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DOKUZ EYLÜL UNIVERSITY
GRADUATE SCHOOL OF NATURAL AND APPLIED SCIENCES
THE EFFECT OF BASALT AGGREGATE ON THE PERFORMANCE OF WEARING COURSE (A CASE
STUDY OF UŞAK - KULA HIGHWAY)
by
Bülent KAÇMAZ
January, 2006
İZMİR
THE EFFECT OF BASALT AGGREGATE ON THE PERFORMANCE OF WEARING COURSE (A CASE
STUDY OF UŞAK - KULA HIGHWAY)
A Thesis Submitted to the
Graduate School of Natural and Applied Sciences of Dokuz Eylül University
In Partial Fulfillment of the Requirements for the Degree of Master of Science in
Civil Engineering, Transportation Program
by
Bülent KAÇMAZ
January, 2006
İZMİR
M.Sc THESIS EXAMINATION RESULT FORM
We have read the thesis entitled “THE EFFECT OF BASALT AGGREGATE
ON THE PERFORMANCE OF WEARİNG COURSE (A CASE STUDY OF
UŞAK-KULA HIGHWAY)” completed by BÜLENT KAÇMAZ under
supervision of ASSISTANT PROFESSOR DR. SERHAN TANYEL and we
certify that in our opinion it is fully adequate, in scope and in quality, as a thesis for
the degree of Master of Science.
Assist.Prof.Dr. Serhan TANYEL
Supervisor
(Jury Member) (Jury Member)
Prof.Dr. Cahit HELVACI Director
Graduate School of Natural and Applied Sciences
ii
ACKNOWLEDGEMENTS
The author wants to declare his gratitude and thanks to Assist.Prof.Dr. Serhan
Tanyel, supervisor of the thesis, and the Professor Mehmet Uluçaylı, previous
supervisor of the thesis who was the honorary leader of Transportation Section for
their kind and invaluable support. He also expresses his special thanks to Ali Topal
for his guidance and helpful criticisms and Assist.Prof.Dr. Burak Şengöz for his
support from the beginning of the study.
Furthermore the author sincere thanks to Fatma Orhan, Chief of Bituminous
Mixture Laboratory at General Directorate of Highways and to Hasan Ali Kandemir,
Chief of Bituminous Mixture Laboratory at II. Division of Highways for their help
and orientation in laboratory tests.
The author would like to express his deepest thanks to his family, Mehmet-
Fikriye- Serkan Kaçmaz for their love, patience and wholehearted supports in whole
of his life.
Bülent KAÇMAZ
iii
THE EFFECT OF BASALT AGGREGATE ON THE PERFORMANCE OF
WEARING COURSE (A CASE STUDY OF UŞAK-KULA HIGHWAY)
ABSTRACT
Increase in traffic volume, tyre pressure, axle load cause serious deformations on
highways and demand for new solutions to prevent these deformations. The causes of
deformations can be classified in three main groups that are effect of traffic, effects
of weathering and lack of adequate supporting capacity of base and sub-base course.
Aggregates are one of the two main constituent of hot mix asphalt and composes
90-95% of it by weight. In this study the effect of basalt aggregate on the
performance of wearing course is investigated.
After the detailed examination of physical and chemical properties of mineral
aggregates and types of bituminous binders, world-wide hot mix asphalt design
methods has been explained.
One of the major reasons of pavement deformation is the wrong action during
field applications. In chapter four; field applications are explained starting from plant
operations, transportation, surface preparation, mix placement till compaction to
understand causes of failures and their effect to the performance of pavement.
In the fifth chapter, types and causes of pavement deformation in hot mix asphalt
and the rutting relation with aggregate are examined.
Detailed experimental procedures are explained in chapter six. Four different
Marshall mix design is prepared with basalt aggregate, mineral filler and limestone
aggregate and the performance of mixes are investigated with rutting tests.
Keywords: Basalt aggregate, performance of pavements and causes of failures,
rutting, Marshal mix design method.
iv
BASALT KULLANIMININ AŞINMA TABAKASI PERFORMANSI
ÜZERİNDEKİ ETKİLERİ (UŞAK-KULA YOLU ÖRNEĞİ)
ÖZ
Gün geçtikçe artan trafik hacmi, dingil yükü ve lastik basınçları yol
kaplamalarındaki bozulmaları ve bu bozulmaları geciktirmek için çözüm arayışlarını
arttırmaktadır. Yol kaplamalarındaki bozulmaların nedenleri çevresel etkiler, temel
veya alttemelden kaynaklanan taşıma gücü yetersizliği, trafik etkisi olarak üç ana
grupta toplanabilir.
Agregalar bitumlü sıcak karışımların iki önemli bileşeninden biri olup ağırlıkça
ağırlıkça 90% - 97% sini oluştururlar. Bu çalışmada basalt agregasının aşınma tabakası
performansı üzerindeki etkileri incelenmiştir.
Bitümlü Sıcak Karışımlarda kullanılan mineral agregalar ve bitümlü bağlayıcıların
tipleri, fiziksel ve kimyasal özellikleri detaylı olarak incelendikten sonra tüm dünyada
kullanılan Bitümlü Sıcak Karışım dizayn metodları anlatılmıştır.
Yol kaplamalarında oluşan bozulmaların önemli bir nedeni de uygulama
esnasındaki hatalardır. Bozulma nedenlerinin daha iyi kavranabilmesi için dördüncü
bölümde arazi uygulamaları karışımın plentte hazırlanmasından başlayarak, taşınması,
yol yüzeyinin hazırlanması, karışımın serilmesi ve sıkıştırlması başlıkları altında
açıklanmış bu aşamalarda yolun performansını etkileyecek faktörlere değinilmiştir.
Bitümlü sıcak karışımlarda meydana gelen bozulmalar ve nedenleri beşinci
bölümde incelenmiş, tekerlek izi oluşumunun agrega ile ilişkileri saptanmaya
çalışılmıştır.
Altıncı bölümde, labaratuvar çalışmalarında yapılan deney prosedürleri ayrıntılı
olarak anlatılmıştır. Bazalt agregası, mineral filler ve kalker agregası ile dört farklı
Marshall karışım dizaynı yapılmış ve tekerlek izi deneyleri yapılarak karışımların
performansları incelenmiştir.
Anahtar sözcükler: Bazalt agregası, yol kaplamalarının performansı ve bozulma
nedenleri, tekerlek izi, Marshall karışım dizayn yöntemi.
v
CONTENTS
Page
THESIS EXAMINATION RESULT FORM................................................................. ii
ACKNOWLEDGEMENTS........................................................................................... iii
ABSTRACT................................................................................................................... iv
ÖZ.................................................................................................................................. v
CONTENTS.................................................................................................................. vi
CHAPTER ONE - INTRODUCTION ...........................................................................1
CHAPTER TWO - BITUMINOUS MATERIALS IN ROAD CONSTRUCTION...3
2.1 Asphalt .....................................................................................................................3
2.2 Basic Refining Process.............................................................................................3
2.3 Constitution and Structure of Bitumen ....................................................................5
2.3.1 Bitumen Constitutions.......................................................................................6
2.3.2 Bitumen Structure .............................................................................................8
2.4 Asphalt Types Used in Paving .................................................................................8
2.4.1 Asphalt Cement.................................................................................................8
2.4.2 Cutback Asphalts ..............................................................................................9
2.4.3 Emulsified Asphalts ..........................................................................................9
2.4.4 Foamed (Expanded) Asphalt...........................................................................10
2.5 Aggregates for Bituminous Mixtures.....................................................................10
2.5.1 Sources of Aggregates ....................................................................................11
2.5.2 Classification of Aggregate.............................................................................12
CHAPTER THREE - MIX DESIGN PROCEDURES.............................................. 18
3.1 Marshall Method ....................................................................................................18
3.2 Hveem Method.......................................................................................................20
vi
3.3 SHRP Method (Superpave)....................................................................................22
3.4 Hubbard – Field Method ........................................................................................25
CHAPTER FOUR - HOT MIX ASPHALT.................................................................26
4.1 Plant operations......................................................................................................26
4.1.1 Batch Plant Operations and Components........................................................26
4.1.2 Drum Mix Plant Operations and Components................................................28
4.2 Transportation ........................................................................................................30
4.3 Surface Preparation ................................................................................................32
4.4 Mix Placement .......................................................................................................35
4.4.1 Tractor Unit.....................................................................................................36
4.4.2 Screed Unit......................................................................................................38
4.4.3 Forces Acting On the Screed ..........................................................................40
4.4.4 Factors Affecting Mat Thickness and Smoothness.........................................41
4.5 Compaction ............................................................................................................41
4.5.1 Stages of compaction ......................................................................................42
4.5.2 Factors Affecting Compaction ........................................................................44
4.5.3 Compaction Equipment...................................................................................47
CHAPTER FIVE-TYPES OF PAVEMENT FAILURES AND THEIR CAUSES..52
5.1 Pavement Performance...........................................................................................52
5.2 Types of Failures....................................................................................................53
5.3 Causes of Failures ..................................................................................................53
5.4 Bituminous Mixture Behavior................................................................................55
5.5 Permanent Deformations........................................................................................55
CHAPTER SIX - LABORATORY TESTS..................................................................58
6.1 Aggregate and Bitumen Tests Used In Design ......................................................58
6.1.1 The Los Angeles Abrasion Test......................................................................58
6.1.2 The Crushing Test ...........................................................................................58
vii
6.1.3 The Stripping Test...........................................................................................60
6.1.4 The Sieve Analysis Test .................................................................................61
6.1.5 Bulk Specific Gravity and Water Absorption Of Coarse Aggregate ..............63
6.1.6 Specific Gravity and Water Absorption of Fine Aggregate. ..........................65
6.1.7 Bulk Specific Gravity of Bitumen ..................................................................71
6.1.8 Penetration Of Bituminous Materials .............................................................73
6.2 Marshall Mix Design Method ................................................................................74
6.2.1 Preparing Specimens.......................................................................................74
6.2.2 Bulk Specific Gravity of Marshall Samples ...................................................76
6.2.3 Marshall Stability and Flow Test ....................................................................76
6.2.4 Theoretical Maximum Specific Gravity of the ...............................................77
6.4.1 Results Of Four Different Marshall Mix Design ............................................78
6.3 General Description of Pavement Rutting Test .....................................................95
6.3.1 Principles of the L.P.C. Pavement Rutting Test .............................................95
6.3.2 Test Procedure.................................................................................................97
6.5 Results of the Pavement Rutting Tests ................................................................103
CHAPTER SEVEN - CONCLUSIONS AND SUGGESTIONS..............................105
REFERENCES.............................................................................................................108
viii
CHAPTER ONE
1 INTRODUCTION
Human beings have always been in need of transportation. War and conquest
played an important role in the development of early roads so the transportation has
vital importance for human beings to socialize and survive. By the invention of the
wheel, the construction of planned and specially built ways on which the wheeled
vehicles could operate efficiently become necessary. The earliest human road builders
predate recorded history by thousands of years. Romans of about 312 B.C. are known
as the first road builders who used basic lime cements to hold their large stones
together. The roads of the late 1700s and early 1800s did not use a binder material
and usually relied on aggregate interlock to provide cohesion. Bituminous binding
materials and surface layers began to appear in pavement construction in the early
1800s. Around the beginning of the 19th century, binding agents began to be used to
help aggregate cohesion and improve the durability of roads. However, today there
are so many types of construction methods in highway pavements, but basically
pavements are classified in two major types; flexible and rigid pavements.
As the years passed, the demand for better roads is increased and today the
increasing traffic volumes, tyre pressures and axle roads bring the pavement failures
as the main problem in road construction.
In this study, what will be concerned is the effect of basalt aggregate to the
performance of the wearing course which is the hardware of the transport network.
Certain areas of the road like climbing lanes, crossings, and bus stops where the laid
pavement highly stressed because of the slow motion of heavy vehicles, therefore,
rutting has become a major cause of loss of serviceability of asphalt pavements. The
distresses which occur on these critical areas can be prevented during the design
period, by establishing a strong skeleton .
1
2
Hot mix asphalt (HMA) may be defined as a combination of aggregate and asphalt
binder mixed together at high temperatures that form a hard, strong construction
material when cooled to surrounding temperatures. The weight and volume of
mineral aggregates used in asphaltic mixtures are respectively at the rate of 90-95%
of mixture weight, 75-85% of mixture volume. Physical and mineralogical properties
of mineral aggregates on which the load bearing capacity of a pavement depends
affects directly the properties of a mixture, the workability of a fresh mixture and the
performance of a pavement. The more asphaltic mixtures are workable, the more they
are compactable. Researches show that easily compactable asphaltic mixtures can rut
easily and quickly under traffic. In contrast, mixtures with low workability prove to
be less prone to rutting under the same conditions.
In this study four different asphalt mix design is prepared to determine the
optimum combination of aggregate and asphalt binder to achieve the properties of
stability, durability, flexibility, fatigue resistance, skid resistance and rut resistance in
the mixture by forming a strong skeleton. Physical and chemical properties of mineral
aggregates and types of bituminous binders are examined, field applications are
explained, types and causes of pavement deformation in hot mix asphalt are
examined, four different Marshall mix design is prepared with basalt aggregate,
mineral filler and limestone aggregate and the performance of mixes are investigated
with rutting tests.
CHAPTER TWO
2 BITIMINIOUS MATERIALS IN ROAD CONSTRUCTION
2.1 Asphalt
Asphalt is one of the two major constituents of HMA and as a simple definition it
plays the role of being the principal binding agent in HMA. Various of asphalt
definitions exists .For engineering purposes ASTM D 8 provides more clear
definitions as follows:
Table 2.1 Asphalt Definitions
asphalt A dark brown to black cementitious material in which the predominating constituents are bitumen, which occur in nature or are obtained in petroleum processing.
asphalt cement
A fluxed or unfluxed asphalt specially prepared as to quality and consistency for direct use in the manufacture of bituminous pavements, and having a penetration at 25° C (77° F) of between 5 and 300, under a load of 100 grams applied for 5 seconds.
bitumen A class of black or dark-colored (solid, semi-solid or viscous) cementitious substances, natural or manufactured, composed principally of high molecular weight hydrocarbons, of which asphalts, tars, pitches, and asphaltenes are typical.
flux A bituminous material, generally liquid, used for softening other bituminous materials.
2.2 Basic Refining Process
Asphalt cement is refined from the crude oil which is a complex mixture of
hydrocarbons differing in molecular weight and boiling range.
Crude oil is heated in a large furnace to about 340ºC and partially vaporized. It is
then fed into a distillation tower where the lighter components vaporize and are
drawn off for further processing. The residue from this process (the asphalt) is usually
3
4
fed into a vacuum distillation unit where heavier gas oils are drawn off. Asphalt
cement grade is controlled by the amount of heavy gas oil remaining. Other
techniques can then extract additional oils from the asphalt. Depending upon the
exact process and the crude oil source, different asphalt cements of different
properties can be produced. Additional desirable properties can be obtained by
blending crude oils before distillation or asphalt cements after distillation. This
process is illustrated in Figure 2.1.
Figure 2.1 Petroleum asphalt flow Chart
5
2.3 Constitution and Structure of Bitumen
Asphalt chemistry can be described on the molecular level as well as on the
intermolecular (microstructure) level. On the molecular level, asphalt is a mixture of
complex organic molecules that range in molecular weight from several hundred to
several thousand.
Although these molecules exhibit certain behavioral characteristics, the behavior
of asphalt is generally ruled by behavioral characteristics at the intermolecular level –
the asphalt’s microstructure.
The asphalt chemical microstructure model described here is based on SHRP
findings on the microstructure of asphalt using nuclear magnetic resonance (NMR)
and chromatography techniques. The SHRP findings describe asphalt microstructure
as a dispersed polar fluid (DPF). The DPF model explains asphalt microstructure as a
continuous three-dimensional association of polar molecules (generally referred to as
"asphaltenes") dispersed in a fluid of non-polar or relatively low-polarity molecules
(generally referred to as "maltenes") All these molecules are capable of forming
dipolar intermolecular bonds of varying strength. Since these intermolecular bonds
are weaker than the bonds that hold the basic organic hydrocarbon constituents of
asphalt together, they will break first and control the behavioral characteristics of
asphalt. Therefore, asphalt’s physical characteristics are a direct result of the
forming, breaking and reforming of these intermolecular bonds or other properties
associated with molecular superstructures.
The result of the above chemistry is a material that behaves (1) elastically through
the effects of the polar molecule networks, and (2) viscously because the various
parts of the polar molecule network can move relative to one another due to their
dispersion in the fluid non-polar molecules.
6
2.3.1 Bitumen Constitutions
Bitumen is a complex chemical mixture of polar and non-polar organic molecules,
and small quantities of metals. Chemical composition of bitumen is absolutely
complex but this composition may be defined in two main groups which are
alphaltenes and maltenes. Maltenes can be subdivided into saturates aromatics and
resins. The proportion and microstructure of these molecules determines asphalt’s
physical behavior.
Elementary analysis of bitumens manufactured from a variety of crude oils shows
that most bitumen contain;
Carbon 82 – 88 %
Hydrogen 8-11 %
Sulphur 0 – 6 %
Oxygen 0 – 15 %
Nirogen 0 – 1 % (Read, 2003, p.36)
The methods available for separating bitumen into fractions can be classified as:
Solvent extraction
Adsorption by finely divided solids and removal of unadsorbed solution by
filtration
Chromatography
Molecular distillation used in conjunction with one of the above techniques.
7
Solvent extraction is attractive as it is a relatively rapid technique but the
separation obtained is generally poorer than that which results from using
chromatography where a solvent effect is combined with selective adsorption.
Similarly, simple adsorption methods are not as effective as column chromatography
in which the eluting solution is constantly re-exposed to fresh adsorbent and different
equilibrium conditions as it progresses down the column. (An eluting solution is one
that is used to remove an adsorbed substance by washing). Molecular distillation is
lengthy and has limitations in terms of the extend to which type separation and
distillation of high molecular weight components of bitumen can be effected.
Chromatographic techniques (Middleton,1958,p.47) have, therefore, been most
widely used to define bitumen constitution. The basis of he method is to initially
precipitate asphaltenes using n-heptane followed by chromatographic separation of
the remaining material.
2.3.1.1 Asphaltenes
Aphaltenes are black or brown insoluble solids which are composed of carbon,
hydrogen, some nitrogen sulphur and oxygen. They are highly polar and most
complex constituent of asphalt. The average molecular weight of asphaltenes range
from 1000 to 100 000 and they have a particle size of 5 to 30 nm.
2.3.1.2 Resins
Resins are dark brown soluble semi solid or solids which are composed of carbon,
hydrogen and small amount of nitrogen sulphur and oxygen. They are polar, highly
adhesive and dispersing agents for asphaltenes. The average molecular weight of
resins range from 500 to 50 000 and they have a particle size of 1 to 5 nm.
8
2.3.1.3 Aromatics
Aromatics are dark brown viscous liquids which are composed of carbon chains .
They are non-polar and soluble in high molecular weight hydrocarbons. The average
molecular weight of them range from 300 to 2000 and they form 40 – 65 % of
bitumen.
2.3.1.4 Saturates
Saturates are straw or white viscous oils which consists straight and branch chain
aliphatic hydrocarbons together with alkyl-naphthenes and some alkyl-aromatics.
