Montana’s VolumetricMontana’s VolumetricffSpecificationSpecification

Scott BarnesScott BarnesTesting EngineerTesting Engineer

Montana DOTMontana DOTsbarnes@mt.govsbarnes@mt.gov

OverviewOverviewOverviewOverview

•• Why am I here?Why am I here?•• Why am I here?Why am I here?–– ‘New’ system in Montana, low bid, but ‘New’ system in Montana, low bid, but

quality is most important underquality is most important underquality is most important under quality is most important under construction. construction.

–– Volumetrics only mix quality requirementVolumetrics only mix quality requirementVolumetrics only mix quality requirement Volumetrics only mix quality requirement under construction.under construction.

–– Hamburg Density and RideHamburg Density and RideHamburg, Density and Ride.Hamburg, Density and Ride.–– First projects let in 2003, never looked First projects let in 2003, never looked

backbackbackback

A little History, how we got A little History, how we got y gy gherehere--•• Volumetric properties weren’t really new.Volumetric properties weren’t really new.•• Marshall trailers, all jobs beginning 1984.Marshall trailers, all jobs beginning 1984.Marshall trailers, all jobs beginning 1984.Marshall trailers, all jobs beginning 1984.

–– Volumetrics and gradationsVolumetrics and gradations–– Idea was developed into a NHI course laterIdea was developed into a NHI course laterIdea was developed into a NHI course laterIdea was developed into a NHI course later–– Mix adjustments, continuous, begun.Mix adjustments, continuous, begun.–– Density in place voidsDensity in place voids –– Cores NuclearCores Nuclear–– Density, in place voids Density, in place voids –– Cores, NuclearCores, Nuclear–– AC contentAC content--Extractions, Nuc AC, Ign. OvensExtractions, Nuc AC, Ign. Ovens

History How we got hereHistory How we got here....History, How we got here........History, How we got here....

•• Statistical payment Statistical payment –– GradationsGradations–– Lot systemsLot systemsyy–– Random SamplingRandom Sampling–– Incentives & DisincentivesIncentives & Disincentives

Asphalt Binder ResearchAsphalt Binder Researchpp

•• 1990s Dr Wynn Jennings, MSU, Molecular 1990s Dr Wynn Jennings, MSU, Molecular Size, blending of Montana AsphaltsSize, blending of Montana Asphalts

•• Dr Joe Armijo & Murari Pradham, Montana Dr Joe Armijo & Murari Pradham, Montana Asphalt Binders and New Polymer ModifiersAsphalt Binders and New Polymer Modifiers–– Test projectsTest projects–– Led to widespread Polymer Modified asphalt Led to widespread Polymer Modified asphalt

useuseuseuse–– All polymers OKAll polymers OK

•• PG binders early adoptionPG binders early adoption•• PG binders, early adoptionPG binders, early adoption

Mix Research and HistoryMix Research and HistoryMix Research and HistoryMix Research and History•• Marshall mixes rutting issues EasternMarshall mixes rutting issues Eastern•• Marshall mixes, rutting issues Eastern Marshall mixes, rutting issues Eastern

MontanaMontana–– Largely sand mix ‘B’Largely sand mix ‘B’–– Largely sand mix BLargely sand mix B–– “Anti“Anti--rutting”rutting”

‘D’ mix high VMA high asphalt content high‘D’ mix high VMA high asphalt content high–– D mix, high VMA, high asphalt content, high D mix, high VMA, high asphalt content, high aggregate quality, no naturals, Meets aggregate quality, no naturals, Meets SuperpaveSuperpaveSuperpaveSuperpave

–– Good mix but we can do betterGood mix but we can do better–– Hamburg researchHamburg research –– wanting performancewanting performanceHamburg research Hamburg research wanting performance wanting performance

predictionprediction

So what did we do?So what did we do?So what did we do?So what did we do?

