for the determination of the

moisture-density relationship, the preparation and division for the two tests are carried out at the sametime as one operation.

Determination of hygroscopic moisture content

Two representative samples are taken and placed in suitable containers to determine the moisture

content. The samples should be between 500 and 1 000 9. The more coarsely graded the material, the

larger the samples. The samples are weighed immediately and dried to constant mass in an oven at

105oC to 110

oC. The average moisture content is determined to the nearest 0,1 per cent. Immediately

after the moisture content samples have been taken, the material is transferred to an air-tight container

Admixture of water

The moulding moisture content should be the optimum moisture content (± 0,3 per cent) as determined

in accordance with Method A7. Therefore, the additional water to be admixed is the difference between




the optimum and the hygroscopic moisture content. After the latter has been determined the material in

the airtight tin is weighed and transferred to the mixing bath. The required amount of water is

calculated, measured out and added slowly by means of the spray can or sprinklers. While adding the

water, the material should be mixed continuously with a trowel. The moist material is now covered with

a damp sack to prevent evaporation and allowed to stand for at least half an hour so that the moisture

may become evenly distributed throughout. After a quick remix, a representative sample is taken for the

determination of the moisture content and the moist material is then again transferred to the airtight tin,

where it remains until the result of the moisture determination is available, usually overnight. If the

moisture content is more than 0,3 per cent above the optimum moisture content, the whole sample isremixed in the bath, allowing the moist material to dry slightly by evaporation. The operator will have

to use his discretion as to how long the material should be mixed. If the moisture content is more than

0,3 per cent below the optimum moisture content, the calculated additional water is admixed. After

either of these adjustments has been made, another moisture content is determined, the moist material in

the air-tight tin again being stored until the result is available. No further adjustment ought to be

necessary if the operator is reasonably experienced.

N.B. - The mixing of the wet material in order to ensure that it is homogenous and atthe right moisture

content is most important. When mixing, the moist material should be kept loose and on no account

should the clayey soil fines be allowed to form clods. Care should also be exercised to ensu re that

representative samples are taken for moisture content determinations.

Preparation of moulds

The volumes of three moulds are determined as set out in Method A7, Section 5.3. The clean dry

moulds are then weighed and one is assembled ready for tamping. Two 150 mm rounds of filter paper

are placed on the spacer plate and the collar is fitted to the mould.

Compaction

The moist material (at the specified moisture content) is transferred from the tin to the mixing bath. It isthoroughly but rapidly mixed and then covered with a damp sack, which should be kept over the

material until the compaction is completed so as to keep the moisture content as constant as possible.The first mould is now tamped full of material, the excess material removed and only the mould with

the material weighed, as described in Method A7. A representative sample for moisture content is now

taken from the mixing bath. The second mould is then assembled immediately and tamped full ofmaterial in a similar manner, except that only 25 blows of the 4,536 kg tamper are applied to each layer.

It is probable that for each layer to be compacted, less material will have to be weighed off than in thecase of the higher compactive effort. The moulded material is finished off and weighed and another

representative sample for moisture content is taken from the mixing bath. The third mould is then

prepared and tamped full of material, but in th is case only three layers of material are compacted and on

each layer 55 blows of the 2,495 kg tamper are applied. As with the other compactive efforts, between 5

mm to 15 mm of material should project above the top of the mould, and hence, each layer should be

approximately 46 mm in thickness. The moulded material is again finished off and weighed.

The compactive efforts used for the three moulds are summarized as follows:

(a) 4,536 kg tamper, 457,2 mm drop, five layers and 55 blows per layer.

(b) 4,536 kg tamper, 457,2 mm drop, five layers and 25 blows per layer.

(c) 2,495 kg tamper, 304,8 mm drop, three layers and 55 blows per layer.

The average of the two moisture content determinations, taken after the compaction of the first and

second moulds, is taken as the moulding moisture content for all three moulds.

