Main

Final internship Report 2005

Selamu Yihune Page i

ACKNOWLEDGMENTS

First of all, I would like to praise almighty God, who has been there for me all the times

when I was in need of him. Next to this I would like to thank my company supervisor,

Assistant Resident Engineer Ato Tekeste for his kindly advice and supervising

throughout the internship program.

My deep appreciation and many thanks go to my mentor Ato Tsehaye for his open

handed support and for directing me to focus on important issues. Without his guidance

and valuable supervision, i would not have this knowledge.

I would also need to thank the Material Engineer Ato Muluneh and the each staff of

Materials laboratory for their unreserved support and co-operation while conducting the

laboratory tests. Besides, I cannot step without mentioning that, honorable thanks to Ato

Kaleab Mame, who has helping me by answering all of my question and his friendly

advice.

I am deeply indebted and thankful to my team mates Abey and Setargew; they were a

constant source of encouragement. They also helped me in sharing knowledge and helped

me during execution of laboratory tests.

Finally I want to pass grateful acknowledgement for Laboratory Technicians, Work

Inspectors, and laboratory assistant, and for those person I have received valuable

assistance either in word or in material, those who have been beside me in the internship

program.


Selamu Yihune Page ii

EXECUTIVE SUMMERY

This report is an outcome of the exercise I conducted during my internship period at

Gondar-Debark road upgrading project. This was an opportunity for me to put in practice

the theoretical knowledge I had gathered during my three years of study at Bahir Dar

University.

The purpose of this report is to put in writing the work experience I had performed and

the learning attained from performing specific tasks while working in a professional

environment.

In the first part of my report, I briefly described the back ground of my internship hosting

company, including the history and objectives of the company, its main products and

services, the overall organization and work flow. I also explained the background of the

project like its contract, alignment terrain, location, climate and typical cross sections.

The second part of my report briefly explains the overall internship experience I have

gained during my practical periods. I started by telling how I get into the company, in

executing. I also explained clearly what the general work flow in our site looks like.

The procedures I have used while performing my tasks, are also included in this part of

the report. I tried to explain all of my experience during this time, starting from the

earthwork like cutting and construction of embankment then I explained the material and

the steps we used during construction of pavement layers like sub-grade, sub-base, base

course, prime coat, tack coat and surface layer. After pavement layers I described about

the structures which is very use full for a goodly functioning highway like side ditches,

culverts, and retaining walls. Next to this I briefly described the objectives, main

principle and calculation of the laboratory tests I conducted during my internship time.

While I writing all the report I insert some tables and pictures which can express the

works easily and shortly.

The challenges I have faced during my internship period, both site challenges and

personal challenges are covered in this report.

The third part of my report briefly explains about the overall benefits and experience I

gained from my internship in terms of improving my practical skills, interpersonal

communication skills, team playing skills, leadership skills, upgrading my theoretical

knowledge and work ethics.

Finally, I covered my conclusions and recommendations for my hosting company.


Selamu Yihune Page iii

Table of contents

1. BACKGROUND OF THE INTERNSHIP HOSTING COMPANY .................................................... 1

1.1. Brief History of the Company ....................................................................................................... 1

1.2. The Main Product and Service of the Company ........................................................................... 2

1.3. .......................... 2

1.4. Overall Organization and Work Flow ........................................................................................... 3

1.5. Description of the Project ............................................................................................................. 6

2. OVER ALL INTERNSHIP EXPERIENCE ......................................................................................... 9

2.1. How I get in to the Company ........................................................................................................ 9

2.2. The Section of the Company I have been working ....................................................................... 9

2.3. The work flow in the sections:- .................................................................................................... 9

2.4. The work I have been executing ................................................................................................. 10

2.5. The Meaning and Procedures of the works ................................................................................. 11

2.5.1. Earthwork ............................................................................................................................ 11

2.5.2. Construction of Pavement layers ........................................................................................ 15

2.5.2.1. Sub-Grade ....................................................................... Error! Bookmark not defined.

2.5.2.2. Sub-Base ......................................................................................................................... 15

2.5.2.3. Base course ..................................................................................................................... 17

2.5.2.4. Bituminous Prime Coat ................................................................................................... 18

2.5.2.5. Asphalt Concrete Layer (Surface Course) ...................................................................... 19

2.5.3. Construction of Structures .................................................................................................. 22

2.5.3.1. Drainage structure ........................................................................................................... 22

Side Ditch ........................................................................................................................ 22

Minor Drainage Structures .............................................................................................. 23

Slab culvert ...................................................................................................................... 23

Box Culvert ..................................................................................................................... 23

Pipes culvert .................................................................................................................... 24

2.5.3.2. Retaining wall ................................................................................................................. 24

2.5.4. Laboratory Tests I Have Been Executing .......................................................................... 25

2.5.4.1. Tests on Asphalt (Bitumen) ............................................................................................ 25

Asphalt Penetration Test ................................................................................................. 25

Softening Points of Bitumen ........................................................................................... 26

Ductility Test ................................................................................................................... 27

Cut back distillation test .................................................................................................. 27

2.5.4.2. Tests on Asphalt Mixture ................................................................................................ 28


Selamu Yihune Page iv

Extraction of bitumen and mechanical analysis of extracted aggregate .......................... 28

Maximum Theoretical Specific Gravity of Bituminous Paving Mixture ........................ 29

Asphalt concrete mix resulted by marshal method ......................................................... 30

2.5.4.2. Tests on soil and aggregate ............................................................................................ 30

Atterberg limit test .......................................................................................................... 30

Particle size distribution wet sieve ............................................................................... 31

Aggregate Shape Test...................................................................................................... 32

Specific Gravity of Aggregate ......................................................................................... 33

Absorption Aggregate ..................................................................................................... 33

Los Angeles Abrasion Test (LAA ................................................................................... 33

Aggregate Crushing Value (ACV) .................................................................................. 34

Ten Percent Fines Value (TFV) ...................................................................................... 35

Proctor Compaction Test (Modified Proctor) ................................................................. 35

California Bearing Ratio (CBR) ...................................................................................... 36

2.5.4.3. Tests on the site ............................................................................................................... 37

Density of Soil in Place by Sand-Cone Method ........................................................... 37

Core cut ........................................................................................................................... 38

Application of Bituminous Coat ..................................................................................... 38

2.5.4.4. Tests on concrete ............................................................................................................ 39

Compressive strength test................................................................................................ 39

Mortar test ....................................................................................................................... 40

Slump Test ...................................................................................................................... 40

2.6. The Challenges I faced and the measures I took while performing my Tasks ............................ 41

3. Overall Benefits I got from the internship .......................................................................................... 42

3.1. Improving my Practical skills ..................................................................................................... 42

3.2. Upgrading theoretical knowledge ............................................................................................... 43

3.3. Improving my interpersonal communication skills ..................................................................... 43

3.4. Improving my team playing skills .............................................................................................. 44

3.5. Improving my leadership skills ................................................................................................... 44

3.6. Understanding about work ethics related issues ......................................................................... 45

3.7. Entrepreneurship skills ................................................................................................................ 46

4. CONCLUSION AND RECOMMENDATION .................................................................................. 47

4.1. Conclusion .................................................................................................................................. 47

4.2. Recommendation ........................................................................................................................ 48

5. Reference


Selamu Yihune Page v

List of Figure

Fig. 1.1 Consultant Office Organizational Chart .

