Sma PMB40
Sma PMB40
Sma PMB40
INTRODUCTION
1.1 General
Stone Matrix Asphalt (SMA) is a type of hot-mix asphalt (HMA) that has been used
in Europe for over 20 years to resist studded-tyre wear and to provide better rutting
resistance. SMA consists of two parts: a coarse aggregate skeleton and a high binder. The
coarse aggregate skeleton provides the mixture with stone-on-stone contact, giving it
strength, while the high binder content mortar adds durability. The mortar is typically
composed of fine aggregate, mineral filler, asphalt binder and a stabilizing additive. This
stabilizing additive acts as to hold the asphalt binder in the mixture during the high
temperatures of production and placement.
Stone Matrix Asphalt (SMA) which basically is a gap graded mixture containing 70-
80% coarse aggregate of total aggregate mass, 6-7% of binder, 8-12% of filler, and about
0.3-0.5% of fibre or modifier. The stabilizing additives composed of cellulose fibres,
mineral fibres, or polymers are added to SMA mixtures to prevent drain down from the
mix.
SMA provides improved performance for high speed, heavily trafficked roads when
compared to more conventional forms of asphalt such as Dense graded asphalt. SMA
provides a smooth, low noise pavement with sufficient texture to promote safety through
reduced water splash and spray and good frictional resistance for vehicle traffic. Its
durability and stability are enhanced by the higher bitumen content and it is able to
support even heavier traffic loads with use of polymer modified binders. At the end of its
service life, like others asphalt, it is 100% recyclable.
SMA has a high proportion of coarse aggregate that interlocks to form a stone-on-
stone skeleton to resist permanent deformation. The stone skeleton is filed with mastic of
bitumen and filler to which fibers are added to provide adequate stability of bitumen and
to prevent drainage of binder during transport and placement. Generally, fibres or
modified binders are used to prevent drainage of the relatively high binder content during
transport and placing.
The rut resistance capacity of SMA stems from a coarse stone skeleton providing
more stone-on-stone contact than with conventional dense graded asphalt. Improved
binder durability is a result of higher bitumen content, a thicker bitumen film and lower
air voids content. This high bitumen content also improves flexibility.
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SMA pavements are proving to be a good alternative to traditional pavements in high
traffic areas. It seems that the benefits outweigh the cost of the mix, and SMA will have a
future in India.
1.2 Desirable properties of Stone Matrix Asphalt
The overall objective of the design of bituminous mixture is to determine an
economical blend of coarse aggregate, fine aggregate, mineral filler and binder.
Sufficient bitumen to ensure a durable pavement.
Sufficient voids in compacted mix to allow slight amount of additional
compaction and traffic loading without flushing and bleeding.
Sufficient workability to permit sufficient placement of the mix without
segregation.
Sufficient flexibility to meet traffic loads, especially in cold season.
Sufficient amount of fibres to control draining of bitumen.
The mix should be an economical for the designed period.
1.3 Advantages of Stone Matrix Asphalt
The following are the advantages of Stone Matrix Asphalt (SMA).
High stability against permanent deformation (rutting) and high wear resistance.
It provides resistance to deformation at high pavement temperatures.
Slow aging and durability to premature cracking of the asphalt.
Longer service-life.
SMA has a higher macro-texture than dense-graded pavements for better friction.
Reduced spray, reduced hydroplaning and reduced noise.
Good low temperature performance.
Even though SMA has a higher cost than conventional dense mixes, approximately 20
to 25 percent, the advantages of longer life (decreased rutting and increased durability),
reduced splash and spray, and reduced surface noise may compensate for the added cost.
The higher cost of SMA is attributed to the addition of mineral filler, fibres, modified
binders, and possible higher asphalt contents.
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1.4 Objectives of the Present Study
To design the Stone Matrix Asphalt (SMA) mix with Lime (1% and 2%), Cement
(1% and 2%) as fillers and Bagasse (0.3%) as a stabilizing additive by Marshall
Method of mix design.
To compare the Marshall Properties of Stone Matrix Asphalt mix with Lime (1%
and 2%), Cement (1% and 2%) as fillers and Bagasse (0.3%) as a stabilizing
additive.
To determine the voids in coarse aggregate by VCA dry rodded test.
To determine the drain down characteristics of Stone Matrix Asphalt mix with
Lime (1% and 2%), Cement (1% and 2%) as fillers and Bagasse (0.3%) as a
stabilizing additive at optimum bitumen content.
To determine the indirect tensile strength and tensile strength ratio of Stone Matrix
Asphalt mix with Lime (1% and 2%), Cement (1% and 2%) as fillers and Bagasse
(0.3%) as a stabilizing additive at optimum bitumen content.
To conduct Indirect Tensile Fatigue test on Stone Matrix Asphalt mix with Lime
(1% and 2%), Cement (1% and 2%) as fillers and Bagasse (0.3%) as a stabilizing
additive at 25oC with variation in stress levels.
To carryout Linear Regression analysis for the data obtained from Indirect Tensile
Fatigue test conducted on Stone matrix Asphalt mix with Lime (1% and 2%),
Cement (1% and 2%) as fillers and Bagasse (0.3%) as a stabilizing additive at
25oC with variation in stress levels.
To compare the overall cost required per km for the construction of Stone matrix
Asphalt layer prepared using Lime and Cement as fillers.
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CHAPTER 2
LITERATURE REVIEW
2.1 GENERAL
Stone mastic asphalt had its origins in Germany in the late 1960s as an asphalt
resistant to damage by studded tyres. Stone mastic asphalt is a popular asphalt in Europe
for the surfacing of heavily trafficked roads, airfields and harbour areas. It is also called
split mastic asphalt in German speaking countries and elsewhere may be called split
mastic asphalt, grit mastic asphalt or stone matrix asphalt. In Australia it is normally
called stone mastic asphalt or SMA for short.
There are many definitions of SMA. APRG Technical Note 2 (1993) defines SMA as
a gap graded wearing course mix with a high proportion of coarse aggregate content
which interlocks to form a stone-on-stone skeleton to resist permanent deformation. The
mix is filled with mastic of bitumen and filler to which fibres are added in order to
provide adequate stability of the bitumen and to prevent drainage of the binder during
transport and placement.
The European definition of SMA (Michaut, 1995) is a gap-graded asphalt concrete
composed of a skeleton of crushed aggregates bound with a mastic mortar.
An explanatory note is added indicating that the binder content is generally increased
because of segregation problems. These materials are not pourable. It is common
practice to use additives and/or modified binders in the manufacture of these materials
especially to allow the binder content to be raised and to reduce segregation between the
coarse fraction and the mortar.
Australian Standard AS2150 (1995) defines SMA as a gap graded wearing course
mix with a high proportion of coarse aggregate providing a coarse stone matrix filled with
a mastic of fine aggregate, filler and binder.
The BCA (1998) defines SMA as a gap graded bituminous mixture containing a high
proportion of coarse aggregate and filler, with relatively little sand sized particles. It has
low air voids with high levels of macro texture when laid resulting in waterproofing with
good surface drainage.
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problems of cracking and rutting due to repeated traffic loads. Hence one needs to address
these problems in order to improve the performance of flexible pavements.
The layered pavement structure transmits vertical or compressive stresses to the lower
layers by grain to grain transfer through the points of contact in the granular structure
with strong graded aggregates and should transfer the compressive stresses to a wider
area. In light of the above factors, it can be learnt that bituminous mix is one of the best
flexible pavement layer materials.
Bituminous mix is generally used as a surface course and wearing course in flexible
pavements since it is necessary that the wearing course must provide a smooth riding
surface that is dense and at the same time take up wear and tear due to traffic.
2.6 A LABORATORY STUDY OF BITUMINOUS MIXES USING A NATURAL
FIBRE (7)
Debashish Kar et.al, (2012) investigated the comparison between BC and SMA Mix
with varying binder content (4-7%) and varying the fibre content (0.3-0.5%). In this paper
Marshall Properties of BC mixes using three different types of fillers without fibre (fly-
ash, cement, stone dust). Marshall Properties of BC mixes with fly ash and sisal fibres.
Marshall Properties of SMA mixes with fly ash and sisal fibres as stabilizer. Evaluation of
SMA and BC mixes using different tests like Drain Down test, Static Indirect Tensile test,
and Static Creep test.
Coarse aggregates consisted of stone chips collected from a local source, up to
4.75 mm IS sieve size. Fine aggregates, consisting of stone crusher dusts were collected
from a local crusher with fractions passing 4.75 mm and retained on 0.075 mm IS sieve.
Aggregate passing through 0.075 mm IS sieve is called as filler. Here cement, fly ash and
Stone dust are used as filler. Here 60/70 penetration grade bitumen is used as binder for
preparation of Mix. Here sisal fibre is used as additive whose length is about 900 mm.
and diameter varied from 0.2 to 0.6 mm.
The mixes were prepared according to the Marshall procedure specified in ASTM
D1559. For BC and SMA the coarse aggregates, fine aggregates and filler were mixed
according to the adopted gradation. First a comparative study is done on BC by taking
three different type of filler i.e. cement, fly ash, stone dust. Here Optimum Binder
Content (OBC) was found by Marshall Test where binder content is very from 0% to 7%.
Then Optimum Binder Content (OBC) and Optimum fibre Content (OFC) of both BC and
SMA was found by Marshall Method where binder content is very from 0% to 7% and
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fibre content is vary from 0.3% to 0.5%. The sisal fibres after being cut in to small pieces
(15-20 mm) were added directly to the aggregate sample in different proportions. The
mineral aggregates with fibres and binders were heated separately to the prescribed
mixing temperature. The temperature of the mineral aggregates was maintained at a
temperature 10C higher than the temperature of the binder. Required quantity of binder
was added to the pre heated aggregate-fibre mixture and thorough mixing was done
manually till the colour and consistency of the mixture appeared to be uniform. The
mixing time was maintained within 2-5 minutes. The mixture was then poured in to pre-
heat Marshall Moulds and the samples were prepared using a compactive effort of 75
blows on each side. The specimens were kept overnight for cooling to room temperature.
Then the samples were extracted and tested at 60C according to the standard testing
procedure.