SoakingThree perforated soaking base plates are placed ready with a wire gauze disc over the perforations and a

150 mm round of filter paper on top of the gauze. Each mould is then placed on the filter paper with the




finished off surface facing downwards and screwed down tightly onto the soaking plate. The surface of

the moulded material which was against the spacer plate, and on which there is a round of filter paper,

should be facing upwards. A perforated plate with adjustable stern is then placed on top of the filter

paper on the surface of the material and a 4,536 kg surcharge weight is placed carefully on top of the

plate. The whole assembly is then transferred to an empty soaking bath. The tripod with the dial gauge

is then placed on the mould with the rear leg on a mark on the rim of the mould so that the same

position is used for subsequent readings of the swell. The stem of the perforated plate is adjusted so that

the dial gauge reads 1 mm. After removal of the tripod and dial gauge, the bath is filled with water to a

depth of about 12 mm above the top of the mould. To ensure that the water has free access to the bottomof the material in the mould, suitable strips are fitted to the bottom of the bath, or, alternatively, a layerof small stone chippings is placed in the bath. The mould with material is allowed to soak for four days,

and readings with the dial gauge should, if possible, be taken each day.

Draining after soaking

After four days' soaking, the mould, with perforated plate, etc., is removed from the water. The water

is poured out by holding the mould in a slanting downward position and holding the perforated plate

and soaking weight in position. It is held like this for about one minute and then returned to its normal

position and allowed to drain for 15 minutes on a grid or on a layer of chippings. The perforated plate

with stem and the soaking weight are removed carefully.

N.B. - In all handling of the moulded material care should be exercised not to jar thematerial.

PenetrationThe mould with material, still screwed down on the soaking plate, is placed in the press and the 5,56 kg

surcharge weight is placed carefully on top of the material as centrally as possible. The penetration

piston is seated on the surface of the material through the centre of the annular weight. The depth gauge

is fitted in such a manner that the depth of penetration of the piston into the material can be measured.

The speed of penetration is determined by means of the stop-watch and it is, therefore, desirable to have

it mounted adjacent to the dial gauge, with the two zeros at the top of the dials. After setting the depth

gauge to zero, the load is applied at a uniform rate of penetration of 1,27 mm per minute. Load readings

are taken every 0,635 mm penetration as recorded on the depth gauge. The piston is allowed to penetrate

9,0 mm or slightly more. Having a depth gauge registering 1,27 mm per revolution, and a stop-watch

with a 60-second dial, means that the hands of the gauge and the stop-watch should move roundtogether.

CALCULATIONS

Moisture Content (%)The hygroscopic moisture content, the check moisture contents after admixing of water and the

moulding moisture content are calculated as set out in Method A7.

a) Amount of water to be admixed

( )

where

W = amount of water to be admixed

x = hygroscopic moisture content.

y = required (optimum) moisture content.

z = mass of air-dried test sample.

b) Dry density of moulded material (kg/m3)

Using the moulding moisture content, the dry density of the moulded material is calculated as set out in

Method A7.




c) Swell (%)

( )

where

S = swell expressed as a percentage of the height of the moulded material before soaking, i.e. 127mm

k = dial gauge reading after four days' soaking

L = dial gauge reading before soaking

The swell is reported to the nearest first decimal point on the A8/1 or similar form

California Bearing Ratio

For each specimen the stress-strain curve is drawn on a natural scale, i.e. the load readings are plottedagainst the depth of penetration (see appended example, Figure A8/l). In some cases the curve will have

a concave downward shape, varying from an almost straight line relationship to a curve in which therate of increase in the load readings decreases with the depth of penetration. However, many curves in

the initial stages have a concave upwards shape, and in order to obtain true stress-strain relationships,such curves should be corrected by extending the straight line portion of the curve downwards until it

intersects the abscissa. The point of intersection is then taken as the zero depth of penetration.

Using this new zero, the load is read off at 2,54 mm; 5,08 mm and 7,62 mm penetration. The readingsfor the above depths of penetration are then expressed as a percentage of the California standard for that

penetration, viz.

Penetration California Standard

Millimetres kNewtons

2.54 13.344

5.08 20.016

7.62 25.354

This percentage is called the California Bearing Ratio (CBR) at the particular depth of penetration. The

CBR at 2,54 mm penetration is generally used for assessing the quality of materials. All calculations

should be carried out to the first decimal figure except for the quantity of water to be added which is

calculated to the nearest gram or ml.

