Airport Pavements â Huge Investment. â« Important to Preserve this Investment. â« Effective Pavement Preservation Program. ⢠Right Pavement. ⢠Right Treatment.
What You Need to Know about Airport Pavement Preservation David K. Hein, P.Eng. Applied Research Associates, Inc.
What it Looks Like New!
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What Do I Do Now?
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Why the Interest in Pavement Preservation?
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FAA Research to Extend Airport Pavement Service Life Airport Pavements – Huge Investment Important to Preserve this Investment Effective Pavement Preservation Program • • •
Right Pavement Right Treatment Right Time
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Construction of Airport Asphalt Pavement Mix Properties Critical Poor Compaction of Longitudinal Joints Results in Raveling & Cracking
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Construction of Airport Rigid Pavement
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Construction of Airport Rigid Pavement
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Proof Rolling
Required on military airfield construction, TM 5‐825.2 Used to locate isolated soft spots in compacted soil Increases compaction of base course to required density Proof Roller • Four large rubber tires • 30,000 lbs (13,600 kg) on each tire • 150 psi (1 MPa) tire pressure Rolling Pattern • 30 coverages • Centre 75 ft (23 m) of Type A runways
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FAA Research to Extend Airport Pavement Service Life Federal Aviation Administration developing new models for pavement performance at the National Airport Pavement Test Facility in Atlantic City
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Concept of Longer Service Life Pavement Condition Index
Preventive Maintenance Reconstruction
Acceptable Serviceability
Unacceptable Serviceability Time
Pavements deteriorate with time through development of a range of distresses Pavement life can be extended with proper maintenance Deterioration ultimately reaches a level of unacceptable serviceability
Current FAA design is typically for a 20‐year pavement life Some pavements last longer than 20 years while others fail prematurely What factors impact extended pavement service life?
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Effective Maintenance Timely Maintenance Retards Rate of Deterioration Rigid Pavements • • • • •
Timely Spall Repairs Effective Patching Materials Crack Sealing Joint Resealing Slab Replacements
Flexible Pavements • • • •
Crack Seals Patches Thin Surfacings (Micro‐Surfacing, Slurry Seal, Fog Seal) Mill and Overlay
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Life‐Cycle Costing
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General Flowchart for Pavement Preservation Pavement Surface/Type Asphalt Concrete
Exposed PCC
SurfacedTreated
Other Features GravelSurfaced
•Drainage improvements •Vegetation control •Etc.
Repeat for other pavement types and features Trigger Values and Timing of Maintenance Distress type, severity and density • Roughness • Rutting • Alligator cracking • Flushing, etc.
Management Aspects
Available Treatments • Hot and cold mix patching • Spray patching (manual chip seal) • Routing and sealing of cracks • Micro-surfacing • Etc.
Treatment Selection
Technical Aspects
• Pavement/maintenance management system
• Roadway functional type • Geographical area/environment
Treatment Implementation
• Other planning tools
• Size of municipality
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Specific Flowchart for Pavement Preservation Asphalt
Exposed
Concrete
PCC
Preservation Type
Pavement Type
Composite
Treated
GravelSurfaced
Treatments Emergency maintenance treatments • Patching using hot or cold mix • Infrared patching • Spray patching (manual chip seal)
Emergency Maintenance
Localized
Surface -
Pavement Defects Loss of friction Loss of surface material and segregation Potholing Surface deformation and rutting, etc
Maintenance
Area Maintenance
Rehabilitation/ Reconstruction
Technology Items • • • • •
Synopsis Specifications and manuals Field performance reports Laboratory and technical reports Investigative and forensic reports
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ACRP Synthesis Project 11‐03 Scope and Objectives Objective • Document how airports implement a pavement maintenance management program, including inspection and tracking pavement condition, scheduling maintenance, identifying necessary funds, and treating distresses in asphalt and concrete pavements
Goal • Document effective practices and differences in maintenance practices by pavement type, airport category and geographical location (e.g., weather and availability of materials) • Information obtained from literature review and survey of airport practices
Target Audience • Airport pavement engineers and pavement maintenance managers and personnel 17
Survey of Maintenance Practices Surveys from 50 airports ranging in size, geographical location,
aircraft operations Over 80% have functional Pavement Management System (PMS) 30% rated PMS as excellent and essential 38 separate M&R treatments identified from survey results Reduced to 24 common M&R treatments • 12 for asphalt pavement surfaces • 9 for concrete surfaces • 3 applicable to both surface types
