California Asphalt Pavement Association October 26, 2017

SUPERPAVE Specification for Local SUPERPAVE Specification for Local AgenciesAgencies

Frank Farshidi, Ph.D.

Local Agencies can do:

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• Critically review and develop a SUPERPAVE specs for your agency–When was the last time you updated

your pavement specs?

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Caltrans 2015 specs is available to review

Gradation Levels

Aggregate Quality

VMA Requirements

Performance Testing

Asphalt Mix Types – Section 39

Caltrans Standard Specifications 2010

• HMA: Hot mix asphalt Types A and B

• RHMA–G: Rubberized hot mix asphalt, gap-graded

• OGFC: Open-graded friction course, including HMA–O, RHMA–O, RHMA–O-HB

Caltrans Standard Specifications 2015

• HMA: Hot mix asphalt Type A

• RHMA-G: Rubberized hot mix asphalt, gap-graded

• OGFC: Open-graded friction course

• BWC: Bituminous wearing course

• Minor HMA

Aggregate GradingsDense-graded aggregate for Hot Mix Asphalt

(HMA)200 100 50 30 16 8 4 3/8”1/2” 3/4”1” 1½” 2”2½”

200 100 50 16 8 4 3/8”1/2” 3/4”1” 1½”2” 2½”0

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Conventional 19 mm (3/4 inch) MaximumSize Aggregate Mix

Large Stone Mix

Aggregate Gradings RHMA-G, SMA200 100 50 30 16 8 4 3/8”1/2” 3/4” 1” 1½” 2”2½”

200 100 50 30 16 8 4 3/8” 1/2” 3/4”1” 1½”2” 2½”0

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Gap-Graded, Intermediate Stone Content

SMA, GERMANY

SMA, SWEDEN

RHMA-G

AGGREGATE GRADING CHART

200 100 50 30 16 8 4 3/8”1/2” 3/4” 1” 1½” 2”2½”

200 100 50 30 16 8 4 3/8” 1/2” 3/4” 1” 1½” 2” 2½”0

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gap-gradedgap-graded

one-sizeone-size

open-gradedopen-graded

dense-gradeddense-graded

2010 Standard Specs

2015 SUPERPAVE Specs

Superpave Mix Size Designations

Superpave Nom Max Size Max SizeDesignation (mm) (mm)

37.5 mm 37.5 50 25 mm 25 37.5 19 mm 19 25 12.5 mm 12.5 19 9.5 mm 9.5 12.5

Ndesign Table

ESAL (millions)

Ninitial Ndesign Nmax TI

< 0.3 6 50 75 ≤ 7

0.3 to < 3 7 75 115 8 to 10

3 to < 30 8 100 160 11 to 13

≥ 30 9 125 205 ≥ 14

Current Caltrans Mix Design Requirements}

Performance Performance RequirementsRequirements

Mixture Mixture VolumetricsVolumetrics

HMA Type A

Moisture Sensitivity Tests

Tensile Strength Ratio, AASHTO T283

Hamburg Wheel Tracking Device, AASHTO T324

How Can They Be Used?

• Hamburg Wheel Tracking– Rutting performance

combined with moisture susceptibility

– Load (154 lbs)– No. of passes (20,000)– Temperature (50 to 60oC)– Air voids (7 +/- 0.5%)– Tested under water

Example HWTD Results

• Caltrans:– Min Number of Passes at Max Rut Depth of 0.5

inch

Example HWTD Criteria

Binder Grade Type A RHMA-G

PG 58 10,000 15,000

PG 64 15,000 20,500

PG 70 20,000 25,000

PG 76 25,000 _______

Binder Grade Type A RHMA-G

PG 58 10,000 10,000

PG 64 10,000 10,000

PG 70 12,500 12,500

PG 76 15,000 _______

JMF Requirements-Caltrans• Number of Gyrations

Type A RHMA-G

Ninitial =8 Ndesign=50-150

Ndesign= 85

Nmax=130

• Air voids (±1.5%)Type A RHMA-G

Ninitial ≥ 8.0% Ndesign=4.0%

Ndesign ≥ 4.0%

Nmax ≥ 2.0%

JMF-Volumetrics-Verification-Caltrans

Grading Type A RHMA-G

¼-inch 15.5-18.5 ___________

3/8-inch 14.5-17.5 ___________

½-inch 13.5-16.5 18.0-23.0

¾-inch 12.5-15.5 18.0-23.0

Certifications

• Laboratories testing aggregates and HMA qualities for mix design and JMF must be qualified under:

– AASHTO Materials Reference Laboratory program

And– Caltrans’ Independent Assurance Program

• Hot Mix Asphalt Plants: before production, the HMA plant must have a current qualification under Caltrans’ Material Plant Quality Program

