NCHRP-IDEA Projects 84 and 104 — Academia/Government/Industry Collaboration That Pays Off!

1. 5% EVA (high MW) ° -30 C -24 C ° 5% EVA (low MW) 5% SBS radial SBS triblock diblock 5% SB (with 0.2% Sulfur) AAG (unmodified) 60 0 20 40 80 Fracture Energy (J/m2) NCHRP-IDEA Projects 84 and 104 — Academia/Government/Industry Collaboration That Pays Off! Improved Asphalt Binder Specification Grading Principal Investigator Simon A.M. Hesp, Queen’s University, Kingston, Ontario Co-Principal Investigator Kai K. Tam, Ministry of Transportation of Ontario, Downsview, Ontario Concept and Innovation Ontario and Alberta Pavement Trials Main Research Findings Large Variations for Same AASHTO M320 Grade A large number of studies have established that the asphalt grading system developed under the Strategic Highway Research Program should be improved. An extended bending beam rheometer (BBR) test protocol provides grades that will more effectively eliminate transverse cracking in service compared to the original BBR method. Simple compact tension tests can measure fracture energy (Gf) and crack opening displacement (COD) under conditions of tensile constraint in a notched asphalt binder sample in the brittle state with high reproducibility. A simple double-edge notched tension test can measure the essential and plastic works of fracture in the ductile state (we and wp) as well as the crack opening displacement (COD) providing measures of resistance to ductile failure. It has been established that a specification system based on these performance-based parameters (i.e., PG XX-YY, Gf, COD, we and wp) is able to provide superior performance grading for all binders, irrespective of their origin or method of manufacture. Field Monitoring of Pavement Trial Sections • Binders of exact same AASHTO M320 grade can show very significant differences in transverse cracking. • Many binders crack at temperatures above their limiting BBR (AASHTO M320) or BBR + DTT (MP1a) temperatures. Laboratory Investigation • Physical aging, notch sensitivity, chemical aging (beyond RTFO/PAV), and traffic-induced fatigue cracking are likely contributing factors to premature transverse cracking. • Brittle and ductile fracture energies vary widely for binders of identical grade. How this affects cracking severity will be investigated with the newly constructed test roads. 1991 C-SHRP Trial on Highway 631 Hearst Hwy 631 C-SHRP (1991) Timmins Hwy 655 (2003 & 2007) 750 1997 515 Cracks/km 2003 500 Bracebridge Hwy 118 (1994) 236 Lamont Hwy 637:02 C-SHRP (1991) 250 Ottawa Hwy 417 (2006) 74 49 14 5 2 5 0 Sections: Toronto Hwy 427 (2008) A AA BB B Petawawa Hwy 17 SPS-9A (1997) M320 grades: 52-33 52-33.5 46-37 52-33 CGSB grades: 150-200B 150-200A 150-200AA 150-200B A Total of 50 Test Sections Specifically Dedicated to Low-Temperature Studies Calculated Minimum Pavement Temperatures (Kapuskasing): -32oC, -33oC (1994), -33oC (1996), -30oC (1999)… COLDEST: -33oC Premature Cracking Due to Physical Aging Morphology Relates to Performance … Simple Performance-Based Binder Tests Research Product: Three Test Methods 655-1 655-2 655-5 LS-308: Performance Grade of Physically Aged Asphalt Cement Using Extended Bending Beam Rheometer Method LS-299: Asphalt Cement’s Resistance to Fatigue Fracture Using Double-Edge-Notched Tension (DENT) Test LS-298: Asphalt Cement’s Resistance to Low Temperature Fracture Using Compact Tension (CT) Test 1996 SPS-9A Trial on Highway 17 Compact Tension (LS-298) Low Temperatures: Brittle-to-Ductile Transition, Tgrade, after Physical Hardening Fracture Energy, Gf, and Critical Crack Opening Displacement, COD, in Brittle State Intermediate Temperatures: Essential and Plastic Works of Fracture, we and wp, and Critical Crack Opening Displacement, COD, in Ductile State Extended BBR (LS-308) 180 2002 169 Cracks/km 2003 120 65 52 52 60 Aluminium Inserts RR-4L RR-7L E-009 7 7 0 0 0 Double-Edge-Notched Tension (LS-299) A Much