CBR-Density Relationship

In order to obtain the relationship between CBR and dry density, the CBR at 2,54 mm penetration is

plotted on a logarithmic scale against the dry density on a natural scale for the three compactive efforts

used, on Form A8/4. The best fit line of the three points is an isoline of moulding moisture content, i.e.the moisture content is the same for the three points. The design CBR can thus be obtained at the desired

percentage of the maximum dry density--normally the specified minimum percentage compaction. The

results are recorded on the A8/2 or similar Form.

NOTES

The 0,01 mm gauge may be used to measure the depth of penetration and the 0,127 mm gauge to control therate of penetration, as described in 3.8. As an alternative, the 0,127 mm gauge may also be used to measure the

depth of penetration and load readings may be taken every 0,635 mm penetration, i.e. at the 'bottom' and 'top'

position of the gauge.

In view of the fact that the optimum moisture content has to be determined (Method A7) before the CBR testcan be carried out, the first part of the procedure can be adapted as follows:




Preparation - After a sufficiently large sample for the moisture-density and CBR test has been prepared to pass

the 19,0 mm sieve, the material is moistened to about three per cent below optimum moisture content and

mixed thoroughly. The whole sample is then transferred to air-tight tins and stored at least overnight. This will

allow the moisture to become evenly distributed which is a desirable condition. The material is then quartered

so as to obtain eight portions of equal mass (6 - 7 kg is required per portion). Five portions are used for the

moisture-density test and are kept under damp sacks to avoid loss of moisture. The other three portions may be

returned to air-tight tins.

Hygroscopic moisture - The determination of this is no longer necessary.

Admixture of water - The optimum moisture content for the dry density can be obtained by plotting the wet

density against an assumed moisture content (which is the estimated moisture content plus the nominal percentage water added) on the Form A8/3. It can also be obtained by plotting the computed dry density as

described in Method A7. As the moisture content of the material used for the moisture density test and for the

CBR test is the same (because of the moistening beforehand), the same percentage water required to achieve

optimum moisture content on the preliminary moisture-density curve is added to the material. It is not

necessary to carry out a check moisture content with the view to adjusting the moisture content. After the

mixing in of the water, the material is kept under a damp sack, ready for compaction.

Compaction - Immediately prior to compaction a sample of ± 1 000 gram is taken to determine the moisturecontent, and the material is compacted as described above.

If the duplicates of the moisture content determinations differ by more than 0,5 per cent, another determination

ought to be carried out and the average of the two with the best agreement taken.

In calculating the required amount of water to be admixed, it is advisable to allow for evaporation duringmixing by adding slightly more water, say 0,1 to 0,3 per cent, depending on weather conditions.

If the penetration piston is attached to the penetration machine, a load of 45 N should be applied to the piston

before the dial gauge is set at zero. This load is the same as the weight of a loose piston and ensures that the

piston is truly seated.

The penetration is continued beyond 7,62 mm to allow for an extension in the stress-strain curve if a correction

is required which results in a considerable shift of the zero depth of penetration .

The material may also be compacted with a mechanical tamping machine, provided:

(a) that it complies with the requirement regarding density as set out in Method A7,Section 5.4;(b) that the tamper face is of the same shape and diameter as the hand tamper; and

(c) that the spacing of the blows is the same as with the hand tamper.A tamping machine with a triangulartamper face is. therefore, not acceptable.

Particular care should be taken with materials which do not adhere to the side of the mould and are liable to

drop out of the mould if the mould is handled without the base plate. In this instance, after the surface of the

moulded material has been finished off, a weighed soaking plate and wire gauze are inverted over the top of the

moulded material on which a round of filter paper has already been placed. The soaking plate is screwed into

position and the whole assembly, including the base plate, is inverted. The base plate with the spacer plate, is

removed carefully and the mould, material and soaking plate are weighed.

