Correlation Studies on Lab Cbr Test on Soil Subgrade for Flexible Pavement Design

CORRELATION STUDIES ON LAB CBR TEST ON SOIL

SUBGRADE FOR FLEXIBLE PAVEMENT DESIGN

TABLE OF CONTENTS

ABSTRACT..................................................................................................................vi

LIST OF TABLES......................................................................................................vii

LIST OF FIGURES....................................................................................................vii

Chapter-1: Introduction...............................................................................................11.1 General...........................................................................................................................................1

1.2 Background....................................................................................................................................1

1.3 Objectives.......................................................................................................................................2

1.4 Scope of work.................................................................................................................................2

1.5 Necessity.........................................................................................................................................2

Chapter-2: Literature Review......................................................................................3

Chapter-3: Methodology...............................................................................................73.1 Construction...................................................................................................................................7

3.2 Pavement Types.............................................................................................................................8

3.3 Properties of each layer...............................................................................................................113.3.1 Original Ground Level:.........................................................................................................................113.3.2 Low Embankment:.................................................................................................................................113.3.3 High Embankment:................................................................................................................................113.3.4 Sub-Grade:............................................................................................................................................113.3.5 Granular Sub-base:...............................................................................................................................113.3.6 Wet Mix Macadam:...............................................................................................................................12

Chapter-4: Design of Flexible pavement (IRC: 37-2001)........................................13

4.1 Traffic Volume data for Rajahmundry-Visakhapatnam in Jan-2012.......................................13

4.2 Computation of design traffic:....................................................................................................14

Chapter-5: Tests on pavement materials..................................................................175.1 Tests on soil..................................................................................................................................17

5.1.1 Introduction...........................................................................................................................................175.1.2 Free Swell Index (IS 2720 part-40).......................................................................................................185.1.3 Grain Size Analysis (IS 2720 part-4)....................................................................................................185.1.4 Consistency Limits and Indices (IS 2720 part-5)..................................................................................20

5.1.5 Compaction Test (IS 2720 part-8).........................................................................................................225.1.6 Field Density Test by Sand Replacement Method (IS 2720 part-28)....................................................245.1.7 California Bearing Ratio Test (IS 2720 part-16)..................................................................................25

5.2 Tests on Road Aggregates...........................................................................................................305.2.1 Introduction...........................................................................................................................................305.2.2 Aggregate Impact Test (IS 2386 part-4)...............................................................................................325.2.3 Specific Gravity and Water Absorption Tests (IS 2386 part-3)............................................................345.2.4 Shape Test (IS 2386 part-1)..................................................................................................................34

Chapter-6: Test Results..............................................................................................38

6.1 Low Embankment........................................................................................................................386.1.1 Grain Size Analysis:..............................................................................................................................386.1.2 Atterberg Limits:...................................................................................................................................406.1.3 Modified Proctor:..................................................................................................................................43

6.2 High Embankment:.....................................................................................................................466.2.1 Grain Size Analysis:..............................................................................................................................466.2.2 Atterberg Limits:...................................................................................................................................486.2.3 Modified Proctor:..................................................................................................................................51

6.3 Sub-Grade Soil:...........................................................................................................................546.3.1 Grain Size Analysis:..............................................................................................................................546.3.2 Atterberg Limits:...................................................................................................................................566.3.3 Modified Proctor:..................................................................................................................................586.3.4 CBR Value:............................................................................................................................................60

6.4 Mix Design for Granular Sub Base (GSB).................................................................................626.4.1 Abstract.................................................................................................................................................626.4.2 Specific Gravity and Water Absorption:...............................................................................................656.4.3 Individual Gradation.............................................................................................................................666.4.4 Blending Proportions:...........................................................................................................................72

6.5 Mix-Design for Wet Mix Macadam............................................................................................786.5.1 Gradation..............................................................................................................................................786.5.2 Flakiness Index & Elongation Index:....................................................................................................806.5.3 Aggregate Impact Value:......................................................................................................................826.5.4 Wet Mix Macadam Abstract..................................................................................................................846.5.5 Wet Mix Mecadam Design Summary....................................................................................................856.5.6 Laying of Wet Mix Macadam:...............................................................................................................86

Chapter-7: Substitute for Bitumen layer- Foamed Bitumen..................................887.1 Introduction.................................................................................................................................88

7.2 Foamed bitumen stabilization:....................................................................................................88

7.3 Recycled Aggregate:....................................................................................................................89

7.4 Technology involved:...................................................................................................................89

7.5 Spraying technology:...................................................................................................................91

7.6 Foamed Bitumen Classification:................................................................................................91

7.7 Advantages of Foamed Bitumen:................................................................................................92

7.8 Projects accomplished:................................................................................................................93

7.9 Case Studies:................................................................................................................................93

Chapter-8: Conclusions..............................................................................................95

References....................................................................................................................96

ABSTRACT

Transportation contributes to the economic, industrial, social and cultural development

of the country. The oldest mode of travel obviously was on foot paths. After the invention of

wheel, it became a necessity to provide a hard surface for wheeled vehicles. The flexible

pavements are built with number of layers. The design method of flexible pavement is based

on soil strength like California Bearing Ratio.

Gammon India Private Limited has taken up work under the Build, Operate and

Transfer (BOT) model to construct the 2nd road bridge across Godavari River. This structure is

named as YSR Varadhi. This is an 808-crore rupees mega project, out of which GIPL

will receive a grant of Rs: 207.55-crore from the Central and state governments. GIPL will

maintain this project for 25 years, which includes the construction period of three years. GIPL

has started this project in the year 2009. The 4.2-km-long road bridge includes 9-km approach

road from Diwancheruvu to Katheru and 2-km road in Kovvuru on the West Godavari side.

Once this YSR Varadhi is completed, the distance between Vijayawada-Rajahmundry-

Visakhapatnam will come down by about 30-50 km.

This particular project Correlation studies on lab CBR test on Soil Subgrade for

Flexible Pavement Design is completely focused on the approach roads connecting the

bridge on either side. The project describes the studies and estimations that are considered in

the earlier stages of construction of this project. The project includes various tests on soil and

aggregates. After arriving with the required data, the design of Flexible Pavement is done.

The next part includes the blending proportions and Mix-Designs for GSB and WMM layers.

The final objective of this project work is to introduce a better technology for the regular

bitumen layer. The regular bitumen is replaced with a new concept called Foamed Bitumen.

This material is cost-effective and more durable. Foamed Bitumen Technology is gaining a lot

of popularity in the world wide nations. This project work is an appeal to introduce this

innovative concept in India.

vi

LIST OF TABLES

Table 4.1: Traffic Volume data for Rajahmundry-Visakhapatnam in Jan-2012......................13Table 4.2: Vehicle damage factors for different traffic volumes..............................................14Table 4.3 IRC design Chart based on CBR value of 10%........................................................15

Table 5.1: Standard load values................................................................................................26Table 5.2: Types of compaction................................................................................................26Table 5.3: Aggregate Impact Values........................................................................................33Table 5.4: Maximum Limits for Aggregate Impact Value.......................................................33Table 5.5: Specifications for Thickness and Length gauges.....................................................36Table 5.6: Maximum limits for Flakiness Index.......................................................................37

Table 7.1: Classification of Foamed Bitumen..........................................................................91Table 7.2: Projects accomplished by using Foamed Bitumen..................................................93

LIST OF FIGURES

Figure 3.1: Types of Pavements.............................................................................................................9Figure 3.2: Load distribution in different types of pavements................................................................9Figure 3.3: Layers of flexible pavements.............................................................................................10

Figure 5.1: During the CBR Test..........................................................................................................26Figure 5.2: CBR test.............................................................................................................................28Figure 5.3: Thickness and Length gauges.............................................................................................35

Figure 6.1: At the WMM mixing plant.................................................................................................87

Figure 7.1: Compaction of Foamed Bitumen layer...............................................................................90Figure 7.2: Laying of Foamed Bitumen................................................................................................91

Gallery ................................................................................................................................................viii

vii

Chapter-1

Introduction

1.1 General

A road is a thoroughfare (transportation route connecting one location to another),

route, or way on land between two places, which typically has been paved or otherwise

improved to allow travel by some conveyance, including a horse, cart, or motor vehicle.

Roads consist of one, or sometimes two, carriageways each with one or more lanes. Roads

that are available for use by the public may be referred to as public roads or highways.

India has a network of National Highways connecting all the major cities and state

capitals, forming the economic backbone of the country. As of 2010, India has a total of

70,934 km (44,076 mi) of National Highways, of which 200 km (124 mi) are classified

as expressways.

As per the National Highways Authority of India (NHAI), about 65% of freight and

80% passenger traffic is carried by the roads. The National Highways carry about 40% of

total road traffic, though only about 2% of the road network is covered by these roads.

Average growth of the number of vehicles has been around 10.16% per annum over recent

years. Highways have facilitated development along the route and many towns have sprung

up along major highways.

1.2 Background

This particular project deals with the approach roads connecting the 2nd road bridge

across Godavari River in Rajahmundry. Gammon India Private Limited has taken up work

under the Build, Operate and Transfer (BOT) model to construct the 2nd road bridge across

Godavari River. This structure is named as YSR Varadhi. This is an 808-crore rupees mega

project, out of which GIPL will receive a grant of Rs: 207.55-crore from the Central and state

governments. GIPL will maintain this project for 25 years, which includes the construction

period of three years. GIPL has started this project in the year 2009. The 4.2-km-long road

bridge includes 9-km approach road from Diwancheruvu to Katheru and 2-km road in

Kovvuru on the West Godavari side. Once this YSR Varadhi is completed, the distance

between Vijayawada-Rajahmundry-Visakhapatnam will come down by about 30-50 km.

1

1.3 Objectives

The main objective of this project work is to design the pavement thickness by using

the laboratory CBR values of the subgrade soil. There after the project involves the Mix-

Designs of GSB and WMM layers. The next part of the project work is a research on the

substitute for the regular DBM layer. The concept behind this research is to replace the

regular DBM layer with an innovative technology called Foamed Bitumen.

1.4 Scope of work

The design of flexible pavement is carried out by using the laboratory CBR value of

the subgrade soil and the traffic volume data. This task involves all the necessary soil

tests to determine the index properties of soil.

The next part deals with the aggregate tests. The lab tests are conducted on the

aggregates for determining their basic properties. Based on these parameters, the Mix-

Design for GSB and WMM layers are completed.

The final objective of this project work is to find an alternate material to replace the

regular bitumen layer. The regular bitumen is replaced with a new concept called

Foamed Bitumen. This material is cost-effective and more durable.

1.5 Necessity

This project work involves a proposal to implement a new technique in India. The

main reason behind this proposal is the advantages of using foamed bitumen. In India, most of

the pavements need regular maintenance due to the heavy traffic conditions. The use of

foamed bitumen will reduce the need for regular maintenance of roads. Another advantage

with this new technology is that, it can be done by using the recycled aggregates and hence

reducing the wastage.

2

Chapter-2

Literature Review

The first road on which there is some authentic record is that of Assyrian empire

constructed by about 1900 B.C. Only during the period of the Roman Empire, roads were

constructed in large scale and the earliest construction techniques known are of Roman

Roads. Many of these roads were built of stone blocks. Hence Romans are considered to be

the pioneers in road construction.

Pierre Tresaguet (1716-1796) developed an improved method of construction in

France by the year 1964 A.D. The main feature of his proposal was that the thickness of

construction needs to be only in the order of 30 cm. Further due consideration was given by

him to subgrade moisture condition and drainage of surface water.

John Metcalfe, a Scot born in 1717, was the founder of the Institution of Civil

Engineers at London. He built about 180 miles of roads in Yorkshire, England (even though

he was blind). His well-drained roads were built with three layers: large stones; excavated

road material; and a layer of gravel.

The first insight into today's modern pavements can be seen in the pavements of

Thomas Telford (Scottish engineer born 1757). Teleford extended his masonry knowledge

to bridge building. During lean times, he carved grave-stones and other ornamental work

(about 1780). Eventually, Telford became the "Surveyor of Public Works" for the county of

Salop, thus turning his attention more to roads. Telford attempted, where possible, to build

roads on relatively flat grades (no more than a 1 in 30 slope) in order to reduce the number of

horses needed to haul cargo. Telford's pavement section was about 350 to 450 mm (14 to 18

inches) in depth and generally specified three layers. The bottom layer was comprised of large

stones 100 mm (4 inches) wide and 75 to 180 mm (3 to 7 inches) in depth. It is this specific

layer which makes the Telford design unique. On top of this were placed two layers of stones

of 65 mm (2.5 inches) maximum size (about 150 to 250 mm (6 to 9 inches total thickness)

followed by a wearing course of gravel about 40 mm (1.6 inches). It was estimated that this

system would support a load corresponding to about 88 N/mm.

John MacAdam (Scottish engineer born 1756 and sometimes spelled "Macadam")

observed that most of the paved U.K. roads in early the 1800s were composed of rounded

gravel. He knew that angular aggregate over a well-compacted subgrade would perform

substantially better. Macadam pavements introduced the use of angular aggregates. He used a 3

sloped subgrade surface to improve drainage (unlike Telford who used a flat subgrade

surface) on which he placed angular aggregate (hand-broken with a maximum size of 75 mm

(3 inches)) in two layers for a total depth of about 200 mm (8 inches). On top of this, the

wearing course was placed (about 50 mm thick with a maximum aggregate size of 25 mm).

Macadam's reason for the 25 mm (1 inch) maximum aggregate size was to provide a "smooth"

ride for wagon wheels. Thus, the total depth of a typical MacAdam pavement was about 250

mm (10 inches). MacAdam was quoted as saying "no stone larger than will enter a man's

mouth should go into a road" (Gillette, 1906). The largest permissible load for this type of

design has been estimated to be 158 N/mm (900 lb. per in. width). In 1815, Macadam was

appointed "surveyor-general" of the Bristol roads and was then able to use his design on

numerous projects. It proved successful enough that the term "macadamized" became a term

for this type of pavement design and construction. The term "macadam" is also used to

indicate "broken stone" pavement. By 1850, about 2,200 km (1,367 miles) of macadam type

pavements were in use in the urban areas of the UK. MacAdam realized that the layers of

broken stone would eventually become "bound" together by fines generated by traffic. With

the introduction of the rock crusher, large mounds of stone dust and screenings were

generated. The increased use of these fines resulted in the more traditional dense graded base

materials. The first macadam pavement in the U.S. was constructed in Maryland in 1823.

The first tar macadam pavement was placed outside of Nottingham (Lincoln Road)

in 1848. At that time, such pavements were considered suitable only for light traffic (i.e., not

for urban streets). Coal tar, the binder, had been available in the U.K. from about 1800 as a

residue from coal-gas lighting. Possibly this was one of the earlier efforts to recycle waste

materials into a pavement! Soon after the Nottingham project, tar macadam projects were

built in Paris (1854) and Knoxville, Tennessee (1866). In 1871 Washington, D.C. extensively

used a "tar concrete" for road construction. Sulphuric acid was used as a hardening agent and

various materials such as sawdust, ashes, etc. were used in the mixture (Hubbard, 1910).

