Update on Work on Simple Mixture Durability Tests and Plans for the MnROD-NCT Partnership to Validate Cracking Tests 1
FHW ccelerated Loading Facility 2
Tests Conducted Test Method Overlay Tester Tex-248-F modified by NCT SCB Louisiana LTRC method, draft SHTO IDT Nflex Factor NCT, draft SHTO Cantabro SHTO TP 108-14 I-FIT (tested by UIUC) SHTO TP 105-13 Test specimens were made from SGC samples compacted to 65 gyrations Using N design specimens provides the quickest and simplest path to implementation for any of these durability performance tests. Sealed buckets of mix were reheated, weighed out, then brought back to the compaction temperature before SGC compaction. 3
Cracking (inches) Cracking Performance Measured 1600 1400 1200 1000 800 600 400 200 0 20 ft. - 100,000 200,000 300,000 400,000 500,000 LF Passes Lane 1 Lane 2 Lane 3 Lane 4 Lane 5 Lane 6 Lane 7 Lane 9 Lane 11 Issues with Loading of Lane 8 and 10 4
s-built Construction sphalt Thickness Base Stiffness 5
1. Calculate Max. Tensile Strain Input Load Tire Pressure C Modulus Subgrade Modulus gg. Base Thickness Value 14,200 lbs. 100 psi 761 ksi 8 ksi 22 in. Poisson s ratios C = 0.35 Base = 0.40 Subgrade = 0.45 6
2. Calculate Max. Tensile Strain Lane sphalt Thickness Base Modulus Maximum (in.) (ksi) tensile strain Strain Ratio 1 4.56 20.1 321 1.0 2 4.57 20.1 320 1.0 3 4.42 15.3 364 1.13 4 4.53 16.5 346 1.08 5 4.03 15.4 397 1.24 6 4.6 17.9 332 1.03 7 4.28 17.2 360 1.12 8 4.5 15.1 359 1.12 9 4.14 15.3 387 1.21 10 4.23 10.9 424 1.32 11 4.04 12.1 430 1.34 7
3. Relationship between fatigue life and tensile strain N f = α 1 1 ε T α 2 N f = cycles to failure ϵ T = strain level at the reference test temperature α 1, α 2 = transfer function regression constants set α 2 = 5.21 verage of TT Group Exp. mixes, range 4.2 to 6.5 Lane 1 N f = 416,000 passes to 20 of cracking Solve for α 1 : α 1 = 4.7641 E18 8
4. Est. N f for Each Strain Lane sphalt Thickness Base Modulus Maximum Ratio to Est. Nf (in.) (ksi) tensile strain Lane 1 1 4.56 20.1 321 416,000 1.00 2 4.57 20.1 320 422,818 0.98 3 4.42 15.3 364 216,096 1.93 4 4.53 16.5 346 281,448 1.48 5 4.03 15.4 397 137,495 3.03 6 4.60 17.9 332 349,024 1.19 7 4.28 17.2 360 228,901 1.82 8 4.50 15.1 359 232,243 1.79 9 4.14 15.3 387 157,040 2.65 10 4.23 10.9 424 97,591 4.26 11 4.04 12.1 430 90,701 4.59 9
5. djust Measured LF Passes Lane to 20 ft. of Cracking Ratio to Lane 1 Measured Passes to 20 ft. of Cracking 10 djusted Passes to 20 ft. of Cracking 1 1.00 416,000 416,000 2 0.98 -- 3 1.93 67,000 128,980 4 1.48 121,000 178,847 5 3.03 45,000 136,151 6 1.19 156,000 185,936 7 1.82 41,000 74,512 8 1.79 -- -- 9 2.65 296,000 784,106 10 4.26 -- -- 11 4.59 111,000 509,099
Cantabro Test Primarily used for OGFC mixes One compacted specimen placed in L brasion drum at a time No Steel Balls 300 drum revolutions Calculate mass loss 11