•• Along came SuperpaveAlong came Superpave•• Along came SuperpaveAlong came Superpave•• Liked what we saw but some issuesLiked what we saw but some issues

L h lt t t b b t 1%L h lt t t b b t 1%–– Lower asphalt content by about 1%Lower asphalt content by about 1%–– Lower aggregate quality requirementsLower aggregate quality requirements

No strength measureNo strength measure–– No strength measureNo strength measure•• Adopted Adopted CarefullyCarefully

Th ti ll idTh ti ll id–– There was essentially no guidance on There was essentially no guidance on specificationsspecifications

–– Involved converting to aInvolved converting to a GRADATIONGRADATIONInvolved converting to aInvolved converting to a GRADATIONGRADATIONspecificationspecification..

SuperpaveSuperpaveSuperpave Superpave

•• Liked it, after a bit of tweaking, really Liked it, after a bit of tweaking, really not not thatthat much different.much different.

•• Contractors were meeting the Gradation Contractors were meeting the Gradation specs (pay factors!)specs (pay factors!)specs, (pay factors!), specs, (pay factors!), –– Volumetric Req’s?Volumetric Req’s?

•• More good training!More good training!•• More good training!More good training!•• Good equipment!Good equipment!•• Superpave without the TwistSuperpave without the Twist

Volumetric Results Not a Volumetric Results Not a ‘Gamble’ With the Gyratory‘Gamble’ With the Gyratory‘Gamble’ With the Gyratory.‘Gamble’ With the Gyratory.

99

How to achieve Volumetrics ??How to achieve Volumetrics ??How to achieve Volumetrics ??How to achieve Volumetrics ??

•• All we really want is:All we really want is:–– Gradation, Asphalt Content, Voids, VMA, VFA, Gradation, Asphalt Content, Voids, VMA, VFA, , p , , , ,, p , , , ,

Dust Asphalt ratioDust Asphalt ratio–– All in spec, then we have PERFORMANCE?All in spec, then we have PERFORMANCE?–– No “Wiggle Room” No “Wiggle Room”

•• Hadn’t controlled for volumetrics,Hadn’t controlled for volumetrics,Hadn t controlled for volumetrics,Hadn t controlled for volumetrics,–– Had no idea of capabilitiesHad no idea of capabilities

MDT’s Performance SpecificationMDT’s Performance Specification

•• All Superpave Volumetric properties, at 2% All Superpave Volumetric properties, at 2% incentive eachincentive eachincentive eachincentive each–– Use all four volumetric propertiesUse all four volumetric properties

•• If 3 properties in incentive, 4% bonusIf 3 properties in incentive, 4% bonus–– 12% max12% max

•• Hamburg, Design and Production requirementsHamburg, Design and Production requirements

•• That’s IT! Simple .. .. .. !!That’s IT! Simple .. .. .. !!

•• Focus on helping Contractor to make the best Focus on helping Contractor to make the best possible mix!possible mix!–– Owner will get best possible value!Owner will get best possible value!–– Owner will get best possible value!Owner will get best possible value!

Volumetric Requirements.Volumetric Requirements.qqTargets and RangesTargets and Ranges•• Voids in Mineral AggregateVoids in Mineral Aggregate (VMA)(VMA) 13 to 1713 to 17•• Voids in Mineral AggregateVoids in Mineral Aggregate (VMA)(VMA) 13 to 17 13 to 17

+/+/-- 0.60.6

•• Voids Filled with Asphalt (VFA)Voids Filled with Asphalt (VFA) 65 to 80 65 to 80 +/+/-- 5.05.0

•• Voids in Total Mix (VTM)Voids in Total Mix (VTM) 3.4 to 4.0 3.4 to 4.0 +/+/-- 1.01.0

•• Dust Asphalt Ratio (D/A)Dust Asphalt Ratio (D/A), Meet Dust Effective , Meet Dust Effective Asphalt Ratio at mix design. Asphalt Ratio at mix design.