They are non-polar viscous oils. The average molecular weight of them range from
300 to 2000 and they form 5 – 20 % of bitumen.
2.3.2 Bitumen Structure
Bitumen is defined as a colloidal system which is composed of asphaltenes
dissolved in maltenes. The amount and characteristics of asphaltenes, resins,
aromatics and saturates in an asphalt cement determines physical properties and
performance of the hot mix asphalt mixture.
2.4 Asphalt Types Used in Paving
2.4.1 Asphalt Cement
It is an asphalt that has been specially refined as to quality and consistency for
direct use in the manufacture of asphalt pavements, and has penetration at 25ºC of
between 5 and 300. Asphalt cement has to be heated to an appropriate high
temperature in order to be fluid enough to be mixed and placed.
9
2.4.2 Cutback Asphalts
Cutback asphalt is a blend of asphalt cement and petroleum solvent to reduce the
asphalt viscosity for lower application temperatures. After cutback asphalt is applied,
the solvent evaporates and remaining asphalt cement will perform its function as a
binder. They are classified into three main types according to their relative
evaporation rates. A rapid curing (RC) cutback asphalts evaporate at a fast speed and
composed of asphalts cement and a solvent of naphtha or gasoline. A medium curing
(MC) cutback asphalts evaporates at the medium speed and composed of asphalts
cement and a solvent of intermediate volatility similar to kerosene. A slow curing
(SC) cutback asphalt containing an oil of relatively low volatility. They are primarily
used for prime coat, tack coat, surface treatments, road-mix operations and stockpile
patching mixtures, however because of environmental regulations and loss of high
energy during production cutback asphalt usage is decreasing.
2.4.3 Emulsified Asphalts
Emulsified asphalt is composed of asphalt cement, water and emulsifying agent.
Because the asphalt cement will not dissolves in water it is in the form of globules in
water as a suspension. The water is called continuous phase and the globules of
asphalt are called the discontinuous phase. Depending upon the type of emulsifier,
emulsified asphalts are classified as anionic, cationic and non-ionic. If the
emulsifying agent is anionic, emulsion is anionic hence asphalt particles are
negatively charged and this type is used with aggregates that have positive surface
charges like limestone. Similarly, if the emulsifying agent is cationic, emulsion is
cationic hence asphalt particles are positively charged and this type is used with
aggregates that have negative surface charges like siliceous aggregates (such as
sandstone, quartz and siliceous gravel).
Generally, emulsions have the color of dark brown before applied. When the
asphalt cement starts to adhere to the surrounding material (aggregate, existing
surface, subgrade, etc.) the color changes from brown to black and the emulsion is
10
said to have "broken" or “set”. In anionic emulsified asphalt; when the opposite
charges of asphalt droplets and surface of the aggregate (or existing layer) reacts,
water will evaporate and emulsified asphalt will “set” or “break”. In Cationic
emulsified asphalts this setting process is electro-chemical.
Emulsified asphalts are further classified according to their setting rate which is
controlled by type and amount of emulsifying agent. These types are (rapid-setting)
(RS), medium setting (MS) and slow setting (SS). The time required to break and set
also depends upon the application rate, the temperature of the surface onto which it is
applied and environmental conditions.
2.4.4 Foamed (Expanded) Asphalt
Foamed asphalt is formed by combining hot asphalt binder with small amounts of
cold water. When the cold water comes in contact with the hot asphalt binder it turns
to steam, which becomes trapped in tiny asphalt binder bubbles. The result is a thin-
film, high volume asphalt foam with approximately 10 times more coating potential
than the asphalt binder in its normal liquid state (Little & Fox, 2000). This high
volume foam state only lasts for a few minutes, after which the asphalt binder
resumes its original properties. Foamed asphalt can be used as a binder in soil or
base course stabilization, and is often used as the stabilizing agent in full-depth
asphalt reclamation.
2.5 Aggregates for Bituminous Mixtures
National Asphalt Pavement Association defines aggregate as “a collective term for
the mineral materials such as sand, gravel and crushed stone that can be used alone or
with a binding medium (such as water, asphalt, portland cement, lime, etc.) to form
compound materials (such as asphalt concrete, portland cement concrete, etc.)” and
ASTM Designation D 8 defines aggregate as “a granular material of mineral
composition such as sand, gravel, shell, slag, or crushed stone, used with a cementing
11
medium to form mortars or concrete or alone as in base courses, railroad ballasts,
etc.”
Aggregates usually comprises between 90 and 95 percent of the weight and at least
80-85 % of the volume of bituminous mixtures. The type and properties of aggregates
have a direct influence on load carrying capacity and pavement performance. In
pavement construction, a detailed discussion of the physical properties of aggregates
is important for the understanding of the design and performance of bituminous
mixtures.
2.5.1 Sources of Aggregates
Aggregates used in road construction may be natural, processed or synthetic
origin. Most widely used aggregates are obtained from local supplies of natural rock.
Aggregates are imposed to crushing which reduces the size of the rock particles to
make them suitable for use in bituminous mixtures. Processed aggregates are
obtained by crushing and screening from natural rocks. Therefore, processed
aggregates are also naturally occurring materials.
Synthetic aggregates may be obtained as a by-product of some industrial processes
or from the processing of raw materials for ultimate use as aggregates. “In Turkey
and in the United States, the primary source of industrially prepared aggregates for
road building is blast furnace slag which is a by product of the smelting (Uluçaylı,
2001 p.84)
Other synthetic aggregates are manufactured by high temperature processing of
clay, shale, slate and other natural materials. Synthetic aggregates are typically light
and may have high resistance to abrasion. Materials obtained from the recycling of
waste products such as glass and tires have also been studied as potential sources of
aggregates for bituminous mixtures, especially because of the increasing awareness of
the need for protection of the environment (CHEN, 1995, p.1248).
12
2.5.2 Classification of Aggregate
2.5.2.1 Petrologic Classification
Natural rocks are classified by geologists into three groups depending on their
origin—igneous, sedimentary, and metamorphic.
Igneous Rocks
Igneous rocks are formed by the cooling of molten rock magma as it moves toward
or on the surface of the earth. Igneous rocks are classified based on size of the crystal
grains and on composition as either acidic or basic.
The classification of igneous rocks is based on their mineral content. The main
mineral component of magma is silica. Total silica quantity of the magma varies
between 35-75 % by weight. Silicates are the largest group of rock-forming minerals.
The silicates comprise in increasing order of the complexity of atomic structure and
in decreasing order of mineral specific gravity olivine, pyroxene, amphiboles
(hornblende), biotite and muscovite micas, feldspars and quartz. Rocks having high
silica content are termed acid, and having low silica content that is a large group of
basic oxides, are termed basic. Acid rocks contain 66% total silica basic rocks have
45-52 %. Between these rocks, intermediate rocks have 52-66 % total silica and ultra
basic rocks contain less than 45%.
Acid rocks contain free quartz 10 % or more generally, while basic ultra basic
rocks do not have any. Intermediate rocks have a low free quartz percentage.
(Collis&Fox, 1985)
Sedimentary Rocks
Sedimentary rocks are primarily formed either by the deposition of insoluble
residue from the disintegration of existing rocks or from deposition of the inorganic
remains of marine animals. Classification is based on the predominant mineral
13
present as calcareous (limestones, chalks, etc.). siliceous (chert, sandstone, etc.), or
argillaceous (shale, etc.).
Sedimentary rocks are divided in to two main groups according to their formation
modes: clastic rocks and sedimentary rocks formed in-situ.
Clastic rocks include the consolidated fragmentary materials that have been eroded
from pre-existing rocks. These rocks are classified in decreasing order of grain size as
conglomerate, breccia, sandstone (grit stone), and shale (mudstone). Sandstones and
grit stones are used as aggregates in road construction.
Limestone and flint are sedimentary rocks formed in-situ and they are used for
road construction. The origins of limestones are chemical organic or the combination
of them. They are composed of calcium carbonate in the form of calcite, organic
remains, fossils, and may also contain magnesium carbonate as magnesian limestone.
Dolomitic limestone contains both the dolomite and calcite. Limestones may contain
impurities such as clay, mud, and quartz grains. Flints are irregularly shaped nodules,
which occur in horizontal layers and vertical joints in the chalk. Flint particles are
hard and brittle. The properties of flint are not ideal for the coarse aggregate of,
durable, bituminous mixtures for roads and airfields, although their abrasion
resistance is high. (Collis&Fox, 1985)
The most important characteristic of sedimentary or layered rocks is their flat and
layered structure, bedding and stratification properties. The physical properties of
sedimentary rocks depend upon the mineral composition, texture, fabric, structure,
cementation, and porosity.
Most minerals in clastic sediments are the same as primary igneous rocks,
sedimentary rocks and metamorphic rocks. Clastic sedimentary textures consist of the
following components: sorting, roundness, packing, and fabric. (Collis&Fox, 1985)
14
Metamorphic Rocks
Metamorphic rocks are igneous or sedimentary rocks chat have been subjected to
heat and/or pressure sufficient to change their mineral structure so as to be different
from the original rock. Metamorphic rocks are generally crystalline in nature with
grain sizes from fine to coarse.
These rocks are classified into two main groups. Contact metamorphic rocks,
which alteration has been caused by the action intense heat at cooling process and
regional metamorphic rocks, which alteration has been caused by the combined
action of pressure and heat in the deeps of earth’s crust. Minerals of metamorphic
rocks are more stable than the parent rock material.
Table 2.2 Desirable Properties of Rocks for HMA (Cordon, 1979)
Hardness, Resistance to Surface Crushed Rock type Toughness Slrippingt Texture Shape Igneous Granite Fair Fair Fair Fair Syenite Good Fair Fair Fair Diorite Good Fair Fair Good Basalt (trap rock) Good Good Good Good Diabase (trap rock) Good Good Good Good Gabbro (trap rock) Good Good Good Good Sedimentary Limestone, dolomite Poor Good Good Fair Sandstone Fair Good Good Good Chert Good Fair Poor Good Shale Poor Poor Fair Fair Metamorphic Gneiss Fair Fair Good Good Schist Fair Fair Good Fair Slate Good Fair Fair Fair Quartzite Good Fair Good Good Marble Poor Good Fair Fair Serpentine Good Fair Fair Fair
15
2.5.2.2 Group Classification
A practical classification system of aggregates was needed to provide the
systematic selection of aggregates, and deciding on the suitability of a particular
aggregate source for a specific engineering purpose.(Pike,1990,p.280)
Table 2.3 Group Classification of Aggregates
1 Artifical Group Crushed brick slags calcined bauxite synthetic aggregates.
2 Basalt Group Andesite basalt basic porphyrite doleristof all kinds including thearalite
and teschenite epidiorite lamprop quartz-dolerite spilite.
3 Flint Group Chert, flint.
4 Gabbro Group Basic diorite basic gneiss gabbro hornblende-rock norite peridotite picrite
serpentinite.
5 Granite Group Gnesis granite granodiorite granulite pegmalite quartz-diorite syenite.
6 Gristone Group (Including fragmental volcanic rocks) arkose greywacke grint sandstone.
7 Hornfels Group Contact-altered rocks of all kinds expecr marble.
8 Limestone Group Dolomite limestone marble.
9 Porphyry Group Aplite dacite felsite granophyre keratophyre microgranite pophyry quartz-
porphyrite rhyolite trachyte
2.5.2.3 Mineralogical Classification
Natural aggregates are composed of minerals and the mineralogy of aggregates
influence the performance of bituminous mixtures. For example, the adhesion of
asphalt cement to the aggregate surface is higher in carbonate aggregates than in
siliceous aggregates. The presence of certain minerals as coating on the surface of the
aggregate particles affects the band with the asphalt cement and the propensity to
absorb moisture.
Clay, gypsum, iron oxides, silt and minerals may have either poor adhesion with
the asphalt binder or a propensity to absorb moisture and break the band between the
aggregate and the asphalt. Certain minerals such as quartz and feldspars are hard and
resistant to polish, enabling the asphalt mixture to maintain its skid resistance under
the abrasive effect of traffic. Aggregates from sedimentary rocks such as limestone
16
and dolomite, in contrast, can have a tendency to be polished under the action of
traffic. (Chen, 1993)
ASTM standard C 294-86 gives a description of some of the more common or
important minerals found in aggregates mineralogical classification is help in
recognizing properties of aggregate but cannot provide a basis for predicting its
performance in mixtures. The ASTM classification of minerals is summarized in
Table 2.4 and the desirable properties of rocks for HMA are given in Table 2.5.
Table 2.4 Rock and Mineral Constituents in Aggregates (Neville, 1993)
Minerals Igneous rocks Metamorphic rocks Silica Granite Marble Quartz Syenite Metaquartzite Opal Diorite Slate Chalcedony Gabbro Phyllite Tridymite Peridotile Schist Cristobalite Pegmatite Amphibolite Silicates Volcanic glass Homfels Feldspars Obsidian Gneiss Ferromagnesian Pumice Serpentinite Hornblende Tuff Augite Scoria Clay Perlite ltlites Pitdistone Kaolins Felsite Chloriics Basalt Mica Sedimentary rocks Carbonate Conglomerate Calcite Sandstone Dolomite Quartzite Sulfate Graywacke Gypsum Subgraywacke Anhydrite Arkose Iron sulfide Claystone. stltstone, Pyrite argillite, and shale Marcasite Carbonates Pyrrhotite Limestone Iron oxide Dolomite Magnetite Marl Hematite Chalk Goethite Chen Limonite
17
2.5.2.4 Chemical Classification
The chemical composition of aggregates is generally given in terms of an oxide
that is not informative of their potential performance in bituminous mixture.
Nonetheless, the prance of certain substances can lead the performance problems. For
instance, the presence of water-soluble moisture absorbing substances can produce
mixtures that are susceptible to moisture damage in the form of aggregate stripping
raveling, or loss of stability. Other substances may be susceptible to oxidation,
hydration or carbonation.
Figure 2.2 Schematic Diagram of Marshall Method (Chen, 1993, p.1364)
CHAPTER THREE
3 MIX DESIGN PROCEDURES
The purpose of asphalt mix design is determining the optimum combination of
aggregate and asphalt binder to achieve the properties of stability, durability,
flexibility, fatigue resistance, skid resistance, impermeability and workability in the
mixture. Several methods like; Marshall method, Hveem method, Superpave method,
Hubbard-Field method, Aamas Method have been developed to decide what
aggregate to use, what asphalt binder to use and what the optimum combination of
these two major component should be in the mixture.
3.1 Marshall Method
The basic concepts of the Marshall mix design method were developed by Bruce
Marshall from Mississippi Highway Department around 1939 and then improved by
the U.S. Army. Marshall method is the most common method used throughout the
world probably because it is simple, compact, its apparatus are light, portable and
inexpensive and it was used by the U.S. military all over the world during and after
second World War.
Primary usage of Marshall method is for mixtures containing maximum size of
aggregate of up to 25,4 mm (1 in) and there are three major procedure of this method;
determination of bulk specific gravity, measurement of Marshall stability and flow,
and analysis of specimen density and void content. The Marshall method is illustrated
in Figure 3.1.
18
Fi
gure
3.1
Sch
emat
ic D
iagr
am o
f Mar
shal
l Met
hod
(Che
n, 1
993,
p.1
364)
19
20
One advantage of the Marshall method is its attention to density and void properties
of asphalt mixtures. This analysis ensures the proper volumetric proportions of mixture
materials for achieving a durable HMA. (Superpave Level 1 p.14)
Use of the Marshall method to determine the job mix production does not mean that
the mix produced will perform satisfactorily during placement and compaction or long-
term under traffic. Mixes that have high Marshall stability values may still shove under
the rollers and/or undergo permanent deformation (rutting) when subjected to heavy
loads. Mixes have adequate VMA, however, normally perform significantly better than
mixes made with the same aggregate and asphalt cement but that are low in VMA
content. (U.S.Army Corps.,1991,p.1- 19)
3.2 Hveem Method
Hveem mix design method was developed by Francis Hveem from California
Division of Highways in the late 1920s and 1930s. The basic concept of this method is
to determine optimum asphalt content by a series of tests including; centrifuge kerosene
equivalent test to find asphalt content, preparing specimens that contain below and
above optimum asphalt content, stability test to determine resistance to deformation, and
a swell test to determine the permeability and effect of water on specimens.
The basic assumptions of this method can be summarized as follows; (a) Stability is a
function of aggregate particle friction and mix cohesion, (b) Optimum asphalt binder
content is dependent upon aggregate surface area and absorption. (c) HMA durability
increases with more asphalt binder.
The aim of the Hveem method is to select a mixture with well-graded aggregates and
with as much asphalt binder as the mixture tolerates without losing stability. Also, a
minimum of 3 % of VTM (percent of void) is required in the mixture. (Chen, 1995,
p.1366) The Hveem design method is illustrated in Figure 3.2;
Fi
gure
3.2
Sch
emat
ic d
iagr
am o
f Hve
em M
ix D
esig
n m
etho
d (C
hen,
199
3, p
.136
7)
21
22
A primary advantage of the Hveem method that Hveem stability is a direct
measurement of the internal friction component of shear strength The main differences
of Hveem method and other mix design methods are the kneading compactor which uses
rotating base for compaction and the Hveem stabilometer.
Figure 3.3 Schematic of stability – durability relationship of hot-mix Asphalt, illustration philosophy of
selecting design asphalt content.
3.3 SHRP Method (Superpave)
The Marshall and Hveem design methods don’t provide procedures to measure
fundamental mechanical properties of HMA mixtures. The results are test-specific, and
their validity resides primarily on the past experience accumulated over many years of
use and empirical correlations between mix design results and performance results. For
these reasons, a new system for material selection and design of bituminous mixtures
23
has been developed by SHRP of the Federal Highway Administration (FHWA). The
new system known as superior asphalt pavements (Superpave). Superpave consists of
two major parts, the Superpave asphalt binder analysis and the Superpave asphalt
mixture design and analysis. It is considered to be a superior system for grading asphalt
binders, selecting aggregate materials, conducting asphalt mix design , and predicting
pavement performance.(Wang, et al.,2000)
Figure 3.4 Structure of the Superpave Mix Design System
24
The volumetric analysis of the Hveem and Marshall methods provides the basis for
the Superpave mix design method. This method was designed to replace the Hveem and
Marshall methods. The Superpave system ties asphalt binder and aggregate selection
into the mix design process, and considers traffic and climate as well. The compaction
devices from the Hveem and Marshall procedures have been replaced by a gyratory
compactor and the compaction effort in mix design is tied to expected traffic. The
mixture design is carried out in accordance with three different levels of expected traffic,
expressed in terms of equivalent single axle load (ESAL) repetitions. The degree of
refinement and complexity of the design procedure depends on the expected traffic.
