Upload
horace-prophetic-davis
View
248
Download
4
Embed Size (px)
Citation preview
8/14/2019 FINAL Asphalt Mix Design.doc
1/33
ACKNOWLEDGEMENT
Without the help of certain individual this project would have
completed. First and foremost we would like to thank God for giving us
the strength to do this project. Secondly we would like to thank Mrs. E.
Burrowes the construction a! "echnician and Mr. G. #oomes the
construction a! "echnician$ who displayed unwavering patience and
understanding when assisting us to carry out the various la!oratory
tests% she was always approacha!le even though sometimes our
&uestions were repeatedly asked. We are especially grateful for her
kind words of encouragement when we were in despair.
We would also like to thank Mr. ' (ryee$ for her input as our tutor and
for providing us with the fundamental start that was needed to do this
project.
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 1
8/14/2019 FINAL Asphalt Mix Design.doc
2/33
OBJECTIVE
"he main purpose of this project is to create a suita!le (sphalt Mi)
*esign which fulfills all the necessary properties of fle)i!ility$
dura!ility$ and worka!ility$ without sacrificing resistance to permanent
deformation.
THEORY
+avements are !uilt,up surfaces which provide a smooth surface for
the safe passage of vehicle under any weather condition and also
distri!ute vehicular loads to the underlying su! grade. "here are two
types of pavements-
Flexible Pavemen!
Ri"i# Pavemen!
n Fle)i!le +avements loads are transmitted downward from one layer
to the other% from the !ase layer$ to the su! !ase layer and finally to
the su! grade. "he Base layer is located immediately !elow the
wearing surface of the pavement and its main function is to increase
stiffness$ reduce fatigue$ distri!ute loads through the given thickness
of the pavement and provide drainage for the pavement. /ne factor
which plays a very integral role in the a!ility of the !ase layer to
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 2
8/14/2019 FINAL Asphalt Mix Design.doc
3/33
distri!ute load is the /ptimum moisture content. /ptimum moisture
content$ in short$ represents the amount of water content which will
produce the ma)imum material density. /ptimum moisture content is
usually plotted against density of material on a graph. "he density of
the material at the /ptimum moisture content is known as the
Ma)imum *ry *ensity.
"he Su! !ase layer is located !etween the Base layer and the Su!
grade layer. "he Su! !ase layer serves as a su!stitute for the su!
grade layer$ in terms of strength$ where the su! grade is e)tremely
weak. "he su! !ase also provides resistance to capillary action and
prevents frost action in the pavement. "he design of the su! !ase may
!e affected !y the mount of traffic e)pected$ position of water ta!le
and also the type of soil within the su! grade and its condition.
"he su! grade represents the natural ground on which the entire
pavement rests. ts function is to provide the necessary !earing
capacity for the load that is transferred to it !y the pavement. "he
performance of the pavement is directly related to the strength of the
su! grade. Factors affecting its performance include% density$ moisture
content$ eases of compaction$ permanency of compaction and
drainage. "he su! grade can !e strengthened !y soil sta!ili0ation$
water pumping and the implementation of good drainage systems.
n #igid +avements$ loads are transmitted directly to the su! grade
layer. #igid +avements are usually constructed using +ortland cement
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 3
8/14/2019 FINAL Asphalt Mix Design.doc
4/33
concrete due to the high modulus of elasticity and rigidity the
pavement. "he !asic type of concrete pavement consists of a mi)ture
of coarse aggregate$ fine aggregate$ +ortland cement$ water and
admi)tures. "hey are mostly used for highways su!jected to severe
service conditions such as ur!an highways$ rural highways and
runways.
+avements are classified according to the type of surfacing materials
used. "he Bituminous surface treatment and +ortland cement concrete
surface treatment$ !ut for this project emphasis will !e placed on the
!ituminous surfacing materials.
Bitumen can !e descri!ed as a !lack sticky or viscous su!stance used
as an adhesive or water proof on !uildings and road construction. t
consists of hydro car!on and three derivatives which are solu!le in
car!on dio sulphate and are soften gradually when heated. "he
hydrocar!ons that make up !itumen can generally !e made up of the
following-
(sphaltenes
#esins
/ils
A!$%alene!are large$ high,molecular,weight hydrocar!on fractions
precipitated from asphalt !y a designated paraffinic naphtha solvent at
a specified solvent,asphalt ratio. (sphaltenes have a car!on,to,
hydrogen ratio of 1.2. (sphaltenes constitute the !ody of the asphalt.
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 4
8/14/2019 FINAL Asphalt Mix Design.doc
5/33
#esins are hydrocar!on molecules with a car!on,to,hydrogen ratio of
more than 1.3 !ut less than 1.2. #esins affect the adhesiveness and
ductility properties of asphalt. /ils are hydrocar!on molecules with a
car!on,to,hydrogen ratio of less than 1.3. /ils influence the viscosity
and flow of the asphalt.
"he term 4!ituminous !inder5 includes 4coal tar5$ 4natural asphalt5 and
!itumen o!tained from petroleum crude 6petroleum !itumen7. "ars
with suita!le properties are now not widely availa!le. t is o!tained !y
refinery processes from petroleum. Bitumen can also !e found in
natural deposits or as a component of naturally occurring 6native7
asphalt which is associated with mineral matter.
8ative asphalt occurs when petroleum rises to the earth5s curst and
the volatile oils are evaporated. "hese native asphalts were found in
pools and asphalt lakes. /ne of the more well,known deposits of native
asphalts is the 9"rinidad ake: deposit on the island of "rinidad off the
north coast of South (merica. Before the development of the
processes for producing asphalt cement from crude petroleum
products$ native asphalts were the only sources of supply for early
pavement projects. "he first asphalted pavement was !uilt in ;23< in
ondon$ England. ( year later construction of road and street
pavements !egan in the =nited States in 8ewark$ 8ew 'ersey.
With the invention of the automo!ile$ which re&uired smooth all,
weather pavements$ the demand for asphaltic pavements grew. "hus$
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 5
8/14/2019 FINAL Asphalt Mix Design.doc
6/33
the process for producing asphalt cement from crude petroleum
products grew$ which led to the development of modern asphalt
cement.
(sphalt cement is a valua!le !y,product o!tained when petroleum5s
are processed to o!tain gasoline$ kerosene$ fuel oil 6diesel and
lu!ricating7 and other asphalt products. "here are three types of
petroleum found in the earth5s crust-
A!$%ali&'ba!e &()#e *il!
Pa(a++in'ba!e &()#e *il!
Mixe#'ba!e &()#e *il!,
(sphaltic,!ase crude oils are used to derive A!$%al &emen !y a
straight,run distillation process. (sphalt cement may also !e o!tained
from mi)ed,!ase crude oils !ut the process is very complicated.
Bituminous products may !e o!tained form paraffin,!ase crude oils !y
a destructive distillation process involving chemical changes. "hese
!ituminous materials should not !e classified as asphalt.
(sphaltic concrete is made up of mi)ture of coarse aggregate$ fine
aggregate$ mineral filler and !itumen$ well proportioned in order to
minimi0e cost !y producing the most suita!le asphaltic concrete yields
a pavement that is sta!le$ dura!le$ fle)i!le and skid resistant. t is not
always possi!le to optimi0e all four properties% thus$ compromises are
often made.
+avements have certain properties-
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 6
8/14/2019 FINAL Asphalt Mix Design.doc
7/33
8/14/2019 FINAL Asphalt Mix Design.doc
8/33
$*li!%in". Pavemen blee#in"occurs when too few voids are left in
the mi) and traffic loads compact the pavement on a hot day$ forcing
asphalt to the surface of the roadway. "his action covers the e)posed
rough aggregate and the pavement !ecomes slippery. With voids in
pavements as low as @ or ; percent$ slippery pavements will not
occur$ however$ most specifications re&uire A or percent air voids to
prevent surface !leeding.
A""(e"ae $*li!%in" results after a pavement receives continuous
wear form traffic and the surface aggregates polish$ forming a slippery
pavement. +olishing can !e reduced !y using relatively hard
aggregates.
(s mentioned earlier it is very hard achieve all properties$ hence
sacrifices have to !e made. E)ample$ !y ma)imi0ing dura!ility$ !oth
sta!ility and skid resistance are compromised. Sta!ility is
compromised when thick coatings of asphalt are placed over the
aggregates and causes the !onding !etween aggregates and asphalt
cement to lessen 6as the aggregates tend to float in the asphalt7. Skid
resistance is compromised as a)le loads tend to compact a pavement
which has more asphalt than needed to cover the aggregates$ causing
!leeding of the asphalt and there!y creating a slippery surface.
"his project however will emphasi0e on (sphalt mi) *esign and not
road construction.
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 8
8/14/2019 FINAL Asphalt Mix Design.doc
9/33
"he design of hot mi)es are mainly a matter of selecting and
proportioning ingredients to o!tain the desired finished construction
properties i.e. the proper si0e and gradation of coarse and fine
aggregates$ filler and the !itumen grade. "he aim is to find an
economical !lend and gradation of aggregates and asphalt 6within the
specification limits7 that yields a mi) to have-
Enough asphalt to ensure a dura!le$ compacted pavement !y
thoroughly coating$ !onding and waterproofing the aggregate.
Enough mi) sta!ility to satisfy the demands of traffic without
distortion or displacement.
