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Forensic Analysis of Asphalt Binders For CAPA “Quality Assurance of Asphalt Binders” Ken Grzybowski PRI Asphalt Technologies, Inc. Tampa, Florida. April 2006. PRI. Plant Mixing Difficulty in HMA Compaction Pavement Quality Rutting / Shoving Raveling / Lack of Adhesion Cracking.
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Forensic Analysis of Asphalt BindersForCAPA “Quality Assurance of Asphalt Binders”Ken GrzybowskiPRI Asphalt Technologies, Inc.Tampa, Florida April 2006
PRI Plant Mixing Difficulty in HMA Compaction Pavement Quality Rutting / Shoving Raveling / Lack of Adhesion Cracking Forensics - Where Used
PRI Where to Check – The ObviousBinder Storage Tanks Temperature Correct?Thermometers working, calibrated? “Heater” and recirculation pumps working? Right Product in Tank? Samples Retained (makes life much easier)? Sample representative? PLANT MIXING(‘binder does not coat’)
PRI Where to Check – The ObviousStockpiles & JMF Aggregates Dry?Feed Rates Proper?Asphalt Binder JMF Aggregate Blend Lime (if used) Asphalt Binder % per JMF? PLANT MIXING(‘binder does not coat’)
PRI Where to Check – Not So ObviousAsphalt TankLow Temperature(higher viscosity = reduced flow) Heating Coils / Fire Tubes ‘Coked’‘Buried’ (common w/ some GTR blends) High Temperature (lower viscosity = ‘higher’ flow & less weight) Recirculation pumps / agitators not working Temperature controls not properly workingSensor PLANT MIXING(‘binder does not coat’)
PRI Where to Check – Not So ObviousAsphalt TankAsphalts will layer (larger tanks more susceptible)Different grades or sources = different SG’s possiblyHeat Transfer Fluid LeakYields a more fluid binder / lower viscosity PLANT MIXING(‘binder does not coat’)
PRI Where to Check – Not So ObviousAsphalt TankOverheatingTank open to atmosphereVolatiles loss = stiffer binder / higher viscosity(a prime reason most binders age in-the-tank) Tank closedAsphalt ‘cracks’ = more fluid binder / lower viscosity PLANT MIXING(‘binder does not coat’)
PRI Where to Check – Not So ObviousPoor Coating VisibleAggregate DryingMoist aggregate Easy Solution – first place to look Burner FuelKnow the fuel (purchase specs?) Incomplete combustion Does not take much – difficult to detect Fuel Leak Does not take much – difficult to detect PLANT MIXING(‘binder does not coat’)
PRI Poor Density & Workability Incorrect Compaction Process for Mix (obvious) Low HMA Temperatures Wrong Binder Insufficient or Too Much Binder Contaminated Binder Contaminated Mixes Moist aggregate Truck Bed Release (TBR) ‘ends up’ in binder COMPACTION DIFFICULTIES
PRI Rutting / ShovingWrong Binder Too much Binder Contaminated Binder Poor Aggregate Skeleton or JMF Contaminated Mix Moist aggregate Truck Bed Release (TBR) ‘ends up’ in binder PAVEMENT QUALITY
PRI Raveling / Lack of AdhesionIncorrect Binder (anti-strip?) Insufficient Binder Contaminated Binder Improper Aggregate Gradation Contaminated Mix Burner Fuel Moist aggregate Truck Bed Release (TBR) ‘ends up’ in binder Poor Compaction PAVEMENT QUALITY
PRI CrackingInsufficient Binder Contaminated Binder Improper Aggregate Gradation Contaminated Mix Burner Fuel Moist aggregate Truck Bed Release (TBR) ‘ends up’ in binder Pavement System Design and Architecture PAVEMENT QUALITY
PRI Define the ProblemNature and extent (what’s changed?) People Process Materials Application Combinations of the above Forensic Basics (where to start)
PRI Most (but not always) problem originates with peopleSimple mistakes / lack of attention to details Must admit you have a problem Ask obvious questions of those involved Saves time, money and wasted effort Align your facts and information Learn from previous mistakes (remembered?) Mistakes tend to repeat Forensic Basics (what you already know)
PRI Tank or Purchased Products Compare to Specifications PG, Pen or Viscosity AASHTO, ASTM or Agency Specification Evaluate for Composition Polymer Type & Content (SBS, SBR, EVA, Others) Additives (Acid, Bases, A-S’s, Cross-Linkers, etc) Contaminates (Fuel Oils, Used Motor Oil, Distillates, etc.) Forensics – Our Binder Capability
PRI Plant / Loose Hot MixExtract and Recover Binder & AggregateRequires experience and knowledge Extraction & recovery process may change binder properties Compare recovered binder to Specifications Laboratory must have ‘complete’ capability PG, Pen or Viscosity (AASHTO, ASTM or Agency Specification) Evaluate for Composition Polymer Type & ContentAdditives (diluents, etc)Contaminates (burner fuel, moisture, etc.) Forensics – Our Binder Capability
PRI Sample / Core Pavement PlanSufficient & representative samples to evaluate and assess per plan Agencies may define Use industry accepted practices Documented Plan Sample labels, weights, measures & photos Lift / layer labels, weights, measures & photos Forensics – Pavement Analysis
PRI Two Step Evaluation Process1st Step (may option to jump to 2nd Step) ‘Non-Destructive’ Testing focused at problem(are there specs for comparison??) Performance Properties, a few examples Resilient Modulus, IDT, Permeability Physical Properties Volumetrics Forensics – Pavement Analysis
PRI 2nd Step, - Destructive TestingExtract and Recover Binder & Aggregates Requires experience and knowledgeExtraction & recovery process may change binder properties Reflux Extraction = ‘bad’ Solvent selection critical (may change binder properties) Recovery by D5404 or D1856 (Abson) are musts PreferredASTM D2172, Centrifuge preferred w/ toluene ASTM D5404, Roto-Vap Recovery Forensics – Pavement Capability
PRI Recovered Binder AnalysisCompare recovered binder to specifications & requirements, concentrate on defined problem PG, Pen or Viscosity, Other or select properties AASHTO, ASTM or Agency Specifications Evaluate for Composition (analytical techniques) Polymer Type & Content Additives (diluents, A-S’s, etc) Contaminates (burner fuel, distillates, moisture, etc.) Forensics – Pavement Capability
PRI Recovered AggregatesInvestigate for specification compliance Consensus properties JMF gradation Contaminates Forensics – Pavement Analysis
PRI Determine the ‘story’Each bit of data fits in (sum of parts = whole) Materials JMF Architecture & Specifications Construction Performance Properties Forensics – Pavement Analysis
PRI What we can determineBinder’s specification compliance As neat binder or recovered from loose or compacted HMA’s (field aged) Binder’s Composition Type and quantity of polymer, additive or other To a degree if binder was straight run or ‘engineered’ Presence of Contaminates Today’s Capabilities
PRI What we can determineMix Design Compliance Conventional (Marshall, Hveem) and Superpave Mix Performance Properties On lab and field samples On lab aged specimens (emerging technology) Aggregate Properties Pavement Architectural Soundness Today’s Capabilities
PRI Conflict Resolution Problem Solve Improve Materials and Process Improve Performance Advance the Technology Why?
PRI Conflict Resolution No Specifications Empirical or Subjective Specifications Prescriptive Specifications Reluctance to changeInvestigation Cost vs. Job / Problem ValuePlace the Blame Issues
PRI Problem Solve, Improve Materials & Process, or Performance Low Priority, unless! Production or cost impacted Issues
PRI Questions
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