The Superpave mix design method consists of 7 basic steps;
1. Aggregate selection.
2. Asphalt binder selection.
3. Sample preparation (including compaction).
4. Performance Tests.
5. Density and voids calculations.
6. Optimum asphalt binder content selection.
7. Moisture susceptibility evaluation.
25
Table 3.1 Recommended Design Traffic Level 1, 2, and 3 Mix Designs
Design Level Design Traffic (80 kN ESALs)
1(low) ≤106
2(intermediate) ≤107
3(high) >107
3.4 Hubbard – Field Method
The basic concept of Hubbard – Field method was developed by Prevost Hubbard -
F.C. Field. Two aim of this method is density – void analysis and stability. Hubbard –
Field method is used just for laboratory design and mixtures that have more than 65 %
passing through No.10 sieve. Stability is tested by applying vertical force to pass
test ring. (Kenedy et al, 1994)
3.5 Aamas method
The asphalt – aggregate mixture analysis system method of mix design, recently
published by the National Cooperative Highway Research Program, should provide
mixture that are better able to perform under traffic. The resilient modulus value,
indirect tensile strength, creep modulus value are more related to the distress
mechanisms that affect the durability of an asphalt pavement: fatigue permanent
deformation, moisture damage, disintegrating, and low-temperature cracking.
(U.S.Army Corps.,1991, p 1-20)
CHAPTER FOUR
4 HOT MIX ASPHALT
4.1 Plant operations
A Hot Mix Asphalt Plant blends, heats, dries aggregates and mixes aggregates with
asphalt cement to produce HMA that contains the desired proportions of asphalt and
aggregate that meets all specified requirements. There are different types of plants,
which are batch plants, continuous mix plants, parallel-flow drum plants, counter flow
drum plants, and double barrel drum plants and these types of plant can also be
classified as stationary or portable.
Purpose of each plant is same, however flow of materials and operation of mixing are
different. Two major and most commonly used types of plants, the batch plants and the
drum mixer plants, will be taken in consideration in this part.
The difference between the two plants is that batch plants dry the aggregate and then
blend aggregate with asphalt one batch at a time in a separate mixer; drum mix plants
dry the aggregate and blend aggregate with asphalt in a continuous process.
4.1.1 Batch Plant Operations and Components
Batch plants get their name from the fact that, during operation, they produce hot mix
asphalt in batches, producing one batch at a time, one after the other. The size of a batch
varies according to the capacity of the plant's pugmill (the mixing chamber where
aggregate and binder are blended together).
26
27
Certain basic operations are common to all batch plants. They are:
Aggregate storage and cold feeding,
Aggregate drying and heating,
Screening and storage of hot aggregates,
Storage and heating of asphalt binder.
Measuring and mixing of asphalt binder and aggregate.
Loading of finished hot-mix.
Figure 4.1 Major Batch Plant Components
Figure 4.1 illustrates the major components of a typical asphalt batch plant. The
process of batch plants may be summarized as follows:
28
Cold (unheated) aggregates stored in the cold bins (1) are proportioned by cold-feed
gates (2) on to a belt conveyor or bucket elevator (3), which delivers the aggregates to
the dryer (4), where they are dried and heated. The baghouse (5) removes undesirable
amounts of dust from the dryer exhaust. Remaining exhaust gases are eliminated
through the plant exhaust stack (6). The dried and heated aggregates are delivered by
hot elevator (7) to the screening unit (8) equipped with a scalping screen to remove any
over sized material. This oversized material is deposited into a reject chute (15) for
disposal. The material is then sized into different sized fractions and deposited into
separate hot bins (9) for temporary storage. When needed, the heated aggregates are
measured in controlled amounts into the weigh box (10). The aggregates are then
dumped into the mixing chamber or pugmill (11), along with the proper amount of
mineral filler, if needed, from mineral filler or baghouse fines storage (12). If the plant is
capable of producing recycled mixes then a RAP Bin and conveyor (16) is needed.
Heated asphalt binder from the hot asphalt binder storage tank (13) is pumped into the
asphalt binder weigh bucket (14) which weighs the asphalt binder prior to delivering it
to the mixing chamber or pugmill where it is combined thoroughly with the aggregates,
baghouse fines or mineral filler if used. From the mixing chamber the asphalt hot-mix is
deposited into a waiting truck or delivered into storage silos or surge bins (17).
When anti-strip additives are introduced at the plant site an additive storage tank (18)
is required with a totalizing flowmeter (19), which is not capable of being reset,
mounted in the additive feed line just prior to introduction into the binder feed line
4.1.2 Drum Mix Plant Operations and Components
Drum mixing is a relatively simple process of producing asphalt hot-mix. The
mixing drum from which this type of plant gets its name is very similar in appearance to
a batch plant dryer drum. The difference between drum-mix plants and batch plants is
that, in the more conventional drum-mix plants the aggregate is not only dried and
heated within the drum, but also mixed with the asphalt binder. However, there are
some more recent model drum mix plants that introduce the asphalt binder outside the
29
drum. The addition of a coater box, which is a pugmill type device, located at the
discharge end of the drum allows the asphalt binder to be added into the coater box
instead of into the drum. Still other "double barrel" type drum mix plants will add the
asphalt binder between an inner and outer drum. The basic concept of all these types is
the same though a continuous mixing process as compared to the mixing of batches at
batch plants. There are no gradation screens, hot bins, or weigh hoppers in a drum-mix
plant. Aggregate gradation is controlled at the cold feed and by the gradations of the
individual aggregates being used.
Figure 4.2 Basic Drum Mix Plant
Referring to Figure 5-3, the following is a brief, general description of the sequence
of processes involved in a typical drum-mix plant operation:
Aggregates are deposited in the cold feed bins (1) from which they fed in exact
proportions cold feeders (2) across a vibratory scalping screen (3) on to a cold-feed
30
conveyor (4). An automatic aggregate weighing system or weigh bridges (5) monitors
the amount of aggregate flowing into the drum mixer (6). The weighing system is
interlocked with the controls on the asphalt binder storage pump which draws asphalt
binder from a storage tank (7) and introduces it into either the drum, coater box, or
between an inner and outer drum, where asphalt and aggregate are thoroughly blended
by a mixing action. A dust collection system baghouse (8) captures excess dust escaping
from the drum. From the drum, the hot-mix asphalt concrete is transported by hot-mix
conveyor (9) to a surge bin or silo (10) from which it is loaded into trucks and hauled to
the paving site. All plant operations are monitored and controlled from instruments in
the control room.
4.2 Transportation
Laydown temperature, aggregate segregation and temperature differentials are strictly
related with transportation, therefore mix transportation is very important on
construction quality. Transportation process includes loading the HMA to the truck,
transporting within the truck and unloading at the paving side.
There are two important points when loading the vehicle at the production facility;
firstly the truck bed should be cleaned and coated with lubricant or non-petroleum based
materials to prevent the HMA from sticking to the truck bed; secondly multiple dump
loading should be used to prevent large-sized aggregates rolling down the sides of the
cone of dumped material, as illustrated in Figure 4.3 to Figure 4.4
31
Figure 4.3 Incorrect truck – loading sequence
Figure 4.4 Correct truck – loading sequence
Keeping mixture hot during transportation is important because the mixture will tend
to cool due to the temperature differences between surrounding environment and HMA.
This cooling process will start from surface of the loaded HMA by developing a cool
thin crust that surrounds a hotter core. To avoid from cooling and formation of crust,
truck beds should be insulated and a large enough water-resistant tarpaulin should cover
the top of the load.
32
Figure 4.5 Infrared picture of an HMA storage silo loading a truck showing the hot uniform temperature of
the mix and infrared picture of a truck dumping HMA showing the cold surface layer crust (blue) and the
hot inner mass (red).
In most cases, truck transport appears to cool only the surface of the transported
HMA mass, however this cool surface crust can have detrimental effects on overall mat
quality if not properly dealt with. Actions such as reducing transport time, insulating
truck beds or tarping trucks can decrease HMA surface cooling rate. Additionally, since
the majority of the HMA mass is still at or near its original temperature at loading,
mixing the crust and interior mass together at the paving site (“remixing”) will produce a
uniform mix near the original temperature at loading.
The mix is unloaded by raising the truck bed and letting the payload slide down the
bottom of the bed into the hopper. The truck bed should be raised slightly before the
tailgate is opened. When the bed is raised it should not contact the paver, because if it
contacts with the paver, the screed tow point may change and smoothness of the mat
would change. Once the paver and truck are in contact paver should move it forward like
a motionless truck or like using truck hitches located on or near the push rollers.
4.3 Surface Preparation
In this section only the preparation of existing surfaces for hma over hma will be
taken in consideration.
33
Tack coat is applied on the existing pavement to bond the overlay to the existing
pavement surface. Generally it is a light application of an asphalt material to an existing
pavement or asphalt base course immediately prior to placing the next pavement layer or
course. Strong bond between pavement layers is important for transferring radial tensile
and shear stresses into pavement to behave as a whole structure. A surface without good
bond between the existing surface and the new overlay may show the manner of
debonding, mat slippage, and potentially fatigue cracking, which will cause reduced
pavement life.
Before application all materials like dust, loose aggregate, soil, leaves, or any other
foreign material deposited on the existing surface should be removed to prevent them
interfere with the adhesion of the tack coat. Cleaning may be done by the help of
brooming, handscraping, and perhaps power blading of heavy accumulations. There
should be no visible, flowing water on the surface and all cracks in an existing pavement
surface should be sealed.
The three essential requirements of a tack are;
The application of the asphalt material is required to be very thin,
The material must uniformly cover the entire surface of the area to be paved,
The material must be allowed to break (cure) before the HMA is applied.
The tack coat is applied by pressure distributor to the cleaned surfaces uniformly. All
nozzles on the distributor should be functioning to prevent streaking or puddling.
Streaking is usually caused by nozzles set at the wrong angle or having the spray bar at
the wrong height therefore nozzles should all be set at the same angle with the bar so the
spray from one does not interfere with adjacent nozzles. A proper height above the
pavement surface provides a double or triple lap of the liquid asphalt material.
34
Figure 4.6 Nozzles of the distributor when spraying double or triple lap of the liquid asphalt material.
Special attention should be given to the edges to assure proper coverage of the full
width intended.
Figure 4.7 High and low spray bar application.
35
Before placing HMA on the tack coat, time is required for evaporation of water in
asphalt emulsions. Time needed for evaporation will depend on the type and grade of the
emulsion used, environmental conditions, application rate and temperature of the
existing pavement surface. The color of the emulsion turns from brown to black and it
breaks.
There is some controversy about whether HMA can be placed on top of an asphalt
emulsion before the emulsion is set—while some water is still retained on the pavement
surface. There is even more controversy about whether HMA can be placed on top of an
asphalt emulsion before it has broken—while the asphalt cement and water are still
combined. In the past, it was generally believed that the emulsion should be completely
set before new mix is laid on top of the tack coat material. Experience has shown,
however, that new HMA can usually be placed on top of an unset tack coat and even
over an unbroken tack coat emulsion with no detrimental effect on pavement
performance; the bond will still be formed. Indeed, in Europe the emulsion tack coat is
often applied to the pavement surface underneath the paver—from a spray bar located
just behind the paver drive tires or tracks and just before the head of HMA in front of the
paver screed. With this tack coat application point, the emulsion will be unbroken when
the mix is laid on top of it, but the emulsion will break immediately upon contact with
the new HMA. The water, 0.36 l/m2 (0.08 gal/yd2), typically will evaporate and escape
as steam through the loose hot mix. There is not enough water to lower the mat
temperature significantly. (U.S.Army Corps., 1991, p 7-12)
4.4 Mix Placement
Mix placement includes complex asphalt paver operations and simple manual
shoveling to place the delivered HMA on the desired surface to obtain the desired width,
grade, cross slope, thickness and a homogeneous mat texture.
36
Basically there are two types of Asphalt Pavers which are tracked (crawler) and
rubber-tire (wheeled) pavers and the function of all pavers can be summarized as; HMA
received from a transport vehicle, stored in hopper, carried to the rear of the machine by
conveyors, distributed transversely by a pair of augers, leveled on the prepared surface
and compacted by a screed. This operation is comprised of two basic units; the first unit
is the tractor, which provides the driving force to move machine forward and the energy
of the running mechanical system; the second unit is the screed unit, which levels and
pre-compacts the hot mix asphalt.
Figure 4. 8 Basic components of a asphalt paver.
4.4.1 Tractor Unit
The tractor unit includes the material feed system, which receives the asphalt mix at
the front of the paver, carries it to the back of asphalt paver and spreads it out across the
width of the screed. Tractor unit consists of following components; the truck push
rollers, hopper, slat conveyors, material flow gates (usually), and a pair of augers.
37
Figure 4.9 Basic components of a Tractor unit.
Operation of the tractor, and specifically the material feed system, can have
significant effects on overall construction quality and thus long-term pavement
performance. Although there are many detailed operational concerns, the two broad
statements below encompass most of the detailed concerns:
HMA must be delivered to maintain a relatively constant head of material in front of
the screed. This involves maintaining a minimum amount of HMA in the hopper,
regulating HMA feed rate by controlling conveyor/auger speed and flow gate openings
(if present), and maintaining a constant paving speed. As the next section will discuss, a
fluctuating HMA head in front of the screed will affect the screed angle of attack and
produce bumps and waves in the finished mat.
The hopper should never be allowed to empty during paving. This results in the
leftover cold, large aggregate in the hopper sliding onto the conveyor in a concentrated
mass and then being placed on the mat without mixing with any hot or fine aggregate.
38
This can produce aggregate segregation or temperature differentials, which will cause
isolated low mat densities. If there are no transport vehicles immediately available to
refill the hopper it is better to stop the paving machine than to continue operating and
empty the hopper (TRB, 2000).
4.4.2 Screed Unit
The screed unit establishes the thickness of the asphalt layer and provides the initial
texture to the new surface. In addition, the screed provides some level of density to the
material being placed through the vibratory action of the screed or tamping bars.
Because the screed unit determines the initial texture of the mix placed, this unit is the
most important part of the paver.
Basic screed components can be summarized as follows;
Screed plate: The flat bottom portion of the screed assembly that flattens and
compresses the HMA.
Screed angle (angle of attack): The angle the screed makes with the ground surface.
Strike-off plate: The vertical plate just above the leading edge of the screed used to
strike off excess HMA and protect the screed’s leading edge from excessive wear.
Screed arms: Long beams that attach the screed to the tractor unit
Tow point: Point at which the screed arm is attached to the tractor unit
Depth crank: The manual control device used to set screed angle and ultimately, mat
thickness.
39
Screed heater: Heaters used to preheat the screed to HMA temperature. HMA may
stick to a cold screed and cause mat tearing. After the screed has been in contact with
the HMA for a short while (usually about 10 minutes) its temperature can be maintained
by the HMA passing beneath it and the heater can be turned off. If the screed is
removed from contact with HMA for an extended period of time, it may need to be pre-
heated again before resuming paving.
Screed vibrator: Device located within the screed used to increase the screed’s
compactive effort. Screed compaction depends upon screed weight, vibration frequency
and vibration amplitude.
Screed extensions: Fixed or adjustable additions to the screed to make it longer.
Basic screed widths are between 2.4 m and 3.0 m. However, often it is economical to
use wider screeds or adjustable width screeds. Therefore, several manufacturers offer
rigid extensions that can be attached to a basic screed or hydraulically extendable
screeds that can be adjusted on the fly.
Figure 4.10 Screed components
40
4.4.3 Forces Acting On the Screed
During mix placement two main forces acts on screed; the towing force which is
provided by the tractor and depends on the paver speed; the resistance force of the of
head of material against screed which depends on the amount and type of the mix.
The angle between the bottom plate of the screed and the surface being paved is
defined as “angle of attack” and controlled by rising or lowering the level of the tow
point. When one of the forces which explained above paragraph change, the screed will
rise or fall to obtain equilibrium of forces and this will result in changing the thickness
of the mat.
Today’s pavers act upon six basic forces. First force is Towing force which is
provided by the tractor and exerted at the tow point. Second Force is resistant of HMA
head against towing force which is controlled by the material feed rate and HMA
characteristics. Third one is the Weight of the screed acting vertically downward. Fourth
one is a function of HMA characteristics and screed weight which is resistive upward
vertical force from the material being compacted under the screed. Fifth one is
Additional downward force applied by the screed’s tamping bars or vibrators and
controlled by vibratory amplitude and frequency or tamping bar force. The last one is
Frictional force between the screed and the HMA under the screed and controlled by
HMA and screed characteristics.
41
Figure 4.11 Screed forces acting on screed.
4.4.4 Factors Affecting Mat Thickness and Smoothness
In paving operations the screed angle is adjusted to control mat thickness. The
interaction of paver speed, material feed rate and tow point elevation determine the
screed position therefore changing anything on the paver that affects equilibrium forces
will change mat thickness.
If the amount of HMA in front of the screed increases, screed angle will increase to
restore equilibrium or when paver speeds up and all other forces on the screed remain
constant, the screed angle which decreases mat thickness should decrease to restore
equilibrium. Similarly, as the tow point rises in elevation, the screed angle increases and
results in a thicker mat.
4.5 Compaction
Compaction is the process by which the HMA is compressed and reduced in volume
by the help of external forces. This process forces the asphalt-coated aggregates in the
mix get closer, thus aggregate interlock and interparticle friction increases. As a result of
42
this process, air voids reduces, the unit weight or density of the mix increases. If
compaction is not performed adequately, it results in pavement failures like rutting,
instability, increase in oxidation or aging or moisture damage, low-temperature cracking,
etc...
The volume of air has serious effects on long-term pavement performance. An
approximate "rule-of-thumb" is for every 1 percent increase in air voids (above 6-7
percent), about 10 percent of the pavement life may be lost (Linden et al., 1989). As a
general assumption dense graded mixes should not exceed 8 percent nor fall below 3
percent air voids during their service life. High air void content (above 8 percent) or low
air void content (below 3 percent) can cause the following pavement distresses;
Decreased stiffness and strength
Reduced Fatigue Life.
Accelerated Aging/Decreased Durability.
Raveling.
Rutting.
Moisture Damage.
4.5.1 Stages of compaction
Paver screed, steel wheeled roller and pneumatic tire roller are the three basic
equipment that compact the HMA by two principal means:
By applying its weight to the HMA surface and compressing the material underneath
the ground contact area. Since this compression will be greater for longer periods of
43
contact, lower equipment speeds will produce more compression. Obviously, higher
equipment weight will also increase compression.
By creating a shear stress between the compressed material underneath the ground
contact area and the adjacent uncompressed material. When combined with equipment
speed, this produces a shear rate. Lowering equipment speed can decrease the shear
rate, which increases the shearing stress. Higher shearing stresses are more capable of
rearranging aggregate into more dense configurations.
These two means of densifying HMA are often referred to collectively as
“compactive effort”. This section discusses the paver screed, the steel wheeled roller
(both static and vibratory) and the pneumatic tire roller as they apply to HMA
compaction”
Compaction process can be defined in five stages;
Screed
Initial compaction
Main compaction
Finish rolling
Traffic
Screed;. The screed is the first device used to compact the mat and may be operated
in the vibratory mode. According to the type and model of asphalt pavers 75 to 85
percent of theoretical density is obtained during this stage.
Initial compaction; According to “Yollar Fenni Şartnamesi” initial compaction should
start immediately after mix placement. Static tandem rollers (if necessary pneumatic tire
44
rollers) should be used with at least two passes. However experiences show that
pneumatic tire rollers are more suitable to prevent micro cracks during the compaction
of wearing course of HMA. The breakdown roller is the first roller behind the screed
and therefore, generally affects the most density gain of any roller in the sequence.
Breakdown rollers can be of any type but are most often vibratory steel wheel and
sometimes pneumatic tire.
