SuperPave Asphalt Specifications

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SuperPave Asphalt Specifications

• Previous asphalt specifications
• physical property specifications
• penetration
• viscosity
• ductility
• conducted at standard test temperatures
• results used to determine if the material meets
  specification criteria
• tests are empirical in nature
• results are related to pavement performance
  through experience

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SuperPave Asphalt Specifications

• Penetration test
• indicates stiffness of the asphalt
• relationship between stiffness and pavement
  performance has to be gained from experience
• In some tests this relationship may not be very
  good
• Current empirical tests and specifications do not
  give information for the entire range of typical
  pavement temperatures

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SuperPave Asphalt Specifications

• Viscosity test
• fundamental measure of flow
• only provides information about higher
  temperature viscous behavior at the standard test
  temperatures of 60 C and 135 C
• Penetration test
• only describes consistency at a medium
  temperature of 25 C
• lower temperature elastic behavior cannot be
  realistically determined from this data to
  predict low temperature performance

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SuperPave Asphalt Specifications

• Empirical asphalt specifications
• can classify different asphalts with the same
  grading
• in fact these asphalts may have different
  temperature and performance characteristics
• because these asphalts are graded the same one
  might erroneously expect the same characteristics
  during construction and the same performance
  during hot and cold weather conditions

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SuperPave Asphalt Specifications
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SuperPave Asphalt Specifications

• Strategic Highway Research Program SHRP -
  Canadian component C SHRP
• Began research in 1987 into developing a new
  system for specifying asphalt cement and asphalt
  mixes
• asphalt cement specifications are referred to as
  binder specifications
• intended for both modified and unmodified asphalt
  cements

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SuperPave Asphalt Specifications

• Superpave asphalt binder specification
• new test procedures and new equipment
• specified criteria remains constant but the
  temperature at which the criteria must be
  achieved changes for various grades
• tests measure physical properties that can be
  related directly to field performance by
  engineering principles
• tests are conducted at temperatures that are
  encountered by in-service pavements

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SuperPave Asphalt Specifications

• The central theme of the Superpave Binder
  Specification is its reliance on testing asphalt
  binders in conditions that simulate the three
  critical stages during the binders life
• tests performed on the original asphalt represent
  the first stage of transport, storage and
  handling
• the second stage represents the asphalt during
  mix production and construction and is simulated
  by aging the binder in a rolling thin film oven

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SuperPave Asphalt Specifications

• The thin film oven test exposes thin binder films
  to heat and air and approximates the aging of
  asphalt during mixing and construction
• The third stage occurs as the binder ages over a
  long period of time as part of the hot mix
  asphalt pavement layer. This stage is simulated
  for the specification by the pressure aging
  vessel. The procedure exposes binder samples to
  heat and pressure in order to simulate years of
  in-service aging in a pavement

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SuperPave Asphalt Specifications
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SuperPave Asphalt Specifications
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Superpave Asphalt Binder Tests

• Superpave Binder Aging Procedures
• Asphalt binder ages
• volatilization of light oils present in the
  asphalt
• oxidation by reacting with oxygen in the
  environment
• Rolling Thin Film Oven Test (RTFOT)
• simulates both types of aging in the mixing and
  placement of asphalt mix because of the high
  temperatures and air flow involved in the process
• Pressure Aging Vessel (PAV)
• simulates in service aging

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Superpave Asphalt Binder Tests

• Pressure Aging Vessel (PAV)
• simulates in service aging dominated by oxidation
  and not volatilization because of the relative
  moderate in-service temperatures
• binder samples that have been aged in the PAV
  have already been aged in the RTFOT
• Consequently, the PAV residue represents binder
  that has been exposed to all of the environmental
  conditions to which binders are subjected to
  during production and service

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Superpave Asphalt Binder Tests

• Rolling Thin Film Oven Test (RTFOT)
• AASHTO T240 ASTM D 2872
• provides aged asphalt binder that can be used for
  further testing of physical properties
• determines the mass quantity of volatile lost
  during the process
• indication of the aging that may occur in the
  asphalt during mixing and construction operations
• specified as 1 maximum