Modified Overlay Test Method modified by NCT Displacement = 0.381 mm Cycle = 1 Hz Failure = peak of normalized load x cycle Conducted in MPT @ 25 C Triplicates 12
rea to Peak Load (kn-mm) Semi-Circular Bend Test (LTRC) 50 mm thick specimens Ram rate = 0.5 mm/min. Notch depths of 38.1, 31.8, 25.4 mm Triplicates 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 y = -0.0388x + 1.9336 R² = 0.70 15 20 25 30 35 40 45 Specimen Notch Length (mm) 13
Illinois Flexibility Index Test (I-FIT) Tests conducted by Univ. of Illinois Reheated mix, no aging Specimens compacted to 7 ± 0.5% air voids 4 SCB specimens per SGC pill 50 mm thick SCB specimens Notch 1.5 mm wide, 15 mm deep Loading Rate = 50 mm/min. Test Temp. = 25 C 14
Stress (kpa) 50 mm thick specimens Ram rate = 50 mm/min. Temp. = 25 C IDT Nflex Factor rea under σ vs. έ to post peak inflection point divided by slope at that point 1200 1000 y = 0.0003x 6-0.0268x 5 + 0.8303x 4-11.238x 3 + 49.595x 2 + 122.61x - 8.435 R² = 0.9988 800 600 400 200 Toughness = area calculated by integrating polynomial inflection point from 2 nd derivative of fit polynomial Nflex factor = inspired by IL-SCB method Toughness at inflection pt. slope at inflection pt. 0 0 5 10 15 20 25 30 Est. Horizontal Strain (%) 15
11 1 9 4 6 2 7 8 3 5 LF mixes Cantabro Results Tukey Statistical vg. Cantabro Loss (%) Groupings 0.0% 2.0% 4.0% 6.0% 8.0% 10.0% 12.0% 14.0% 40%RP HM 64-22 285 5%RS HM 64-22 285 40%RP HM 58-28 285 B 5%RS None 64-22 240 B 40%RP Foam 58-28 240 B C 20%RP HM 64-22 285 B C 20%RP Chem 64-22 240 B C 20%RP Foam 64-22 240 B C No RP or RS 64-22 285 B C 40%RP Chem 58-28 240 C verage COV = 19% 16
Cantabro Loss (%) Cantabro LF Correlation 12% 10% 8% 6% 4% 2% y = -0.02ln(x) + 0.1676 R² = 0.5371 0% 0 50 100 150 200 250 300 350 400 450 LF Passes to 20 feet of Cracking (thousands) 17
Cantabro Loss (%) Cantabro Corrected LF Correlation 12% 10% 8% 6% 4% 2% y = 0.3688x -0.312 R² = 0.5884 0% 0 100 200 300 400 500 600 700 800 900 Corrected LF Passes to 20 feet of Cracking (thousands) 18
7 3 5 1 2 6 11 8 4 9 LF mixes Overlay Test Results Tukey Statistical Groupings Overlay Test Cycles to Failure 0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 20%RP Foam 64-22 240 20%RP Chem 64-22 240 40%RP HM 58-28 285 40%RP Chem 58-28 240 20%RP HM 64-22 285 Lane 9 Results 3,880 3,893 8,094 13,687 B B B B 40%RP Foam 58-28 240 B No RP or RS 64-22 285 B 40%RP HM 64-22 285 B 5%RS HM 64-22 285 B 5%RS None 64-22 240 B verage COV = 32% 19
OT-NCT Cycles to Failure OT-NCT LF Correlation 8,000 7,000 6,000 5,000 y = 610.24x 0.3654 R² = 0.467 4,000 3,000 2,000 1,000 0 0 50 100 150 200 250 300 350 400 450 LF Passes to 20' of Cracking (thousands) 20
OT-NCT Cycles to Failure OT-NCT Corrected LF Correlation 8,000 7,000 6,000 y = 291.6x 0.4557 R² = 0.664 5,000 4,000 3,000 2,000 1,000 0 0 100 200 300 400 500 600 700 800 900 Corrected LF Passes to 20' of Cracking (thousands) 21
8 4 3 7 1 5 6 2 11 9 LF Mixes SCB-LTRC Results 20%RP Foam 64-22 240 40%RP Chem 58-28 240 40%RP Foam 58-28 240 20%RP HM 64-22 285 40%RP HM 64-22 285 No RP or RS 64-22 285 5%RS None 64-22 240 5%RS HM 64-22 285 20%RP Chem 64-22 240 40%RP HM 58-28 285 Maghsoodloo s Statistical Groupings Jc (kj/m2) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 B B B B verage COV for rea to Peak Load = 27% 22
SCB-LTRC Jc (kj/m3) SCB-LTRC LF Correlation 1.0 0.9 0.8 0.7 0.6 0.5 y = 0.0507ln(x) + 0.4151 R² = 0.0558 0.4 0.3 0.2 0.1 0.0 0 50 100 150 200 250 300 350 400 450 LF Passes to 20' of Cracking (thousands) 23
SCB-LTRC Jc (kj/m3) SCB-LTRC Corrected LF Correlation 1.0 0.9 0.8 0.7 0.6 y = 0.1237ln(x) - 0.0157 R² = 0.3032 0.5 0.4 0.3 0.2 0.1 0.0 0 200 400 600 800 1000 Corrected LF Passes to 20' of Cracking (thousands) 24
5 3 7 6 11 8 4 9 2 1 LF mixes IFIT Flexibility Index Flexibility Index 0 2 4 6 8 10 12 No RP or RS 64-22 285 40%RP Foam 58-28 240 20%RP Foam 64-22 240 20%RP Chem 64-22 240 40%RP HM 58-28 285 40%RP Chem 58-28 240 20%RP HM 64-22 285 5%RS None 64-22 240 5%RS HM 64-22 285 40%RP HM 64-22 285 verage COV = 16% 25
Flexibility Index Flexibility Index LF Correlation 12 10 8 6 4 y = 3.5752ln(x) - 11.987 R² = 0.9038 2 0 0 100 200 300 400 500 LF Passes to 20' of Cracking (thousands) 26
Flexibility Index Flexibility Index Corr. LF Correlation 12 10 8 6 4 2 y = 2.9597ln(x) - 11.311 R² = 0.5722 0 0 100 200 300 400 500 600 700 800 900 Corrected LF Passes to 20' of Cracking (thousands) 27
5 3 7 6 1 11 8 4 9 2 LF mixes IDT Nflex factor Nflex Factor Tukey Statistical Groupings 0 20 40 60 80 100 120 140 160 180 40%RP Foam 58-28 240 20%RP Foam 64-22 240 B 20%RP Chem 64-22 240 B 40%RP HM 58-28 285 B 40%RP Chem 58-28 240 B No RP or RS 64-22 285 B 20%RP HM 64-22 285 B C 5%RS None 64-22 240 C D 5%RS HM 64-22 285 D 40%RP HM 64-22 285 D verage COV = 11% 28
IDT-Nflex factor Nflex Factor LF Correlation 160 140 120 100 80 y = 13.406x 0.3881 R² = 0.5839 60 40 20 0 0 50 100 150 200 250 300 350 400 450 LF Passes to 20' of Cracking (thousands) 29
IDT-Nflex factor Nflex Factor LF Correlation 160 140 120 100 80 y = 10.953x 0.3768 R² = 0.503 60 40 20 0 0 100 200 300 400 500 600 700 800 900 Corrected LF Passes to 20' of Cracking (thousands) 30
Preliminary ssessment Test Time 1 COV Sens. Corr. R 2 Cantabro 40 min. 19% B 0.59 Mod. OT 2 days 32% C 0.66 SCB-LTRC 1.5 days 2 27% 3 C 0.30 I-FIT 5 hours 11% 0.57 IDT Nflex factor 4 hours 11% 0.50 1 once Ndes specimens are cooled. No aging. 2 requires five SGC specimens 3 COV of Work (area under load-def. curve) 31
Stress (kpa) IDT Nflex factor 50 mm thick specimens Ram rate = 50 mm/min. Temp. = 25 C rea under σ vs. έ to post peak inflection point divided by slope at that point 1200 1000 y = 0.0003x 6-0.0268x 5 + 0.8303x 4-11.238x 3 + 49.595x 2 + 122.61x - 8.435 R² = 0.9988 inspired by IL-SCB method 800 600 400 200 Toughness = area calculated by integrating polynomial inflection point from 2 nd derivative of fit polynomial Nflex factor = Toughness at inflection pt. slope at inflection pt. 0 0 5 10 15 20 25 30 Est. Horizontal Strain (%) 32