Main compaction; the intermediate roller is used behind the breakdown roller if
additional compaction is needed. Pneumatic tire rollers are sometimes used as
intermediate rollers because they provide a different type of compaction (kneading
action) than a breakdown steel wheel vibratory roller. This can help further compact the
mat or at the very least, rearrange the aggregate within the mat to make it receptive to
further compaction.
Finish rolling; .The finish roller is last in the sequence and is used to provide a
smooth mat surface. Although the finish roller does apply compactive effort, by the time
it comes in contact with the mat, the mat may have cooled below cessation temperature.
Static steel wheel rollers are almost always used as finishing rollers because they can
produce the smoothest surface of any roller type.
Traffic; after the rollers compact the mat to the desired density and produced the
desired smoothness, the new pavement is opened to traffic. Traffic loading will provide
further compaction in the wheel paths of a finished mat. For instance, a mat compacted
to eight percent air voids and then opened to heavy traffic (e.g., an interstate freeway)
may further compact to about three to five percent air voids in the wheelpaths over time.
4.5.2 Factors Affecting Compaction
An adequate compaction process is influenced by numerous factors that can be
summarized in four major titles: Material properties, compaction equipment, lay-down
site conditions and construction factors.
45
Table 4.1 Factors Affecting Compaction
Material Properties Compaction Equipments
Lay Down Site Conditions Construction Factors
Aggregate • Gradation • Size • Shape • Fractured Faces • Volume
Asphalt Binder • Chemical Properties • Physical Properties • Amount
Mixture Properties • Workability • Lay-down Temperature • Moisture Content
Rollers • Type • Number • Speed And
Timing • Number Of
Passes • Lift Thickness
Screed • Initial
compaction
Temperature • Ground Temperature • Air Temperature • Wind Speed • Solar Flux
Other • HMA Production Temperature • Haul Distance • Haul Time • Foundation Support
Aggregates
The nature of the aggregate particles and aggregate gradation in the mix effects on the
compactibility or stiffness of an HMA mixture. Surface texture, particle shape, and
number of fractured faces are the major properties of coarse aggregate that effects
adequate level of compaction. Angular particles will increase the resistance to
densification as a consequence of this more compactive effort will be needed. In a
similar manner to this aggregates that have a rough surface texture are more difficult to
compact than aggregates with a smooth surface texture.
Mixes that contain an excess of midsize fine aggregate [between the 0.60- and 0.3-
mm ( No. 30 and No. 50) sieves or between the 0.425- and 0.180-mm ( No. 40 and No.
80) sieves] also are difficult to compact because of their lack of internal cohesion. These
mixes tend to displace laterally rather than compress vertically. In addition, dust content
[amount of aggregate passing the 0.75-mm (No. 200) sieve] affects the compactive
effort needed. A mix designed with a high dust content will generally be more difficult
46
to compact than one with a lower dust content, depending on the angularity and fineness
of the dust particles. (Geller, 1984)
Midsize fine aggregate (between the 0.60 and 0.30-mm (No. 30 and No. 50) sieves).
High amounts of midsize fine, rounded aggregate (natural sand) cause a mix to displace
laterally or shove under roller loads. This occurs because the excess midsize fine,
rounded aggregate results in a mix with insufficient voids in the mineral aggregate
(VMA). This gives only a small void volume available for the asphalt cement to fill.
Therefore, if the binder content is just a bit high it completely fills the voids and the
excess serves to (1) resist compaction by forcing the aggregate apart and (2) lubricate
the aggregate making it easy for the mix to laterally displace. (U.S.Army Corps., 1991, p
7-12)
Asphalt Cement
The grade and amount of asphalt cement used in a mix affect the ability to densify the
mix. An asphalt cement with lower in penetration will generally cause a stiffer mix at a
given mix temperature, which will be more resistant to compaction. So the stiffer mixes
need more compactive effort to achieve a given density level. Asphalt binder lubricates
the aggregate during compaction and therefore, mixes with low asphalt content are
generally difficult to compact because of inadequate lubrication, whereas mixes with
high asphalt content will compact easily but may shove under roller loads.
The degree of hardening (aging) that occurs in asphalt binder during manufacture of
the mix also affects the compactibility of the mix. Various asphalts age differently
during the mixing process, depending, in part, on the chemical properties of the asphalt
cement. Aging is also influenced by the type and operating characteristics of the HMA
plant—more hardening will typically occur when a drum-mix plant is operating at
partial capacity than when it is operating at full capacity. Moreover, higher
47
manufacturing temperatures generally produce somewhat stiffer mixes. ((U.S.Army
Corps., 1991, p 9-14)
Mix Properties
In addition to aggregate and binder properties, workability and compactive effort
needed for compaction of a mixture is influenced by lay down temperature. When
temperature decreases binder becomes more viscous and resistant to deformation for a
certain compactive effort. The higher lay down temperature results in lower compaction
effort till a certain temperature. If the initial mix temperature is too high the mix will
tend to move laterally thus it will be hard to compact till a certain temperature which
should be determined according to on the mixture properties.
The fluids content of the mix also affects the compactive effort needed. The fluids
content is the sum of the asphalt cement content and the moisture content of the mix. If
the amount of moisture in the mix from the plant is high (greater than 0.2 percent, by
weight of mix), the extra fluids content will act like asphalt binder and may make the
mix unstable and difficult to compact. Thus, the moisture content of plant-produced mix
should be measured regularly. Most specifications require that moisture content be less
than 0.5 percent, by weight of mix, when the mix is discharged from the plant. If the mix
characteristics are marginal, however, a residual moisture content of as little as 0.2
percent may significantly alter the tenderness of the mix, and therefore its
compactibility. (U.S.Army Corps., 1991, p. 9-36)
4.5.3 Compaction Equipment
As mentioned before Paver screed, steel wheeled rollers and pneumatic tire rollers are
the three major equipment that is used for compaction.
The paver screed
48
Steel wheel rollers
Vibratory steel wheel rollers
Pneumatic tire rollers
Paver Screed
Device located within the screed used for screed’s compactive effort. Screed
compaction depends upon screed weight, vibration frequency and vibration amplitude.
Steel Wheel Rollers
Steel wheel rollers can have two or three drums. These rollers have various weights
and configurations and can be examined in two types which are static steel wheel rollers
and vibratory steel wheel rollers.
Static steel wheel rollers, range in weight from 2 to 18 and have compression drums
that vary in diameter from approximately 1.0 m to more than 1.5 m. These rollers are
usually used after asphalt paver as a breakdown roller during the initial compaction. The
gross weight of them is usually modified by adding either sand or water to increase
compactive effort. Steel wheel rollers spray water from a transverse bar that placed
upside of the drum to avoid sticking of asphalt cement to steel wheels.
Figure 4.12 Two different types of Steel Wheel Rollers.
49
For this type of roller, both the gross weight of the machine and the contact area of
the drums with the mix are important in determining the compactive effort applied by
the roller to the surface of the new mat. Effective contact pressure, in terms of
kilopascals (kPa) [pounds-force per square inch (psi)] over the contact area, is the key
variable for this type of equipment and is dependent on the depth of penetration of the
drums into the mix: the greater the depth of penetration, the greater is the contact area
and so the less is the contact pressure. Thus on the first pass of the roller, when the
indentation of the drums into the mix is the greatest, the roller exerts less compactive
effort on the mix. On subsequent passes as the mix becomes denser, the drums penetrate
to a lesser degree, and the compactive effort of the roller is increased.
Vibratory Steel Wheel Rollers
Vibratory Steel Wheel Rollers are the steel wheel rollers that equipped with vibratory
drums. They apply two types of compactive effort to the HMA which are static weight
and dynamic force. The dynamic force derived from the vibration of roller drum is
produced by a rotating eccentric weight located inside the drum which is proportional to
the eccentric moment of the rotating weight and the speed of rotation.
As a general rule-of-thumb, a combination of speed and frequency that results in 3 -
3.5 impacts per meter (10 - 12 impacts per foot) is good. At 3000 vibrations/minute that
gives a speed of 4.5 - 5.5 km/hr (2.8 - 3.4 mph).
When density is difficult to quickly achieve with a vibratory steel wheel roller, the
tendency may be to increase vibratory amplitude to increase compactive effort.
However, high amplitude is only advisable on stiff mixes or very thick lifts that can
support the increased amplitude without fracturing the constituent aggregate particles.
For typical mix types and lift thicknesses a better solution is usually to maintain low
amplitude vibrations and increase the number of roller passes at low amplitude.
The pneumatic tire Rollers
50
The pneumatic tire rollers perform kneading action on HMA by pneumatic tires.
They are usually operated in the intermediate roller position, behind a vibratory or static
steel wheel breakdown roller and in front of a static steel wheel finish roller. Pneumatic
rollers are sometimes used for initial rolling of the mix, and occasionally for finish
rolling.( (U.S.Army Corps.,1991, p 7-12)
Typically pneumatic tire rollers provide 4,5,6 or 7 tires on the front of the roller and
3,4,5 or 6 tires on the rear of the roller. The inflation pressure of tires can be varied to
obtain desired contact pressure on the mat. If these rollers are to be used for compaction
it is recommended that adjust the tire inflation pressures as high as the behavior of the
HMA will permit without severe rutting.
Kneading action between the tires that tends to realign aggregate within the HMA
results in both advantages and disadvantages when compared to steel wheel rollers:
Advantages (Brown, 1984)
They provide a more uniform degree of compaction than steel wheel rollers.
They provide a tighter, denser surface thus decreasing permeability of the layer.
They provide increased density that many times cannot be obtained with steel
wheeled rollers.
They compact the mixture without causing checking (hairline surface cracks) and
they help to remove any checking that is caused with steel wheeled rollers.
51
Disadvantages
The individual tire arrangement may cause deformations in the mat that are difficult
or impossible to remove with further rolling. Thus, they should not be used for finish
rolling.
If the HMA binder contains a rubber modifier, HMA pickup (mix sticking to the
tires) may be so severe as to warrant discontinuing use of the roller.
In summary, pneumatic tire rollers offer a slightly different type of compaction than
steel wheel rollers. The arrangement of multiple tires on both axles serves to both
compress and kneed the mat, which may or may not be advantageous over steel wheel
rollers.
CHAPTER FIVE
5 TYPES OF PAVEMENT FAILURES AND THEIR CAUSES
Failures frequently occur in bituminous pavements because of structure of the
bituminous mixtures, inadequate choice of design method and materials, local factors
such as traffic and climatic conditions, inadequate quality control or poor construction.
5.1 Pavement Performance
Current concepts of pavement performance in USA and other developed countries
include some consideration of functional performance, structural performance, and
safety.
The structural performance of a pavement relates to its physician condition; for
example; occurrence of cracking, faulting, raveling or other conditions, which would
adversely affect the load-carrying capability of the pavement structure and would require
maintenance (AASHTO, 1993).
The serviceability of a pavement is expressed in term of the present serviceability
index (PSI). The PSI is based upon a rating scale that ranges from a through 5 designates
the condition of the pavement at any instant of time. A rating of 5 indicates a “perfect”
pavement, whereas a rating (Uluçaylı, 2001).
The PSI is obtained from measurements of roughness and distress; for example,
cracking, patching and rut depth (flexible), at a particular time during the service life of
the pavement. Roughness is the dominant factor in estimating the PSI of a pavement.
Thus, a reliable method for measuring roughness is important in monitoring the
performance history of pavements (AASHTO, 1993).
52
53
5.2 Types of Failures
Structural failure and functional failure are two different types of failures that have
been occurring in the pavement. Structural failures include a collapse of the pavement
structure or a break down of one or more pavement components of such magnitude to
make the pavement incapable of sustaining the loads imposed upon its surface. In
functional failures the pavement will not carry out its function without causing
discomfort to passengers.
Functional failure may recover by resurfacing upper layer of the pavement. However,
the structural failure may require complete rebuilding of the pavement structure.
The distresses occurring in the flexible pavements can be grouped as;
Table 5.1 The distresses in flexible pavements.
Deformations; Crackings; Disintegrations;
-Rutting -Alligator Cracking -Stripping
-Upheaval -Edge Cracking -Bleeding or Flushing
-Depression -Fatigue cracking, -Polishing
-Distortion -Low temperature cracking -Raveling and Weathering
-Swelling -Reflection cracking -Pot-holes
-Shrinkage cracking -Lack of Bond (Peeling)
5.3 Causes of Failures
The factors having adverse effects on pavement life may be categorized as;
Destructive effects of traffic; Overload including excessive gross loads, high
repetitions of loads, and high pressures.
54
Disintegration of the paving materials, due to the freezing and thawing and/or wetting
and drying.
Lack of adequate supporting capacity of base and/or subbase course
Destructive effects of weathering; Climatic conditions as well as environmental
conditions which cause surface irregularities and structural weakness to develop,
The two main reasons of deformations in flexible pavements can be summarized as;
deformations because of weak asphalt mixture and deformation because of subgrade.
There are three main reasons of cracking; these are stood in line; Fatigue cracking; and
low temperature cracking with in the bituminous layers, and cracking because of the
lack of supports of tensile stresses. General categories and causes of pavement distresses
are shown in Table 5.2.
Table 5.2 General Categories of Types of Asphalt Pavement Distress (AASTHO, 1986)
Distress Type Primarily TralTic Load Caused
Primarily Climate/Material Caused
1. Alligator or Fatigue Cracking x 2. Bleeding x 3. Block Cricking x 4. Corruption x 5. Depression x 6. Joint Reflection Cracking from PCC Slab x 7. Lane/Shoulder Drop-off or Heave x 6 Lane Shoulder Separation x 9. Longitudinal and Transverse Cracking x 10. Patch Deterioration x 11. Polished Aggregate x 12. Pat holes x 13. Pumping and Water Bleeding x x 14. Raveling and Weathering x 15. Rutting x 16. Slippage Cracking x 17. Swell x
55
5.4 Bituminous Mixture Behavior
When a wheel load is applied two primary stresses is occurred in hot mix asphalt.
These stresses can be summarized as; vertical compressive stress within the bituminous
layer and horizontal tensile stress at the bottom of the bituminous layer. When the
amount and repetition of these stresses become higher, these stress results in pavement
distresses. The hot mix asphalt must be internally resilient to resist to compressive
stresses and prevent permanent deformation within the mixture. In the same manner, the
materials must also have tensile stresses at the base of the bituminous layer, and also be
resilient to withstand many load applications without fatigue cracking.
5.5 Permanent Deformations
Rutting (Wheel Path) is the most common form of permanent deformation. Rutting
may be caused by many reasons (e.g., underlying HMA weakened by moisture damage,
abrasion, traffic densification), but these causes may be summarized in two principal
causes.
In one case, the rutting is caused by too much repeated stress being applied to the
subgrade (or subbase or base) below the asphalt layer (Figure 5.1). Although stiffer
paving materials will partially reduce this type of rutting, it is normally considered a
structural problem rather than a materials problem. Essentially, there is not enough
pavement strength or thickness to reduce the applied stresses to a tolerable level. A
pavement layer that has been unexpectedly weakened by the intrusion of moisture may
also cause it. The deformation occurs in the underlying layers rather than in the asphalt
layers. (Asphalt Institute, 1996)
56
Figure 5.1 Rutting from Weak Subgrade (V Profile) (Asphalt Institute, 1996)
This is referred to an structural rutting, and the resulting ruts are wide and not have
humps to their sides (V profile).
The second mechanism is the result of individual deformation of the bituminous
courses due to load-induced stresses exceeding the stability threshold of the material.
This called flow (or instability) rutting, and the resulting ruts have humps to their sides
(W profile under the action of dual tires, and asymmetric under the action of wide-based
single tires). Flow ruts are most often formed on ascending gradients, on junction
approaches and in bends, i.e. where heavy lorries have to reduce speed and tangential
stresses in the tire-pavement contact area are higher (Verstraeten, 1994, p.14).
This type of rutting has to do with mix design rather than structural design. The
relevant factors are the characteristic of the various constituents; their proportions in the
mix, and laying.
The type of rutting of most concern to asphalt mix designers is deformation in the
asphalt layers. This rutting results from an asphalt mixture without enough shear
strength to resist repeated heavy loads (Figure.4.2). A weak mixture will accumulate
small, but permanent, deformations with each truck pass, eventually forming a rut
characteristic by a downward and lateral movement of the mixture. The rutting may
57
occur in the asphalt surface course, or the rutting that shows on the surface may be
caused by a weak underlying asphalt course.
Fig.5.2. Rutting from Weak Mixture (W Profile) (Asphalt Institute, 1996)
Rutting of a weak mixture typically occurs during the summer under higher pavement
temperatures. While this might suggest that rutting is solely an asphalt cement problem,
it is more correct to address rutting by considering the combined resistance of the
mineral aggregate and asphalt cement.
Since rutting is an accumulation of very small permanent deformations, one way to
increase mixture shear mixture shear strength is to use not only a stiffer asphalt cement
but one that also behaves more like an elastic solid at high pavement temperatures.
Then, when a load is applied, the asphalt cement will act like a rubber band and spring
back to its original position rather than deforming.
Another way to increase the HMA shear strength is by selecting an aggregate that has
a high degree of internal friction-one that is cubical, has a rough surface texture, and is
graded to develop particle-to-particle contact. When a load is applied to the mixture, the
aggregate particles lock tightly together and function more as a large, single, elastic
stone. As with the asphalt cement, the aggregate will act like a rubber band and spring
back to its original shape when unloaded. In that way, no permanent deformation
accumulates (Asphalt Institute, 1996)
CHAPTER SIX
6 LABORATORY TESTS
6.1 Aggregate and Bitumen Tests Used In Design
The type of aggregate used in mix designs are basalt aggregate which was supplied
from Şaphane Basalt Quarry in Uşak and limestone which was supplied from Sivaslı
Limestone quarry in Uşak. The bitumen used in design was a product of Aliağa Refinery
which classified as AC 50 – 70. To be sure of the hardness of the bitumen penetration
test is done. Also specific gravity of bitumen is tested again to be used in Marshall Mix
design.
6.1.1 The Los Angeles Abrasion Test
The samples are washed ,dried in oven to a constant mass at 105 °C, separated into
individual size fractions, and recombined to the grading most nearly corresponding to
the range of sizes in the aggregate as originally furnished.
Figure 6.1 Los Angeles Abrasion Test Machine
The samples are placed in the Los Angeles testing machine and rotated at a speed of
30 to 33 rpm for 500 revolutions. The samples are discharged from the machine and
58
59
separated on a No. 12 sieve (1.70 mm). The aggregates coarser than the No. 12 (1.70
mm) sieve are washed, oven-dried to a constant mass at 105 °C and final weight is
recorded after cooling. The difference between the original weight and the final weight
of the test sample as a percentage of the original weight is calculated as follows;
L.A. Abrasion Loss (%) = (A – B) / A x 100
A = Original Weight of the sample,
B = Final Weight of the sample.
Table 6.1 Results of Los Angeles Abrasion tests
Basalt Limestone
A Sample Weight 5000 5000
B Retrained on 1.7 mm sieve 4148 3630
(A-B) / A x100 Los Angeles Abrasion 17.04% 27.40%
6.1.2 The Crushing Test
The sample is broken into chips passing through 12.5 mm sieve and retrained on 10
mm sieve, dried in oven to a constant mass at 105°C and left to cool in room
temperature. The material is placed in steel cylinder by layers up to one-third height and
tamped twenty-five times by the plunger. The plunger is placed on the sample and forty
tones applied at a uniform rate of 4 tones per minute. The crushed aggregate is removed
from and sieved on 2.36 mm sieve. The percentage passing through 2.36 mm sieve is
calculated and recorded as crushing ratio.
