Evaluation of Mechanistic Properties of Hot-Mix Asphalt Containing Recycled Shingles (RAS)

Transcription

1 Evaluatio of Mechaistic Properties of Hot-Mix Asphalt Cotaiig Recycled Shigles (RAS) NESMEA Coferece - October 19, 2016 Michael Maher Ludomir Uzarowski

2 Gree Pavemet Techologies - Overview Gree pavemet techologies iclude iovative pavemet materials, as well as pavemet rehabilitatio methodologies O the pavemet rehabilitatio side, gree techologies have icluded pavemet recyclig such as: Hot i-place recyclig Cold i-place recyclig Full depth reclamatio CIREAM Stabilizatio of soils Cocrete pavemet rubbilizatio Cocrete pavemet restoratio December 2,

3 Itroductio Gree pavemet techologies have bee successfully used for more tha 30 years Materials RAP ad RAS i HMA Crumb rubber i HMA Recycled cocrete as aggregates Steel slag, crushed glass ad ceramic as HMA aggregates December 2,

4 Itroductio It is geerally agreed that the mai purpose for the use of gree techologies is to make pavemets more sustaiable i terms of: Ecoomics: cheaper material sources; i situ vs. plat materials; use of waste ad by-products Eviromet: reduced use of scarce resources; lower GHG; lower eergy usage; less truckig; less waste geeratio Social: faster costructio/less disruptio; more public moey for other projects December 2,

5 Pavemet Sustaiability Effectively desiged sustaiable pavemets should aim to: Miimize the use of o-reewable atural resources Reduce eergy ad fuel cosumptio durig costructio ad operatio Miimize GHG emissios Reduce waste geeratio Reduce frequecy ad extet of maiteace itervetios Improve health ad safety ad reduce risk Lower cost Esure a high level of user comfort ad safety Provide log term value for moey December 2,

6 Recycled Asphalt Shigles (RAS) Roofig shigles cosist of: High quality fie agular aggregate ad filler (50-60%) Asphalt cemet (20-30%) Fibers (5-15%) Source Post-maufactured PG High Temp Grade: Post-cosumer PG High Temp Grade:

7 Process Idustrial grider Typically 100% passig from 12.5 mm (1/2 ich) Fier grid performs better Sortig by had eeded for QC o supply to remove ails, wood, paper, etc. Image source: Williams et al,

8 Itroductio 10 millio toes of post cosumer shigles go to ladfill i the U.S. every year Represets 3% of muicipal waste ~20 states have specificatios for use of RAS i HMA Typically allow 5% post-maufactured or 3% post-cosumer i asphalt mixes Refereces AASHTO MP 23-14: Stadard Specificatio for Reclaimed Asphalt Shigles i Asphalt Mixtures AASHTO PP 78-14: Stadard Practice for Desig Cosideratios Whe Usig Reclaimed Asphalt Shigles (RAS) i Asphalt Mixtures

9 Evaluatio

10 Project Objectives Evaluate the feasibility of addig RAS ad RAP to asphalt mixes used i Vacouver 80,000 tos of shigles to ladfills each year Sustaiability aalysis Evaluate laboratory performace Determie method of performace evaluatio Select mix types Additio should ot compromise pavemet performace Determiig the optimum amout of RAS ad RAP Performace Cost effectiveess

11 Mix Evaluatio Laboratory performace evaluatio Mechaistic properties a) Ruttig resistace b) Dyamic modulus c) Resiliet modulus d) Susceptibility to low temperature crackig e) Fatigue edurace Asphalt cemet testig PG grade verificatio

12 Mix Additives Post-cosumer shigles used RAS groud to 6-7 mm chips RAS added to mixes by weight of mix Rejuveator (Cycloge) used to softe the asphalt cemet i mixes cotaiig recyclables Covetioal City of Vacouver bider course mix used with PG December 2,

