NCAT/MnROAD Cracking Group Update March 29, 2018
Outline Project background Laboratory testing Pavement response Performance observations 2
Cracking Group Experiment Primary objective Correlate lab cracking tests to field performance Constraints Short timeframe Range of expected cracking Suite of lab cracking tests being performed by MnDOT and NCAT Identify the test(s) that best correlate with each type of field cracking 3
HMA Mixtures Mixtures selected to achieve range of low-temperature cracking (LTC) potential Based on input from pooled-fund sponsor states Contractor selected, procured materials, submitted to NCAT NCAT performed mix designs Contractor produced/placed mixture 4
Pavement Design Inputs WB I-94 average daily traffic volume ~30,000 vehicles ~13% HC Flexible ESALs ~800k per year (design lane) ètraffic level 5 Soils: USDA Clay Loam, Loam AASHTO A-6 USCS Lean Clay (CL) Expected life ~10 yrs 5
MnROAD CG Construction Contract Construction of 8 mainline I-94 HMA test sections ~$1.2 million construction contract Project let Friday, May 20, 2016 è four bidders Construction schedule - Contract: July 11 thru October 15, 2016 Actual: July 18 thru October 14, 2016 Opened to Traffic - November 2, 2016 6
MnROAD CG Section Traffic Open to traffic - November 2, 2016 MnROAD 2017 NRRA construction No traffic from June 5 thru September 19, 2017 Approximately 900,000 ESALs to date 7
MnROAD Site MnROAD Mainline MnROAD Low Volume Road MnROAD Low Volume Road Cracking Group Cells 16-23 8
MnROAD Cracking Group Cells 9
Constructed Section Typical 10
Typical sensor layout Cells 17, 19, 21 11
Sensor layout Cell 23 12
MnROAD Mixtures Cell # NMAS Design RAP (%) Design RAS (%) QC Total ABR % Virgin Binder Grade QC Binder Content (%) Ndesign C16 (20% RAP/5% RAS) 12.5 20% 5% 42% 64S-22 5.0 80 C17 (10% RAP/5% RAS) 12.5 10% 5% 28% 64S-22 5.3 80 C18 (20% RAP/PG 64S) 12.5 20% 0% 24% 64S-22 5.1 80 C19 (Cell 18 w/ +binder) 12.5 20% 0% 22% 64S-22 5.7 100 C20 (30% RAP/52S-34) 12.5 30% 0% 37% 52S-34 5.0 80 C21 (20% RAP/58H-34) 12.5 20% 0% 24% 58H-34 5.2 80 C22 (Cell 21 w/ LMS) 9.5 20% 0% 23% 58H-34 5.4 80 C23 (15% RAP/ HiMA) 12.5 15% 0% 18% 64E-34 5.2 80
Density Acceptance Nuclear density gage approach Avoid coring within cell Density cores within transition area Adjust gage readings using core bulk densities 14
Adjusted HMA nuclear density DRIVING PASSING CELL Lift 1 Lift 2 Lift 1 Lift 2 16 92.3 93.2 91.7 93.2 17-91.7 95.6 91.8 18 92.0 92.2 93.9 93.0 19 94.4 93.7 94.5 93.6 20 91.3 94.9 93.4 94.4 21 93.9 93.8 94.0 94.8 22 91.5 92.4 91.2 92.2 23 92.4 92.1 92.3 92.2 15
All cells showed significantly higher density within mat as compared to confined and unconfined joints RDM can get as close as 6 inches from joints Relationship is unique, dielectric affected by aggregate type: Granite ~5 Limestone ~7
Air Voids vs. Dielectric 10.0 9.0 y = 4588.7e -1.328x R² = 0.78 y = 4226.3e -1.19x R² = 0.69 8.0 7.0 6.0 5.0 4.0 4.7 4.9 5.1 5.3 5.5 5.7
Cell 19 Dielectric/Density Results 18
Cell 16 Dielectric/Density Results 19
140 IRI (in/mi) / PASSING LANE 120 100 80 60 40 20 0 23 (HiMA) 22 (LMS) 21 (Typ. MnDOT mix) 20 (30% RAP) 19 (3% AV) 18 (20% RAP) 17 (10% RAP, 5% MWSS) 16 (20% RAP, 5% MWSS)
140 IRI (in/mi) / DRIVING LANE 120 100 80 60 40 20 0 23 (HiMA) 22 (LMS) 21 (Typ. MnDOT mix) 20 (30% RAP) 19 (3% AV) 18 (20% RAP) 17 (10% RAP, 5% MWSS) 16 (20% RAP, 5% MWSS)
NCAT/MnDOT Materials Testing Overview of mixtures Cantabro Tensile Strength Ratio (TSR) Hamburg Wheel Tracking Test (HWTT) 50 C and 45 C Illinois Flexibility Index Test (IFIT) IDT Creep & Strength (AASHTO T322) DCT Extracted binder properties 22
