Pavements Materials and the Urban ClimateUrban Climate · Pavements Materials and the Urban...

2010 Concrete Sustainability Conference 1 © National Ready Mixed Concrete Association

Pavements Materials and the Urban ClimateUrban Climate

Kamil Kaloush, Ph.D., P.E.Arizona State University


Sustainable Pavements?

• Performance / Durability• Performance / Durability

– Material / Design

• Safety

• Ride Quality or Comfort

• Life Cycle Cost

• Quality of Life Issues

– Highway Noise

– Air QualityAir Quality

– Urban Heat Island

• Energy Consideration

• Recyclability


Urban Heat Island


ASTER Satellite ImageryINTRODUCTION

Paved surfaces are 40% of the 4urbanized land cover in Phoenix

and contribute to UHI

4

Phoenix Metropolitan Area (11pm at night)


How Much?

l i ( l )Average Hourly Air Temperatures (July 2005) for Sky Harbor Airport (Urbanized), Encanto Park (Green Space), and the City of Maricopa (Rural)

similar peak temperatures

10oF difference at 5am

5

Source: Otanicar et al. 2007


• Canyon Geometry

What are the driving factors?

• Canyon Geometry

• Thermal Properties

• Anthropogenic Heat

• The Urban Greenhouse Effect

Th Eff ti R fl ti it (Alb d )• The Effective Reflectivity (Albedo)

• Reduction of Evaporating Surfaces

d d b l f f

Oke et al. (1997)

• Reduced Turbulent Transfer of Heat


Fundamental Properties

• Albedo, α i i li i lAlbedo, α

• Emissivity, ε

C i C ffi i h heat transfer to

incoming solar radiation

(insolation)

heat transfer to

incoming solar radiation

(insolation)

• Convection Coefficient, h

• Thermal Conductivity, kreflected

emitted

heat transfer to air (convection)

Surface material conduction

reflectedemitted

heat transfer to air (convection)


• Specific Heat, C

• Density ρ

Base material


Base material


• Density, ρ

• Thermal Diffusivity, α,κ


UHI Pavement Mitigation Strategies

• Increase Albedo– Use pigments, light colored aggregates, resin binders

– Surface coatings with nanoparticles

P t (HMA d PCC)• Porous pavements (HMA and PCC)

• Whitetopping strategies

• Reflective Asphalt Pavements Techniques

• Thermal resistant materials• Thermal resistant materials– Aggregates, admixtures, crumb rubber

• Provide cover: trees, solar panels (parking structures)

• To pave or not to pave?p p


Thin and Ultra Thin Whitetopping

Pavement Design Characteristics

Thin and Ultra-Thin WhitetoppingPCC

9December 2, 2008 9


Laboratory Evaluation


U S Green Building Council’s Rating SystemU.S. Green Building Council s Rating System

Leadership in Energy and Environmental Design (LEED™)

LEED Rating Systemg y

• Sustainable Sites

• Water Efficiency

• Energy and Atmosphere

• Materials & Resources

• Indoor Environmental Quality

• Innovation & Design Process

LEED Platinum, Arizona Biodesign Institute at ASU

13


LEED™ and Concrete Pavements

Concrete Pavement may contribute in the following categories…• Sustainable Sites

– Credit 7: Landscape and Exterior Design to Reduce UHI (2 points)Intent – Reduce heat islands to minimize impact on microclimateIntent Reduce heat islands to minimize impact on microclimate7.1 NON-ROOF SURFACES (1 point)• Provide Shade – (<5years) on at least 30% of non-roof impervious surfaces

OR use light colored (reflectance >0.30) for 30% of non-roof– TECH/STRATEGY – PORTLAND CEMENT CONCRETE

OR place a minimum of 50% of parking underground OR open-grid for minimum of 50% of parking lot area

– TECH/STRATEGY – PORTLAND CEMENT OPEN CELLED CONCRETE PAVERS

Other non UHI related creditsOther non UHI related credits…

• Materials and Resources– Credit 2: Construction Waste Management (1-2 points)– Credit 3: Resource Reuse (1-2 points)

C dit R l d C t t ( i t )– Credit 4: Recycled Content (1-2 points)– Credit 5: Local/Regional Materials ( 1-2 points)