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Development of PMS 1. Design of APMS Needs of the users Expected results
2. Pavement inventory & evaluation Inventory and database Pavement evaluation Performance prediction
Network Level:
Selecting the right
3. Technology of pavement preservation treatments
section at the right time
4. Identification of needs Levels of service Preventive maintenance
Other pavement preservation needs
5. Prioritization, planning and budgeting
6. Project design and implementation Project Level:
7. Operation, sustainability and enhancement
Designing and implementing the right treatment
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M&R Based on Pavement Condition Index Description
Applicable pavement preservation treatments
86-100
Good – only minor distresses
Routine maintenance only
71-85
Satisfactory – low and medium distresses
Preventive maintenance
56-70
Fair, some distresses are severe
Corrective maintenance and rehabilitation
PCI Rating
41-55 26-40 11-25 0-10
Poor – severity of some of the distresses can cause operational problems Very poor – severe distresses cause operational problems. Serious – many severe distresses cause operational restrictions Failed – pavement deterioration prevents safe aircraft operations
Rehabilitation or reconstruction Rehabilitation and reconstruction Immediate repairs and reconstruction Reconstruction
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Residual Life Time left until asset failure Straight line or decay curve approaches Predicted performance A
B
Asset Condition
Remaining service life
Minimum acceptable service level Past performance
Now Asset Age, years
Now +2
Now +5
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Level of Service Level of Service (LOS) defines desired surface condition Performance curve Pavement Condition Index, PCI
100
Trigger level for crack sealing Target level of service for average network condition Trigger level for overlay (mill and fill) Minimum acceptable level of service for individual sections
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Pavement age, years
Higher LOS can result in higher M&R costs 22
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Preservation Techniques Fog Seal
Crack Seal
Micro-Surfacing
Ultrathin Bonded Wearing Course
Slurry Seal
Thin HMA Overlay
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Catalog of M&R Treatments Both Pavement Types
Texturization using shot blasting Diamond grinding Micro-surfacing
Asphalt Concrete
Sealing and filling of cracks (hot or cold applied sealants) Small area patching (hot mix, cold mix or proprietary material) Spray patching (manual chip seal and mechanized spray patching) Machine patching with AC material Rejuvenators and seals Texturization using fine milling Surface treatment (chip seal) Slurry seal HMA overlay (includes milling) Hot in-place recycling Cold in-place recycling Ultra-thin Whitetopping
Portland Cement Concrete
Joint and crack sealing (with bituminous, silicone, or compression sealants) Partial depth repairs (AC, PCC, and proprietary materials) Full depth repairs (AC, PCC, and proprietary materials) Machine patching using hot mix Slab stabilization and slabjacking Load transfer Crack and joint stitching Hot mix overlays Bonded PCC overlay
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Example of Fact Sheet (Hot Mix Overlay) 1. Optional vibratory dual steel drum rollers 2. Rubber tired rollers Optional material 3. Static dual steel drum rollers transfer vehicle Paver
Hot mix truck Asphalt distributor
Milling machine
Tack coat application
Optional built -in tack coat application
Power broom
Description of Process Resources Purpose and Selection Criteria Typical Service Life and Costs Materials and Construction Airport Experience 25
Survey‐ Use of AC Treatments Survey Result, %
Very Good
Good
84 9 52 43 9
11 7 16 18 11
95 16 68 61 20
19 17 42 13 25
71 66 58 50 50
10 17 0 37 25
5
7
11
0
100
0
27 34 7
14 18 5
41 52 11
39 39 20
55 61 80
6 0 0
0
16
16
0
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Poor
Total
hot-poured sealant cold-applied sealant hot mix Small area (pothole) patching cold mix using proprietary mix Spray patching (includes manual chip seal) Machine patching with AC Milling and machine patching with AC fine milling Texturization using controlled shot blasting Crack sealing with
Performance
Have Tried
Treatment Type
Routine
Usage
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Survey‐ Use of AC Treatments (cont’d) Rejuvenators, fog seals, etc. Surface treatment Slurry seal Micro-surfacing Hot mix overlay Milling and hot mix overlay Hot in-place recycling Cold in-place recycling Whitetopping (PCC overlay)
30 15 23 2 45 45 5 2 7
23 18 25 9 23 18 2 0 7
52 43 48 11 68 64 7 2 14
23 6 10 25 48 58 N/A N/A 60
59 81 75 75 48 42 N/A N/A 20
18 13 15 0 4 0 N/A N/A 20
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End Result Pavement performance curve
Pavement Condition Rating
100
Preventive Maintenance
Change due to a preventive maintenance treatment
70 Maintenance and Rehabilitation Minimum recommended condition Benefit Reconstruction
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Extended pavement life due to preventive maintenance
5
10 Pavement Age, years
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