Refining Nflex Factor Draft test method, SHTO format Phase 1 Experiment Effect of temperature - completed Effect of loading rate Phase 2 Experiment Effect of asphalt content Effect of air voids Effect of PG grade PMLC Mixes from TT E7B virgin mix, hybrid binder E8B RP & RS, PG 76-22 LMLC Mixes virgin mixes Short & Long Term ged 33
12 10 8 6 4 2 0 E07B Virgin mix, Hybrid 76-22 binder 15% of Lane rea Cracking E7B 0 50 100 12 10 8 6 4 2 0 E08B 0 50 100 E8B 20% RP 5% RS, SBS 76-22 virgin binder 73.4% of Lane rea Cracking 34
Tensile Stress (kpa) Tensile Stress (kpa) Refining Nflex Factor 3,500 3,000 2,500 2,000 1,500 1,000 500 0 E8B 10 C 17.5 C 25 C 0.0 0.2 0.4 0.6 0.8 1.0 Horizontal Strain 3,500 3,000 2,500 2,000 1,500 1,000 500 0 E7B 10 C 17.5 C 25 C 0.0 0.2 0.4 0.6 0.8 1.0 Horizontal Strain Mix E8B (brittle) E7B (ductile) Test Temp. 10 17.5 25 10 17.5 25 Poisson s ratio 0.21 0.23 0.32 0.21 0.30 0.28 Toughness 755 813 799 1114 954 720 Brittleness slope -48,855-27,434-10,104-15,583-4,099-2,273 Nflex Factor 14.3 37.8 82.2 35 73.8 235.9 316.5
NCT + MnROD Cracking Group Experiments
Objectives and Goals Objective: validate laboratory cracking tests by establishing correlations between the test results and measured cracking in real pavements using real loading conditions Goals: evaluate various tests based on: Relatability to field performance. Practicality of the tests for mix design verification and quality control testing. bility to accommodate recycled materials, new and future additives, and mix combinations.
Cracking Group Sponsors Washington Oregon Nevada California Montana Idaho Wyoming Utah Colorado North Dakota South Dakota Nebraska Kansas Minnesota Iowa Wisconsin Missouri Michigan (upper pennisula) Illinois Michigan Indiana Kentucky Tennessee Ohio New York Pennsylvania West Virginia Vermont New Hampshire Delaware Maryland Virginia North Carolina Maine Massachusetts Rhode Island Connecticut New Jersey FHW rizona New Mexico Oklahoma rkansas Mississippi labama (DOT & DEM) Georgia South Carolina Texas Louisiana Florida
Scope NCT Test Track Top-down cracking MnROD Low-temperature cracking
Top-Down Cracking Sections Cracking Group sections 7 200-ft. sections each section instrumented Surface Layer 1.5 Intermediate Layer 2.25 Base Layer 2.25 Granular base 6 Stiff track subgrade infinite HiM mix 40
Tests for Top-Down Cracking Resistance NCT is conducting these tests on both LMLC and PMLC samples that are aged and unaged. SCB-L SCB-IL OT-TX OT-NCT Energy Ratio Nflex Factor Cantabro Materials were sampled for complementary studies funded by sponsoring agencies. 99 buckets of mix sampled per test section.
