Superpave The New Frontier

Toni CarrollVulcan Materials

Why Superpave?Improve Performance

◦Low Temp Cracking◦Fatigue Cracking◦Rutting

Materials◦Binder◦Aggregate ◦Mix Design & Testing

Testing & Performance Prediction

Job Format?

No more QCQA!

Most jobs are StandardSome jobs are Method

Changes to Mix SpecificationsTighter Specs

◦Air Voids ±1.5%◦Binder for HMA: -0.3%, +0.5%◦Binder for Rubber: -0.4%, +0.5%

No more VFAVMA Design Vs. Production

Changes to the Mix

Higher Binder Contents◦Compactor changes volumetrics◦Rubber binder content is now a minimum of 7.5 TWM (8.1 DWA)

Changes to the Mix

Coarser gradationsFAA required for ALL mixes, More fractured faces

Change to Fractured Face MethodCurrently a particle is considered

crushed if 25% of the face is fractured.

New procedure requires 50% of the face to be fractured. 2x more fracture!

Compaction: Kneading vs. GyratoryHVEEM Compactor uses

“kneading” motion to compact pucks◦Tamping rod presses down in

various places around the puckGyratory Compactor uses

“gyrating” motion to compact pucks◦Surface the same size as the puck

is rolled in a circular fashion around the puck

Time Saved with Gyratory

Task HVEEM GyratoryGrading Aggs 60 60

Mixing 45 45Compacting 15 20*

Cool Down for Stability

90* -

Stability Test 25 -Cleanup 20 20

TOTAL (Minutes): 255 145

TOTAL (Hours): 4.25 2.4

Technician’s Time: 2 hrs 45 min 2 hrs 5 min

*Does not require technician to be present

Cost to PurchaseCompactor: $40kAccessories: $8kConstruction Costs: $0k-$10k

TOTAL CAPITAL COST: $48,000-

$58,000

Cost to Outsource

Field Samples: $900-$1200Lab Mixed Designs: $5400-

$7500

What to Do on Your JobAvg. Caltrans job may have 20,000-30,000 tons of mix

Need Mix DesignNeed to test for VerificationNeed to test for Production Startup

Need one test for every 4,000 tons

Avg Testing for Job: 5-10 samples

Hamburg Wheel Track General Overview

Weighted steel wheel runs back and forth over HMA samples in a heated water bath

Test PurposePredicts:

◦Rutting Fatigue◦Moisture Susceptibility◦Stripping

Mix Fails Due To:◦Weak aggregate structure◦Inadequate binder stiffness◦Moisture damage

Caltrans’ Reason for HWT

No stability testRutting potentialTests for

moisture sensitivity & stripping

To be used with TSR

How will your mix fare? Stiffer asphalt binders

(higher high temperature grades) do better

Adding liquid antistrip or lime usually improves the HWT results. Improvement with lime is usually more dramatic than with liquid

Harder aggregates do better (Igneous vs. limestone)

Stone on stone mixes do better than dense mixes

Time Required for One Lab Mixed Test

Task Minutes HoursGrading Aggs 60 1.00

Mixing 45 0.75Compacting 20-210 0.33-3.5

Cutting, Prep, & RICE 45 0.75Achieving Temperature 60 1.00Testing 20,000 Passes 390 6.50

Cleanup 20 0.33

TOTAL: 640-830 10.5-14

Cost to PurchaseHWT Machine: $60kAccessories: $2kProfessional Installation:

$1.2k(Optional) Crane: $3kConstruction Costs: $5k-$30k

TOTAL CAPITAL COST: $71,000-$96,000

Cost to OutsourceOnly a few 3rd party machines

in the state

Field Samples: $900-$1700Lab Mixed Samples: $1200-

$2000

What to do on Your JobAvg. job may have 20,000-30,000

tons of mixNeed one test for Mix

Design/VerificationNeed one test for Production

StartupNeed one test for every 10,000

tons

Avg Testing for Caltrans Job: 3-5 samples

Hamburg & TSR TestingCan not hand mix samples for

mix design test resultsMust be run through the hot

plant for mix design testing (also counts as verification sample)

TSR no longer a ratio, must pass dry & wet strength minimum specifications

Freeze thaw required

Hamburg & TSR Testing Cont.