Coids in the total compacted mi) sufficient that will permit a
slight amount of added compaction under traffic loading without
!leeding or loss of sta!ility. >owever$ the volume of voids should
!e at a minimum to keep out harmful air and moisture content.
Enough worka!ility to allow placement and proper compaction of
the paving mi) without any segregation.
"here are four essential specifications which give an indication
of the mi) properties- "he voids in mineral aggregates 6CM(7$ (ir
voids$ Marshall Sta!ility and Flow.
"he Marshall Sta!ility and flow are determined from the
e)periment. *uring the mi)ing procedures asphalt mi) is
compacted in a cylindrical mould and cured under re&uired
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 9
8/14/2019 FINAL Asphalt Mix Design.doc
10/33
conditions. "he resulting !ri&uette is then loaded and its strength
to failure 6sta!ility7 and its deformation 6flow7 are measured.
"he voids in mineral aggregate 6CM(7 ensures that the aggregate
grading is not too dense. (ggregate grading which is too dense
will prevent ade&uate coating of the particles which is essential
for the sta!ility and dura!ility of the mi). Within the CM($ there
has to !e air voids which will allow for some compaction of the
pavement$ without forcing asphalt to the surface$ creating
pro!lems such as !leeding and low skid resistance.
(fter the aggregates meeting the specifications have !een
selected$ the optimum asphalt cement content is determined.
(sphalt cement is the most e)pensive constituent of the mi)ed%
therefore its conservation will !e very economical.
"he optimum asphalt cement is usually found through varying the
asphalt cement contents !y increments of 1.D$ 6!y weight7
typically commencing at .1 through to a ma)imum of ;1. t is
not normally necessary to take more than five 6D7 different
asphalt cement contents. "rial mi)es are then done at these
selected ( contents and the following parameters are measured-
o Marshall Sta!ility$
o Flow$
o Bulk density of compacted !ri&uettes$
o Ma)imum #elative density$
o (ir voids
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 10
8/14/2019 FINAL Asphalt Mix Design.doc
11/33
o Coids in Mineral (ggregates 6CM(7.
"he results of the parameters are then plotted against the (
contents and the optimum ( content selected !ased on the
following specified criteria-
o "he Medium air voids$
o "he ma)imum !ulk relative density of !ri&uettes
o "he ma)imum sta!ility.
"he average ( content is then used to check for compliance with
the si) specifications to ensure that they are met !efore making a
decision to accept this average as the optimum asphalt cement
content.
THE -TANDARD PENETRATION TE-T
AIM0
"o determine the penetration of semi,solid and solid !ituminousmaterial
APPARATUS
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 11
8/14/2019 FINAL Asphalt Mix Design.doc
12/33
+enetration (pparatus
+enetration needles
Sample container 6metal7
"hermometer
Water !ath
"ransfer dish 6D11 ml7
"imer
THEORY
"he penetration test is used as a measure of consistency$ !y
measuring at a fi)ed temperature. >igher values of penetration
indicate softer consistency. "he sample is melted and cooled under
controlled conditions. "he penetration is measured with a penetometer
!y means of which a standard needle is applied to the sample under
specific conditions.
( needle of standardi0ed dimensions is allowed to penetrate into a
sample of the !itumen under normal conditions at temperature of
A2o$ under a load of ;11g$ for a time of D seconds. "he amount of
indentation$ in units of 1.;mm$ is termed the 4penetration5.
FLA-H POINT TE-T
AIM:
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 12
8/14/2019 FINAL Asphalt Mix Design.doc
13/33
"o determine the flash point of asphalt or !itumen$ using of the
leveland /pen up apparatus.
APPARATUS
leveland /pen up (pparatus
Bunsen flame with +G supply
"hermometer
THEORY
"he flash point test is done to determine the temperature at which the
asphalt will ignite. Bitumen with a low flash point usually indicates
contamination !y other fuel oils of lower !oiling point. =sing asphalt
with a flash point at road pavement temperatures will result in a road
surface that will easily ignite under pavement conditions. (lso$ the
flash point test is done to ensure safety in the la!$ since the asphalt
will !e handled at high temperatures. f the temperature at which the
asphalt is !eing handled e)ceeds the flash point$ the asphalt !ecomes
a potential ha0ard for !urns and for poisoning !y way of the inhalation
of no)ious su!stances.
/ther tests that give characteri0ation of !ituminous materials are- ,
Specific Gravity$ *uctility$ Float "est$ Stiffness Modulus$ Sampling
Bituminous Materials$ Fraass !reaking +oint and Ciscosity. a!oratory
tests include the 4loss on heating test5 and the 4rolling thin film oven
test5. 8o detailed consideration of these other tests is given in this
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 13
8/14/2019 FINAL Asphalt Mix Design.doc
14/33
report. Suffice it to say that these tests$ if carried out$ must !e
referenced to an appropriate standard$ the latest version of which
must always !e fully complied with. (lso$ it is assumed that there is
familiarity with the tests for suita!ility and properties of aggregates.