Fig. 1.2 Project Location Map

Fig. 2.1 cut (rock and soil excavation) . 2

Fig. 2.2 construction of embankment

Fig. 2.3 Construction of Base Course

Fig 2.4 Application of prime coat

Fig 2.5 Tack coat 19

Fig. 2.6 Construction of Bituminous Surface Course .. 1

Fig. 2.7 Construction of Side Ditches ..

Fig. 2.8 slab culvert .

Fig. 2.9 box culvert

Fig. 2.10 Pipe Culvert

Fig. 2.11 Construction of Retaining Wall

Fig. 2.12 Execution of Asphalt Penetration Test. 26

Fig. 2.13 Execution of Softening Point Test 26

Fig. 2.14 Execution of Ductility of Bitumen Test . ..

Fig. 2.15 Execution of cut-back distillation test ..

Fig. 2.16 Extraction Equipment ... 29

Fig. 2.17 Vacuum Vessel 29

Fig. 2.18 Marshal Method, for stability and flow

Fig 2.19 Atterberg limit test using Cassagrande Cup Method .. 31

Fig. 2.20 sieve analysis 32

Fig. 2.21 flakiness sieve 32

Fig. 2.22 LAA Test Equipment 34

Fig 2.23 ACV test .. 34

Fig. 2.24 Proctor Compaction Test 36

Fig. 2.25 Execution of CBR Test 37

Fig. 2.26 Execution of Field Density 37

Fig. 2.27 Core Cutter Machine ... .. .38

Fig. 2.28 Measurement of Application Rate ... . 39

Fig. 2.29 Measuring Compressive Strength of Concrete 39

Fig. 2.30 Effect of raining on base course 41


Selamu Yihune Page vi

List of Table

Table 1.1 Terrain classification ...

Table 2.1 cut slope 12

Table 2.2 Inspection and test plan for: embankment, capping layer and sub-grade 15

Table 2.3 Inspection and test plan for: sub base materials 16

Table 2.4 Grading requirements for sub base material

Table 2.5 Inspection and test plan for: base course 17

Table 2.6 Grading requirement of base course material 18

Table 2.7 Inspection and test plan for: Coarse Aggregates (Asphalt concrete).. .. 20

Table 2.8 Gradation Requirement of Asphalt Aggregate 20

Table 2.9 Asphalt Mix Requirement 20

Table 2.10 Temperature of the mix 21

Table 2.11 Inspection and test plan for: Masonry stone 22

Table 2.12 The range at which the volume of distillate must lie 28

Table 2.13 Gradation of Asphalt Aggregate 28


Selamu Yihune Page 1

1. BACKGROUND OF HOSTA GE COMPAN

1.1. BRIEF HISTORY OF THE COMPANY

Foundation

The origins of J. Burrow Limited dates back to 1963, when an entrepreneurial Civil Engineer by

the name of John Burrow established an Engineering Consulting practice in Lusaka, Zambia.

The firm then known as John Burrow & Partners, rapidly expanded to become a leading provider

of Civil and Structural Engineering design and construction services in the East and Southern

African regions. When the development of primary infrastructure services were being developed

in these areas, John Burrow & Partners became one of the leading engineering service providers

with an enviable track record in providing a successful service.

Expansion

By the mid-eighties, from its African roots the company had expanded to a sizable operation

with an unblemished track record and reputation for delivering reliable, relevant and high quality

consulting services. The company was represented in over a dozen countries on the African

Continent & the United Kingdom and from this base was executing assignments in countries as

far afield as Thailand, Malaysia and China. In order to improve its operational efficiency and

management effectiveness a decision was taken to form two separate entities for the United

Kingdom & African based operations. This gave rise to John Burrow & Partners Overseas which

held all the African business units.

During the following two decades John Burrow & Partners Overseas went through three

ownership and name changes. The company also implemented a policy of local capacity building

and empowerment of local professionals by grouping the businesses into stand-alone enterprises

in Zambia, Botswana, Zimbabwe and Swaziland. The local professionals in each of these

subsidiary companies were then invited to become majority shareholders, thus creating leading

consulting engineering firms in each of these four countries.

The Present

From the 1st January 2006 the company became known as J Burrow Limited and has

operational bases in South Africa, Zambia, Swaziland & Zimbabwe with project offices in

Uganda, Tanzania, Mozambique, Sierra Leone and Zanzibar.

J. Burrow Limited now has significant experience at delivering Engineering and Project

Management services for the development of infrastructure in Africa. The Company and its

professionals are thoroughly familiar with the requirements of Multilateral development finance

agencies like the World Bank, European Union and the African Development Bank; and

Bilateral institutions like the United States Agency for Aid and Development, Japan International

Corporation Agency and the Kuwaiti Fund for Economic Development.



To support integrated project development, J. Burrow assembled multidisciplinary teams of

professionals comprising engineers, construction and project management specialists,

environmental scientists, planners, financial analysts, business modelers, project finance

specialists, lawyers and insurance experts.

Some works (products or service) of the company:-

A long distance bulk water transfer project, Botswana

Construction of 360 km (1.1 to 1.4 m diameter) pipeline to transport water from a Dam at

Letsebogo River in Northern Botswana to the towns and cities in the populated Eastern

corridor of the country, including the capital city Gaborone.

Upgrading a gravel road to bitumen paved standard, Tanzania

The Manyoni - Singida section (122 km) on the Central Transport Corridor was upgraded

to bitumen standard utilizing a design and build contract model.

Road Rehabilitation, Sierra Leone

Rehabilitation of the 164 km long Masiaka-Bo Highway.

1.2. The Main Product and Service of the Company

J. Burrow Limited provides professional services for the development of infrastructure which

include:

Intercity motorways, trunk roads or urban streets

Systems for the abstraction, treatment and supply of water; or solutions for collecting,

treating and reusing or disposal of wastewater.

Plant or network for the generation, transmission and distribution of power.

1.3. ct

or Service

As I have mentioned above, on the history, the company can provide different kinds of

consultation (product or service) on civil infrastructure. These are the main products of this

company, but as I am working on highway construction I will only describe the end users of this

highway construction and the advantages they have gained from it.