If you cannot meet the minimum HWT or TSR requirements you must test PI and treat your mix using a specified antistrip treatment

HWT Sample AmtsMix Design/VerificationProduction Startup1 per 10,000 tons or 1 per

project, whichever is greater

4 Pucks ≈ 9200 grams (Per Split)

TSR Sample AmtsMix Design/VerificationProduction Startup1 per 10,000 tons or 1 per

project, whichever is greater

6 Pucks ≈ 21,600 grams (Per Split)

Gyratory Sample AmtsMix DesignVerificationProduction Startup1 per 4,000 tons or 2 every 5

paving days, whichever is greater

3 Pucks ≈ 14,100 grams (Per Split)

Verification Sample Tonnages120 lb for each Coarse Agg80 lb for each Fine Agg10 lb for each Supplemental FineMinimum of 50 lb from each RAP

stockpile or 100 lb from the belt

Total Agg: >460lbs-630lbs (1/4 Ton!)

HMA: ≥250lbs◦Likely will need ≈650-1000lbs (1/4-1/2

Ton!)

Sample LocationsQC samples from anywhere per CT125QA TSR & Hamburg sampled from:

◦Automatic sampling device at the plant◦Automatic sampling device at the truck◦Windrow

All other QA HMA samples from:◦Automatic sampling device at the plant◦Automatic sampling device at the truck◦Windrow◦Mat behind the paver

Automatic Plant Samplers

Sample box attaches here

Automatic Plant Samplers

Automatic Truck Samplers

Automatic Truck Samplers

On Site Storage?Too much volume of samples

for retentionWork with Caltrans to

develop onsite storage with their lock for QA sample retention

No More Lost Samples!

QC Nuclear Density TestingRequired to perform QC

Nuclear Gauge Density (CT375) for all non-minor jobs

3 per 250 tons or 3 per paving day (whichever is greater)

Not used for acceptance, still using cores for acceptance

JMF ModificationsNow need new JMF if changing

binder source, LAS producer, or LAS dosage

Can do a modification instead of full mix design instead

Only test at OBCCaltrans verifies Hamburg, Air

Voids, VMA, DP, & TSR (if desired)Each modification costs $2000

Verification ChangesMust verify with plant set

within 0.2% of OBC binder content

Only two tries for free, additional tries are $3000

April 11, 2023

AMRL AccreditationCaltrans will require AMRL

accreditation to move towards national standards and hopefully reduce workload on the Caltrans IA staff.

Implementation will be with Superpave specs in July 2014

36

April 11, 2023

AMRL’s RoleAccredits any of your labs

that do testing for Caltrans Superpave mix designs

Does not need to accredit basic labs (aka. only gradations, oil content, SE, etc.)

Accredits lab & equipment, does not certify each individual technician

Proficiency Sample Program37

April 11, 2023

Caltrans’ IA RoleTechnician Proficiency TestingTechnician Certification

◦Still certify for HVEEM jobs◦Some test methods do not have equivalent AASHTO methods.

Caltrans Laboratory Accreditation Manual

Reference Sample Program

38

AMRL FeesApplication ($250 one time)Admin Fees ($725 annually)

◦$350 Base Fee ◦15 methods*$25/method ◦ Applied after 1st year

Basic Fees for 2 Scopes ($900 in assessment year)

Individual Test Fees ($2960 in assessment year)Proficiency Samples ($1480 annually)

TOTAL: ≈$4135 on a year

April 11, 2023

Out-of-SequenceNext tour: Oct 2014-June

2015Can be 1.5x normal feeGroup w/ other labs

Fee may not apply to new laboratories, contact AMRL for estimate.

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Questions?Comments?