There are several methods to evaluate the drain-down characteristics of
bituminous mixtures. The drain down method suggested by MORTH (2001) was adopted
in this study. The loose un-compacted mixes were then transferred to the drainage baskets
and kept in a pre-heated oven maintained at 150C for three hours.
Indirect tensile test is used to determine the indirect tensile strength (ITS) of
bituminous mixes. In this test, a compressive load is applied on a cylindrical specimen
(Marshall Sample) along a vertical diametrical plane through two curved strips the radius
of curvature of which is same as that of the specimen.
Static Indirect Tensile Strength test was conducted using the Marshall Test
apparatus with a deformation rate of 51mm per minute. A compressive load was applied
along the vertical diametrical plane and a proving ring was used to measure the load.
Perspex water was prepared and used to maintain constant testing temperature. Two
loading strips, 13 mm wide, 13 mm deep and 75 mm long, made up of stainless steel were
used to transfer the applied load to the specimen. The inside diameter of the strip made
was same as that of a Marshall sample (102 mm) the static indirect tensile test being
carried out on a specimen. The sample was kept in the water bath maintained at the
required temperature for minimum 1/2 hours before test. The Perspex water bath
maintained at the same test temperature was placed on the bottom plate of the Marshall
apparatus. The sample was then kept inside the Perspex water bath within the two loading
strips. Loading rate of 51 mm/minute was adopted.
Addition of 0.3% of fibre not only increases the stability value but also binder
quantity decreases. If binder content is more then it causes drain down of binder in mixes.
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Hence for SMA OFC is taken as 0.3%. Drain Down value is more for SMA Mix than BC
Mix because of more percentage of bitumen.
Indirect Tensile Strength Test value decreases with increase in temperature and for
a particular binder, when fibre is added to the mix it increases. From ITS test results it is
concluded that tensile strength of SMA Mix is more than BC Mix.
From Static Creep Test it is concluded that by addition of fibre to BC and SMA
mixes deformation reduced.
Generally by adding 0.3% of fibre properties of Mix is improved. From different
test like Drain down test, Indirect Tensile Strength and static creep test it is concluded that
SMA with using sisal fibre gives very good result and can be used in flexible pavement.
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temperature the bitumen softens, loosens its binding ability , thus attributing to the loss of
its tensile strength .The results are very high in case of 50 and very less for 40.
Ashish Talati et.al, (2014) determined the various physical properties of the bitumen
and aggregates used for SMA Mix. SMA samples were prepared by varying the binder
content in Marshall Method and Super pave Gyratory Compactor (SGC). Those
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specimens were analyzed for the density-voids and stability-flow. The optimum bitumen
content for the mix with CRMB-55 and Terrasil treated aggregates were determined.
The laboratory performances of the SMA mixes were checked for moisture
susceptibility, rutting and repeated load tests. Drainage test was conducted to check for
the binder drainage. Permeability tests were conducted to study permeable nature of SMA
mixes with CRMB-55 and treated aggregates. Moisture susceptibility tests include the
evaluation of Indirect Tensile Strength, Tensile Strength Ratio and boiling test for
stripping.
The rutting studies included the determination of rutting depth by using
Immersion Wheel Tracking Device (IWTD). Repeated load tests were carried out on
SMA samples with CRMB-55 and treated aggregates to determine its fatigue life.
Disposal of waste tires is a serious environmental concern in many countries. In order to
solve this environmental problem partly and at the same time to improve the performance
of Stone Matrix Asphalt (SMA), CRMB-55 was used for the investigation. Another
attempt of SMA Mix using an anti-stripping additive was done.
The objective of the investigations were to reduce anti-stripping by treating
aggregates using anti-stripping agents, also to study the characteristics of SMA mixes
using CRMB-55 binders and a mix using treated aggregates and VG-30 and to evaluate
the stability, flow value and volumetric properties of SMA mixes with CRMB-55 and
treated aggregates by using Marshall Method and Superpave Gyratory Compactor.
There is no specific mix design method for SMA, but there are information sheets
for initial suitability tests on hot mix asphalt. The steps of the evaluation of an appropriate
job mix formula (JMF) according to the information sheet mentioned above are as
follows: In accordance with the RFP (requirements for pavement) and with respect to its
experiences with former JMFs, mixing, paving, performance during the time of warranty,
and - last but not least - the price, the contractor selects the aggregates and the filler with
the selected material (aggregates, sand, filler, additives) and on the basis of the feedback
from other sites and JMFs, a tentative gradation is chosen. But there are requirements for
abrasion value, polish stone value, freezing-thawing-test, etc. Mixes with the required
minimum asphalt content and with three adjacent asphalt contents are prepared. Marshall
specimen are prepared at 135/145 5C and by 50 blows on each side the Marshall tests
are running for the evaluation of the air void content which must range from 3 to 5 % by
volume (i.e., depending on German climate conditions). If the required air void content is
not achieved, the following alterations of the tentative mix within the enforceable limits
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of the specifications are recommended: Change total content or content of single sizes of
crushed aggregates, Change filler content, and Change mortar content.
Drain-down test: Additives are necessary to avoid drainage of binder from the
coarse aggregates during mixing, transportation and paving. Therefore, a drain-down test
must be performed for the evaluation of the appropriate and necessary content of the
additive. On the basis of the mix design results, the contractor decides on the JMF and
submits it to the client for his approval.
In this paper about additives the description was given that though fibres,
polymers and siliceous materials are also permitted, cellulose fibres are used very
extensively. By tests, trials and by experience, it was discovered that only the use of
polymer is not adequate to avoid segregation of the gap-graded coarse aggregates and the
high bitumen content. The additive has to be a bitumen carrier; polymer as a bitumen
improver is not sufficient. All SMA-JMFs with polymers also had lower bitumen content
than required or they had additionally fibres mixed in to achieve the requirements.
Cellulose fibre shows no chemical reaction with the bitumen and it is inert to mixing
temperatures and it works excellently. Because of the performance of the cellulose fibres,
the technical assistance of the supplier and - last but not least - the relatively low price of
the fibres, the usage and the market share of the different types of additives for SMA e.g.
in Germany is as follows: Cellulose fibres 95%, the rest mineral fibres and other
additives.
It was concluded that Addition of CRMB-55and modified aggregates improves the
volumetric properties of SMA. The OBC of the SMA mixes with CRMB-55 and modified
aggregates were 6.2% and 6% using Marshall and SGC respectively. From the results, it
is clear that there is not much difference in the volumetric properties of SMA prepared
using Marshall and 80 gyrations in SGC. The SMA mixes were found to be having good
stone-on-stone contact. Addition of CRMB-55 and modified aggregates decreased the
drain down value and hence the stabilizer additives can be avoided.
The test proved that there is no stripping in the SMA Mix prepared using modified
aggregates and 10% stripping in the mix with CRMB-55. TSR was found to be more than
80% for all the SMA mixes used in the study. Higher TSR is obtained for SMA Mix using
modified aggregates which indicate better cohesive strength of this mix as compared to
SMA Mix using CRMB-55.Test results indicate that the SMA specimen using CRMB-55
is less susceptible to permanent deformation (rutting) than that with modified aggregates.
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Repeated load test results prove that the fatigue life of SMA specimen using CRMB-55
was higher as compared to the fatigue life of SMA specimen using modified aggregates.
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Noor M. Asmael et.al, (2010) evaluated the effect of additives type and content on
the performance of stone matrix asphalt mixtures. A detailed laboratory study was carried
out by preparing asphalt mixtures specimens using aggregate from Al-Nibaay, (40-50)
grade asphalt from dourah refinery and two types of fiber (carbon fiber and
polypropylene fiber) with percentages (0.2, 0.3, 0.4, 0.5%) by weight of total mix and two
types of polymer (phenol and polyethylene) with percentages (7.5, 10, 12.5, 15%) by
weight of total mix were tested in the laboratory. Compacted mixtures were tested to
evaluate the effects on SMA bulk specific gravity, maximum specific gravity, void
content, Marshall Stability, Indirect Tensile Strength (ITS) and permanent deformation.
Three different tests temperatures (20, 40,60C) were employed in the creep test and two
temperatures (5, 25 C) were used in indirect tensile test to investigate the susceptibility
of these mixes to change in temperature.
The Objective of the Study was to evaluate SMA properties for various additives
types and contents, to predict the performance of SMA mixes and to identify the influence
of modifiers on the performance of HMA. Marshall Specimens were prepared with 6% of
bitumen weight and different percentage of additives types. In order to determine optimal
additive percent, 12 specimens were produced for each additive. All specimens were
compacted with energy 50 blows. The Stability, flow and void content were considered to
obtain optimum additive content for each additive type.
The indirect tensile strength test was used to determine the tensile properties of the
asphalt concrete which can be further related to the cracking properties of the pavement.
Specimens with phenol additive resulted in higher tensile strength if compared with
polyethylene specimens. The flow value for phenol and polyethylene specimens is similar
approximately. Whereas specimens with carbon fiber additive have higher tensile strength
from polypropylene in temperature degree 50C, but polypropylene specimens have higher
tensile strength from carbon fiber in temperature degree 25C. This behavior is because
that tensile strength is related primarily to a function of the modified binder properties,
and its stiffness influence the tensile strength. Furthermore the results shows flow for
carbon fiber specimens is higher than polypropylene specimens.
Specific conclusions from this study were that the gap graded mixes are thought to
be weak in rutting resistance at high temperature. SMA mixes were found high fatigue
performance at lower temperature. The fatigue life and rutting resistance increased to a
maximum when polymer content was used. According to the study results, polymers
additives were found to be more effective than fibres additives, but it need more research
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to prove this point. SMA Mix modified with phenol additives can be used in cold and
normal temperature area, whereas SMA Mix modified with polyethylene additive can be
used in high temperature area.
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In this study four fillers namely Limestone, Ceramic Waste, Coal Fly Ash, and
Steel Slag with particle size proportion (passing 75 / passing 20 ) with three
combination of filler 100/0, 50/50, and 0/100 were evaluated for direct comparison.