It is known that highway is public service which is constructed to help peoples rather than to

make profits. And as a public service all the peoples along the road and our country Ethiopia

are also the main users of the product of the company (which in this case is Highway). Some of

the advantages that the peoples along the highway gained are getting fast and easy access to

referral hospitals and preparatory schools which are not available in small towns, safe journey



The federal democratic republic of Ethiopia represented by the Ethiopian road authority (ERA)

endeavors to upgrade the Gondar-Debark road in order to meet the requirements of the increased

socio-economic activities along the project road corridor. These upgrading and construction of

environment like:-

Increase the national integrity of peoples of the country.

Promotion and enhancement of social and economic development along the project road

corridor;

Reduced vehicle operating cost ( e.g. fuel consumption, maintenance cost);

Increase road safety;

Reduced travel time and greater comfort to motorist;

Reduced noise and air pollution as well as dust nuisance.

Basically (Ethiopian Road Authority) ERA and other governmental and nongovernmental

organizations are the customers of this construction company.

1.4. Overall Organization and Work Flow

Resident engineer:- the resident engineer is accountable to the engineer (j. Burrow company).

matters related to construction of

the works like liaise with the regional officials and other institutions for right-of-way issues and

others. He has a responsibility to monitor progress of the works, monitor contractor's equipment

& manpower availability

the contractor, the consultant and era's representatives, perform periodic inspection and make all

the necessary changes in design, review and approve quantities and payment certificate.

Assistant resident engineer:- Assistant Resident Engineer is accountable to Resident Engineer.

He is the one who assist the Resident Engineer in all aspects and perform all the duties of the

Resident Engineer during his absence and follow up the activiti

actively engage in the design review process and makes all the necessary changes. He has a

responsibility to inspect the fieldwork daily and recommend solutions of problems to the

Resident Engineer and perform survey of the road geometry and keep continuous monitoring of

all changes regarding road geometry, roadside furniture and other facilities. He checks drawings,

plans, calculations, measurements and payment certificates prepared by the Contractor.

Pavement/material engineer:- Material Engineer is accountable to Resident Engineer. He is the

one who directly concerned with construction material. He assists the Resident Engineer in

approving or rejecting construction materials, also locate possible sources of construction

materials. And visit the site to solve major problems concerning subsurface conditions,

construction materials and pavement. He controls and assists the laboratory technician in

devising appropriate sampling and testing programs.



Geotechnical engineer:- Geotechnical Engineer is accountable to Resident Engineer. And

perform the necessary reviews on design documents pertaining to geotechnical investigation and

associated design. He inspects at periodic intervals the quality of the works, also visit the site to

solve major problems.

Highway engineer:- Highway Engineer is accountable to Resident Engineer. He makes the

necessary reviews on design, drawings and quantities to make the design changes to suit site

conditions and inspects the site at periodic interval to solve outstanding problems regarding the

design of the roadway, minor structures and other facilities.

Structural engineer:- Structural Engineer is accountable to Resident Engineer. He inspects the

works at periodic intervals to solve major problems concerning major and minor drainage

structures. And he inspects the structures for the proper interpretation of design drawings and set

inspection and testing requirements to be used by the Structural Inspector.

Claim expert:- He is accountable to Resident Engineer. And assist the Resident Engineer in all

contractual matters and interpretation of the tender document. He provide the necessary services

in examining Claims, assist during negotiations, and make the necessary cost break down

analysis for new items as well as escalated items.

Quantity surveyor:- Quantity Surveyor is accountable to Assistant Resident Engineer. He has a

responsibility to monitor the quantities of all pay items routinely and as requested by the

Contractor and make measurements of all works done by the Contractor as appropriate.

Senior surveyor:- Senior Surveyor is accountable to Assistant Resident Engineer. He has a

regarding the lines, levels and sections of finished works.

Draftsperson:- Draftsperson participates in the preparation of reviewed drawings, review all

working drawings received from the Contractor. Generally perform any drafting works needed

by the Consultant staffs for the use in the project



CONSULTANT OFFICE ORGANIZATIONAL CHART

Fig. 1.1 Consultant Office Organizational Chart

The Engineer J.BURROW

Project Director

Resident Engineer

Sociologist

Head Office Support

Claim Expert

Highway Engineer

Structural Engineer

Geotechnical Engineer

Assistant Resident Engineer

Secretary

Quantity Surveyor Pavement/Material

Engineer

Work Inspector Senior Surveyor Lab. Technician

Surveyor

Draftsperson

Lab. Assistant



1.5. Description of the Project

The Gondar -Debark road is located in the North part of Ethiopia which is the major links road of

the Amhara and Tigray regional states which are at border with Sudan and has approximately

99.90Km long.

The project is an upgrading of the existing gravel road to an asphalt road standard which was

built years ago as Telford base and penetration macadam during the period of 1936/40 and being

deteriorated for several periods that haltered the socio-economic condition. The road has a

prominent important as it located along the most scenic area of tourism to simian mountain in

addition to the various tourist location from the tourist town of Gondar to Debark.

The contract project was awarded to SINOHYDRO CORPORATION LTD; contractor and

construction supervision to J. BURROW South Africa LTD in association with OMEGA

Consulting Engineers, consultant. And accordingly the construction of project contract was

commenced on April 1st 2009. Originally the preliminary study of review of feasibility study,

Environmental Impact Assessment (EIA), Review of Detailed Engineering Design and Tender

documents was made by the KOCKS CONSULT GERMANY in JV with Metaferia Consulting

Engineers under the contract made on November 29th 2005. The above preliminary design as

well as construction of the project was made by the contract agreement with ERA (Ethiopian

Road Authority) under the financial grant of World Bank. The accepted contract amount of

money is 744,612,013.580 ETB.

The road was now planned to upgrade the road to an asphalt road standards and the road is to be

upgraded to 7m carriageway with 1.5m hard shoulders. The works include earthwork,

construction of pavement with bituminous AC surface, repair/rehabilitation of existing bridges,

construction of a new bridge, rehabilitation of minor drainage structures.

The improvement/upgrading include the provision of a 2*3.50m wide carriage way paved with

5cm asphalt concrete and gravel shoulders of 1.50m width in general and near major towns the

carriage way is widened to 2*3.50m + 2*2.50m.

In line with the classification of the road network in Ethiopia and traffic volume (AADT) the

standard and a traffic class of T6 (km0+730 to km4+500) and T5 (km4+500 to km99+900)

according to ERA Geometric Design Manual.

The road passes through number villages of Weleka, Shembekit, Ambagergioes, Gedebiye,

Dabat, and Woken.

