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Sustainability Metrics of PavementPreservation Techniques
Tom Kazmierowski, P.Eng
Outline
Past - What have we learned
Present - Current practices and
improvements
Case Study - PaLATE
Sustainable Future – Challenges
What is Pavement Preservation?
Coordinated approach to pavementmaintenance/rehabilitation:
Planned not reactiveTreatments are performed before theappearance of significant distressesExtends the service life
Preservation vs. Routine Maintenance
Preservation treatments are designed to beproactive, applied while the pavement is still ingood condition and maintains the pavement at ahigh level of service
VersusWorst-first & reactive types of major maintenance
repairs made to existing distressesmost common approach to pavementmaintenance
Strategy Definitions
Preservationplanned strategy to extend the life of the pavementpreserves the system, retards deterioration, and maintains orimproves the functional condition of the system (withoutincreasing structural capacity)
Rehabilitationrenews the life of the pavementwork undertaken to restore serviceability and improve an existingpavement to a condition of structural or functional adequacy
Reconstructionremoval and replacement of the existing pavement structure
Holdingstrategy that prolongs the life of an asset (for a planned period oftime). Strategy employed to maintain acceptable levels offunctionality or safety until full rehabilitation or reconstruction canbe completed.
“Mix of Fixes”Preservation
MicrosurfacingMill 50 mm, Pave 50 mm (Recycled Hot Mix, Warm Mix)Hot In-Place Recycling, chip seals, crack sealing, etc.
RehabilitationMill 50 mm, Pave 90 mm (Recycled Hot Mix)Cold In-Place Recycling and Pave 50 mm
ReconstructionRubblize, granular grade raise, and thick HMA overlaysFull depth reclamation (FDR) and HMA pavingFull depth removal and replacement with new pavementstructure
HoldingHot Mix PatchingThin Resurfacing
Preservation Strategies – Rigid Pavements
Dowel bar retrofit of cracks and joints,Cross-stitching of longitudinal cracksJoint and crack sealing / resealingDiamond grinding to address ride, friction ornoise issuesPartial depth repairsPre-cast concrete pavement repairs
Dowel Bar Retrofit
Cross - Stitching
Joint and Crack Sawing and Sealing
Diamond Grinding
Partial Depth Repairs
Remove and ReplaceDeteriorated SurfaceConcrete
Precast Slab Repairs
Preservation Strategies – Flexible Pav’ts
Thin SurfacingMicro-surfacingSlurry SealChip SealFibre modified Chip SealUltra thin Bonded Friction Course
Crack SealingHot In-place RecyclingWarm Mix Asphalt
Crack Sealing
Typically used toprevent water and
debris from enteringcracks in the HMApavement surface
Thin Surfacings
Typically used to:seal crackswaterproof surfaceimprove frictionimprove rideabilityrejuvenate surface
Slurry sealMicro-surfacingChip seal / DynapatchNovachipFMCSUltrathin (premium sand mix)
Slurry Seal
Descriptionmixture of well-gradedaggregate and slowsetting asphalt emulsion
Purposeseal surface cracksaddress raveling/oxidationfill minor surfaceirregularitiesrestore friction
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Micro-Surfacing
a polymer-modified cold slurry paving system a mixture of dense-graded aggregate, asphalt
emulsion, water and mineral fillers typically 12 mm thick
Chip Seals (Dynapatch)
DescriptionMechanical spraypatching application ofasphalt and single-sizedaggregate chips rolledonto the pavementPurposeseal pavement surfaceenrich hardened/oxidized asphaltimprove surface friction
Ultrathin Bonded Friction Course (Nova Chip)
Descriptiongap-graded,polymer-modifiedHMA placed on aheavy, emulsifiedasphalt tack coat
Purposeaddress surfacedistressincrease surfacefriction
Fiber Modified Chip Seal (FiberMat)Description
FMCS consists of a chip seal applicationincorporating chopped fiberglass strands in the polymermodified emulsion and a covering aggregate layer.
