Balanced Mix Design (BMD) For Asphalt Mixtures

Balanced Mix Design (BMD) for Asphalt MixturesShane BuchananOldcastle MaterialsSeptember 20, 2016

Discussion Items Need for Balanced Mix Design Define Balanced Mix Design Review FHWA Balanced Mix Design Task Force Efforts Current State Agency PracticeNCHRP Problem Statement DevelopmentTechnical Brief Development on Balanced Mix DesignSHRP2 Peer to Peer Exchange 2016

Need for Balanced Mix Design

What Type Distress Is Occurring?Oldcastle Survey Question:Within the past 5 years, what type of mixperformance related distress has been mostevident in your mixes? 40 companies responding from 30 states Most reported distresses arerelated to mix durability.SHRP2 Peer to Peer Exchange 2016

OPTIMUMPendulum of Asphalt Mix PerformanceDRYWETSHRP2 Peer to Peer Exchange 2016

Binder Content – Design vs. Optimum (There is a difference!) Design and optimum are often usedinterchangeably However, they mean two different things There can be many design binder contents for amix, but only one truly optimum Optimum indicates the best binder contentbased on intended application, performancerequirements/needs, and ultimately economics Goal is to get as close as possible to the trueoptimum for the mixSHRP2 Peer to Peer Exchange 2016

History of Mix Design189019051920s Barber Asphalt Paving Company Asphalt cement 12 to 15% / Sand 70 to 83% / Pulverized carbonite of lime 5 to 15% Clifford Richardson, New York Testing Company Surface sand mix: 100% passing No. 10, 15% passing No. 200, 9 to 14% asphalt Asphaltic concrete for lower layers, VMA terminology used, 2.2% more VMA than current day mixes or 0.9% higher binder content Hubbard Field Method (Charles Hubbard and Frederick Field) Sand asphalt design 30 blow, 6” diameter with compression test (performance) asphaltic concrete design (Modified HF Method)1927 Francis Hveem (Caltrans) Surface area factors used to determine binder content; Hveem stabilometer and cohesionmeter used Air voids not used initially, mixes generally drier relative to others, fatigue cracking an issue1943 Bruce Marshall, Mississippi Highway Department Refined Hubbard Field method, standard compaction energy with drop hammer Initially, only used air voids and VFA, VMA added in 1962; stability and flow utilized1993 Superpave Level 1 (volumetric) Level 2 and 3 (performance based, but never implemented)StabilityStability DurabilityStability DurabilityBINDERCONTENTLOWERSHRP2 Peer to Peer Exchange mix-design-in-north-america-part-2/

Balanced Mix Design Task Force Development History Concern nationally of early age durability relatedperformance issues. Many states have started the process of“performance testing” during mix design and/orproduction to help ensure mix performance. Process has been referred to as a balancedmix design approach. National Pavement Implementation ExecutiveTask Group (PIETG) highlighted BMD as neededfocus areaSHRP2 Peer to Peer Exchange 2016

PIETG The PIETG is focused on the strategic program level challenges and opportunitiesin the deployment of pavement technologies. Focus areas include: Pavement Design and Analysis; Pavement Materials and Quality Assurance; Pavement Surface Characteristics; Construction Technology; Pavement Sustainability; Technical Capacity; and Field Support/Technical Assistance.SHRP2 Peer to Peer Exchange 2016