Heat Transfer between Pavement and its SurroundingsHeat Transfer between Pavement and its Surroundings

Tools - Modelsf gf g

Solar Radiation,(1−α)q”sol

Convection,h∞(To-T∞)

Irradiation,

Air @T∞

- No. of Pavement Layers- Density- Specific Heat Capacity- Thermal Conductivity- Pavement Layer Thickness

Pavement Layer Interfaceεσ(To4 –T4

sky)

To

- Pavement Layer InterfaceThermal Contact Resistance

- Albedo of Top Layer- Emissivity of Top Layer- Deep Ground Properties

- TemperatureDepth

Pavement

G d (N t l S il)

Conduction to Deep Earth, kgrd ∂T(t)

∂x

Tm

Ti

L- Depth

- Sky View Factor- Solar View Factor

Ground (Natural Soil) Ground)

Initial Condition: @t = 0s, T(0) = TinitialBoundary Condition: @x → ∞ T(t) → T

Tn

Boundary Condition: @x → ∞, T(t) → Tinitial


Alternative Pavement Designs

68

60

64

Pervious*

PCC

48

52

56

Tem

pera

ture

(oC) UTW

HMA

Air Temp

40

44

28

32

36

0 00 2 00 4 00 6 00 8 00 10 00 12 00 14 00 16 00 18 00 20 00 22 00 0 000:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00

Time


City – Wide Analysis


ΔT from UHI Mitigation StrategiesΔT from UHI Mitigation Strategies


Portland Cement Association / American Concrete Pavement Association Study

19


Transportation Research Board

20


TRB on Climate Change

“Reducing transportation-related emissions of carbon dioxide--the primary greenhouse gas--that contribute to climate change and adaptingthat contribute to climate change and adapting to the consequences of climate change will be among the biggest public policy challenges f i th t t ti f i thfacing the transportation profession over the coming decades. “


US GHG Estimates

• Fact: coal is the primary generator of electricity (~50%) in the US

• Electric power generation: ~80% of total GHG p gemissions , EPA 2006

• Transportation Sector: 15-30%

• Pavements???• Pavements???


Pavements and Urban Climate

• Energy consumed by each pavement ?

– Manufacture of raw materials

– Portland Cement Concrete pavement: cement / steel

i h l h l d i i i d– Hot Mix Asphalt pavement: asphalt production, mixing, and drying of aggregates

• Reduction of energy consumption can best be directed in the initial phases of a pavement’s life cycle.p p y

• What are the methods for road designers and transportation officials to model the impact of different pavement types on climate change potentials?

C i th di t CO i i l t d t th diff t• Can we examine the direct CO2 emissions related to the different pavement designs?


Components Used to Model Estimates of Kg CO2 Equivalent

Global Warming Gas

kg CO2 Eq./kgPortland cement Z 42 5

kg CO2 Eq./kg Gravel, at mine

kg CO2 Eq./kg Sand,

at mine

kg CO2 Eq./ kg

Asphalt Cement,

kg CO2 Eq/ kW-hr

Electricity,US average

kg CO2 Eq/ ton-km

Transport, 20 - 28 ton Z 42.5 at mine at mine at refinery US average truck

Carbon dioxide, fossil 0.8048 0.0027 0.0023 0.3817 0.7155 0.2713 Methane, fossil 0.0151 0.0001 0.0001 0.0410 0.0308 0.0084

Carbon monoxide, fossil 0.0008 0 0 0.0010 0.0004 0.0011 Di i id 0 0 0 0 0023 0 0055 0 0012Dinitrogen monoxide 0 0 0 0.0023 0.0055 0.0012

Total Kg CO2 Eq. /kg substance 0.8207 0.0028 0.0025 0.4260 0.7468 0.2821


Model

( ) ( )( )[ ]Y

TpDiMnPnDnWTkmEqkgCOannualTotal ∑ ++

=⋅⋅***1000**

/.2

Where,T = thickness of pavement layer, metersW = width of road, metersDn = density of pavement material, kg/m3Dn density of pavement material, kg/mPn = material production value, kg CO2 Eq. /kg Mn = material mixing value, kg CO2 Eq. /kg Di = distance from material production site to application site kmapplication site, kmTp = transport from production site to application site value, kg CO2 Eq. /kg material-kmY = road life yearsY = road life, years


