THE ROAD SURFACE TREATMENTS ASSOCIATION

Surface Dressing & Micro-Surfacing

Dr Howard RobinsonChief Executive

1www.rsta-uk.org

Surface Dressing Long History of Use

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Performs 2 functions which relate directly to the essential requirements in the European CPD

Safety Skid ResistanceIncreases macro & micro texture with minimum usage of scare high quality aggregate

Durability Preventative Maintenance Seals underlying surface from ingress of water and air

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Surface Dressing

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Single Dressing

Racked-In

Double Dressing

Sandwich Dressing

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Surface Dressing techniques

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Carriageways

Footways

Cycleways

Car parks

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Surface Dressing Applications

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Treatment composition kg/m2

Material Single Dressing

Double Dressing

40mm Asphalt

SurfacingBinder 1.0 1.5 6.0

Aggregate 12.0 21.0 93.0

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Finite Resource ConsumptionFinite Resource Consumption

Comparative Costs and Life

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Type Application /m2+/10%

ExpectedLifeyears

6mmSingleSurfaceDressing Estateroads,ruralareas 1.50 7 10

10&6mmRackedInDressing Urbanroads,quieter 1.80 7 10

14&6mmDoubleSurfaceDressing(relativelynew)

Busyurbanroads,higherstress,gradient,bend

2.20 7 10

Prepatchingadditionalcost Rural,urbanroads 1.00 1.50 n/a

MicroAsphalt14mm MainlyUrbanlocations 3.00 7 12

Microasphalt+regulating+ironworksraised

MainlyUrbanlocations 3.50 4.00 7 12

HighFrictionSurfacing Highstressareas 9 12 5 10

Retexturing bushhammer Anywhereexposedaggregates

2 3 3 5

GilsonitePreservative Anywhere 0.8 1 3 5

AsphaltReinforcementGeocomposites/Geotextiles

Urban,trunkroads 5 8 Increaseslifebyfactorof4

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20Years

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Years

O v era ll cond ition

O vera ll cond ition

G ood

G ood

P oor

P oor

S urface d ressing

S urface d ressing

D e fects v is ib le

P a tch ing

R econstruction

S urface d ressingS urface d ressing

Source : Aspha lt S urfac ings, S teven S t John

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Surface DressingExtending time to structural maintenance

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Work ongoing at University of Nottingham to develop process maps and capture energy data for a range of surface treatments that can then be fed into asPECT

Asphalt Pavement Embodied Carbon Tool

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Carbon Footprint

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Quality ControlQuality Control

Chipping Spread Rate Test

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Binder Spread Rate Test

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Carpet Tile Spray Bar Test

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SpecificationSpecification

SHW Clause 922SHW Clause 922BSEN 12271BSEN 12271

PD6689PD6689

Procurement

Method 1 Specified by end product performance - Cl 922 of SHW

Method 2 Specified by recipe - Cl 919 of SHW

Method 1 defines a product and therefore the Construction Product Regulation applies and BSEN12271

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Clause 922

Thecontractormust... Produceadesigntoachievealevelofperformancee.g.

macrotextureandalsoadesignlife

InstalladressingthatmeetsrequirementsofNHSS13a Provideaqualityplan BecompliantwithBSEN12271 Providea2yrguarantee Provideevidencehisspraytankerandchippingmachinecan

achievethedesiredrateandaccuracyofspread

ProduceaselfcertifiedTAIT

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BSEN 12271 EffectiveinUKfromJanuary2011 PD6689providesUKguidance Specifiesarangeofpropertiesandcategoriestoenableappropriatelimitingvaluestobesetforawiderangeofuses

CEMarkingcurrentlynotmandatoryinUK

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PD 6689 Constituent Materials

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Binders

UnmodifiedbindersmustconformtoBSEN13808emulsions

PMBsareproprietarymaterialsandClauses919and922requirethesetohaveBBAHAPAScertificates