13 Groud RAS Gradatio Sieve Size (mm) % Passig December 2,

14 Trial Mixes Mix RAS (%) RAP (%) Rejuveator* (%) B

15 Laboratory Evaluatio Procedures

16 APA Testig Asphalt Pavemet Aalyzer (APA) AASHTO TP Loaded wheel rus across sample o iflated rubber hose Samples tested i air at 58 C (136ºF) Wheel rus for 8,000 cycles (oe cycle is two passes)

17 Observed Ruttig December 2,

18 Acceptable limit at 8,000 cycles for high volume roads APA Results

19 Ruttig Resistace Number of Cycles Average Permaet Deformatio i APA (mm) Mix 1 Mix 2 Mix 2B Mix 3 Mix 4 Mix 5 Mix 6 8,

20 Fidigs From APA Best ruttig resistace for Mix 1, 2B, 4 ad 6 Mixes 2 ad 5 had most deformatio idicatig substatial affect of rejuveator with lower amout of RAS Mixes 4 ad 6 showed that whe rejuveator was added, ruttig resistace could be brought to origial level by addig eough RAS (i.e. 5%) December 2,

21 Dyamic Modulus Testig Evaluates modulus of mix uder various temperatures ad traffic loads 14, 39, 70, 99 ad 129 F 25, 10, 5, 1, 0.5 ad 0.1 Hz AASHTO TP Higher frequecies = fast movig traffic Lower frequecies = slow movig or static traffic Modulus is a fuctio of the stress ad strai experieced December 2,

22 Dyamic Modulus Results

23 Dyamic Modulus Results Test Temperature: 70 F Dyamic Modulus - MPa Frequecy (Hz) Mix ID 1 2 2B ,400 5,000 8,900 4,400 5,200 4,600 7, ,100 4,400 7,700 4,100 4,800 3,900 6, ,000 3,800 6,700 3,600 4,200 3,400 5, ,400 2,600 4,700 2,500 2,900 2,300 3, ,000 2,300 4,100 2,300 2,600 2,100 3, ,200 1,800 3,000 1,800 2,100 1,700 2,600

24 Dyamic Modulus Results Test Temperature: 129 F Dyamic Modulus - MPa Frequecy Mix ID (Hz) 1 2 2B ,

25 Dyamic Modulus Mixes 1, 2B ad 6 had the highest dyamic modulus values Mixes 2, 3 ad 5 exhibited the lowest modulus values Whe rejuveator was added to mixes their modulus dropped sigificatly Whe 5% RAS was added to the mixes (alog with rejuveator) the mix modulus icreased agai, close to the origial level

26 Resiliet Modulus Testig Idirect Tesile Stregth (IDT) testig carried out to determie loadig for resiliet modulus ASTM D All mixes were tested at 18 kn load Resiliet modulus ivolves loadig samples alog the vertical diametral plae ASTM D

27 Resiliet Modulus Testig Both vertical ad horizotal movemet were measured Each sample was tested twice with a 90 rotatio i betwee

28 Resiliet Modulus Results Resiliet Modulus (MPa) 4,000 3,500 3,000 2,500 2,000 1,500 1,000 Resiliet Modulus Mix 1 Mix 2 Mix 2B Mix 3 Mix 4 Mix 5 Mix 6 Mix

29 Resiliet Modulus Treds Mixes 1, 2B ad 6 had the highest resiliet modulus values Mixes 2, 3 ad 5 had the lowest resiliet modulus values December 2,

30 TSRST Testig Temperature Stress Restraied Specime Test AASHTO TP10 Used to evaluate low temperature crackig susceptibility

31 TSRST Testig Samples held at costat legth ad cooled at a rate of -50 F/hour As the temperature drops, the sample is maitaied i its origial legth util failure The force is moitored ad recorded

