at Auburn University Strategies for Design and Construction of High-Reflectance Asphalt Pavements Nam Tran, Buzz Powell, Howard Marks, Randy West and Andrea Kvasnak
at Auburn University
Strategies for Design and Construction of High-Reflectance
Asphalt Pavements
Nam Tran, Buzz Powell, Howard Marks, Randy West and Andrea
Kvasnak
at Auburn University
Outline
• Urban heat island (UHI) effects
• Cool pavements and LEED credits
• SRI and how to measure
What Causes Heat Islands?
Source: www.DigitalWorldTokyo.com
Trap hot air and reduce wind flow
Replace trees with buildings & infrastructures
at Auburn University
How to Reduce UHI?
• More trees
• Reflective and green roofs
• Cool pavements
• Efficient cooling systemsU of Washington
ACROS Fukuoka, JP
Ennis Paint
at Auburn University
How to be “Cool” and Get Awards
• According to LEED, cool pavement strategies include: – Shading hard surfaces– Using high-reflectance materials– Using open grid or porous pavements
• LEED awards:– 1 credit for “New” and “School” projects for
50% coverage using cool pavements– 1 credit for 25%, 2 credits for 50%, and 3
credits for 75% coverage for “Retail” projects
at Auburn University
Solar Reflectance Index (SRI)• A function of reflectance and emittance –
– SRI = 100 for standard white surface– SRI = 0 for standard black surface– Reflectance has profound effect on SRI– More information in ASTM E 1980
• Higher SRI, lower surface temperature
at Auburn University
How to Measure Reflectance
• Field – ASTM E 1918– Equip.: ~ $2,000– Mat: 10 ft x 10 ft
• Laboratory– ASTM C 1549– Equip.: ~ $30,000– Core: 6 in. dia
at Auburn University
0
10
20
30
40
New Old (~ 7 years)Pavement Surface
SR
I (%
)
HMA PCC
Asphalt vs. Concrete
Have similar SRI as they
get older