When granular materials are compacted, it will be found that the filter paper on the spacer plate side of the

moulded material becomes fractured and should be covered with a fresh round of filter paper before placing the

perforated plate with stem in position.

Although it is not necessary to determine the volume and mass of the moulds for each test, these should,nevertheless, be checked regularly.




FORM F – CBR graph sheets




Figure 19.2 – Example of CBR test




20. Dynamic Cone Penetrometer tests and analysis

IntroductionThe Dynamic Cone Penetrometer (DCP) is an instrument which can be used for the rapid measurement of the in

situ strength of existing flexible pavements constructed with unbound materials. Measurements can be made

down to a depth of 800 mm or to a maximum depth of 1500mm by adding an extension rod. Where the

pavement layers have different strengths, the boundaries between them can be identified and the thickness ofeach layer determined.

The DCP

The TRL DCP uses an 8 Kg hammer dropping through a height of 575mm and a 60° cone having a maximumdiameter of 20mm. The instrument is assembled as shown in Figure 1. It is important that the three screwed

joints connecting handle and upper shaft, coupling (referred to as the ‘anvil’) and upper shaft, lower shaft andcone are kept tight at all times with “Loctite” or similar non- hardening thread locking compound prior to use(1)

. Operating the DCP with any loose joints will significantly reduce the life of the instrument.




Operation and recording of data

After assembly, the first task is to record the zero error of the instrument. This is done by holding the DCP on a

hard flat surface such as concrete, checking that it is vertical, and then entering the zero reading in the

appropriate place on the DCP Test Data Form shown in Figure

3.

Prior to testing, site details should also be recorded on the Test Data Form. These include:

Chainage (km)

Location - either Carriageway, Shoulder, Verge or other

Lane number – 1/2/3/4 if the location is carriageway Offset (m) As defined by user

Direction

Cone angle – either 30o

/ 60o

cone

Zero error (mm)

Test date

Remarks, if any to a maximum of 60 spaces

Layers removed – None, One or Two

Surface type – either Thin Bituminous Seal, Hot Mixed Asphalt, Unpaved, Concrete or Other

Thickness of surfacing, if removed (mm)

Surface condition – where the road has a bituminous surfacing Strength coefficient of surface, if surface condition unknown

Base type – either Bituminous, Cement treated or Coarse granular (Water Bound Macadam)

Thickness of base, if removed (mm)

Strength coefficient of base, if removed

The DCP needs three operators, one to hold the instrument, one to raise and drop the weight and a technician to

record the readings as shown in Figure 20.1. The instrument is held vertical and the hammer lifted to the

handle. Care should be taken to ensure that when the hammer is raised, it does not ‘lift’ the instrument and just

before the hammer is allowed to drop it is just touching the handle. The operator must let it fall freely and not

partially lower it with his hands.

Figure 20.1 - Dynamic Cone Penetrometer in operation

Readings should be taken at increments of penetration of about 10mm. However, it is usually easier to take a

reading after a set number of blows. It is therefore necessary to change the number of blows between readingsaccording to the strength of the layer being penetrated. For good quality granular bases, readings every 5 or 10

blows are usually satisfactory but for weaker sub-base layers and subgrades readings every 1 or 2 blows may be




appropriate. There is no disadvantage in taking too many readings but if readings are taken too infrequently,

weak spots may be missed and it will be more difficult to identify layer boundaries accurately.

After completing the test the DCP is removed by tapping the hammer upwards against the handle. Care should

be taken when doing this; if it is done too vigorously the life of the instrument will be reduced.

The DCP can be driven through thin bituminous seals but thick hot mixed asphalt surfacings should be cored

prior to testing the lower layers. Little difficulty is normally experienced with the penetration of most types of

granular or lightly stabilised materials; however it is more difficult to penetrate strongly stabilised layers,

granular materials with large particles, and very dense, high quality crushed stone. Penetration rates as low as

0.5mm/blow are acceptable but if there is no measurable penetration after 20 consecutive blows it can beassumed that the DCP will not penetrate the material. Under these circumstances a hole can be drilled throughthe layer using an electric or pneumatic drill. The lower pavement layers can then be tested in the normal way.