The crushing test results of aggregates are shown in Table 6.2
60
Table 6.2 Results of Basalt Aggregate’s Crushing Tests
Test No 1 2 Sample Weight A 2732 2739 Retrained on 2.36 mm Sieve, g B 2238 2262 Percent Passing % C 18,1% 17,4% Aggregate Crushing Ratio (C1 + C2)/2 17,7%
Table 6.3 Crushing Test Results of Limestone Aggregates
Test No 1 2 Sample Weight A 2738 2731 Retrained on 2.36 mm Sieve, g B 2157 2186 Percent Passing % C 21,2% 20,0% Aggregate Crushing Ratio (C1 + C2)/2 20,6%
6.1.3 The Stripping Test
Aggregate samples that are passing through 9.75mm sieve and retrained on 4.75 mm
sieve are oven dried at 110°C, mixed with bitumen till the aggregate surfaces are coated
with bitumen homogeneously and put in oven for 24 hours at 60°C. The aggregates that
coated with bitumen are taken from oven and immersed in water bath at 60°C for 24
hours. The percentage of stone surface after specified period is estimated.
Because of the basalt aggregate’s chemical composition, the antistripping agent
Iterline 400-S is used in mix designs. The stripping test results done with aggregates that
is used in mix design can be seen in Table 6.4.
Table 6.4 Stripping test results of aggregates
TEST CONDITIONS Without Antistripping
Agent With Iterline 400-S
Aggregate Size 9.5 mm / 4.75 mm 9.5 mm / 4.75 mm Weight of Aggregate 50 ± 0.5 g 50 ± 0.5 g Weight of Bitumen 2.5 ± 0.1 g 2.5 ± 0.1 g Heating Temperature of Agregate 110 - 150 C 110 - 150 C Heating Time of Aggregate 1 hour 1 hour Time Passed in oven and water 60 C (1 hour) 60 C (1 hour) The Ratio of the unstripped surface to the whole surface 35 - 40 % 65 - 70 %
61
6.1.4 The Sieve Analysis Test
Aggregates samples which are separated into sizes 3/4 inch – 3/8 inch (19 mm – 9.5
mm), 3/8 inch – No.4 (9.5 mm – 4.75 mm), and minus No.4 (4.75 mm) were supplied
from the Şaphane Basalt Quarry and Sivaslı Limestone Quarry in Uşak.
The samples with size of 3/4 inch – 3/8 inch(19 mm – 9.5 mm)and 3/8 inch – No.4
(9.5 mm – 4.75 mm) are split to the correct size, the total dry weight is determined. The
sieves are nested in order of decreasing size of openings from the top to bottom. A pan
placed below sieves, after pouring specimens the lid over top sieve is closed and agitated
by hand pouring it over a set of sieves and shaking. Material collected on each sieve
size, percent retained on each sieve and the percent passing each sieve is determined for
the samples that retrieved from the Kisan Quarry in Uşak for 15 days.
Washed sieve analysis is conducted to obtain the washed gradation for the samples
passing through No.4 sieve. The material is washed over a No. 200 sieve to remove the
dust then dried, weighed, poured over a nest of sieves (Table 6 .), shaken by hand, and
the percent retained on each sieve and the percent passing each sieve is determined.
Table 6.5 Sieve types that are used in sieve analysis
Sieve Sizes mm inch 25.4 19.1 12.7 9.52 4.76 2.00 0.42 0.177 0.075
1" 3/4" ½"
3/8" No.4 No.10 No.40 No.80 No.200
The types of the aggregates used in mix designs were basalt and limestone. The sieve
analysis results of specimens that taken from quarries for fifteen days are presented in
Table 6.6
62
Table 6.6 The fifteen days sieve analysis taken from quarries
inch mm 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ORT.1" 25.4 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0
3/4" 19.1 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.01/2" 12.7 66.7 66.2 69.3 69.6 68.2 67.9 70.3 65.7 69.3 67.1 68.8 64.4 66.2 62.0 62.1 66.93/8" 9.52 33.8 28.5 30.4 31.3 33.2 34.0 34.2 31.9 33.5 31.7 32.9 28.3 33.3 31.0 31.0 31.9No.4 4.76 0.8 0.5 0.6 0.3 0.6 0.7 0.8 0.5 0.4 0.4 0.5 0.5 0.8 1.3 0.6 0.6No.10 2.00No.40 0.42No.80 0.177
No.200 0.075
inch mm 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ORT.1" 25.4
3/4" 19.11/2" 12.73/8" 9.52 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0No.4 4.76 30.9 19.5 26.7 19.3 18.2 19.2 18.2 17.8 19.3 19.2 20.1 23.1 19.8 18.4 19.2 20.6No.10 2.00 1.6 0.3 1.0 0.8 0.6 0.4 0.5 0.3 0.4 0.4 0.3 0.6 1.0 0.6 0.7 0.6No.40 0.42No.80 0.177
No.200 0.075
inch mm 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ORT.1" 25.4
3/4" 19.11/2" 12.73/8" 9.52No.4 4.76 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100 100.0 100.0 100.0 100.0 100.0 100.0 100.0No.10 2.00 62.2 69.7 68.9 65.5 62.3 62.3 60.3 62.2 61.5 62.3 62.2 61.4 62.2 62.6 62.3 63.2No.40 0.42 18.8 26.2 24.9 21.3 21.4 21.4 22.1 19.3 20.4 18.2 19.9 20.3 20.4 19.9 20.8 21.0No.80 0.177 11.3 13.7 13.1 10.7 12.3 9.8 11.9 9.1 10.2 9.9 10.1 10.5 10.7 10.3 10.3 10.9
No.200 0.075 7.0 8.9 8.3 6.3 7.8 5.8 7.6 5.9 6.3 6.1 6.7 6.5 6.4 6.0 5.9 6.8
inch mm 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ORT.1" 25.4
3/4" 19.11/2" 12.73/8" 9.52No.4 4.76 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100 100.0 100.0 100.0 100.0 100.0 100.0 100.0No.10 2.00 69.5 68.0 63.0 62.8 64.3 65.1 68.8 67.3 66.1 63.2 64.1 63.2 63.2 63.1 65.0 65.1No.40 0.42 36.9 34.9 32.0 32.5 33.3 34.2 35.0 34.9 35.2 32.7 33.6 32.9 33.9 34.2 35.3 34.1No.80 0.177 29.4 28.3 26.6 26.8 27.1 28.4 29.1 28.8 27.9 26.7 26.9 26.6 27.0 26.9 27.8 27.6
No.200 0.075 22.2 21.6 20.5 20.2 20.9 21.3 21.6 21.1 21.3 20.8 21.3 20.9 21.1 20.8 21.0 21.1
SIEVESIZE
NO:4 -- 0 ŞAPHANE BASALT QUARRY
NO:4 -- 0 SİVASLI LIMESTONE QUARRY
3/4 -- 3/8 ŞAPHANE BASALT QUARRY
3/8 --NO 4 ŞAPHANE BASALT QUARRY
SIEVESIZE
SIEVESIZE
SIEVESIZE
PERCENT PASSING
PERCENT PASSING
PERCENT PASSING
PERCENT PASSING
63
6.1.5 Bulk Specific Gravity and Water Absorption Of Coarse Aggregate
4000 g of aggregates retained on No.4 sieve are washed and dried in the oven at
105°C till the samples maintain a constant weight. The dried samples are cooled till a
handling temperature and immersed in water at room temperature for 24 hours.
Figure 6.2 The samples immersed in water and the balance
The samples are removed from water, surface-dried by the help of a tower, weighed
and recorded as B. The saturated surface-dry sample is placed in a wire basket,
immersed in water, the container which filled with water is shaken to release any
entrapped air, the sample are weighed underwater and recorded as C.
The sample is then removed from the water, drained and placed in an oven and dried
in oven at 105 °C to a constant weight. The oven-dried samples are cooled for 1 hour at
room temperature, weighed and recorded as A.
The specific gravity and absorption are calculated as follows:
Apparent specific gravity, Gsa = A/(A-C)
Bulk specific gravity, Gsh = A / (B-C)
64
Absorbtion, % = (B-A) x 100 / A where,
A= oven - dried weight of aggregate, g;
B= Saturated Surface-Dry (SSD) Weight Of Aggregate, g; and
C= submerged weight of aggregate in water, g.
The test results of specific gravity and water absorbtion of coarse aggregate are given
in tables below.
Table 6.7 Specific weight of coarse aggregate and water absorption of 1.mixture design
A Oven - Dried Weight of Aggregate 2470.0
B Saturated Surface-Dry (SSD) Weight Of Aggregate 2538.0
C Submerged Weight of Aggregate in Water 1556.0
A / (B-C) Bulk Specific Gravity 2.515
A / (A-C) Apparent Specific Gravity 2.702
(B-A) x 100 / A Absorption, % 2.75
Table 6.8 Specific weight of coarse aggregate and water absorption of 2.mixture design
A Oven - Dried Weight of Aggregate 2428.0
B Saturated Surface-Dry (SSD) Weight Of Aggregate 2498.0
C Submerged Weight of Aggregate in Water 1538.0
A / (B-C) Bulk Specific Gravity 2.529
A / (A-C) Apparent Specific Gravity 2.728
(B-A) x 100 / A Absorption, % 2.883
65
Table 6.9 Specific weight of coarse aggregate and water absorption of 3.mixture design
A Oven - Dried Weight of Aggregate 2428.0
B Saturated Surface-Dry (SSD) Weight Of Aggregate 2498.0
C Submerged Weight of Aggregate in Water 1538.0
A / (B-C) Bulk Specific Gravity 2.529
A / (A-C) Apparent Specific Gravity 2.728
(B-A) x 100 / A Absorption, % 2.883
Table 6.10 Specific weight of coarse aggregate and water absorption of 4.mixture design
A Oven - Dried Weight of Aggregate 2568.0
B Saturated Surface-Dry (SSD) Weight Of Aggregate 2653.0
C Submerged Weight of Aggregate in Water 1621.0
A / (B-C) Bulk Specific Gravity 2.488
A / (A-C) Apparent Specific Gravity 2.712
(B-A) x 100 / A Absorption, % 3.310
6.1.6 Specific Gravity and Water Absorption of Fine Aggregate.
Equipment and procedures for determining the specific gravity and absorption of fine
aggregates are described in AASHTO T84 and ASTM C128.
The samples were dried in an oven at 105 °C until constant weight. The pycnometer
is calibrated by filling with water at 25°C to the calibration line and the weight recorded
66
as B. The samples were washed through No. 200 mesh until the washing water became
clear. The washed samples were placed in a pan; then water was added until it covered
the surface of the aggregates completely for 24 hours. Afterwards, the samples were
carefully drained in a manner to avoid loss of any fine particles. The fine aggregate is
spread on a clean flat surface and exposed to a gently moving current of warm air until a
saturated surface dry condition is achieved. Cone – shaped mold is filled with drying
aggregate and the sample is lightly tamped into the mold with 25 light drops of a small
metal tamper. A saturated surface-dry condition is reached at the moisture content at
which the lightly compacted material in a cone first slumps when the cone is removed.
The aggregate has some cohesion as long as there is surface moisture but has no
cohesion when the surface moisture evaporates; hence, the fine aggregate slumps when
the cone is removed.
Figure 6.3 Filling the cone - shaped mold and saturated surface – dry specimen
Once, the particles were saturated-surface dry, about 500 g saturated surface dry
sample was placed in a pycnometer and the weight of the sample recorded as D. Water
was added to the pycnometer till the surface of the sample was fully covered. Then,
pycnometer was snaked until whole air bubbles were disappeared. The pycnometer was
placed into the water bath at temperature of 25 °C for 30 minutes and weight is recorded
as C.
67
Figure 6.4 Filling the pycnometer and specimens in water bath.
The fine aggregate is removed from the pycnometer, oven - dried to a constant weight
at 105 °C, and the weight recorded as A and the calculations are as follows;
Apparent specific gravity, Gsa = A / (B + A - C)
Bulk specific gravity, Gsb = A / (B + D - C)
Absorption, % = (D – A) / A x 100
where,
A = weight of oven-dry sample, g;
B = weight of flask (pycnometer) filled with water, g;
C = weight of flask (pycnometer) with specimen and water to calibration mark, g; and
D = saturated surface dry weight (500 ± 10 grams).
The test results of specific gravity and water absorbtion of fine aggregates are given
in Table 6. 11– Table 6.14
68
Table 6.11 Specific weight of fine aggregate and water absorption of 1.Mixture design
A Weight of the Pycnometer(g) 204.6 206.5
B Weight of the Pycnometer + Water (g) 1196.8 1199.8
C Weight of the Pycnometer + Saturated Surface Dry Weight (g) 704.6 706.5
D Weight of the Pycnometer + Sample + Water (g) 1503.0 1507.1
E Dry Weight of the Sample (g) 486.3 486.5 Average
E / (B+C-A-D) Bulk Spesific Gravity 2.509 2.525 2.517
E / (B + E - D) Apparent Specific Gravity 2.700 2.715 2.708
( C - A - E) x 100 / E Absorption, % 2.82 2.77 2.796
Table 6.12 Specific weight of fine aggregate and water absorption of 2.mixture design
A Weight of the Pycnometer(g) 204.6 206.5
B Weight of the Pycnometer + Water (g) 1196.8 1199.8
C Weight of the Pycnometer + Saturated Surface Dry Weight (g) 704.6 706.5
D Weight of the Pycnometer + Sample + Water (g) 1507.4 1510.8
E Dry Weight of the Sample (g) 489.5 489.8 Average
E / (B+C-A-D) Bulk Spesific Gravity 2.584 2.592 2.588
E / (B + E - D) Apparent Specific Gravity 2.736 2.739 2.738
( C - A - E) x 100 / E Absorption, % 2.15 2.08 2.114
69
Table 6.13 Specific weight of fine aggregate and water absorption of 3.mixture design
A Weight of the Pycnometer(g) 204.6 206.5
B Weight of the Pycnometer + Water (g) 1196.8 1199.8
C Weight of the Pycnometer + Saturated Surface Dry Weight (g) 704.6 706.5
D Weight of the Pycnometer + Sample + Water (g) 1507.4 1510.8
E Dry Weight of the Sample (g) 489.5 489.8 Average
E / (B+C-A-D) Bulk Specific Gravity 2.584 2.592 2.588
E / (B + E - D) Apparent Specific Gravity 2.736 2.739 2.738
( C - A - E) x 100 / E Absorption, % 2.15 2.08 2.114
Table 6.14 Specific weight of fine aggregate and water absorption of 4.mixture design
A Weight of the Pycnometer(g) 204.6 206.5
B Weight of the Pycnometer + Water (g) 1196.8 1199.8
C Weight of the Pycnometer + Saturated Surface Dry Weight (g) 704.6 706.5
D Weight of the Pycnometer + Sample + Water (g) 1508.7 1511.0
E Dry Weight of the Sample (g) 491.7 491.2 Average
E / (B+C-A-D) Bulk Specific Gravity 2.614 2.602 2.608
E / (B + E - D) Apparent Specific Gravity 2.735 2.729 2.732
( C - A - E) x 100 / E Absorption, % 1.69 1.79 1.740
70
The test results of specific gravity of filler are given in Table 6.15 – Table 6.18.
Table 6.15 Specific weight of filler of 1.Mixture design
A Weight of the Pycnometer(g) 156.100 155.500
B Weight of the Pycnometer + Water (g) 653.200 652.800
C Weight of the Pycnometer + Dry Weight of The Sample (g) 258.100 256.800
D Weight of the Pycnometer + Sample + Water (g) 717.800 716.500
Average
(C-A) / ((B-A) - (D-C)) Apparent Specific Gravity 2.727 2.694 2.711
Table 6.16 Specific weight of filler of 2.mixture design
A Weight of the Pycnometer(g) 156.100 155.500
B Weight of the Pycnometer + Water (g) 653.200 652.800
C Weight of the Pycnometer + Dry Weight of The Sample (g) 265.700 265.800
D Weight of the Pycnometer + Sample + Water (g) 722.400 722.400
Average
(C-A) / ((B-A) - (D-C)) Apparent Specific Gravity 2.713 2.710 2.712
Table 6.17 Specific weight of filler of 3.mixture design
A Weight of the Pycnometer(g) 156.100 155.500
B Weight of the Pycnometer + Water (g) 653.200 652.800
C Weight of the Pycnometer + Dry Weight of The Sample (g) 265.700 265.800
D Weight of the Pycnometer + Sample + Water (g) 722.400 722.400
Average
(C-A) / ((B-A) - (D-C)) Apparent Specific Gravity 2.713 2.710 2.712
71
Table 6.18 Specific weight of filler of 4.mixture design
A Weight of the Pycnometer(g) 156.100 155.500
B Weight of the Pycnometer + Water (g) 653.200 652.800
C Weight of the Pycnometer + Dry Weight of The Sample (g) 276.200 275.400
D Weight of the Pycnometer + Sample + Water (g) 729.000 728.400
Average
(C-A) / ((B-A) - (D-C)) Apparent Specific Gravity 2.711 2.707 2.709
6.1.7 Bulk Specific Gravity of Bitumen
The pycnometer of 25 ml. is weighted and recorded as A. Then it is filled with
distilled water and heated in the water bath to a temperature of 25 C for 40 min. It is
then taken out and the weight is determined as B. The pycnometer is filled
(approximately half of it) with the bitumen and after it has been slightly heated, its
weight recorded as C. Water is added to the pycnometer filled with bitumen and heated
in the water bath to a temperature of 25 C then the weight is determined as D. The
calculations are as follows;
Specific Weight of the Bitumen (Gb)= (C-A)/(B-A)-(D-C)
The test results of specific gravity of filler are given in Table 6.19 – Table 6.22.
72
Table 6.19 Specific weight of bitumen of 1.Mixture design
A Weight of the Pycnometer(g) 156,100 155,500
B Weight of the Pycnometer + Water (g) 714,800 713,200
C Weight of the Pycnometer Filled With Asphalt (g) 258,100 256,800
D Weight of the Pycnometer
Filled With Asphalt + Water (g)
717,800 716,600 Average
(C-A) / ((B-A) - (D-C)) Specific Weight of the Bit. 1,030 1,034 1,032
Table 6.20 Specific weight of bitumen of 2.mixture design
A Weight of the Pycnometer(g) 156,100 155,500
B Weight of the Pycnometer + Water (g) 715,420 713,900
C Weight of the Pycnometer Filled With Asphalt (g) 258,100 256,800
D Weight of the Pycnometer Filled With Asphalt + Water (g) 717,800 716,200 Average
(C-A) / ((B-A) - (D-C)) Specific Weight of the Bit. 1,024 1,026 1,025
Table 6.21 Specific weight of bitumen of 3.mixture design
A Weight of the Pycnometer(g) 156,100 155,500
B Weight of the Pycnometer + Water (g) 704,200 704,200
C Weight of the Pycnometer Filled With Asphalt (g) 258,100 256,800
D Weight of the Pycnometer Filled With Asphalt + Water (g) 707,300 707,400
Average
(C-A) / ((B-A) - (D-C)) Specific Weight of the Bit. 1,031 1,033 1,032
73
Table 6.22 Specific weight of bitumen of 4.mixture design
A Weight of the Pycnometer(g) 156,100 155,500
B Weight of the Pycnometer + Water (g) 704,200 704,200
C Weight of the Pycnometer Filled With Asphalt (g) 258,100 256,800
D Weight of the Pycnometer Filled With Asphalt + Water (g) 707,300 707,400
Average
(C-A) / ((B-A) - (D-C)) Specific Weight of the Bit. 1,031 1,033 1,032
6.1.8 Penetration Of Bituminous Materials
The sample is heated till it is sufficiently fluid to pour. It is poured into the sample
container and cooled at room temperature for 1.5 hours. The container is placed in the
water bath at 25 C in a transfer dish. The container is covered with water from the bath
and the transfer dish is placed on the stand of the penetrometer. The penetrometer dial
adjusted to zero, the needle which has 100 g total weight is released and after 5 sec. the
penetration is read in tenths of millimeter. The test is repeated for 3 times and average of
test result accepted as penetration of the bitumen.