The fiber selected for inclusion in the testing matrix was Cellulose Oil Palm Fiber
(COPF). This COPE is a University Putra Malaysia (UPM) initiated technology product
and have had extensive use in SMA on Malaysian roads. The COPF has been tried during
full-scale and placement on an experimental basis and has proven very effective. The
(COPF) is introduced to the mix at a dosage of 0.3% of the total weight of mix.
The method of Optimum Asphalt Content (OAC) determination based on the
Marshall Method of mix design. The filler particle size combinations (passing 75/20
micron) were mixed at three different ratios, 100/0, 50/50, and 0/100, twelve mix designs
were made with the same blend of coarse and fine aggregates to keep aggregate
angularities and mineralogical characteristics constant. The only variable in the mixtures
was the filler type and the filler proportion. The twelve mix designs were labelled as
shown in Table 4 represent four types of filler and three combinations of particle size to
produce SMA mixtures at established mixing and compacting temperatures using
Marshall Mix Design procedure to sustain medium traffic using 50 blows per side. In this
study triplicate specimens were prepared at each optimum asphalt content, a total of 36
specimens were prepared to evaluate the effects of the added filler type and particle size
on the stiffness and deformation properties of SMA mixtures.
The Indirect Tensile Stiffness Modulus (ITSM) test which is defined by BS DD
213 is a non-destructive test and has been identified as a potential means of measuring the
stiffness properties and study effects of temperature and load rate.
The aggregates, mineral fillers, asphalt binder, and cellulose fiber were tested for
compliance with the applicable specifications in the Standard Specification for
Designing Stone Mastic Asphalt. All materials were found suitable for use in SMA.
The Resilient Modulus or Stiffness Modulus is considered to be a very important
performance characteristic of the pavement. It is a measure of the load-spreading ability
of the bituminous layers and controls the level of traffic induced tensile strains at the
underside of the road base, which are responsible for fatigue cracking together with the
compressive strains induced in the subgrade that can lead to permanent deformation. The
results of resilient modulus testing of SMA mixtures showed that the medium size particle
had caused the highest stiffening effect among the other particle size proportions
regardless filler type.
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For the test temperature of 50C and based on minimum strain rate; improvement
in rutting resistance was observed for the medium particle size filler mixtures regardless
the filler type.
All the fillers used in this study play an important role in improving the rutting
resistance of SMA. These filler materials significantly enhance the potential high
temperature performance in SMA and are being encouraged for use in hot climates. As
the filler size increased (medium to large) the stiffening effect was much more significant
than the increased lubrication effect, which resulted in stiffer mixtures as indicated by the
performance of steel slag, ceramic waste, and coal fly ash. Therefore, the rut resistance
was significantly improved compared to the control filler.
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was seen that chemical treatment with aggregates is a better method to improve the
overall performance of SMA mixtures compared to bitumen modification.
The primary objective of this investigation was to prepare SMA mixtures without
any additional stabilizing material, by modifying the aggregates and bitumen with
suitable chemicals. Modification of aggregates was done by treating them with a chemical
named Terrasil and bitumen modification was achieved by the addition of another
chemical called Zycosoil. Here two types of mixtures, one with modified bitumen and the
other with treated aggregates, were prepared in SGC. It is also aimed to compare the
laboratory performance of these mixtures by conducting the volumetric and Marshall
tests, Indirect Tensile Strength (ITS) test, rutting test and moisture susceptibility test.
For preparing SMA mixtures, VG 30 bitumen and crushed granite aggregates
from nearby quarry were used. Quarry dust and lime were used as mineral filler and were
used 8% and 2% respectively, by weight of total aggregates. Commercially available
chemicals, named Zycosoil and Terrasil, were also used for this study. Zycosoil was used
to modify the conventional bitumen and Terrasil was used to treat normal aggregates.
Marshall Method of mix design for bitumen contents 5.0, 5.5, 6.0, 6.5 and 7 % by
weight of aggregates. For mixes with aggregate treatment with Terrasil conventional VG
30 bitumen without any modification was used and in the case of mixes with Zycosoil
modified bitumen, natural aggregates without any treatment was used. Compaction of
mixture was done in SGC by providing 100 gyrations for each sample.
Drain down test was conducted as per ASTM D 6390 on loose SMA mixtures with
and without modifier. Drain down was observed to be about 0.380% for SMA without any
modifier whereas it was 0.240% and 0.192% for mix with modified bitumen and treated
aggregates respectively. This showed that mixes with treated aggregates with
conventional bitumen and mixes with modified bitumen with normal aggregates satisfy
drain down criteria without any stabilizer materials. It was also seen that, aggregate
modification is the better method to control drain down compared to the use of modified
bitumen.
ITS testing is a method to measure the diametrical tensile strength of bituminous
mixture specimens, according to AASHTO 283 specification. In this method tensile
strength of compacted specimen is tested in normal conditions and also after subjecting
accelerated weathering phenomenon. Accelerated weathering is provided by conditioning
the specimens for one freeze and thaw cycle. The specimen is subjected for freezing at
153 and then keeping in hot water bath maintained at 60 for duration of 24 hrs.
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The samples were tested for tensile strength. The ratio of ITS value of conditioned
specimens to that of normal specimens is known as Tensile Strength Ratio (TSR), which
is a measure of moisture resistance of bituminous mixtures.
Boiling or stripping test was conducted as per ASTM D 3625 on loose hot
mixtures with both modified bitumen and treated aggregates at their corresponding OBC
values. Stripping was observed to be within limits for both mixtures, and was around 2
5 %. Suitable chemicals be used to modify the conventional bitumen and to treat the
normal aggregates in SMA, can control drain down of the mixture without any additional
stabilizer material.
SMA mixtures of chemically modified bitumen with normal aggregates and
chemically treated aggregates and conventional bitumen were satisfied the drain down
criteria. In a comparative study of SMA mixtures with modified bitumen and treated
aggregates, it is observed that mix with treated aggregates is performing better than the
other. Treated aggregateSMA mixtures showed better volumetric and Marshall
Properties. OBC was reduced from 6.295% in the case of modified bitumen-mix to
6.255% for treated aggregate-mixture. Even though stripping was almost same for both
mixtures, the loss in tensile strength after accelerated weathering was more for SMA with
modified bitumen, which was having a TSR of 85%, whereas it was 89% for treated
aggregates-mixture.
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All the aggregate materials used in this research were taken from the Wu-Shi
riverbed in Taiwan. The physical properties of asphalt cement with a penetration grade of
85/100. Two types of different aggregate gradations of SMA mixtures constructed in
Atlanta city of Georgia, as well as the IV b dense graded bituminous mixtures according
to the Asphalt Institute. The gradation distribution of aggregate used in this study together
with its specification limits of these three types of mixtures are also illustrated in Figures
1(a)-1(c), respectively. Here, the fine type SMA mixes have 19.05-mm (3/4-in.)
maximum aggregate size; whereas the coarse type SMA mixes have 25.4-mm (1-in.)
maximum aggregate size, respectively. The difference between these two types of SMA is
that the aggregate size of 9.53 mm (3/8 in.) is the primary portion of coarse particles in
the fine-type SMA, while in the coarse-type SMA, the coarse aggregate size is in the
range between 9.53 mm (3/8 in.) and 19.05 mm (3/4 in.). Both types of mixes have
around 30 percent passing No. 4 sieve.
The Marshall method of mix design was used to establish the optimum asphalt
content with 75 blows compact effort of heavy traffic on the asphalt concrete mixture. At
this asphalt content, the properties of three gradation mixtures were then determined.
Based upon the Marshall Design results, the 101.6-mm, 203.2-mm (4-in.8-in.) cylindrical
test specimens were prepared by compaction in three lifts placed on top of each other. All
three lifts received the similar unit compact effort as used in the mixture design, which
indicated that 80 blows were proportionally applied on each lift of the mixture. And the
specimens were prepared at optimum asphalt content and also at optimum asphalt content
0.5%, of each gradation mixture, respectively.
The Marshall mixture design results It was found that the fine type SMA showed
the highest stability value, optimum asphalt content and unit weight among these three
mixtures. This may be due to the aggregate size of primary coarse particles in the fine-
type SMA, which is smaller than the coarse-type SMA as described earlier. As a
consequence, it results in the more stone-to-stone contact area to provide more aggregate
interlock for the fine-type SMA mixtures. However, in general the difference in the
Marshall Test properties between these two types of SMA mixtures was less pronounced,
as compared with the dense graded mixtures.
In this study, only the variables of aggregate gradation and asphalt content were
considered in the influence of rest periods on the permanent deformation of asphalt
concrete mixtures. In examining how the gradation of the mixtures behave relative to one
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and another under repeated loading, the relationship of axial strain versus number of
repetitions for all mixtures at the optimum asphalt content with the various loading ratios.
It can be seen that the fine-type SMA mixtures afford the best resistance to permanent
deformation, following the coarse-type SMA and dense graded mixtures, respectively. All
the series of the test results are depicted. It is interesting to note that under the same
loading conditions, specimens with asphalt content 0.5% more than the optimum
undergoes more deformation comparing those with other two asphalt contents, regardless
of the types of aggregate gradation. Also, the permanent strain was shown to increase
with a increase in the loading ratio in this series of tests.
Based upon the experimental results of the repeated load triaxial tests, it was
found that the fine-type SMA affords the best resistance against rutting among all of three
mixtures. With viscoelastic characteristics of asphalt concrete mixtures, the energy
dissipation of the specimen during repeated loading is applied to examine the rutting
behaviour of the mixtures. It was found that fine-type SMA mixtures exhibited the least
dissipated energy associated with the smallest phase angles measured in the experiments,
which resulted in the lowest permanent deformation in the repetition loading tests.
Similar trend was found that specimens with an asphalt content 0.5% more than the
optimum undergo more deformation as compared to those with lower asphalt contents
due to the larger phase angles determined in the tests. Moreover, specimens with the
higher rest periods sustained more deformation with the larger phase angles measured in
the experiments.
Arpita Suchismita et.al, (2011) studied the resilient characteristics of SMA Mix, the
resilient properties of mixtures of stone matrix asphalt made with two types of
conventional binders namely bitumen 80/100 and 60/70, with 0.3% by weight of a non
conventional natural fiber, namely coconut fiber were utilized and the mixes were
subjected to both static and repeated load indirect tensile strength tests.