Most of the existing major structures, bridges, culverts between Gondar and Debark are arch

structures of stone masonry type, other types are concrete pipes, slab culverts where by 16 small

to large bridges of which 4 will be removed and replaced and 10 will be rehabilitated with one



will be retained and one will also be extended. In addition there are 332 culverts to be extended,

replaced or maintained based on the hydraulic reassessment of the areas in line with the

structural integrity of the existing structures and improved geometric designs.

Alignment and Terrain

The start of the project is at Gondar with altitude of 2300m and varies the altitudes from its peak

of 3000m at km 34.10 and reaches 2870m at Debark town.

Table 1.1 Terrain classification

No. Terrain Chainages (km )

From To

1 Hilly 0+732 , 15+400 4+603, 27+948

2 Rolling to Hilly 4+603 ,95+984 9+441,99+900

3 Rolling 9+441,27+948 10+957,95+984

4 Mountainous 10+957 15+400

Climate

The temperature of the project area is basically altitude induced and it is predominately cool

highland temperature. In day time temperature rarely rises above 30C in Gondar and 25C in

debark and rarely fall below 10C and 6C respectively. The average mean temperature is 21C

in Gondar and 14C in Debark. The mean annual rainfall in the project area varies between

980mm and 1,100mm.

Location Map

The project road is located in Amhara National Regional State in the northern part of Ethiopia. It

ween longitude 37-38 and Latitude 12-14

north.

Typical Cross sections

The road, in general, will have a 7m wide carriageway and 1.5m wide gravel shoulder on both

sides. In town sections the shoulder will be 2.5m wide and surfaced. In mountainous /very hilly

terrain/ the shoulder on the hilly side is provided as 1.50m wide, which has the combined

function of shoulder and longitudinal drainage.



PROJECT LOCATION MAP

Fig. 1.2 Project Location Map



2. OVER ALL INTERNSHIP EXPERIENCE

2.1. How I get in to the Company

I get in to the company by giving the letter, which was given to us by the University Industry

Linkage (UIL) office, to ERA (Ethiopian Road Authority) main office. The Northern regime

Manger, Ato Abey, positively accepted the letter to give training as an intern student for four

months and wrote a letter to the Gondar-Debark road upgrading project office of J Borrow and

Omega consulting company in Ambagiorgis town. As I arrived on the project area the company

received me with a great hospitality.

Next to this the assistant resident engineer, Ato Tekeste, control me as a supervisor and guide me

to understand the whole system of the construction. Even though they received me and control

me, for the first one month I was really bored, because I was only watching the works, moving

month of watching I begun to take samples from site and execute the laboratory tests with my

friends.

2.2. The Section of the Company I have been working

The sections I have been working are:

Site inspection

Laboratory: Lab-Assistance

2.3. The work flow in the sections:-

Inspection

Site Inspection

This work is done for approving the work that is done by the contractor. The main responsible

person for this work is the site Inspectors and Laboratory Technician on that site. They have a

duty to control each steps of the works and made their own evaluation to approve the work.

Assistant Resident Engineer

Work Inspectors Surveyor Site Lab-Technician



Inspector: Inspectors are accountable to Assistant Resident Engineer. They are an authorized

representative of the Engineer assigned to make detailed inspections of the construction process

or contract performance.

Site Laboratory Technician: Site Laboratory Technicians are accountable to Assistant Resident

Engineer and Material Engineer. They are an authorized representative of the Engineer to make

detailed inspections of Materials quality and control execution of field tests. And perform

sampling and testing on sources of materials, stock piles and finished works.

Laboratory

Laboratory Technician: Laboratory Technicians are accountable to Material Engineer. They

have a responsibility to check/control the execution of the laboratory test and field tests. And

perform sampling and testing on sources of materials, stock piles and finished works.

Laboratory -Assistant: Lab-assistants are accountable to the laboratory technician. They have a

responsibility to control each and every steps of the execution of lab tests and field tests. They

record all the test results and check by their own self and transfer to laboratory technician.

2.4. The work I have been executing

In my internship time I have been executing different works in two sections of the company.

This works are inspection and execution of laboratory tests. Generally I have tried to cover the

basic works which are related to civil engineering works.

Material Engineer

Lab-Technician

Soil & Aggregate

Lab-Assistant

Asphalt

Lab-Assistant

Labors Labors



2.5. The Meaning and Procedures of the works

2.5.1. Earthwork

This Division covers all works in connection with the preparation of the natural in-situ material

on which the embankment or capping layers are to be constructed. It is the preparation of the

sub-grade prior to the construction of pavement layers.

Equipment used for the preparation of roadbed and sub-grade are the following.

Loader

Excavator

Roller

Grader

Bulldozer

Chain Excavator

Cut

Cut mean all excavations from the road prism including side drains. In this portion of the road

prism the material was excavated to sub-grade or road bed level. All cuttings excavated below

the specified levels were back-filled with suitable material and compacted to the desired level.

Some considerations are taken when cutting is done. These are:

Type of material to be excavated

Water table

Slope determination

Volume and position of materials

Drainage and protection against erosion

Type of material to be excavated

Type of material to be excavated governs the construction method, the suitability of the cut

material for the sub grade and slope that can be safely adopted. At the place where there is a

Black-Cotton soil, which has low bearing capacity, undercut of 50cm was applied, and back

filled with suitable material to the desirable level. At the place where there is a massive rock and

boulders, the use of explosive material like dynamite and rock cutting machine was applied.

Water table

A water table may be permanent or seasonal. In any case its presence and characteristics (level,

flow of water etc.) is determined, as they affect the method of excavation and stability of cut

slope and the drainage system.



Slope determination

The design slope of cut section is a compromise between the following requirements

Stability

Erosion

Appearance and visibility

Need of fill material

Minimum cost

Volume and Position of Different Materials:

Some materials need high energy to excavate and transport away from the excavation area. For

example at hilly place excavation by volume was considered.

Drainage and Protection against Erosion:

Cut section always needs drainage to drain out the water which comes from catchment area. For

the purpose of avoiding erosion, intercepting ditch was provided where slope of existing ground

is towards road and height of cut slopes exceeds 1m and it was constructed prior to the start of

earthworks. One meter of Berm at the foot of the cut slope was applicable where height of cut

slope exceeds 3m.

Fig. 2.1 cut (rock and soil excavation)

Table 2.1 cut slope

No. Material description Cut slope inclination (H:V)

1 Colluvial Deposit of Boulders, of Soils

or of Soil and Boulder

2:1 if condition permits, or else Retaining wall

2 Soil or common material 1:1

3 Decomposed Rock with Boulder 1:1 if condition permits, or else 1:2

4 Highly Decomposed Rock 1:1

5 Highly Weathered Rock 1:1

6 Decomposed Rock 1:2

7 Weathered Rock 1:4

8 Fresh or Hard Rock 1:10



Construction of Embankment (Fill)

Embankment are the portion of the road prism composed of approved fill material which lies

above the original ground and is bounded by the side slopes, extending downwards and outwards

from the outer shoulder breakpoints and on which the pavement is constructed. The materials

used for the construction of the embankment are called fill material or embankment material.