Table 6.23 Penetration Grade of Bitumen
Bitumen Type AC 50 - 70 0.1
Bitumen Source ALİAĞA
Penetration Readings mm
Test Conditions First 65
Weight 100 g Second 63
Temperature 25 ± 0.1 ºC Third 64
Duration 5 Seconds Average 64
74
Table 6.24 Penetration Grade of Bitumen
Bitumen Type AC 50 - 70 0.1
Bitumen Source ALİAĞA
Penetration Readings mm
Test Conditions First 64
Weight 100 g Second 65
Temperature 25 ± 0.1 ºC Third 64
Duration 5 Seconds Average 64
6.2 Marshall Mix Design Method
6.2.1 Preparing Specimens
Approximately 23 kg of coarse and fine aggregate, 8 kg mineral filler and 4 liters of
asphalt are prepared for each design. The aggregates are dried to a constant weight at
105 C, sieved into 19.0 to 9.5 mm (3/4 to 3/8 in.). 9.5 to 4.75 mm (3/8 in. to No. 4), 4.75
to 2.36 mm (No. 4 to No. 8), and passing 2.36 mm (No. 8) by dry – sieving and stored in
sealable containers.
Determination of Mixing and Compaction Temperature - the temperature to which
the asphalt must be heated to produce viscosities of 170 ± 20 centistokes kinematic and
280 ± 30 centistokes kinematic shall be established as the mixing temperature and
compaction temperature, respectively.
The specimen mold is cleaned and heated in the oven at 150 °C. The compactor
hammer is cleaned and heated on the hot plate.
The test specimens are weighed, separated into different pans and placed in oven to
be heated at 155 °C. A sufficient amount of asphalt cement is heated to mixing
75
temperature. 20 specimens are prepared which consists of three specimens for each
combination of aggregates and asphalt content.
Heated aggregates removed from oven and charged into mixing bowl which is placed
on scale. A crater in the dry blended aggregate is formed, required amount of asphalt
cement added into the mixture and mixed by the help of a mechanical mixer for 50
seconds.
Figure 6.5 Mixing aggregate and bitumen with the mechanical mixer
Temperature of the sample is checked to control weather it is at mixing temperature
or not, a piece of waxed paper disc is placed into the bottom of preheated Marshall mold
and the sample is poured in mold. The mixture is spaded with a heated spatula 15 times
around the perimeter and 10 times over the interior.
The collar and mound materials inside the mold is removed, the mold and base plate
is attached to the pedestal, the preheated hammer placed into the mold, 75 number of
76
blows applied to the top side of the specimen. The mold is removed from the base plate,
a paper disc is placed on top of the specimen, the mold is rotated 180° so that the top
surface is on bottom and same number of blows applied to the face of the reversed
specimen. After compaction, the base plate is removed and the specimen left to cool in
air until no deformation will result when removing it from the mold.
6.2.2 Bulk Specific Gravity of Marshall Samples
Compacted specimens are removed from molds, weighed at room temperature, and
the dry mass is recorded as A. Samples are submerged in the water-filled container at
25°C and the submerged mass is recorded as C. The samples are removed from water,
dried with a damp towel, weight of the saturated surface-dry sample is recorded as B and
the calculations are as follows;
Bulk specific gravity = Gmb = A / (B-C)
A = mass of sample in air (g)
B = mass of SSD sample in air (g)
C = mass of sample in water (g)
6.2.3 Marshall Stability and Flow Test
A 101.6 mm (4.00 in.) diameter metal cylinder is placed in the testing head and the
flow meter value adjusted to zero. The specimens are immersed in water bath at 60° C
for 30 minutes before test. The surfaces of testing head are cleaned and the guide rods
are lubricated with a thin film of oil. The test specimens are removed from water, patted
with towel to remove excess water and placed in the Marshall testing head. The load is
applied to specimen at constant rate of deformation 51 mm per minute till the maximum
load is reached. When load just begins to decrease (failure starts) the flow meter is
77
removed, ram movement is stopped, and the stability (maximum load) in lbs (Newtons)
and flow in 0.01 inches (0.25 mm) is recorded.
6.2.4 Theoretical Maximum Specific Gravity
Figure 6.6 Separated particles and vacuum mechanism
The pycnometer is calibrated by filling it with water at 25°C and the mass of the
pycnometer plus water is recorded as D. The particles of the sample are separated by
hand, taking care to avoid fracturing the aggregate, so that the particles of the fine
aggregate portion are not larger than 6.3 mm (1/4 in.). The sample is oven dried to a
constant mass at temperature of 105°C and left to cool in room temperature.
Figure 6.7 The entrapped air and agitating the sample
78
The sample is placed in the pycnometer and the determined mass is recorded as A.
Sufficient water at 25°C is added into pycnometer. The entrapped air in the sample is
removed by applying vacuum for 20 minutes. During vacuum period the container is
agitated by hand at intervals of 2 or 3 minutes. At the end of the vacuum period the
vacuum released slowly, the pycnometer is filled with water at 25°C and determined
total mass of the pycnometer plus contents are recorded as E. The maximum theoretical
specific gravity of the bituminous mixture is calculated at 25°, as follows:
Theoretical maximum specific gravity = Gmm = A / (A+D-E)
Where:
A = sample mass in air (g)
D = mass of flask filled with water (g)
E = mass of flask and sample filled with water (g)
6.2.5 Results of Four Different Marshall Mix Design
6.2.5.1 Marshall Mix Design with Basalt Fractions (3/4”-3/8, 3/8-No.4, No.4-0)
and Mineral Filler(No.40 – 0) (First Design)
79
Table 6.25 Combined gradation and specification limits of 1.mixture design
BASALT-1 BASALT-2 BASALT-3 FILLER COMBINED3/4-3/8 3/8-No.4 No.4-0 No.40-0 GRADATION34% 24% 36% 6% 100%
mm inch Passing % Passing % Passing % Passing % Passing % min max min max37.5 1 1/2" 100 100 100 100 100 100 100 100.0 100.025.4 1" 100.0 100.0 100.0 100.0 100.0 100 100 100.0 100.019.1 3/4" 100.0 100.0 100.0 100.0 100.0 100 100 100.0 100.012.7 1/2" 63.6 100.0 100.0 100.0 87.6 83 100 83.0 92.69.52 3/8" 31.9 100.0 100.0 100.0 76.8 70 90 71.8 81.84.76 No.4 0.8 20.6 100.0 100.0 47.2 40 55 42.2 52.22.00 No.10 0.0 0.6 63.2 100.0 28.9 25 38 25.0 32.90.42 No.40 0.0 0.0 21.0 98.9 13.5 10 20 10.0 17.50.177 No.80 0.0 0.0 10.9 95.6 9.7 6 15 6.0 13.70.075 No.200 0.0 0.0 6.8 77.4 7.1 4 10 5.1 9.1
SPESIFICA-TION LIMITS
TOLERANCE LIMITS
SIEVESIZE
Table 6.26 Effective Specific Weight of the Aggregate Mixture of 1.Mixture design
A Weight of the Pycnometer(g) 1323.0 1172.0
B Weight of the Pycnometer + Water (g) 3299.0 3192.0
C Weight of the Pycnometer + Uncompacted Bituminous
Mixture (g) 2516.0 2365.0
D Weight of the Pycnometer +
Water + Uncompacted Bituminous Mixture (g)
3997.0 3887.0
(C-A) / ((C-A) - (D-B))
Max. Theorical Spesific Weight 2.410 2.396
Average
Wa Bitumen Content 5.00 5.50
Gbit Spesific Weight of Bitumen 1.032 1.032
Geff = 100 / ((100+Wa) / Dt
- (Wa/Gb)) Effective Specific Weight 2.583 2.583 2.583
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519.
32.
301
2.30
1194
0.92
811
092.
281
2.39
54.
7714
.48
67.1
2.33
1136
136.
0068
.115
565
.765
.866
.165
.911
95.0
677.
211
97.0
519.
82.
299
2.50
1206
0.94
611
4114
6.00
68.1
155
66.0
65.4
65.5
65.6
1188
.067
4.1
1191
.051
6.9
2.29
82.
4012
030.
951
1144
156.
0068
.115
565
.265
.765
.865
.611
93.0
676.
411
96.0
519.
62.
296
2.50
1242
0.95
211
832.
298
2.38
03.
4814
.26
75.6
2.47
1156
166.
5073
.815
566
.165
.865
.665
.811
91.0
676.
411
92.0
515.
62.
310
2.50
1212
0.94
711
4717
6.50
73.8
155
67.4
67.0
66.8
67.1
1192
.067
2.7
1193
.052
0.3
2.29
12.
8013
250.
920
1220
186.
5073
.815
567
.467
.067
.067
.111
90.0
670.
911
91.0
520.
12.
288
2.90
1289
0.91
911
852.
296
2.36
62.
9414
.72
80.0
2.73
1184
5.75
Opt
imum
Bitu
men
Con
tent
( Fr
om G
raph
s)2.
294
2.38
84.
0014
.463
.02.
45Fi
ll/B
itSt
b/Fl
ow11
48W
eari
ng C
oars
e Sp
esifi
catio
ns(3
-5)
min
14(6
5-75
)(2
-4)
max
1.5
min
900
Pb=1
00×G
b×(G
ef-G
sb)/(
Gef
×Gsb
)
Vh=
(Dt-D
p)×1
00/D
t
1½"
100.
0
VM
A=1
00-(
Dp×
(100
-Wa/
(1+W
a/10
0))/G
sb)
Vf=
(VM
A-V
h)×1
00/V
MA
Gsb
=100
/(%K
/Gk-
h+%İ/G
i-h+%
F/G
f-z)
App
eren
t Spe
sifi
c G
ravi
ty o
f Fill
er,G
f-z
Gsa
=100
/(%K
/Gk-
z+%İ/G
i-z+%
F/G
f-z)
Bul
k Sp
esif
ic G
ravi
ty o
f Bitu
men
,Gb
App
eren
t Spe
sifi
c G
ravi
ty o
f Coa
rse
Agg
,Gk-
z
No
The
hei
ght o
f the
Bri
quet
te
V=B
-C
Dp=
A/V
Dt=
(100
+Wa)
/(100
/Gef
f+W
a/G
b)
App
eren
t Spe
sifi
c G
ravi
ty o
f Fin
e A
gg,G
i-z
Bul
k Sp
esifi
c G
ravi
ty o
f Coa
rse
Agg
,Gk-
hPe
netr
atio
n of
Bitu
men
Bitu
men
Abs
orbt
ion
of A
ggre
gate
P ba
App
eren
t Spe
sifi
c G
ravi
ty o
f Aggı,G
sa
Bul
k Sp
esifi
c G
ravi
ty o
f Fin
e A
gg,G
i-h
Effe
ctiv
e Sp
ecifi
c W
eigh
t of M
ix,G
ef
Bul
k Sp
esif
ic G
ravi
ty o
f Agg
,Gsb
Figu
re 6
.9 G
raph
s plo
tted
to fi
nd o
ut o
ptim
um b
itum
en o
f 1. m
ixtu
re d
esig
n
Stab
ilty,
kg
900
1000
1100
1200
1300
3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
Flow
,mm
1.00
1.50
2.00
2.50
3.00
3.50
4.00
3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
VFA
,%
30.0
40.0
50.0
60.0
70.0
80.0
90.0 3.
003.
504.
004.
505.
005.
506.
006.
507.
00
Void
s,%
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.0
0 3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
V.M
.A,%
10.0
0
11.0
0
12.0
0
13.0
0
14.0
0
15.0
0
16.0
0
17.0
0
18.0
0
19.0
0
20.0
0 3.00
4.00
5.00
6.00
7.00
Prac
tical
Spe
sific
Gra
vity
2.23
0
2.24
0
2.25
0
2.26
0
2.27
0
2.28
0
2.29
0
2.30
0
2.31
0 3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
82
83
6.2.5.2 Marshall Mix Design with Basalt Fractions (3/4”-3/8, 3/8-No.4, No.4-0) and
Limestone (No.4 – 0) (Second Design)
Table 6.28 Combined gradation and specification limits of 2.mixture design
BASALT-1 BASALT-2 BASALT-3 LIMESTONE COMBINED3/4-3/8 3/8-No.4 No.4-0 No.4-0 GRADATION27% 32% 8% 33% 100%
mm inch Passing % Passing % Passing % Passing % Passing % min max min max37.5 1 1/2" 100 100 100 100 100 100 100 100.0 100.025.4 1" 100.0 100.0 100.0 100.0 100.0 100 100 100.0 100.019.1 3/4" 100.0 100.0 100.0 100.0 100.0 100 100 100.0 100.012.7 1/2" 63.6 100.0 100.0 100.0 90.2 83 100 85.2 95.29.52 3/8" 31.9 100.0 100.0 100.0 81.6 70 90 76.6 86.64.76 No.4 0.8 17.7 100.0 100.0 46.9 40 55 41.9 51.92.00 No.10 0.0 0.9 61.4 65.8 26.9 25 38 25.0 30.90.42 No.40 0.0 0.0 19.8 34.2 12.9 10 20 10.0 16.90.177 No.80 0.0 0.0 10.0 27.7 9.9 6 15 6.0 13.90.075 No.200 0.0 0.0 6.3 20.7 7.3 4 10 5.3 9.3
SIEVESIZE SPESIFICA-
TION LIMITSTOLERANCE
LIMITS
Table 6.29 Effective Specific Weight of the Aggregate Mixture of 2.mixture design
A Weight of the Pycnometer(g) 1323.0 1172.0
B Weight of the Pycnometer + Water (g) 3299.0 3192.0
C Weight of the Pycnometer + Uncompacted Bituminous
Mixture (g) 2515.0 2363.0
D Weight of the Pycnometer +
Water + Uncompacted Bituminous Mixture (g)
3999.0 3892.0
(C-A) / ((C-A) - (D-B)) Max. Theorical Specific Weight 2.423 2.426
Average
Wa Bitumen Content 5.00 5.50
Gbit Specific Weight of Bitumen 1.032 1.032
Geff = 100 / ((100+Wa)/ Dt -
(Wa/Gb)) Effective Specific Weight 2.598 2.620 2.609
Figu
re 6
.10
Agg
rega
te g
rada
tion
char
t of
2. m
ixtu
re d
esig
n on
loga
rithm
ic sc
ale
0102030405060708090100
200
100
8060
5040
3020
1610
84
1/4"
3/8"
1/2"
3/4"
1"11/
4"13/
4"11/
2'"
2"31/
2"21/
2'"
3"
Mix
Gra
d.
Spes
f.Lim
itsTo
ler.
Lim
its
84
85
Tabl
e 6.
30 S
umm
ariz
ed re
port
of M
arsh
all M
ix D
esig
n fo
r 2. m
ixtu
re d
esig
n :
642,
515
Gef
-exp
:2,
618
:1,
025
2,72
0G
ef-c
alc.
:2,
654
:0,
582,
645
Wei
ght o
f Mar
shal
l Spe
cim
en :
1150
:2,
618
2,73
7N
umbe
r of B
low
s75
:2,
580
2,72
8%
Va=
Vol
ume
of A
gg.in
Mix
.
:84
,58
:2,
727
%V
b=V
olum
e of
Bit.
in M
ix.
:11
,67
%V
h=V
olum
e of
Air
.in
Mix
.
:
3,75
1"3/
4"1/
2"3/
8"N
o.4
No.
10N
o.40
No.
80N
o.20
0C
oars
e A
gg. %
Fine
Agg
%Fi
ller %
100,
010
0,0
90,0
79,6
46,9
26,9
12,9
9,9
7,3
53,0
939
,57
7,34
Wei
ght
Wei
ght
SSD
Vol
ume
Bul
k Sp
c.M
ax.T
eo.
Voi
dV
.M.A
Voi
ds F
illed
Cor
rect
ion
Cor
rect
edB
itum
en C
onte
ntTe
mp.
in A
ir,g
in W
at.,g
wei
ght,g
cm³
Wei
ght
Spc.
Wei
ght
%%
with
Asp
%Fl
owSt
abili
tyFa
ctor
Stab
ility
Wa ,%
g°C
12
3A
vera
geA
CB
VD
pD
tV
hV
.M.A
Vf
mm
kgkg
14,
0046
,014
567
,868
,268
,068
,011
75,2
686,
812
02,1
515,
32,
281
ipta
l2,
6012
800,
898
1150
24,
0046
,014
568
,468
,869
,168
,811
86,2
672,
912
04,3
531,
42,
232
3,20
1320
0,87
711
583
4,00
46,0
145
68,5
68,1
68,4
68,3
1188
,267
2,1
1200
,952
8,8
2,24
73,
7012
750,
890
1134
2,24
02,
470
9,34
16,5
343
,53,
4511
464
4,50
51,8
145
64,4
64,2
64,4
64,3
1183
,866
6,4
1185
,451
9,0
2,28
1ip
tal
3,40
1185
0,97
911
605
4,50
51,8
145
65,2
65,7
65,3
65,4
1186
,267
2,9
1204
,353
1,4
2,23
23,
2013
400,
956
1281
64,
5051
,814
565
,465
,265
,465
,311
88,0
677,
911
90,2
512,
32,
319
2,80
1175
0,95
711
252,
276
2,45
47,
2615
,60
53,4
3,00
1203
75,
0057
,514
565
,365
,565
,665
,511
83,0
675,
011
84,3
509,
32,
323
ipta
l3,
6011
350,
954
1083
85,
0057
,514
564
,964
,264
,364
,511
83,7
674,
411
84,5
510,
12,
321
4,00
1275
0,97
612
459
5,00
57,5
145
65,3
65,5
65,9
65,6
1188
,067
7,9
1190
,251
2,3
2,31
93,
7013
000,
952
1238
2,32
02,
438
4,84
14,3
766
,33,
8512
4110
5,50
63,3
145
64,4
64,9
64,8
64,7
1183
,868
0,4
1185
,450
5,0
2,34
43,
7012
650,
971
1228
115,
5063
,314
564
,964
,664
,464
,611
90,4
685,
411
91,9
506,
52,
350
4,20
1240
0,97
212
0612
5,50
63,3
145
64,9
65,0
64,8
64,9
1185
,468
0,8
1185
,850
5,0
2,34
74,
0012
250,
967
1184
2,34
72,
422
3,08
13,7
677
,63,
9712
0613
6,00
69,0
145
62,7
62,8
63,1
62,9
1184
,268
2,2
1185
,750
3,5
2,35
23,
3011
601,
015
1178
146,
0069
,014
564
,464
,063
,764
,011
83,1
681,
611
83,8
502,
22,
356
4,40
1175
0,98
611
5915
6,00
69,0
145
64,5
64,2
64,5
64,4
1192
,068
5,5
1193
,150
7,6
2,34
83,
7011
950,
978
1168
2,35
22,
406
2,26
13,9
983
,93,
8011
6816
6,50
74,8
145
63,3
63,2
63,6
63,4
1183
,067
8,5
1184
,850
6,3
2,33
73,
6010
101,
002
1012
176,
5074
,814
562
,963
,263
,063
,011
86,4
680,
411
86,5
506,
12,
344
4,00
1130
1,01
111
4218
6,50
74,8
145
64,3
64,8
64,4
64,5
1191
,668
3,9
1192
,350
8,4
2,34
43,
4011
150,
975
1088
2,34
22,
391
2,08
14,7
885
,93,
6710
815,
40O
ptim
um B
itum
en C
onte
nt (
From
Gra
phs)
2,33
42,
425
4,00
14,4
73,0
3,60
Fill/
Bit
Stb/
Flow
1190
Wea
ring
Coa
rse
Spes
ifica
tions
(3-5
)m
in14
(65-
75)
(2-4
)m
ax1.