Over a seven-year period, 630,000 square meters (156 acres) were placed. In part, due to lack

of attention in specifying the tar, most of these streets failed within a few years of

construction. This resulted in tar being discredited, thereby boosting the asphalt industry.

However, some of these tar-bound surface courses in Washington, D.C., survived

substantially longer - about 30 years. For these mixes, the tar binder constituted about 6

percent by weight of the total mix (air voids of about 17 percent). Further, the aggregate was

crushed with about 20 percent passing the 2.00 mm (No. 10) sieve. The wearing course was

4

about 50 mm (2 inches) thick. Hot tar paving products have not been used in the U.S. for

many years.

The first pavements made from true Hot Mix Asphalt (HMA) were called sheet

asphalt pavements. The HMA layers in this pavement were premixed and laid hot. Sheet

asphalt became popular during the mid-1800s with the first ones being built on the Palais

Royal and on the Rue St. Honore in Paris in 1858 (Abraham, 1929). The first such pavement

placed in the U.S. was in Newark, New Jersey, in 1870. Sheet asphalt pavements are no

longer built today.

The final steps towards modern HMA were taken by Frederick J. Warren. In 1901

and 1903, Warren was issued patents for an early HMA paving material and process, which

he called "bitulithic". A typical bitulithic mix contained about 6 percent "bituminous cement"

and graded aggregate proportioned for low air voids. The concept was to produce a mix

which could use a more "fluid" binder than was used for sheet asphalt.

In 1946, two Iowa highway engineers, James W. Johnson and Bert Myers,

conceptualized the slip form paver. In 1949, the Iowa Highway Department constructed the

first slip formed roadway, a 3 m (9 ft.) wide, 150 mm (6 inch) thick section of county road.

By placing two lanes side-by-side, a typical 6 m (18 ft.) wide county road could be built. The

paver attached to a ready mix concrete truck, which would discharge its load into the paver,

then pull the paver forward. In 1955, Quad City Construction Company developed an

improved, self-propelled, track-mounted slip form paver capable of placing 8 m (24 ft.) wide

slabs up to 250 mm (10 inches) thick. In just a few years, several equipment manufacturers

were marketing slip form pavers capable of placing concrete up to four lanes wide.

Invention of Foamed Bitumen: More than forty years ago, Dr Ladis Csanyi at the

Bituminous Research Laboratory of the Engineering Experiment Station, Iowa State

University successfully injected steam into bitumen to create a foaming mass. Csanyi’s

invention was inspired by the abundance of ungraded marginal loess materials in his state of

Iowa, and a shortage of good quality aggregate. Initially, he began experimenting with the

“impact process” patented by a Swiss. Dr Csanyi discovered that, during its metastable life,

the foamed bitumen could be mixed with a variety of soils to improve their properties and

produce a road building material. Since then the foamed bitumen process experienced only

limited application on a global scale, primarily due to the exclusive rights of the patent

holders on the foam nozzles. Dr Csanyi did attempt water as a foaming agent (as well as air,

gases and other foaming agents).

5

In 1968 Mobil of Australia acquired the patent rights for the Csanyi process. Within

two years Mobil had modified the process by replacing the steam with 1% to 2% cold water

that is combined with the hot bitumen in a suitably designed expansion chamber to produce

the foam, which is discharged under pressure (Lee, 1981). A patent for the expansion

chamber/nozzle system was granted to Mobil in Australia in 1971 and was extended to at least

14 countries. This lead to trials of the foamed bitumen process being carried out in some 16

countries in the 1970's.

By 1982, Australia alone had placed some 2.9 million m2 of foamed bitumen mixtures,

generally as a base or sub-base layer. South Africa, New Zealand, Japan, Germany, etc. had

all laid coverage of foamed materials by 1982; whilst by the same date, the USA had

produced hundreds of kilometres of surface layer mixtures with foamed bitumen.

6

Chapter-3

Methodology

3.1 Construction

Road construction requires the creation of a continuous right-of-way, overcoming

geographic obstacles and having grades low enough to permit vehicle or foot travel and

required to meet standards set by law or official guidelines. The process is often begun with

the removal of earth and rock by digging or blasting, construction

of embankments, bridges and tunnels, and removal of vegetation (this may involve

deforestation) and followed by the laying of pavement material. A variety of road building

equipment is employed in road building.

After design, approval, planning, legal and environmental considerations have been

addressed alignment of the road is set out by a surveyor. The Radii and gradient are designed

and staked out to best suit the natural ground levels and minimize the amount of cut and

fill. Great care is taken to preserve reference Benchmarks Roads are designed and built for

primary use by vehicular and pedestrian traffic. Storm drainage and environmental

considerations are a major concern. Erosion and sediment controls are constructed to prevent

detrimental effects. Drainage lines are laid with sealed joints in the road basement with

runoff coefficients and characteristics adequate for the land zoning and storm water system.

Drainage systems must be capable of carrying the ultimate design flow from the upstream

catchment with approval for the outfall from the appropriate authority to a

watercourse, creek, river or the sea for drainage discharge.

A borrow pit (source for obtaining fill, gravel, and rock) and a water source should be

located near or in reasonable distance to the road construction site. Approval from local

authorities may be required to draw water or for working (crushing and screening) of

materials for construction needs. The top soil and vegetation is removed from the borrow pit

and stockpiled for subsequent rehabilitation of the extraction area. Side slopes in the

excavation area not steeper than one vertical to two horizontal for safety reasons.

Old road surfaces, fences, and buildings may need to be removed before construction

can begin. Trees in the road construction area may be marked for retention. These protected

trees should not have the topsoil within the area of the tree's drip line removed and the area

should be kept clear of construction material and equipment. Compensation or replacement

may be required if a protected tree is damaged. Much of the vegetation may be mulched and

put aside for use during reinstatement. The topsoil is usually stripped and stockpiled nearby

for rehabilitation of newly constructed embankments along the road. Stumps and roots are

removed and holes filled as required before the earthwork begins. Final rehabilitation after

road construction is completed will include seeding, planting, watering and other activities to

reinstate the area to be consistent with the untouched surrounding areas.

Processes during earthwork include excavation, removal of material, filling,

compacting, construction and trimming. If rock or other unsuitable material is discovered it is

removed, moisture content is managed and replaced with standard fill compacted to 90%

relative compaction. Generally blasting of rock is discouraged in the road bed. When a

depression must be filled to come up to the road grade the native bed is compacted after the

topsoil has been removed. The fill is made by the "compacted layer method" where a layer of

fill is spread then compacted to specifications; the process is repeated until the desired grade

is reached.

General fill material should be free of organics, meet minimum California bearing

ratio (CBR) results and have a low plasticity index. The lower fill generally comprises sand or

a sand-rich mixture with fine gravel, which acts as an inhibitor to the growth of plants or other

vegetable matter. The compacted fill also serves as lower-stratum drainage. Select second fill

(sieved) should be composed of gravel, decomposed rock or broken rock below a

specified Particle size and be free of large lumps of clay. Sand clay fill may also be used. The

road bed must be "proof rolled" after each layer of fill is compacted. If a roller passes over an

area without creating visible deformation or spring the section is deemed to comply.

The completed road way is finished by paving or left with a gravel or

other natural surface. The type of road surface is dependent on economic factors and expected

usage. Safety improvements like Traffic signs, Crash barriers, Raised pavement markers, and

other forms of Road surface marking are installed.

3.2 Pavement Types

Basically, all hard surfaced pavement types can be categorized into two groups,

Flexible Pavements and

Rigid Pavements

Flexible pavements are those which are surfaced with bituminous (or asphalt)

materials. These types of pavements are called "flexible" since the total pavement structure

"bends" or "deflects" due to traffic loads. A flexible pavement structure is generally

composed of several layers of materials which can accommodate this "flexing".

Figure 3.1: Types of Pavements.

On the other hand, rigid pavements are composed of a PCC surface course. Such

pavements are substantially "stiffer" than flexible pavements due to the high modulus of

elasticity of the PCC material. Further, these pavements can have reinforcing steel, which is

generally used to reduce or eliminate joints.

Flexible pavements generally require some sort of maintenance or rehabilitation every

10 to 15 years. Rigid pavements, on the other hand, can often serve 20 to 40 years with little

or no maintenance or rehabilitation.

Figure 3.2: Load distribution in different types of pavements.

Each of these pavement types distributes load over the subgrade in a different fashion.

Rigid pavement, because of PCC's high elastic modulus (stiffness), tends to distribute the load

over a relatively wide area of subgrade. The concrete slab itself supplies most of a rigid

pavement's structural capacity. Flexible pavement uses more flexible surface course and

distributes loads over a smaller area. It relies on a combination of layers for transmitting load

to the subgrade.

This project completely deals with Flexible Pavements. Almost all the highways and

expressways are flexible. Hence, the analysis in this project only refers to flexible pavements.

The typical cross-section of a flexible pavement consists of several layers. They are as

follows:

Figure 3.3: Layers of flexible pavements.

Original Ground Level (OGL)

Low Embankment

High Embankment

Sub-Grade

Granular Sub-Base (GSB)

Wet Mix Macadam (WMM)

Dense Bitumen Macadam (DBM)

Bitumen Concrete (BC)

3.3 Properties of each layer

3.3.1 Original Ground Level: It is the original ground surface before any work starts.

3.3.2 Low Embankment: Embankment consists of a number of soil layers. It is used to

increase the level of pavement. Low embankment is the one which has a maximum height of

3m. Low embankment should have the following properties:

Minimum compaction of 95%

Minimum Dry Density of 1.55gm/cc

Maximum Free swell index of 50%

Minimum CBR of 10%

Maximum Liquid limit of 40%

Maximum Plasticity index of 18%

3.3.3 High Embankment: High embankment is the one in which height is above 3m. High

embankment should have the following properties:

Minimum compaction of 97%

Minimum Dry Density of 1.63gm/cc

Maximum Free swell index of 50%

Minimum CBR of 10%



3.3.4 Sub-Grade: Sub-grade or Soil Sub-grade is a soil layer above embankment. The

thickness of this layer is 0.25m.

3.3.5 Granular Sub-base: GSB is a layer of mixed aggregates. It consists of dust, 40mm

aggregates and 10mm aggregates. The thickness of this layer is 0.2m. GSB should have the

following requirements:

Minimum Compaction of 98%

Maximum Water Absorption of 2%

Minimum CBR of 30%



Minimum 10% fines of 50KN

3.3.6 Wet Mix Macadam: WMM is a mixture of 40mm, 20mm, 10mm aggregates, dust and

water. It is constructed in 2 layers. The thickness of each layer is about 0.125m. The total

thickness is 0.25m. WMM should have the following properties:



Maximum AIV of 30%



Maximum FI&EI of 30%

3.3.7 Dense Bitumen Macadam: DBM is constructed in 2 layers. The 1st layer should have

minimum bitumen content of 4 to 4.5%. The 2nd layer should have minimum bitumen content

of 4.5 to 5%. The aggregates used for this layer are 40mm, 20mm, 10mm and dust, lime or

cement. Other requirements of DBM are:



Maximum AIV of 27%


Maximum FI&EI of 30%

Chapter-4

Design of Flexible pavement (IRC: 37-2001)

4.1 Traffic Volume data for Rajahmundry-Visakhapatnam in Jan-2012

UP DOWN UP DOWN UP DOWN UP DOWN UP DOWN UP DOWN UP DOWN UP DOWN

UP DOWN UP DOWN UP DOWN UP DOWN UP DOWN UP DOWN

02/01/12, 8 AM to

03/01/12, 8 AMDay 1 30 35 117 154 382 31 165 23 2 3 16 16 22 380 228 286 22 46 35 1744 733 728 7 0 4 0 1763 3446

03/01/12, 8 AM to

04/01/12, 8 AMDay 2 11 25 2 133 8 359 29 133 19 7 14 9 65 464 110 338 24 387 47 1979 365 861 5 3 0 0 699 4698

04/01/12, 8 AM to

05/01/12, 8 AMDay 3 45 24 194 180 388 32 114 14 7 4 16 19 34 490 288 318 376 48 46 1814 698 833 3 4 0 0 2209 3780

05/01/12, 8 AM to

06/01/12, 8 AMDay 4 42 22 153 143 362 353 126 15 7 4 18 7 20 463 324 310 478 26 38 1772 831 776 0 2 0 0 2399 3893

06/01/12, 8 AM to

07/01/12, 8 AMDay 5 22 32 141 146 367 331 133 128 8 6 7 11 11 593 305 317 967 17 56 1870 839 846 0 3 0 0 2856 4300

07/01/12, 8 AM to

08/01/12, 8 AMDay 6 26 46 147 133 364 42 140 11 9 2 18 7 72 615 328 335 56 356 78 2016 746 822 2 1 0 0 1986 4386

08/01/12, 8 AM to

09/01/12, 8 AMDay 7 25 62 33 30 385 32 133 123 2 0 18 7 67 409 222 205 908 47 19 1678 847 749 1 1 0 0 2660 3343

201 246 787 919 2256 1180 840 447 54 26 107 76 291 3414 1805 2109 2831 927 319 12873 5059 5615 18 14 4 0 14572 27846

Avg. 7Days Vehicles 28.71 35.14 112 131 322 169 120 63.86 8 4 15 11 41.6 488 258 301 404 132.4 45.57 1839 723 802 3 2

Average Daily Traffic 63.86 244 491 184 11 26 529 559 537 1885 1525 5 Average Daily Traffic 6060

GRAND TOTAL 42418

Date Day

MAV(more than 3

axles or 10 tyres)

TOTAL

Earth Moving /

Heavy Machinery

TOTALTata ACEGovernment

BusMini BusCar / Jeep / TaxiToll

Exempted Trucks

Light Commercial

Vehicle

3-axleTruck

2-axleTruckPrivate Bus

Toll Exempted

Car Ambulance

Table 4.1: Traffic Volume data for Rajahmundry-Visakhapatnam in Jan-2012

From the above data, the average daily traffic for 7 days is 6060 vehicles per day.

4.2 Computation of design traffic:

The design traffic is considered in terms of the cumulative number of standard axles to be carried during the design life of the road. This can be computed using the following equation:

Where,

N= the number of standard axles in msa.

A= initial traffic in the year of completion of construction in terms of number of commercial vehicles per day.

D= lane distribution factor = 0.4 for four-lane roads (as per IRC: 37-2001).

F= vehicle damage factor.

N= design life in years = 15 years.

r = annual growth rate of commercial vehicles = 8%

The Vehicle damage factor is obtained from the table shown below (Table 1. as per IRC: 37-2001)

Initial traffic volume in terms of number of commercial vehicles per day Vehicle damage factor (VDF)

0-150 1.5

150-1500 3.5

More than 1500 4.5Table 4.2: Vehicle damage factors for different traffic volumes.

