ASPHALT MASTER CLASS NOVEMBER 2012 Update ... - Aapaq.org

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ASPHALT MASTER CLASS NOVEMBER 2012 Update ... - Aapaq.org

ASPHALT MASTER CLASS

NOVEMBER 2012

Update - AAPA Project

Asphalt Pavement Solutions – For Life

Development and calibration of a

Long Life Asphalt Pavement design

methodology

Ian Rickards

Consultant, AAPA


Background

• International recognition of long life / perpetual

asphalt pavement performance

• LLAP’s get stronger with time i.e. deflections reduce

• Poor correlation between laboratory / field fatigue

performance i.e. basic design criterion dubious

• Observed LLAP performance explained by:

– Fatigue endurance limit

– Healing

• AAPA project aims to develop, calibrate and

implement a relevant design method


National asphalt characterisation study

Dynamic modulus E*

ASPHALT MATERIALS PERFORMANCE TESTER (AMPT)

SPT TEST - OUTPUT DATA DYNAMIC MODULUS E*

Phase angle δ

Stress

Strain

STRESS & STRAIN

0 90 180 270 360

Phase angle δ = 0 o Elastic

Phase angle δ = 90 o Viscous

SINUSOIDAL LOAD CYCLE (1 CYCLE)


Master curve for asphalt characterisation

These parameters are derived from

laboratory testing, and will be used in

modified CIRCLY software to define

asphalt properties over the spectrum

of pavement temperature and load

speed


Binder characterisation

Complex shear modulus G*

The G* parameter is

shown in literature to

provide a more accurate

prediction of E*


APS-FL Project background and motivation

CORRELATION OF STRAIN DISTRIBUTION AND PERFORMACNE

Percentile

100%

90%

80%

70%

60%

50%

40%

30%

20%

10%

0%

No Fatigue

Fatigue

0 200 400 600 800 1000 1200

N1 2003

N2 2003

N3 2003

N4 2003

N5 2003

N6 2003

N7 2003

N1 2006

N2 2006

N3 2006

N4 2006

N8 2006

N9 2006

N10 2006

S11 2006

S13 2000

Microstrain


APS-FL Project background and motivation

CORRELATION OF STRAIN DISTRIBUTION AND PERFORMACNE

Percentile

100%

90%

80%

70%

60%

50%

40%

30%

20%

10%

0%

No Fatigue

Fatigue

The validation phase of

the AAPA project involves

the analysis of LLAP

sections at NCAT and in

Europe (primarily UK).

0 200 400 600 800 1000 1200

N1 2003

N2 2003

N3 2003

N4 2003

N5 2003

N6 2003

N7 2003

N1 2006

N2 2006

N3 2006

N4 2006

N8 2006

N9 2006

N10 2006

S11 2006

S13 2000

Microstrain


APS-FL Project background and motivation

CURRENT AUSTROADS

DESIGN METHOD

PROPOSED ASP-FL

LLAP DESIGN METHOD

Asphalt Characterisation

Design Modulus

(@wMAPT and traffic speed)

Asphalt Characterisation

Dynamic Modulus (Spectrum

of temperature & traffic speeds)

Select trial asphalt thickness for

analysis

Select trial asphalt thickness for

analysis

Refine

design

thickness

Calculate critical strain using

CIRCLY

Design Traffic

Calculate cumulative strain

distribution using CIRCLY

Refine

design

thickness

Examine performance using

Shell fatigue criterion

Confirm conformance using

LTPP & NCAT field test data


MASTER CLASS 2011

• Proposed methodology subjected to peer review by

local and international expert group post 2011 AAPA

Conference.

• Preliminary endorsement of the APS-FL concepts

• No fundamental flaws identified


MASTER CLASS OUTCOMES


MASTER CLASS OUTCOMES


National asphalt materials characterisation

study

• Study components

– Dynamic modulus E* using AMPT

– Binder complex shear modulus G* using DSR

• Scope of materials:

– Commercial project mixes ex production plant

– 30 mixes in total: 16 x AC14: 14 x AC20

– Binders: C 320; C 450; C 600; A15E; Multigrade


National asphalt materials characterisation

study

• Status – Australian laboratory testing

– Local laboratory asphalt testing complete

• 36 master curves includes repeats

– Local laboratory DSR testing complete for each of

5 bitumen types; includes:

• As delivered bitumen

• Bitumen after RTFO

• Mastic – bitumen plus filler

• Recovered binder


National asphalt materials characterisation

study

• Status – NCAT laboratory correlation study

– Triplicate cylinders of 4 mixes (C 600 to come)

testing complete

– Uncompacted samples of 2 mixes provided –

proceeding

– Anticipate completion end November


RESULTS OF NCAT LAB CORRELATIONS

4 o C

20 o C

35 o C

50 o C


RESULTS OF NCAT LAB CORRELATIONS


RESULTS OF NCAT LAB CORRELATIONS


RESULTS OF NCAT LAB CORRELATIONS


LABORATORY MIX PERFORMANCE CHARACTERISTICS

COMPARED – NIL CONFINEMENT


APS-FL Project background and motivation

CORRELATION OF STRAIN DISTRIBUTION AND PERFORMACNE

Percentile

100%

90%

80%

70%

60%

50%

40%

30%

20%

10%

0%

No Fatigue

Fatigue

The validation phase of

the AAPA project involves

the analysis of LLAP

sections at NCAT and in

Europe (primarily UK).