For preparation of SMA mixes, coarse aggregates up to 4.75 mm IS sieve size,
consisted of stone chips collected from a local source. Fine aggregates, consisting of
stone crusher dusts were collected from a local crusher with fractions passing 4.75 mm
and retained on 0.075 mm IS sieve. Portland slag cement (Grade 43) collected from local
market passing 0.075 mm IS sieve was used as filler material. Conventional penetration
30
grade bitumen 80/100 and 60/70, collected from a local depot was used in preparation of
mix samples. Coconut fibre/ coir fibre is a natural fibre derived from the mesocarp tissue
or husk of the coconut fruit. It is also termed as Golden Fibre due to its colour. The
individual coconut fibre cells are narrow and hollow, with thick walls made up of
cellulose. These fibres are pale when immature but later they become hardened and
yellowed as a layer of lignin gets deposited on it. Brown coir fibres are stronger as they
contain more lignin than cellulose, but they are less flexible. Coconut fibres are made up
of small threads and are relatively water proof. The peelings of ripe coconut were
collected locally, dried and neat fibres taken out manually. The lengths of such fibres were
normally in the range of 75 to 200 mm and diameter varied from 0.2 to 0.6 mm. The
tensile strength of these fibres was tested in a materials testing machine, Tinious Olsen,
UK, Model HIOKS. The average tensile strength of the fibre was found to be 70.58
N/mm2.
The mixture of coarse aggregates, fine aggregates and cement are heated to the
required temperature. Coconut fibres after being cut to small pieces approximately 3-5
mm long, (0.3%) by weight are added directly to aggregate sample and thoroughly mixed
before adding required quantity of binder. The mixes are thoroughly mixed and prepared
as per the normal Marshall procedure.
It was seen that the fibre addition results higher tensile strength. It was also
observed that for a particular binder, the tensile strength decreases with increase in
temperature. At lower temperature, the mixes with 60/70 bitumen has the higher indirect
tensile strength than 80/100 bitumen. But at higher temperatures, the mixes with 60/70
binder have the highest tensile strength as compared to the mixes with other two binders.
The parameters studied in repeated load indirect test were the resilient Poissons ratio,
resilient modulus of elasticity (MR) and fatigue life (Nf) at varying stress levels and at
three most prevailing temperatures, namely 25C, 30C and 35C. The variations of resilient
modulus of elasticity with tensile stress for different mixes at three different testing
temperatures. For mixes without fibre the decrease in MR value with stress level is more
as compared to the mixes with fibre. In case of mixes with and without fiber, at a
particular temperature and a particular stress level mixes with 60/70 bitumen have more
MR value than that with 80/100 bitumen.
It was observed that addition of fiber to the mix improves its fatigue life. At a
particular test temperature and for a particular stress difference value, the mixes with
60/70 binder have the longest fatigue life value as compared mixes with 80/100 binder. It
31
was concluded that addition of fibres results in higher tensile strength for a given bitumen
sample at a given temperature. The resilient modulus value does not change significantly
with applied tensile stress. It is also observed that a mere 0.3% incorporation of binder
results in considerable increase of the resilient moduli and fatigue life of the mixes, which
is an added advantage to the paving industry.
34
For preparation of SMA mixes, aggregate gradations according to IRC SP
79:2008for nominal aggregate size 19mm, a particular type of binder and fibre in required
quantities were mixes as per Marshall Procedure.
In this study two fillers namely Hydrated Lime and crush stone with particle size
proportion (passing 75m) with different combinations of filler were evaluated.
Conventional binder, namely 60/70 bitumen was used in this investigation to study
the effects of filler type and aggregate gradation on SMA mixes. These binders were
collected from the Hindustan Petroleum Refinery Ltd., Vizag, India
Fibres, as a stabilizing agent, are usually added to reduce the drain down of the
binder material during mixing, hauling and placing operations. Loose organic fibres, such
as cellulose, are typically added at the rate of 0.3 percent by weight of mixture.
It is recommended to use the weight to change in grade to evaluate the resistance
of aggregate particles to gradations in SMA mixes. The measurement of weight can be
very valuable procedures to evaluate the resistance of aggregate. Four of different
gradations with two types of fillers, Hydrated Lime and Crushed Stone have been tried
for preparation of mixes.
Crushed Stone has been used in the mixes had high Marshall Stability and unit
weight values more than Hydrated Lime. Hydrated Lime of SMA mixes has been
improves air voids and Moisture Susceptibility in the same gradations of samples with
Crushed Stone. The optimum binder contents are found with Hydrated Lime is less,
which is an important advantage from economy and quality point of view. It has been
observed that the drain down and moisture susceptibility characteristics have improved by
using Hydrated Lime filler in the mix. It creates multiple benefits for pavements:
1. Hydrated lime acts as mineral filler, stiffening the asphalt binder and SMA.
2. It improves resistance to fracture growth (i.e., it improves fracture toughness) at low
temperatures.
3. It favourably alters oxidation kinetics and interacts with products of oxidation to reduce
their deleterious effects.
Hydrated lime is an additive that increases pavement life and performance through
multiple mechanisms. It is also found that Crushed Stone increases the stability value and
tensile strength ratio of mixes. Both of lower and upper curve were failed to get the
optimum binder content in both types of filler used, middle curve behaviour same to
modified curve but lower in result values. From the overall discussion of the test results
on SMA mixes, it can be concluded that all the mixes made with middle curve and
35
modified curve content of both filler types perform satisfactorily and can be used in mixes
in the wearing courses of flexible pavements. However validation of the above test
results, experimental track should be laid to study the performance of pavements with
such SMA mixes.
Mohamed Sulyman et.al, (2014) the work was concerned with assisting the
interested readers to be familiarized with the paving material asphalt-modifiers obtained
from SIW by providing historical perspective on its first invention and development. The
paper has also provided highlights on common processes of asphalt mixture production. It
was also worth mentioning that there are two asphalt production technologies: the warm
mix asphalt (WMA) and hot mix asphalt (HMA) technologies, and the various advantages
of using each one. Additionally, the paper has provided the reader with an overview of a
number of case studies which were conducted by scientists and researchers for serious
attempting to reach development and capturing significant properties of incorporating
SIWs in civil engineering represented by scrap tires in form of crumb rubber (CR),
plastics (polymers) in their different forms.
In regard to the application of LDPE, another study on recycling of CR and LDPE
blend on stone matrix asphalt SMA by use of dry process was conducted [58]. The study
was planned to reduce pollutions from waste tires disposals and to investigated the
benefits of stabilizing the so-called SMA using CR and LDPE in 15% and 30% by weight
of asphalt respectively. SMA had an optimum dosage of the additives of a combination of
30% (combined combination with 30% CR & 70% LDPE) by weight of the asphalt.
Results of tensile strength test has found its ratio values to be in the range of (85 94)%
which was more than 85% as specified for a SMA mixture, while the compression
strength test values were found to be in the range of (1600 4000) kg/cm2 which has
improved longevity. Generally, the results revealed that the addition of CR & LDPE to
SMA using dry process could improve the engineering properties of SMA mixture, and
the rubber content has added a significant effect on long term performance.
39
It was concluded that the blending of recycled waste rubber tires in the form of
CRs and plastics with the asphalt requires a number of experimental factors to be
controlled and various techniques to be selected in order to reach improvement in
engineering properties of asphalt binder. The number of case studies supplied throughout
this paper was sufficient to help readers to be familiar with the different technologies
applied of producing and incorporating modifiers in asphalt mixtures that are important in
construction of roads with very qualified pavements and improved longevity and
pavement performance.
40
flakes of 16MA400 grade injection molding grade film was used as additive in SMA
mixture.
ANOVA analysis was conducted to determine the effect of CR+LDPE on
properties of SMA. In the Single- factor tests of ANOVA, rubber content was chosen as
factor and compressive strength were response respectively.
It was concluded that The Tensile strength Ratio values are found to be in the
range 85 - 94 % which is more than 85 % as specified for a SMA mixture. The
Compressive strength values are found to be in the range 1600 kg/cm2 - 4000 kg/cm2.
The Compressive strength of SMA Mix with Crumb Rubber and LDPE blend as additive
improved the longevity from the Compressive strength value. The SMA mixes designed
with available aggregates showed good stone on stone contact (VCA DRC< VCA MIX).
The 17% Voids in Mineral aggregate and 3 - 5% air voids in the mix were fulfilled as
SMA Mix design criteria.
The Drain down values was in the range of 0.04% to 0.17% by weight of the mix.
Based on the above performance, Combined Combination of Crumb Rubber and LDPE
could be used as stabilizing additive in the form of dry processing showed without
affecting the design criteria of SMA mixture. The optimum dosage of the Additive was
found to be 30 % (Combined Combination with 30% Crumb Rubber and 70 % LDPE) by
weight of the bitumen. From the results of ANOVA analysis of UCS, 30% rubber content
by weight of bitumen has significant effect on best performance. The long-term
performance of recycled CR+LDPE blend on SMA mixture using dry process will need to
be further studied.
Gatot Rusbintardjo et.al, (2014) investigated the use of oil palm fruit ash-
modified bitumen (OPFA-MB) as a binder in stone-mastic asphalt (SMA) mixtures. The
OPFA was used to take advantage of a waste by-product of the palm oil milling industry
which could help to reduce environmental pollution. Binder tests such as penetration,
softening point, viscosity, storage stability, dynamic shear rheometer (DSR), bending
beam rheometer (BBR), and the direct tension test (DTT) were conducted on both
unmodified and OPFA-modified bitumen.
41
Oil palm fruit ash (OPFA) is a by-product of palm oil milling, or the ash from
burning the mesocarp of the fruitlets. This by-product is currently disposed of as waste,
thus polluting the environment and affecting the health of the surrounding community.
Physically, OPFA is greyish in colour and becomes dark with increasing proportions of
unburned carbon.