Pavement Implementation Executive Task Group (PIETG)FHWAJohn BukowskiMaterials Team LeaderChristopher Wagner Pavment and Materials Tech. Srvs. Team LeaderGina AhlstromPavement Design and Analysis Team LeaderJeff WitheePavement Materials EngineerMark SwanlundInfrastructure R&D Program CoordinatorBryan CawleyConstruction Mgmt. Team LeaderStephen GajAsset Mgmt. Team LeaderHari KallaDirector, Office of Asset Mgmt., Pavement & ConstructionFHWAINDUSTRYMike AcottPresidentNAPAAudrey CopelandVP, Engineeering, Tech. and ResearchNAPA (attendee)Gerald VoigtPresident/CEOACPALeif WathneVP, Highways and Federal AffairsACPA (alternate)Jim DuitPresidentDuit Construction Co.Dave HowardPresident/CEOKoss ConstructionRon SinesVP - Asphalt PerformanceOldcastle MaterialsJay WinfordPresidentPrairie Contractors, Inc.DOTsCarlos BracerasExecutive DirectorUtah DOTDave HuftResearch Program Mgr.South Dakota DOTRichard TetreaultDeputy SecretaryVermont Agency of TransportationRussell McMurryCommissionerGeorgia DOTGarrett MooreChief EngineerVirginia DOTACADEMIAPeter TaylorAssociate DirectorIowa State UniversityKevin HallProfessor and HeadUniversity of Arkansas (CE)David NewcombSenior Research ScientistPaul TikalskyDean of EngineeringTexas A&MTransportationInstituteSHRP2Peer to Peer Exchange2016Oklahoma State University

BMD Task Force Formed at September 2015 ETG MTGSHRP2 Peer to Peer Exchange 2016

BMD Task Force MembershipNameDave NewcombJohn HaddockKevin HallLouay MohammadBrian PfeiferBryan EngstromCharlie PanCurt TurgeonDerek Nener-PlanteEliana CarlsonHoward AndersonOak MetcalfeRobert LeeSteven HefelFrank FeeJohn D'AngeloLee GallivanRichard DuvalTim AschenbrenerAndrew HanzChris AbadieErv DukatzGerry HuberShane BuchananAnne HoltRandy WestAffilationTexas Transportation InstitutePurdue UniversityUniversity of ArkansasLouisiana State UniversityIllinois DOTMassachusetts DOTNevada DOTMinnesota DOTMaine DOTConnecticut DOTUtah DOTMontana DOTTexas DOTWisconsin DOTConsultantConsultantConsultantFHWA - Turner FairbankFHWA - DenverMathy ConstructionPine Bluff S&GMathy ConstructionHeritage ResearchOldcastle MaterialsOntario Ministry of encyConsultantConsultantConsultantFHWA AgencyFHWA incial 2 Peer to Peer Exchange 2016westran@auburn.edu

BMD Task Force Goals and Focus Areas Define Balanced Mix Design Determine the current “state ofpractice” of BMD Present approaches/concepts forimmediate use Recommend future needs (potentialresearch) to advance BMD approaches Disseminate informationSHRP2 Peer to Peer Exchange 2016

BMD Task Force Work Items CompletedDefinition of Balanced Mix Design Survey of Agency Current Practice Laboratory Balanced Mix Design Protocols Field Acceptance Protocols Research Problem Statement (RPS) Submitted to AASHTO) Current FHWA Technical Brief on Balanced Mix Design Draft prepared, reviewed and being revisedSHRP2 Peer to Peer Exchange 2016

Balanced Mix Design Definition

Balanced Mix Design Definition “Asphalt mix design using performance tests on appropriatelyconditioned specimens that address multiple modes of distresstaking into consideration mix aging, traffic, climate and locationwithin the pavement structure.” Basically, it consists of designing the mix for an intendedapplication and service requirement.SHRP2 Peer to Peer Exchange 2016

Agency Practices Related to BMD

Agency Approaches – 3 Main Approaches IdentifiedSHRP2 Peer to Peer Exchange 2016

Volumetric Design w/ Performance Verification Volumetric Design w/ PerformanceVerification – basically, it is straightSuperpave with verifying performanceproperties; if the performance is not there,start over and re-design the mix.Volumetric properties would have to fallwithin existing M323 limits. ExampleStates: Illinois, Louisiana, New Jersey, Texas,WisconsinSHRP2 Peer to Peer Exchange 2016

Performance Modified Volumetric Design PerformanceModified VolumetricDesign – the initialdesign bindercontent is selectedusing M323/R35prior to performancetesting; the results ofperformance testingcould ‘modify’ themixture proportions(and/or) adjust thebinder content – andthe final volumetricproperties may beallowed to driftoutside existingM323 limits. ExampleState: CaliforniaSHRP2 Peer to Peer Exchange 2016