1212

–– No target limits in production,No target limits in production, +/+/-- 0.20.2

Other Necessities: Other Necessities: •• Field test trailers, Field test trailers,

Gyros and Ignition ovensGyros and Ignition ovens–– Gyros and Ignition ovensGyros and Ignition ovens–– Testing, full time, on the job, until completionTesting, full time, on the job, until completion–– StartupStartup veryvery importantimportant lotslots of testing andof testing and–– Startup Startup veryvery important, important, lotslots of testing and of testing and

adjustment as needed, by Contractor adjustment as needed, by Contractor •• Some ‘Free mix’ no QA until second lot,Some ‘Free mix’ no QA until second lot,Some Free mix no QA until second lot, Some Free mix no QA until second lot,

target settarget set•• Contractor may change targets at the end !Contractor may change targets at the end !Contractor may change targets at the end !Contractor may change targets at the end !

–– Similar to PWL system, no chasing bad targetSimilar to PWL system, no chasing bad target–– Encouraged to set targets early to maximize Encouraged to set targets early to maximize

1313

cou aged to set ta gets ea y to a ecou aged to set ta gets ea y to a emix in QAmix in QA

Other Necessities:Other Necessities:Other Necessities:Other Necessities:

•• Density, good field controlDensity, good field control–– We use 93% minimumWe use 93% minimum–– 94 to 95% incentive range94 to 95% incentive range–– 5% incentive available.5% incentive available.

•• Ride, brings it all together.Ride, brings it all together.–– Up to 25% incentive possible depending onUp to 25% incentive possible depending on–– Up to 25% incentive possible depending on Up to 25% incentive possible depending on

class of road and work.class of road and work.

•• Good CommunicationGood Communication -- SalesSales

1414

•• Good Communication Good Communication -- SalesSales

More NecessitiesMore NecessitiesMore NecessitiesMore Necessities

•• Good computer program to track it allGood computer program to track it all• Contractor controls Asphalt Content,controls Asphalt Content, andand--Contractor controls Asphalt Content, controls Asphalt Content, andand

–– Asphalt separate pay itemAsphalt separate pay item–– Asphalt content big factor in volumetricAsphalt content big factor in volumetricAsphalt content big factor in volumetric Asphalt content big factor in volumetric

properties, density, ride, durability, properties, density, ride, durability, permeability, (and permanent deformation).permeability, (and permanent deformation).p y ( p )p y ( p )

•• Money for the more expensive testing Money for the more expensive testing equipment . . . !equipment . . . !

1515

equipment . . . !equipment . . . !

Montana Modified Ignition OvenMontana Modified Ignition OvenMontana Modified Ignition OvenMontana Modified Ignition Oven

1616

Hamburg RequirementsHamburg Requirements

•• Low requirements, separator of ‘good’ from Low requirements, separator of ‘good’ from ‘b d’ i‘b d’ i‘bad’ mix.‘bad’ mix.

•• Applies to the Mix Design Applies to the Mix Design -- HurdleHurdle

•• Applies during Plant Mix Production and must Applies during Plant Mix Production and must be met to qualify for QA incentive andbe met to qualify for QA incentive andbe met to qualify for QA incentive and be met to qualify for QA incentive and prevent shutprevent shut--down order.down order.

•• Must be Sampled before second Lot of Must be Sampled before second Lot of Production for confirmation test.Production for confirmation test.

1717•• Additional testing at any time as needed.Additional testing at any time as needed.

Quality IncentiveQuality IncentivePotentialPotential

•• 12 Percent for Volumetrics12 Percent for Volumetrics

•• 5 Percent for Density5 Percent for Density

•• 10 to 25 Percent for Ride10 to 25 Percent for Ride

42 Percent incentive is achievable42 Percent incentive is achievable

1818

How is it Working?How is it Working?How is it Working?How is it Working?•• MDT perspectiveMDT perspective ––•• MDT perspective MDT perspective

–– Quality has improved quite remarkablyQuality has improved quite remarkablyBetter relations on the projectsBetter relations on the projects–– Better relations on the projectsBetter relations on the projects

