1 USE OF ASPHALT RUBBER IN PAVEMENTS Construction Inspection Overview Technology Transfer Series ARHM- 105 Webinar

2 CONSTRUCTION INSPECTOR ROLES COMPOSITION OF ARHM MIX DESIGN & CERTIFICATES INSPECTION AT THE PLANT JOB SITE INSPECTIONS TROUBLESHOOTING & SUMMARY PRESENTATION TOPICS

3 CONSTRUCTION INSPECTOR ROLES 1 Serve as link between the designer and the contractor Verify that work conforms to plans and specifications 2

4 Previously AR-4000 Now PG or PG Scrap Tire 75% High Natural Rubber25% COMPOSITION OF ARHM 1.Gap Graded Aggregate 2.Asphalt Rubber Binder Paving Asphalt - 80% Crumb Rubber - 20%

5 AGGREGATE GRADATIONS A gap-graded mix is defined as continuously graded with 1 or 2 finer sizes missing Sieve Size "C2" 1/2" dense graded "ARHM-GG-C" 1/2" gap-graded Min. - Max.(Mid Pt)Min. - Max.(Mid Pt) 19.0 mm (3/4 in.) mm (1/2 in.)95-100(97.5)90-100(95.0) 9.5 mm (3/8 in.)72-88(80.0)78-92(85.0) 4.5 mm (No. 4)46-60(53.0)28-42(35.0) 2.36 mm (No. 8)28-42(35.0)15-25(20.0) 600 µm (No. 30)15-27(21.0)5-15(10.0) 300 µm (No. 50)10-20(15.0) 75 µm (No. 200)2-7(4.5)2-7(4.5)

6 CRM GRADATION REQUIREMENTS Greenbook Table (A) Sieve Size Scrap Tire CRM Percent passing High Natural CRM Percent passing 2.36 mm (No. 8) mm (No.10) mm (No. 16) µm (No. 30) µm (No. 50) µm (No µm (No. 200)---0-1

7 CRUMB RUBBER SCRAP TIRE 1/16” +/- in Size HIGH NATURAL RUBBER 1/32” +/- in Size

8 MIX DESIGN & CERTIFICATES Submitted by the Contractor Per Greenbook (203-11), or local specifications Hveem Method (Modified CA Test Method 367)

9 PROPERTIES OF ARHM MIX DESIGN Air Voids 3% - 6% per Greenbook Suggest Maximum 5% Voids in Mineral Aggregates – VMA 18% Minimum to 23% Maximum Asphalt Rubber Binder Content Greenbook Minimum 7.5% –Max 8.7% Combined Aggregate Gradation Stability (23 Min.)

10 GREENBOOK MIX DESIGN TABLE (A) REQUIREMENTS FOR ARHM-GG SIEVE SIZE CLASS ARHM-GG-B Min. - Max. ARHM-GG-C Min. - Max. ARHM-GG-D Min. - Max. 25 mm (1 in.) mm (3/4 in.) mm (1/2 in.) mm (3/8 in.) mm (No. 4) mm (No. 8) µm (No. 30) µm (No. 200) % Asphalt Rubber Binder by Weight of Dry Aggregate ∗ Air Voids % Calif. Test Stabilometer Value Min. Calif. Test 304 and Voids in Mineral Agg. Percent Min.18 * Once the percent asphalt rubber binder is determined by the mix design, the production tolerance shall be ±0.5 % as determined by California Test Method 362, 379, or 382.

11 HVEEM MIX DESIGN CRITERIA Modified, Step 2 not used Caltrans Mods Pending

12 INSPECTION AT THE PLANT 1.Scales 2.Combined Grading 3.Proportioning Crumb Rubber Paving Asphalt

13 INSPECTION AT THE PLANT Plant operations during ARHM mix production are essentially the same as for standard AC mix production. CT 109 requirements apply. Production and monitoring of the asphalt rubber binder for wet process mixes Plant mixing temperatures of ºF may be slightly higher than usual Differences

14 CT PLANT CERTIFICATION

15 SAMPLING COMBINED AGGREGATE DRUM PLANT BELT SAMPLE

16 MIXING OF PAVING ASPHALT AND CRM BLENDER CONTROL PANEL CRM PROPORTIONING: 1. SCRAP TIRES (3 BAGS) 2. HIGH NATURAL (1 BAG) BLENDING PAVING ASPHALT & CRM MIXING/ REACTION TANK

17 INSPECTION AT THE PLANT Continued Viscosity of asphalt rubber binder.. Temperature of ARHM Samples of CRM, paving asphalt, asphalt rubber binder, aggregates, and ARHM

18 INSPECTION AT THE PLANT Continued Required Documentation: Component identification and proportions CRM gradations AR test results showing compliance with specifications Asphalt Cement Asphalt Modifier (Extender Oil) Scrap Tire CRM High Natural CRM Asphalt Rubber Binder Production AR Binder Design Profile Certificates of Compliance