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SuperPave Asphalt Specifications
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Superpave Asphalt Binder Tests

• Pressure Aging Vessel (PAV)
• AASHTO PP1
• simulates the effects of long term in-service
  aging of asphalt
• Uses binder that has previously been aged in the
  RTFOT since asphalt that is exposed to long term
  aging has also been through the mixing and
  construction process
• exposes the binder to high pressure and
  temperature for 20 hours

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SuperPave Asphalt Specifications
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SuperPave Asphalt Specifications
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Superpave Asphalt Binder Tests

• Dynamic Shear Rheometer (DSR)
• AASHTO TP5
• Asphalt Behavior depends on both loading time and
  temperature and this test evaluates both effects
• measures rheological properties
• complex shear modulus
• phase angle
• intermediate to high temperatures
• original binder RTFOT PAV residues

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Superpave Asphalt Binder Tests

• Dynamic Shear Rheometer (DSR)
• used to characterize both elastic and viscous
  behavior
• G (G star) complex shear modulus
• measures the total resistance of the asphalt to
  deformation
• elastic component (recoverable deformation)
• viscous component (non-recoverable deformation)
• ? (delta)
• indicates the relative amounts of recoverable and
  non-recoverable deformation

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SuperPave Asphalt Specifications
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Superpave Asphalt Binder Tests

• Values of G and ? for asphalts are highly
  dependant on temperature and frequency of loading
• High temperatures
• behavior is viscous with no capacity for
  recovering or rebounding
• ? 90
• Low temperatures
• behavior is elastic witch rebounds from
  deformation
• ? 0

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SuperPave Asphalt Specifications
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SuperPave Asphalt Specifications
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SuperPave Asphalt Specifications
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Superpave Asphalt Binder Tests

• Superpave asphalt binder specification
• Dynamic Shear Rheometer (DSR)
• Permanent Deformation
• G/sin ? at test temperature gt 1.00 kPa original
  binder
• G/sin ? at test temperature gt 2.20 kPa RTFOT
  binder
• Fatigue Cracking
• G (sin ?) at test temperature lt 5000 kPa PAV
  binder

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Superpave Asphalt Binder Tests

• Rotational Viscometer
• ASTM D4402
• used to determine the flow characteristics of the
  asphalt binder
• ensure that the asphalt is fluid enough to be
  pumped and handled at the hot mix facility
• measured on the original asphalt binder
• test temperature at 135 C
• maximum viscosity 3 Pa s

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Superpave Asphalt Binder Tests

• Bending Beam Rheometer (BBR)
• AASHTO TP1
• measures low temperature properties of asphalt
  that are too stiff to be measured by the DSR
• BBR (stiffness) used in conjunction with the
  Direct Tension Test (strength and stretching
  ability before breaking)
• BBR measures deflection or creep under a constant
  load and temperature

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Superpave Asphalt Binder Tests

• Bending Beam Rheometer (BBR)
• test temperatures are related to a pavements
  lowest service temperature when the asphalt
  binder acts more like an elastic solid
• PAV asphalt binder
• test measures the performance characteristics of
  binders as if they had been exposed to hot mixing
  and some in-service aging

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SuperPave Asphalt Specifications
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Superpave Asphalt Binder Tests

• Bending Beam Rheometer (BBR)
• applying a constant load (980mN) to the center of
  the asphalt beam and measuring the deflection
  during the 4 minute test creep stiffness (S) and
  creep rate (m) can be calculated
• creep load simulates thermal stresses that
  gradually build up in a pavement when temperature
  drops
• Creep Stiffness (S) resistance of the binder to
  creep loading and the m-value is the change in
  asphalt stiffness with time during loading

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SuperPave Asphalt Specifications
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SuperPave Asphalt Specifications
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Superpave Asphalt Binder Tests

