Asphalt Perform ance Testing and Specification Developm ent Eshan - PowerPoint PPT Presentation

Asphalt Perform ance Testing and Specification Developm ent Eshan V. Dave, Ph.D. University of New Hampshire 57 th Annual Pennsylvania Asphalt Paving Association Conference Hershey, PA 18 th January 2017 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Overview  Introduction: Performance-based Specifications  Fracture Energy as Performance Measure  MnDOT Performance Based Specification – Regional Validation – Pilot Implementation – Sensitivity of Fracture Energy to Thermal Cracking Performance – Specification Refinement Efforts – Round Robin Testing  Summary & Conclusion 2 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Asphalt Perform ance Testing  Goals: –Identify mixtures prone to performance problems during the mix design process –Identify potential performance problems during production –Predict performance during mix design and production  Warranties  Performance Specifications –Evaluate new materials or design tools to improve performance 3 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Field Cracking and Volum etric Measures 25.0  26 Pavement Sections TCTotal (%/yr.2) 20.0  Field Cracking Rates 15.0 10.0 5.0 0.0 12.0% 14.0% 16.0% 18.0% 20.0% Voids in Mineral Aggregate 100.0 TCTotal x AC Th. (% x in./yr. 2 ) 80.0 60.0 40.0 20.0 0.0 0% 10% 20% 30% 40% 50% Recycled Asphalt Content, ABR 4 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Material Specifications  Specification Development Continuum –TRB Circular on “Development of Warranty Programs for HMA Pavements”  Use of performance tests in material specifications is an alternative to wide-spread warranty pavement requirements 5 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Challenges in Im plem entation of Perform ance Based Specifications  Availability of suitable performance indicator(s) – Requires a performance test  Implementation Needs: – Spec. needs to be relevant, repeatable, achievable, and reliable – Sampling and specimen conditioning  Cost – Manpower needs – Equipment needs  Other challenges: – Time limit on obtaining lab results – Teething problems 6 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Balanced Mix Design: ETG Definition  Asphalt mix design using performance tests on appropriately conditioned specimens that address multiple modes of distress taking into consideration mix aging, traffic, climate and location within the pavement structure Performance Pendulum (Shane Buchanan, Oldcastle) 7 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Cracking Process in Asphalt Materials Quasi-brittle fracture Load Load Softening CMOD Work of Fracture Crack Mouth Opening Displacement (CMOD) Crack Load formation Onset of damage δ c σ t Damage Zone Cracking 8 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Fracture Test Geom etries  Fracture tests on asphalt date back to 1971 Semi-Circular Bend (SCB) Single-edge Notched Beam (SE(B)) Direct Tension Disk-shaped Compact Tension (DCT) Fenix Test 9 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Disk-Shaped Com pact Tension (DCT) Test  ASTM D7313-13  Loading Rate: – Crack Mouth Opening Displacement – CMOD Rate = 1.0 mm/min  Measurements: – CMOD – Load P CMOD, u P 10 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Sem i-Circular Bend (SCB) Test  Multiple variants exist – Early work in Europe – Simultaneous cold (Marasteanu et al. – MN) and intermediate temperature (Mohamed et al. – LA) versions – Recent work from Al-Qadi et al. (IL)  AASHTO TP 105  AASHTO TP 105 (I-FIT) – Line load control, loading rate = 50 mm/min – Test temperature = 25 deg. C  Measurements: – Displacement – Load  Outcomes – Fracture Energy – Flexibility Index (FI) 11 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Fracture Param eters P P LL CMOD P Fracture work: Area m under Load-Displacement Load, P curve Fracture Energy, G f : S f Energy required to create unit fracture surface G f = Fracture Work, S f Fracture Area Displacement (CMOD or LL), u Flexibility Index, FI: FI = G f / m 12 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Specim en Preparations Core loading Notched holes 5 0 m m ( 2 inch) Gyratory Disk Specim en DCT Cut disk Notched into tw o halves SCB 13 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Current Adoption Efforts of Fracture Tests in Perform ance Based Specifications  Semi-Circular Bend (SCB) –LA Version Intermediate Temperature  Louisiana DOTD  Wisconsin for High RAM Projects (2014 and 2015) –IL and MN Version at Intermediate Temperature:  Illinois in pilot implementation stages: Combination of Hamburg Wheel Tracking Test and SCB Flexibility Index (I-FIT)  Disk-shaped Compact Tension (DCT) –City of Chicago –Illinois Tollways –Wisconsin for High RAM Projects (2014 and 2015) –Minnesota Department of Transportation  Discussed here 14 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Low Tem perature Cracking Pooled Fund Study  Primary Distress: Thermal cracking  Minnesota (Lead State), Connecticut, Iowa, Illinois, New York, North Dakota, Wisconsin  TPF-5(080): 2004 – 2006 (Phase-I) – Extensive evaluation of performance tests (binder and mixtures)  TPF-5(132): 2008 – 2012 (Phase-II) – SCB and DCT fracture energy tests evaluated for nine pavement sections – 4 and 7% air void level, short term and long term aging conditions – Outcome: Performance specifications with limited validation through five field sections 15 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Fracture Energy as Perform ance Measure: Results from Various Studies (~ 50 sections) 16 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Pooled Fund Study LTC Perform ance Specifications  Based on traffic levels  Limits based on: – Fracture energy test @ 10 º C above 98% reliability Superpave Low Temperature PG (PGLT) – Low temperature cracking performance model ( IlliTC ) Project Criticality / Traffic Level Limits High Medium Low (> 30M ESALs) (10 – 30M ESALs) (< 10M ESALs) DCT Fracture Energy 690 460 400 (J/m 2 ) IlliTC Cracking < 4 < 64 Not required Prediction (m/km) 17 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