0 200 400 600 800 1000 1200

N1 2003

N2 2003

N3 2003

N4 2003

N5 2003

N6 2003

N7 2003

N1 2006

N2 2006

N3 2006

N4 2006

N8 2006

N9 2006

N10 2006

S11 2006

S13 2000

Microstrain


Data base

• AAPA acknowledges the work done by Bevan

Sullivan in preparation of an Access data base whilst

ensuring confidentiality of the data sources

• The data base will greatly assist in the data analysis

• On finalisation AAPA anticipate the data base will be

made available to ARWG members and other

researchers to provide a basis for national data

collection


Binders characterisation – preliminary

analysis

• Literature indicates E* is a function of G*

• Higher G* yields higher E*

• Mix E* ranking @ higher temperature

– A15E

– C 320

– C 600

– AR 450 (with 15% RAP)

– Multigrade

• Preliminary binder G* ranking inconsistent


Binders characterisation – preliminary

analysis

• Preliminary observation is that phase angle is

substantially effected by binder type and filler

• Models appear inconsistent based only on G*

• Perhaps improved relationship comparing Gʹ or Gʺ

(PhD topic!)


Data analysis for materials modeling

• Doctoral candidate Saeed Yousefdoost’s project

(supervisor Binh Vuong)

– Calibrate predictive models Witczak and Hirsch using local

mix volumetrics and binder properties

– Review results from the NCAT lab testing of our materials

and establish correlation with our test results


Field calibration of LLAP design models

• A cooperative two-pronged approach

• Austroads project to enhance the design of asphalt

pavements (Dr Erik Denneman project leader)

– Will source data on the performance of UK LLAP sections for

ARRB TR and AAPA evaluation

– Will explore US NCHRP 9-44a project to introduce fatigue

endurance limit and healing

• AAPA will liaise with NCAT and access their field trials

and data to calibrate laboratory / field E* relationship

• A very positive direction that may substantially advance

the outcomes and so minimise waste and risk, and

enhance the sustainability of asphalt pavements


Calibration of materials models - AAPA

• With confirmation that our mix characteristics

correlate we can utilise NCAT performance data with

confidence

• Access NCAT full scale pavement trial data

• Correlate dynamic modulus estimates from back

analysis of deflection data

• Request made of NCAT to advise the results of their

studies into the laboratory / field estimates of E*

relationship

• Publication believed to be imminent


• Substrate conditions / bearing

capacity

• Accurate layer dimensions

• Load pulse shape and duration

• Temperature profile at deflection

test

• Wheel load and strain response

• Combined data will provide

unique ability to improve

precision in E* estimates

• Adequacy of design

assumptions endorsed when

generated and measured

cumulative strain distributions

correlate

NCAT DATA


Calibration of materials models - AAPA

• NCAT have agreed to work with us in alliance

• First approach is a formal follow up on their

correlation studies / conclusions

• Next issue is the mechanics of how we can access

raw data for our analysis and avoid overwhelming

• Physical exchange of personnel would seem the

optimum solution – candidates


Additional field trials – significant potential

• Both U Sunshine Coast and U Curtin have acquired

AMPT

• Both facilities are working with road agencies to

construct and instrument field trials

• AAPA has an advisory role to assist the selection and

placement of instrumentation to ensure best data for

laboratory correlations

• The universities offer the very great benefit of an

ongoing stream of candidates to ensure the continuity

of monitoring and analyses over time


Summary and conclusions

• The AAPA LLAP design concept has been peer

reviewed and has preliminary endorsement

• The national asphalt mix characterisation study is

near completion with good correlation with NCAT

• The critical validation phase is underway and LTPP

data is available to calibrate the limiting distribution

of strain

• LLAP implementation will incorporate thickness

design, material design and construction guidelines –

the latter is equally or more vital to LLAP


ASPHALT MASTER CLASS

NOVEMBER 2012

Update - AAPA Project

Asphalt Pavement Solutions – For Life

Development and calibration of a

Long Life Asphalt Pavement design

methodology

Ian Rickards

Consultant, AAPA

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