performance testing fundamentals · 2020-07-14 · performance testing fundamentals hassan baaj,...

Performance Testing Fundamentals

Hassan Baaj, Ph.D., P. Eng.NW McLeod Professor in Pavement Materials

Director, Centre for Pavement and Transportation EngineeringDepartment of Civil Engineering, University of Waterloo

Outline

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Ø About CPATT

Ø Introduction – What is “Performance” and why we need “Performance Testing”

Ø Performance Testing Fundamentals

Ø Behaviour of Bituminous Materials

Ø Behaviour Characterization vs. Performance Testing

Ø Performance testing of asphalt mixesØ Low Temperature CrackingØ Rutting Ø FatigueØ Complex (Dynamic Modulus)Ø Flow NumberØ Flow Time

Ø Closing Remarks

CPATT & N.W. McLeod Chair

https://uwaterloo.ca/centre-pavement-transportation-technology/

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4

5


GRINCH Symposium at UW - 2019

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RILEM Symposium at UW -2019

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9

Sustainable Transportation

Pavement Design and

Management

Material Use and Recycling

Traffic Planning

Public TransitAlignments

Land Use and Development

Walkways, Bikeways, &

Parkways

Sustainable pavement is a subset of sustainable transportation

Main focus on Pavement Design and Management; and Material Use and Recycling

CPATT – Key Research Themes

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Sustainable Pavement Engineering and Materialsn Incorporating Sustainability into Pavement Design, Construction,

Maintenance and Managementn Climate Change Impacts on Long Life Infrastructuren Life Cycle Economic Analysis in Public and Private Sector

Infrastructuren Smart Pavement Materials And Structures for the Road of the Future

(Nanomaterials, Self-Healing Materials, Phase-Change Materials, Anti-oxidants, Solar Pavements, Lightweight Aggregates, ..)

n Optimization of the Use of Recycled and Alternative Materials inSustainable Infrastructure Systems

n Advanced Testing Methods and Characterization Techniques ofInfrastructure Construction Materials

CPATT – Key Research Themes

Outline

10

Ø About CPATT






Ø Closing Remarks

Performance?

11

Ø What is Performance?

Credit Photo Eric Weber on Unsplash

1- Merriam-Webster Dictionary2- Cambridge Dictionary

Pavement Performance

12Photo by Evgeni Evgeniev on UnsplashPhoto by Michael Shannon on Unsplash


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Photo by Evgeni Evgeniev on Unsplash

Photo by Diego Jimenez on Unsplash


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Photo by Jeremy Bishop on Unsplash

Photo by Alex Iby on Unsplash

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Tighe, S., K. Huen., and R. Haas. 2007. Environmental and Traffic Deterioration with Mechanistic-Empirical Pavement Design Model. Journal of the Transportation Research Board, No. 1989, Vol.2. Washington, D.C. pp. 336-343.

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Performance TestingWhy do we need performance testing?

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Ø Testing for Mix DesignØ Testing for Pavement DesignØ Testing for Forensic AnalysisØ Testing for Research Ø Testing for Product Development

Why do we need performance testing?

Outline

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Ø About CPATT






Ø Closing Remarks

Performance Testing Fundamentals

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Ø Understand the material: Determining the right testing conditionsØ Sample geometry and sizeØ Loading mode and parametersØ Test Conditions (temperature, frequency, speed of loading, time, etc.)

Ø Why we’re testing? How accurate this should be?Ø Testing for mix designØ Testing for pavement designØ Testing for forensic analysisØ Testing for research Ø Testing for product developmentØ …

Ø What performance: Know what you’re looking for?Ø What is good performance?

Ø Determine performance criteriaØ Compare against standard materialsØ Using the right test for the right property

Ø Do the test results make sense?Ø Repeatability, reproducibility, statistical significance

Ø Make sure your testing equipment and tools are calibrated and in good conditionØ Make sure you’re following the test standards and test protocols

Outline

21

Ø About CPATT






Ø Closing Remarks

Hot Mix Asphalt

AggregatesNatural, manufactured &

recycled

BitumenNeat or modified

EnergyDrying and heating

4 to 7% in mass

40 to 65% of the cost

93 to 96% in mass



Hot Mix Asphalt

Two levels should be considered:Level 1: Materials BehaviourLevel 2: Pavement Structure

Behaviour of bituminous materials

P

A

Force

displacement

P

d

P= k d

Robert Hooke(1653-1703)

Hooke’s Law

Linear Elastic Behaviour

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Linear Elastic Behaviour

Thomas Young(1773-1829)

s = E eYoung’s Modulus

§The spring is used to represent linear elasticity

s s

e 0

E

25

Viscous Behaviour

Newtonian fluid = Linear stress-strain rate relation

ss

s

g

Isaac Newton(1643-1727)

•

g

§The Linear Viscosity is represented by a dashpot

s s

e 0

h

.