Improved Binder Grading Method: • Determines an Accurate Grade Temperature • Assesses Binder Fracture Energies in Brittle and Ductile States • Accounts for the Effects of Physical Aging and Traffic Sections: 02 03 60 61 L AASHTO M320: -41 -35P -31 -35 MTO LS-308: -37 -29 -18 (!) -29 Ligaments (L): 5, 10, 15 and 20 mm Calculated Minimum Pavement Temperatures (CFB Petawawa): -24.7oC (1999), -26.5oC & -27.2oC (2003)… COLDEST: -27oC But Is Hard to Quantify! Asphalt Binder and Mixture Testing Improved Prediction for Cracking Onset Tests Show High Reproducibility and Ability to Discriminate Modification Technologies Highway 118 and 17 Tests Sections That Cracked Prematurely Compact Tension Double-Edge-Notched Tension SectionCracks/km 118-3 45 118-4 18 118-5 37 17-3 65 17-5 52 3 4 5 3 5 3 4 5 3 5 3 4 5 3 5 3 4 5 3 5 3 4 5 3 5 6.0 4.0 2.0 0.0 -20 -20 60 40 20 0 AAL + SBS(r) + SBS(l) + RET + SB(d) + PPA DENT SBS(r) PG 70-28 100 mm/min 25oC Force (N) -27 -27 COD (cm) T grade Cold Lake (oC) Simple Performance Test Compact Tension Double-Edge-Notched Tension -34 -34 Temperature Range for Start of Cracking COLDEST: -27 C -41 -41 M320-1h MP1a-1h LS-308-3d MP1a-3d G - 3d f -40 -34 -28 -22 -20 15 5 10 20 0 one-hour soak three-day soak AASHTO M320 Grade (oC) Displacement (cm) Grading Methods Nature’s Way of Accelerated Pavement Testing in Northern Ontario Large Range in Ductile Fracture Performance Summary and Further Work 2003 Trial on Highway 655 10 Limiting Temperatures April 2004 (8 months after construction) July 2005 Asphalt binders of the exact same AASHTO M320 grade can perform very differently after long-term service. December 2003 - February 2004 l 0 AASHTO M320: 58-35 52-35 64-36 64-36 64-36 64-35 64-35 MTO LS-308: -10 58-29 52-29 64-34 64-26 64-32 64-30 64-31 Variations in physical aging and traffic-induced fatigue are likely causes of accelerated transverse cracking. l l 1.5 1.5 T, oC -20 Mix COD (mm) -30 1.06 Mix we (kJ.m-2) .99 Fracture energies in the brittle and ductile regimes vary 1.0 1.0 l -40 .79 .77 depending on crude source and modification technology. .71 .67 .63 .53 10 .52 .53 Comprehensive mixture tests and full-scale trials are ongoing in Ontario to calibrate the newly proposed grading tests. .51 .49 .43 l .44 0.5 0.5 December 2004 - February 2005 0 T, oC -10 Three test sections were badly damaged with a total of ~150 m of cracks after their first winter and ~300 m after their second winter. The cracking mainly occurred in the left (inner) wheel path of the south-bound lane due to heavy truck traffic and high thermal stresses. In spring 2005, several of the wheel path cracks had already started to sprout transverse cracks. The data in the next figure is able to explain the vast performance differences between binders of identical PG XX-34 AASHTO M320 grades. 0 Acknowledgments 0 -20 Cracking Distress 655-1 655-2 655-3 655-4 655-5 655-6 655-7 -30 Wheel Path, 2004 (m): 0 60 40 43 0 5 0 A. Andriescu, A. Basu, M. Gale, S. Iliuta, M.O. Marasteanu, P. Marks, T. Masliwec, L.E. Moran, S.D. Roy, M.O. Zhao, and others. Ministry of Transportation of Ontario,National Cooperative Highway Research Program – Innovations Deserving Exploratory Analysis, and Natural Sciences and Engineering Council of Canada E.I. du Pont of Canada, Imperial Oil of Canada, and McAsphalt Industries l -40 Wheel Path, 2005 (m): 0 113 52 92 1 0 1 Only 4 months after construction the Highway 655 trial was hit with extreme temperatures. The surface reached a record low of –34oC twice in January 2004. So far the surface has reached below or near –30oC for a total of 15 times! Both high essential works of fracture and crack opening displacements are desirable for resisting wheel path cracking which can seriously aggravate transverse cracking. The binder used in 655-1 physically ages less and the one used in 655-2 ages more compared to the others. (See Andriescu et al., AAPT 2005 and Bodley et al., AAPT 2007) l l