MnDOT Im plem entation of Perform ance Specification 4. Specification refinement efforts 3. Determine sensitivity of (specimen conditioning, fracture energy to thermal practicality revisions etc.) cracking performance (2013) (2014-present) 2. Pilot I mplementation (2013) 5. Round- robin Testing (2014-16) I mplementation of Performance-based Specification 1. Regional (MnDOT) Validation of Performance Communications Specifications and Training (2011-2016) 18 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

MnDOT Im plem entation of Perform ance Specification 4. Specification refinement efforts 3. Determine sensitivity of (specimen conditioning, fracture energy to thermal practicality revisions etc.) cracking performance (2013) (2014-present) 2. Pilot I mplementation (2013) 5. Round- robin Testing (2014-16) I mplementation of Performance-based Specification 1. Regional (MnDOT) Validation of Performance Communications Specifications and Training (2011-2016) 19 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Developm ent and Im plem entation of MnDOT Perform ance Based Specifications  Started with LTC Specifications from Pooled Fund Study  Minnesota Regional Validation Studies (2011 – 2015) –18 sites and 26 sections  Companion sections –2004 – 2013 construction years –Captures different binder grades and aggregates in Minnesota –Different construction types: New construction, overlay, and full-depth reclamation –Different design traffic levels 20 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Local Validation Exam ple: Field Cracking Perform ance vs. Fracture Energy 100 RP 10 90 Percent Cracking (MnDOT) RP 5 80 70 60 50 40 30 20 10 0 0 1 2 3 4 5 6 7 8 Years in Service 550 500 RP 10 (PP) 1000 Fracture Energy (J/m 2 ) 450 Fracture Energy (J/m 2 ) RP 5 (GP) 800 400 350 600 300 400 250 200 200 326 150 100 0 182 0 10 20 30 40 50 60 70 50 TCTotal (%) 0 21 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017

Im plem entation of Perform ance Specification 4. Specification refinement efforts 3. Determine sensitivity of (specimen conditioning, fracture energy to thermal practicality revisions etc.) cracking performance (2013) (2014-present) 2. Pilot I mplementation (2013) 5. Round- robin Testing (2014-16) I mplementation of Performance-based Specification 1. Regional (MnDOT) Validation of Performance Communications Specifications and Training (2011-2016) 22 Lab Performance Testing, Eshan Dave, PAPA 01/18/2017