5m
in90
0
Pb=1
00×G
b×(G
ef-G
sb)/(
Gef
×Gsb
)
Effe
ctiv
e Sp
ecifi
c W
eigh
t of M
ix,G
ef
Bul
k Sp
esifi
c G
ravi
ty o
f Agg
,Gsb
Bul
k Sp
esifi
c G
ravi
ty o
f Fin
e A
gg,G
i-h
Bul
k Sp
esifi
c G
ravi
ty o
f Coa
rse
Agg
,Gk-
hPe
netra
tion
of B
itum
en
Bitu
men
Abs
orbt
ion
of A
ggre
gate
Pba
App
eren
t Spe
sific
Gra
vity
of A
ggı,G
sa
App
eren
t Spe
sific
Gra
vity
of F
ine
Agg
,Gi-z
V=B
-C
No
The
heig
ht o
f the
Briq
uette
Bul
k Sp
esifi
c G
ravi
ty o
f Bitu
men
,Gb
App
eren
t Spe
sific
Gra
vity
of C
oars
e A
gg,G
k-z
Dp=
A/V
Dt=
(100
+Wa)
/(100
/Gef
f+W
a/G
b)G
sa=1
00/(%
K/G
k-z+
%İ/G
i-z+%
F/G
f-z)
1½"
100,
0
VM
A=1
00-(
Dp×
(100
-Wa/
(1+W
a/10
0))/G
sb)
Vf=
(VM
A-V
h)×1
00/V
MA
Vh=
(Dt-D
p)×1
00/D
tG
sb=1
00/(%
K/G
k-h+
%İ/G
i-h+%
F/G
f-z)
App
eren
t Spe
sific
Gra
vity
of F
iller
,Gf-
z
Figu
re 6
.11
Gra
phs p
lotte
d to
find
out
opt
imum
bitu
men
of 2
. mix
ture
des
ign
Stab
ilite
,kg
800
900
1000
1100
1200
1300
1400
3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
Akm
a,m
m
1.00
1.50
2.00
2.50
3.00
3.50
4.00
3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
A.D
.B,%
50.0
60.0
70.0
80.0
90.0
100.
0 3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
Boş
luk,
%
1.00
3.00
5.00
7.00
9.00
11.0
0 3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
V.M
.A,%
10.0
0
11.0
0
12.0
0
13.0
0
14.0
0
15.0
0
16.0
0
17.0
0
18.0
0
19.0
0
20.0
0 3.00
4.00
5.00
6.00
7.00
Dp
2.22
0
2.24
0
2.26
0
2.28
0
2.30
0
2.32
0
2.34
0
2.36
0
2.38
0 3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
86
87
6.2.5.3 Marshall Mix Design with Basalt Fractions (3/4”-3/8, 3/8-No.4, No.4-0) and
Limestone (No.4 – 0) (Third Design)
Table 6.31 Combined gradation and specification limits of 2.mixture design
BASALT-1 BASALT-2 BASALT-3 LIMESTONE COMBINED3/4-3/8 3/8-No.4 No.4-0 No.4-0 GRADATION36% 20% 16% 28% 100%
mm inch Passing % Passing % Passing % Passing % Passing % min max min max37.5 1 1/2" 100 100 100 100 100 100 100 100.0 100.025.4 1" 100.0 100.0 100.0 100.0 100.0 100 100 100.0 100.019.1 3/4" 100.0 100.0 100.0 100.0 100.0 100 100 100.0 100.012.7 1/2" 66.9 100.0 100.0 100.0 88.1 83 100 83.1 93.19.52 3/8" 31.9 100.0 100.0 100.0 75.5 70 90 70.5 80.54.76 No.4 0.6 20.6 100.0 100.0 48.3 40 55 43.3 53.32.00 No.10 0.0 0.6 63.2 65.1 28.5 25 38 25.0 32.50.42 No.40 0.0 0.0 21.0 34.1 12.9 10 20 10.0 16.90.177 No.80 0.0 0.0 10.9 27.6 9.5 6 15 6.0 13.50.075 No.200 0.0 0.0 6.8 21.1 7.0 4 10 5.0 9.0
TOLERANCE LIMITS
SIEVESIZE SPESIFICA-
TION LIMITS
Table 6.32 Effective Specific Weight of the Aggregate Mixture of 3.mixture design
A Weight of the Pycnometer(g) 1323.0 1172.0
B Weight of the Pycnometer + Water (g) 3299.0 3192.0
C Weight of the Pycnometer + Uncompacted Bituminous
Mixture (g) 2515.0 2363.0
D Weight of the Pycnometer +
Water + Uncompacted Bituminous Mixture (g)
3999.0 3892.0
(C-A) / ((C-A) - (D-B))
Max. Theorical Specific Weight 2.423 2.426
Average
Wa Bitumen Content 5.00 5.50
Gbit Specific Weight of Bitumen 1.032 1.032
Geff = 100 / ((100+Wa)/ Dt -
(Wa/Gb)) Effective Specific Weight 2.598 2.620 2.609
Figu
re 6
.12
Agg
rega
te g
rada
tion
char
t of
3.m
ixtu
re d
esig
n on
loga
rithm
ic sc
ale
0102030405060708090100
200
100
8060
5040
3020
1610
84
1/4
"3/
8"1/
2"3/
4"1"
11/4"
13/4"
11/2'
"2"
31/2"
21/2'
"3"
Mix
Gra
d.
Spe
sf.L
imits
Tole
r. Li
mits
88
89
Tabl
e 6.
33 S
umm
ariz
ed re
port
of M
arsh
all M
ix D
esig
n fo
r 3. m
ixtu
re d
esig
n :6
42.
529
Gef
-exp
:2.
609
:1.0
322.
728
Gef
-cal
c.
:
2.64
0:0
.67
2.58
8W
eigh
t of M
arsh
all S
peci
men
:11
35:2
.609
2.73
8N
umbe
r of B
low
s75
:2.5
652.
712
%V
a= V
olum
e of
Agg
.in M
ix.
:
85.0
2:2
.731
%V
b=V
olum
e of
Bit
. in
Mix
. :
10.7
5%
Vh=
Vol
ume
of A
ir .i
n M
ix.
4.24
1"3/
4"1/
2"3/
8"N
o.4
No.
10N
o.40
No.
80N
o.20
0C
oars
e A
gg. %
Fine
Agg
%Fi
ller
%
100.
010
0.0
88.1
75.5
48.3
28.5
12.9
9.5
7.0
51.6
641
.34
7.00
Wei
ght
Wei
ght
SSD
Vol
ume
Bul
k Sp
c.M
ax.T
eo.
Voi
dV
.M.A
Voi
ds F
illed
Cor
rect
ion
Cor
rect
edB
itum
en C
onte
ntTe
mp.
in A
ir,g
in W
at., g
wei
ght,g
cm³
Wei
ght
Spc.
Wei
ght
%%
with
Asp
%Fl
owSt
abili
tyFa
ctor
Stab
ility
Wa,%
g°C
12
3A
vera
geA
CB
VD
pD
tV
hV
.M.A
Vf
mm
kgkg
14.
0045
.415
067
.366
.666
.966
.911
75.3
669.
111
85.6
516.
52.
276
2.10
1778
0.92
316
422
4.00
45.4
150
65.6
65.7
66.1
65.8
1173
.967
0.0
1184
.551
4.5
2.28
22.
2021
050.
947
1994
34.
0045
.415
065
.966
.066
.366
.111
74.0
668.
211
83.8
515.
62.
277
2.00
2443
0.94
223
012.
278
2.46
47.
5514
.61
48.3
2.10
1979
44.
5051
.115
064
.464
.264
.464
.311
78.8
673.
811
82.7
508.
92.
316
2.20
2533
0.97
924
805
4.50
51.1
150
65.2
65.7
65.3
65.4
1182
.067
3.4
1185
.351
1.9
2.30
92.
4022
820.
956
2181
64.
5051
.115
065
.465
.265
.465
.311
78.5
672.
311
83.0
510.
72.
308
2.10
2204
0.95
721
102.
311
2.44
85.
5913
.79
59.4
2.23
2257
75.
0056
.815
065
.365
.565
.665
.511
83.0
675.
011
84.3
509.
32.
323
2.20
2282
0.95
421
788
5.00
56.8
150
64.9
64.2
64.3
64.5
1183
.767
4.4
1184
.551
0.1
2.32
12.
3021
750.
976
2123
95.
0056
.815
065
.365
.565
.965
.611
88.0
677.
911
90.2
512.
32.
319
3.00
2012
0.95
219
162.
321
2.43
24.
5813
.84
66.9
2.50
2072
105.
5062
.415
064
.464
.964
.864
.711
83.8
680.
411
85.4
505.
02.
344
2.80
2127
0.97
120
6511
5.50
62.4
150
64.9
64.6
64.4
64.6
1190
.468
5.4
1191
.950
6.5
2.35
02.
9021
800.
972
2120
125.
5062
.415
064
.965
.064
.864
.911
85.4
680.
811
85.8
505.
02.
347
2.40
2230
0.96
721
562.
347
2.41
62.
8713
.27
78.4
2.70
2114
136.
0068
.115
062
.762
.863
.162
.911
84.2
682.
211
85.7
503.
52.
352
2.70
2266
1.01
523
0014
6.00
68.1
150
64.4
64.0
63.7
64.0
1183
.168
1.6
1183
.850
2.2
2.35
62.
8020
710.
986
2042
156.
0068
.115
064
.564
.264
.564
.411
92.0
685.
511
93.1
507.
62.
348
3.10
1947
0.97
819
042.
352
2.40
12.
0513
.50
84.8
2.87
2082
166.
5073
.815
063
.363
.263
.663
.411
83.0
678.
511
84.8
506.
32.
337
2.70
1783
1.00
217
8717
6.50
73.8
150
62.9
63.2
63.0
63.0
1186
.468
0.4
1186
.550
6.1
2.34
43.
4019
721.
011
1993
186.
5073
.815
064
.364
.864
.464
.511
91.6
683.
911
92.3
508.
42.
344
2.80
1913
0.97
518
662.
342
2.38
61.
8814
.29
86.8
2.97
1882
5.00
Opt
imum
Bitu
men
Con
tent
( Fr
om G
raph
s)2.
329
2.43
24.
0013
.65
72.0
2.49
Fill/
Bit
Stb/
Flow
2150
Wea
ring
Coa
rse
Spes
ifica
tions
(3-5
)m
in14
(65-
75)
(2-4
)m
ax1.
5m
in90
0
Pb=1
00×G
b×(G
ef-G
sb)/
(Gef
×Gsb
)
1½"
100.
0
VM
A=1
00-(
Dp×
(100
-Wa/
(1+W
a/10
0))/
Gsb
)
Vf=
(VM
A-V
h)×1
00/V
MA
Vh=
(Dt-D
p)×1
00/D
tG
sb=1
00/(
%K
/Gk-
h+%İ/G
i-h+%
F/G
f-z)
App
eren
t Spe
sific
Gra
vity
of F
iller
,Gf-
z
Dp=
A/V
Dt=
(100
+Wa)
/(100
/Gef
f+W
a/G
b)G
sa=1
00/(%
K/G
k-z+
%İ/G
i-z+%
F/G
f-z)
Bul
k Sp
esifi
c G
ravi
ty o
f Bitu
men
,Gb
App
eren
t Spe
sific
Gra
vity
of C
oars
e A
gg,G
k-z
No
The
heig
ht o
f the
Bri
quet
te
App
eren
t Spe
sific
Gra
vity
of F
ine
Agg
,Gi-z
V=B
-C
Bul
k Sp
esifi
c G
ravi
ty o
f Coa
rse
Agg
,Gk-
hPe
netr
atio
n of
Bitu
men
Bitu
men
Abs
orbt
ion
of A
ggre
gate
P ba
App
eren
t Spe
sific
Gra
vity
of A
ggı,G
sa
Bul
k Sp
esifi
c G
ravi
ty o
f Fin
e A
gg,G
i-h
Effe
ctiv
e Sp
ecifi
c W
eigh
t of M
ix,G
ef
Bul
k Sp
esifi
c G
ravi
ty o
f Agg
,Gsb
Figu
re 6
.13
Gra
phs p
lotte
d to
find
out
opt
imum
bitu
men
of 3
. mix
ture
des
ign
Stab
ility
,kg
1500
1600
1700
1800
1900
2000
2100
2200
2300
2400
2500
3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
Flow
,mm
1.00
1.50
2.00
2.50
3.00
3.50
4.00
3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
VMA,
%
40.0
50.0
60.0
70.0
80.0
90.0
100.
0 3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
Void
s,%
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.0
0 3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
V.M
.A,%
12.0
0
13.0
0
14.0
0
15.0
0
16.0
0 3.00
4.00
5.00
6.00
7.00
Prac
tical
Spe
cific
Wei
ght
2.27
0
2.28
0
2.29
0
2.30
0
2.31
0
2.32
0
2.33
0
2.34
0
2.35
0
2.36
0 3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
90
91
6.2.5.4 Marshall Mix Design with Basalt Fractions (3/4”-3/8, 3/8-No.4, No.4-0) and
Limestone (No.4 – 0) (Fourth Design)
Table 6.34 Combined gradation and specification limits of 4.mixture design
BASALT-1 BASALT-3 LIMESTONE COMBINED3/4-3/8 No.4-0 No.4-0 GRADATION60% 17% 23% 100%
mm inch Passing % Passing % Passing % Passing % min max min max37.5 1 1/2" 100 100 100 100 100 100 100.0 100.025.4 1" 100.0 100.0 100.0 100.0 100 100 100.0 100.019.1 3/4" 100.0 100.0 100.0 100.0 100 100 80.0 100.012.7 1/2" 66.9 100.0 100.0 80.1 83 100 58.0 80.09.52 3/8" 31.9 100.0 100.0 59.1 70 90 48.0 70.04.76 No.4 0.6 100.0 100.0 40.4 40 55 30.0 52.02.00 No.10 0.0 63.2 65.1 25.7 25 38 20.0 40.00.42 No.40 0.0 21.0 34.1 11.4 10 20 8.0 22.00.177 No.80 0.0 10.9 27.6 8.2 6 15 5.0 14.00.075 No.200 0.0 6.8 21.1 6.0 4 10 2.0 8.0
SIEVESIZE SPESIFICA-
TION LIMITSTOLERANCE
LIMITS
Table 6.35 Effective Specific Weight of the Aggregate Mixture of 4.mixture design
A Weight of the Pycnometer(g) 1323.0 1172.0
B Weight of the Pycnometer + Water (g) 3299.0 3192.0
C Weight of the Pycnometer + Uncompacted Bituminous
Mixture (g) 2504.0 2362.0
D Weight of the Pycnometer +
Water + Uncompacted Bituminous Mixture (g)
3997.0 3891.0
(C-A) / ((C-A) - (D-
B))
Max. Theorical Specific Weight 2.445 2.424
Average
Wa Bitumen Content 4.50 5.00
Gbit Specific Weight of Bitumen 1.032 1.032
Geff = 100 / ((100+Wa)/ Dt
- (Wa/Gb)) Effective Specific Weight 2.606 2.599 2.603
Figu
re 6
.14
Agg
rega
te g
rada
tion
char
t of
4. m
ixtu
re d
esig
n on
loga
rithm
ic sc
ale
0102030405060708090100
200
100
8060
5040
3020
1610
84
1/4
"3/
8"1/
2"3/
4"1"
11/4"
13/4"
11/2'
"2"
31/2"
21/2'
"3"
Mix
Gra
d.
Spe
sf.L
imits
Tole
r. Li
mits
92
93
Tabl
e 6.
36 S
umm
ariz
ed re
port
of M
arsh
all M
ix D
esig
n fo
r 4. m
ixtu
re d
esig
n :6
42.
488
Gef
-exp
:2.
603
:1.0
322.
712
Gef
-cal
c.
:
2.63
0:0
.97
2.60
8W
eigh
t of M
arsh
all S
peci
men
:11
35:2
.603
2.73
2N
umbe
r of B
low
s75
:2.5
412.
709
%V
a= V
olum
e of
Agg
.in M
ix.
:
85.1
3:2
.719
%V
b=V
olum
e of
Bit.
in M
ix.
:9.
88%
Vh=
Vol
ume
of A
ir .i
n M
ix.
:4.
99
1"3/
4"1/
2"3/
8"N
o.4
No.
10N
o.40
No.
80N
o.20
0C
oars
e A
gg. %
Fine
Agg
%Fi
ller %
100.
010
0.0
80.1
59.1
40.4
25.7
11.4
8.2
6.0
59.6
34.4
6.0
Wei
ght
Wei
ght
SSD
Vol
ume
Bul
k Sp
c.M
ax.T
eo.
Voi
dV
.M.A
Voi
ds F
illed
Cor
rect
ion
Cor
rect
edB
itum
en C
onte
ntTe
mp.
in A
ir,g
in W
at.,g
wei
ght,g
cm³
Wei
ght
Spc.
Wei
ght
%%
with
Asp
%Fl
owSt
abili
tyFa
ctor
Stab
ility
Wa,%
g°C
12
3A
vera
geA
CB
VD
pD
tV
hV
.M.A
Vf
mm
kgkg
13.
5039
.715
066
.867
.166
.666
.811
71.7
666.
311
94.9
528.
62.
217
2.20
2524
0.92
623
362
3.50
39.7
150
66.8
68.9
68.9
68.2
1175
.466
9.1
1193
.452
4.3
2.24
22.
4017
670.
893
1578
33.
5039
.715
068
.867
.969
.168
.611
61.8
661.
611
78.0
516.
42.
250
2.30
1915
0.88
216
892.
236
2.47
69.
6714
.96
35.3
2.30
1868
44.
0045
.415
067
.467
.266
.867
.111
70.5
661.
811
78.0
516.
22.
