2016 Public Works Officers Institute Rubberized Asphalt Concrete (RAC) Theron Roschen, PE Interwest Consulting

Transcription

1 2016 Public Works Officers Institute Rubberized Asphalt Concrete (RAC) Theron Roschen, PE Interwest Consulting With assistance from: The California Department of Resources Recycling and Recovery (CalRecycle)

2 NO COST TECHNOLOGY TRANSFER THROUGH Seminars Field Assistance Technical Reviews Guidelines Grant Assistance

3 Why choose asphalt rubber? Less maintenance Higher binder without rutting Resistance to reflective & fatigue cracking Established life cycle cost-effectiveness Can be used in reduced thickness Proven alternative to costly reconstruction Quieter pavements Green

4 California Scrap Tire Overview Generates million scrap tires/year $1.75 per tire collected from CalRecycle Grants

5 Asphalt-Rubber as defined by ASTM D8-88 Asphalt-Rubber is a blend of asphalt cement, reclaimed tire rubber and certain additives, in which the rubber component is at least 15% by weight of the total blend and has reacted in the hot asphalt cement sufficiently to cause swelling of the rubber particles.

6 Tire rubber completely digested Refined for 16 hours, under pressure and temperature Non proprietary Meets PG grading system Material comes ready to use upon arrival Polymers may be added Greenbook TR Meets CalRecycle Grants

7 Viscosity is what defines Asphalt-Rubber Binder Asphalt-Rubber 1,500 to 2,500 Centipoises At 375 Extremely Viscous Rubberized Asphalt Terminal Blend 300 to 600 Centipoises At 325

8 Aggregate Gradation Comparison Open Graded Gap Graded Dense Graded

9 Granulation 2 Inch Chips Reduced to ¾ Inch While Separating Steel

10 Granulation ¾ Inch Reduced to 3/8 Inch While Separating Fabric and Steel

11 Finish Product and Bagging

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13 Ground tire rubber in 2,000 pound Supersacks

14 Rubber is fed from the weigh hopper into a high shear mixer.

15 liquid asphalt and modifier at 375 to 425 F

16 HMA vs. RAC RAC Presentation West Covina January 27,

17 Design of Asphalt Rubber Pavements Uses a deflection based design method Up to 50 % reduction in thickness compared to conventional AC design thickness to retard reflective cracking Over 1000 reduced thickness projects KLEINFELDER Mike Robinson Lincoln / Rocklin PMAR March 5,

18 Heavy Vehicle Simulator UC Davis

19 Heavy Vehicle Simulator UC Davis

20 Page 20 Agenda

21 3 Conv. AC 1 1/2 ARHM 1 ARHM

22 Performance in Indio, CA

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24 StreetSaver PCI Curve 2014 Pavement Condition Index (PCI) Asphalt Rubber vs. Conventional for Arterial Streets About 300 data points Extends About 7 Years Conventional HMA Family Curve New RAC Family Curve Age of Pavement (Year)

25 SHOULD BE A MINIMUM OF 315 F LEAVING PLANT Temp of ARHM-GG

26 Virgin Asphalt Temp: Reaction Temperature: Mix Plant: 1 st Breakdown: All compaction: Ambient/Surface Temp: >375 F F F >280 F >250 F >55 F RAC Presentation West Covina January 27,

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28 Multicool 55 o, 5 mph wind, 2 less than 10 minutes RAC Presentation West Covina January 27,

29 65 o Ambient & Surface, 5 mph wind Temp ( o F) " 1.5" 1.2" 1" Minutes RAC Presentation West Covina January 27,

30 But it s not just cooling RAC Presentation West Covina January 27,

31 But it s not just cooling Roller Not enough densification here Too thin and too cold here RAC Presentation West Covina January 27,

32 Surface Preparation Cracks filled in advance? R & R obvious subgrade failures Leveling course Remove thermoplastic markings Mill conforms at curb and end match Sweep / power wash

33 Cost Factors When AR is in production the plant can not make conventional Haul distance and ambient temperatures Traffic control for cooling time KLEINFELDER Mike Robinson Lincoln / Rocklin PMAR March 5,

34 Contractor s Cost Issues Small Projects = LARGE UNIT COSTS!! Expensive move-in Agencies can save $$ with coordination/procurement Follow Caltrans Bidding in the Winter will allow efficient scheduling for the upcoming season Be flexible KLEINFELDER Mike Robinson Lincoln / Rocklin PMAR March 5,

35 + 5% Proposal, Dist. Director Exception 2/15

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37 RAC pricing can be volatile based on many factors: Cost of Oil Tonnage Bid Blender Availability Geographic Location Urban vs. Rural Locations Contractor Familiarity Proximity of Crumb Plants Haul Distance to Site Seasonal Temps Terminal Blend RAC vs. Field Blend RAC

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39 310 Caltrans and local agency projects were analyzed: Average all projects - RAC projects cost 15.5% higher. ($95.40 per ton vs. $80.55 per ton) The differential RAC vs. conventional trending down by 29% over past 3-years Average differential between RAC vs. conventional for local agency ~ $20 per ton. Lower tonnage projects (3,000 to 7,000 tons), average cost increase 14.5% higher than a 12,000 ton project.

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43 Application 375 o F to 400 o F 0.60 to 0.65 gallons/sy

44 (Hot Pre-Coated Aggregate)

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46 A fog seal can reduce chip loss Slurry seal makes a smoother surface

47 2010 City of Roseville Double Chip 3/8 warm-mix AR 1/8 terminal rubber (TR) AR 340 o F (60 o less), 0.6 G/SY, 30lbs/SY TR 350 o F, 0.25 G/SY, 9lbs/SY Pre-coated, Pre-heated $5.50 per SY

48 Double Chip Seal Two Layer System

49 City of Roseville Double Chip 25 year little or no maintenance 3 AC on 4 AB Collector and Residential

50 City of Roseville Double Chip Application of AR Warm-mix and 3/8 Chip

51 City of Roseville Double Chip Application of TR 1/8 Chip

52 SAMI - Stress Absorbing Membrane Interlayer Pre-existing Pavement Also known as a Two Layer System AC or ARC Overlay KLEINFELDER Mike Robinson Lincoln / Rocklin PMAR March 5,

53 Rubberized Asphalt Concrete Grants Next Cycle Fall

54 Regional Grants Two or more eligible applicants Guaranteed Reimbursed at program maximum ($10 per ton, $0.50 per SY chip seal) regardless of # prior grants $400,000 max grant, $250,000 per agency Priority consideration over other applicants Does not count toward future grant considerations

55 Regional Grant Benefits Larger economy of scale for all participants Opening RAC market to smaller agencies with smaller quantities Allowing termed-out or lower grant reimbursement rate to participate at a higher rate Create future partnerships and share experiences

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57 Questions? Theron Roschen, PE Interwest Consulting Group Questions? Questions? Page 57