PROPERTY MANAGEMENT GUIDE:
DRAINAGE AND MAINTENANCE - THE WAY TO PRESERVE PAVEMENTS
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Pavement Premature Failure
“60% of all premature failures are caused by drainage problems.”
-ASHTO
Pavement Structure
Pavement Response to Load
What Water Does
 Reduces
Stiffness by:
- Increased pore pressures that lower internal friction and thus shear resistance
- Buoyancy of particles that reduce effective weight and lowers inter particle friction.
- Expansive soils cause differential heave.
- Frost heave due to freezing and thawing of the pavement.
Effect Of Stiffness on Pavement Response
Fatigue Failure
Sub grade Rutting
Potholing and Collapse
Potholes
Potholes
Water Sources
Mostly from Surface!
- Cracks joints
- Adjoining impermeable areas
- Runoff
- Blocked, cracked drains
- No drainage
- Wrong slopes
Designing for Moisture
- Rainfall and evaporation
- Permeability of surface
- Water table
- Permeability of pavement layers
- Shoulders
- Type
- Seepage from higher ground
- Infiltration
- Freeze Thaw
- Positive Pore Pressure
- Sensitivity of sub grade soils to moisture
Base and Subgrade Drainage
Surface
Most Water comes from the surface
Cracks, holes, seepage from higher ground
Base
- Permeability
- Slope, width
- Free draining preferable
- High density base with asphalt treatment or HMA
- Protect by adequate surface drainage and integrity
Surface
Sub Surface
- Can cause a layer of mud at base subgrade interface.
- Depends on composition- volume change
- Compaction
Sub grade Drainage
Sources:
- Ground water
- Surface water
- Longitudinal drains
- Soil assessment
- Water flows
- Freeze thaw
- Drain materials
Problem Correction
- Dig Outs
- Sealing
- Install sub surface drains
- Assess changes in area use and adjacent area use for drainage.
- Keep existing drains clear
- Correct elevations do not over pave
Rehabilitation Strategies
- Preventing damage
- Maintenance
- Pot hole and crack repair
- Surfacing and Sealing
- Slurry
- Chip Seal
- Hot Mix Patching and overlay
- Asphalt Rubber Membranes
- Cape Seal
- Geo-textiles
Geotextile
Geotextile
Conclusions
- Many pavement failures are due to drainage problems
- These are either due to poor design or changes during the life of the pavement
- Most problems are surface related so preventative maintenance and proper rehabilitation is the key
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