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307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE

Pavement Materials, Maintenance, and

SpecificationsAssociation of California Airports – South Lake Tahoe – September 16, 2015

Presenter

Presentation Notes


Disclaimer

This is a technical / materials presentation only. Potential impacts on funding, grants, FAA

acceptance, FAA Orders, Public Law, etc. are not considered in detail.


Plantmix / Hot Mix Asphalt

• “Stiff” enough to support the anticipated loads• “Soft” enough to be durable

– Resist fatigue– Resist environmental stresses and aging

• Adequate friction• Smooth, uniform texture• No FOD• Minimum Life Cycle Cost / minimal disruption


Demands Differ

• Major commercial vs. small general aviation• Runways vs. taxiways vs. aprons• Landside vs. airside• Mixed use• Different climates• Changes over time

Thus, materials & criteria should also differ

Presenter

Presentation Notes

Mixed use – GA airports that serve slurry tankers or other occasional heavy aircraft


Pavement Maintenance Starts Before Construction


Pavement Management


P-401 / P-403

• Guidance on binder• Guidance based on aircraft weights• Three gradations to choose from• Mixture parameters designed and proven on

airports (empirically)• Material requirements and PWL are

integrated

Presenter

Presentation Notes

Some judgment is still required to make optimal use of this guidance


Why Not P-401 / P-403?

• Marshall mix design method becoming uncommon

• FAA Superpave is unfamiliar to many• $2,500 to $5,000 (or more) for a mix design• Not all producers can meet the specification

– Voids in mineral aggregate (VMA)

• Generally results in higher prices

Presenter

Presentation Notes

Higher prices are ok if higher value is obtained


Why Not Caltrans Mix?

• Readily available, right?• Lots of experience with the spec and

materials, right?• Good enough for Caltrans, right?

Maybe


AC 150/5370-10G 7/21/2014

The use of state highway department specifications for airfield pavements subject to aircraft loading by aircraft greater than 12,500 pounds and less than 60,000 pounds requires a modification to standards in accordance with FAA Order 5100.1.

307-213-0223 [email protected] Mike Robinson, PE

Airports vs. Highways

Airports• Fewer passes• Greater weights• Higher shear• Mixes less rut resistant• Generally higher

compaction requirements• Pay based on statistical

evaluation

Highways• More passes• Lower weights• Lower shear• Focus on high rut resistance• Generally lower

compaction requirements• Acceptance

– Non-statistical– Different criteria


Caltrans Spec is Evolving• 2006 Standard

– More gradation options, but no compaction control

• 2010 Standard– More volumetrics, three placement types

• 2015 Standard – Superpave

Spec itself is complicated and difficult to understand and follow

Presenter

Presentation Notes

2010 – 68 pages, 2015 RSS - 65 pages


FAA Gradation 1 vs Caltrans

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SIEVE SIZE, mm

Comparison of Gradation Specifications - Gradation 1 vs Caltrans

Max Density LineFAA Gradation 1

0.075 0.60 1.18 2.36 4.75 9.5 12.5 19.0 25.0 37.5 50.0



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Max Density LineFAA Gradation 1CT 2006 3/4" max-med

0.075 0.60 1.18 2.36 4.75 9.5 12.5 19.0 25.0 37.5 50.0



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Max Density LineFAA Gradation 1CT 2006 3/4" max-medCT 2010 3/4"

0.075 0.60 1.18 2.36 4.75 9.5 12.5 19.0 25.0 37.5 50.0



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SIEVE SIZE, mm


Max Density LineFAA Gradation 1CT 2006 3/4" max-medCT 2010 3/4"CT 2015 3/4"

0.075 0.60 1.18 2.36 4.75 9.5 12.5 19.0 25.0 37.5 50.0



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SIEVE SIZE, mm


Max Density LineFAA Gradation 1CT 2006 3/4" max-medCT 2010 3/4"CT 2015 3/4"CT 2015 1"