This materials usually comes from borrow areas within the vicinity, approved for the purpose of

this road construction and are used to replace unsuitable road material.

Embankment is classified as

Earth embankment and

Rock fill embankment

The following factors are taken in to the consideration during embankment construction

Foundation condition

Acceptable fill material

Stability of slope

Settlement

Foundation condition

Foundation condition beneath embankment requires special attention to avoid shear failure and

excessive settlement. Wherever an embankment is built, detail investigation is done to determine

the most suitable construction method.

Acceptable fill material

Sometimes fill materials were obtained from cuttings. If the material is not suitable, other

material is transported from the borrow areas to the embankment. The requirement of

embankment material is shown in table 2.2.

Stability of slope

The edge of embankment should have a stable slope. The stable slope preserves sliding of the

soil at the age of embankment by its weight or environmental actions. This is done with suitable

slope with respect to the soil type. The slope of embankment depends on Depth of fill and Types

fill material. In this project, general embankment slope is 3:2 (H: V), but for embankment height

less than 1m the slope is 2:1 (H: V) as instructed.

The Embankment was constructed as follows:-

The surveyors fixed the slope stick limits according the design data.

Any unsuitable material was removed and replaced with appropriate materials as per the

preparation of the road bed)



Field density test was done to check whether the necessary compaction have been attained at

the optimum moisture content.

After water showering, fill material was dumped.

The dumped fill material was placed at moisture content near the Optimum Moisture

Content (OMC) using Grader.

The placed material was compacted using Roller to attain 95% compaction on the field.

Fig. 2.2 construction of embankment

Sub-Grade

Sub-grade is the top portion of the natural soil, either undisturbed (but re-compacted) local

material in cut sections, or soils excavated in cut or borrow areas and placed as compacted

embankment. The type of subgrade soil is largely determined by the location of the road. The

Sub-grade level is the foundation on which the vehicle load and the weight of the pavement

layers finally rest.

The strength of subgrade for flexible pavement is commonly assessed in terms of California

Bearing Ratio (CBR). For this project the sub-

-base

but in some part, where black cotton soil is encountered, it constructed below the capping layer.

The Sub-grade was constructed as follows:-

The setting out work was done by surveyors.

The surface was showered over which the sub-grade layer is to be constructed

The subgrade material was dumped using Dam Trucks.

If the material to be used is dry water should be added and mix to attain the Optimum

Moisture Content, if the material is moist, it should be exposed to the sun to reduce moisture.

The material was placed by Grader following the pegs elevation.

To protect intrusion of materials the surface should be smooth and visually good.

The surface was compacted using single Roller to attain the desired field compaction level.



Capping Layer

Where very weak soils and/or expansive soils (such as black cotton soils) are encountered, a

capping layer is sometimes necessary. It consists of better quality subgrade material imported

from elsewhere or subgrade material improved by stabilization (usually mechanical), and may

also be considered as a lower quality sub-base.

For this project capping layer was provided in small area where there was black cotton soil is

encountered. The construction process of capping layer is the same as sub-grade layers

For the determination of the suitability of the material, the contract document established

material requirement for embankment, capping layer and sub-grade material as follows in table:

Table 2.2 Inspection and test plan for: embankment, capping layer and sub-grade

No Description Testing method Acceptance criteria conducted on

1 Max. particle size Visual 4% for Fill

>15% Capping

Field Lab

3 Percent swell AASHTO T-193



volume (Dam Trucks). The ratio is 1:2, means, one Dam Truck of crushed rock and two Dam

Trucks of natural soil from Borrow area. The thickness of the sub-base is 250mm for km0+730

to km4+500 (Traffic class T6) and 225mm for km4+500 to km99+900 (Traffic class T5).

The Sub-Base was constructed as follow:-

After setting out work was done by surveyors, the material came from the borrow pit

using Dam Trucks and dumped on the prepared sub-grade.

The material was thoroughly mixed, spread and arranged to the required (settled) width

and thickness. But segregation (pockets of fine and courser material) shall be avoided.

The Roller passed two or three times.

The shower truck showered the layer to satisfy the desired moisture content during

compaction and compacted with rollers until the desired compaction level was reached.

During leveling and compacting, the elevation was continuously checked by surveyors.

For the determination of the suitability of sub-base material, the contract document established

testing methods and requirements on materials properties as follows in table:

Table 2.3 Inspection and test plan for: sub base materials


1 Max. particle size Visual 30% Field Lab

3 LAA AASHTO T-96



2.5.2.3. Base course

Base course is a layer of material of specified dimension constructed on the top of sub-base. It is

the main structural part of the pavement contributing to the spreading of the traffic loads and it

provides a level surface for laying the surface layer. Base course materials must have a particle

size distribution and particle shape which provide high mechanical stability and should contain

sufficient fines (passing of 0.425 mm sieve) to produce a dense material when compacted.

Material source: For this project the material used for road base layer is crushed rock. It is

produced from crushing of rocks

The base course is found about 5 cm below the finished surface level. It has 200mm thickness

fromkm0+730 to km4+500 (Traffic class T6) and 175mm thickness from km4+500 to

km99+900 (Traffic class T5).

In most part of the road the base course and the shoulder are constructed from the same material

and constructed simultaneously. But at the place where the base course and the shoulder are

constructed from different material, the shoulders was first constructed and neatly cut to the

required line to provide lateral support for the base course.

Fig. 2.3 Construction of Base Course, it was the same as sub-base as expressed above

For the determination of the suitability of base course material, the contract document

established testing methods and requirements on materials properties as follows in table:

Table 2.5 Inspection and test plan for: base course


1 Grading AASHTO T-27 Sts. Table 5200/1 Field Lab

2 Plasticity index AASHTO T-90 100% Field Lab

4 LAA AASHTO T-96



Table 2.6 Grading requirement of base course material

Sieve Size Specification by % passing

63 100

50 100-90

37.5 100-80

25 51-80

10 70-35

5 -

2.36 -

0.425 -

0.075 5-15

Pan -

2.5.2.4. Bituminous Prime Coat

It is bituminous treatment applied to the surface of a newly constructed unbound road base prior

to the construction of a bituminous layer or surface treatment (generally it is an application of

liquid bituminous material to previously untreated base course surface). It serves:-

To consolidate the surface on which the new treatment is to be placed;

To promote bond between base and wearing surface;

To act as a deterrent to the rise of capillary moisture into the wearing surface;

No prime was applied under the following adverse conditions;

a) During foggy or wet conditions;

b) When the rain is imminent;

c) When the surface (base course) is wet, i.e. more than dump;

d) when wind is sufficiently strong to cause uneven spraying;

Note: Not more than 24 hours before spraying, the layer to be primed must be broom and cleaned

of all loose or deleterious material.