OPFA originates from palm oil milling and consists of rough grains. The grain is
elongated-flat in shape with a maximum grain length of 6 mm. Two grain sizes were used
in this research. One was very fine with a uniform grain size of 75 m resulting from
grinding the original OPFA and sieving through sieve size 75 m, and the other resulted
from sieve analysis using a maximum sieve size of 300 m and a minimum size of 75
m. OPFA with a uniform grain size of 75 m is known as Fine-OPFA, and OPFA with a
maximum grain size of 300 m is known as Coarse-OPFA.
OPFA was mixed in increments of 2.5% by weight (to a maximum of 10%) with
bitumen at a mixing temperature of 160C, a mixing time of 60 minutes and a stirring
speed of 800 revolutions per minute (rpm). The mix of OPFA and bitumen was called
OPFA-Modified Bitumen (OPFA-MB). Based on the particle size of OPFA and its content
in the bitumen, there were four OPFA-MBs with Fine-OPFA and four OPFA-MBs with
Coarse-OPFA. The four Fine-OPFA-MBs (hereafter abbreviated as F-OPFA-MB), namely
2.5, 5, 7.5 and 10% of F-OPFA-MBs, and the four Coarse-OPFA-MBs (hereafter
abbreviated as C-OPFA-MB), namely 2.5, 5, 7.5 and 10% of C-OPFA-MBs, were used
for further study.
In this study, stone mastic asphalt-14 (SMA-14) mixes were designed using the
Marshall Mix design, based on the Malaysian PWD Specification [10]. The Marshall
Specimens were prepared in accordance with ASTM D1559 [32], using 50 blows per face
compaction standard. The Malaysian Specification of 75 compaction blows was not used,
since they would tend to break down the aggregate more and would not result in a
significant increase in density over that provided by 50 blows. The gradation of the
aggregate used is given in Table 4. Five different bitumen contents, namely 5, 5.5, 6, 6.5
and 7% (by weight of aggregates) were used to determine the optimum bitumen content
(OBC). Three samples were prepared for each binder contents. The Marshall Stability and
specific gravity test were then conducted on each sample. The specific gravity of the
sample was used to determine the void content of the mix (VMA) of SMA mixes. The
OBC was found to be around 5.8% from the mix design used for the SMA-14 mixtures.
After obtaining the OBC, laboratory tests were carried out on SMA-14 specimens using
42
F-OPFA-MBs and C-OPFA-MBs, control bitumen, and PG 76-22 binder. Several
performance tests conducted on SMA mixes are discussed in the following sections.
The indirect tensile test to determine the resilient modulus of bituminous mixtures
was performed in accordance with ASTM D412382 [33]. The specimens used in this
study were Marshall Specimens, which have an average height of 70 mm and an average
diameter of 101.6 mm. The test was conducted at 5, 25, and 40C (1C) at a loading
frequency of 0.5 and 1 Hz for each test temperature and load duration of 0.1 second. The
test was conducted by applying compressive loads with a haversine waveform. The load
was applied vertically in the vertical diametric plane of a cylindrical specimen. The
resulting horizontal deformation of the specimen was measured and an assumed Poissons
ratio was used to calculate the resilient modulus. For a test temperature of 5C, the
Poissons ratio was assumed to be 0.25, and for 25 and 40C, the Poissons ratio was
assumed to be 0.40 [30]. The values for the vertical and horizontal deformation were
measured by linear variable differential transducer (LVDT). The total resilient modulus
was calculated using the total recoverable deformation, which includes both the
instantaneous recoverable and the time-dependent continuing recoverable deformation
during the unloading and rest period portion of one cycle.
The static uniaxial creep test was the simplest method of assessing the resistance
to permanent deformation or rutting. The Marshall specimen was used in the static
uniaxial creep test. Its dimensions were similar to those of the specimen used in the
indirect tensile resilient modulus test. The test was conducted in accordance with the
Texas Department of Transportation Standard Test, TxDOT Designation Tex-231-F [34].
The specimen was placed in a controlled temperature chamber maintained at a test
temperature of 40C for three to five hours prior to the start of the test. The specimen was
then mounted on a compression head and the temperature was maintained at 40C. Three
cycles of a 125 lb (556 N) square wave preload were applied at one-minute intervals
followed by a one-minute rest period for each cycle. This was to allow the loading plates
to achieve more uniform contact with the specimen. A 125 lb (556 N) load was then
applied to the specimen for one hour. At the end of one hour the load was removed,
allowing the specimen to rebound for ten minutes. During the entire loading and
unloading time, the applied load was monitored and recorded, resulting in vertical
deformation for each LVDT. The average deformation for each specimen was calculated
by averaging the readings from the two LVDT. The average deformation values were
converted to strain using the ratio of permanent deformation to thickness of the specimen.
43
It was concluded that Based on the PI and PVN results, adding OPFA to the
bitumen improves the temperature susceptibility of bitumen. Only 50% of OPFA-MBs
show that OPFA cannot be dissolved into bitumen, but other tests show that its presence
strengthens the properties of bitumen. The OPFA does not dissolve in bitumen due to the
fact that it has higher specific gravity values compared to bitumen. The findings show that
OPFA added to bitumen at certain percentages improves binder durability in terms of
rutting and fatigue cracking at high and low temperatures, respectively. In addition, the
use of OPFA-MB in SMA-14 mixes improves the resistance to low temperature cracking,
improves the Marshall Stability value, and minimizes rutting at high temperatures
compared to SMA-14 mixed with conventional bitumen. However, the use of PG 76-22
binder results in a stronger mixture compared to SMA-14 mixed with OPFA-MB. The
presence of OPFA-MB improves binder adhesion to the aggregates in SMA-14.
44
Cellulose oil palm fiber is used in SMA as a stabilizer to prevent drain-down of
the asphalt binder during construction. The Cellulose Oil Palm Fiber (COPF) used in this
study is a University Putra Malaysia (UPM) initiated technology product (Muniandy,
2004). Four filler types namely Limestone Dust (LSD), Ceramic Waste Dust (CWD),
Coal Fly Ash (CFA), and Steel Slag Dust (SSD). The filler content of 10% by total weight
of aggregate with three particle size proportions; (100 passing 75m, 50/50 passing 75/20
m, and 100 passing 20 m) were evaluated for direct comparison in this study. Fillers
were crushed and ground to pass the standard sieve size 0.075 mm and 0.02 mm.
Resilient modulus is a relative measure of mixture stiffness and load distribution
ability; higher resilient modulus values lead to stiffer mixtures with higher load
distribution ability. The Resilient Modulus was determined from tests on cylindrical
specimens for each mixture at designed bitumen contents in the indirect tension mode.
The frequency of load application used was 1 Hz, with load duration of 0.1 second to
represent field conditions and a resting period of 0.9 second. Constant test temperature
was maintained using an environmental air chamber. Each specimen was placed inside
the chamber at the set temperature for two hours before testing. The test was carried out at
temperature of 25 C using Material Testing Apparatus (MATTA) in accordance with
ASTM D 4123.
The reported improvement in the engineering properties of the paving mixtures
containing ceramic waste, coal fly ash, and steel slag can be attributed to the bonding and
cementations properties of the fillers. This tends to increase the viscosity of the filler-
asphalt mastic and the particles texture of the fillers which tends to increase the frictional
resistance among the aggregate particles an increase in the stability of the mix. From the
investigation reported in this study, using different types of fillers with different particle
size, the following conclusions can be summarized as follow:
Filler type and particle size plays an important role on the engineering properties
of the asphalt mixtures. The filler component, in addition to filling the voids, interacts
with the binder present in the mix making it stiff and brittle. The change in mix properties
is very much related to the properties of the filler. The major finding of this study, is that
ceramic waste and steel slag as a filler were found to be effective in improving the
Marshall Stability, Resilient Modulus, and Marshall Stiffness Index or Marshall Quotient
(MQ) as compared to limestone filler. Coal Fly Ash had the lowest optimum asphalt
content. On the other hand, it had little improvement in Marshall Stability and the
Resilient Modulus value compared to the reference filler.
45
In this study; a general trend was observed that, the properties of the asphalt-filler
mastics and SMA mixtures increased by increases the filler particle size at a given
asphalt/filler ratio regardless filler type. The results of the laboratory tests on the ceramic
waste and steel slag fillers were found to improve the overall mixture properties. The use
of these special filler improves the pavement performance, thus reducing the maintenance
and rehabilitation cost of the pavement. It can be concluded that utilization of industrial
and by-product wastes in SMA results in the improvement of the engineering properties
and reduction in the optimum asphalt content. The reduction in optimum asphalt content
results in significant cost saving.
49
2.36 LITERATURE SUMMARY
From the literature review it showed that Stone Matrix Asphalt is an ideal paving
mixture for Indian conditions especially to our Highways. Literature shows that it has
been possible to improve the performance of bituminous mixtures used in the surfacing
course with the help of various types of additives like fibres, polymers and waste
materials. Synthetic fibres are conventionally used in the construction of Stone Matrix
Asphalt. They are not manufactured in India and are imported at a high cost. The
excessive use of synthetics has led to environmental pollution. This ecological crisis has
necessitated the use of bio-renewable resources and plant fibres. Resources in terms of
materials consumed for construction and maintenance of roads are very scarce and
limited. Therefore, there is an urgent need to identify new technologies that can work well
with alternative resources such as agro based materials and renewal of existing resources
without affecting the performance. Some limited studies have been reported on the use of
natural fibres and waste materials in SMA. This will result in improving the
characteristics and service life of bituminous surfacing, eventually leading to
conservation of construction materials.
It can also be concluded that the Conventional bituminous pavements have less
strength, durability and longevity than SMA. There are several factors for which we can
say that SMA is better than many conventional mixes. SMA provides excellent resistance
to rutting due to slow, heavy and high volume traffic, resistance to deformation at high
pavement temperatures, it also improves skid resistance, reduces noise when compared to
conventional alternative pavement surfaces. SMA also shows improved resistance to
fatigue effects and cracking at low temperatures, also increases durability, and reduces
permeability and sensitivity to moisture.