If only occasional difficulties are experienced in penetrating granular materials, it is worthwhile repeating anyfailed tests a short distance away from the original test point.

If, during the test, the DCP leans away from the vertical no attempt should be made to correct it because contact

between the shaft and the sides of the hole can give rise to erroneous results. If the lean becomes too severe and

the hammer slides down the hammer shaft, rather than dropping freely, the test should be abandoned and the

test repeated approximately one metre away.

If the DCP is used extensively for hard materials, wear on the cone itself will be accelerated. The cone is a

replaceable part and it is recommended that it should be repl aced when its diameter is reduced by 10 per cent.

However, other causes of wear can also occur hence the cone should be inspected before every test.

Test spacing Sampling frequency will depend on the objective of the testing. Table 1 below gives recommended minimum

distances between DCP tests.

Objective Minimum test spacing

Routine testing for the rehabilitation of paved roads 500m or less

Areas of distress in paved roads 100m or less

Upgrading of gravel roads to sealed roads 500m or less

Design of spot improvements 50m or less

Interpretation of results

DCP results can be analyzed in a standard spreadsheet.

SummaryDCP provides essential information on the thickness and strength of the pavement layers using data collected

during DCP tests. Its capability for dividing the road into smaller section of uniform characteristics greatly

simplifies the task of interpreting DCP test data.




Table 20.1 - DCP Test Data Form

Chainage (Km): Layers removed: None One Two

Location: Surface type: Thin Bituminous Seal / HMA /

Unpaved / Concrete / OtherLane number:

Offset (m): Surface condition: 1 2 3 4 5 Unknown

Direction: Strength coefficient(if condition Unknown):

Cone angle 30o / 60

o : Surface thickness (mm) (If removed):

Zero error: Base type (If removed) : Bituminous /

Cement treated / Coarse granularTest date:

Remarks: Base thickness (mm) (if removed)

Strength coefficient of base(if removed)

No of

blowsDepth (mm) No of blows Depth (mm) No of blows Depth (mm)

1. 33. 65.

2. 34. 66.

3. 35. 67.

4. 36. 68.

5. 37. 69.

6. 38. 70.

7. 39. 71.

8. 40. 72.

9. 41. 73.

10. 42. 74.

11. 43. 75.

12. 44. 76.

13. 45. 77.

14. 46. 78.

15. 47. 79.

16. 48. 80.

17. 49. 81.

18. 50. 82.

19. 51. 83.

20. 52. 84.

21. 53. 85.

22. 54. 86.

23. 55. 87.

24. 56. 88.

25. 57. 89.26. 58. 90.

27. 59. 91.

28. 60. 92.

29. 61. 93.

30. 62. 94.

31. 63. 95.

32. 64. 96.




Table 20.2

Calibration of the Dynamic Cone Penetrometer

mm / blow Assumed % CBR

<4 50+

5 50

6 40

7 33

8 28

9 25

10 22

11 20

12 18

13 17

14 16

15 14

16 13

18 12

19 10

20 9

23 8

25 7

28 6

38 5

45 4

60-70 3

80-90 2

>100 1



References:

1. K. H. Head. Manual of Soil Laboratory Testing. Vol.1 Pp. 302309.

2. B.S. 1377: Part 4. Pp. 211.

3. R. F. Craig. Soil Mechanics. Pp. 2736.

4. AASHTO Designation T90-61

5. AASHTO Designation T193-63

6. ASTM Designation D424-59

7. ASTM Designation D1883-67

8. ASTM D 4318 - Standard Test Method for Liquid Limit, Plastic Limit, and Plasticity Index of Soils9. TMH1 – Second Edition 198610. ASTM. 424-59.

11. Bowles, J.E. 1979. Physical and Geotechnical Properties of Soil.12. McGray-Hill Inc.

13. McKeague, J.A. 1978. Manual on Soil Sampling and Methods of Analysis

14. Edition. Can. Sot. of Soil Sci. Suite 907, 151 Slater St.,Ottawa, Ont.

geotechnical eng ii(s3) lab manual updated 1'2012

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