As the traffic volume in this case is 6060 commercial vehicles per day, VDF is taken as 4.5.

Now,

Where,

P= Number of commercial vehicles as per last count= 6060 (as per traffic volume data)

X=Number of years between last count and year of completion of construction= 3.

Hence, = 7630.

Therefore,

From calculations, N = 136.1 msa (Say 135 msa).

The CBR value for the soil subgrade is 10%.

Hence use the design chart corresponding to CBR of 10% and traffic of 150msa as shown below:

Table 4.3 IRC design Chart based on CBR value of 10%

The chart contains the data for 100 and 150 msa of traffic. We can get the required data for 135 msa, by using the interpolation formula as shown here:

Where,

x0, x1 = 100, 150.

y0, y1 = 630, 650.

x = 135

Therefore,

Hence, Total pavement thickness = 645mm.

Let us provide a total pavement thickness of 650mm.

From the graph shown in design chart (corresponding to 150 msa), the following details of each layer can be obtained:

Granular Sub Base (GSB) = 200mm.

Wet Mix Macadam (WMM) = 250mm.

Dense Bitumen Macadam (DBM) = 150mm.

Base Course (BC) = 50mm.

Total Pavement Thickness = 650mm.

Note: The pavement design mentioned here is based on the basic parameters and values at the

construction site. It is designed according to the IRC method and is done as a part of this

project report. This design is not a resemblance of the original pavement which is under

construction by Gammon India Ltd.

Chapter-5

Tests on pavement materials

Various tests for soil and aggregates are conducted in the laboratory to determine the

properties of the materials. The next part of this project explains the procedures and

calculations involved for these lab tests. The values obtained for each differ layer is presented

after this part.

5.1 Tests on soil

5.1.1 Introduction

Soil is very essential highway material because of the under mentioned reasons:

(i) Soil subgrade is part of the pavement structure; further the design and behavior of

pavement, especially the flexible pavements, depend to a great extent on the

subgrade soil.

(ii) Soil is one of the principal materials of construction in soil embankments and in

stabilized soil base and sub-base courses.

In view of the wide diversity in soil type, it is desirable to classify the subgrade soil

into groups possessing similar physical properties. Many methods have been in use for this

purpose. Soils are normally classified on the basis of simple laboratory tests such as grain size

analysis and consistency tests.

Soil compaction is important phenomenon in highway construction as compacted

subgrade improves the load supporting ability of pavement; in turn resulting in decreased

pavement thickness requirement. Compaction of earth embankments would result in

decreased settlement. Thus the behavior of soil sub-grade material could be considerably

improved by adequate compaction under controlled conditions. The laboratory compaction

test results are useful in specifying the optimum moisture content at which a soil should be

compacted and the dry density that should be aimed at the construction site. The in-situ

density of prepared subgrade as well as other pavement layers has to be determined by a field

density test, for checking the compaction requirements and as a field control test for

compaction.

There are a number of tests for measuring soil strength; some of them give the strength

parameters of the soil, other methods are empirical and give only arbitrary strength values.

The types of the strength tests may be classified as shear test, bearing and penetration tests.

The triaxial test results are useful to find the strength parameters, viz; cohesion and angle of

internal friction and modulus deformation of soils. The California Bearing Ratio test is

essentially a penetration test which is carried out either in the laboratory or in the field. This

test is suitable for the evaluation of strength of soil and aggregates. The method has an

important place among highway material testing programme, as it has been extensively

correlated with flexible pavement design and performance. North Dakota Cone Test is another

penetration test which may also be carried out either in the laboratory or on in-situ soil in the

field, but its use is restricted to fine grained soils free from coarse particles. Plate bearing test

is carried out either on subgrade to find the modulus of subgrade reaction or on a pavement

component layer for pavement evaluation.

There are several soils which are unsuitable as highway material, since they cannot be

used as such in the base course, sub-base or the subgrade. The strength and durability

characteristics of these soils can be improved to the desired extent by adopting a stabilization

technique. One of the widely used methods of stabilization is soil-cement which is applicable

to a fairly wide range of soil types. The cement stabilized soil can be used in sub-base and

base course layers of pavements.

5.1.2 Free Swell Index (IS 2720 part-40)

Free swell index of soil is determined as per IS: 2720 (Part 40). Free swell or

differential free swell, also termed as free swell index, and is the increase in volume of soil

without any external constraint when subjected to submergence in water.

5.1.3 Grain Size Analysis (IS 2720 part-4)

Most of the methods for soil identification and classification are based on certain

physical properties of the soils. The commonly used properties for the classification are the

grain size distribution, liquid limit and plasticity index. These properties have also been used

in empirical design methods for flexible pavements and in deciding the suitability of subgrade

soils.

Grain size analysis also known as mechanical analysis of soils is the determination of

the percent of individual grain sizes present in the sample. The results of the test are of great

value in soil classification. In mechanical stabilization of soil and for designing soil-aggregate

mixtures the results of gradation tests are used. Correlations have also been made between the

grain size distribution of soil and the general soil behavior as a subgrade material and the

performance such as susceptibility to frost action, pumping of rigid pavements etc. Also

permeability characteristics, bearing capacity and some other properties, are approximately

estimated based on grain size distribution of the soil.

The soil is generally divided into four parts based on the particle size. The fraction of

soil which is larger than 2.00 mm size is called gravel and that between 2.00 and 0.06 mm is

sand, between 0.06 and 0.002 mm is silt and that which is smaller than 0.002 mm size is clay.

Two types of sieves are available, one type with square perforations on plates to sieve coarse

aggregates and gravel, the other type being mesh sieves made of woven wire mesh to sieve

finer particles such as fine aggregates and soil fraction consisting of sand silt and clay.

However the sieve opening of the smallest mesh sieve commonly available is about 0.075

mm, which is commonly known as 200-mesh sieve or sieve no. 200 as per the British and

American specifications. Therefore all soil particles consisting of silt and clay which are

smaller than 0.06 mm size will pass through the fine mesh sieve with 0.075 mm opening.

Therefore the grain size analysis of the coarser fraction

of soil is carried out using sieves and that of finer

fraction passing 0.075 mm sieve is carried out using

the principle of sedimentation in water.

The mechanical analysis consists of two parts:

a) The determination of the amount and

proportion of coarse material by the use of

sieves; and

b) The analysis for the line grained fraction by

sedimentation method.

The sieve analysis is a simple test consisting of

sieving a measured quantity of material through

successively smaller sieves. The weight retained on

each sieve is expressed as a percentage of the total

sample. The sedimentation principle has been used for

finding the grain size distribution of fine soil fraction;

two methods are commonly used viz: Pipette method

and the Hydrometer method. In this project only the

sieve analysis has been used.

The grain size distribution of soil particles of

size greater than 63 micron is determined by sieving

the soil on a set of sieves 01 decreasing sieve opening placed one below the other and

separating out the different size ranges.

Two methods of sieve analysis are as follows:

a) Wet sieving applicable to all soils and

b) Dry sieving applicable only to soils which have negligible proportion of clay and silt.

The soil received from the field is divided into two parts: one, the fraction retained on

2 mm sieve and the other passing 2 mm sieve. The sieve analysis also may be carried out

separately for these two fractions. The fraction retained on 2 mm sieve may be subjected to

dry sieving using bigger sieves and that passing 2 mm sieve may be subjected to wet sieving,

however if this fraction consists of single grained soil with negligible fines passing 0.075 mm

size, dry sieving may be carried out.

Application of Grain Size Analysis

(a) Soil classification

In most of the soil classification systems the percentage of material passing 200-mesh

and 40-mesh sieve (75 and 420 microns aperture) have been considered from the grain size

analysis, though some classification systems use percentage of silt and clay present for

classifying the soils. Hence ordinarily the sieve analysis (dry or wet) will be quite sufficient

along with tests for consistency limits, for identifying and classifying soils.

The two widely accepted soil classification systems for highway engineering purposes are

(i) The Highway Research Board (HRB) classification, also known as American Association

of State

Highway Officials (AASHO) classification or revised Public Roads Administration (PRA)

classification and

(ii) The Unified classification system, also known as revised Casagrande classification. Both

these systems of classification have based their classification on the grain size analysis by

sieve analysis, the liquid limit and plasticity index of the soils.

However for knowing the grain size distribution of soils finer than 75 or 63 micron

size and to determine the percentage of silt and clay, the sedimentation methods namely the

pipette or hydrometer method of test may be adopted.

(b) Grain size distribution

The grain size distribution curve gives the exact idea regarding the gradation of the

soils. It is possible to identify whether a soil is well graded, uniformly graded, or poorly

graded. Uniformity coefficient is also useful to indicate the gradation.

5.1.4 Consistency Limits and Indices (IS 2720 part-5)

The physical properties of fine grained soils, especially of clay differ much at different

water contents. Clay may he almost in liquid state, or it may show plastic behavior or may be

very stiff depending on the moisture content. Plasticity is a property of outstanding

importance for clayey soils, which may be explained as the ability to undergo changes in

shape without rupture.

Atterberg in 1911 proposed a series of tests mostly empirical for the determination of

the consistency and plastic properties of fine soils. These are now known as Atterberg limits

and indices.

Liquid Limit it may he defined as the minimum water content at which the soil will

flow under the application of a very small shearing force. The liquid limit is usually

determined in the laboratory using a mechanical device. An alternate method using a cone

penetrometer is also sometimes used for determining the liquid limit of soils.

Plastic Limit may be defined in general terms, as the minimum moisture content at

which the soil remains in a plastic state. The lower limit is arbitrarily defined and determined

in the laboratory by a prescribed test procedure. Plasticity Index (P.I.) is defined as the

numerical difference between the liquid and plastic limits. P.I. thus indicates the range of

moisture content over which the soil is in a plastic condition.

Shrinkage Limit is the maximum moisture content at which further reduction in water

content does not cause reduction in volume. It is the minimum water content that can occur in

clayey soil sample which is completely saturated.

Consistency limits and the plasticity index vary for different soil types. Hence these

properties are generally used in the identification and classification of soils.

Liquid Limit Test

Liquid limit is the moisture content at which 25 blows in standard liquid limit

apparatus will just close a groove of standardized dimensions cut in the sample by the

grooving tool by a specified amount.

The above graph represents the liquid limit at 25 blows of a sample.

Plastic Limit Test

Plastic limit in the moisture content at which it soil when rolled into thread of smallest

diameter possible starts crumbling and has a diameter of 3 mm.

5.1.5 Compaction Test (IS 2720 part-8)

Compaction of soil is a mechanical process by which the soil particles are constrained

to be packed more closely together by reducing the air voids; Soil compaction causes decrease

in air voids and consequently an increase in dry density. This may result in increase in

shearing strength. The possibility of future settlement or compressibility decreases and also

the tendency for subsequent changes in moisture content decreases. Degree of compaction is

usually measured quantitatively by dry density.

Increase in dry density of soil due to compaction mainly depends on two factors-(i) the

compacting moisture content and (ii) the amount of compaction. For practically all soils it is

found that with increase in the compaction moisture content; the dry density first increases

and then decreases compacted by any method. This indicates that under a given compactive

effort every soil has optimum moisture content (OMC) at which the soil attains maximum dry

density. This fact was first recorded by R. R. Proctor in 1933.

For a soil at a given moisture content, increasing amounts of compaction result in

closer packing of soil particles and an increase in dry density, until the volume of air voids is

so decreased that further compaction produces no substantial change in the volume. It has

been found that in all soils, with all methods of compaction, increase in compacting energy

applied per unit weight of soil result in an increase in maximum dry density and a decrease in

OMC. In the field, compaction may be carried out by

(i) applying pressure on soil layers by means of rollers

(ii) ramming

(iii) vibration

(iv) Watering depending upon the soil type and nature of the project.

In the laboratory various types of compacting equipment and test methods have been

developed for determining the moisture density relationships of soils. These tests may be

classified as:

(i) Static compaction test, an example of a test method of this type is California static

load compaction developed at California Division of Highway.

(ii) The dynamic compaction tests which are commonly adopted tests in the laboratory

the test methods which are often followed are (a) Proctor Test, later standardized by different

agencies and known as BS compaction IS light compaction and Standard AASHO tests (b)

modified AASHO tests also standardized by ISI and known as IS heavy compaction (c) the

indirect application of impact through a piston as in the Direct tests or Iowa Bearing value

apparatus.

(iii) Kneading compactor in which the compaction is achieved by applying a gradually

increasing stress through rounded end of a piston and releasing it gradually after retaining it

for a small interval of time. This is considered to simulate the type of compacting process as

rolling in the field. It has been found that the stress-strain behavior of a compacted soil by

different methods of compaction is likely to vary even if the compacting moisture content and

dry density values are the same.

The test is divided into two parts (i) light compaction which is similar to the BS or

Standard AASHO compaction test and (ii) heavy compaction which is similar to the modified

AASO compaction test. These two have been standardized by the ISI (I.S. 2720 parts VII and

VIII).

The above graph shows the Optimum moisture content and Maximum dry density.

Applications of Compaction Test

From the compaction test, the maximum dry density and optimum moisture content of

the soil is found for the selected type and amount of compaction. These results have various

uses.

(a) The OMC of the soil indicates the particular moisture content at which the soil should

be compacted to achieve maximum dry density. If the compacting effort applied is

less, the OMC increases and the value can again be found experimentally or estimated.

(b) In field compaction, the compacting moisture content is first controlled at OMC and

the adequacy of rolling or compaction is controlled by checking the dry density

achieved and comparing with the maximum dry density achieved in the laboratory.

Thus compaction test results (OMC and maximum dry density) are used in the field

control test in compaction projects.

Compaction, in general is considered most useful in the preparation of subgrade and

other pavement layers and in construction of embankments in order to increase the stability

and to decrease the settlement. There is also a soil classification method based on the

maximum dry density in the standard (Proctor) compaction test, the lower values indicating

weaker soils. According to the method suggested by K.R.Woods, soils with maximum values

of dry density (in g/cm3) greater than 2.1 are excellent, 1.9 to 2.1 are good, 1.75 to 1.90 are

fair, 1.60 to 1.75 are poor and those less than 1.60 are very poor.

5.1.6 Field Density Test by Sand Replacement Method (IS 2720 part-28)

The dry density of compacted soil or pavement material is a common measure of the

amount of the compaction achieved during the construction. Knowing the field density and

field moisture content, the dry density is calculated. Therefore, field density or

in-situ density test is of importance as a field control test for the compaction of

soil or any other pavement layer. The determination of field density of natural

bed or soil has also various other applications in civil engineering.

There are several methods for the determination of field density of

soils such as core cutter method, sand replacement method, rubber balloon method, heavy oil

method, etc. One of the common methods of determining field density of fine grained soils is

core cutter method; but this method has a major limitation in the case of soils containing

coarse grained particles such as gravel, stones and aggregates. Under such circumstances,

field density test by sand replacement method is advantageous as the presence of coarse

grained particles will adversely affect the test results and also the method is quite simple.