50
CHAPTER 3
EXPERIMENTAL INVESTIGATION
3.1 MATERIALS
3.1.1 Coarse and Fine Aggregates
Aggregates form the major portion of bituminous mixes and play a major role in
the performance of a bituminous mix. Aggregates constitute of approximately 88% to
96% by weight and volume of the total mix, affecting the stability and working properties
of a mix. Aggregates form the major constituent of road construction materials. Since
they have to bear the brunt of traffic, they should be strong enough to resist the
degradation and should have enough structural stability which is offered by the
mechanical interlock of aggregate in the layer. IS 2386-1963 gives the methods of tests
for aggregates in road construction. Aggregates used are mainly divided in to coarse and
fine aggregates based on their size. Aggregates retaining on 2.36mm sieve are referred as
coarse aggregates and aggregates passing on 2.36mm sieve size are referred as fine
aggregates. Specific gravity of coarse aggregates and fine aggregates is 2.68 and 2.69
respectively. The test results obtained are presented in Table 3.1.
Table 3.1 Test results of aggregates
51
Flakiness and Elongation Index
28.03% Max 30%
(Combined), %
Cement of MORT&H ( V
Lime
Revision)
Specifications
0.6 100 100
100
0.3 100 95-100
100
0.075 98.85 85-100
97.65
52
Table 3.3: Physical Property of Filler Materials
Filler
Property
Lime Cement
Colour White Gray
3.1.3Binder
Bitumen is a non-crystalline viscous material black/ dark brown in colour, which is a
hydrocarbon material of either natural or pyrogenous origin, found in gaseous, liquid,
semisolid or solid form and is completely soluble in Carbon disulphide and Carbon Tetra
chloride. Bituminous materials are very commonly used in highway construction because
of their binding and water proofing properties. Bitumen acts as a binder in Stone Matrix
Asphalt mix. As per IRC SP: 53-2010 in this work Polymer Modified Bitumen-40 is used
as binder. The various tests are conducted on the Polymer Modified Bitumen-40 and the
results are shown in Table 3.3.
Table 3.3 Test results of Polymer Modified Bitumen-40
Requirements as per
Particulars of tests Test Results
IRC SP: 53-2010
Penetration at 25C, 100gm, 5 Seconds,
39 30-50
0.1mm
Softening point (Ring & Ball), C 68 Min 60
54
for Stone Matrix Asphalt mixes as per MORT&H (V revision) specifications. The
gradation values are presented in Table 3.5
Table 3.5: Aggregate Gradation for Stone Matrix Asphalt mix (13mm SMA) as per
MORT&H (V revision) Specifications
Obtained gradation
Sieve Size in
% Passing (Specified) ( Sieve analysis results),
mm
% Passing
19 100 100
13.2 90-100 95
4.75 20-28 24
2.36 16-24 20
1.18 13-21 17
0.600 12-18 15
0.300 10-20 15
0.075 8-12 10
57
The test is performed as follows:
Fill the container with aggregate up to one third of its height, level the surface of
the poured aggregate using fingers, and then tamp the layer down with 25 strokes of the
tamping rod, taking care to evenly distribute the strokes over the surface and avoiding
hitting the bottom of the container. Having completed the tamping of the first layer of
aggregate, fill the container with a second layer of aggregatethis time up to two thirds
of its heightand repeat the tamping procedure. Having completed tamping the second
layer of aggregate, fill the container with aggregate to overflowing and continue tamping
down as previously described. Even out the aggregate using fingers or scrape away any
excess aggregate with a rod so that protruding coarse particles will compensate for any
gaps between them. Determine the mass of the compacted aggregate by weighing the
measure with aggregate and weighing it empty. Calculations are done using following
formula:
Calculate the bulk density of an aggregate according to the formula
(GT )
M=
V
Where, M=Bulk density of the coarse aggregate, kg/m3
G=Mass of a cylindrical measure and aggregate, kg
T=Mass of a cylindrical measure, kg
V=Volume of a cylindrical measure, m3
Calculate the void content in a compacted aggregate according to the formula
( G ca x w ) M
VCADRC = [ ] x 100
(G ca x w)
58
3.5 DRAIN DOWN TEST
Drain down is considered to be that portion of the mixture (fines and bitumen) that
separates itself from the sample as a whole and flows downward through the mixture.
Drain down test is more significant for SMA mixtures than for conventional dense-graded
mixtures. It can be used to determine whether the amount of drain down measured for a
given bituminous mixture is within the specified acceptable levels. This test is primarily
used for mixtures with high coarse aggregate content (the internal voids of the uncompact
mix are larger, resulting in more drain down) such as Stone Matrix asphalt and porous
asphalt (open-graded friction course). Potential problems with SMA mixtures are
drainage and bleeding. Storage and placement temperatures cannot be lowered to control
these problems due to the difficulty in obtaining the required compaction. Therefore,
stabilizing additive has been added to stiffen the mastic and thereby reducing the drainage
of the mixture at high temperatures and to obtain even higher binder contents for
increased durability.
SMA mixtures exhibited a very high bitumen binder film thickness (6-7% by
weight of mix). This high binder content and the filler content (as compared to that of
dense-graded HMA) lead to higher susceptibility for the bitumen binder to drain off the
aggregate skeleton (i.e., drain down) in SMA mixtures. Irregular distribution of bitumen
binder due to its drain down can lead to raveling and fat spots.
Test procedure
In the present study, the SMA mixtures obtained at optimum binder content are
checked for drain down. The mass of loose SMA mixture sample and the initial mass of
the pan is determined to the nearest 0.1 g. The loose SMA sample is then transferred and
placed into the wire basket without consolidating or disturbing it. The basket is placed on
the pan and the assembly afterward is placed in the oven (170 C) for 1hour. After the
sample has been in the oven for 1 hour, the basket and the pan is removed and the final
mass of the pan is determined and recorded to the nearest 0.1 g. The Drain down of the
mixture can be calculated as follows,
DC
Drain down, % = [ B A ] x 100
Where, A = Mass of empty wire basket, g
B = Mass of wire basket + sample, g
C = Mass of empty catch tray, g
59
D= Mass of tray + drained material, g
The drain down test is conducted at optimum bitumen content for each type and
percentages of mineral filler used.
The Indirect Tensile Test is performed by loading a cylindrical specimen with a single
or repeated compressive load, which acts parallel to and along the vertical diametric
plane. This loading configuration develops a relatively uniform tensile stress
perpendicular to the direction of the applied load and along the vertical diametric plane,
which ultimately causes the specimen to fail by splitting along the vertical diameter. The
Indirect Tensile Test is one of the most popular tests used for hot bituminous mixture
characterization in evaluating pavement structures. Indirect Tensile test setup and
mechanism is shown in Fig. 3.1 and Fig 3.2
60
(A) Indirect Tensile Test during loading (B) Indirect Tensile Test at failure
2xP
x = x D xt --------------------- Eq 3.1
61
It is well known fact that the continuous contact of water with pavement causes
premature pavement damage. Moisture induced distress may be regarded as one of the
most significant problem for bituminous pavement.
Moisture susceptibility of bituminous mixes can be quantified by several methods
such as stripping of binder from aggregate, retained stability, tensile strength ratio and
ratio of resilient modulus. In the present investigation an attempt was made to study the
effect of moisture by conducting tensile strength ratio and retained stability on Stone
Matrix Asphalt mixes prepared with three different aggregate gradations.
Test Procedure for conducting Tensile Strength Ratio test (TSR)
Similar to Indirect Tensile Strength test procedure, Marshall Specimens are prepared
at optimum bitumen content for the gradations as per ASTM D-1075
Samples were divided into two group i.e. Group-1 and group-2.
The Group-1 of specimens are tested in a dry condition (unconditioned state), while
the Group-2 specimen are tested in soaked condition.
For the Group-1, specimens are treated as control without any conditioning and then
all specimens are tested for ITS at test temperature of 251C (by storing them in a
water bath maintained at the test temperature for not less than 2 hour) under the
loading rate of 50 mm per minute. The load at failure is recorded and the indirect
tensile strength is computed using the equation 3.1.
The average value for the indirect tensile strength of Group-1 set is calculated.
For the Group-2, specimens are placed in water bath maintained at 60C for 24
hours. Then specimens were transferred to the second water bath maintained at
25C stored for 2 hours.
All the specimens are tested for ITS at test temperature of 251C and indirect
tensile strength for the saturated conditioned specimens is computed.
The indirect tensile strength ratio (TSR) can be determined using the following
relation
Indirect Tensile Strength of Conditioned specimens
TSR = X 100
Indirect Tensile Strength of Unconditioned specimens
cs
TSR = x 100 --------- Eq.3.1
ucs
62
The stress levels were decided based on the Indirect Tensile Strength Test conducted on
cylindrical specimens of Stone Matrix Asphalt. Indirect Tensile Fatigue test setup is
shown in Fig. 3.4.
Indirect Tensile Fatigue Test apparatus
Salient features of the equipment
Capacity - 2 Tons
Load type - Half Sine
Major component - LVDT (Linear Variable Differential Transducers)
- Load cell
- Loading frame
- Temperature controlled chamber
- Position controller
- Data acquisition system
The equipment was designed and developed by Spanktronics Ltd. was used to
carry out the Indirect Tensile Fatigue Test. A thermostatically controlled unit was used to
regulate the temperature during the test. A load cell is provided for applying the required
magnitude of load applied parallel to and along the vertical diametrical plane of the
Marshall specimen controlled by a servo valve operated by a computer. The load is
applied over the specimen through two metal strips of 12.5mm width and radius of
63
curvature equal to that of the specimen. The horizontal and vertical deformation of the
specimen due to application of load during the experiment was measured using two sets
of LVDTs. The equipment has a facility to apply the repetitions in half sine waveform.
The recording job of the applied load, deflection of both horizontal and vertical LVDTs
for every cycle and the total number of repetitions before failure for each individual test
was done by a data acquisition system which comprises of a computer and software
developed by Spanktronics Ltd.
The frequency of loading and rest period can also be fixed as per the requirement.
In this present investigation the loading frequency adopted was 2 Hz (2 cycles per
second) and the rest period was 0.2 seconds.