19 AR BINDER PRODUCTION TEST Minutes of ReactionSpec. 45 minutes 2006 Greenbook ,440 Viscosity, Haake- 191ºC (375ºF) Centipoise ºC (77ºF) (% Rebound) (ASTM D 5329) Minimum R & B Softening Pt., ºC (ºF) ( ASTM D36) – 74 ( ºF) Cone 25ºC (ASTM D217) – 70 Asphalt Rubber Binder Design Profile

20 AR BINDER PRODUCTION Continued Batch sheets or production logs for AR binder that show the amounts (typically by mass) of the components used Asphalt Cement Extender oil Scrap tire CRM High natural CRM Inspection Items Check Proportions

21 AR BINDER PRODUCTION Continued 1. Verify minimum AR interaction time of 45 minutes has elapsed 2. Verify AR binder viscosity meets or exceeds the minimum 1500 cPs requirement at 375ºF 3. Continue to monitor viscosity hourly during RAC mix production The AR binder production logs or viscosity testing logs should show when the CRM was added. Before adding AR Binder to the Aggregate

22 HAAKE FIELD VISCOSITY TEST 1500 – 4000 Centipoise at 375 o F Haake Viscometer

23 AR BINDER PRODUCTION Continued Follow sampling and testing frequency requirements listed in the specifications for AR binder and individual components. Typically, at least one one-gallon sample should be obtained from each batch of binder produced. Of these, some samples would be randomly selected and tested for compliance. Take additional samples if any changes or discrepancies are observed in any of the materials.

24 AR BINDER PRODUCTION Continued As long as interaction time and viscosity meet or exceed minimum requirements, the AR binder may be added to the aggregate, even if viscosity differs from values shown in the design profile. The design profile serves as a guide, not as a specification. If viscosity during production differs from design profile by 400 cPs or more for corresponding interaction interval, obtain a binder sample for compliance testing.

25 AR BINDER PRODUCTION Continued If viscosity falls below the minimum limit of 1500 cPs, the AR binder cannot be used for RAC. 1. The amount of CRM added shall be documented 2. An additional 45 minute interaction period is required after CRM addition. 3. Viscosity of the “adjusted” AR binder must comply with viscosity specifications in order to proceed with ARHM mix production To restore viscosity, the AR binder producer may add up to 10% more CRM (using the design ratios of scrap tire and high natural CRM) by total binder mass.

26 ARHM MIX - Required Documentation ARHM Mix Design including Individual and combined aggregate gradations Results of individual & combined aggregate tests Aggregate source (s) and blend proportions Theoretical Maximum Specific Gravity/Density Design AR Binder content Design Air voids content Design VMA Hveem Stability

27 Required Documentation Continued ARHM Aggregate Individual and combined aggregate gradations Verify AC plant complies with CT 109 requirements Check aggregate bins Sample aggregate cold feed Hot bins as appropriate and verify gradation Test Sand Equivalent as required

28 Required Documentation Continued ARHM Mix Verify ARHM mixing and discharge temperatures Visually inspect mix in haul truck before leaving plant Gradation AR Binder content Maximum Theoretical Specific Gravity Lab-compacted Air Voids Hveem Stability ARHM Mix Sample & Tests

29 Required Documentation Continued Verify that haul trucks are tarped. Maintain inspector's log of pertinent information 1.List of samples obtained 2.Plant test results (aggregates & mix) 3.Quantities of AR binder and ARHM mix 4.Binder production temps & viscosity measurements 5.Other: problems, items of note, events

30 TEMPERATURE OF ARHM SHOULD BE A MINIMUM OF F LEAVING PLANT

31 SAMPLES Paving Asphalt Asphalt Rubber Binder Crumb Rubber Samples ARHM

32 TESTING FOR BINDER CONTENT IGNITION OVEN INCOMPLETE IGNITION

33 JOB SITE INSPECTION PRIOR TO PAVING Pre-Construction Meeting Approved mix design Surface preparation Delivery method Rate of delivery Equipment in good working order Number and type of rollers ( ) Other Issues (Refer to A-R Design Guide) Ambient and surface temperatures (>50 º F) Temperatures > 60ºF are more effective in achieving desirable compaction

34 Cold milling complete? Surface cleaned? Tack properly applied? Paving grade asphalt preferred Cracks over ¼ -inch wide sealed? Caution: Do not over-apply sealant to avoid creating “fat spots” in the new ARHM surface during compaction. R&R distressed areas (dig-outs) complete? JOB SITE INSPECTION DURING PAVING

35 “…a tack coat…shall be uniformly applied upon the existing pavement…” ( )

36 JOB SITE INSPECTION DURING PAVING Automatic screed control working? Temperature of ARHM in trucks and hopper TEMPERATURE IS CRITICAL FOR ARHM Condition of the ARHM (Smoking, stiff, shiny, slumped, segregated) Delivery rate of ARHM – appropriate? If temperatures are marginally cold, do not windrow Paving machine moving at a uniform rate?