For this project, according to the contract document, the priming material should be MC-30

cutback bitumen and the application rate is 0.9-1.12 lit/m

Fig 2.4 Application of prime coat



Tack coat

A bituminous treatment applied to the surface of an existing bituminous layer prior to the

construction of a new bituminous layer. During construction, to give accesses to transportation

one of the lanes was constructed (finished) first. To continue the other, tack coat is used as a

binder of the two lanes. This material is rapid curing material with a composition of 60% of

water and 40% of bitumen mixed by the process of Emulsion. Bitumen is inert material to

combine with water the chemical called Dinorium is added. The material used for tack coat was

called RC-70 cutback bitumen.

Fig 2.5 Tack coat

2.5.2.5. Asphalt Concrete Layer (Surface Course)

It is a structural part of the pavement constructed on top of the road base, which is tough enough

to resist distortion under traffic and provide a smooth and skid resistant riding surface. It is the

layer of asphalt concrete, mixture of different gradation of aggregates, internal and external

fillers and asphalt cement, the highest quality material is necessary. To perform satisfactorily, the

finished bituminous layer needs to possess the following characteristics.

High stiffness in order to reduce the stresses in underlying layer.

High resistance to deformation.

The surface course must be waterproof to protect the entire pavement and subgrade form

the weakening effect of water.

High resistance to fatigue and ability to withstand high strain.

High resistance to the environmental degradation.

This work consists of furnishing and mixing aggregates with asphalt binder at a mixing plant to a

specific temperature, transporting, laying and compact the mixture on an approved primed or

tacked base in accordance with the specification.

Material source: The asphalt concrete layer is made from high quality crushed stone and

bitumen. Both the aggregate and the bitumen have to pass different types of tests that are done on

the design stage. The design was conducted based on marshal mix design method. The

aggregates used for asphalt concrete were produced from the quarry site located at km44+500

and mixed at the mixing plant located at km44+500. The total thickness of surface course is 5 cm

all over the length of the road (0+730 to 99+900).



Fillers: If the grading of the combined aggregates for asphalt surfacing mixes shows a deficiency

in fines, approved filler may be used to improve the grading. Filler may consist of active filler of

inert material such as rock dust having the required grading necessary to improve the grading of

the combined aggregates. In no instance shall more than 2% by mass of active filler be used in

asphalt mixes.

Table 2.7 Inspection and test plan for: Coarse Aggregates (Asphalt concrete)

No. Description Testing method Acceptance criteria conducted on

1 Grading AASHTO T-27 Sts. Table 6400/8 Field Lab

3 ACV BS 812-1990



The surface course was constructed as follows:-

The primed base was prepared using Air Compressor to remove dusts or unwanted material

To keep the temperature of mixture during transportation, the Tucks were covered.

The paver placed the mixture about 6.5cm depth.

Compacted by steel-tired and pneumatic-tired Roller. Then, it cooled and opened to traffic.

During compaction the Rollers shall be equipped with adjustable scrapers for cleaning the

drums and an efficient means of moistening the drums to prevent adhesion of asphalts.

Thing that we should note during compaction:-

On hilly areas the direction of compaction should be from the bottom to the top, this is

to protect the pavement layer from sliding down.

The compaction paths should be overlapped to each other; this is to avoid the bulging

of materials in between two paths.

On curves compaction should be started from inner side (smaller radius) of the road

curve and continues to the outer part, this is done to protect the super elevation from

sliding down.

Fig. 2.6 Construction of Bituminous Surface Course

At all stages the work inspector check the temperature of the asphalt mix. If it is below the

acceptable temperature the contractor has to remove the asphalt mix.

Table 2.10 Temperature of the mix

Measurement taken at

Temperature c

Loading the truck at the plant 145-170

The truck reaches the site 145-150

The finisher paves 135-145

The steel roller makes compaction 120-125



2.5.3. Construction of Structures

2.5.3.1. Drainage structure

Adequate and economic drainage is absolutely essential for the protection of the investment

made in highway and for safeguarding the lives of the person who use it. The measures taken to

control the flow of surface water is generally termed as surface drainage. In surface drainage

system, the water is first collected in longitudinal drains, and then disposed to the nearest stream,

valley or watercourse. Cross drainage structures like culverts and small bridges may be necessary

for the disposal of surface water from the roadside drains. Road surfaces are normally crowned

to facilitate the removal of surface water from the surface trough cumber slope. The materials

(aggregate, sand, masonry) used for the construction of drainage structures are tested properly

and must qualify the requirements of the contract document.

Table 2.11 Inspection and test plan for: Masonry stone

No. Description Testing method Acceptance criteria conducted on

1 Specific gravity AASHTOT-85-94



All of these ditches the thickness of stone is 20 cm. The slope used for side ditches are the same

as those used on centerline of the road. In major town sections, due to the limitation of land

width, underground longitudinal drains (pipes or U-shaped with ditch cover) were provided on

both sides. They are made from concrete and stones. The concrete is mixed with ratio of 1:3 and

has a grade of C-30/20 (C-30 and maximum aggregate size is 20mm)

Minor Drainage Structures

Minor drainage structures are structure, other than Bridge, which provide an opening under the

carriageway for drainage. And used where bridges are not hydraulically required, where debris is

tolerable, and where they are more economical than a bridge. Whenever streams have to cross

the roadway, facility for cross drainage is to be provided. The water from the side drain is taken

by those cross drains in order to divert the water away from the road, to a watercourse or valley.

Slab culvert

In slab culvert, RC slab is placed over abutments made of masonry and the span is generally

limited to 4.5m. They are usually specified for larger flow than pipe culverts. Headwall and

Wing walls are provided to protect the sides of the embankment against erosion. The upstream

wall is called headwall and the downstream is called end wall. In this project this culverts are

constructed from a concrete of grade C-30/20

Fig. 2.8 slab culvert

Box Culvert

Concrete box culverts are constructed with a square/rectangular opening, made from reinforced

concrete (RC) with wing walls at both ends. They are usually specified for larger flows and

where the area of the foundation soil is weak (exposed to differential settlement). Headwall and

Wing walls are provided to protect the sides of the embankment against erosion.

In this project this culverts are constructed from a concrete of grade C-30/20



Fig. 2.9 box culvert

Pipes culvert

They are locally produced and economical. They have bell and spigot joints, which are sealed

during construction with Portland mortar. The foundation on which the pipes laid could be a

natural bed or concrete cradle depending on foundation conditions and loads on the pipe. Pipe

culverts can often be placed particularly on lower volume roads without headwalls or wing walls.