Performance Design Performance Design – this involvesconducting a suite of performance tests atvarying binder contents and selecting thedesign binder content from the results.Volumetrics would be determined as the‘last step’ and reported – with norequirements to adhere to the existingM323 limits. Example States: New Jerseyw/ draft approachSHRP2 Peer to Peer Exchange 2016

BMD Basic Example – Volumetric Design w/Performance Verification Texas DOT Volumetric design conductedHamburg Wheel TrackingTest (HWTT) AASHTO T 324Overlay Tester (OT) Tex-248-FThree asphalt bindercontents are used: optimum,optimum 0.5%, andoptimum -0.5%.The HWTT specimens areshort-term conditioned.The OT specimens are longterm conditioned.Within this acceptable range (5.3 to 5.8 percent),the mixture at the selected asphalt content mustmeet the Superpave volumetric criteria.SHRP2 Peer to Peer Exchange 2016

Using Performance Testing to BetterUnderstand Your Mixes Performance spacediagrams show theperformance of a mixrelated to multiple tests Allows the mix designer tovisualize the mixperformance and how toengineer the mix toprovide the desiredperformance Illustrates the impact ofvarying mix factors onperformance.From: Performance-Space Diagram for the Evaluation of High and Low Temperature AsphaltMixture Performance, Buttlar et al, AAPT 2016SHRP2 Peer to Peer Exchange 2016

Need for Production VerificationDesignProductionOptimize Local materials use,recycle, additives,cost, appropriatebinder content Specific site/enduseEstablish Performance criteria Potential surrogatetest correlation Volumetric propertybaselineVerify QC testing Volumetricscomparison to baseline Surrogate (“Quick”)tests Performance tests at“x” frequencySHRP2 Peer to Peer Exchange 2016

BMD TF Work Products

Research Problem Statement RPS prepared by the BMD TF in June 2016 Anticipated Results 1) review of the state-of-the-practice forasphalt mixture design, 2) review the development and state-ofthe-practice for performance testing, 3) development of a RecommendedPractice for Balanced Mixture Design toimplement performance testing in thedesign of asphalt mixtures, and 4) development of a training andimplementation plan and materials tomove BMD ahead in State HighwayAgencies (SHAs). 1 Million tons of HMA placedeach day. Critical to address mix design ina more comprehensive mannerSHRP2 Peer to Peer Exchange 2016

Research Problem Statement – AASHTO Update Favorable response during August SOM Comments from Oak Metcalfe (TS 2d Chair) Technical Section chairs to rank all the proposed researchstatements that were submitted during the SOM meetingat the beginning of August. There are eight total research statements from the SOMwith the BMD statement being the only one in the area ofasphalt mixtures or binder. (There are several in the areaof pavement preservation, including fog seals) Rank each RPS on a scale of 1 to 5, with 5 being thehighest priority. Our rankings are due to Jack by the 16thof September and there will be a group call to decide thefinal rankings on September the 23rd.ETG BMD TF Update - April 2016

Research Problem Statement – Schedule Problem Statements Solicited: July 2016Problem Statements Due: October 2016Evaluations sent to Submitters: Early December 2016Ballot sent to SCOR and RAC Members: Mid-December 2016Ballot Due: February 2017SCOR Meeting: March 2017SHRP2 Peer to Peer Exchange 2016

FHWA Technical Brief - Draft Tech Brief prepared andreviewed by full ETG. Revision work currently beinghandled by the task force. Good document beingmade betterTarget October for final draft.SHRP2 Peer to Peer Exchange 2016

Final Thoughts on Mix Design Key Foundational Points to Keep inMind1.“Use What Works”2.“Eliminate What Doesn’t”3.“Be as Simple as Possible, BePractical, and Be Correct”SHRP2 Peer to Peer Exchange 2016

Thoughts and Questions?http://www.pennyauctionwatch.com/SHRP2 Peer to Peer Exchange 2016

Sep 20, 2016 · Asphaltic concrete for lower layers, VMA terminology used, 2.2% more VMA than current day mixes or 0.9% higher binder conten t . Bryan Engstrom Massachusetts DOT Agency Brian.Pfeifer@illinois.gov Charlie Pan Nevada DOT Agency cpan@dot.state.nv.us Curt Turgeon Minnesota DOT Agency curt.turgeon@