asphalt binders used in mongolia in the view of superpave specification,july 27, 2012

Asphalt Binders Used in Mongolia in the view of Superpave Specification

Bituminous Material ChairSchulich School of Engineering

University of CalgaryCanada

July 2012

Empirical Asphalt Specifications- penetration, softening point, ductility…

- tests empirical in nature

- results are related to pavement performance through

experience

SuperPave Asphalt Specification- 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

SuperPave Binder Specification

- the temperatures at which these properties must be

reached vary depending on the climate in which the binder

is expected to be used

- tests asphalt in conditions that simulate the three critical

stages during the binders life

• tests performed on the original asphalt:

- transport, storage, handling

• tests performed on asphalt after changes during

construction simulated by RTFOT

• tests performed after long service life simulated by

PAV

SuperPave Binder Specification

SuperPave Asphalt Binder Test

• Rolling Thin Film Oven Test (RTFOT)

Simulates changes in asphalt binder during mix preparation

and pavement construction


• Pressure Aging Vessel (PAV)

Simulates the effects of long term in-service aging of

asphalt

Sample rack and pan

Loaded Pressure aging vessel (PAV)


• Dynamic Shear Rheometer (DSR)

- Asphalt behaviour depends on both loading time and

temperature and this test evaluates both effects

-measures rheological properties

• complex shear modulus (G*)

• phase angle (δ)

- intermediate to high temperatures

- original binder RTFOT & PAV residues


• Dynamic Shear Rheometer (DSR)

DSR animation

Geometries for DSR (8 and 25 mm)


• Rotational Viscometer

- ensures that the asphalt is fluid

enough to be pumped and

handled at the hot mix facility

- measured on the original

asphalt binder


• Bending Beam Rheometer

- measures low temperature properties of asphalt

- measures deflection (creep) under a constant load and

temperature

- test temperatures are related to a pavement lowest

service temperature

- tests asphalt after PAV (exposed to hot mixing and in-

service aging)


• Bending Beam Rheometer

Principle of BBR

BBR molds


• Direct Tension Tester

- strong relationship between stiffness

of asphalt binders and the amount of

stretching they undergo before breaking

- important that asphalts be capable of

a minimal amount of elongation

- some asphalts exhibit high creep stiffness but can also

stretch farther before breaking

• 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 < 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


Performance Grades M320 Table

ENCI 579 6 17

PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82

(Rotational Viscosity) RV

100 (110)90 90 100 100 100 (110) 100 (110) 100 (110)

(Flash Point) FP

46 52 58 64 70 76 82

46 52 58 64 70 76 82

(ROLLING THIN FILM OVEN) RTFO Mass Loss < 1.00 %

(Direct Tension) DT

(Bending Beam Rheometer) BBR Physical Hardening

28

-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

Avg 7-day Max, oC

1-day Min, oC

(PRESSURE AGING VESSEL) PAV

ORIGINAL

> 1.00 kPa

< 5000 kPa

> 2.20 kPa

S < 300 MPa m > 0.300

Report Value

> 1.00 %

20 Hours, 2.07 MPa

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

(Dynamic Shear Rheometer) DSR G* sin

( Bending Beam Rheometer) BBR “S” Stiffness & “m”- value

-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

-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

(Dynamic Shear Rheometer) DSR G*/sin

(Dynamic Shear Rheometer) DSR G*/sin

< 3 Pa.s @ 135oC

> 230 oC

CEC

PG Specification AASHTO M320 Table 3

Multiple Stress Creep Recovery (MSCR)

• Multiple Stress Creep Recovery Test of an Asphalt

Binder Using a Dynamic Shear Rheometer (MSCR)

– measures the ability of a binder to maintain an elastic

response at two different stress levels while being

subjected to ten cycles of stress and recovery

– percent recovery in the high stress level can be used

to measure elastic properties as non recoverable

creep compliance Jnr



• Standard “S” Grade, in most typical situations, will be for

traffic levels of less than 10 million equivalent single axle

loads (ESALs).

• High “H” Grade, in most situations, will be for traffic

levels of 10 to 30 million ESALs.

• Very High “V” Grade, in most situations, will be for traffic

levels of greater than 30 million ESALs.

Table 1 Table 2 Table 3Sample Id.

Lab Number

Date

Original Binder Properties

Viscosity @ 135°C [Maximum 3000 mPa.s] [mPa.s]

Flash Point [Minimum 230°C] [°C]

Dynamic Shear [G*/sin d] [min 1.0 kPa] [kPa]

Temp [°C]

Pass / Fail Temp [°C]

Properties after RTFOT

RTFOT Mass Loss [%]

Standard Traffic "S" Grade

J nr3.2 , max 4.0 kPa-1

Heavy Traffic "H" Grade

J nr3.2 , max 2.0 kPa-1

Very Heavy Traffic "V" Grade

J nr3.2 , max 1.0 kPa-1

J nrdiff , max 75%

Test temperature, °C

Properties after PAV

PAV Aging Temperature [°C]

"S" Grade

Dynamic Shear [G* sin d] [max 5000 kPa] [kPa]

"H & V" Grades

Dynamic Shear [G* sin d] [max 6000 kPa] [kPa]

Temp [°C]

DSR Pass / Fail Temp [°C]

Creep stif fness [S-max. 300 MPa] @ 60s

m-value [min. 0.300] @ 60 s

Temperature, [°C]

Failure Strain, [Min. 1.0%] [%]

Performance Grade

Superpave PG Grade

True Superpave Grade

True Superpave Grade by MSCR

T

Composition

Application of Performance Graded Asphalt Specification in Road

Construction

PGAC Selection Process

PGAC Selection Process

Weather Database

PAVEMENT DESIGN TEMPERATURES -> (HT, LT)