They are constructed from a concrete grade of C-35/20.

During construction of all culverts, to create working

space the edge of excavation limit was 60cm away from

the edge of structure the foundation of the structures

were done by 10cm concrete bedding (lean concrete).

The back fill material was advised by Material

Engineer.

Fig. 2.10 Pipe Culvert

2.5.3.2. Retaining wall

Reta

the road is built up on it. At the place where there is a high cut and a high fill, the uses of

retaining walls is recommended. It used to retain the soil when the load is applied on it.

This Gondar-Debark road upgrading project comprises 15 stone masonry retaining walls. Five

retaining walls replaced the existing ones and ten new classes A masonry retaining walls are

constructed. The foundation of the stone masonry shall be prepared on the approved foundation

material. Where the foundation material is rock, 100mm thick layer of grade 15concrete was

used. And where the foundation material is other than rock, 100mm thick layer of crushed stone

compacted to 97% of its MDD and a second 100mm thick layer of grade 15 concrete was used.

The slope of the retaining walls is 3:8 (H:V) for front part and 1:8 (H:V) for the back. For the



purpose of drainage of the soil retained 10cm diameter weep holes are provided at every 3m

horizontally and 1m vertically. The walling is constructed with stones and 6:1 sand: cement

mortar. Before placing all the stones were thoroughly wetted with water. After completion the

walling should be protected from the elements and kept moist for a minimum period of four

days. The masonry used for this structure is tested according to table 2.6.

Fig. 2.11 Construction of Retaining Wall

2.5.4. Laboratory Tests I Have Been Executing

2.5.4.1. Tests on Asphalt (Bitumen)

Asphalt Penetration Test

Objective: The penetration test is used to measure consistency (hardness or softness) of solid or

semi-solid bituminous material.

Main Principle: The sample was melted and cooled under controlled condition. The penetration

was measured with penetrometer by means of which a standard needle was applied to the sample

under specified conditions. A needle (50.8mm length and 1/1.02mm diameter) was allowed to

penetrate vertically into a sample under specified load (100g), temperature (25C) and time (5 sec)

conditions. The distance the needle penetrates in units of 1/10 mm is termed as penetration value.

For each test a minimum of three valid measurements were performed, the locations on the

sample surface must be a minimum of 10 mm apart and away from the container side.

For this project the penetration value is expected to lie between 80 and 100 (80/100), because,

the average weather condition of the project area is cold weather (14C -21C). The higher

values of penetration indicate softer consistency, so we should use the softer bitumen for cold

weathered environment and vice versa.



Calculation: When the requirements in table above are met, calculate the average value to the

nearest whole unit (1/10-mm).

Fig. 2.12 Execution of Asphalt Penetration Test.

Softening Points of Bitumen

Objective: The softening point test is used to measure the temperature at which the bitumen shows

fluidit y. It is an indicative of the tendency of material to flow at elevated temperature encountered

in service. It is also useful in evaluating the uniformity of shipment or source of supply.

Main Principle: Two samples of bitumen were casted in shouldered brass ring. A steel ball of

3.5g was placed on a sample contained in brass rings and suspended in water. Water is used for

softening points of 80 C and below, and glycerin is used for softening points greater than 80 C.

The bath temperature is raised at 5 C/min, the binder gradually soften and eventually deform

slowly as the ball falls through the rings. At the moment the bitumen and steel ball touches the

base plate 25 mm below the ring, the temperature of water is recorded as softening point.

For this project the value should be 42C-45C, for hot weather condition the softening point

would be higher.

Calculation: The test was performed in duplicate, if the difference between the two does not

exceed 1C, the mean of the two measured temperatures is reported, which otherwise entails

test repetition.

Fig. 2.13 Execution of Softening Point Test



Ductility Test

Objective: The ductility test is used to describe the ductile and tensile behavior of bitumen. The

ductility of Bitumen is an indication of its elasticity and ability to deform under load and return

to original condition upon removal of the load. The result also indicates the extent to which the

material can be deformed without breaking.

Main Principle: the Bitumen sample was casted in the mold consisting of two jaws, and then

placed in a water bath of specified temperature (25C). One jaw moved (stretched) away from

the other at a standard rate of 50mm/min. The distance it moves before the thread between the

two break is the ductility in centimeters.

Calculation: The ductility of a bituminous material is measured as distance to which it will

elongate before breaking when two ends of a briquette specimen of the material are pulling apart

at a specified speed and at specified temperature. The Distance (cm) between the end clips in cm

when the test specimens break. For this project the value should lie above 100.00cm.

Fig. 2.14 Execution of Ductility of Bitumen Test.

Cut back distillation test

Objective: This test method covers a distillation test for cut-back asphaltic products. This

procedure measures the amount of the more volatile constituents in cutback asphaltic products.

Main Principle: Two hundred milliliters of the sample was distilled in a 500ml flask at a

controlled rate to a temperature in the liquid of 360C (680 F) and the volumes of distillate

obtained at specified temperatures are measured. The residue from the distillation and also the

distillate may be tested as required.

For this project this test is applicable for prime material. This material is a mixture of 60%

cutback asphalt and 40% of kerosene, MC-30. To check its composition we applied distillation.

And the result must lie within the specified range in the table below.



Table 2.12 The range at which the volume of distillate must lie

Description (C) Amount of distillate (ml) Specification

Temperature Test result in the cylinder Min Max

225 - 25

260 40 70

316 75 93

360

Calculation:- Asphaltic Residu- the volume percent residue(R) to the nearest 0.1 as follows:

R = [(200-TD)/200]100, TD%=(TD/200)100 w/r TD = total distillate recovered to 360C,ml.

Fig. 2.15 Execution of cut-back distillation test

2.5.4.2. Tests on Asphalt Mixture

Quantitative extraction of bitumen and mechanical analysis of extracted aggregate

Objective: These methods cover the quantitative determination of bitumen in hot-mixed paving

mixture. The aggregates obtained by this method may later be sieved to determine the aggregate

grading within the pavement material.

Main Principle: The paving mixture was washed (extracted) with trichloroethylene, using the

extraction equipment. The extracted aggregate again washed with soap to remove the solution

from the aggregate. Then bitumen content was calculated by the differences in mass of the

original sample and the oven dried extracted binder-free aggregate. Finally by making sieve

analysis for oven dried binder-free aggregate, we checked the gradation of the aggregate in the

pavement material.