BSEN12271includesameasureofbindercohesion(VialitTest)

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Modified BindersModified BindersVialitPendulumCohesion

Vialit Cohesion BS EN 13588

HA SHW Clause 939

Grades (minimum Peak Cohesion):

Super premium binder 1.4J/cm2

Premium binder 1.2J/cm2

Intermediate 1.0J/cm2

Unmodified* 0.7J/cm2

*threshold level for guidance only

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PD 6689 Aggregates

HD36adviseswhatPSVandAAVtobeusedonasitebysitebasis. ThePSVisrequiredtoensurethedurabilityofskiddingresistance

AggregatesusedinsurfacedressingshouldconformtoBSEN13043

RecommendationsforgradingsofchippingsareinPD66822:2009,Table4

BSEN13043alsorecommendsthat,forsurfacedressing,thefinescontentshouldbef1(i.e.notmorethan1%passing0.063mmsieve)

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PD 6689 Performance Criteria

PerformancecategoriesinPD6689havebeenchosenfromBSEN12271:2006,Table2

TheserecommendationsrelatetheHAUCroadtypestogetherwiththedesignclassificationsfromRN39

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EN 12271:2006(E) - Table 2

Type Approval Installation Trial (TAIT)

TAITsarethemeansbywhichaproducerdemonstratestheabilitytodesignandinstallagrouporfamilyofsurfacetreatmentsmeetingtherequiredperformancecharacteristics

TAITscanalsobeusedasthebasisforCEmarking

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Type Approval Installation TrialRecommended Portfolio

TAITs are the responsibility of the producer and must be verified by a notified body

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Factory Production Control (FPC)

BSEN12271specifiesaFPCsystem aroutetoCEmarking FPCensuresthedesignprocedureisdocumented,therelevantcontrols

andtestsarecarriedoutatminimumfrequencyandrecordsarekept

AllproducersaccreditedtoNHSS13amusthaveaQAsystemwhichmeetsFPCrequirementsandareaccreditedbynotifiedbodies

TheSectorSchemeisarequirementoftheSHWandrequiresproducerstodemonstratethecompetenceoftheirworkforce

ThereisascheduleofsuppliersaccreditedtoNHSS13amaintainedbyLantra

Theattestationofconformityis2+

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Surface Dressing Design Guide

SurfaceTemperatureCategory

RoadHardness

Traffic

Geometry

Chippingproperties

Design Input Data

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Surface Temperature Category

Table 7.2.1 - Approximate Surface Temperature Categories

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Road Hardness Category

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Road Hardness Category

very soft

soft

normal

hard

very hard02468

10121416182022

10 15 20 25 30 35 40

Road surface temperature (C)

P

r

o

b

e

p

e

n

e

t

r

a

t

i

o

n

(

m

m

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Figure 7.2.2 Hardness categories from depth of penetration and road surface temperature for Different Surface Temperature Categories

Category B

Traffic

Table 7.2.3 Traffic Categories

Categories converted from msa to cv/l/d assuming a growth rate of 2% over the design life.

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Geometrics

Gradients

Bends

Junction and Crossings

= STRESS

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Chipping Properties

PSV refer to HD36/06 or Figure 7.3.1.

AAV Not greater than 14

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Other Data Required

General Surface Condition

Season

Shade

Local Traffic

Noise

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Season

Figure 7.3.2 Surface Dressing Season

Tree Shade

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Noise

Increasing texture depth

I

n

c

r

e

a

s

i

n

g

n

o

i

s

e

(

d

B

A

)

6mm

10/6mm

10mm

14/6mm

14mm

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Designing the Dressing

Site Suitability

Sections within the Site

Choosing the Dressing type and Binders

Using the Design Proforma

Selecting the Rate of Spread

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Site Suitability

Figure 8.1 - Effect of Existing Road Surface Characteristics on Achievable Performance Levels