The basic principle of sand replacement method is to measure the in-situ volume of

whole from which the material was excavated from the weight of sand with known density

filling in the hole. The in-situ density of material is given by the weight of the excavated

material divided by the in-situ volume.

Applications of the field density test

Determination of field density or in-place density, moisture content and dry density of

a compacted layer of soil or pavement layer arc often used to check the amount of compaction

attained in the field and for quality control tests in field compaction.

The determination of in-situ density of soil is useful in calculating the over burden

pressure of a soil deposit, calculation of bearing capacity, analysis of stability slopes and

foundations and in several other problems. The dry density of a compacted soil mass is also

used for assessing soil type and its stability.

The sand replacement method of field density test can be applied for any type of soil

and pavement materials, whereas the core cutter method cannot be used it coarse particles are

present in the compacted layer.

5.1.7 California Bearing Ratio Test (IS 2720 part-16)

The California Bearing Ratio (CBR) test was developed by the California Division of

Highway as a method of classifying and evaluating soil-subgrade and base course materials

for flexible pavements. Just after World War II, the U.S. Corps of Engineers adopted the CBR

test for use in designing base course for airfield pavements. The test is empirical and results

cannot be related accurately with any fundamental property of the material. The method of

test has been standardized by the ISI also.

The CBR is a measure of resistance of a material to penetration of standard plunger

under controlled density and moisture conditions. The test procedure should be strictly

adhered if high degree of reproducibility is desired. The CBR test may be conducted in re-

moulded or undisturbed specimen in the laboratory. U.S. Corps of Engineers have also

recommended a test procedure for in-situ test. Many methods exist today which utilize mainly

CBR test values for designing pavement structure. The test is simple and has been extensively

investigated for field correlations of flexible pavement thickness requirement.

Briefly, the test consists of causing a cylindrical plunger of 50 mm diameter to

penetrate a pavement component material at 1.25 mm/minute. The loads, for 2.5 mm and 5

mm are recorded. This load is expressed as a percentage of standard load value at a respective

deformation level to obtain CBR value. The standard load values were obtained from the

average of a large number of tests on different crushed stones and are given in table below.

Penetration, mm Standard Load, KgUnit Standard Load,

Kg/cm3

2.5

5.0

7.5

10.0

12.5

1370

2055

2630

3180

3600

70

105

134

162

183

Table 5.1: Standard load values.

Figure 5.1: During the CBR Test

The table below shows the specifications of light compaction and heavy compaction:

Type of compactionNumber of

layers

Weight of

hammer, KgFall, cm

Number of

blows

Light Compaction

Heavy Compaction

3

5

2.6

4.89

31

45

56

56

Table 5.2: Types of compaction.

Here is an example of CBR graphs. The graphs below are obtained for subgrade soil

of 10% CBR.

Figure 5.2: CBR test

Now the CBR value is calculated by using the data from the above graphs.

The CBR data for different blows is as follows:

Number of blows Dry Density (gm/cc) CBR%

10 1.760 4.49

30 1.871 9.93

65 1.994 13.14

The MDD of the soil is 1.976 gm/cc. If the required compaction is 97%, then the required

MDD is obtained as shown here:

Now the CBR is obtained at 1.917 dry density. The graph is shown below:

Applications of CBR:

Based on the extensive CBR test data collected; empirical design charts were

developed by the California State Highway Department, correlating the CBR value and the

flexible pavement thickness requirement.

5.2 Tests on Road Aggregates

5.2.1 Introduction

Aggregate forms the major part of the pavement structure and it is the prime material

used in pavement construction. Aggregates have to primarily bear load stresses occurring on

the roads and runways and have to resist water due to abrasive action of traffic. Aggregates

are used in construction of pavements using cement concrete, bituminous construction

methods and in water bound macadam. Aggregates often serve as granular base course

underlying the superior pavements. Thus the properties of the aggregates are of considerable

significance to the highway engineers.

Aggregates which are used in the surface course have to withstand the high magnitude

of load stresses and wear and tear due to abrasion. Such aggregates should possess sufficiently

high strength of resistance to crushing. These aggregates further need to be hard enough to

resist the wear due to abrasive action of traffic.

The aggregates in the pavements are also subjected to impact due to the moving

Wheel loads. Severe impact like hammering is quite common when heavily loaded steel tyre

vehicles move on water bound macadam roads where stones protrude out especially in the

monsoon. Jumping of the steel tyre wheels from one stone to another at different levels

causes’ severe impact on the stones. The resistance to impact or toughness is hence another

desirable property of aggregates. The stones should retain the strength and hardness and

should not disintegrate under adverse weather conditions including alternate wet-dry and

freeze-thaw cycles, or in other words the stones should have enough durability.

The specific gravity of stones is considered to be a measure for finding the suitability

and strength characteristics of aggregates. Higher the specific gravity better is the road stone.

The presence of air voids or pores in stones also may indicate the suitability and strength

characteristics of the stones. More the voids, the lesser are the specific gravity and the

strength of such stones will also be lower. In bituminous road construction to some extent the

presence of pores in aggregates is considered to be good for proper binding.

The size of the aggregate is qualified by the size of square sieve opening through

which the same may pass, and not by the shape. All aggregates which happen to fall in a

particular size range may not have the same strength and durability when compared with

cubical, angular or rounded particles of the same stone. Too flaky and elongated aggregates

should he avoided as far as possible as they can be crushed under the roller and traffic loads.

Rounded aggregate may be preferred in cement concrete mix due to better workability for the

same proportion or cement Paste and same water-cement ratio, whereas rounded particles are

not preferred in granular base course and water bound macadam construction as the stability

due to interlocking is lesser in these aggregates; in such construction angular particles are

preferred.

Heavy moving loads on the surface of flexible pavements may cause some temporary

deformation of the pavement layers resulting in possible relative movement and mutual

rubbing of aggregate particles. This can cause wear on the Points of contacts of the aggregate

in the granular base course of flexible pavements. The mutual rubbing action of the

aggregates is termed as attrition and the resistance to wear due to attrition was earlier assessed

by an attrition test. However this test was dropped later-on and an aggregate abrasion test

alone is now considered necessary to assess the hardness of coarse aggregates.

Affinity of aggregates to bituminous binders is an important property only for the

bituminous pavements. If the bituminous binder does not have affinity to the aggregates, then

stripping is likely to occur.

The desirable properties or the aggregates may be summarised as follows

i. Resistance to crushing or strength

ii. Resistance to abrasion or hardness

iii. Resistance to impact or toughness

iv. Good shape factors to avoid too flaky and elongated particles of course

aggregates

v. Resistance to weathering or soundness

vi. Good adhesion with bituminous materials in presence of water or less

stripping.

The required properties of aggregates depend on type of pavement construction, traffic

and climatic conditions. All the above mentioned properties need not necessarily be possessed

by aggregates for a particular construction. Engineer-in-charge will use his discretion in

deciding the relative importance of these properties.

Tests which are generally carried out for judging the suitability of stone aggregates are

listed below

Strength

Aggregate crushing test

Hardness

Los Angeles abrasion test

Deval abrasion test

Dorry abrasion test

Toughness

1. Aggregate impact test

Durability

2. Soundness test-accelerated durability test

Shape factors

3. Shape test

Specific gravity and Porosity

4. Specific gravity test and water absorption test

5.2.2 Aggregate Impact Test (IS 2386 part-4)

Toughness is the property of a material to resist impact. Due to traffic loads, the road

stones are subjected to the pounding action or impact and there is possibility of stones

breaking into smaller pieces. The road stones should therefore be tough enough to resist

fracture under impact. A test designed to evaluate the toughness of stones i.e., the resistance

of the stones to fracture under repeated impacts may be called an impact test for road stones.

Impact test may either be carried out on cylindrical stone specimens as in Page Impact

test or on stone aggregates as in Aggregate Impact test. The Page Impact test is not carried out

now-a-days and has also been omitted from the revised British Standards for testing mineral

aggregates. The Aggregate Impact test has been standardised by the British Standard

Institution and the Indian Standard Institution.

The aggregate impact value indicates a relative measure of the resistance of aggregate

to a sudden shock or an impact, which in some aggregates differs from its resistance to a slow

compressive load. The method of test covers the procedure for determining the aggregate

impact value of coarse aggregates.

Aggregate Impact values Property

<10% Exceptionally strong

10 to 20% Strong

20 to 30% Satisfactory for road surfacing

>35% Weak for road surfacing

Table 5.3: Aggregate Impact Values

Applications of Aggregate Impact Value

The aggregate impact test is considered to be an important test to assess the suitability

of aggregates as regards the toughness for use in pavement construction. It has been found

that for majority of aggregates, the aggregate crushing and aggregate impact values are

numerically similar within close limits. But in the case of fine grained highly Siliceous

aggregate which are less resistant to impact than to crushing the aggregate impact values are

higher (on the average, by about 5) than the aggregate crushing values.

For deciding the suitability of soft aggregates in base course construction, this test has

been commonly used. A modified impact test is also often carried out in the case of soft

aggregates to find the wet impact value after soaking the test sample

Condition of sampleMaximum aggregate impact value, percent

Sub-base and base Surface course

Dry

Wet

50

60

32

39

Table 5.4: Maximum Limits for Aggregate Impact Value.

82

5.2.3 Specific Gravity and Water Absorption Tests (IS 2386 part-3)

The specific gravity of an aggregate is considered to be a measure of strength or

quality of the material. Stones having low specific gravity are generally weaker than those

with higher specific gravity values. The specific gravity test helps in identification of stone.

Water absorption gives an idea of strength of rock. Stones having more water

absorption are more porous in nature and are generally considered unsuitable unless they are

found to be acceptable based on strength, impact and hardness tests.

Application of Specific Gravity and Water Absorption Test

The specific gravity of aggregates normally used in road construction ranges from

about 2.5 to 3.0 with an average value of about 2.68. Though high specific gravity of an

aggregate is considered as an indication of high strength, it is not possible to judge the

suitability of a sample of road aggregate without finding the mechanical properties such as

aggregate crushing, impact and abrasion values.

Water absorption of an aggregate is accepted as measure of its porosity. Some times

this value is even considered as a measure of its resistance to frost action, though this has not

yet been confirmed by adequate research.

Water absorption value ranges from 0.1 to about 2.0 percent for aggregate normally

used in road surfacing. Stones with water absorption upto 4.0 percent have been used in base

courses. Generally a value of less than 0.6 percent is considered desirable for surface course

through slightly higher values are allowed in bituminous constructions. Indian Road Congress

has specified the maximum water absorption value as 10 percent for aggregates used in

bituminous surface dressing.

5.2.4 Shape Test (IS 2386 part-1)

The particle shape of aggregates is determined by the percentages of flaky and

elongated particles contained in it. In the case of gravel it is determined by its angularity

number. For base course and construction of bituminous and cement concrete types, the

presence of flaky and elongated particles are considered undesirable as they may cause

inherent weakness with possibilities of breaking down under heavy loads. Rounded

aggregates are preferred in cement concrete road construction as the workability of concrete

improves. Angular shape of particles is desirable for granular base course due to increased

stability derived from the better interlocking. When the shape of aggregates deviates more

from the spherical shape, as in the case of angular, flaky and elongated aggregate, the void

content in an aggregate of any specified size increases and hence the grain size distribution of

a graded aggregate has to be suitably altered in order to obtain minimum voids in the dry mix

or the highest dry density. The angularity number denotes the void content of single sized

aggregates in excess of that obtained with spherical aggregates of the same size. Thus

angularity number has considerable importance in the gradation requirements of various types

of mixes such as bituminous concrete and soil-aggregate mixes.

Thus evaluation of shape of the particles, particularly with reference to flakiness,

elongation and angularity is necessary.

Flakiness Index

The flakiness index of aggregates is the percentages by weight of particles whose least

dimension (thickness) is less than three-fifths (0.6) of their mean dimension. The test is not

applicable to sizes smaller than 6.3 mm.

Figure 5.3: Thickness and Length gauges.

Elongation Index

The elongation index of an aggregate is the percentage by weight of particles whose

greatest dimension (length) is greater than one and four fifth times (1.8 times) their mean

dimension. The elongation test is not applicable to sizes smaller than 6.3 mm.

Size of aggregate (a) Thickness gauge

(0.6 times the mean

sieve), mm

(b) Length gauge

(1.8 times the mean

sieve), mmPassing through IS

sieve, mm

Retained on IS

sieve, mm

1 2 3 4

63.0

50.0

40.0

31.5

25.0

20.0

16.0

12.5

10.0

50.0

40.0

25.0

25.0

20.0

16.0

12.5

10.0

6.3

33.90

27.00

19.50

16.95

13.50

10.80

8.55

6.75

4.89

--

81.0

58.5

--

40.5

32.4

25.6

20.2

14.7

Table 5.5: Specifications for Thickness and Length gauges.

Applications of Shape Tests

In the pavement construction flaky and elongated particles are to be avoided,

particularly in surface course. If flaky and elongated aggregates are present in appreciable

proportions, the strength of the pavement layer would be adversely affected due to possibility

of breaking down under loads. In cement in strength in cement concrete depends concrete the

workability is also reduced. However, the reduction in strength in cement depends on the

cement content and water-cement ratio.

Indian Road Congress recommended the maximum allowable limits of flakiness index

values for various types of construction, as given in Table below.

Types of pavement constructionMaximum limits of

Flakiness Index, %

1. Bituminous Carpet

2. Bituminous/ Asphaltic concrete

Bituminous penetration macadam

Bituminous surface dressing (single costs, two coats and

precoated)

Built-up spray grout

3. Bituminous macadam

Water bound macadam, base and surfacing courses

30

25

15

Table 5.6: Maximum limits for Flakiness Index.

Through elongated shape of the aggregates also effects the compaction and the

construction of pavements, there are no specified limits of elongation index values as in the

case of flakiness index for different methods of pavement construction.

Chapter-6

Test Results

6.1 Low Embankment

6.1.1 Grain Size Analysis:

Sample Number : 1 Use : EmbankmentType of material : Soil Weight : 1000gms

Sieve sizeWeight retained

g.

Cumulative weight

retained g.% Retained % Passing Remarks

19 mm 0 0 0 100 4.75 mm 101 101 10.1 89.9

2 mm 134 235 23.56 76.44 425 microns 81 316 31.69 68.31 75 microns 382 698 69.8 30.3

Gravel (4.75 mm retaining) : 10.1 %Sand (4.75 mm passing & 75 micron retaining) : 59.7%

Silt & Clay (75 micron passing) : 30.2%



g.

Cumulative weight


19 mm 0 0 0 100 4.75 mm 107 107 10.7 89.3


Gravel (4.75 mm retaining) : 10.7%Sand (4.75 mm passing & 75 micron retaining) : 60.5%


Grain Size Analysis (Continued):



g.