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 14
8/14/2019 FINAL Asphalt Mix Design.doc
15/33
SOFTENING POINT TEST
"he second method of defining hardness or consistency is to determine
the temperature at which a fi)ed consistency occurs. "he test is
carried out !y recording the temperature$ at which the !itumen softens
sufficiently to allow a steel !all$ placed on a sample of the !itumen$ to
fall a fi)ed distance$ when the temperature is raised at a specified rate.
8o change in the physical state of the !itumen occurs and the
softening point must not !e treated as the melting point. Softening
points can vary from ADo to ;A1o.
APPARATUS
Bunsen flame with +G supply
"hermometer
Shield
Glass container
#ing apparatus
Water !ath
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 15
8/14/2019 FINAL Asphalt Mix Design.doc
16/33
THE MAR-HALL TE-T
AIM0
"o measure the resistance to plastic flow of cylindrical specimens
6!ri&uettes7 of !ituminous paving mi)tures loaded on the lateral
surface !y means of the Marshall apparatus. "he !ulk relative density
of the compacted Marshall !ri&uettes will also !e measured.
THEORY
"he Ma(!%all Mix #e!i"nprocedure is pro!a!ly the most widely used
method of !ituminous mi) design. t is governed !y (S"M ;DDolder
oading 'ack
>ot +late or oven
ompaction >ammer
"rowel
>eat #esistant Gloves
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 17
8/14/2019 FINAL Asphalt Mix Design.doc
18/33
"hermometers
Balance
>ot Water Bath
Flow Meter
Filter *iscs
Scoop
Small metal containers
Specimen mould holder
Breaking head
MATERIAL
Blen#e# &*a(!e a""(e"ae
Fine A""(e"ae
Fille(
Bi)men
PROCED1RE0
;. (ggregates were first sieved and weighed out to attain the
re&uire variations in si0e for the mi).
A. (ggregates$ filler and the mold were then placed in the oven
and left to dry for 23 %*)(!at 456*C * 445*C,
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 18
8/14/2019 FINAL Asphalt Mix Design.doc
19/33
. (ll essential mi)ing e&uipment that would come in contact
with either the asphalt cement$ ($ or the su!se&uent
asphaltic concrete mi) was placed on the hot plate and
!rought to a operating temperature *+ 78*& * 437*C.
. =sing a pre,determined ( content of .D$ the Mass of (
needed was calculated.
D. "he aggregates were then removed from the oven and place
within a mi)ing !owl and dry mi)ed thoroughly. (fter the
aggregates were thoroughly mi)ed$ they were placed on the
!alance and the pre,determined &uantity of !itumen was
poured 6as descri!ed in step D7.
3. "he mi)ing !owl was transferred to the hotplate and the dry
mi)? !itumen was !lended$ avoiding spillage$ until aggregate
thoroughly coated with !itumen.
H 8ote Steps I J must !e e)ecuted &uickly$ accurately and cautiously
to minimi0e heat loss and avoid injury at all cost !y wearing the right
protective apparel.
J. "he mold was taken from the oven and placed on the
compaction pedestal 6a filter paper disc was placed in the
!ottom of the mold7 and the !lend transferred into it. (fter
the entire !atch was placed in the mold it was spaded
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 19
8/14/2019 FINAL Asphalt Mix Design.doc
20/33
vigorously with a heated knife$ ;D times around the perimeter
and ;1 times over the interior.
2. "he !lended components were pored unto a filter paper disc
placed within the compacted mold$ and with the compaction
hammer held as near to vertical as possi!le$ D1 !lows were
applied to the top of thespecimen.
8/14/2019 FINAL Asphalt Mix Design.doc
21/33
the specimen. "he reading was then recorded and the
!ri&uette sent to disposal.
RE-1LT- AND CALC1LATION0
Ma!! *+ a""(e"ae )!e# * *baine# Ma(!%all B(i9)ee:
Prepare by: T. Smith, S. Ashman and C. Francis Asphalt mix design project 21
8/14/2019 FINAL Asphalt Mix Design.doc
22/33
;Table 4,5eight 6mm7 33.J1 3D.11 3D.A1 3D.11 (verage K3D.D1
;, Mass of asphalt cement to produce ( content of D.D
( content D.D K Mass of ( ) ;11 Mass of ( L"otal mass of aggregate
( content D.D K Mass of ( ) ;11 Mass of ( L ;;
8/14/2019 FINAL Asphalt Mix Design.doc
23/33
;Table 4,4