Choosing The Right Dressing

Figure 8.3aSelection of Type of Surface

Dressing for Lightly-Trafficked Sites

Binder Rate of Spread - Table 9.2.2

Racked In Dressing

Relatively low cost and high productivity Extends road life and delays major maintenance spend Reduced traffic management costs and road user costs Efficient use of aggregates/binder and minimal waste Up to 10 year life if properly designed and executed A strategic option for de-carbonising roads Can help to prevent potholing

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Surface DressingBenefits

Better,tougherbinders=betterchipretention Lowtemperatureemulsions(undertrial) Betteremulsionbreakcontrol Bettermobileplant improvedspraying/spreadingaccuracy Closerattentiontoachievinggoodcompaction Closerliaisonwithhighwayauthorities Improvedaftercare BettertrainedoperativeswithCSCScards(SectorScheme13a)

Surface DressingInnovation

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MicroMicro--SurfacingSurfacing

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Micro-Surfacing

Apolymermodifiedcoldpavedasphalt

Thickness6to15mm

Uses

rutfilling/levellingcourse

sealing

fillingpotholes

correctsravelling/bleeding

improvesskidresistance(highervolumeroads)

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Micro-Asphalt Description

Slurrysurfacingintroducedinthelate1950s Primarilyusedasapreservativetreatmentforairfield

runwaystypicalaggregatesizeforslurrysurfacing03mm Slurrysurfacingnowmorewidelyknownasmicroasphaltsor

microsurfacingwithtypically06mmaggregates Microasphaltisamixtureof:

Aggregates(coarseandfine) PMBemulsion Water Cementorhydratedlime Possiblyfibres Chemicalbreaking agent

Theblendofmaterialsisbatchedinsituandlaidbyapurposebuiltselfpropelledmicroasphaltpaver

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Slurry Seal and Micro-Asphalt

Footwayslurrysealismechanicallymixedandhandappliedusingabrushtoprovidesurfacetexture.Nonpolymermodifiedbitumenemulsionandaggregatesizesof03mm

Thincarriagewayandairfieldslurrysealisusuallylaidupto5mmthickusinga03mmaggregateandnonpolymerbitumenemulsion.Laidmechanicallyandissuitableforurbanareasandairfieldtaxiways

Microasphalts firstlayerregulatesandreprofilestheexistingpavement secondlayerprovidesadensesurfacewithgoodtexturedepthand

wetskiddingresistance.

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SLURRY / MICROSURFACING

Composition

Aggregates

Mineralfiller

Water

Bitumenemulsion

Fieldcontroladditive

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Aggregate selection

Strong,durable

100%crushedparticles

Typeofrock

Reactivityoffines critical!

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Aggregate Gradation

Sieve size mm

Slurry Micro- surfacing

5.0 100 100 70-90 2.36 95-100 75-100 45-70 1.18 70-95 55-90 28-50 .600 55-75 35-70 19-34 .300 30-50 20-45 12-25 .075 5-15 5-15 5-15

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Mineral Fillers

Portlandcement

Hydratedlime

Modifyflow&settingcharacteristics

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Bitumen Emulsion Selection

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Polymer

Purposes

reducestemperaturesusceptibility

improvesstiffness

Types

latex(liquid)

solids

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Field Control Additive

Affectsbreaktime

temperature&aggregatereactivity

Typeandamount

amines(0.1%)

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Surface Curing

Mixtime

timeremainingfluid(30180s)

Settime

expulsionofclearwater&initialdevelopmentofcohesion

Traffictime

sufficientcohesionfortraffic(20minto4hrs)

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Mix Design Criteria

Mixingtests

Cohesiontest

Testsforbindercontent

Performancerelatedtests

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Mixing & Cohesion Tests

Mixtime&settime Handmixedfor30s

Partpouredout.Clearwaterexuded settime

Partstirreduntilstiff mixtime

Cohesiontest Rolledintoball&droppedonfloor

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Tests For Binder Content

Wettrackabrasion(WTAT) BS434aggregatetest(max500g/m)