•

= ghs s

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Viscous Behaviour

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Visco-Elastic Behaviour

Penetration 155(Very soft)

Penetration 115(Soft)

Penetration 50 (Hard)

After 72 hours

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After 72 hours

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Ø Asphalt cement is sensitive to both Time and Temperature

Ø Studying the behavior of the asphalt requires taking both

factors into account

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Behaviour of bituminous materialsTesting Conditions

Log(N)1 2 3 4

Failure

5

log

-6

-4

-2

6

Linear Visco-Elastic

Non-linear

Influence of temperature

FATIGUE

|e|

1

Permanent deformation(compression loading)

+ coupling T-M

ØImportance of a « good » modelling for road designDi Benedetto (1990)


Strength

Fatigue endurance

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Time lags

t

e

tDynamicModulus

(Stiffness)E*

ComplexModulus s0

e0E* =

s0e0

Phase Angle

j

Concept of Complex Modulus

32

|E*|

j

s

e

t

tE1

E2 COMPLEX Plan : Cole-Cole

The Complex Modulusis a VECTOR

Storage Modulus

Loss Modulus

Linear Viscoelastic Behaviour

Concept of Complex Modulus

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E* = E2 + i. E2

10

100

1000

10000

100000

0.01 0.1 1 10 100

Frequency (Hz)

Co

mp

lex

Mo

du

lus

|E*

| (M

Pa)

Temperatures (°C): -35, -25, -10, 0, 10, 20, 35

Frequencies (Hz): 20, 10, 3, 1, 0.3, 0.1, 0.03, 0.01

Concept of Complex ModulusLinear Viscoelastic Behaviour

Complex Modulus

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1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

Frequency (Hz)

Co

mp

lex

Mo

du

lus

|E*

| (M

Pa)

Reference Temperature (10°C)

Master Curve

Extrapolated zone

Mea

sure

men

tszo

neExtrapolated

zone

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E-

02

1.E-

01

1.E+

00

1.E+

01

1.E+

02

Frequency (Hz)

Dyna

mic

Mod

ulus

|E*|

(MPa

)

-35°C

-25°C

-10°C

0°C

10°C

20°C

35°C

Co

mp

lex

Mo

du

lus

Master Curve

0.01 0.1 1.0 10.0 100


35

0

500

1000

1500

2000

2500

3000

0 5000 10000 15000 20000 25000 30000 35000

E1-Storage Modulus (MPa)

E2-

Los

s M

odul

us (M

Pa)

+30°C+20°C+10°C+0,1°C-10°C-20°C-30°C-35°C-40°C


Master Curve

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Behavior Characterization vs Performance

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http://www.doitpoms.ac.uk/tlplib/optimisation-biomaterials/modulus_strength.php 38

Modulus vs. Strength

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Dynamic Modulus – Performance test?Ø Determine the stiffness of the mix under different loading conditions è

Pavement DesignØ Need a high stiffness at design temperatureØ Allow considering the speed (reflected by the frequency)

Ø Predict the Rutting Resistance Ø Min|E*| at High Temperature

Ø Is this really sufficient?Ø How accurate is the prediction?

Ø Fatigue CrackingØ Max|E*| at Intermediate Temperature

Ø Almost abandoned ideaØ Not supported by studies

Ø Low Temperature CrackingØ Max|E*| at Low Temperature

Ø Very rarely mentioned in the literature!Ø Not supported by studiesØ Not possible with AMPT as the minimum temperature is 4℃

Log(N)1 2 3 4

Failure

5

log

-6

-4

-2

6


Non-linear


FATIGUE

|e|

2Permanent deformation

(compression loading)

+ coupling T-M



Strength

Fatigue endurance

40

41


Log(N)1 2 3 4

Failure

5

log

-6

-4

-2

6


Non-linear


FATIGUE

|e|

3 Permanent deformation(compression loading)

+ coupling T-M



Strength

Fatigue endurance

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Rutting is the permanent deflection in the longitudinaldirection of the pavement.

Rutting (Permanent deformation)

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Surface course

Creep deformation in the bituminous layers

Subgrade

Rutting by excessive creep in the HMA

Surface course

Granular courses« deformation in soil »

Subgrade

Rutting by deformation of granular layers


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LCPC Rutting Test


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LCPC Rutting Test


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LCPC Rutting Test


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Log(N)1 2 3 4

Failure

5

log

-6

-4

-2

6


Non-linear


FATIGUE

|e|

4


+ coupling T-M



Strength

Fatigue endurance

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Fatigue mechanism

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Fatigue cracking

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x

e

contraction

extension

-80

-60

-40

-20

0

20

40

60

80

20 40 60 80 100 120 140 160 180Numéro d'acquisition

Déf

orm

atio

n im

posé

e (m

stra

in)

Loading§ Frequency (Hz)§ time of loading

Amplitudeof strain

eh

eh

Simulationin

the Lab.

