Thinlays What the research says

Transcription

1 Thinlays What the research says Mary Robbins, Ph.D. Ohio Research Institute for Transportation and the Environment (ORITE) Ohio University October 10, 2017 Ohio Transportation Engineering Conference Columbus, Ohio

2 Content Overview Thin Overlay Research Thinlays in Ohio 2

3 Thinlay Definition Thinlay = thin asphalt concrete overlay Nationally established term Denotes use for pavement preservation Structurally sound pavements How thin?? Typically ¾ 1 5/8 and greater [NAPA, 2014] 3

4 Thin AC Overlays Thin asphalt concrete overlays 2 or less [Chou et al., 2008 for Ohio DOT] 1.5 or less with small NMAS (typically 12.5 mm or less) [D. Newcomb, NAPA IS 135, 2009] [Peshkin et al., SHRP2-S2-R26-RR-2, 2011] Thin overlay: Ultra-thin overlay:

5 Thin AC Overlays Thin AC overlays NCHRP Synthesis 464 (M. Heitzman and D. Watson, 2014) Survey responses 43 agencies 8 private industry companies Source: M. Heitzman and D. Watson, NCHRP Synthesis 464 5

6 Overview Thinlays as a preservation treatment Pavement preservation defined a program employing a network level, long-term strategy that enhances pavement performance by using an integrated, costeffective set of practices that extend pavement life, improve safety and meet motorist expectations." Source: FHWA Pavement Preservation Expert Task Group [2005 FHWA memo] Preservation consists of work that is planned and performed to improve or sustain the conditionof the transportation facility in a state of good repair. Preservation activities generally do not add capacity or structural value, but do restore the overall condition of the transportation facility. [FHWA, 2016] 6

7 Overview Thinlays as a pavement preservation treatment Pavement Condition Preservation Rehabilitation Reconstruction Crack seal/fog seal Chip seal/micro surface Ultra thin overlay Thin overlay Thick overlay Mill/inlay; hot-in-place Mill/inlay; cold-in-place Full-depth Age Source: after J. Dietz, 2014 FHWA; R. Powell - NCAT 7

8 Thin AC Overlays for Pavement Preservation D. Newcomb,

9 Thin AC Overlays for Pavement Preservation NAPA IS 135 (D. Newcomb, 2009) Pavement evaluation and project selection Materials and mix design Construction and quality construction Performance 9

10 Synthesis on Thin AC Overlays M. Heitzman and D. Watson,

11 Synthesis on Thin AC Overlays (NCHRP Synthesis 464) Advantages of Thin Overlays Provides long service life (when placed over structurally sound pavements) Provides good riding surface Reduces noise (fine-graded mixes) Maintains grade and slope geometry Is easily maintained Is recyclable

12 Synthesis on Thin AC Overlays (NCHRP Synthesis 464) Design and Construction Aggregate Superpave quality standards Binder Often modified Compaction level 50 gyrations, locking point, other Testing constraints

13 Synthesis on Thin AC Overlays (NCHRP Synthesis 464) Design and Construction Source: M. Heitzman and D. Watson, NCHRP Synthesis 464

14 Synthesis on Thin AC Overlays (NCHRP Synthesis 464) Design and Construction As a general rule, only 40-60% improvement in ride quality can be expected with a single layer of asphalt mix.

15 Use of Thin AC Overlays/Thinlays Address functional distresses Intended only for structurally sound pavements Seal the pavement Extend service life Reduce life-cycle cost 15

16 Thin AC Overlay Research 16

17 Thin AC Overlay Research NCAT Test Track NCAT PG 2012 NCAT MnROAD PG 2015 Others 17

18 NCAT Pavement Test Track 1.7 mile closed-loop test facility 46 asphalt test sections (200 ft per section) 5 trucks operate 16 hours/day for two years Operational speed = 45 mph 10 Million ESALs in 2-year trafficking period Embedded instrumentation