NCT Cracking Group Sections Section Surface Mix Description N1 20% RP (0.20 binder ratio) PG 67-22 N2 Same as N1 with 96% in-place density N5 Same as N1 except 0.5% low C, low density N8 20% RP & 5% RS with PG 67-22 S5 35% RP with PG 58-28 S6 Same as N1 with HiM PG76-28E S13 rizona style asphalt-rubber mix cracking expectation low med. high 42
NCT CG Experiment Status Test sections built in ugust 2015 Const. QC data & baseline field data summarized Trafficking began Oct. 8, 2015 2.5 million ESLs, no cracking yet FWD testing and response data PMLC testing began Oct.1, 2015 Energy Ratio testing completed Complete experiment in 3 year cycle 43
Cantabro Loss (%) Cantabro Cracking Group Mix Designs 14 12 10 y = -4.5293x + 31.884 R² = 0.9077 8 6 4 2 0 y = -4.5355x + 27.453 R² = 0.8533 y = -2.9532x + 21.275 R² = 0.8745 3 4 5 6 7 8 Total C Content (%) 9.5 mm NMS 19 mm NMS 12.5 mm NMS - Z 12.5 mm NMS - FL 44
Cantabro Loss (%) Cantabro Cracking Group Mix Designs 14 12 10 8 y = 1.2221x + 1.1764 R² = 0.723 6 4 2 0 Z Rubber 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 Specimen ir Voids (%) 45
NCT/MnDOT Partnership Cracking Group Experiment MnROD Test Section Update National Center for sphalt Technology uburn, labama December 9, 2015
Site Location MnROD Mainline MnROD Low Volume Road Cracking Group Cells 16-23
Test Section Layout 16 17 18 19 20 21 22 23
Proposed Pavement Sections
sphalt Mixtures CELL NO 16 17 18 19 20 21 22 23 MIX DESIGNTION SPWEB540L SPECIL SPWEB540L SPECIL-1 SPWE540L SPECIL-2 SPWEB530L SPECIL-3 SPWEB540 SPECIL SPWEB540C SPECIL SPWEB540C SPECIL-1 SPWEB540I SPECIL MX GG SIZE (mm) BR % (1) RP % (2) RS % (3) ir voids at N design N design BINDER GRDE 12.5 65 30 5 4.0 80 PG 64S-22 12.5 77 20 3 4.0 80 PG 64S-22 12.5 80 20-4.0 80 PG 64S-22 12.5 80 20-3.0 100 PG 64S-22 12.5 70 30-4.0 80 PG 52S-34 12.5 80 20-4.0 80 PG 58H-34 12.5 80 20-4.0 80 PG 58H-34 12.5 85 15-4.0 80 PG 64E-34 COMMENTS 3139 modified for limestone Highly modified asphalt binder
Cracking Modes and Testing Types of cracking to be investigated Low temperature a given Top-down likely Fatigue also possible Select appropriate post-construction testing Low temp: DCT-MN and SCB-MN Intermediate temp: I-FIT (SCB-IL) Top down, fatigue: Overlay Tester, BB Fatigue ME Design: E* Loose mix, cores dditional: BBR mix beams (related study, separate funding)
Schedule Pre-bid meeting May 4 Letting - May 20 Mix Designs July & ugust Construction - September
92nd PT nnual Meeting and Technical Sessions The 2017 nnual Meeting will be held March 19-22, 2017 The Island Hotel, Newport Beach, California US Our 2017 venue PT Office: 6776 Lake Drive, Suite 215 Lino Lakes, MN 55014 Phone: 651-293-9188 Fax: 651-293-9193 or Email: aapt@aapt.comcastbiz.net 2017 Call for Papers The ssociation of sphalt Paving Technologists is actively soliciting paper offers for its 2017 nnual Meeting and Technical Sessions. Papers reporting on studies concerning any aspect of asphalt paving technology or related fields are considered. These can include research, design, construction and maintenance issues dealing with all types of asphalt binders, asphalt mixtures, and pavement applications including innovative ideas and improvements to current practice. Papers will be considered for presentation at the nnual Meeting which is attended by specialists from academia, research organizations, material producers, contractors, national and state authorities, and consultants from around the world. Papers offered for the 2017 nnual Meeting must be submitted through the PT website. Important dates May 1, 2016 web site open for paper submission ugust 15, 2016 - deadline for submitting papers November 4, 2016 - notification of paper acceptance December 2016 - registration open March 19 to 22, 2017 - annual meeting and technical sessions For current information please check our web site at: http://www.asphalttechnology.org