Update on Work on Simple Mixture Durability Tests and Plans for the MnROAD-NCAT Partnership to Validate Cracking Tests

Transcription

1 Update on Work on Simple Mixture Durability Tests and Plans for the MnROD-NCT Partnership to Validate Cracking Tests 1

2 FHW ccelerated Loading Facility 2

3 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 I-FIT (tested by UIUC) SHTO TP 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

4 Cracking (inches) Cracking Performance Measured ft , , , , ,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

5 s-built Construction sphalt Thickness Base Stiffness 5

6 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 =

7 2. Calculate Max. Tensile Strain Lane sphalt Thickness Base Modulus Maximum (in.) (ksi) tensile strain Strain Ratio

8 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 = E18 8

9 4. Est. N f for Each Strain Lane sphalt Thickness Base Modulus Maximum Ratio to Est. Nf (in.) (ksi) tensile strain Lane , , , , , , , , , , ,

10 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 , , , , , , , , , , ,000 74, , , , ,099

11 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

12 Modified Overlay Test Method modified by NCT Displacement = mm Cycle = 1 Hz Failure = peak of normalized load x cycle Conducted in 25 C Triplicates 12

13 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 y = x R² = Specimen Notch Length (mm) 13

14 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

15 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 y = x x x x x x R² = 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 Est. Horizontal Strain (%) 15

16 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 %RS HM %RP HM B 5%RS None B 40%RP Foam B C 20%RP HM B C 20%RP Chem B C 20%RP Foam B C No RP or RS B C 40%RP Chem C verage COV = 19% 16

17 Cantabro Loss (%) Cantabro LF Correlation 12% 10% 8% 6% 4% 2% y = -0.02ln(x) R² = % LF Passes to 20 feet of Cracking (thousands) 17

18 Cantabro Loss (%) Cantabro Corrected LF Correlation 12% 10% 8% 6% 4% 2% y = x R² = % Corrected LF Passes to 20 feet of Cracking (thousands) 18

19 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 %RP Chem %RP HM %RP Chem %RP HM Lane 9 Results 3,880 3,893 8,094 13,687 B B B B 40%RP Foam B No RP or RS B 40%RP HM B 5%RS HM B 5%RS None B verage COV = 32% 19

20 OT-NCT Cycles to Failure OT-NCT LF Correlation 8,000 7,000 6,000 5,000 y = x R² = ,000 3,000 2,000 1, LF Passes to 20' of Cracking (thousands) 20

21 OT-NCT Cycles to Failure OT-NCT Corrected LF Correlation 8,000 7,000 6,000 y = 291.6x R² = ,000 4,000 3,000 2,000 1, Corrected LF Passes to 20' of Cracking (thousands) 21

22 LF Mixes SCB-LTRC Results 20%RP Foam %RP Chem %RP Foam %RP HM %RP HM No RP or RS %RS None %RS HM %RP Chem %RP HM Maghsoodloo s Statistical Groupings Jc (kj/m2) B B B B verage COV for rea to Peak Load = 27% 22

23 SCB-LTRC Jc (kj/m3) SCB-LTRC LF Correlation y = ln(x) R² = LF Passes to 20' of Cracking (thousands) 23

24 SCB-LTRC Jc (kj/m3) SCB-LTRC Corrected LF Correlation y = ln(x) R² = Corrected LF Passes to 20' of Cracking (thousands) 24

25 LF mixes IFIT Flexibility Index Flexibility Index No RP or RS %RP Foam %RP Foam %RP Chem %RP HM %RP Chem %RP HM %RS None %RS HM %RP HM verage COV = 16% 25

26 Flexibility Index Flexibility Index LF Correlation y = ln(x) R² = LF Passes to 20' of Cracking (thousands) 26

27 Flexibility Index Flexibility Index Corr. LF Correlation y = ln(x) R² = Corrected LF Passes to 20' of Cracking (thousands) 27

28 LF mixes IDT Nflex factor Nflex Factor Tukey Statistical Groupings %RP Foam %RP Foam B 20%RP Chem B 40%RP HM B 40%RP Chem B No RP or RS B 20%RP HM B C 5%RS None C D 5%RS HM D 40%RP HM D verage COV = 11% 28

29 IDT-Nflex factor Nflex Factor LF Correlation y = x R² = LF Passes to 20' of Cracking (thousands) 29

30 IDT-Nflex factor Nflex Factor LF Correlation y = x R² = Corrected LF Passes to 20' of Cracking (thousands) 30

31 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% once Ndes specimens are cooled. No aging. 2 requires five SGC specimens 3 COV of Work (area under load-def. curve) 31

32 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 y = x x x x x x R² = inspired by IL-SCB method 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 Est. Horizontal Strain (%) 32

33 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 LMLC Mixes virgin mixes Short & Long Term ged 33

34 E07B Virgin mix, Hybrid binder 15% of Lane rea Cracking E7B E08B E8B 20% RP 5% RS, SBS virgin binder 73.4% of Lane rea Cracking 34

35 Tensile Stress (kpa) Tensile Stress (kpa) Refining Nflex Factor 3,500 3,000 2,500 2,000 1,500 1, E8B 10 C 17.5 C 25 C Horizontal Strain 3,500 3,000 2,500 2,000 1,500 1, E7B 10 C 17.5 C 25 C Horizontal Strain Mix E8B (brittle) E7B (ductile) Test Temp Poisson s ratio Toughness Brittleness slope -48,855-27,434-10,104-15,583-4,099-2,273 Nflex Factor

36 NCT + MnROD Cracking Group Experiments

37 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.

38 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

39 Scope NCT Test Track Top-down cracking MnROD Low-temperature cracking

40 Top-Down Cracking Sections Cracking Group sections 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

41 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.

42 NCT Cracking Group Sections Section Surface Mix Description N1 20% RP (0.20 binder ratio) PG 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 S5 35% RP with PG S6 Same as N1 with HiM PG76-28E S13 rizona style asphalt-rubber mix cracking expectation low med. high 42

43 NCT CG Experiment Status Test sections built in ugust 2015 Const. QC data & baseline field data summarized Trafficking began Oct. 8, 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

44 Cantabro Loss (%) Cantabro Cracking Group Mix Designs y = x R² = y = x R² = y = x R² = Total C Content (%) 9.5 mm NMS 19 mm NMS 12.5 mm NMS - Z 12.5 mm NMS - FL 44

45 Cantabro Loss (%) Cantabro Cracking Group Mix Designs y = x R² = Z Rubber Specimen ir Voids (%) 45

46 NCT/MnDOT Partnership Cracking Group Experiment MnROD Test Section Update National Center for sphalt Technology uburn, labama December 9, 2015

47 Site Location MnROD Mainline MnROD Low Volume Road Cracking Group Cells 16-23

48 Test Section Layout

49 Proposed Pavement Sections

50 sphalt Mixtures CELL NO 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 PG 64S PG 64S PG 64S PG 64S PG 52S PG 58H PG 58H PG 64E-34 COMMENTS 3139 modified for limestone Highly modified asphalt binder

51 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)

52 Schedule Pre-bid meeting May 4 Letting - May 20 Mix Designs July & ugust Construction - September

53 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 Phone: Fax: or 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, deadline for submitting papers November 4, notification of paper acceptance December registration open March 19 to 22, annual meeting and technical sessions For current information please check our web site at: