307-213-0223 [email protected] Mike … and PCNs.pdfAdvantages • Protects funding •...
Transcript of 307-213-0223 [email protected] Mike … and PCNs.pdfAdvantages • Protects funding •...
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
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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.
307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
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
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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
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Pavement Maintenance Starts Before Construction
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Pavement Management
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Pavement Management
307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
Pavement Management
307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
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
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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
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Why Not Caltrans Mix?
• Readily available, right?• Lots of experience with the spec and
materials, right?• Good enough for Caltrans, right?
Maybe
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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.
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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
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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
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FAA Gradation 1 vs Caltrans
0
10
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% P
ASSI
NG
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
307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
FAA Gradation 1 vs Caltrans
0
10
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% P
ASSI
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SIEVE SIZE, mm
Comparison of Gradation Specifications - Gradation 1 vs Caltrans
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
307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
FAA Gradation 1 vs Caltrans
0
10
20
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% P
ASSI
NG
SIEVE SIZE, mm
Comparison of Gradation Specifications - Gradation 1 vs Caltrans
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
307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
FAA Gradation 1 vs Caltrans
0
10
20
30
40
50
60
70
80
90
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% P
ASSI
NG
SIEVE SIZE, mm
Comparison of Gradation Specifications - Gradation 1 vs Caltrans
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
307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
FAA Gradation 1 vs Caltrans
0
10
20
30
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50
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% P
ASSI
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SIEVE SIZE, mm
Comparison of Gradation Specifications - Gradation 1 vs Caltrans
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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FAA Gradation 2 vs Caltrans
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% P
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SIEVE SIZE, mm
Comparison of Gradation Specifications - Gradation 2 vs Caltrans
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
307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
FAA Gradation 2 vs Caltrans
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% P
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SIEVE SIZE, mm
Comparison of Gradation Specifications - Gradation 2 vs Caltrans
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
307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
FAA Gradation 2 vs Caltrans
0
10
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% P
ASSI
NG
SIEVE SIZE, mm
Comparison of Gradation Specifications - Gradation 2 vs Caltrans
Max Density Line
FAA Gradation 2
CT 2006 1/2" max-med
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
307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
FAA Gradation 2 vs Caltrans
0
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% P
ASSI
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SIEVE SIZE, mm
Comparison of Gradation Specifications - Gradation 2 vs Caltrans
Max Density Line
FAA Gradation 2
CT 2006 1/2" max-med
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”
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So What Do You Do?
• Follow FAA guidance• Adopt the Caltrans specification• Create your own specification
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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
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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
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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
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Things To Focus On• Binder• Aggregate Quality• Aggregate Gradation (Maximum Aggregate
Size)• Mixture Properties• Placement Requirements• Contractor Quality Control• Acceptance Methods & Criteria
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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
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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
307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
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
307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
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.
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Placement Requirements
• Uniformity– Density, thickness, appearance, smoothness
• In-place air voids– Highways – 8% or less– Airports – 5% or less
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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
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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
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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.
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Requires some…
attention to detail
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And you should…
307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
But if you deliver a simple, consistent message…
307-213-0223 [email protected] Mike Robinson, PE307-213-0223 [email protected] Mike Robinson, PE
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
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???