Hot In-PlaceRecycling
(HIR)
New Three-Stage Recycler
Warm Mix Asphalt
DescriptionReduction in the asphaltmixtures temperatures
(~50 °C) while stillachieving adequatecompaction
PurposeLower temperatureReduce fuel consumptionReduce GHG emissions
10 Years Pavement PreservationTreatment Quantities (2003-2012)
Treatment Quantities (m2)Micro-surfacing 7,309,677
Slurry Seal 906,050
Chip Seal 849,178
FMCS 440,641
Ultra-thin 450,223
HIR 324,124
Total10,279,893
Current Practice
Recent improvements in design, materials andconstruction processes have significantlyincreased the benefits of pavementpreservation techniques.Improvements in technology have provided costeffective designs and optimization ofpreservation strategies.
Design Improvements
Comprehensive Construction and Material Specs:OPSS 341 and 369, Crack SealingOPSS 303 and 304, Chip Seal and Surface
TreatmentOPSS 337, Slurry SealOPSS 336, Micro-SurfacingOPSS 332, Hot in-place recyclingOPSS 333, Cold in-place recyclingOPSS 335, CIR with Expanded Asphalt
Available online: http://www.mto.gov.on.ca/english/transrd
Sustainability Concepts within
Pavement Preservation
Towards a Sustainable Future
What is Sustainable Development?
“…. Development that meets the needs ofthe present without compromising the abilityof future generations to meet their ownneeds.”
Towards a Sustainable Future
To achieve sustainability, every corporatedecision should consider the impact of thetriple-bottom-line.
“What are the Social, Economic, andEnvironmental (SEE) Impacts of thedecision”
Variation in Mean Surface Temp and CO2 Concentration
GHG Emissions and Global Warming
Sustainable Pavement Criteria
“ ….safe, efficient, environmentally friendlypavements meeting the needs of present-day userswithout compromising those of future generations”
Pavement preservation technologies address themain criteria for a sustainable pavement:
Optimizing the use of natural resourcesReducing energy consumptionReducing greenhouse gas emissionsLimiting pollutionImproving health, safety and risk preventionEnsuring a high level of user comfort and safety
Energy Used per Lane-Kilometer of Material Placed
Adapted from ‘The Environmental Road of the Future, Life Cycle Analysis’
by Chappat, M. and Julian Bilal, Colas Group, 2003.
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
Hot-Mix Asphalt Emulsion-BasedCold-Mix
Microsurfacing Central PlantRecycled Hot-Mix
with 20% RAP
Cold In-PlaceRecycling with
Emulsion
Ener
gy (M
J/t)
LayingTransportManufactureAggregateBinder
306,000
63,07059,150
206,910
242,100
Case Study
Quantifying the SustainableBenefits of
Pavement PreservationTreatments
versusTraditional Mill and Overlay
Impact Evaluation
PaLATE software -Pavement Life-cycle Assessment for
Environmental and Economic EffectCreated by Dr. Horvath of the University ofCalifornia at BerkleyAssists decision-makers in evaluating the use ofpavement materials in highway construction(both LCC and Environmental Impacts).
Case Study
Three pavement preservation treatmentsare compared to routine “Shave & Pave”:
Mill 50 mm and overlay 50 mm WMA50 mm HIR12 mm Micro-surfacing
VersusMill 50 mm and overlay 50 mm HMA
Quantify Environmental Effects
Using PaLATE model, the following emissions werecalculated and compared for each treatment:Based on typical 2-lane km section of hwy.
Treatments Energy (MJ) CO2 (tonne) NOx (kg) SO2 (kg)
Mill 50mm, Pave 50 mm 749,586 36 264 159
Mill 50 mm, Pave 50 mmWMA 700,015 35 236 148
50 mm HIR 627,646 28 202 127
12 mm Micro-surfacing 105,993 6 37 25
Environmental Benefits
Per 2-lane km, micro-surfacing consumes only 8% ofthe energy, emits approximately 17% of the CO2, 14%of the NOX, and 16% of the SOX and costs 40-50% lesswhen compared to a conventional mill and overlaytreatmentSince the implementation of micro-surfacing contracts,assuming a 7 year life for micro-surfacing and a 10 yearlife for conventional mill and overlay, GHG emissionshave been reduced by:
28,600 t of CO2220 t of NOx130 t of SO2
And saved 659,000 tonnes of aggregates
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Economic Benefits
Over the past 10 years, MTO has constructed7.3 million m2 of micro-surfacing. If a traditionalmill and overlay were performed instead of micro-surfacing over the past 10 years, $59.1 millionmore would have been spent based on initialconstruction costs.From a life cycle costing perspective, the 10 yearannualized cost associated with using mill andoverlay would be $37.2 million more than thecost of micro-surfacing.