MnROAD Mixtures Cell # NMAS Design RAP (%) Design RAS (%) QC Total ABR % Virgin Binder Grade QC Binder Content (%) Ndesign C16 (20% RAP/5% RAS) 12.5 20% 5% 42% 64S-22 5.0 80 C17 (10% RAP/5% RAS) 12.5 10% 5% 28% 64S-22 5.3 80 C18 (20% RAP/PG 64S) 12.5 20% 0% 24% 64S-22 5.1 80 C19 (Cell 18 w/ +binder) 12.5 20% 0% 22% 64S-22 5.7 100 C20 (30% RAP/52S-34) 12.5 30% 0% 37% 52S-34 5.0 80 C21 (20% RAP/58H-34) 12.5 20% 0% 24% 58H-34 5.2 80 C22 (Cell 21 w/ LMS) 9.5 20% 0% 23% 58H-34 5.4 80 C23 (15% RAP/ HiMA) 12.5 15% 0% 18% 64E-34 5.2 80
Cantabro 10.0 9.0 8.0 Mass Loss, % 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 C16 C17 C18 C19 C20 C21 C22 C23
Design Tensile Strengths 180 160 140 Tensile Strength, psi 120 100 80 60 40 20 0 C16 C17 C18 / C19 C20 C21 C22 C23 Unconditioned Conditioned
200 180 160 QC Tensile Strengths (PMLC) Tensile Strength, psi 140 120 100 80 60 40 20 0 C16 C17 C18 C19 C20 C21 C22 C23 Unconditioned Conditioned
Tensile Strength Variation Cell Unconditioned Conditioned Difference, psi Difference, % Difference, psi Difference, % C16 12.5 8% -1.9-1% C17 43.8 34% 33.4 30% C18 / C19 13.8 10% -0.6-1% C20 13 16% 9.4 13% C21 27.2 28% 5.7 6% C22 51.2 60% -7-9% C23 24.8 28% 8.6 9%
Tensile Strength Ratio (TSR) 1.2 1.0 0.8 TSR 0.6 0.4 0.2 0.0 C16 C17 C18 / C19 C20 C21 C22 C23 Design TSR PMLC TSR
Hamburg Wheel Tracking Test (HWTT) 50 C water bath, typical Rut depths were not recorded past 12.5 mm. All testing was done at 50 C. Lower temp for softer binder grades 158 lb. load Cyclic testing 10,000 cycles (20,000 passes) 2 sets per mix typical Specimen V a = 7.0 ± 0.5% Failure = 12.5 mm rutting
Hamburg Wheel Tracking Test (HWTT) Rut depths were not recorded past 12.5 mm. All testing was done at 50 C.
Hamburg Wheel Tracking Test (HWTT) 14.0 12.0 Rut depths were not recorded past 12.5 mm. All testing was done at 50 C. 10.0 SIP = 7500 Passes SIP = 9500 Passes Rut Depth, mm 8.0 6.0 4.0 2.0 0.0 C16 C17 C18 C19 C20 C21 C22 C23 Avg. Rut Depth @ 10,000 passes (mm) Avg. Rut Depth @ 20,000 passes (mm)
Hamburg Wheel Tracking Test (HWTT) Rut depths were not recorded past 12.5 mm. All testing was done at 50 C. Testing conducted @ 45 C. Testing conducted at 45 C.
Illinois Flexibility Index Test (IFIT) 25 C 50 mm/min load rate Minimum of 6 replicates 50 mm thick specimens Notch Depth = 15 mm Notch Width = 1.5 mm Load vs. Axial Deformation Test until load < 0.1 kn Outlier evaluation 33
Illinois Flexibility Index Test (IFIT) FI = 0.01 G ) m
Illinois Flexibility Index Test (IFIT) 20.0 18.0 16.0 14.0 Rut depths were not recorded past 12.5 mm. All testing was done at 50 C. Flexibility Index 12.0 10.0 8.0 6.0 4.0 2.0 0.0 C16 C17 C18 C19 C20 C21 C22 C23
Cell ID IFIT Statistical Differences Flexibility Index Standard Deviation CV (%) Statistical Group Anticipated Cracking Potential C23 (15% RAP/ HiMA) 14.9 3.6 24 A Low C20 (30% RAP/52S-34) 12.3 4.8 39 A B C Moderate/High C21 (20% RAP/58H-34) 9.5 2.9 30 A B Moderate C17 (10% RAP/5% RAS) 8.7 2.1 24 A B High C18 (20% RAP/PG 64S) 7.9 1.9 25 B C Moderate C22 (Cell 21 w/ LMS) 7.1 1.4 20 B High C19 (Cell 18 w/ +binder) 6.2 1.6 26 B C Moderate C16 (20% RAP/5% RAS) 3.2 0.5 15 C High
Indirect Tension Test (IDT) AASHTO T 322-07 Specimens are cut from SGC cylinders (38 50 mm thick) Creep compliance at 0 C -10 C, and -20 C (constant load is applied for 100 sec) and tensile strength at -10 C Temperatures vary by material Thermal stress analysis conducted to determine critical temperature
AASHTO T 322 IDT CC&S Rut depths were not recorded past 12.5 mm. All testing was done at 50 C. Testing conducted @ 45 C. Testing conducted at 45 C.