0.075 0.60 1.18 2.36 4.75 9.5 12.5 19.0 25.0 37.5 50.0

13% more passing the 3/8”



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Max Density Line

FAA Gradation 2

0.075 0.60 1.18 2.36 4.75 9.5 12.5 19.0 25.0 37.5 50.0



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Max Density Line

FAA Gradation 2

CT 2006 1/2" max-med

0.075 0.60 1.18 2.36 4.75 9.5 12.5 19.0 25.0 37.5 50.0



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Max Density Line

FAA Gradation 2


CT 2010 1/2"

0.075 0.60 1.18 2.36 4.75 9.5 12.5 19.0 25.0 37.5 50.0



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Max Density Line

FAA Gradation 2


CT 2010 1/2"

CT 2015 1/2"

0.075 0.60 1.18 2.36 4.75 9.5 12.5 19.0 25.0 37.5 50.0

9.5% more passing the 3/8” Can have material retained on the ¾”

Presenter

Presentation Notes

Unlikely to find anything other than ½” and ¾” Caltrans mixes “on the shelf”


So What Do You Do?

• Follow FAA guidance• Adopt the Caltrans specification• Create your own specification


Follow FAA GuidanceAdvantages

• Protects funding• Proven history• Clear guidance • Statistical acceptance (sort

of)• High compaction

requirements• Joint compaction

requirements

Disadvantages• May have to create a new

mix design ($$)• May have to validate an old

mix design ($)• Expect increasing difficulty

finding laboratories with experience and equipment for Marshall

• Mix cost is generally more expensive

Presenter

Presentation Notes

Remember to differentiate between cost and value


Adopt CaltransAdvantages

• Familiar to many contractors and producers (sort of)

• May be familiar to you (but probably not)

• Probably cheaper, but probably less value

Disadvantages• May affect funding• Which version?• May still have to run a new

mix design• May still have to validate

an old mix design• Criteria is for highways, not

airports• Unnecessarily complicated

AAPTP 06-05 Offers Guidance


Create Your OwnAdvantages

• Tailored to your:– Loading– Climate– Experience

• Can take advantage of:– The best of existing specs– Recent research– Local materials, knowledge &

experience• Can maximize pavement

performance, life, and value

Disadvantages• May affect funding• May have to run a new mix

design• May have to validate an old

mix design• Takes some time & effort


Things To Focus On• Binder• Aggregate Quality• Aggregate Gradation (Maximum Aggregate

Size)• Mixture Properties• Placement Requirements• Contractor Quality Control• Acceptance Methods & Criteria


Binder• Follow FAA Guidance• Airport Asphalt Pavement Technology

Program (AAPTP) Report 04-02• Available binders may be limited – market

usually driven by state DOT• Low-temperature grade important for

thermal cracking• High-temp grade / polymers important for

rutting resistance


Aggregate Quality

• State and FAA requirements are good• Higher quality = higher performance

– Increased fracture improves rutting resistance– Moisture sensitivity is important– More expensive

• Don’t buy higher quality than you need if you have the choice


Aggregate Gradation• Gradation affects voids in mineral

aggregate (VMA) which affects durability

• Maximum aggregate size affects:– Permeability– Minimum lift thickness (ROT 3 x maximum)– Segregation potential– Appearance / FOD potential


Mixture Properties• Rutting resistance vs. durability• Things to consider:

– VMA requirements– Laboratory compaction requirements– Target air voids

• Richer, finer mixes tend to be less permeable, easier to compact, less likely to segregate, and be more durable, but also more likely to rut. They also tend to cost more.


Placement Requirements

• Uniformity– Density, thickness, appearance, smoothness

• In-place air voids– Highways – 8% or less– Airports – 5% or less


Contractor Quality Control

• Better to have those who control the process monitor the process

• Many / most already do it, so you are likely paying for it

• Tends to generate more attention and involvement


Acceptance Criteria

• Assess conformance with requirements• If acceptable

– Supports payment– Allows you to monitor performance and

adjust

• If not acceptable– Provides protection– Provides basis for mitigation / penalty


The Desired Outcome

• Increased likelihood of a high quality pavement

• Better performance– Short term– Long term– Delays / reduces need for maintenance (and

associated disruption)

• Some money now saves much money later.