19 First 03 Thinlay Experience 19

20 2003 NCAT Test Track Cycle Mississippi DOT 4.75 mm mix ¾ in thick 92.2% Theoretical Density PG Aggregate 69% Limestone 19% Gravel 12% Natural Sand

21 10 years and 33 million ESALs Later

22 14 years and 46 million ESALs Later

23 Finer/Smaller Blends Similar rutting performance to coarser/larger Longer path for crack propagation Higher effective binder content Better cracking/raveling performance. APAI 12/2/08 23

24 NCAT/MnROAD 2015 Preservation Group Study One Project Develop independentlife-extending benefit curves for a range of pavement preservation treatments, under varying traffic levels and climates Two Climates Alabama: Hot, wet, no-freeze Minnesota: Cold, wet, freeze Four Sites AL -LR 159 (Low Vol); US 280 (High Vol) MN CR 8 (Low Vol);US 169 (High Vol)

25 PG15 Thinlays 4.75 mm NMAS dense graded asphalt Stand alone test sections at ¾ thickness (virgin vs ABR) Thinlay Cape seals (¾ in combination with chip seals) 1 overlays on cold recycle mixes (CCPR& CIR, F & E) Open graded friction course (OGFC) 1 thinlays Varied tack Ultra thin bonded wearing course (UTBWC) ¾ Thickness

26 Thinlays in Ohio 26

27 Thin Lift AC in Ohio Previous experience with thin lift AC overlays ODOT Item 404 Smoothseal(Item 424 Fine graded polymer AC) 404 LVT 27

28 Thinlays in Ohio Industry sought to develop a Thinlay mix in Ohio: Cost-effective preservation alternate to surface treatments Lower cost than Item 424, Fine Graded Polymer Asphalt Acceptable friction Flexibility in design different traffic levels Performance Smooth ride Service life Rut resistance on heavy traffic roads Cracking resistance on the lightest traffic roads 28

29 Thinlays in Ohio Traffic levels: Traffic Condition: HT (High) Application MED (Medium) LT (Light) UltraLT (Ultralight) ADT: <2500 <500 ADTT: > <250 <25 29

30 Thinlays in Ohio Development: Mix design effort 61 mix designs 6 companies (10 mix design laboratories) Materials from all quarters of the state

31 Thinlays in Ohio Development: Mix designs developed and evaluated: 4 traffic levels (Heavy, Normal, Light, Ultra-Light) 3 asphalt binder grades (PG64-22, PG58-28, PG52-28) Reclaimed Asphalt Pavement (RAP) contents (15%, 20%, 25%)

32 Thinlays in Ohio (ADTT: > 1500) (ADTT: ) (ADT: < 2500 ADTT:< 250) (ADT: < 500 ADTT:< 25) Source: 32

33 Thinlays in Ohio Courtesy of: Flexible Pavements of Ohio 33

34 Thinlay Gradation Sieve Item 404 (1997 CMS) 404 LVT Item 424, Type B Thinlay Item 441, Type 1 1/2 inch /8 inch No No No No No No No Total Binder min. 6.4 min. 6.2 min

35 Thinlays in Ohio Arnold Rd. DarkeCounty Courtesy of: Flexible Pavements of Ohio 35

36 Thinlays in Ohio CLE

37 Thinlays in Ohio ASH-60 PRE

38 Ongoing research: Southern Ohio Low-Volume Experimental Road (SOLVER) VIN centerline miles Existing composite pavement ADT Trucks Phase 1 Phase 2 Thinlays in Ohio 38

39 Thinlays in Ohio SOLVER (VIN-50) Thinlay Placed Fall 2016 (Phase 1) Thickness: ¾ Following plan note Courtesy of: Flexible Pavements of Ohio 39

40 Thinlays in Ohio SOLVER (VIN-50) Thinlay Material Properties Mix Testing Binder Testing Performance Monitoring Noise Friction Texture FWD Pathrunner van (IRI/Rutting/Cracking) 40

41 Acknowledgements Flexible Pavements of Ohio Ohio Department of Transportation Sponsors NCAT and NCAT/MnROAD Dr. R. Buzz Powell, NCAT 41

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