Cumulative weight


19 mm 0 0 0 100 4.75 mm 95 95 9.5 90.5






g.

Cumulative weight


19 mm 0 0 0 100 4.75 mm 85 85 8.5 91.5







g.

Cumulative weight


19 mm 0 0 0 100 4.75 mm 109 109 10.9 89.1




6.1.2 Atterberg Limits:

Type of Material Soil Sampled No 1

Proposed Use Embankment

Liquid Limit Plastic LimitDetermination No. 1 2 3 4 1 2

Container No. 15 16 17 18 19 20

Empty weight container W1 6.4 6.8 6.9 6.6 8.8 8.4

Wt. of container and wet soil W2 27.1 27.7 27.8 26.9 13.5 13.2

Wt. of container and dry soil W3 21.72 22.37 22.63 21.89 12.76 12.43

Wt. of moisture W4=W2-W3 5.38 5.33 5.17 4.51 0.74 0.77

Wt. of dry soil W5=W3-W1 15.32 15.57 15.73 15.39 3.96 4.03

Moisture Content w = 100*W4/W5

%35.11 34.23 32.86 31.80 18.68 19.10

No. of Blows 19 22 26 32 Average = 18.89

Average = 33.36 Plasticity Index = 14.47

Atterberg Limits (Continued):




Container No. 21 22 23 24 25 26





Wt. of dry soil W5=W3-W1 15.71 15.83 15.66 15.9 6.32 6.22


%34.30 33.29 32.18 31.44 18.67 19.97






Container No. 3 4 5 6 7 8





Wt. of dry soil W5=W3-W1 15.12 14.24 14.98 14.67 4.3 4.7


% 34.25 33.42 32.17 31.51 18.60 19.14







Container No. 5 8 11 20 30 34





Wt. of dry soil W5=W3-W1 23.47 22.97 27.91 26.17 14.03 11.48


% 33.28 32.39 31.28 30.01 17.03 18.64






Container No. 13 19 21 25 27 34





Wt. of dry soil W5=W3-W1 22.43 27.66 24.84 21.33 13.30 10.18


% 36.49 35.65 33.82 32.77 18.95 20.83



6.1.3 Modified Proctor:

Type of Material Soil Sample Number 1


Mould No : 3wt. of Mould, W1 (g) :2320 Volume of mould, V (cc) : 2250

Trial No : I II III IV V VI

Wt. of water 240 360 480 600 720 840

Wt. of wet soil + mould, W2 10457 10721 10998 11076 10870 10722

Wt. of wet soil, W3=(W2-W1) 4137 4401 4678 4756 4550 4402

Wet density, Yb = W3/V 1.839 1.956 2.079 2.114 2.022 1.956

Container No. 2 7 10 29 32 35

Wt. of container,W5 6.4 8.8 6.8 7.2 8.8 7.4

Wt. of wet soil + cont., W6 31.82 44.24 34.24 38.04 43.82 40.02

Wt. of dry soil + cont.,W7 30.75 42.17 32.30 35.43 40.23 36.11

Wt. of water, W8=(W6-W7) (g) 1.07 2.07 1.94 2.61 3.59 3.91

Wt. of dry soil, W9=(W7-W5) (g) 24.05 33.37 25.5 28.23 31.43 28.71

Water content w =W8/W9 % 4.41 6.20 7.62 9.24 11.42 13.61

Dry density Yd = 100x (Yb/100+w) (g/cc) 1.761 1.842 1.932 1.935 1.815 1.722

MDD: 1.945 gm/cc OMC: 8.41 %

Type of Material Soil Sample Number 2Proposed Use Embankment



Wt. of water 240 360 480 600 720 840


Wt. of wet soil, W3=(W2-W1) 4124 4383 4595 4694 4523 4401

Wet density, Yb = W3/V 1.833 1.949 2.042 2.086 2.010 1.956

Container No. 7 10 21 28 32 35

Wt. of container,W5 8.8 6.8 7.0 8.2 8.8 7.4



Wt. of water, W8=(W6-W7) (g) 1.49 1.35 1.76 2.69 4.00 3.45




MDD: 1.921gm/cc OMC: 8.34%

Modified Proctor (Continued):




Wt. of water 240 360 480 600 720 840


Wt. of wet soil, W3=(W2-W1) 3988 4296 4599 4723 4456 4317

Wet density, Yb = W3/V 1.773 1.909 2.044 2.099 1.908 1.919

Container No. 19 22 26 28 33 35

Wt. of container,W5 8.8 7.2 7.4 8.2 9.8 7.4



Wt. of water, W8=(W6-W7) (g) 1.47 1.36 1.91 2.88 3.96 3.56




MDD: 1.912 gm/cc OMC: 9.16%




Wt. of water 240 360 480 600 720 840


Wt. of wet soil, W3=(W2-W1) 4181 4400 4652 4742 4552 4429

Wet density, Yb = W3/V 1.858 1.956 2.067 2.108 2.023 1.969

Container No. 22 26 28 33 35 1

Wt. of container,W5 7.2 7.4 8.2 9.8 7.4 9.0



Wt. of water, W8=(W6-W7) (g) 1.25 1.81 2.57 3.39 3.42 4.66




MDD: 1.934 gm/cc OMC: 8.46%


Type of Material Soil Sample Number 5 Proposed Use Embankment



Wt. of water 240 360 480 600 720 840


Wt. of wet soil, W3=(W2-W1) 4057 4846 4662 4777 4502 4353

Wet density, Yb = W3/V 1.803 1.932 2.072 2.123 2.000 1.975

Container No. 20 23 27 32 35 2

Wt. of container,W5 8.4 7.8 7.2 8.8 7.4 6.4



Wt. of water, W8=(W6-W7) (g) 1.26 1.72 2.05 2.86 2.76 2.92




MDD: 1.935 gm/cc OMC: 9.38%

6.2 High Embankment:


Sample Number: 1 Use : High EmbankmentType of material : Soil Weight : 1000 g


g.

Cumulative weight


19 mm 0 0 0 100

4.75 mm 97 97 9.7 90.3

2 mm 212 309 30.9 69.10

425 microns 110 419 41.95 58.05

75 microns 330 749 74.95 25.05





g.

Cumulative weight


19 mm 0 0 0 100

4.75 mm 88 88 8.8 91.2

2 mm 120 208 20.85 79.15

425 microns 111 319 31.96 68.94

75 microns 420 739 73.9 26.1






g.

Cumulative weight


19 mm 0 0 0 100

4.75 mm 75 75 7.5 92.5

2 mm 163 238 23.78 76.22

425 microns 71 309 30.96 69.04

75 microns 461 770 77.0 23.0





g.

Cumulative weight


19 mm 0 0 0 100

4.75 mm 95 95 9.5 90.5

2 mm 134 229 22.91 77.01

425 microns 120 349 34.96 65.04

75 microns 339 738 73.77 26.23




Sample Number: 5 Use : High Embankment

Type of material : Soil Weight : 1000 g


g.

Cumulative weight


19 mm 0 0 0 100

4.75 mm 84 84 8.4 91.6

2 mm 152 236 23.59 76.41

425 microns 73 309 30.95 69.05

75 microns 470 779 77.89 22.02




Type of Material Soil Sampled 1

Proposed Use High Embankment


Container No. 14 15 16 17 18 19





Wt. of dry soil W5=W3-W1 14.34 15.42 15.36 15.59 5.87 4.27


% 35.28 34.24 32.81 32.13 19.25 20.37







Container No. 33 34 35 1 2 3





Wt. of dry soil W5=W3-W1 14.23 15.14 15.46 15.04 6.34 6.32

Moisture Content w = 100*W4/W5 % 34.92 34.08 33.24 32.31 18.29 18.67






Container No. 9 10 11 12 13 14





Wt. of dry soil W5=W3-W1 15.27 15.53 15.24 15.67 5.99 4.37


% 34.25 33.29 32.54 31.46 18.53 18.99







Container No. 21 22 23 24 25 26





Wt. of dry soil W5=W3-W1 15.71 15.83 15.66 15.9 6.32 6.22


% 34.30 33.29 32.18 31.44 18.67 19.97






Container No. 27 28 29 30 31 32





Wt. of dry soil W5=W3-W1 15.29 15.18 15.27 15.39 5.66 4.97


% 34.72 33.72 32.94 31.90 18.37 18.71




Type of Material Soil Sample 1Proposed Use High Embankment

Mould No : 3 wt. of Mould, W1

(g) :2320 Volume of mould, V (cc) : 2250


Wt. of water 180 300 420 540 660 780


Wt. of wet soil, W3=(W2-W1) 4117 4386 4667 4863 4728 4468

Wet density, Yb = W3/V 1.830 1.949 2.074 2.161 2.101 1.986

Container No. 21 22 23 24 25 26

Wt. of container,W5 7.0 7.2 7.6 6.4 6.4 7.4



Wt. of water, W8=(W6-W7) (g) 2.71 3.11 3.98 4.59 5.81 6.09




Result from graph MDD: 1.977 gm/cc OMC: 9.59%




Wt. of water 120 240 360 480 600 720Wt. of wet soil + mould, W2 10487 10732 11000 11223 10986 10889Wt. of wet soil, W3=(W2-W1) 4107 4352 4620 4843 4606 4509Wet density, Yb = W3/V 1.825 1.934 2.053 2.152 2.047 2.004Container No. 17 18 19 20 21 22Wt. of container,W5 6.90 6.60 8.80 8.40 7.00 7.20Wt. of wet soil + cont., W6 56.87 57.37 61.69 62.49 66.49 67.32Wt. of dry soil + cont.,W7 54.67 54.27 58.00 57.53 60.35 59.84Wt. of water, W8=(W6-W7) (g) 2.20 3.10 3.69 4.96 6.14 7.48Wt. of dry soil, W9=(W7-W5) (g) 47.77 47.67 49.2. 49.13 53.35 52.64Water content w =W8/W9 % 4.61 6.51 7.51 10.10 11.50 14.20







Wt. of water 120 240 360 480 600 720


Wt. of wet soil, W3=(W2-W1) 4156 4437 4729 4869 4706 4476

Wet density, Yb = W3/V 1.847 1.972 2.102 2.164 2.092 1.989

Container No. 11 12 13 14 15 16

Wt. of container,W5 6.80 6.60 6.80 9.40 6.40 6.80



Wt. of water, W8=(W6-W7) (g) 2.22 2.57 3.79 4.60 5.61 6.21








Wt. of water 180 300 420 540 660 780


Wt. of wet soil, W3=(W2-W1) 4125 4475 4763 4898 4649 4466

Wet density, Yb = W3/V 1.833 1.989 2.117 2.117 2.066 1.985

Container No. 3 7 14 20 23 25

Wt. of container,W5 6.6 8.8 9.4 8.4 7.8 6.4



Wt. of water, W8=(W6-W7) (g) 1.08 1.89 2.58 2.77 2.99 2.90



Dry density Yd = 100x (Yb/100+w) (g/cc) 1.756 1.869 1.960 1.975 1.841 1.741Result from graph MDD: 1.988 gm/cc OMC: 9.51%


Type of Material Soil Date Tested Proposed Use High Embankment Tested By

Mould No : 3 wt. of Mould, W1 Volume of mould, V (cc) : 2250

(g) :2320


Wt. of water 210 330 450 570 690 810


Wt. of wet soil, W3=(W2-W1) 4061 4430 4713 4801 4580 4376

Wet density, Yb = W3/V 1.805 1.969 2.095 2.134 2.036 1.945

Container No. 20 24 27 30 33 34

Wt. of container,W5 8.4 6.4 7.2 6.6 9.8 7.8



Wt. of water, W8=(W6-W7) (g) 1.37 1.52 2.14 2.48 3.73 3.91





6.3 Sub-Grade Soil:


Sample: 1 Use : SubgradeType of material : Soil Weight : 3000gm


g.

Cumulative weight


19 mm 0 0 0 100

4.75 mm 408 408 13.6 86.4

2 mm 447 855 28.5 71.5

425 microns 564 1419 47.3 52.7

75 microns 930 2349 78.3 21.7



Sample: 2 Use : SubgradeType of material : Soil Weight :3000gm


g.

Cumulative weight


19 mm 0 0 0 100 4.75 mm 429 429 14.3 85.7







g.

Cumulative weight


19 mm 0 0 0 100 4.75 mm 381 381 12.7 87.3






g.

Cumulative weight


19 mm 0 0 0 100 4.75 mm 411 411 13.7 86.3





Type of Material Soil Sample 1

Proposed Use Subgrade


No. of Blows 18 22 26 32 - -

Container No. 1 2 3 4 5 6




Wt. of moisture W4=W2-W3 13.08 13.10 1307 13.11 8.50 8.23

Wt. of dry soil W5=W3-W1 37.31 38.28 39.12 41.04 43.77 41.66


% 35.32 34.21 33.40 31.93 19.42 19.75

Plasticity Index = 14.08 Average = 33.67 Average = 19.59




No. of Blows 18 23 29 35 - -

Container No. 7 8 9 10 11 12





Wt. of dry soil W5=W3-W1 42.95 44.81 42.51 44.42 38.12 37.77


% 36.42 35.29 33.95 32.90 18.64 19.02






No. of Blows 17 22 28 36 - -

Container No. 13 14 15 16 18 17





Wt. of dry soil W5=W3-W1 22.98 19.95 16.99 22.66 5.52 6.35


% 40.82 39.13 37.54 36.06 22.13 24.26





No. of Blows 17 20 25 28 - -

Container No. 18 21 22 24 10 14





Wt. of dry soil W5=W3-W1 17.34 17.96 15.74 18.26 15.49 15.79


% 31.26 30.01 29.81 28.03 20.20 19.79



Type of Material Soil Sample 1Proposed Use Subgrade



Wt. of water 180 300 420 540 600 720

Wt. of wet soil + mould, W2 10418 10624 11012 11198 11005 10733Wt. of wet soil, W3=(W2-W1) 4098 4304 4692 4878 4685 4413

Wet density, Yb = W3/V 1.821 1.913 2.085 2.168 2.082 1.962Container No. 1 2 3 4 5 6

Wt. of container,W5 9.00 6.40 6.60 9.00 8.00 8.60Wt. of wet soil + cont., W6 71.42 67.32 66.84 69.95 68.79 68.56

Wt. of dry soil + cont.,W7 68.63 64.20 62.18 64.30 61.89 61.14Wt. of water, W8=(W6-W7) (g) 2.79 3.12 4.66 5.65 6.90 7.72

Wt. of dry soil, W9=(W7-W5) (g) 59.63 57.80 55.58 55.30 53.89 52.54Water content w =W8/W9 % 4.68 5.40 8.39 10.21 12.80 14.69

Dry density Yd = 100x (Yb/100+w) (g/cc) 1.740 1.815 1.924 1.967 1.846 1.710MDD = 1.970 gm/cc OMC = 9.55%




Wt. of water 180 300 420 540 660 780


Wt. of wet soil, W3=(W2-W1) 4104 4423 4690 4872 4653 9417

Wet density, Yb = W3/V 1.824 1.966 2.084 2.165 2.068 1.944

Container No. 7 8 9 10 11 12

Wt. of container,W5 8.80 6.80 6.60 6.80 8.60 6.60



Wt. of water, W8=(W6-W7) (g) 2.79 3.75 4.31 5.76 6.63 7.54



Dry density Yd = 100x (Yb/100+w) (g/cc) 1.740 1.845 1.939 1.961 1.840 1.740Result from graph MDD 1.981gm/cc OMC 9.20%



Proposed Use Subgrade Tested By



Wt. of water 120 240 360 480 600 720


Wt. of wet soil, W3=(W2-W1) 4073 4431 4725 4867 4620 4487

Wet density, Yb = W3/V 1.810 1.969 2.100 2.163 2.053 1.994

Container No. 15 16 17 18 19 20

Wt. of container,W5 6.40 6.80 6.40 6.60 8.80 8.40



Wt. of water, W8=(W6-W7) (g) 2.23 3.28 4.77 5.74 6.34 7.41



Dry density Yd = 100x (Yb/100+w) (g/cc) 1.744 1.861 1.935 1.962 1.840 1.755Result from graph MDD 1.972gm/cc OMC 9.45%




Wt. of water 180 300 420 540 660 780


Wt. of wet soil, W3=(W2-W1) 4129 4396 4592 4862 4660 4438

Wet density, Yb = W3/V 1.835 1.954 2.041 2.160 2.071 1.972

Container No. 21 22 23 24 25 26

Wt. of container,W5 7.00 7.20 7.80 6.40 6.40 7.40



Wt. of water, W8=(W6-W7) (g) 2.61 3.67 4.34 5.73 7.37 7.75



Dry density Yd = 100x (Yb/100+w) (g/cc) 1.761 1.840 1.895 1.957 1.830 1.721Result from graph MDD = 1.969gm/cc OMC = 9.45%

6.3.4 CBR Value:

Sample 1 CBR Test for soil subgrade Proving Ring Correction factor: 7.136 MDD=1.961 gm/cc

Penetration mm

10 Blows 30 Blows 65 BlowsMould No.4 Mould No.5 Mould No.6

Load Load LoadReading Kg/cm2 Reading Kg/cm2 Reading Kg/cm2

0.5 3 21.42 6 42.82 12 85.63

1.0 4 28.54 9 64.22 16 114.18

1.5 6 42.95 12 71.86 20 142.72

2.0 7 49.95 15 107.04 22 156.99

2.5 8 57.09 17 121.31 27 192.673.0 9 64.22 19 135.58 29 206.99

4.0 11 78.50 23 164.13 34 247.67

5.0 14 99.90 27 192.67 39 278.307.5 18 128.45 35 249.76 48 348.53

10.0 21 149.86 41 292.58 53 378.31

12.5 24 131.36 45 331.17 55 397.41

CBR CALCULATIONS

Mould No. BlowsCorrected Unit Load CBR (%)

Dry Density2.5 mm 5.0 mm 2.5 mm 5.0 mm

4 10 59.00 95.00 4.31 4.62 1.765

5 30 122 192 8.91 9.34 1.860

6 65 192 278.5 14.01 13.55 1.980

Required Compaction at 97%, Hence, MDD @ 97% = .

6.3.4 CBR Value (Continued):

Sample 2 CBR Test for soil subgrade Proving Ring Correction factor: 7.136 MDD=1.976 gm/cc

Penetration mm

10 Blows 30 Blows 65 BlowsMould No.1 Mould No.2 Mould No.3

Load Load LoadReading Kg/cm2 Reading Kg/cm2 Reading Kg/cm2

0.5 3 21.41 6 42.82 11 78.50

1.0 4 28.54 9 64.22 14 99.90

1.5 6 42.82 13 92.77 18 128.45

2.0 7 49.95 16 114.18 21 149.86

2.5 8 57.09 19 135.58 25 178.403.0 10 71.36 21 149.86 27 192.67

4.0 11 78.50 24 171.26 30 214.08

5.0 13 92.77 27 192.68 33 235.497.5 15 107.04 32 228.35 35 249.36

10.0 17 121.31 35 249.76 37 264.03

12.5 19 135.58 37 264.03 39 298.30

CBR CALCULATIONS

Mould No. BlowsCorrected Unit Load CBR (%)

Dry Density2.5 mm 5.0 mm 2.5 mm 5.0 mm

1 10 57.10 92.30 4.17 4.49 1.760

2 30 136 192 9.93 9.34 1.871

3 65 180 235.5 13.14 11.46 1.994

Required Compaction at 97%, Hence, MDD @ 97% =

6.4 Mix Design for Granular Sub Base (GSB)

6.4.1 Abstract

6.4.1.1 Abstract for Blend 1:

Serial Number Type of test Result Specification limits Remarks

1 Proportion 17:51:32 - 40mm:10mm:Dust

2 Liquid Limit (%) 20.80 < 25 %

3 Plastic Limit (%) Non Plastic < 6 %

4 MDD (g/cc) 2.286 -

5 OMC (%) 5.90 -

6 CBR (%) 50.50 > 30 %

7 10% fines value KN 130.75 > 50 KN

8 Water Absorption(40 mm) (%) 1.23 < 2.0 %


10 Water Absorption(Dust) (%) 1.77 < 2.0 %




2 Liquid Limit (%) 20.80 < 25 %


4 MDD (g/cc) 2.301 -

5 OMC (%) 5.60 -

6 CBR (%) 48.30 > 30 %








2 Liquid Limit (%) 20.80 < 25 %


4 MDD (g/cc) 2.306 -

5 OMC (%) 5.90 -

6 CBR (%) 47.00 > 30 %





6.4.2 Specific Gravity and Water Absorption:

6.4.2.1 For 40mm:

S.No: Description Sample-1 Sample-2 Sample-3 Mean

1 Weight of SSD aggregate in air (W1) 6600 6657 6678

2 Weight of SSD aggregate in water (W2) 3950 4300 4228

3 Weight of oven dried aggregate in air (W3) 6525 6575 6592

4 Bulk Specific Gravity = 2.46 2.79 2.69

5 Apparent Specific Gravity = 2.53 2.89 2.79

6 Water Absorption = 1.15 1.25 1.30 1.23

6.4.2.2 For 10mm:


1 Weight of SSD aggregate in air (W1) 6757 6755 6652

2 Weight of SSD aggregate in water (W2) 4369 4355 4228

3 Weight of oven dried aggregate in air (W3) 6675 6668 6582

4 Bulk Specific Gravity = 2.80 2.78 2.72

5 Apparent Specific Gravity = 2.89 2.88 2.80

6 Water Absorption = 1.23 1.30 1.06 1.20

6.4.2.3 For Dust:


1 Weight of Pycnometer (W1) 500 500 500

2 Weight of Pycnometer + Material (W2) 1120 1120 1125

3 Weight of Pycnometer + Material + Water (W3)

1680 1680 1685

4 Weight of Pycnometer + Water (W4) 1280 1280 1280

5 Weight of SSD sample (W5) 630 633 632

6 Weight of oven dried sample (W6) 628 624 622

7 Specific Gravity

8 Water Absorption =

6.4.3 Individual Gradation

6.4.3.1 For Dust:

Trail 1:

IS Sieve Size(mm)

Weight Retained in

gms

Cumulative weight

Retained (mm)

Cumulative % retained % Passing

75 0 0 0 100

53 0 0 0 100

26.5 0 0 0 100

9.5 0 0 0 100

4.5 0 0 0 100

2.36 40 40 1.74 98.26

0.475 900 940 40.87 59.13

0.075 1020 1960 85.22 24.78

Trail 2:

IS Sieve Size(mm)

Weight Retained in

gms

Cumulative weight

Retained (mm)


75 0 0 0 100

53 0 0 0 100

26.5 0 0 0 100

9.5 0 0 0 100

4.75 0 0 0 100

2.36 33 33 1.17 98.83

0.475 1120 1153 40.74 59.26

0.075 1024 2393 84.56 15.44

Trail 3:

IS Sieve Size(mm)

Weight Retained in

gms

Cumulative weight

Retained (mm)

Cumulative % retained

% Passing

75 0 0 0 100

53 0 0 0 100

26.5 0 0 0 100

9.5 0 0 0 100

4.75 0 0 0 100

2.36 45 45 2.19 97.81

0.475 1041 1086 51.73 48.27

0.075 710 1096 85.52 14.48

6.4.3.2 For 40mm Coarse Aggregate:

Trail 1:

Weight of Dry Material: 20000 gms

IS Sieve Size(mm)

Weight Retained in

gms

Cumulative weight

Retained (mm)


75 0 0 0 100

53 460 460 2.30 97.70

26.5 19540 20000 100 0

9.5 0 20000 100 0

4.5 0 20000 100 0

2.36 0 20000 100 0

0.475 0 20000 100 0

0.075 0 20000 100 0

Trail 2:


IS Sieve Size(mm)

Weight Retained in

gms

Cumulative weight

Retained (mm)


75 0 0 0 100

53 850 850 4.25 95.75

26.5 19150 20000 100 0

9.5 0 20000 100 0

4.75 0 20000 100 0

2.36 0 20000 100 0

0.475 0 20000 100 0

0.075 0 20000 100 0

Trail 3:


IS Sieve Size(mm)

Weight Retained in

gms

Cumulative weight

Retained (mm)


% Passing

75 0 0 0 100

53 450 450 2.25 97.75

26.5 19550 20000 100 0

9.5 0 20000 100 0

4.75 0 20000 100 0

2.36 0 20000 100 0

0.475 0 20000 100 0

0.075 0 20000 100 0

6.4.3.3 For 10mm Coarse Aggregate:

Trail 1:


IS Sieve Size(mm)

Weight Retained in

gms

Cumulative weight

Retained (mm)


75 0 0 0 0

53 0 0 0 0

26.5 0 0 0 0

9.5 6160 6160 62 38.00

4.5 3510 9670 97 3.000

2.36 280 9950 99.50 0.50

0.475 50 10000 100 0

0.075 0 10000 100 0

Trail 2:


IS Sieve Size(mm)

Weight Retained in

gms

Cumulative weight

Retained (mm)


75 0 0 0 100

53 0 0 0 100

26.5 0 0 0 100

9.5 3890 3890 71 29.27

4.75 1510 5400 98 2.00

2.36 89 5489 99.80 0.20

0.475 11 5500 100 0

0.075 0 5500 100 0

Trail 3:


IS Sieve Size(mm)

Weight Retained in

gms

Cumulative weight

Retained (mm)


% Passing

75 0 0 0 100

53 0 0 0 100

26.5 0 0 0 100

9.5 4070 4070 74 26

4.75 1390 5460 99.29 0.71

2.36 40 5500 100 0

0.475 0 5500 100 0

0.075 0 5500 100 0

6.4.3.4 Summary of Individual Aggregate Gradation for Granular Sub Base:

40 mm% of passing 10mm % of passing Dust % of passing

IS Sieve Size (mm) Trail 1 Trail 2 Trail 3 Avg Trail 1 Trail 2 Trail 3 Avg Trail 1 Trail 2 Trail3 Avg

75 100 100 100 100 100 100 100 100 100 100 100 100

53 98 96 98 97 100 100 100 100 100 100 100 100

26.5 0 0 0 0 100 100 100 100 100 100 100 100

9.5 0 0 0 0 38 29.27 26.00 31 100 100 100 100

4.75 0 0 0 0 3 1.82 0.73 2 100 100 100 100

2.36 0 0 0 0 1 0.20 0 0 98.26 98.83 97.81 98.30

0.475 0 0 0 0 0 0 0 0 59.13 59.26 48.29 55.56

0.075 0 0 0 0 0 0 0 0 14.78 15.44 14.48 14.90

72

IS Sieve Size

Individual Gradation Blending percentageDesign

Gradation

Morth Limits

40 mm 10 mm Dust40

mm 10 mm Dust Lowerlimit

Upperlimit17% 51% 32%

75 100 100 100 17 51 32 100 100 100

53 97.07 100 100 16.50 51 32 99.50 80 100

26.5 0 100 100 0 51 32 83.00 55 90

9.5 0 31.22 100 0 16 32 47.92 35 65

4.75 0 1.95 100 0 0.99 32 32.99 25 55

2.36 0 0 98.30 0 0 31.46 31.58 20 40

0.425 0 0 55.56 0 0 17.76 17.78 10 25

0.075 0 0 14.90 0 0 4.77 4.77 3 10

6.4.4 Blending Proportions: 6.4.4.1 Blend 1:

Sieve Analysis:

Sample 1:

Weight of Sample = 30000 gms

IS Sieve SizeWeight

Retained (gm)

Cumulative Weight

Retained (gm)

Cumulative % Retained % Passing Lower limit Upper limit

75 0 0 0 100 100 100

53 420 420 1.40 98.60 80 100

26.5 4260 4680 15.60 84.40 55 90

9.5 9910 14590 48.63 51.37 35 65

4.75 4890 19480 64.93 35.05 25 55

2.36 610 20090 66.97 33.0 20 40

0.425 4790 24880 82.93 17.07 10 25

0.075 3000 27880 92.93 7.07 3 10

73

Sample 2:


IS Sieve Size

Weight Retained

(gm)

Cumulative Weight

Retained (gm)


75 0 0 0 100 100 100

53 564 564 1.88 98.12 80 100

26.5 5280 5844 19.48 80.52 55 90

9.5 8146 19992 46.64 53.36 35 65

4.75 6262 20274 67.58 32.42 25 55

2.36 690 20964 69.88 30.12 20 40

0.425 3831 24795 82.65 17.35 10 25

0.075 3630 28425 94.75 5.25 3 10

Sample 3:


IS Sieve SizeWeight

Retained (gm)

Cumulative Weight

Retained (gm)


75 0 0 0 100 100 100

53 410 410 1.52 98.48 80 100

26.5 4030 4440 16.4 83.56 55 90

9.5 9605 14045 52.0 48.0 35 65

4.75 3850 17895 66.3 33.70 25 55

2.36 585 18480 68.04 31.56 20 40

0.425 4355 22835 84.6 15.43 10 25

0.075 1950 24785 91.8 8.20 3 10

IS Sieve Size

Individual Gradation Blending percentage Design Gradation

Morth Limits

40 mm 10 mm Dust 40 10 Dust Lower Upper74

mm mmlimit Limit17% 40% 34%

75 100 100 100 17 40 34 100 100 100

53 91.17 100 100 15.50 40 34 99.50 80 100

26.5 0 100 100 0 40 34 83.00 55 90

9.5 0 91.32 100 0 15.30 34 49.30 35 65

4.75 0 1.96 100 0 4.95 34 34.95 25 55

2.36 0 0 96.30 0 0 33.42 33.54 20 40

0.425 0 0 53.56 0 0 18.05 18.89 10 25

0.075 0 0 14.37 0 0 5.07 5.07 3 10

6.4.4.2 Blend 2:

Sieve Analysis:

Sample 1:


IS Sieve Size

Weight Retained

(gm)

Cumulative Weight

Retained (gm)


75 0 0 0 100 100 100

53 750 750 2.50 97.50 80 100

26.5 4230 4980 16.60 83.40 55 90

9.5 9372 14352 47.84 52.16 35 65

4.75 5199 19551 65.17 34.83 25 55

2.36 795 20346 67.82 32.18 20 40

0.425 4191 24537 81.79 18.21 10 25

0.075 3588 28125 93.75 6.25 3 10

Sample 2:


75

IS Sieve Size

Weight Retained

(gm)

Cumulative Weight

Retained (gm)


75 0 0 0 100 100 100

53 750 750 2.50 97.50 80 100

26.5 4230 4980 16.60 83.40 55 90

9.5 9372 14352 47.84 52.16 35 65

4.75 5199 19551 65.17 34.83 25 55

2.36 795 20346 67.82 32.18 20 40

0.425 4191 24537 81.79 18.21 10 25

0.075 3588 28125 93.75 6.25 3 10

Sample 3:


IS Sieve Size

Weight Retained

(gm)

Cumulative Weight

Retained (gm)


75 0 0 0 100 100 100

53 750 750 2.50 97.50 80 100

26.5 4230 4980 16.60 83.40 55 90

9.5 9372 14352 47.84 52.16 35 65

4.75 5199 19551 65.17 34.83 25 55

2.36 795 20346 67.82 32.18 20 40

0.425 4191 24537 81.79 18.21 10 25

0.075 3588 28125 93.75 6.25 3 10

6.4.4.3 Blend 3:

76

IS Sieve Size

Individual Gradation Blending percentageDesign

Gradation

Morth Limits

40 mm 10 mm Dust40

mm 10 mm Dust Lower limit

Upper limit15% 51% 34%

75 100 100 100 15.00 51.00 34.00 100 100 100

53 97.07 100 100 14.56 51.00 34.00 99.56 80 100

26.5 0 100 100 0 51.00 34.00 85.00 55 90

9.5 0 31.22 100 0 15.92 34.00 49.92 35 65

4.75 0 1.95 100 0 0.99 34.00 34.99 25 55

2.36 0 0 98.30 0 0.12 33.42 33.54 20 40

0.425 0 0 55.56 0 0.00 18.89 18.89 10 25

0.075y 0 0 14.90 0 0.00 5.07 5.07 3 10

Sieve Analysis:

Sample 1:


IS Sieve Size

Weight Retained

(gm)

Cumulative Weight

Retained (gm)


75 0 0 0 100 100 100

53 1284 1284 4.28 95.72 80 100

26.5 4266 5550 18.50 81.50 55 90

9.5 8505 14055 46.85 53.15 35 65

4.75 5067 19122 63.76 36.24 25 55

2.36 2094 21216 70.72 29.28 20 40

0.425 2739 23955 79.85 20.15 10 25

0.075 4320 28275 94.25 5.75 3 10

Sample 2:


77

IS Sieve Size

Weight Retained

(gm)

Cumulative Weight

Retained (gm)


75 0 0 0 100 100 100

53 1095 1095 3.65 96.35 80 100

26.5 3540 4635 15.45 84.55 55 90

9.5 8970 13605 45.35 54.65 35 65

4.75 6417 20022 66.74 33.26 25 55

2.36 633 20655 68.85 31.15 20 40

0.425 3582 24237 80.79 19.21 10 25

0.075 3627 27864 92.88 7.12 3 10

Sample 3:


IS Sieve Size

Weight Retained

(gm)

Cumulative Weight

Retained (gm)


75 0 0 0 100 100 100

53 1425 1425 4.75 95.25 80 100

26.5 3927 5352 17.84 82.16 55 90

9.5 9543 14895 49.65 50.35 35 65

4.75 4431 19326 64.42 35.58 25 55

2.36 606 19932 66.44 33.56 20 40

0.425 3912 23844 79.48 20.52 10 25

0.075 4461 28305 94.35 5.65 3 10

6.5 Mix-Design for Wet Mix Macadam

6.5.1 Gradation

78

6.5.1.1 Sample 1:

Proportion of Mix (%) 40 mm=33% 20 mm=16% 10 mm=18% Dust=33%

I.S. Sieve (mm) Weight Retained (gm)

Cumulative Wt. Retained % Retained % Passing

Specified Limits as per

MoRTH Table.400-11

53 0 0 0 100 100

45 0 0 0 100 95-100

22.4 5690 5690 29.90 70.10 60-80

11.2 3339 9029 47.45 52.55 40-60

4.75 3440 12469 65.52 34.48 25-40

2.36 1003 13472 70.79 29.21 15-30

0.600 1848 15320 80.50 19.50 08-22

0.075 3199 18519 97.31 2.69 0 - 8

Pan 511

6.5.1.2 Sample 2:





MoRTH Table.400-11

53 0 0 0 100 100

45 0 0 0 100 95-100

22.4 5666 5666 29.85 70.15 60-80

11.2 3729 9395 49.50 50.50 40-60

4.75 3232 12627 66.53 33.47 25-40

2.36 1323 13950 73.50 26.50 15-30

0.600 2525 16475 86.80 13.20 08-22

0.075 1651 18126 95.50 95.50 0 - 8

Pan 854

6.5.1.3 Sample 3:

79





MoRTH Table.400-11

53 0 0 0 100 100

45 0 0 0 100 95-100

22.4 5968 5968 29.33 70.67 60-80

11.2 4309 10276 50.50 49.50 40-60

4.75 3236 13512 66.40 33.60 25-40

2.36 1455 14967 73.55 26.45 15-30

0.600 2412 17379 85.40 14.60 08-22

0.075 2360 19740 97.00 3.00 0 - 8

Pan 610 12

80

6.5.2 Flakiness Index & Elongation Index:

Sieve Size (mm)

Total Wt. of agg. ret. on sieves

[A] (gm)

Wt. of agg. passing from

thickness gauge [B] (gm)

Wt. of agg. retained on thickness gauge [C]

(gm)

Wt. of agg. ret. on length gauge after

ret. on thickness

gauge [D] (gm)

Passing Retained

50.0 40.0 40.0 31.5 3368 410 2958 50031.5 25.0 2592 380 2212 -25.0 20.0 2290 260 2030 70020.0 16.0 1925 140 1785 35016.0 12.5 1641 125 1516 32012.5 10.0 1038 98 940 19010.0 6.3 1079 64 1015 47Total 13933 1477 12456 2107

RESULTS : Flakiness Index = B/A X 100 (%) 10.60 Elongation Index = D/C X 100 (%) 16.92 Combined FI and EI (%) 27.52

Sieve Size (mm)Total Wt. of agg.

ret. on sieves [A] (gm)




(gm)


ret. on thickness

gauge [D] (gm)

Passing Retained

63.0 50.0 50.0 40.0 40.0 25.0 2989 388 2601 20025.0 20.0 2103 189 1914 25820.0 16.0 1304 137 1167 24116.0 12.5 998 144 854 18812.5 10.0 502 88 414 12210.0 6.3 302 68 234 80Total 8198 1014 7184 1089


6.5.2 Flakiness Index & Elongation Index (Continued):

Sieve Size (mm)


[A] (gm)




(gm)


ret. on thickness

gauge [D] (gm)

Passing Retained

63.0 50.0 50.0 40.0 40.0 25.0 2217 252 1965 10525.0 20.0 1850 110 1740 24720.0 16.0 632 105 527 10216.0 12.5 465 98 367 8212.5 10.0 642 122 520 8710.0 6.3 956 133 823 147Total 6762 820 5942 770


Sieve Size (mm)


[A] (gm)




(gm)


ret. on thickness

gauge [D] (gm)

Passing Retained

50.0 40.0 40.0 31.5 3300 380 2920 45031.5 25.0 2590 380 2210 -25.0 20.0 2300 260 2040 65020.0 16.0 1907 125 1782 35016.0 12.5 1622 125 1497 32012.5 10.0 1020 88 932 19010.0 6.3 1024 64 960 47Total 13763 1422 12341 2007


6.5.3 Aggregate Impact Value:

Sample 1:

Description Trial No. 1 Trial No. 2 Trial No. 3

Weight of surface dry sample passing 12.5 mm and retained on 10 mm IS sieves, W1 (gms)

343.90 350.08 347.85

Weight of fraction passing 2.36 mm IS sieve, after the test, W2 (gms) 47.21 44.60 43.90

Weight of fraction retained on 2.36 mm IS sieve after the test, W3 (gms) 296.69 305.48 303.95

A.I.V. = (W2 / W1)X100 13.73 12.74 12.62

Average value of A.I.V. (%) 13.03

Sample 2:


Weight of surface dry sample passing 12.5 mm and retained on 10 mm IS sieves, W1 (gms)

342.60 352.00 346.90



A.I.V. = (W2 / W1)X100 12.10 13.50 13.10


Sample 3:


Weight of Aggregate, W1 (gms) 342.60 352.00 346.90



A.I.V. = (W2 / W1)X100 12.96 13.50 13.10


6.5.4 Wet Mix Macadam Abstract

Mix Proportions : 40mm-33% 20mm- 16% 10mm -18% DUST -33%

S.No Properties Standards Trial Average Result

Acceptance Criteria As per

MoRTH1 2

1 Gradation _ Within the specified envelope As per MoRTH table 400-11

2 MDD (gm/cc) IS:2720 (Part-VIII) 2.327 2.327 2.327 _

3 OMC (%) IS:2720 (Part-VIII) 5.4 5.4 5.4 _

4 Liquid Limit IS:2720 (Part-V) 22.2 22 22.1 Less Than 25%

5 Plastic Index IS:2720 (Part-V) _ _ NON-Plastic Less Than 6%

6Flakiness &

Elongation Indices (%)

IS:2386 (Part-I) 26.59 27.52 27.1 Max .30%

7 AIV (%) IS:2386 (Part-IV) 12.9 13.03 13.0 Max .30%

8 Water Absorption (%) IS:2386 (Part-III)

40mm=0.95

Max .2%20 mm =1.0

10mm=1.18

85

6.5.5 Wet Mix Mecadam Design Summary

I.S. Sieve (mm) 40mm 20mm 10mm Dust 53.00 100.00 100.00 100.00 100.00 45.00 100.00 100.00 100.00 100.00 22.40 6.50 94.93 100.00 100.00 11.20 0.11 0.51 84.07 100.00 4.75 0.00 0.15 0.73 98.35 2.36 0.00 0.00 0.37 85.85 0.600 0.00 0.00 0.08 47.08 0.075 0.00 0.00 0.20 14.34

Blending

Proportion 32.0% 16% 19% 33.0% 100% I.S. Sieve

(mm) 40 mm 20 mm 10mm Dust Blending results Median Specification

limits53.00 32.00 16.00 19.00 33.00 100.00 100.0 10045.00 32.00 16.00 19.00 33.00 100.00 97.5 95-10022.40 2.08 15.19 19.00 33.00 69.27 70.0 60-8011.20 0.04 0.08 15.97 33.00 49.09 50.0 40-604.75 0.00 0.00 0.14 32.46 32.59 35.0 25-452.36 0.00 0.00 0.07 28.33 28.40 22.5 15-300.600 0.00 0.00 0.02 15.54 15.55 15.0 8-220.075 0.00 0.00 0.04 4.73 4.77 4.0 0-8

86

6.5.6 Laying of Wet Mix Macadam:

Wet mix macadam base shall consist of laying and compacting clean, crushed graded

aggregate and granular material, premixed with water to a dense mass on prepared sub base in

accordance with the specifications.

Coarse aggregate proposed to be used in WMM are obtained by crushing the rocks,

obtained from approved quarries. Before removing the rock, the quarry area is stripped of

earth loam, clay and vegetable matter.

Independent tests will be carried out on this material as follows:

Sieve analysis.

Los Angeles abrasion.

Aggregate impact value.

Combined flakiness & elongation indices.

Blending (Mix Design).

Modified proctor density.

Liquid limit & plasticity index of portion through 425 micron sieve.

Mixing: Proposed base material will be obtained by mixing various sizes of aggregates

(as per approved mix design) & water in the wet mix macadam plant. The Wet mix macadam

plant consists of 4 chambers, which can carry 40mm, 20mm, 10mm and dust. The mixing is

done according to the design proportions. Each chamber releases required amount of material

so that the exact mix design is obtained. WMM material will be carried to the site in dumpers

of adequate capacity.

87

Laying and compaction: WMM material will be laid in layers on prepared sub – base

using mechanical pavers or motor grader to maintain required thickness and slope and to

achieve finished surface in narrow areas, WMM will be spread manually, in layers.

Figure 6.1: At the WMM mixing plant.

Each layer will be compacted with 10 T Vibro Roller, to achieve required degree of

compaction i.e. 98% of modified density. The areas not accessible to roller will be compacted

with plate compactor or mini rollers. Top surface will be checked for its designed levels,

before & after compaction & material will be removed or added as required. Segregated

material will not be allowed to be placed. The tolerance on levels shall not exceed 12 mm and

deviation from 3000mm straight edge shall not exceed 10mm. After final compaction, surface

will be checked for its finish and top levels. Any segregated material like only coarse or only

fine will be removed and the pocket will be filled with premixed material. While checking the

top surface levels it may be necessary to remove excess material or to add material.

88

Chapter-7

Substitute for Bitumen layer- Foamed Bitumen

7.1 Introduction

The topics described so far in this project report are related to the different pavement

layers like Embankment, Soil Subgrade, Granular Sub-base and Wet Mix Macadam. The next

layer for this flexible pavement is Dense Bitumen Macadam (DBM). As on date (of

submission of this report), the construction of DBM layer has not yet started for this approach

road. We had made a lot of research for an alternate, cost-effective and more durable material

to replace the regular Bitumen layer. This material is nothing but, the Foamed Bitumen. This

part of the report is purely an innovative idea and is nowhere used in the present road

construction by Gammon. The Foamed Bitumen Technology is not completely introduced in

India. The proceeding part will explain the concept behind this idea.

As per the present trend, an engineer will look forward for the process that may allow

him to save bitumen, lay strong and durable roads at a lesser cost, re-use the aggregate

scrapped off the worn out road, open the road built by him to traffic immediately on its laying

and continue laying of a road even if a sudden downpour begins! This certainly seems to be a

figment of imagination, a far-fetched idea but has become possible with the advent of a new

technique: foamed bitumen.