Loadedwheeltest

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Site Selection Client Side

Highwayclientslooktomicrosurfacingtoimprove:

Appearance coveringsurfacedefects Profiling regulationofthesurface SkidResistance replacescontactsurface SubsurfaceProtection sealingtheroadagainstwateringress

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A Potential Micro-Surfacing Site

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Micro-Asphalt Paver

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WATER

BITUMEN

AGGREGATE

SPREADER BOX

Computer Controlled Batching

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Applied through the Spreader Laying box

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Compaction using a Pneumatic Tyre Roller (PTR)

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After Care

Readyfortrafficafter20minutes Sweepafter24hours RaiseIronworknextday Applyroadsafetymarkingsafter72hours Removetrafficmanagementsigns

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Slurry-Micro SurfacingApplications

Carriageways

Footways

Cycleways

Car parks

Playgrounds

Airfield runways

Reservations and Islands

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Benefits

Restorationofinstantaneousskiddingresistanceandtexturedepthlevels

Quickinstallation,withminimumdisruptiontotrafficflows

Environmentallyadvantageouswithlittleornotoxicemissionsandnoheatenergyrequired

Financialcostbenefits

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BSEN 12273 Micro-Surfacing

UK guidance contained in PD 6689 BSEN 12273 will be implemented in UK in

January 2011 By that time all contractors must have in place:

BSEN ISO 9001 QA systems, FPC, TAITs UK specification controlled by SHW Cl.918

contractors must be compliant with Sector Scheme 13b

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Specification Requirements

Aggregates to BS EN 13043 Binders to BS EN 13808 Cationic Bitumen

Emulsions Mix design declared by producer 1 year after installation:

visual assessment of defects surface macro-texture

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BS EN 12274 Test Methods

1. Sampling

2. Residualbindercontent

3. Consistency mixdesign

4. Cohesionofmix mixdesign

5. Wearing(wettrackabrasion) mixdesign

6. Rateofapplication

7. Shakingabrasion(binder/aggregateaffinity)mixdesign

8. Visualassessment

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Clause 918

Contractordesign RegistrationtoSectorScheme13B TAITtoBSEN12273 Aggregatemin.PSV&max.AAV(FI20 omitted) Performancerequirements

Assessmentofdefects&macrotexture 2yearguarantee(macrotextureinitially,1&2years) Normally1yearfornontrunkroads

Specifieshowtoexecutetheworks BBAHAPAScertificationformodifiedbindernolonger

required Bondcoatspecified

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Notes for Guidance on Clause 918

Clause 942 thin surfacing applicable to micro-surfacing for roads carrying > 250 cv/l/d or allowing speeds > 60 mph

Categories given for visual assessment of defects from lightly trafficked roads (Cat. 1) to dual

carriageways (Cat. 4)

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Performance RequirementsRequirement Unit Category

0 1 2 3P1 bleeding, etc. % NPD 8 2 0.5

P2 delamination, aggregate loss, etc.

% NPD 8 2 0.5

Macrotexture mm NPD 0.2 0.4 0.6

Noise (macrotexture) mm Declared maximum

ConstituentsBinder cohesionAggregate PSV

Aggregate micro-Deval

J/cmDeclared class/category

(AAV in UK)Slurry type Defined by maximum aggregate

size & binder type

Design Manual for Roads and BridgesVolume 7 Section 5 Part 2 HD37/99

SHW Series 900

Clause 918 - Slurry Surfacing

Clause 919 - Surface Dressing Recipe

Clause 922 - Surface Dressing Performance

Clause 927 - Micro-surfacing

EN 12271 Surface Dressing (FPC + test methods)

EN 12273 Slurry-Micro Surfacing (FPC + test methods)

PD6689: 2009 Surface Treatments

NHSS 13a Surface Dressing and 13b Slurry-Micro Surfacing

Road Note 39 and RSDA Code of Practice

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Guidance

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THANKS FOR LISTENING!

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