Fatigue mechanism

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Three Point Bending

Four Point BendingIndirect Tensile Fatigue Test

Fixed base

Sinusoidal cyclic loading (force or displacement)

Failure section

Asphalt concrete specimen

Two Point Bending

Flexural tests

Fatigue testing approaches

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Fixed base

Asphalt Sample

Loading Actuator

Failure Plan

Fatigue tests – 2-point bending

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Fatigue tests – 4-point bending

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A

B

(A) MAX. CONTRACTION (B) MAX. EXTENSION

Neutral Fibre

How to calculate stress and strain from force and displacement values?

We need to assume a behaviour law

Example (Elastic low)

s = M/I . y

F

D

Fatigue test – Flexural tests

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A

B

At the beginning of the test

s0

s0

+

-

|E*0|

B

A

Neutral Fibre

Advanced stage of the test

sN

sN

+

-

|E*N|

|E*0|

Fatigue test – Flexural tests

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57

H1H2

DH

DH

H1

´ 100% = ep

Fatigue tests – Indirect Tensile Test

0

2

4

6

8

10

12

14

16

18

20

0 20 40 60 80 100 120

Number of cycles (´1000)

Perm

anen

t D

efor

mat

ion

(%)

Failure

0 20 40 60 80 100 120

20

0

4

16

8

12

Fatigue tests – Indirect Tensile Test

58Hartman et al., 2001

l The pressure is the value of the Force(F) distributed on the transversalsection (A)

p = F / Al The normal stress is equivalent to

pressure in homogenous conditions

Pressure = Stress

s = p

StressForce

Homogenous tests

Fatigue tests – Tension Compression

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L L-DL

DL/2

DL/2

l DL is the displacement of the material

l The strain is the percentage of totaldisplacement of the original height

Strain = Relative deformation

e = DL/L

Homogenous tests


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Tension-Compression Fatigue Test


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Tension-Compression test

Destructive Test

Temperatures: 10 °C

Frequency: 10 Hz


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For each tested specimen:Determine the number ofcycles Nf corresponding tofailure.

Log Nf

Log e

Fatigue Line (Wöhler )

|E*|

N

|E*0|

Nf

|E0|2

e6

10+6

Classical fatigue criterion

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Log(N)1 2 3 4

Failure

5

log

-6

-4

-2

6


Non-linear


FATIGUE

|e|5


+ coupling T-M



Strength

Fatigue endurance

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Tensile stresses build-up in the longitudinal direction of the pavement

Low temperature cracking


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66

00.51

1.52

2.53

3.5

0 50 100 150 200 250 300Time (Min)

Con

trai

nte

(MPa

)

-35

-25

-15

-5

50 50 100 150 200 250 300

Ultimate stress

Ultimate Temperature

Hauteur constante

10°C/heure

Tem

péra

ture

(°C

)


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Repeated Load Test – Flow Number

STR

AIN

Flow Number

Ø RuttingØ Min FN at High Temp

TIMEST

RES

S

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70


71


Creep Test – Flow Time

STR

AIN

Flow Time

TIME

STR

ESS

Ø RuttingØ Min FT at High Temp

Outline

73

Ø About CPATT






Ø Closing Remarks

Closing Remarks

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Ø Pavement performance is highly impacted by the performance of the building materials used in the pavement structure

Ø Asphalt concrete is the main material used in a flexible pavement structure and is exposed to traffic loadings, environmental conditions and other damaging factors

Ø The behaviour of asphalt materials is quite complex and asphalt testing requires good knowledge of this behaviour

Ø Testing conditions have significant impact on the quality of the results and the quality of the pavement design and performance prediction

Ø Performance-based mix design would be an excellent tool to improve the quality and the reliability of paving materials and increase the service life of the pavements

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Performance-based design example: French Mix Design ApproachA five level, performance-based designapproach:Level 0 - Determining the minimum bindercontent based on the gradation and richnessfactor.Level 1 - Compaction ability and themoisture sensitivity assessment.Level 2 - Evaluating the rutting resistanceof the mix.Level 3 - Determining the complexmodulus values.Level 4 - Evaluating the fatigue resistanceof asphalt mixes and ε6.

Closing Remarks

performance testing fundamentals · 2020-07-14 · performance testing fundamentals hassan baaj,...

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