–– Incentives being bid back inIncentives being bid back inWe cannot messWe cannot mess anythinganything up and meetup and meet–– We cannot mess We cannot mess anythinganything up and meet up and meet volumetrics!volumetrics!Paying attention to the details slower steadierPaying attention to the details slower steadier–– Paying attention to the details, slower steadier Paying attention to the details, slower steadier productionproduction

–– Very pleased from project crews on up to theVery pleased from project crews on up to the

1919

–– Very pleased from project crews on up to the Very pleased from project crews on up to the Construction EngineerConstruction Engineer

How is it Working?How is it Working?How is it Working?How is it Working?•• Contractor perspectiveContractor perspective•• Contractor perspectiveContractor perspective

–– Found the “volumetric dial”Found the “volumetric dial”Got the State out of our control shacksGot the State out of our control shacks–– Got the State out of our control shacksGot the State out of our control shacks

–– Most had some difficulties with their first Most had some difficulties with their first projectsprojectsprojectsprojects

–– Crushing, including QC has become major Crushing, including QC has become major concentrationconcentrationconcentrationconcentration

–– Learned what it takes to be consistentLearned what it takes to be consistent

2020

Montana’s VolumetricMontana’s VolumetricMontana s VolumetricMontana s VolumetricSpecificationSpecificationpp

It i th j t V l t iIt i th j t V l t iIt is more than just VolumetricsIt is more than just VolumetricsIt is:It is:

•• Following Superpave MethodologiesFollowing Superpave Methodologies•• An end result specificationAn end result specificationAn end result specificationAn end result specification•• Follows statistical acceptance Follows statistical acceptance

methodsmethodsmethodsmethods

Hamburg Wheel Tracker Progress Hamburg Wheel Tracker Progress g gg g1992 Results1992 Results

•• 1992 Results 1992 Results –– Tadd Butt Tadd Butt –– Koch Asphalt Koch Asphalt Data Data

2003 Typical Results2003 Typical Results2003 Typical Results2003 Typical Results0

2000 4000 6000 8000 10000 12000 14000 16000 18000 20000

-4

-2

ng

-6

mm

of r

uttin

-10

-8

-14

-12

-16

Typical Hamburg Results TodayTypical Hamburg Results TodayWITH VOLUMETRIC ACCEPTANCEWITH VOLUMETRIC ACCEPTANCE

Hamburg Wheel Tracking Device 2007

-2

0

5

1000

2000

3000

4000

5000

6000

7000

8000

9000

1000

0

1100

0

1200

0

1300

0

1400

0

1500

0

1600

0

1700

0

1800

0

1900

0

2000

0

-6

-4

-8

Rut

Dep

th (m

m)

-12

-10

-16

-14

Number of passes

Q i ?Q i ?Questions?Questions?QQ

If ContractorsIf Contractors andand MDT Project ManagersMDT Project ManagersIf Contractors If Contractors andand MDT Project Managers MDT Project Managers are happy, Everybody is Happy!are happy, Everybody is Happy!

Montana’s VolumetricMontana’s VolumetricMontana s VolumetricMontana s VolumetricSpecificationSpecificationSpecificationSpecificationPresentation OverviewPresentation Overview

•• How we got where we are today.How we got where we are today.(Specification Development)(Specification Development)(Specification Development)(Specification Development)

•• Unusual portions of the specificationUnusual portions of the specification•• Review of the specificationReview of the specification•• Contractors perspectiveContractors perspectivep pp p•• Owner/agency perspectiveOwner/agency perspective

Volumetric Specification Volumetric Specification ppDevelopmentDevelopment

•• Benefits of modifying the existing Benefits of modifying the existing specificationspecification–– Transition from “method” to “end result” Transition from “method” to “end result”

specification specification –– Easier to evaluate with newer equipmentEasier to evaluate with newer equipment–– Better represents the actual mixBetter represents the actual mix–– Simplified contract administrationSimplified contract administration