• When you build a pavement it starts to deteriorate from aging traffic and water
• If you wait till it has potholes or extensive cracking it is really too late and rehabilitation is required
• If you apply treatments before it happens it can last longer and will cost less!

• Stopping problems before they grow
• Maximizing the life of the pavement structure by PROTECTING it.
• Regular applications of preservation methods

• Timely
• Affordable
• Cost Effective
• Technically Effective

• Repairing problems without reconstruction
• Follow up with preservation treatments

• Structural - Underlying Pavement
• Bonding
• Surface

Structural Failures
	Poor Design Underestimation of traffic Poor Drainage Overloading Poor Materials Poor Construction Practice Failing to take the local climate into account!

Bonding Failure
	Slippage between layers Poor construction practice or conditions Contamination Traffic type, frequency and situation Climate, especially wet

Surface Failure
Pavement underlying Aging Poor Design Poor Materials Traffic Wrong Method

Main Distress Modes

Deformation Cracking Disintegration

• Aging
• Water Damage
• Traffic
• Climate

• Cracks
• Potholes
• Skid resistance loss
• Profile loss
• Water ponding

• Differentiate Where The Failures have Occurred
• Determine Serviceability
• Determine Appropriate and Economic Treatment

• Crack Sealing – waterproofing pavement
• Patching- water proofing improving ride
• Seal Coating- cosmetic surfacing
• Slurry Seal- sealing
• Microsurfacing- sealing
• Chip Seal- sealing
• Cape Seal- sealing surface profile
• HMA overlays- sealing surface profile

• Microsurfacing Rut Filling
• Stabilization-Recycle
• Asphalt Rubber Overlays
• Asphalt Rubber Chip Seals
• Cape Seals

CRACK SEALING

• Cracks are filled with a rubberized hot or cold filler
• This is applied using a heated pot or other injection device
• Cracks are slightly overfilled to allow for shrinkage
• A layer of dust non stick additive or unwashed sand is placed on top to prevent pick up

• It fills cracks creating a water proofing
• Correct product will expand and contract with the crack to maintain sealing in all seasons and under traffic
• Crack sealing is a pretreatment before a surface coat or may be used alone

• Cracks should be low activity like age cracks
• Fatigue cracks require asphalt rubber membranes before subsequent surfacing
• Extensively cracked roads require membrane treatment
• It should be done when cracks are at their widest
• It may be done the year before surfacing
• Hot pour crack fillers are better than cold pour

• This depends on the materials used
• The area to be filled
• The equipment to be used
• Crack filling is often the least expensive option

Crack filling and proper surfacing will last the life of the pavement.

Crack filling alone will last 3-5 years, however other cracks will open up in 6 mths to 1 year.

Injection Patching

Hot Or Cold Mix Patching

• Areas of failed pavement are dug out and filled with hot mix or cold mixed asphalt. A tack coat of emulsion is applied first.
• Potholes that are isolated are filled with a mix of asphalt emulsion and aggregates- injection patching.This is applied using a special machine
• Holes are slightly overfilled to allow for compaction by roller and traffic
• A layer of dust non stick additive or unwashed sand is placed on top to prevent pick up

• Failed pavement may be replaced
• Holes are filled and the pavement waterproofing restored
• Pavement smoothness is improved

Method - Mix Filling
Hole Cut square, straighten edges Tack coat Fill hole Compact Traffic

Method - Injection Patching
Blow out Hole Tack Fill with emulsion aggregate mix Apply thin layer of dry aggregate Traffic

• For deep patches especially where dig outs have occurred in fatigues pavement
• Strengthening and full depth patches
• Repair before surfacing

• Rural roads
• Parking lots
• Shallow patches where water damage is not extensive
• Repair before surfacing

• Injection patching is inexpensive and large areas can be done in a day
• Hot mix patching is the most expansive patching method

Properly patched and surfaced pavements should last as long as the pavement is designed for.

Injection patching alone will last 2-3 years

Hot mix patching alone will last 5-8 years.

SEAL COATING

• A thin application of a mixture of very fine aggregates, fillers and additives mixed with a slow setting asphalt emulsion (coal tar emulsion in some places)
• May be applied by hand or by machine

• Makes a smooth surface for parking lots or footpaths
• Coats and protects the pavement
• Creates a uniform and attractive black finish
• Is not a high speed surface, adds no structural value. It will re-crack.

• Parking Lots
• Driveways
• Private slow speed roads
• Play areas

• Inexpensive cover technique
• Cheap but not long lasting
• Pavement must be sound
• Cosmetic use mainly

On a sound pavement seal coat will last 2-3 years.

SLURRY SEAL

• Slurry is a mixture of graded aggregates, asphalt emulsion, additives and often polymers
• It is applied using a special paver mounted on a truck or self propelled
• Components are metered into a pugmill, mixed and spread on the surface at 1- 1.5 top size stone thick
• Slurry is a hard wearing road surfacing

• Seals minor cracks
• Seals sound but oxidized pavements
• Restores surface texture and skid resistance
• Corrects raveling
• Reduces noise
• Allows overlays where weight restrictions apply
• Improves ride and profile

Application

What Does It Cost?

• USA figures indicate 5-8 years for slurry. Internationally figures of 5-10 years are quoted.
• Jobs on highly trafficked roads are documented up to 15 years on sound pavements.
• Must be used on sound pavements or else another treatment is required like an asphalt rubber seal before the slurry is applied.

CHIP SEAL

• Chip Seals are an application of a binder followed by spreading of an aggregate (single size preferred).
• It may be applied in multiple layers
• It may be applied with a modified asphalt as a crack treatment alone or before a hot mix overlay

• Waterproofs pavement
• Protects underlying surface from aging
• Restores friction
• Eliminates dust
• May be a crack treatment
• Provides a hard wearing surface

Asphalt Rubber Chip Seal after 5 years

• Chip Seals cost depends on the materials and applications used.
• Chip Seal with emulsion is more expensive than slurry seals but hot chip seals-unmodified are less expensive than slurry seals

Chip Seals last 5-8 years depending on the surface they are put on and the binder used.

CAPE SEALS

What is a Cape Seal


Chip Seal Plus a Slurry

• The chip seal creates a waterproof membrane
• Can be a crack treatment
• The slurry gives a smooth hard wearing surface

• Standard Cape 8-12 years
• AR Cape 10 years plus

HOT MIX OVERLAY

• Hot mix is a mixture of a graded aggregate and hot binder.
• This is manufactured in a controlled plant and taken to the job site
• It may be open-graded, gap graded or dense graded

• Provides an running surface of high skid resistance and durability
• Restores surface profile
• Seals (Dense graded)
• In thick layers is a structural- strengthening layer

• HMA is the most expensive method
• It requires a separate plant and extensive application equipment
• In thick ie >35mm layers it is strengthening and is rehabilitation
• In thin layers <35mm is preservation

A thin overlay of <1 inch will last 5-7 years

A thick overlay 7-12 years

• Assess
• Design
• Supply
• Construct
• Follow Up