Kg CO2 Eq. for Production

PCC Production % weight

Kg CO2 Eq./kg

Kg CO2 Eq./Kg

Gravel 0.400 0.0028 0.0011

Sand 0.394 0.0025 0.0010

Portland Cement 0.126 0.8207 0.1034

Total 0.1055

HMA Production

Aggregate 0.950 0.0026 0.0025gg g

Asphalt Cement 0.050 0.4260 0.0213

Total 0.0238

AR Production

Aggregate 0.920 0.0026 0.0024

Crumb rubber 0.016 0.0126 0.0002

Asphalt Cement 0.064 0.4260 0.0273

Total 0.0299


Mixing

• Mixing values (Mn) calculated utilizing CO2 Eq. for the fuels utilized for each of the pavement structures.

• PCC Concrete mixing assumes:g– 355 kilowatt diesel truck running 36 minutes/batch, with 0.76

m3/ batch, which is equivalent to 18420 kilograms /batch.

• HMA mixing: g– for a two-ton asphalt /hr capacity system

– requires 24.6 liters #2 fuel oil and 0.269 cubic meters of natural gas per hour.

• Crumb Rubber:– Shredding of automobile tires consume 950 kW/hr for 2 tons/hr

output of crumb (950 kw/909 kg = 1.045 kW/kg crumb rubber).


Natural gasEmission kg CO2 Eq. kg gas /kjoule kg CO2 Eq./kjoule

CO 1.57 1.12E-07 1.76 E-07CO 1 1 93 E 05 1 93 E 05

Portland Cement Concrete (PCC) Mixing CO2 Eq.

CO2 1 1.93 E-05 1.93 E-051.95 E-05/ kJoule

563745 kJ/ 18371 kg 0.0065Total kg.CO2 Eq. / kg PCC

Hot Mixed Asphalt (HMA) Mixing CO2 Eq.

Mixing Values for PCC and

Natural GasGas kg CO2 Eq. kg gas /106 m3 kg CO2 Eq/106 m3

CO 1.57 288.3 450CO2 1 192200 192200CH4 21 36.8 774

HMA 4

N2O 310 22.7 7050

207436 kgCO2 eq./106m3

2.56 m3 nat. gas/2000 kg

0.00027#2 F l Oil

kg.CO2 Eq. / kg #2 Fuel Oil

Gas kg CO2 Eq. kg gas /103 liter kg CO2 Eq/103 literCO 1.57 0.599 0.9CO2 1 2624.5 2624.5CH4 21 0.0062 0.1N2O 310 0.19 58.9

2684.4 kg CO2 Eq. / 103 liter24.6 liters fuel oil/ 1000 kg

0.0663Total kg.CO2 Eq. / kg HMA


Summary

Pavement CO2

equivalencyDn

Kg / m3

PnKg CO2

TpKg CO2

MnKg CO2equivalency

valuesKg / m Eq./kg Eq./kg - km Eq./kg

Sand 1600 0.0028 0.0002821 0G l 1800 0 0025 0 0002821 0Gravel 1800 0.0025 0.0002821 0

Aggregate 1700 0.0026 0.0002821 0PCC 2403 0 1055 0 0002821 0 00650PCC 2403 0.1055 0.0002821 0.00650HMA 2275 0.0238 0.0002821 0.06630AR 2035 0.0299 0.0002821 0.07230


ExampleRoad Life (years)Road Life (years)

AR 2.5-in, Base 6-in 10UTW 2-in, HMA 2-in, Base 6-in 15

HMA 4-in, Base 6-in 10


Road Life (years)

Example

AR 2.5-in, Base 6-in 10UTW 2-in, HMA 2-in, Base 6-in 20

HMA 4-in, Base 6-in 10

31


Concluding Remarks

• Pavements play a role / have impact on the urban climate.

• Appreciate the complexity of various designs.

U d d d d i d• Understand your data sources and input needs.

• There is no one pavement design and type that fits all!

• We need more user’s tools


Thank You!

[email protected]@asu.edu

Pavements Materials and the Urban ClimateUrban Climate · Pavements Materials and the Urban...

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