View
326
Download
6
Category
Tags:
Preview:
Citation preview
Rehab & Maint. HMA Overlays 1
Flexible Pavement Maintenance and Rehabilitation
HMA Overlays
Introduction and Functional Overlays
Senior/GraduateHMA Course
Rehab & Maint. HMA Overlays 2
Pavement DataCollection
Projectevaluation
Select feasiblealternatives
ReconstructionRestorationRecyclingResurfacing
Life - cycle costs
Non- monetary factors
Select preferredalternatives
Detailed PS & E
Construction
MonitorPerformance
Steps In The Rehabilitation Process
Rehab & Maint. HMA Overlays 3
Rehabilitation Feasibility
Preventive maintenance
Surface Treatment
Thin Overlay
ReconstructionCritical condition
AGE or ESAL
Thick Overlay
PAVEMENT CONDITION
Excellent
Failed
Rehab & Maint. HMA Overlays 4
Pav
emen
t C
ondi
tion
Alt.-A
Alt.-B
Terminal Serviceability Index
Analysis Period
Analysis Period
RSL
Rehab & Maint. HMA Overlays 5
Covered in this module
• HMA Overlays over HMA pavements– Functional – Structural
• HMA Overlays over PCC pavements
Rehab & Maint. HMA Overlays 6
Overlay Types
• Functional overlays – Typically used to address surface
distresses or improve ride quality– Generally not designed and rely on past
experience• Structural overlays
– Correct structural deficiencies and are designed using the methods presented (or other methods)
Rehab & Maint. HMA Overlays 7
Thin Overlay Thick Overlay
Surface Defects Structural Defects
Selection of an Overlay to Correct Deficiencies
Rehab & Maint. HMA Overlays 8
Functional Overlays
• Remedy functional deficiencies• Minimum constructable thickness• May involve surface milling and repair with
overlay
Rehab & Maint. HMA Overlays 9
Functional Deficiencies
• Adversely affect highway user– Poor surface friction– Hydroplaning– Excess surface distortion
• Rutting• Potholes• Faulting• Settlement
Rehab & Maint. HMA Overlays 10
Surface Friction
• Force developed at tire-pavement interface that prevents sliding
• Factor influencing– Microtexture– Macrotexture– Transverse slope
• Poor friction can be caused by polishing or bleeding
Rehab & Maint. HMA Overlays 11
Photo of poor surface friction
Rehab & Maint. HMA Overlays 12
Hydroplaning
• Tires ride on thin film of water and lose contact with the pavement
• Hydroplaning is worsened by water standing on the pavement and is affected by the following – Wheelpath rutting– Lack of surface texture– Lack of cross slope
Rehab & Maint. HMA Overlays 13
Photo of rutting in wheelpaths
Rehab & Maint. HMA Overlays 14
Structural Overlays
Flexible Pavement Maintenance and Rehabilitation
Rehab & Maint. HMA Overlays 15
Surface Roughness
• Irregularities in the pavement surface that adversely affect ride quality, safety, and vehicle maintenance costs
• HMA Pavements– Heaves, settlements– Deteriorated cracks– Potholes– Raveling
• PCC Pavements– Heaves, settlements– Spalling– Faulting– Curling/warping– Texture application
Rehab & Maint. HMA Overlays 16
Photo of raveling
Rehab & Maint. HMA Overlays 17
Options for Correcting Functional Deficiencies
• Thin overlay - 50 to 80 mm (2 to 3 in)• Milling plus thin overlay• Open-graded friction course• Full-depth or partial-depth repairs• Thin, hot-applied surfacing
Rehab & Maint. HMA Overlays 18
Photo of milling
Rehab & Maint. HMA Overlays 19
Structural Deficiencies
• Adversely affect the load-carrying capability of the pavement
• Indicators– Cracking– Distortion (rutting)– Disintegration
Rehab & Maint. HMA Overlays 20
Photo of alligator cracking
Rehab & Maint. HMA Overlays 21
Thickness Design
• Engineering judgment• Deflection• Layer deficiency• Mechanistic
Rehab & Maint. HMA Overlays 22
Subgrade Soil
Base/Subbase
Surface
SUR
SUB
SUR
AxleLoad
Pavement Deflections
Rehab & Maint. HMA Overlays 23
NDT SensorsNDTLoad
Measurement of Surface Deflection
Rehab & Maint. HMA Overlays 24
NDT Load
“Strong”Pavement “Weak”
Pavement
Strong vs. Weak Pavements
Rehab & Maint. HMA Overlays 25
Dynatest FWD
Load
Deflection measuring sensors
Rehab & Maint. HMA Overlays 26
Options for Correcting Structural Deficiencies
• Structural overlay• Preoverlay repair and structural overlay• Recycling and structural overlay• Reconstruction
AASHTO procedure provides an overlay thickness to correct a structural deficiency
Rehab & Maint. HMA Overlays 27
Considerations for Overlays
• Preoverlay repair• Overlay materials• Subdrainage• Reflection crack control• Traffic loadings• Pavement widening
Rehab & Maint. HMA Overlays 28
Preoverlay Repairs
• Amount and type depends on– Type of overlay– Structural adequacy– Distress types and severity– Future traffic loadings– Physical constraints– Overall project funding
Rehab & Maint. HMA Overlays 29
Preoverlay Repairs
• Consider trade-offs between– Overlay type– Overlay thickness– Preoverlay repair extent
Rehab & Maint. HMA Overlays 30
Rehab & Maint. HMA Overlays 31
Recommended