3.6.1 Procedure for conducting Indirect Tensile Fatigue Test
Marshall Specimens of Stone Matrix Asphalt mix were prepared at Optimum
Bitumen Content using Lime (1% and 2%) and Cement (1% and 2%) as filler materials
and Bagasse as stabilizing additive. Before testing the specimens were conditioned at the
test temperature in water for 2 hours in a temperature controlled water bath. After the
conditioning period of two hours the specimen is placed in the testing mould between the
two metal strips used for applying the load on to the specimen with care to see that the
load is applied exactly one the center of the specimen after which the bolts are locked up
to hold the specimen intact at its position. The horizontal and vertical LVDTs are fixed in
their respective positions. The loading jack is brought down to just rest on the metal strip
used to transfer the load on to the specimen. The data acquisition software specially
designed using Visual Basic program was used for the repeated load testing. The software
declares the specimen failed when the LVDTs reach the specified limit and saves the data
in a excel format.
The data provided by the software in an excel format was analyzed to determine
Resilient Modulus, Applied Stress, and Initial Tensile Strain for all the specimens tested
using the following equations:
2xP
Tensile stress, x = x D xt --------------------------Eq-3.1
64
D= diameter of the specimen, mm
t = thickness of the specimen, mm
P x (0.27+ )
Resilient Modulus, MR = ------------------------Eq-3.2
HR x t
x (1+3 )
Initial tensile strain, = --------------------------------Eq-3.
MR
CHAPTER 4
ANALYSIS OF DATA
4.1 GENERAL
65
Marshall Stability test was conducted on Stone Matrix Asphalt mix with Lime
(1% and 2%) and Cement (1% and 2%) as a filler material and Bagasse as stabilizing
additive (0.3% by weight of mix) and PMB-40 as binder to determine optimum bitumen
content, Marshall Stability, flow, bulk density, total air voids, voids in mineral aggregates
and voids filled with bitumen at mixing temperature (160 oC) and compaction temperature
(140oC) respectively. The results obtained are compared to check effect of stabilizing
additive Bagasse and to determine the type of filler which gives maximum stability at
optimum bitumen content
The two major features of Marshall Mix Design method are
Density-Void Analysis.
Stability-Flow Tests.
4.2 MARSHALL PROPERTIES OF STONE MATRIX ASPHALT MIX WITH
LIME (1%) AS FILLER MATERIAL AND BAGASSE (0.3%) AS
STABILIZING ADDITIVE
The Marshall properties of the Stone Matrix Asphalt mix with Lime (1%) as filler
material and stabilizing additive (0.3%) at 160C mixing temperature and 140C
compaction temperature are presented in Table 4.1.
Table 4.1: Marshall Properties of Stone Matrix Asphalt mix with Lime (1%) as filler
material
Voids in Voids
Bitumen Marshall Flow, Bulk Total air Mineral filled
content, stability, mm density, voids, % Aggregates with
% kg g/cc , bitumen,
% %
5
5.5
6.0
6.5
Marshall Properties of the Stone Matrix Asphalt mix with Lime (1%) as filler
material and Bagasse (0.3%) as stabilizing additive at 160 C mixing temperature and
140C compaction temperature are shown graphically, from Fig 4.1 to Fig 4.5
66
Object 23
Object 25
67
Object 27
Object 30
68
Object 32
The Optimum Bitumen Content (OBC) for the mix design is found by taking the
average value of the following three bitumen content found from the graphs of the test
results.
1. Bitumen content corresponding to maximum Stability Value.
2. Bitumen content corresponding to maximum unit weight/ bulk density.
69
Table 4.2: Marshall Properties of Stone Matrix Asphalt mix prepared at Optimum
Bitumen Content with Lime (1%) as filler material
Requirements as
Requirements as per
per IRC SP: 53-
SL Test Table 500-38 of
Marshall Properties 2010
No. Results MORT&H (V revision)
Specifications for
Specifications
wearing course
Optimum Bitumen
1 5.90 Min 5.8 Min 5.6
Content, %
2 Marshall Stability, kg 1320 Min 900* Min 1200**
Table 4.3: Marshall Properties of Stone Matrix Asphalt mix with Cement (1%) as
70
filler material
Bitumen Marshall Flow, Bulk Total air Voids in Voids
content, stability, mm density, voids, % Mineral filled
% kg g/cc Aggregates with
, bitumen,
% %
5
5.5
6.0
6.5
Marshall Properties for the Stone Matrix Asphalt mix with Cement (1%) as
mineral filler and Bagasse (0.3%) as stabilizing additive at 160 C mixing temperature and
140C compaction temperature are shown graphically, from Fig 4.6 to Fig 4.10
Object 34
71
Object 36
Object 38
72
Object 40
Object 42
74
Table 4.5 Marshall Properties of Stone Matrix Asphalt mix with Lime (1%) and
Cement (1%) as mineral filler at optimum bitumen content
Marshall Properties for the Stone Matrix Asphalt mix with Lime (1%) and Cement
(1%) as mineral filler and Bagasse (0.3%) as additive at 160 oC mixing temperature and
140oC compaction temperature are graphically compared and shown from Fig 4.11 to
4.15
Object 44
75
Object 46
Object 48
76
Object 50
Object 52
77
4.3 MARSHALL PROPERTIES OF STONE MATRIX ASPHALT MIX WITH
LIME (2%) AS FILLER MATERIAL AND BAGASSE (0.3%) AS
STABILIZING ADDITIVE
The Marshall properties of the Stone Matrix Asphalt mix with Lime (1%) as filler
material and stabilizing additive (0.3%) at 160C mixing temperature and 140C
compaction temperature are presented in Table 4.6.
Table 4.6 Marshall Properties of Stone Matrix Asphalt mix with Lime (2%) as
filler material
Voids in Voids
Bitumen Marshall Flow, Bulk Total air Mineral filled
content, stability, mm density, voids, % Aggregates with
% kg g/cc , bitumen,
% %
5
5.5
6.0
6.5
Marshall Properties for the Stone Matrix Asphalt mix with Lime (2%) as filler
material and Bagasse (0.3%) as stabilizing additive at 160 C mixing temperature and
140C compaction temperature are shown graphically, from Fig 4.16 to 4.20
78
Object 54
Object 56
79
Object 58
Object 60
80
Object 62
The Optimum Bitumen Content (OBC) for the mix design is found by taking the
average value of the following three bitumen content found from the graphs of the test
results.
1. Bitumen content corresponding to maximum Stability Value.
2. Bitumen content corresponding to maximum unit weight/ bulk density.
81
2 Marshall Stability, kg 1320 Min 900* Min 1200**
Table 4.8 Marshall Properties of Stone Matrix Asphalt mix with Cement (2%) as
filler material
Voids in Voids
Bitumen Marshall Flow, Bulk Total air Mineral filled
content, stability, mm density, voids, % Aggregates with
% kg g/cc , bitumen,
% %
5
5.5
6.0
6.5
82
Marshall Properties for the Stone Matrix Asphalt mix with Cement (2%) as
mineral filler and Bagasse (0.3%) as stabilizing additive at 160 C mixing temperature and
140C compaction temperature are shown graphically, from Fig 4.21 to 4.25
Object 64
Object 66
83
Object 68
Object 70
84
Object 73
The Optimum Bitumen Content (OBC) for the mix design is found by taking the
average value of the following three bitumen content found from the graphs of the test
results.
1. Bitumen content corresponding to maximum Stability Value.
2. Bitumen content corresponding to maximum unit weight/ bulk density.
Table 4.9 Marshall Properties of Stone Matrix Asphalt mix at Optimum Bitumen
Content with Cement (2%) as filler material
Requirements as
Requirements as per
per IRC SP: 53-
SL Test Table 500-38 of
Marshall Properties 2010
No. Results MORT&H (V revision)
Specifications for
Specifications
wearing course
1 Optimum Bitumen 5.90 Min 5.8 Min 5.6
85
Content, %
Table 4.10 Marshall Properties of Stone Matrix Asphalt mix with Lime (2%) and
Cement (2%) as mineral filler at optimum bitumen content
Object 75
Object 77
87
Object 79
Object 82
88
Object 84
89
Table 4.12 Drain Down of Stone Matrix Asphalt Mix with Lime and Cement as
fillers
Requirements as
Fillers (1%) Fillers (2%) per Table 500-38
Drain down
MORT&H (V
properties
Lime Cement Lime Cement Revision)
Specifications
Drain down, (%) 0.124 0.158 0.00 0.00 0.30
Table 4.13: Indirect Tensile Strength of Stone Matrix Asphalt Mix with Lime and
Cement as filler materials
Figure 4.31: Indirect Tensile Strength of Stone Matrix Asphalt Mixes Prepared Using
Stone Dust and Cement as Filler Materials
90
Table 4.14: Tensile Strength Ratio of Stone Matrix Asphalt Mix with Lime and
Cement as filler materials
91
Object 86
Fig. 4.32 Fatigue Life v/s Stress Level of Stone Matrix Asphalt Mix with Lime (1%)
as
filler
Object 88
Fig. 4.33 Fatigue Life v/s Tensile Stress of Stone Matrix Asphalt Mix with Lime (1%)
as filler
92
Object 90
Fig. 4.34 Fatigue Life v/s Resilient Modulus of Stone Matrix Asphalt Mix with Lime
(1%) as filler
Object 93
Fig. 4.35 Fatigue Life v/s Initial Tensile Strain of Stone Matrix Asphalt Mix Lime
(1%) as filler
93
Table 4.16 Indirect Tensile Fatigue Test on Stone Matrix Asphalt Mix with Cement
(1%) as Filler at 25oC
Initial
Resilient Fatigue
Stres Height of Tensile Resilient Tensile
Load, Horizontal Life,
s specimen Stress, Modulus strain,
N Deformatio No. of
level , mm MPa , MPa Micro
n, mm cycles
strain
0.0686
10% 720 65.67 0.02398 283.457 496.778 3469
9
0.0680
10% 720 66.30 0.02410 279.330 499.320 3480
4
0.0683
281.394 498.049 3475
6
0.1353
20% 1440 66.67 0.03431 390.337 710.683 2405
2
0.1374
20% 1440 65.66 0.03648 372.708 755.747 2418
0
0.1363
381.523 733.215 2412
6
0.2019
30% 2160 67.00 0.04066 491.587 842.292 1128
8
0.2047
30% 2160 66.10 0.04154 487.687 860.588 1143
3
0.2033
489.637 851.440 1136
5
0.2747 1049.53
40% 2880
65.67 6 0.05066 536.680 0 823
0.2683 1002.67
2880
40% 64.30 1 0.04840 573.730 0 811
0.2715 1026.10
3 555.205 0 817
94
Object 96
Fig. 4.36 Fatigue Life v/s Stress Level of Stone Matrix Asphalt Mix with Cement
(1%) as filler
Object 98
Fig. 4.37 Fatigue Life v/s Tensile Stress of Stone Matrix Asphalt Mix with Cement
(1%)
as filler
95
Object 100
Fig. 4.38 Fatigue Life v/s Resilient Modulus of Stone Matrix Asphalt Mix with
Cement (1%) as filler
Object 103
Fig. 4.39 Fatigue Life v/s Initial Tensile Strain of Stone Matrix Asphalt Mix with
Cement (1%) as filler
Table 4.17 Indirect Tensile Fatigue Test on Stone Matrix Asphalt Mix with Lime
(2%) as filler at 25oC
96
Initial
Height Resilient Fatigue
Stres Tensile Resilient Tensile
Load, of Horizontal Life, No.
