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:tom_kazmierowski@golder.com