• Bending Beam Rheometer (BBR)
• Low temperature cracking
• Creep Stiffness (S) _at_ 60s lt 300 Mpa
• S is between 300 to 600 Mpa the Direct Tension
  test may be used in lieu of the creep stiffness
  requirement
• m value (m) _at_ 60s gt .3

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Superpave Asphalt Binder Tests

• Direct Tension Tester
• AASHTO TP3
• strong relationship between stiffness of asphalt
  binders and the amount of stretching they undergo
  before breaking
• asphalts that undergo considerable stretching
  before failure are called ductile
• those that break without much stretching are
  called brittle
• it is important that asphalts be capable of a
  minimal amount of elongation

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Superpave Asphalt Binder Tests

• Direct Tension Tester
• typically stiffer asphalts are more brittle and
  softer asphalts more ductile
• creep stiffness as measured by the BBR is not
  adequate enough to completely characterize the
  capacity of asphalts to stretch before breaking
• some asphalts exhibit high creep stiffness but
  can also stretch farther before breaking
• therefore SHRP specifications recognize these
  stiff but ductile binders

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Superpave Asphalt Binder Tests

• Direct Tension Tester
• these asphalts are allowed to have high creep
  stiffness (300 to 600 Mpa) if they can also
  display reasonable ductile behavior at low
  temperatures
• if creep stiffness lt 300 Mpa the direct tension
  test is not required
• PAV asphalt binder
• test measures the performance characteristics of
  binders as if they had been exposed to hot mixing
  and some in-service aging

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SuperPave Asphalt Specifications
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SuperPave Asphalt Specifications
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SuperPave Binder Specifications

• Intended to improve performance by limiting the
  potential for asphalt to contribute towards
• permanent deformation
• low temperature cracking
• fatigue cracking
• required physical specifications remain constant
  for all performance grades (PG)
• the temperatures at which these properties must
  be reached vary depending on the climate in which
  the binder is expected to be used

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SuperPave Asphalt Specifications
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Performance Grades M320 (MP1)
CEC
Avg 7-day Max, oC
PG 46 PG 52
PG 58 PG 64 PG
70 PG 76 PG 82
1-day Min, oC
-34 -40 -46 -10 -16 -22 -28 -34 -40
-46 -16 -22 -28 -34 -40 -10 -16 -22
-28 -34 -40 -10 -16 -22 -28 -34 -40
-10 -16 -22 -28 -34 -10 -16 -22 -28
-34
ORIGINAL
gt 230 oC
(Flash Point) FP
lt 3 Pa.s _at_ 135 oC
(Rotational Viscosity) RV
(Dynamic Shear Rheometer) DSR G/sin ?
gt 1.00 kPa
46 52
58 64
70 76
82
(ROLLING THIN FILM OVEN) RTFO Mass Loss lt
1.00
(Dynamic Shear Rheometer) DSR G/sin ?
gt 2.20 kPa
46 52
58 64
70 76
82
(PRESSURE AGING VESSEL) PAV
20 Hours, 2.07 MPa
90 90 100
100 100 (110)
100 (110) 110 (110)
(Dynamic Shear Rheometer) DSR G sin ?
lt 5000 kPa
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10 7 4 25 22 19 16 13
10 7 25 22 19 16 13 31
28 25 22 19 16 34 31 28 25
22 19 37 34 31 28 25 40
37 34 31
( Bending Beam Rheometer) BBR S Stiffness
m- value
S lt 300 MPa
m gt 0.300
-24 -30 -36 0 -6 -12 -18 -24 -30
-36 -6 -12 -18 -24 -30 0 -6
-12 -18 -24 -30 0 -6 -12 -18
-24 -30 0 -6 -12 -18 -24 0
-6 -12 -18 -24
(Bending Beam Rheometer) BBR Physical
Hardening
Report Value
gt 1.00
(Direct Tension) DT
-24 -30 -36 0 -6 -12 -18 -24 -30
-36 -6 -12 -18 -24 -30 0 -6
-12 -18 -24 -30 0 -6 -12 -18 -24
-30 0 -6 -12 -18 -24 0 -6
-12 -18 -24
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