For this project the amount of bitumen content should be 5.00.2%. And the mechanical sieve

analysis of extracted aggregate should lie between the specification (upper and lower limit)

Table 2.13 Gradation of Asphalt Aggregate Sieve(mm) 26.5 19 13.2 9.5 4.75 2.36 1.18 0.6 0.3 0.15 0.075 pan

% passing

Upper limit 100 97.2 84.5 74.8 58.7 43.0 28.0 21.5 15.2 11.7 10.6

Lower limit 100 87.2 74.5 64.8 50.7 35.0 20.0 13.5 9.2 7.4 6.6



Calculation: Bitumen content (%), I = H/A, w/r H=A-(B+F), H = Mass of bitumen

A = original (total) sample, B = mass of aggregate after extraction, F = mass of filler

Fig. 2.16 Extraction Equipment

Maximum Theoretical Specific Gravity of Bituminous Paving Mixture (MTD)

Objective: This method is used to determine the maximum theoretical specific gravity and density of

uncompacted bituminous paving mixture. It is also called the void-free density. Maximum

theoretical density is influenced by the compositions of mixture in terms of types and amount of

aggregates and bituminous materials. It is used to calculate air void in compacted asphalt mixture.

Main Principle: A weighted sample of oven-dry paving mixture in the loose condition was

placed in a tared vacuum vessel. Sufficient water at a temperature of 25 4C was added to

completely submerge the sample. To remove the entrapped air within the sample, vacuum was

applied for 15min. At the end of the vacuum period, the vacuum gradually released. And the

vacuum container with sample was immersed in to a water bath for 10 min. The volume of the

sample was obtained by measuring the mass of a vacuum container with sample and level full of

water, mass of the container filled with water, and mass of dry sample in air. If the temperature

employed is different from 25C an appropriate correction is applied.

Calculation: Maximum theoretical specific gravity (Gmm) = K*A/(A+B -C),

W/r A=mass of dry sample in air, B=mass of jar filled with water, C=mass of jar filled with water

and sample, k=water temperature correction.

Fig. 2.17 Vacuum Vessel



Asphalt Concrete Mix Resulted by Marshal Method (Conformtive Test for Mix

Design)

Objective: This method covers the measurements of the resistance to plastic flow and its

stability of cylindrical specimens of bituminous paving mixture (with max. aggregate size is

25.4mm) loaded on the lateral surface by means of the marshal apparatus.

Main Principle: A cylindrical Asphalt specimens, 1200gm of asphalt mixture compacted with

75 blows of 4.5kg mass on the top and bottom in 101.6mm diameter and 76.2mm high mold, are

loaded on the lateral surface by means of the Marshal apparatus at a specified loading rate and

temperature (60C). The resistance against plastic flow is measured.

This method works based on the determined optimum bitumen content for a particular grading

of aggregate which results good stability and flow that satisfies the requirement.

For this project the flow and stability should lie within 2 4 and minimum10KN, respectively.

Calculation: The Marshall stability is calculated by multiplying the maximum load value with a

correction factor depending on the specimen height.

Fig. 2.18 Marshal Method, for stability and flow

2.5.4.2. Tests on soil and aggregate

Atterberg limit test

The water content level at which the soil changes from one state to other are known as Atterberg

limits. It includes liquid limit (LL) and plastic limit (PL). it is determined using Casagrande cup

method.

Objective: Used to determine the moisture content at which the soil changes from liquid state to

plastic state and from plastic state to solid state, is called Liquid Limit and Plastic Limit

respectively. They are important limits of engineering behavior, because they facilitate the

comparison of water content at which the soil changes from one state to another. It also used to

determine the stiffness or consistency of the soil, which in turn depends on moisture content.



Main Principle: The liquid limi t (LL): is arbitrarily defined as the water content in percent at

which part of soil in a standard cup and a cut by a groove of standard dimension wil l flow together

at the base of the groove for a distance of 13 mm when subjected to 25 shocks from the cup being

dropped 10 mm in a standard liquid limi t apparatus operated at a rate of two shocks per second.

Plastic limit: The plastic limit (PL) is the water content, in percent, at which a soil can no longer be

deformed by rolling into 3.2 mm (1/8 in.) diameter threads without crumbling.

Plasticity index (PI): The Plasticity Index is the range of moisture content in which a soil is

plastic. It is the numerical difference between the liquid limit and plastic limit of the soil.

(PI=LL-PL).

Fig 2.19 Execution of LL and PL test using Cassagrande Cup Method

Particle size distribution wet sieve

Objective: A particle size distribution analysis is a necessary classification test for soils,

especially coarse soils, which contain relative portions of different sizes of particles. From this it

is possible to determine whether the soil consists of predominantly gravel, sand, silt or clay sizes

and, to the limited extent, which of these size ranges is likely to control the engineering properties

of the soil. For coarse and fine aggregates which are free from particles that cause agglomeration,

Dry Sieving may be performed. But for aggregates which may contain clay or other materials

likely to cause agglomeration, preliminary separation by washing through a fine sieve is required

before dry sieving, i.e. washing and sieving.

Main Principle: A minimum of 2.5kg sample were allowed to dry then washed the material

through 75m sieve, allowing the material passing sieve 75m to run to waste. All the retained

materials were dried in oven and sieved the dried fractions through the appropriate test sieve.

Finally weigh the amount retained on each sieve and any fines passing the 75 m test sieve and

record. The value of silt and clay can be obtained by difference of dried sample of before wash

and after wash.

Calculation: Calculate the cumulative percentage by mass of the sample passing each of the

sieves, from the general relationship: (% passing this sieve ) = (% passing previous sieve) - (%

retained on this sieve).



Fig. 2.20 sieve analysis

Aggregate Shape Test

Objective: The shapes of aggregate particles play an important role in pavement strength.

Aggregate particles may have rounded, cubical, anger, flaky or elongated shapes. Flakiness Index

and Elongation Index are one of the tests used to classify aggregates. For base course and

wearing course the presence of flaky and elongated particles are considered undesirable as they

may cause inherent weakness with possibilities of breaking down under heavy loads.

Main Principle: Flakiness Index: Aggregates are classified as flaky when they have the

thickness of less than 60% of their mean sieve size. The flakiness index of an aggregate

sample was found by separating the flaky particles using thickness gauge and expressing

their mass as a percentage of the mass of the sample. The test is not applicable to material

passing a 6.30mm test sieve or retained on a 63.0mm test sieve.

Calculation: FI=100(M1/M2), M1=Wt. of sample passing the gauge, M2=the sample

taken

Elongation Index: Aggregate particles are classified as elongated when they have a length

(greatest dimension) of more than 1.8 of their mean sieve size. The Elongation Index of an

aggregate sample was found by separating the elongated particles and expressing their mass as a

percentage of the mass of the sample. The test is applicable to material passing a 50 mm sieve

and retained on a 6.3 mm sieve.

Calculation: FI=100(M1/M2), M1=Weight of elongated particles M2= the sample taken

Fig. 2.21 flakiness sieve

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