37 Drive wheel forward Low side to high side Hot side to cold side Direction changes Sequence: 1) Transverse joints 2) Longitudinal joints Breakdown passes (vibrator on) JOB SITE INSPECTION DURING PAVING Rolling techniques

38 JOB SITE INSPECTION DURING PAVING Breakdown may require more than one coverage Need to get ≈ 95% of required compaction during breakdown to achieve target compaction requirements Temperature of mat at initiation of breakdown rolling (> 290oF) Minimize handwork, raking and luting

39 JOB SITE INSPECTION DURING PAVING Paving machine moving at a uniform rate? Collect load tickets and track tonnage placed Measure placement thickness and calculate yield Observe coordination between ARHM delivery and placement Record if trucks or paver are waiting Note any rejected loads of ARHM Observe delivery operations - are good practices being used? During ARHM placement

40 JOB SITE INSPECTION DURING PAVING Record if windrows are used. Monitor ARHM temperatures at spread (per Greenbook 290/300 to 330ºF) and during breakdown (290ºF) and intermediate compaction. Observe paver operations – note discrepancies from good practice that might impact quality of joints or ride (smoothness). Joints at proper locations? Observe raking, luting, handwork. Broadcasting of excess mix or over-raking will damage the appearance of the finished pavement.

41 JOB SITE INSPECTION DURING PAVING Observe compaction operations – note discrepancies from good practice that might impact in-place density Breakdown roller(s) following immediately behind paver? Breakdown roller(s) using vibratory mode? Sufficient breakdown rollers operating to keep up with paver? Intermediate static roller(s) keeping up? Finish rollers effective?

42 “The asphalt concrete as delivered shall be deposited directly into the hopper of the spreading and finishing machine.” ( )

43 “With the approval of the Engineer, the Contractor may deposit…into a uniformly sized windrow, then pick up the material and convey it …with loading equipment provided.” ( , 2006 Greenbook)

44 “ The machine shall be equipped with a suitable full-width compacting screed…” ( ) Fully Automatic Screed Control Device

45 “…vibratory rollers using the vibratory mode shall be used for initial break down rolling. The initial coverage…shall commence before the…temperature falls below…(280/290  F)” ( )

46 “Pnuematic rollers shall not be used.”

47 “At the option of the Engineer, when traffic conditions warrant, a rock dust or sand blotter may be required to avoid tracking.” ( ) Casting from the side

48 “When the…pavement has cooled to below…(150  F), the …blotter may not be required.” ( ) Casting from the side

49 JOB SITE INSPECTION AFTER PAVING Check the appearance of the finished surface for roller marks, scuffs, gouges, or other irregularities Check smoothness as required in project special provisions Visually evaluate quality of paving joints and identify any areas that may need to be sealed Identify core locations for compaction acceptance if applicable

50 Lunch Time – ARHM at rest

51 TROUBLESHOOTING If any type of ARHM mix problem is suspected, obtain samples immediately and test for compliance with project special provisions Log full description of problem and related activities and report to the Engineer

52 TROUBLESHOOTING Segregation: Particle size segregation may be difficult to ID in coarse graded ARHM-GG mixtures. May appear segregated even if not, due to small percentage of fines included. When in doubt, sample ID affected truckloads and corresponding placement areas for info Size segregation is often accompanied by temperature segregation Possible Problems to Watch For:

53 TROUBLESHOOTING Smoke Blue smoke means that the mix is too hot and plant operating temperature needs to be adjusted White smoke is steam - too much moisture in the mix. May make mix tender and interfere with compaction. Aggregate needs to be dried longer before mixing with the AR binder

54 TROUBLESHOOTING Stiff appearance: Too cool or possibly somewhat low AR binder content. Check temperature and get a mix sample for further testing if needed. Dull, flat appearance: Low AR binder content and/or excessive fines. Localized areas may indicate insufficient mixing or segregation. Get sample and test for gradation and AR binder content.

55 TROUBLESHOOTING Typically indicates high AR binder content. Open-graded mixes may look this way and still meet specifications Old descriptive term is “wormy” – mix seems to almost crawl while watched Some complying ARHM-GG mixes may also be wormy Visually check for binder drain down in the haul truck bed, sample and test for AR binder content and gradation Slumped and Shiny Appearance

56 SUMMARY Changes in the plant inspector’s duties due to ARHM production are limited to: Monitoring AR binder production and viscosity results Sampling AR binder and individual component materials for verification and acceptance Changes to field inspector’s duties are very minor, primarily related to monitoring ARHM temperature and compaction operations

57 TYPICAL ASPHALT PAVING FAILURES Low binder content Overheated Mix Absorptive Aggregate Weathered Or Dry Surface

58 TYPICAL ASPHALT PAVING FAILURES Too much binder Too much tack coat Too many aggregate fines Bleeding And Instability Rounded aggregates Low air void contents

59 Lean or overheated mix Low density/ under compaction Raveling TYPICAL ASPHALT PAVING FAILURES

60 Existing street not clean Improper tack coat Slipping TYPICAL ASPHALT PAVING FAILURES

61 YOU ARE THE KEY QUALITY CONSTRUCTION THROUGH QUALITY INSPECTION