Grade Selection Matrix

“ENVIRONMENTAL”GRADE -> PG HT-LT

Grade Bumping Protocol(HT Only)

“DESIGN”GRADE -> PG HT-LT

Practical Design Considerations

Special Design Considerations

1. Pavement Design Temperatures2. PGAC Environmental Grade3. PGAC “Design” Grade

PG HT-LT

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Specify Site

Reliability, HT Reliability, LTDepth (mm)

Select Model

Pavement Temperature Models

Air Temperatures

•Availability•Storage & Handling•Cost vs, Reliability

1

2

3

A

B

STEP

STEP

STEP

Considera

tion

Considera

tion

Determining Pavement Design Temperatures

– the hottest seven-day period was identified and the average maximum air temperature (for this seven-day period) was computed and used to define the hot temperature design condition, and

– the one-day minimum air temperature was used to define the cold temperature design condition

• Specifying Reliability – Explicitly Considering Risk

– Reliability is defined as the percent probability, in a single year, that the actual temperature (one day low or high temperature) will not exceed the design temperature


• Specifying Reliability – Considering Risk

– Level of reliability is a function of the application

• Is this a major highway or low volume road?

• Is this a runway or taxiway/apron?

• What is the implication of a failure?

– Reliability from the high temperature grade can be different for the low temperature grade

– Consider a high level of reliability (99%) on the high temperature

• Rutting leading to safety issues i.e. Hydroplaning


• Specifying Reliability – Explicitly Considering Risk

– Consider support for a moderate level (90%) for low pavement temperature (overlays)

• Failure modes like cracking are a performance cost/ issue and therefore must be set within the context of life cycle cost considerations.

PGAC Calgary, Alberta

Environmental Grade PG 58-31

PGAC Calgary, Alberta

– Environmental Grade PG 58-31

• PG 64-31

– Slow traffic where the average traffic speed

is between 20 to 70 km/hr

– Design ESAL’s over 0.3 million

• PG 70-31

– Standing traffic where the average traffic

speed is less than 20 km/hr

– Design ESAL’s over 0.3 million

Superpave Characterization of Asphalt

Binders for Paving in Mongolia

Superpave Characterization of Asphalt Binders for Paving in Mongolia

Table 1.

Superpave Characterization of Asphalt Binders for Paving in Mongolia

Table 3.

Materials

• Five samples of asphalt binders were provided to our

laboratory

• No data attached, only designation: asphalt binder 1,

2, 3, 4 & 5

Decision

• To test the materials according to Superpave

specification AASHTO M 320 - 09, Table 1 without flash

point (Mongolian laboratories)

• Presently added: AASHTO M 320 - 09, Table 3 (MSCR

– multiple stress and creep recovery test), penetration,

and flash point

• AASHTO M 320-09 Table 2 probably not necessary:

more for polymer modified asphalt binders, not critical

for most of straight run materials

Caveat

• To really judge the quality and potential field

performance of asphalt binder, one needs to have

more information, i.e. the stability of crude oil supply,

chemical/group composition, etc. We have only

SPECIFICATION tests

• Three materials contained water (1, 2 & 5). Samples 1

and 2 contained enough water to prevent

determination of flash point. Other results might be

influenced

Discussion of Test Results

The tested materials can be divided into four “groups”:

• Group 1, asphalt binder No.2 (our designation #5319)

- flash point could not be tested: contained water

- RTFOT mass loss - 2.45% (might partially be

- water)

- high temperature parameter G*/sin ∂ original vs

after RTFOT (61.7 °C to 70.2 °C)

- because of huge hardening after RTFOT, in the

MSCR test (would be grade PG 70-xx) material

scores as suitable for very high traffic

- low temperature parameter -25 °C (suitable for

warmer climates)


The tested materials can be divided into four “groups”:

• Group 1, asphalt binder No.2 (our designation #5319)

- likely presence of lighter oils: possibly added to

bring the material to the same consistency level

as the other materials

- should be rejected and not used for paving

anywhere


• Group 2, asphalt binder No. 5 (our designation #5322)

- contained small amount of water

- very good conventional asphalt binder

- meets the requirements of Superpave PG 58-28

but with 4 °C reserve on the low service

temperature side

- meets our “split” Superpave grade PG 58-31

- ∆ T 92 °C: excellent

- according to MSCR test the material meets the

requirements for use in standard traffic which is

normal for conventional asphalt binders


• Group 3, asphalt binders No. 1, and 3 (our designation

#5318 & #5320)

- asphalt binder No. 1 contained enough water to

prevent determination of flash point

- good to very good conventional asphalt binders

- meet the requirements of the Superpave

PG 58-28

- both materials have ∆ 89 °C: very good

- according to MSCR test both materials meet the



• Discussion of Test Results

• Group 4, asphalt binder No. 4 (our designation #5321)

• - reasonably good asphalt binder suitable for

intermediate to warmer climates

• - meets the requirements for the Superpave grade

• PG 58-22

- ∆ T 84 °C: O.K.

- according to MSCR test the material meets the



• - would not be accepted in Alberta (Canada)

because expected high level of thermal cracking

Ranking of Tested Asphalt Binders

• No.5: very good: anything better only polymer modified

• No.1 & No.3: good performance

• No.4: use in warmer climates

• No.5: do not use

asphalt binders used in mongolia in the view of superpave specification,july 27, 2012

Technology

original asphalt binder

pav asphalt binder test

stiffness of asphalt

high creep stiffness

low temperatures

pavement performance

binders life tests

temperaturetest temperatures