Presenter

Presentation Notes

Regardless of which approach you take Make it as easy as possible for the contractor and producer to give you what you want.


Requires some…

attention to detail


And you should…


But if you deliver a simple, consistent message…


You should have a successful project, and create a long-lasting pavement,

postponing the need for maintenance.

Have you ever noticed that your pavement is deteriorating at a fast rate?

Does a new operator want to bring in heavier aircraft than the current fleet mix?

Are you having an airshow that requires much heavier aircraft to land at the airport?

Do you wonder why there are blank data fields on your FAA Form 5010?

Do you want to ensure you have met your funding obligations as a Sponsor?

Standard Method of Reporting Airport Pavement Strength - PCN

An aircraft’s particular gross weight and tire gear configuration contribute to individual Aircraft Classification Numbers (ACN)

Based on soil strength, layer thicknesses and types, field observations, and calculations: FAA computer software formulate a Pavement Classification Number (PCN) for each pavement area

Ensure PCN > ACN , or early life pavement failure & increased maintenance needs are anticipated

PCN reporting is included in AC 150/5380-7B for Airport Pavement Management Program (PMP)

The PCN data field has been added to the FAA Form 5010

During airport inspections, the FAA will ask the airport owner to provide Runway PCN

With release of AC 150/5320-6E, the “design aircraft” concept has been replaced

PCN data collection and reporting is AIP eligible

The first AC and supporting software (COMFAA) was released in August 2011, with latest update in August 2014.

The FAA requires all public-use paved runways at all Part 14 CFR 139 certified airports to be assigned PCN data.

Eventually, all paved runways at all airports should be assigned PCN data for AIP eligibility

Subgrade characteristics, CBR or K values from Geotechnical Investigation

All pavement section material layers and thickness

Visual observation of the pavement Aircraft fleet mix Ground Traffic Pattern

Data can be obtained with field investigation or record drawings and previous reports.

The PCN system uses a coded format to report information. An example is 62/F/A/W/T

The numerical value indicates load-carrying capacity

The pavement type is either Flexible or Rigid There are four standard subgrade strengths

(coded A, B, C, or D). Allowable tire pressure (coded W, X, Y, or Z) Method used (technical study or using aircraft)

Fleet Mix

Support spreadsheet

COMFAA

PCN Calculation worksheet

Charts

PCNs found to be compatible with current fleet mix: All Runways, Taxiway D, and Terminal Apron West

Three Areas found to have ACNs larger than the allowable PCN Taxiways A, B, and C-2 (Section #5) Taxiway C (Section #6) Terminal Apron East (Section #9)

Pavement overload evaluation ICAO outlines permissible overload operations based on

minor or limited traffic having ACNs that exceed the reported PCN

For flexible pavements, occasional traffic cycles by aircraft with an ACN not exceeding 10% of the reported PCNshould not adversely affect the pavement

The annual number of overload traffic cycles should not exceed 5% of the total operations

Airport owners should review relevant pavement condition on a regular basis and should review criteria for overload operations, since excessive repetition of overloads can cause severe shortening of pavement life or require major rehabilitation of the pavement

Little guidance is given as to the impact of overload operations and how to calculate or define

Results do not recommend Owner allow unlimited operations of large aircraft at the areas indicated where ACN > PCN

Further analysis of the pavement sections and geotechnical investigation of the overload areas is recommended

The Owner may wish to consider a future pavement strengthening project to determine the approach for obtaining the necessary PCNs in these areas

ACN and PCN relationship FAA AC 150/5335-5C COMFAA software and outputs Reporting information

Questions???

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