Pavement Maintenance IIPart 1a: SurfaceTreatments

Objective

Investigate types of surface treatments and where they are most beneficial.

Surface Treatments:PurposeTypically used to:Seal cracksWaterproof surfaceImprove frictionImprove rideabilityRejuvenate surface

Candidate for?

Surface TreatmentsTypesFog SealSlurry SealChip SealCape SealScrub Seal

Fog SealLight application of diluted, slow-setting asphalt emulsion without aggregate cover.DescriptionPurposeSeal pavementInhibit ravelingEnrich hardened/oxidized asphaltProvide delineation with shoulder

Fog Seal BenefitsSeals small cracks & surface voidsPrevents raveling of chip sealsPrevents snow plow damageDarkens new chip seals

Fog SealDistress TypeFatigue CrackingLinear & Block CrackingStable RuttingRavelingFlushing/BleedingRoughnessFriction LossMoisture DamageShovingExtent of ProblemMinorMajorFeasibleNot AppropriateFeasibility

Fog SealDistress TypeFatigue CrackingLinear & Block CrackingStable RuttingRavelingFlushing/BleedingRoughnessFriction LossMoisture DamageShovingExtent of ProblemMinorMajor

Fog SealA fog seal is one of our least expensive tools to use and also one of our least used tools. It consists of the following steps:Clean the pavement surface.Then clean it again!Provide for traffic control.Spray the liquid asphalt.After allowing for cure time blot up any puddling.

Fog Seal

Fog SealMost common product used: CSS-1 diluteCost for CSS-1 dilute in Boise: $112.00 per ton.Cost to apply a fog seal: $0.10 to $0.20 per square yardA maximum of a three year life

Slurry SealMixture of well-graded aggregate and slow setting asphalt emulsionDescriptionPurposeSeal surface cracks.Correct raveling/oxidation.Fill minor surface irregularities and restore friction.Good application to use in subdivisions where curb exposure is an issue.

Slurry SealDistress TypeFatigue CrackingLinear & Block CrackingStable RuttingRavelingFlushing/BleedingRoughnessFriction LossMoisture DamageShovingExtent of ProblemMinorMajorFeasibleNot AppropriateFeasibility

Slurry SealDistress TypeFatigue CrackingLinear & Block CrackingStable RuttingRavelingFlushing/BleedingRoughnessFriction LossMoisture DamageShovingExtent of ProblemMinorMajor

Slurry SealA slurry seal utilizes an emulsified asphalt and a small aggregate that is mixed through a mobile pug mill and then is squeegeed onto the pavement. It consists of the following steps:Clean the pavement surface.Work is normally performed under a road closure.Apply the slurry seal.Wait for cure time. (Usually about???)

Slurry Seal

Slurry Seal

Slurry SealMost common seal used: Type II (1/4-10)Cost to apply: $0.85-$1.20 per square yard.Has an average of a five to ten year life.Should seal cracks prior to applying slurry seal.Requires very clean rock.

Chip SealApplication of asphalt and aggregate chips rolled onto the pavementPurposeSeal pavementEnrich hardened/oxidized asphaltRetard reflection cracking on HMA overlaysImprove surface frictionDescription

Chip SealDistress TypeFatigue CrackingLinear & Block CrackingStable RuttingRavelingFlushing/BleedingRoughnessFriction LossMoisture DamageShovingExtent of ProblemMinorMajorFeasibleNot AppropriateFeasibility

Chip SealDistress TypeFatigue CrackingLinear & Block CrackingStable RuttingRavelingFlushing/BleedingRoughnessFriction LossMoisture DamageShovingExtent of ProblemMinorMajor

Chip SealA Chip Seal provides a little heavier seal and consists of a spray applied liquid asphalt and then rock added to it. A typical Chip Seal consists of the following steps:Clean the pavement surface.Provide for traffic control.Spray the liquid asphalt.Apply the rock into the asphaltRoll with pneumatic rollers.Sweep loose rock up.

Chip Seal

Chip SealMost common product used: Polymer modified emulsion.Cost for emulsion in Boise: $160.00 per ton.Cost to apply a chip seal: $0.90 to $1.40 per yard.A typical life of 7 to 12 years.

Chip Seals--Rules of ThumbDont use on bleeding or rutted pavementsPre-fog seal any new patchesUse clean chipsWait for warm weather (>70F)Spread chips immediately behind emulsion sprayRoll slowly (walking speed) with rubber roller

Cape SealCombination of a chip seal, a slurry seal and usually a crack seal application. Good process to use where curb exposure is a concern.

Cape SealClark Co 1993

Macro SealingApplication of asphalt and aggregate chips rolled onto the pavementSingle machine appliedEliminates distance between distributor and chip spreaderSame results as a chip seal

Macro Surfacing

Scrub SealApplication of sand or small-sized aggregate on broomed layer of polymer-modified asphaltPurposeFill and seal small cracks and voidsEnrich hardened/oxidized asphaltPreparation for another treatmentDescription

Scrub SealDistress TypeFatigue CrackingLinear & Block CrackingStable RuttingRavelingFlushing/BleedingRoughnessFriction LossMoisture DamageShovingExtent of ProblemMinorMajorFeasibleNot AppropriateFeasibility

Scrub SealDistress TypeFatigue CrackingLinear & Block CrackingStable RuttingRavelingFlushing/BleedingRoughnessFriction LossMoisture DamageShovingExtent of ProblemMinorMajor

Scrub SealDeveloped by ADOTDesigned to arrest light deteriorationFills cracks without the labor intensive work Rejuvenates properties of the old asphalt lost due to oxidation

Scrub Seal - How to applyAsphalt agent applied by distributorScrubbed into the cracks & surfaceSand is then applied over asphalt and scrubbed into cracks & surface again.Rolled with a pneumatic rollerTraffic removes excess sandRoad opened in about 2 hours

Review

Investigate types of surface treatments and where they are most beneficial.

Surface Treatments Types - ReviewFog SealSlurry SealChip SealCape SealScrub Seal

Review cont.2 layers of rock on layer of asphalt60% - 70% aggregate coverageAdjust for existing pavement conditionGo lighter on new AC patchesTake time to calibrateBinder protects road - Chips protect the binderCubicle chips better than flat chipsAlways have clean surface / Equip.

Questions?Surface Treatments

This slide lists some of the specific surface treatment techniques commonly used on HMA-surfaced pavements. Each of these treatments will be discussed in more detail in the following slides.

Multiple chip seals (cape seals).Rejuvenating seals.