268
2.35
2069
0.91
919
015
4.00
45.4
150
67.9
68.1
67.6
67.9
1181
.467
2.3
1191
.051
8.7
2.27
82.
5017
630.
902
1590
64.
0045
.415
066
.867
.467
.567
.211
76.5
671.
111
85.6
514.
52.
287
2.40
2274
0.91
720
852.
277
2.45
97.
3913
.81
46.5
2.42
1859
74.
5051
.115
066
.466
.565
.966
.311
84.5
677.
611
88.4
510.
82.
319
2.65
1947
0.93
818
268
4.50
51.1
150
66.7
66.9
66.5
66.7
1187
.167
7.9
1190
.251
2.3
2.31
72.
6017
390.
928
1615
94.
5051
.115
066
.166
.065
.565
.911
83.9
676.
111
89.0
512.
92.
308
2.70
2187
0.94
620
692.
315
2.44
35.
2412
.81
59.1
2.65
1836
105.
0056
.815
064
.664
.364
.964
.611
79.9
674.
711
82.5
507.
82.
324
2.80
2043
0.97
319
8811
5.00
56.8
150
65.7
65.4
65.1
65.4
1186
.168
1.7
1189
.150
7.4
2.33
82.
9017
560.
956
1678
125.
0056
.815
065
.065
.665
.265
.311
86.6
678.
011
88.2
510.
22.
326
3.00
1999
0.95
919
162.
329
2.42
74.
0412
.70
68.2
2.90
1861
135.
5062
.415
065
.865
.565
.965
.711
84.7
679.
111
86.5
507.
42.
335
2.80
1836
0.94
917
4214
5.50
62.4
150
64.8
65.2
65.3
65.1
1182
.267
7.8
1183
.950
6.1
2.33
62.
7018
610.
962
1791
155.
5062
.415
064
.664
.865
.164
.811
91.5
685.
011
93.1
508.
12.
345
2.90
2001
0.96
819
372.
339
2.41
23.
0312
.75
76.3
2.80
1823
166.
0068
.115
065
.165
.065
.165
.111
89.4
682.
111
91.2
509.
12.
336
3.00
1750
0.96
316
8517
6.00
68.1
150
65.3
65.5
65.1
65.3
1190
.068
1.8
1192
.051
0.2
2.33
23.
3015
460.
958
1481
186.
0068
.115
065
.064
.464
.864
.711
90.7
682.
011
93.4
511.
42.
328
3.20
1790
0.97
017
372.
332
2.39
72.
6813
.39
80.0
3.17
1634
4.60
Opt
imum
Bitu
men
Con
tent
( Fr
om G
raph
s)2.
318
2.44
05.
0012
.862
.02.
65Fi
ll/Bi
tSt
b/Fl
ow18
55Bi
nder
Coa
rse
Spes
ifica
tions
(4-6
)m
in13
(60-
75)
(2-4
)m
ax1.
4m
in75
0
Pb=1
00×G
b×(G
ef-G
sb)/(
Gef
×Gsb
)
Effe
ctiv
e Sp
ecifi
c W
eigh
t of M
ix,G
ef
Bul
k Sp
esifi
c G
ravi
ty o
f Agg
,Gsb
Bul
k Sp
esifi
c G
ravi
ty o
f Fin
e A
gg,G
i-h
Bul
k Sp
esifi
c G
ravi
ty o
f Coa
rse
Agg
,Gk-
hPe
netra
tion
of B
itum
en
Bitu
men
Abs
orbt
ion
of A
ggre
gate
P ba
App
eren
t Spe
sific
Gra
vity
of A
ggı,G
sa
App
eren
t Spe
sific
Gra
vity
of F
ine
Agg
,Gi-z
V=B
-C
No
The
heig
ht o
f the
Briq
uette
Bul
k Sp
esifi
c G
ravi
ty o
f Bitu
men
,Gb
App
eren
t Spe
sific
Gra
vity
of C
oars
e A
gg,G
k-z
Dp=
A/V
Dt=
(100
+Wa)
/(100
/Gef
f+W
a/G
b)G
sa=1
00/(%
K/G
k-z+
%İ/G
i-z+%
F/G
f-z)
1½"
100.
0
VM
A=1
00-(D
p×(1
00-W
a/(1
+Wa/
100)
)/Gsb
)
Vf=
(VM
A-V
h)×1
00/V
MA
Vh=
(Dt-D
p)×1
00/D
tG
sb=1
00/(%
K/G
k-h+
%İ/G
i-h+%
F/G
f-z)
App
eren
t Spe
sific
Gra
vity
of F
iller
,Gf-z
Figu
re 6
.15
Gra
phs p
lotte
d to
find
out
opt
imum
bitu
men
of 4
. mix
ture
des
ign
Stab
ility
,kg
1500
1600
1700
1800
1900
2000
2100
2200
2300
2400
2500
3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
Flow
,mm
1.00
1.50
2.00
2.50
3.00
3.50
4.00
3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
VFA,
%
40.0
50.0
60.0
70.0
80.0
90.0
100.
0 3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
Void
s,%
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.0
0 3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
V.M
.A,%
10.0
0
11.0
0
12.0
0
13.0
0
14.0
0
15.0
0
16.0
0
17.0
0
18.0
0
19.0
0
20.0
0 3.00
4.00
5.00
6.00
7.00
Prac
tical
Spe
sific
Gra
vity
2.22
0
2.24
0
2.26
0
2.28
0
2.30
0
2.32
0
2.34
0
2.36
0 3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
94
95
6.3 General Description of Pavement Rutting Test
6.3.1 Principles of the L.P.C. Pavement Rutting Test
The purpose of the test performed with the L.C.P.C. Pavement Rutting Tester
(Laboratorie Central des Pont et Chaussees) is to characterize the resistance towards
rutting of the hydrocarbon mixed materials in conditions which are similar o the
promptings on road.
Principles of the test can be summarized as follows: The repeated passage of a tyre
reproducing the load and the pressure of a heavy vehicle includes permanent
deterioration on a specimen of hydrocarbon mixed material. These deteriorations are
called rut for the median pan of the plate and roll for the side parts. The measurement of
these deteriorations, resulting from the accumulation of residual deteriorations according
to the number of passages enables the comparison of different Max combinations.
The equipment for the L.P.C. Pavement Rutting Tester are;
A L.P.C Pavement Rutting Tester fitted with a regulation device of the
temperature (figure 8.1-8.2).
Moulds dimensions: 500* 180* 100 mm, minimum 2 units.
A depth gauge with its support for the measure of the rut depth.
A recorder fitted with sensors allowing the checking of the plates temperature
and possibly the checking of the air inside the rutting tester.
A conformation (optional) which enables the possibility of having an image of the
outlines before and after the test.
96
A pressure gauge for the check of tyres.
The parameters listed below are checked before and during the test.
Tyre displacement 410 mm.
Angle of inclination of the wheel on its swivel: zero
Thickness of the support plate: 19mm.
Dimensions of the specimen; thickness: 100 mm, width: 180 mm, length: 500 mm.
Test Temperature:
The temperature is regulated during the test from a sensor set inside the material hot
air circulating from the top of the device. At 60 C for the surface layers and for the
connection layers. At 50 C for the bottom layer. The specimens are set at room
temperature for 12 hours before the beginning of e test. The maximum difference in
temperature accepted +/- 2 C during the test in relation the test temperature.
Load on each wheel: 5000 N.
The pressure gauge set on the circuit of each hydraulic jack will calibrated in force
applied on to the wheel by the specimen. In order to stop the friction of the jack, a
rubber plate which is 1 cm. thick is set between the instrument and the bottom of the
moving body. The calibration curve is the average curve between ascent and descent.
The weight of the moving body, of the mould and of the specimen has to be taken into
account in order to express the force at the level of contact between the specimen and
the tyre. If the moving body used has not been previously weighed, 48 kg are to be
considered for the first version and 56 kg for the second.
97
Tyre :
Non-grooved tyres Trelleborg 400*8 are to be used. Their pressure has to be
permanently maintained at 0.6 Mpa +/- 0.03 during the test which makes compulsory
either to regulate the pressure or to check it at the beginning of the test once the
specimen has been heated and to check its variation at the end of the test
6.3.2 Test Procedure
The aggregates are divided into fractions; 3/4 inch – 3/8 inch(19 mm – 9.5 mm) of
basalt, 3/8 inch – No.4 (9.5 mm – 4.75 mm) of basalt, minus No.4 (4.75 mm) of basalt
and minus No.4 (4.75 mm) of Limestone in K.G.M. Bituminous Mixture Laboratory.
Afterwards the aggregates placed in oven to dry.
Figure 6.16 Mechanical sieve shaker and view of specimens
The amount of the specimens are calculated according to the gradation that
determined by Marshall Design Method. The aggregates are divided into fractions by the
help of a mechanical sieve shaker, weighed according to design criteria and placed in
oven.
98
Figure 6.17 Preparation of the mixture in the mechanical mixer
After the materials achieved 150ºC temperature, they are removed from the oven,
bitumen added according to the design parameters and mixed in a mechanical mixer.
Because the mechanical mixer capacity was not enough to mix in one batch, the sample
is mixed in 4 batches and put in oven till the temperature of the specimen reaches 145 –
150°C.
The specimens, which are at 150 °C, are removed from oven and placed in a mold
which has dimensions of 100mm x 180mm x 500 mm. Then they are compacted by
using the laboratory tyre compactor. The compaction is done by "L.P.C. Plates
Compactor", as shown in table 8.1.
99
Table 6.37 Strong compaction (Slabs 500x 180xh)
number of passes wheel position tyre pressure jack force start jack operationfront centre rear 1 0.1 MPa 100 daN right locked 1 1 1 1 1 2 0.3MPa 200daN right free 2 1 4 4 2 2 2 1 1 0.3 Mpa 200daN locked 1
1 1 1 1
Figure 6.18 Compaction of the mixture with the L.P.C. Plates Compactor.
100
The compacted specimens are removed from molds and left to cool at room
temperature for 48 hours. The dry mass and the mass under water are determined to
calculate specific gravity and air void content.
Figure 6.19 Determining air content of the sample
After calculation the specimens are placed in the mold and the mold is located in the
LPLC Rutting Pavement Tester.
Rut depths within the tester are defined by deformation expressed as a percentage of
the original slab thickness. Deformation is defined as the average rut depth from a series
measurements which is illustrated in Figure _. _ .
Pi (%) = 100 x ( ∑j (mij - moj) ) / (15 x E)
J: number of measured points
101
mij: the measure of a certain cycle, (average of 15 points)
moj: the measure of after 1.000 cold cycles (average of 15 points)
E: the depth of the sample.
RIG
HT
LEFT
25 mm 25 mm
WHEEL PASSAGE
Figure 6.20 Measuring points of the mold for rutting.
Before carrying out the reports taken as origin for the deterioration measurement, the
specimens are subjected to 1000 cycles without preheating (1 cycle = 1 travel and return
of the tyre).The deterioration measures are than carried out after 100, 300, 1.000, 3.000,
10.000, 30.000 cycles at 60 °C.
102
Figure 6.21 Measurement of deteriorations of the specimen
In order to minimize the dissymmetry effect of the rutting tester and of the
temperature regulation, the specimens corresponding to the same compressing rate are
alternatively set on the left and on the right side of the rutting tester.
The test is stopped when the average rut noticed after a serie of measures is higher
than 10% and that the previous results let anticipate a rut higher than 15% at the
following step.
Figure 6.22 Final view of rutting samples
103
6.4 Results of the Pavement Rutting Tests
RESULTS OF RUTTING TEST
7.68
1.602.092.30
2.75
7.20
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
0 10 000 20 000 30 000 40 000 50 000 60 000
NUMBER OF CYCLES
RU
T D
EPTH
%
2.DESIGN
Figure 6.23 Rutting Test Results of 2. Marshall Mix Design
RESULTS OF RUTTING TEST
1.18
1.86
2.93
3.82
6.36
8.07
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
0 10 000 20 000 30 000 40 000 50 000 60 000
NUMBER OF CYCLES
RU
T D
EPTH
%
3.DESIGN
Figure 6.24 Rutting Test Results of 3. Marshall Mix Design
104
RESULTS OF RUTTING TEST
1.77
2.46
3.59
5.89
6.8
2.79
0
1
2
3
4
5
6
7
8
0 10 000 20 000 30 000 40 000 50 000 60 000
NUMBER OF CYCLES
RU
T D
EPTH
%
4.DESIGN
Figure 6.25 Rutting Test Results of 4. Marshall Mix Design
RESULTS OF RUTTING TEST
1.77
2.46
3.59
5.89
6.8
7.68
1.60
2.092.30
2.75
7.20
8.07
6.36
3.82
2.93
1.86
1.18
2.79
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
0 10 000 20 000 30 000 40 000 50 000 60 000
NUMBER OF CYCLES
RU
T D
EPTH
%
2.DESIGN3.DESIGN4.DESIGN
Figure 6.26 Rutting Test Results of Marshall Mix Designs
105
CHAPTER SEVEN
7 CONCLUSIONS AND SUGGESTIONS
Pavements should have the ability to serve traffic during its design life. The aggregate
which have the appropriate physical properties, gradation and shape results in long and
satisfactory service lives of bituminous mixtures. In bituminous mixtures, type of the
aggregate is directly related to functional and structural failures that will occur in
pavement. Also aggregate properties effects optimum bitumen content of the mixture,
workability, stiffness, stability, durability, permeability, and resistance to moisture
damage in the mixture.
In Turkey permanent deformations like rutting increase because of the increase of
tandem axle loads to 19 tons and single axle load to 13 tons in 1985. Therefore the
problems such as the deformations caused by heavy loaded slow moving vehicles and
being unable to keep the road surface smooth, new techniques should be improved to
cope with these failures.
In this study four different asphalt mix designs are prepared to determine the
optimum combination of aggregate and asphalt binder to achieve the properties of
stability, durability, flexibility, fatigue resistance, skid resistance and rut resistance in the
mixture by forming a strong skeleton. Firstly to obtain desired gradation only the basalt
fractions are used. As the basalt has 17% of Los Angeles abrasion value the percentage
passing No. 4 sieve was not adequate to obtain the desired gradation that complies
specifications. Therefore, the designs are carried out with mineral filler and limestone.
In the first Marshall mix design mineral filler and basalt fractions are used. Although
the design values; stability, flow, air void content, V.M.A.%, V.F.A% and the practical
specific gravity were meeting with minimum specification limits, new designs with
limestone is performed to improve quality.
106
The second Marshall mix design was carried out with basalt fractions (3/4”-3/8, 3/8-
No.4, No.4-0) and Limestone (No.4 – 0). The design values; stability, flow, air void
content, V.M.A.%, V.F.A% and the practical specific gravity was meeting with
specifications, however rutting potential of the mixture showed that decreasing the
limestone content will give more satisfactory results. The ratio of the limestone in the
mixture is decreased and the stability value of more than 1900 kg is obtained.
Theoretically, high amount of coarse aggregate in mixture increases the contacted
surfaces and interlocking of coarse aggregates thus load carrying capacity increases.
Therefore last design was performed with high coarse aggregate content.
During design procedure and construction negative effect of absorption is observed.
The high water absorption value causes high moisture content. It should be mentioned
that in laboratory, aggregates used is completely dry but during plant operations the
dryer of the plant could not dry aggregates sufficiently. After drying process, aggregates
contains between 0.1 – 0.5 percent of moisture by weight. The water absorbed in micro
cracks prevents bitumen penetrate in micro cracks. As a result of this, bitumen content
of the mixture varies according to the moisture content of aggregate. Hence, it was not
possible to control optimum bitumen content and a compatible production with mix
design. Another problem was compaction. Compaction equipment used in laboratory is a
small cylindrical sample and a hammer in stable environmental conditions. Compaction
time is relatively quick. Contradictorily in field conditions there are various types of
rollers, variables in environmental conditions (e.g., ground temperature, air temperature,
wind, foundation support, solar flux) and more than half an hour for compaction. This
brings about insufficient compaction. Hence, actual field conditions show that to achieve
compatible results with laboratory, construction should be strictly controlled.
The results indicate that Basalt aggregates have more angular shape than the
limestone, even though basalt is crushed by a roll-crusher which is not preferred in
crushing processes. This is due to the strength and abrasion resistance of the basalt
which controls roundness. Because the limestone has high Los Angeles abrasion value,
107
it is observed that the limestone was disintegrated under steel wheel rollers during
compaction. The rutting test results show that increase in ratio of limestone results in rut
depth. Another solution like grinding basalt aggregate in crushers to increase the
percentage passing No.4 sieve and usage of basalt instead of limestone or mineral filler
will help to form stronger skeleton. Also the rutting test results show that the high
content of coarse aggregate decreases rutting resistance.
108
REFERENCES
AASTHO. (1993). AASHTO provisional standart TP33, standart test methods for
uncompacted void content of fine aggregate. Washington DC: American Society of
State Highway and Transportation Officials.
AASTHO. (1986). AASHTO Guide For Design Of Pavment Structures. Washington DC:
American Association of State Highway and Transportation Officials.
Asphalt Institute (1996). Superpave Level 1 Mix Design. Lexington KY: Asphalt
Institute Press.
Brown, E.R.(1984), Experiences of Corps of Engineers in compaction of Hot Asphalt
Mixtures Placement and compaction of asphalt mixtures. Texas:FT Wagner.
Chen, W.F. (1995) The Civil Engineering Handbook. Florida: CRC Press.
Collis, L., & Fox, R.A. (1985). Agregates: Sand, gravel and crushed aggregates for
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Cordon, W.A.(1979). Properties, evaluation and control of engineering materials N.Y.:
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Geller, M.(1984), Placement and Compaction of Asphalt Mixtures. Washington:
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Huber, G.A., & Herman G.H.(1987) Effect of asphalt concrete parameters on rutting
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109
Kenedy, P.S., Hubber, G.A., Harrigan, E.T., Cominsky, R.J., Huges, G.S., Qunitus,
H.V., & Moulthrop, J.S. (1994). Superior performing Asphalt pavements (Superpave)
The product of the SHRP Asphalt Research Program SHRP-A-410. Washington DC:
National Research Council.
Littel, A. L., & Fox, B. (2000). Usage of foamed asphalt in base course stabilization:
World Highways Jounal, 87, 32-34.
Middleton W.R. (1987). Asphalt Chemistry (3th ed.). NY: American Chemistry
Society.
Neville, A.M. (1997). Properties of concrete(3th ed.) London: Longman Ltd.
Noland, R. B., & Lem, L. L. (2000). Induced travel: a review of recent literature and the
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Transport Conference 2000.
Read, J., & Whitehoak D. (Eds.). (2003). Shell Bitumen Handbook. London: Thomas
Telford Publishing.
Pike, D.C. (1990). Standards for aggregates Canterbury: Ellis Horwood Publishing.
Roberts, F.L. (1975), State of the art of estimating pavement serviceability using
roughness measurements. American Society of Civil Engineers specialty conference
in pavement design for practicing engineers, Atlanta, U.S.A.
Uluçaylı, M. (2001). Highway Materials Course Notes (Not published) İzmir, DEÜ.
Verstraeten, J. (1994). Bituminous materials with a high resistance to flow rutting.
Belgium: Piarc Technical committee on flexible roads.
110
Wang, J.N., Kenedy, T.W. & McGennis, R.B. (2000). Volumetric and mechanical
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