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Sustainable Pavements in Canada
Municipal and provincial agencies currentlyuse numerous innovative pavementpreservation technologies that conserveaggregates, reduce GHG emissions, andminimize energy consumptionA key sustainability strategy is to implementthese technologies on a larger scale andencourage their use Canada wide.These technologies support a “zero waste”approach and will assist in meeting our GHGreduction commitments while addressing thetriple-bottom-line (SEE).
What's next?
Current Life Cycle Costing (LCC) includes:Initial, and discounted main/rehab costs and remaining life costsUser costs
We now have the tools to calculate GHG emissionsand energy savings – PaLATE softwareSeveral sustainability rating systems are availableto quantify and encourage pavement sustainabilityWe are moving towards including an environmentalcomponent into LCC (Environmentalbenefits/credits).Insures that the best treatment is selected tobenefit economic, social and environmental needs- a Sustainable Approach.
What are they? Typically, points based rating system
designed to assess the “greenness” ofpavements/infrastructure.
Goal: To provide an assessment of the
sustainability of pavement/infrastructuredesigns and construction for thepurpose of promoting greener practices.
Green Rating Systems
Category Goal Points
Pavement DesignTechnologies
To optimize sustainable designs. These includelong life pavements, permeable pavements,noise mitigating pavements, and pavementsthat minimize the heat island effect.
9
Materials &Resources
To optimize the use/reuse of recycled materialsand to minimize material transportationdistances.
11
Energy &Atmosphere
To minimize energy consumption and GHGemissions. 8
Innovation &Design Process
To recognize innovation and exemplary effortsmade to foster sustainable pavement designs. 4
Maximum Total: 32
GreenPave Categories
GreenPave Overview
Category
PavementTechnologies Materials &
Resources Energy &Atmosphere Innovation & Design
Process
9 Points 11 Points 8 Points 4 Points
Sub-Category
Long-LifePavements Recycled
Content Reduce EnergyConsumption Innovation in
Design
3 Points 5 Points 3 Points 2 Points
PermeablePavements
UndisturbedPavementStructure
GHG EmissionsReduction Exemplary
Process
2 Points 2 Points 3 Points 2 Points
NoiseMitigation Local
Materials PavementSmoothness
Blue font designatessections applicableonly to constructed
pavements
2 Points 2 Points 1 Point
CoolPavements Construction
Quality PollutionReduction
2 Points 2 Points 1 Point
Additional GreenPave ResourcesReference Guide Computer Spreadsheet
Summary
We will better achieve our sustainable pavementgoals through:
Building on current industry/ministry partnerships in thedevelopment of improved specifications anddesign/construction proceduresEncouraging continued innovation by our pavementpreservation contractorsSupporting dedicated research programs to advancethe technologyIncreasing technology transfer to accelerate adoptionof pavement preservation concepts
Conclusions
Pavement preservation solutions satisfy thedefinition of sustainable pavements:
Pavement preservation programs begin withthe concept that the treatments areproactive and they are applied when thepavement is still in relatively good conditionThinner, faster, less disruptive, less contractadministration, less GHG emissions andless energy consumptionWith coordinated pavementpreservation/rehabilitation programs thevalue of the road network will increase
Conclusions
There is an increased focus on sustainable assetpreservation, both at the provincial and municipallevelsPavement preservation and rehabilitationtreatments applied at the right time cansignificantly extend pavement life and result inimproved network performance over timeImplementation of sustainable AM principles andperformance measures are critical to addressinginfrastructure investment requirements andenvironmental stewardship over the long-term
Thank you!
Questions?
Tom Kazmierowski, P. Eng.Senior Consultant
Golder Associates Ltd.Tel: 905-567-4444
Email:[email protected]