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Inspection Guide

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Inspection GuideRubberized Asphalt Concrete Pilot Training Course5-15.0 Inspection GuideOperation, Production, and Trouble Shooting2AC Plant OperationsPlant operations during RAC mix production are essentially the same as for standard AC mix production. CT 109 requirements apply.Differences Production and monitoring of the asphalt rubber binder for wet process mixes. Plant mixing temperatures of 300-325ºF may be slightly higher than usual.3AR Binder ProductionRequired Documentation AR Binder Design Profile, including Component identification and proportions CRM gradations AR test results showing compliance with specifications Certificates of Compliance for components Asphalt Cement Asphalt Modifier (Extender Oil) Scrap Tire CRM High Natural CRMInspection GuideRubberized Asphalt Concrete Pilot Training Course5-24Asphalt Rubber Blend Design Example Design Profile25 – 7050--46--39Cone Pen @ 25ºC(ASTM D217)52 – 74(125-165ºF)58.560.059.559.559.0R & B Softening Pt., ºC (ASTM D36)18 [email protected] 25ºC (% Rebound)(ASTM D 5329)1500 - 400021002800280028002400Viscosity, cP [email protected] 190ºC1,4403602409045TESTSpec. Limits @ 45 minutes(Caltrans 12/2005)Minutes of Reaction5AR Binder ProductionInspection items Batch sheets or production logs for AR binder that show the amounts (typically by mass) of the components used. Check proportions of:  Asphalt Cement Extender oil Scrap tire CRM High natural CRM6AR Binder ProductionThe AR binder production logs or viscosity testing logs should indicate when the CRM was added. Before adding AR binder to the aggregate: Verify minimum AR interaction time of 45 minutes has elapsed Verify AR binder viscosity meets or exceeds the minimum 1500 cPs requirement at 375ºF Continue to monitor viscosity hourly during RAC mix productionInspection GuideRubberized Asphalt Concrete Pilot Training Course5-37AR Binder ProductionFollow sampling and testing frequency requirements listed in the project special provisions 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 specification compliance.Take additional samples if any changes or discrepancies are observed in any of the materials.8AR Binder ProductionAs 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. 9AR Binder ProductionIf viscosity falls below the minimum limit of 1500 cPs, the AR binder cannot be used to make RAC.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.  The amount of CRM added shall be documented. An additional 45 minute interaction period is required after CRM addition.  Viscosity of the “adjusted” AR binder must comply with viscosity specifications in order to proceed with RAC mix production.Inspection GuideRubberized Asphalt Concrete Pilot Training Course5-410RAC Mix ProductionRequired Documentation RAC Mix Design including: Individual and combined aggregate gradations Results of individual and combined aggregate quality tests Aggregate source(s) and blend proportions Theoretical maximum specific gravity/density Design AR binder content Design air voids content Design VMA Hveem Stability11RAC Mix Production Verify AC plant complies with CT 109 requirements. Check aggregate bins. Sample aggregate cold feed or hot bins as appropriate and verify gradation. Test Sand Equivalent as required. Verify RAC mixing and discharge temperatures. Visually inspect the RAC mix in the haul truck before it leaves the plant. Sample and test RAC mix according to the project special provisions. Tests include gradation, AR binder content, maximum theoretical specific gravity, lab-compacted air voids, and Hveem stability.12RAC Mix Production Verify that haul trucks are tarped. Maintain inspector's log of pertinent information, including but not limited to:  List of samples obtained Plant test results (aggregates and mix)  Quantities of AR binder and RAC mix Binder production temperatures and viscosity measurements, etc. Other required informationInspection GuideRubberized Asphalt Concrete Pilot Training Course5-513RAC Mix Production May use Caltrans Form CEM-3501, AC Production/Placement Checklist modified for RAC See handout example14Inspection at Paving SiteBefore Overlay Placement: Verify surface preparation is complete Cracks treated or sealed? Damaged areas repaired? Milling properly completed (if applicable)? Surface clean and swept? Tack coat properly applied? Verify ambient and pavement temperatures are at least 55ºF and rising15Inspection at Paving Site Equipment Verify that paver and rollers meet size requirements, are in good working condition, and qualified operators are on-site Verify sufficient steel-tired rollers are available for breakdown and intermediate compaction.  Breakdown rollers must have vibratory capability Delivery method: Do not use windrows if ambient temperature is marginally cold.Inspection GuideRubberized Asphalt Concrete Pilot Training Course5-616Inspection at Paving SiteCaltrans requirements for RAC-G, ambient temperature <65ºF: RAC-G spread temperature 290-325ºF Minimum temperature for breakdown rolling is 280ºF Vibratory mode is required for RAC-G breakdown Complete breakdown before RAC mat temperature drops below 260ºF17Inspection at Paving Site Less stringent for ambient temperature ≥65ºF Other jurisdictions recommend minimum 290ºF for breakdown rolling or completion thereof Compaction requirements will be implemented for RAC-G mixes in the future, with acceptance based on cores18Inspection at Paving SiteCaltrans placement temperature requirements for RAC-O and RAC-O-HB ambient temperature <65ºF are the same as for RAC-G. Other jurisdictions do not recommend placing RAC-O at temperatures <65ºF.For open-graded RAC mixes, use static mode


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