Summary All cells had <10% ML from Cantabro testing Only Cell 22 plant mix failed TSR significantly Cells 16 19 & 23 passed Hamburg @ 50 C Cells with softer binder grades performed well @ 45 C in Hamburg IFIT results generally followed expected trends Cells with 64S-22 binders among the 5 worst HiMA and lower binder grades top 3 39
Remaining Work TX Overlay Test (8 cells) Bending Beam Fatigue (8 cells) Note: recently completed but not reviewed Dynamic Modulus (FHWA) Small Specimen E* (TBD) 40
1200 MnDOT DCT FE 1000 FRACTURE ENERGY, J/M^2 800 600 400 200 0 16 17 18 19 20 21 22 23 TEST SECTION LMLC Ave PMLC Ave THRESHOLD
CELL DCT Fracture Energy / PMLC DCT Testing Results (PMLC) N MEAN FE (J/m 2 ) CV (%) C23 (15% RAP/ HiMA) 15 668.1 14.7 A C21 (20% RAP/58H-34) 16 573.3 11.5 A B STATISTICAL GROUP C20 (30% RAP/52S-34) 15 507.8 14.8 B C C16 (20% RAP/5% RAS) 15 454.9 10.9 C D C19 (Cell 18 w/ +binder) 16 444.8 15.0 C D C17 (10% RAP/5% RAS) 15 425.4 14.5 D C18 (20% RAP/PG 64S) 13 419.2 10.6 D C22 (Cell 21 w/ LMS) 14 340.5 9.4 E Games-Howell method (95% confidence) Outliers removed (ASTM E178) 42
Binder Testing Results VIRGIN BINDER EXTRACTED (PAV) CELL RAP RAS SPEC PG CONT. PG CONT. PG Delta T c 16 64S-22 71.5-26.7-1.9 120.7-23.0 17 64S-22 73.2-26.2-2.1 64.5-27.0 18 64S-22 71.1-26.5-1.4 19 64S-22 70.8-25.8-0.2 86.5-19.8 20 52S-34 56.3-35.8 63.3-32.2-0.9 NA 21 58H-34 63.2-35.6 70.2-30.3-2.1 22 58H-34 63.1-36.5 72.0-30.0-3.5 23 64E-34 73.4-37.8 72.0-31.7-3.6 43
MnROAD Dynamic Data Processing
Dynamic Data Processing Goals Provide common platform between sites User-friendly Visual quality checks Rapidly build databases
DADiSP Data Processing MnROAD Truck
Access Databases
Pavement Response Data Sensor testing with: Dynatest FWD MnROAD truck Data processing Results to date 48
MnROAD Truck 17.1k 16.8k 16.5k 17.7k 11.7k 49
AVERAGE PEAK STRAINS and HMA MID-DEPTH TEMPERATURE 1600 35 mph 1400 1200 AVERAGE MICRO-STRAIN 1000 800 600 400 200 0 40 50 60 70 80 90 100 110 120 TEMPERATURE @ MID-DEPTH (F) C17 [64S-22, 28% ABR] C19 [64S-22, 22% ABR] C21 [58H-34, 24% ABR] C23 [64E-34, 18% ABR]
AVERAGE PEAK STRAINS and HMA MID-DEPTH TEMPERATURE 1600 5 mph 1400 1200 AVERAGE MICRO-STRAIN 1000 800 600 400 200 0 40 50 60 70 80 90 100 110 120 TEMPERATURE @ MID-DEPTH (F) C17 [64S-22, 28% ABR] C19 [64S-22, 22% ABR] C21 [58H-34, 24% ABR] C23 [64E-34, 18% ABR]
MINIMUM AIR TEMPERATURES / Oct-2016 through Mar-2018 30.0 20.0 10.0 MINIMUM AIR TEMPERATURE ( C) 0.0-10.0-20.0-30.0 12/18/2016, -31.0 12/31/2017, -29.4-40.0
1600 1400 Cumulative FI, DegC-days Low-Temperature Cracking Min Air Temp, C 0-5 1200 1000 800 600 400-10 -15-20 -25-30 -35 200-40 0 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018-45
Cell 23 longitudinal edge line
Cell 19 passing lane
Cell 18 passing lane
Summary Performance testing is nearly complete BBF recently completed No clear distinguishing performance observations to date Pavement sensor responses follow anticipated trends with respect to speed and temperature Magnitudes also reflect anticipated mixture stiffness results
Summary, cont. Some cracking has appeared Consult available construction information RDM, FWD, IC, IR, GPR, etc. Non-destructive forensics FWD, GPR, as examples Destructive forensics Coring Decision made as to whether these will spread Pre-emptive measures?
Acknowledgements Pooled fund sponsor states Hardrives, Inc. Ingevity (anti-strip additive) WSB and Associates, Inc. MnDOT: District 3 ORS MnROAD staff OMRR staff NCAT Kyle Hoegh, Dave Timm, and Hyung Jun Ahn (all PhD) 61
Thank you! 62