32 TSRST Results Mix # Fracture Stress (MPa) Average Failure Temp ( F) Mix Mix 2B Mix Mix Mix Mix

33 TSRST Results Narrow rage of failure temperatures for all mixes Failure temperatures well below the temperatures i the Vacouver area Rejuveator improved low temperature fracture performace Mixes 4 ad 6 had lower fracture stress resistace All mixes acceptable for this criteria

34 Fatigue Testig Four Poit Flexural Bedig Beam Test ASTM D Cyclical loadig applied at costat strai util stiffess decreases sigificatly Strai 400 µε Temperature 70 F Fatigue life - failure poit whe stiffess decreases by 50% December 2,

35 Fatigue Testig Results Fatigue Life (Cycles) 40,000 35,000 30,000 25,000 20,000 15,000 10,000 5, B Mix Fatigue life Mix 3 the best Other five mixes exhibited similar fatigue edurace

36 Asphalt Cemet Testig PG grade verificatio Virgi asphalt cemet PG Asphalt cemet recovered from three mixes oly Icrease of high (good) ad low (bad) temperature eds i RAS ad RAS/RAP mixes Mix High Temp Rage (ºC) Low Temp Rage (ºC)

37 Aalysis ad Summary

38 Aalysis Mixes 1 ad 2B (covetioal) Good ruttig resistace Highest dyamic ad resiliet modulus Good TSRST results (low temp crackig) Mixes 4 ad 6 Rejuveator ad 5 % RAS Mix 6 also had 15 % RAP Exhibited similar performace to covetioal mixes but lower low temperature (fracture stress) resistace December 2,

39 Aalysis Mixes 3 ad 5 Rejuveator ad 3 % RAS Mix 5 also had 15 % RAP Exhibited larger ruttig depth Lower modulus values Good TSRST results Mix 6 - the optimum for the Vacouver area where low temperature is ot a issue December 2,

40 Premature Crackig with Excess RAS

41 Excessive RAS Crackig of ew bider course that cotaied high percetage of RAS December 2,

42 Excessive RAS Repairs of ew bider course that icorporated high amout of RAS

43 RAS Fibers Recovered i Extractio December 2,

44 Potetial Performace Issues I low temperature areas RAS to be added to HMA with cautio due to potetial for crackig ad ravelig Cosider: % RAS ad %RAP together Usig softer asphalt cemet grade with higher ratios Usig asphalt cemet softeer (rejuveator)

45 Summary 1. 15% RAP does ot egatively affect mix performace 2. Whe rejuveator added to mixes, ruttig resistace ad stiffess dropped 3. Whe 5% RAS was added, mix stiffess ad ruttig resistace icreased to the origial level

46 Summary 4. It is ecessary to achieve a correct ratio betwee rejuveator ad RAS 5. Testig shows that some asphalt mixes cotaiig RAS ca perform similarly to covetioal mixes 6. Optimum mix for Vacouver 15 % RAP 5 % RAS Appropriate amout of rejuveator 7. For Otario (or NE U.S.) this will ot work. 3% RAS cosidered maximum for Otario (without PGAC adjustmet). 8. Appropriate additio of RAS reduces cost ad does ot impair performace

47 Geeral Commets For every 1% of RAS the low temp grade icreases by 1.9ºC For every 1% additio of RAP, low temp icreases by 0.3% Rule of thumb max 20% RAP or 3% RAS before requirig AC grade lowerig This correspods to a 14% bider replacemet with RAS ad a 20% bider replacemet with RAP Study showed mixes with coarser RAS had more crackig tha fier RAS Cost savigs usig RAS ~$7/to at 5% RAS RAS or RAS/RAP bleds improve ruttig resistace but reduce low temperature crackig performace December 2,

48 Questios? Co-author: Michael Maher, Ph.D., P.Eg. Title: Seior Pavemet ad Materials Egieer, Pricipal Phoe: (905) Co-author: Ludomir Uzarowski, Ph.D., P.Eg. Title: Seior Pavemet ad Materials Egieer, Pricipal Phoe: (905) December 2,