s Stress, Modulu strain,
N specime Deformatio of
level MPa s, MPa Micro
n, mm n, mm cycles
strain
0.0920
10% 980 66.67 0.02651 343.766 549.182 4998
9
0.0944
10% 980 65.00 0.02884 324.17 597.343 5012
6
0.0932
333.968 573.263 5005
7
0.1857
20% 1960 66.10 0.03803 483.418 787.800 2896
7
0.1860
20% 1960 65.70 0.03685 501.936 763.354 2881
0
0.1858
492.677 775.577 2889
8
0.2728
30% 2940 67.50 0.04698 574.836 973.158 1895
8
0.2833
30% 2940 65.00 0.04563 614.636 945.480 1877
8
0.2781
594.736 959.319 1886
3
0.3683 1060.08
40% 3920
66.67 7 0.05117 712.359 0 1028
0.3711 1115.00
3920
40% 66.10 5 0.05382 683.114 1 1040
0.3697 1087.54
6 697.737 1 1034
97
Object 105
Fig. 4.40 Fatigue Life v/s Stress Level of Stone Matrix Asphalt Mix with Lime (2%)
as
filler
Object 108
Fig. 4.41 Fatigue Life v/s Tensile Stress of Stone Matrix Asphalt Mix with Lime
(2%) as filler
98
Object 110
Fig. 4.42 Fatigue Life v/s Resilient Modulus of Stone Matrix Asphalt Mix with Lime
(2%) as filler
Object 112
Fig. 4.43 Fatigue Life v/s Initial Tensile Strain of Stone Matrix Asphalt Mix with
Lime (2%) as filler
99
Table 4.18 Indirect Tensile Fatigue Test on Stone Matrix Asphalt Mix with Cement
(2%) as filler at 25oC
Initial
Height Resilient Fatigue
Stres Tensile Resilient Tensile
Load, of Horizontal Life, No.
s Stress, Modulu strain,
N specime Deformatio of
level MPa s, MPa Micro
n, mm n, mm cycles
strain
0.0740
10% 790 66.83 0.02526 290.190 523.188 4856
6
0.0748
10% 790 66.16 0.02434 304.213 504.124 4845
1
0.0744
297.202 513.656 4851
3
0.1507
20% 1580 66.50 0.03686 399.635 763.583 2688
4
0.1484
20% 1580 66.67 0.03545 414.522 734.283 2673
8
0.1496
407.079 748.933 2681
1
0.2261
30% 2370 65.67 0.04569 489.716 946.502 1598
1
0.2194
30% 2370 67.66 0.04630 469.033 959.173 1609
6
0.2227
479.375 952.838 1604
8
0.2977 1074.18
40% 3160
66.50 1 0.05185 568.161 0 924
0.2969 1092.56
3160
40% 66.67 5 0.05274 557.180 0 939
0.2973 1083.37
3 562.671 0 932
100
Object 114
Fig. 4.44Fatigue Life v/s Stress Level of Stone Matrix Asphalt Mix with Cement
(2%) as Filler Material
Object 117
Fig. 4.45Fatigue Life v/s Tensile Stress of Stone Matrix Asphalt Mix with Cement
(2%) as filler
101
Object 120
Fig. 4.46 Fatigue Life v/s Resilient Modulus of Stone Matrix Asphalt Mix with
Cement (2%) as filler
Object 122
Fig. 4.47 Fatigue Life v/s Initial Tensile Strain of Stone Matrix Asphalt Mix with
Cement (2%) as filler
Object 124
Fig. 4.48 Fatigue Life v/s Stress Level of Stone Matrix Asphalt Mix with Lime
(1%) and Cement (1%) as fillers
103
Object 127
Fig. 4.49 Fatigue Life v/s Tensile stress of Stone Matrix Asphalt Mix with Lime (1%)
and Cement (1%) as fillers
Object 130
Fig. 4.50 Fatigue Life v/s Resilient Modulus of Stone Matrix Asphalt Mix with Lime
(1%) and Cement (1%) as fillers
104
Object 132
Fig. 4.51 Fatigue Life v/s Initial Tensile Strain of Stone Matrix Asphalt Mix with
Lime (1%) and Cement (1%) as fillers
Table 4.20 Linear Regression Analysis for data obtained from Stone Matrix Asphalt
Mix with filler content 2%
Type of Filler
Relationship R2 value Equations
Materials
Lime Fatigue 0.9493 y = -129.16x + 5932.5
Stress Level
Cement Life 0.9337 y = -128.34x + 5725.5
105
Object 134
Fig. 4.52 Fatigue Life v/s Stress Level of Stone Matrix Asphalt Mix with Lime (2%)
and Cement (2%) as fillers
Object 137
Fig. 4.53 Fatigue Life v/s Tensile stress of Stone Matrix Asphalt Mix with Lime (2%)
and Cement (2%) as fillers
106
Object 140
Fig. 4.54 Fatigue Life v/s Resilient Modulus of Stone Matrix Asphalt Mix with Lime
(2%) and Cement (2%) as fillers
Object 142
Fig. 4.55 Fatigue Life v/s Initial Tensile Strain of Stone Matrix Asphalt Mix with
(2%) and Cement (2%) as fillers
107
CHAPTER 5
DISCUSSIONS AND CONCLUSIONS
5.1 Discussions
5.1.1 Optimum Bitumen Content
1. The Optimum Bitumen Content (OBC) for Stone Matrix Asphalt mix with
Stone Dust, Cement as filler are 5.90% and 5.95% respectively.
2. It is observed that Optimum Bitumen Content for Stone Matrix Asphalt mix
with Stone Dust is found to be 0.84% lower than that of mix with Cement as
filler.
5.1.2 Marshall Stability
1. The Marshall Stability for Stone Matrix Asphalt mix prepared at OBC with
Stone Dust and Cement are 1320kg and 1250kg respectively.
2. It is observed that Marshall Stability for Stone Matrix Asphalt mix prepared at
OBC with Stone Dust as filler is found to be 5.30% greater than that of mix with
Cement as filler.
108
5.1.3 Bulk Density
1. The Bulk density for Stone Matrix Asphalt mix prepared at OBC with Stone
Dust, Cement as filler are 2.362g/cc and 2.372g/cc respectively.
2. It is observed that Bulk density for Stone Matrix Asphalt mix prepared at OBC
with Stone Dust as filler is found to be 0.42% lower than that of mix with
Cement as filler.
5.1.4 Flow
1. The Flow for Stone Matrix Asphalt mix prepared at OBC with Stone Dust,
Cement as filler are 3.0 mm and 3.2 mm respectively.
2. It is observed that Flow for Stone Matrix Asphalt mix prepared at OBC with
Stone Dust as filler is found to be 6.25% lower than that of mix with Cement as
filler.
2. It is observed that Total air voids for Stone Matrix Asphalt mix prepared at
OBC with Stone Dust as filler and Bagasse as stabilizing additive is found to
be 1.58% lower than that of mix with Cement as filler.
5.1.6 Voids in Mineral aggregate (VMA)
1. The VMA for Stone Matrix Asphalt mix prepared at OBC with Stone Dust,
Cement as filler and Bagasse as additive are 17.85% and 18.05% respectively.
2. It is observed that VMA for Stone Matrix Asphalt mix prepared with Stone
Dust as filler and Bagasse as additive is found to be 1.10% lesser than that of
mix with Cement as filler.
5.1.7 Voids Filled with Bitumen (VFB)
1. The VFB for Stone Matrix Asphalt mix prepared at OBC with Stone Dust,
Cement as filler and Bagasse as additive are 74.21% and 74.32% respectively.
109
2. It is observed that VFB for Stone Matrix Asphalt mix prepared at OBC with
Stone Dust as filler and Bagasse as additive is found to be 0.14% greater than
that of mix with Cement as filler.
5.2 Conclusions
1. Marginal increase in Optimum Bitumen Content for Stone Matrix Asphalt mix
with Stone Dust as filler when compared to Cement as filler.
2. Substantial increase in Marshall Stability for Stone Matrix Asphalt mix at OBC
with Stone Dust as filler when compared to Cement as filler.
3. Marginal decrease in Bulk density for Stone Matrix Asphalt mix at OBC with
Stone Dust as filler when compared to Cement as filler.
4. Substantial decrease in Flow value for Stone Matrix Asphalt mix at OBC with
Stone Dust as filler when compared to Cement as filler.
5. Marginal decrease in Total air voids for Stone Matrix Asphalt mix at OBC with
Stone Dust as filler when compared to Cement as filler.
6. Marginal decrease in VMA for Stone Matrix Asphalt mix at OBC with Stone
Dust as filler when compared to Cement as filler.
7. Marginal increase in VFB for Stone Matrix Asphalt mix at OBC with Stone
Dust as when compared to Cement as filler.
110
8. Based on Marshall Properties of Stone Matrix Asphalt mix it is concluded that
Stone Matrix Asphalt mix with Stone Dust as mineral filler are superior than
mix prepared using cement as filler.
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