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Pavement DistressesFlexible Pavement
Sponsored by: Minnesota LTAP Center
Presented by: Michael Marti, P.E.SRF Consulting Group, Inc.
Dan Wegman, P.E.SemMaterials
Various Rating Manuals
• Pavement Rehabilitation:A Guide for Minnesota Cities and CountiesMN LRRB
• Distress Identification for the Long Term Pavement Performance Program SHRP
Identifying Distresses Includes:
• Name• Severity• Amount
“Rate what you see and not what you think.”
Fatigue Cracking
• Causes– Insufficient strength– End of pavement life– Too heavy of loads
• Cures– Remove and replace– Mill and overlay
Thermal Cracking (Transverse)
• Causes–Contraction and
Expansion of Pavement with Changing Temperatures
• Cures–Crack Filling–Full-Depth Reclamation–Thick Overlay
Block Cracking
• Causes– High Void Content– Oxidative Hardening of the AC– Thermal Cracking
• Cures– Crack Filling/Sealing– Seal Coat– Full-Depth Reclamation– Thick Overlay
Edge Cracking
• Causes– Soil Movement Beneath
Pavement
• Cures– Crack Filling/Sealing– Full-Depth Reclamation
Reflective Cracking• Causes
– Existing cracks or joints in the underlying structure
– Concrete slab movements
• Cures– Crack Filling– Extensive Pre-Overlay Repair– Rubblizing– Crack & Seat– Saw & Seal– Interlayer
Slippage Cracking
• Description– U-shaped cracks in areas of braking, turning, accelerating
• Causes– Poor bond between asphalt surface and underlying layer
• Cures– Crack Filling/Sealing– Full-Depth Reclamation
Rutting• Causes
– Low Air Voids• Asphalt content
too high– Smooth, Rounded Aggregate
• Excessive amounts of natural sand
– Excess Dust
• Cures– Remove/Replace 100 mm (4 inches)– Micro-surfacing
Shoving
• Causes– Unstable Mix– Braking, stopping or
accelerating traffic
– Slippage between layers • Cures
– Remove and Replace– Mill and Overlay– Thick Overlay
Bleeding
• Causes– Too high asphalt content
• too rich a plant mix• improperly constructed
seal coat• too heavy prime or tack
coat
• Cures– Sand blot– Micro-surfacing– Seal coat
Polished Aggregate
• Causes– Soft aggregate– Heavy traffic
• Cures– Seal coat– Micro-surfacing– Thin Overlay
Raveling• Causes
– Asphalt binder unable to hold aggregate in place
• dusty aggregates• segregation • low in-place density• aged asphalt binder• Stripping
• Cures– Seal Coat– Micro-surfacing– Thin Overlay
Potholes
• Causes – Raveling of cracks– Moisture damage– Freeze-thaw– Insufficient strength
• Cures– Patch
Patch Deterioration
• Causes– Poor bonding to existing
pavement– Improper compaction– Poor materials– Propagation of
original distress
• Cures– Remove and replace– Re-patch– Assess original distress
Lane to Shoulder Drop off
• Cause– Differences in materials
used for lane and shoulder– Differential settlement– Insufficient compaction of
base
• Cures– Wedge/leveling overlay– Micro-surfacing