HMA Acceptance

• Based on:– Authorized JMF

– Authorized QC plan– Asphalt binder compliance– Visual inspection– Pavement smoothness

• Materials acceptance: sample every 750 tons or one day’s production, whichever is less, except for AASHTO T 283 and AASHTO T 324 (Modified)

• Theoretical maximum specified density

– Using the rice method, the theoretical max density of field-produced mix is determined as the reference density

– Test at random locations that the Engineer selects

– 4 or 6-ich diameter density cores

– At least once every 5 business days

– Take 1 density core for every 250 tons

• Acceptance based on reduced payment factors

– Less than 89% of Gmm density=remove and replace

– More than 99% of Gmm density=remove and replace

Hot Mix Asphalt Density-In Place

QC Density Requirements

• Gauge Measurements

• 3 per 250 tons or 3 per paving day, whichever is greater

• 2 cores per paving day

Smoothness

• Inertial Profiler in lieu of California Profilograph

• International Roughness Index (IRI) for acceptance

• Areas greater than 160 in/mile within 0.1 mile must be corrected to specified mean roughness indexHMA Thickness Mean IRI requirement

> 0.20 foot 60 in/mi or less

≤ 0.20 foot 75 in/mi or less

Smoothness

• End-result specification

• Contractor might need to grind the existing profile prior to paving to meet the smoothness specs

• Encourages best paving practices

• Minimizes starts and stops of paver and more uniform placement of the mat

Smoothness

• HMA pavement within 3 feet from and parallel to the construction joint formed between curbs, gutters, or existing pavement, test pavement smoothness using a 12-foot straightedge

Major Materials Changes Summary

• SUPERPAVE Gyratory compactor

• Hamburg Wheel Tester

• Inertial Profiler

• AASHTO Test Methods

• AMRL

• Increased materials engineering

• Increased cost and testing

Local Agency Choices to Make• 2006 Section 39• 2010 Section 39• 2015 Section 39 (SUPERPAVE)• Adopt and modify for specific needs and conditions

SUPERPAVE Benefits• Tighter tolerance specs• Air voids content ±1.5%• Binder content: For HMA -0.3%,+0.5% for RHMA: -0.4%,

+0.5%• Better smoothness specs• Performance-related specs for in-place density

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• Develop a timeframe and an action plan–Identify a pavement expert in charge,

budget, and timeframe

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• Finalize the changes with feedback from an unbiased pavement expert – Every agency might require minor

customized modifications

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• Collect data and refine– Acknowledge the uncertainty, invite

others inputs, ask questions

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References• AASHTO M 323 - Standard Specification for Superpave Volumetric Mix Design

• AASHTO T 30 - Standard Method of Test for Mechanical Analysis of Extracted Aggregate

• AASHTO T 84 - Standard Method of Test for Specific Gravity and Absorption of Fine Aggregate (ASTM Designation: C 128-12)

• AASHTO T 85 - Standard Method of Test for Specific Gravity and Absorption of Coarse Aggregate (ASTM Designation: C 127-12)

• AASHTO T 164 - Standard Method of Test for Quantitative Extraction of Asphalt Binder from Hot-Mix Asphalt (HMA) (ASTM Designation: D 2172/D 2172M-11)

• AASHTO T 308 - Standard Method of Test for Determining the Asphalt Binder Content of Hot-Mix Asphalt (HMA) by the Ignition Method

• AASHTO T 320 - Determining the Permanent Shear Strain and Stiffness of Asphalt Mixtures Using the Superpave Shear Tester (SST)

• AASHTO T 321 - Standard Method of Test for Determining the Fatigue Life of Compacted Asphalt Mixtures Subjected to Repeated Flexural Bending

References - Continued• AASHTO T 322 - Standard Method of Test for Determining the Creep Compliance

and Strength of Hot Mix Asphalt (HMA) Using the Indirect Tensile Test Device

• AASHTO T 324 - Standard Method of Test for Hamburg Wheel-Track Testing of Compacted Hot-Mix Asphalt (HMA)

• AASHTO T 340 - Standard Method of Test for Determining the Rutting Susceptibility of Hot Mix Asphalt (APA) Using the Asphalt Pavement Analyzer (APA)

• AASHTO TP 107 - Standard Method of Test for Determining the Damage Characteristic Curve of Asphalt Mixtures from Direct Tension Cyclic Fatigue Tests

• AASHTO R 59 - Standard Specification for Recovery of Asphalt Binder from Solution by Abson Method (ASTM Designation D 1856-09)

• ASTM D 7313 - Standard Test Method for Determining Fracture Energy of Asphalt-Aggregate Mixtures Using the Disk-Shaped Compact Tension Geometry

• TEX-248-F Test Procedure for Overlay Test (Texas DOT)

Thank you

949-690-1411

ffarshidi@gmail.com

Questions ?