Many countries around the world, including Australia, Brazil, Canada, Finland,

Mexico, Norway, South Africa, UK and the USA, are trying the technique in an enthusiastic

manner and the results are encouraging. Foamed bitumen has been successfully used in new

road construction, in strengthening of existing roads, as a base course material and to correct

the subsidence caused in roads due to heavy traffic. Its area of application may further widen

as it is showing full stability even under extreme climatic conditions with successful use in

countries like Saudi Arabia, Iran, Nigeria and South Africa. Next is the turn of India and

whole of Asia.

7.2 Foamed bitumen stabilization:

Foamed bitumen stabilisation is a road construction technique whereby hot bitumen is

used to bind the existing or imported granular material to produce a flexible pavement

material for use in base and sub-base pavement layers, and in particular for road

rehabilitation.

Foam bitumen is a mixture of hot bitumen, water and air. It is produced when cold

water is added to the hot bitumen thus raising a lot of foam. As the bitumen is hot, water

coming in contact with it evaporates causing foaming of bitumen along with. The quantity of

water added is only 2 to 3% of weight of bitumen. The bitumen expands up to 15 to 20 times

its original volume, its extent depending upon the quantity of water added and the temperature

of hot bitumen. In this foamed state, the bitumen has a very large surface area and an

extremely low viscosity. This enables a much less quantity of foamed bitumen to coat the aggregate. The

water is added by the method of injection by use of a specially designed spray-bar and under

controlled conditions. The foamed bitumen is then mixed with the cold and moist aggregate to

produce the ready-mix for laying on roads.

7.3 Recycled Aggregate:

The aggregate used for mixing with foamed bitumen may be the worn out material

milled off the already laid road. In the conventional road building process, this aggregate is

removed and disposed off and new aggregate is used. But while using foamed bitumen, this

aggregate can be put to reuse as there is no reduction in strength or durability of roads on this

account. Thus a lot of saving on account of cost of aggregate can be made. It is however to be

checked that the milled aggregate is well graded. Its sieve analysis may be done to check the

fine material content in it. In foamed bitumen technology, availability of fine material in

aggregate carries importance. Therefore, if required, crushed stone may be needed to be added

to the aggregate at its optimum moisture content. This fine material in fact gets mixed with

foamed bitumen to form a mortar which coats and binds the coarse aggregates.

7.4 Technology involved:

The recycled aggregate acts as the base material for the relaying of roads and the

foamed bitumen acts as the binding material for this aggregate. For the successful production

of foamed bitumen, the most important step is to control the physical conditions of

temperature and pressure. With regard to this, the two important characteristics of foamed

bitumen to be controlled to produce quality material are its expansion and half-life.

Expansion of foamed bitumen is the ratio of new volume to the original volume of

bitumen. As already stated, it ranges from 15 to 20. It means the new volume has to be 15 to

20 times the original volume. Half-life is the time in which foamed bitumen loses 50% of its

expansion. Generally half-life is of about 10-12 seconds; in other words, half of bitumen’s

expansion is lost in 20 to 25 seconds. Clearly, the best foamed bitumen will be the one with

more expansion and more half-life. The temperature of bitumen, the amount of water added to

the bitumen and the pressure under which the bitumen is injected into the expansion chamber,

all control these two characteristics of foamed bitumen.

Figure 7.1: Compaction of Foamed Bitumen layer.

A highly interesting aspect of foamed bitumen road construction is that the mix of

aggregate and foamed bitumen need not be heated in a hot mix plant but can be laid in a cold

condition itself. Not only this, if the produced mix is not laid by the closure of a working day,

it can continue to lie on the roadside and be laid in position the next day. The mixed material

can even be stockpiled on the roadside and will remain soft till the time it is laid and

compacted. After compaction, the road can immediately be opened to traffic. Thus, the road-

closing hours with ‘road work in progress’ sign boards which trouble road-users are reduced

to the minimum when foamed bitumen is used. Traffic disruptions are therefore, much less.

And what comes as a big relief to a road- builder is that the laying of foamed bitumen mix can

be continued even if it starts raining. Moreover, the cold process helps in lesser consumption

of fuel, thus bringing in savings.

After the laying the road with foamed bitumen, it is sealed with a thin layer of asphalt.

The result is a high-grade stabilised pavement.

7.5 Spraying technology:

To ensure that the foamed bitumen gets homogeneously distributed in the material to

be recycled, the machines carry high quality spray bars with 16 nozzles for spraying foamed

bitumen over full working width. The spray bars can be controlled by the operator with

respect to the road width under consideration for spraying. The foamed bitumen’s properties

of Expansion and Half-life can be checked and corrected by taking foam samples from an

external test nozzle provided in the machines and then comparing their parameters with

desired results.

Figure 7.2: Laying of Foamed Bitumen.

7.6 Foamed Bitumen Classification:

The table below shows the classification of Foamed Bitumen based on the Unconfined

Compressive Strength (UTS) and Indirect Tensile Strength (ITS):

Material

ClassificationUCS, after 3 days of

accelerated air-dried (kPa)ITS, after 3 days of

accelerated air-dried (kPa)

FB1 1400-2000 300-500

FB2 1400-2000 100-300

FB3 700-1400 300-500

FB4 700-1400 100-300

Table 7.1: Classification of Foamed Bitumen.

7.7 Advantages of Foamed Bitumen:

The following advantages of foamed bitumen roads over those with cement or

bitumen emulsion as binding agents can be listed:

Earlier laid aggregate gets reused without compromise on strength or quality. This is a

big advantage. Wastage as well as disposal problems are avoided.

Standard penetration grade bitumen is used. So there is no problem on account of non-

availability of bitumen or any special quality or grade of bitumen is required.

Very small quantities of foamed bitumen as binder are required. Thus the process is

highly cost effective.

Foamed bitumen can be produced directly in the recycler. Additional machinery is

thus avoided.

The foamed bitumen treated material can even be stored.

The work can proceed even on rain-wet roads.

Lower moisture contents are required in comparison to bitumen emulsion stabilisation

and hence wet spots are minimised.

After construction, the pavement can tolerate heavy rainfall with only minor surface

damage under traffic, and hence is less susceptible to the effects of weather than other

methods of stabilisation.

It can be carried out insitu and hence is quicker than other methods of rehabilitation.

The foamed binder increases the shear strength and reduces the moisture susceptibility

of granular materials. The strength characteristics of foamed asphalt approach those of

cemented materials, but foamed asphalt is flexible and fatigue resistant.

Foam treatment can be used with a wider range of aggregate types than other cold mix

processes.

Reduced binder and transportation costs, as foamed asphalt requires less binder and

water than other types of cold mixing.

Saving in time, because foamed asphalt can be compacted immediately and can carry

traffic almost immediately after compaction is completed.

Energy conservation, because only the bitumen needs to be heated while the

aggregates are mixed in while cold and damp (no need for drying).

Environmental side-effects resulting from the evaporation of volatiles from the mix

are avoided since curing does not result in the release of volatiles.

7.8 Projects accomplished:

Some of the projects accomplished around the world using Cold recyclers and foamed

bitumen are tabulated below:

Sr. Country Job Machinery Used Remarks

1. Saudi

Arabia

Heavy traffic

desert road of

380 km length

1. Wirtgen Cold

Recyclers WR 2500

2. Mobile slurry

mixing Plants WM 400

3. Vibratory Rollers

4. Pneumatic Tire

rollers.

Total length of 380 km

was finished in 180

days only. 5% foamed

bitumen and 2% cement

slurry were used as

binders to do 35000 sq.

m area daily.

2. USA Rehabilitation of

canal road

network

1. Wirtgen Cold

Recyclers WR 2500


3. Pneumatic Tire

rollers

1.5% Cement and 3%

foamed bitumen were

used as binders.

3. Iran Rehabilitation of

Motorway

1. Wirtgen Cold Recyclers

WR 25002.

2. Cement Slurry Mixing Plant WM 10003.


4. Pneumatic Tire rollers

3.5% foamed bitumen

and 1.0% cement slurry

were used.2.Total area

of 8 lac sq. m was laid.

Table 7.2: Projects accomplished by using Foamed Bitumen.

7.9 Case Studies:

Using the Wirtgen Cold Recycler WR 2500 with mobile slurry mixing plant WM 400,

a heavy traffic desert road of 380 km length was finished in Saudi Arabia in just six

months. Five per cent foamed bitumen and two per cent cement slurry were used as

binders to cover a 35,000-sq. m area every day. Vibratory rollers and pneumatic tire

rollers were used for compaction.

In the US, the same Wirtgen cold recycler, the WR 2500, was used for rehabilitation

of canal road network. The compaction machinery was the same as the one which

accompanied the recycler in Saudi Arabia. Here, 1.5 per cent cement and three per

cent foamed bitumen acted as binders.

Rehabilitation of a motorway was done in Iran using 3.5 per cent foamed bitumen and

1 per cent cement slurry as binders and using Wirtgen Cold Recycler WR 2500,

cement slurry mixing plant WM 1000 for mixing of slurry and vibratory rollers and

pneumatic tire rollers as compactors. Here, a total area of 8 lakh sq. m was laid

through this process.

In the US again, the road leading to the Hollywood emblem on the slopes of Mount

Lee had become brittle due to repeated use in carrying supply and security vehicles. A

cold recycling machine was considered the most suitable equipment for its repair at a

minimum cost. A Wirtgen cold recycler type WR 2500 was used to recycle its upper

layer to a depth of 150 mm. The milled material of gravel and asphalt was

homogeneously mixed with 3 per cent of foamed bitumen as the binding agent.

Equipped with a powerful 610 HP engine, the WR 2500 had no problem pushing the

bitumen tanker truck uphill through the serpentine bends. Compaction of the recycled

pavement posed a great difficulty on the steep hillside, though. Therefore, a single

drum compactor closely followed the cold recycling machine. A single-drum

compactor 3412 and a double vibratory roller HD 120 worked immediately behind the

WR 2500. A pneumatic tyred roller was also deployed to complete the operation by

sealing the new surface. A road length of 2.3km with working width between 5 to 8

metres was successfully completed.

Australia had run their first foamed bitumen trail for a road of 1.6km of length in

Gladfield, Queensland during the year 1997.

Foamed bitumen was used in the Rainbow Beach Road construction in Gympie,

Queensland. Mix designs of 3, 4, 5% foamed bitumen with 2% lime is used for this

purpose.

The Cunningham Highway, situated to the east of Inglewood, Queensland was

constructed by using 4% foamed bitumen with 1.5% quicklime.

Other successfully completed projects include the Jingshen Expressway project in

China, a motorway in Italy, the second longest highway of USA in California, the

Zion Canyon Drive near Arizona, and many more. These projects have been

economical and revealed wonderful re-use of laid material.

Chapter-8

Conclusions

Flexible pavements can be constructed and maintained quickly hence reduces

congestion.

These pavements are generally dark in colour which offer significant reduction in road

surface glare and assist in making line markings stand out in contrast to the road.

These pavements are durable, safe and long lasting compared to rigid pavements.

These pavements are fully recyclable.

Flexible pavements provide smooth, safe surfaces and minimize fuel consumption.

They can be easily opened and patched.

Foamed bitumen cold mixes are gaining in popularity owing to their good

performance, ease of construction and compatibility with a wide range of aggregate

types. As with all bituminous mixes, it is essential to have a proper mix design

procedure for foamed asphalt mixes in order to optimize the usage of available

materials and to optimize mix properties. Fortunately, for foamed asphalt mixes, the

mix design can be accomplished by relatively simple test procedures and by adhering

to certain restrictions with respect to the materials used.

Rehabilitation using foamed bitumen has proved to be successful because of its ease

and speed of construction, its compatibility with a wide range of aggregate types and

its relative immunity to the effects of weather. There are now well developed

procedures for the design of foamed bitumen stabilisation which should be followed.

Foamed bitumen has the potential to be used throughout.

Foamed asphalt base stabilization produces a stronger, longer-lasting pavement at a

fraction of the cost and time than would be required for conventional reconstruction.

Foamed asphalt is a viable, cost-effective, and environmentally sensitive method to

rehabilitate a roadway or street which has significantly deteriorated from wear, or

which was not originally constructed with a proper structural section.

References

S.K. Khanna & C.E.G. Justo (2001) ‘Highway Engineering’ 8th edition, New Chand

& Bros publication.

S.K. Khanna & C.E.G. Justo (2002) ‘Highway Material Testing’ 4th edition, New

Chand & Bros publication.

Martin Rogers (2003) ‘Highway Engineering’ Blackwell publishing Ltd.

Foamed Asphalt base stabilization, By Don Raffaelli, Technology Transfer Program

Institute of Transportation Studies, University of California Berkeley.

Ministry of Surface transport (MOST), section 400 (Sub-base preparation).

Ministry of Surface transport (MOST), section 900 (Quality control).

Ministry of Surface transport (MOST), section 2400 (Surface & sub surface

exploration).

Ministry of Surface transport (MOST), section 3000 (Maintenance of roads).

http://www.greenmixinc.com/pics/foamasph.pdf

http://asphalt.csir.co.za/FArefs/CAPSA%20'99%20Engelbrecht%20128.pdf

http://www.auststab.com.au/pdf/tp26.pdf

https://www.onlinepublications.austroads.com.au/items/AP-T178-11


http://www.fao.org/docrep/T0579E/t0579e06.htm#4.1 introduction

http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT-KANPUR/transport_e/

TransportationII/objective/6-objective.htm

http://training.ce.washington.edu/wsdot/modules/07_construction/07-2_body.htm

http://www.docstoc.com/docs/21795521/Benefits-of-Flexible-Pavements-Brochure-

(Read-Only)

http://www.preservearticles.com/2012020922970/what-are-the-advantages-and-

disadvantages-of-pavements.html

http://www.hiwaystabilizers.co.nz/media/16458/fbr_in_nz.pdf

http://www.alakona.com/pdf/Alakona%20Report.pdf

http://www.alakona.com/pdf/Alakona%20Report.pdf

http://www.hiwaystabilizers.co.nz/media/16458/fbr_in_nz.pdf

http://www.preservearticles.com/2012020922970/what-are-the-advantages-and-disadvantages-of-pavements.html

http://www.preservearticles.com/2012020922970/what-are-the-advantages-and-disadvantages-of-pavements.html

http://www.docstoc.com/docs/21795521/Benefits-of-Flexible-Pavements-Brochure-(Read-Only)

http://www.docstoc.com/docs/21795521/Benefits-of-Flexible-Pavements-Brochure-(Read-Only)

http://training.ce.washington.edu/wsdot/modules/07_construction/07-2_body.htm

http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT-KANPUR/transport_e/TransportationII/objective/6-objective.htm

http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT-KANPUR/transport_e/TransportationII/objective/6-objective.htm

http://www.fao.org/docrep/T0579E/t0579e06.htm#4.1%20introduction



http://www.auststab.com.au/pdf/tp26.pdf

http://asphalt.csir.co.za/FArefs/CAPSA%20'99%20Engelbrecht%20128.pdf

http://www.greenmixinc.com/pics/foamasph.pdf

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