The document discusses the sustainability of concrete pavements, emphasizing the need for a balanced approach that includes economic, environmental, and social considerations throughout the pavement life cycle. It highlights various strategies to enhance sustainability, such as reducing cement usage, recycling materials, and using advanced construction techniques. Additionally, it advocates for the development of sustainability metrics and life cycle assessments to quantify the environmental impacts of pavements.

2. Sustainable Concrete Pavements
• Peter Taylor Ph.D. P.E.
• Thomas Van Dam, Ph.D., P.E., FACI, LEED AP

3. Enhancing the Sustainability of Concrete
Pavements
• What do you mean “Sustainability”
• Concrete impact on sustainability
• Improving Concrete Pavements
• Measurement

4. What’s The Deal With Sustainability?
• I am really getting sick of this word!
• Is it code for environmentalism?
• Is its purpose to simply sell products?
• Is it simply another trough for academics to eat out of?
• Am I just getting old and crabby?

5. In Essence, Sustainability…
5
Defines how we can live well today, while ensuring that
our children, and our children’s children, live as well or
better…
And
Ensures that others have this same opportunity for
themselves and their children?
WWF

6. Let’s Keep It Real and
Let’s Keep It Simple
• Sustainability balances:
• Economic considerations
• Environmental considerations
• Social considerations
• Over the life cycle of the
concrete pavement!

7. The Life Cycle: A Key Concept
• The 'life cycle' includes all phases of a pavement’s
existence including:
• Raw materials
• Construction
• Operations
• Maintenance
• Restoration and
rehabilitation
• Disposal/recycling

8. In Addition…
• Sustainability metrics are being developed and will be
required in the near future
• Already adopted by some US states and local agencies
• A lot of excellent work has been done to assess the
environmental footprint of pavements and more is in
the pipeline
8

9. Consequently
• Engineers are
–Scrambling to respond
–Having to learn a new discipline
–Looking for guidance

10. Why Build Transportation
Infrastructure?
• Our society is built on the ability to move people,
goods and energy
• Food
• Expertise
• Education
• Healthcare
10

11. 11
Which is more sustainable?

12. What Makes a Roadway
More Sustainable?
Getting what we need
• Capacity and Longevity
for the minimum :
• Cost
• Energy & resources
• Pollutants
• Negative impact to society
Simply good engineering
(Getting more for less)
12

13. Enhancing the Sustainability of Concrete
Pavements
• What do you mean “Sustainability”
• Concrete impact on sustainability
• Improving Concrete Pavements
• Measurement

14. • Concrete is the most commonly used building material
on the planet
• Therefore the environmental footprint is significant
14
Why Do We Care?

15. Why Do Materials Matter?
• Cement production is responsible for ~1.5% of U.S. total
CO2 and 5-8% worldwide
• Portland cement is responsible for approximately 90% to
95% of the CO2 and 85% of the embodied energy in
concrete

16. Mehta, CI Feb. 2009
Reducing cement?

17. Cement
• About half of CO2 production is from decomposition of
carbonate rock
• We need alternative calcium sources
• Clinkering efficiency is being increased

18. Reducing Clinker Content
• Supplementary Cementitious Materials
• Mostly fly ash and slag cement
• Can be added at the cement plant
• Blended (ASTM C595)
• Performance (ASTM C1157)
• Can be added at the batch plant

19. Why Add Extra Cement?
Yurdakul, MS Thesis, IA State 2010

20. Concrete Mixtures for the
I-35W Bridge
Component Specified
Strength
(psi)
Cementitious Materials Est.
CO2
(lb/yd3)Total
(lb/yd3)
Portland
Cement
(%)
Fly
Ash
(%)
Slag
(%)
Silica
Fume
(%)
Superstructure 6500 700 71 25 - 4 467
Piers 4000 575 15 18 67 - 85
Footings 5250 < 600 40 18 42 - 235
Drilled Shafts 5000 < 600 40 18 42 - 235
(CI, February 2009)

21. Reducing Fuel for Construction
• Recycle – zero-waste
• Local first – minimize transportation
• Select the materials deliberately
• Understand what is available
• Import only what you need

22. Recycling and Reuse
• Concrete is recyclable
• Recycled concrete aggregate (RCA) can be used in:
• new concrete
• subbase
• granular fill
• On-site recycling reduces
time, energy, pollution,
and costs

23. Other Materials?
Low or Negative Carbon Materials
 Geopolymers
 CeraTech
 Calera
 Others?

24. Enhancing the Sustainability of Concrete
Pavements
• What do you mean “Sustainability”
• Concrete impact on sustainability
• Improving Concrete Pavements
• Measurement

25. Design for All Attributes
Light Colored and Cool
Quiet
Surface Textures
Improved
Fuel Economy
Renewal and Recycling
Lower
Energy Footprint
{
Less Fuel Consumed, Less
Water Used, and Less
Waste Generated During
Construction
Industrial
By-Product Use
Improved Stormwater Quality
Structural Capacity
{
Adapted from Wathne, ACPA
Treat Air Pollution
Aesthetically
Pleasing
Two-Lift
Construction

26. Design
• Design for what you need
• No more and no less
• Don’t sacrifice engineering quality
• Are current pavements over-designed?

27. Design
• Are all designs equally desirable for every
situation?
• Traffic load
• Speed
• Environment
27

28. Long Lasting Systems
• Longevity is fundamental
• Balance up front efforts with maintenance on:
• Reconstruction / repair impacts on consumables, and
pollutants
• Delays to public

29. User Delays
• Impact of time and fuel swamps construction impacts

30. How Do We Make Concrete More
Sustainable?
2-lift construction
 Allows use of otherwise unacceptable
materials
 Allows exposed aggregate finish, reduced
noise
 Allows use of TiO2 or
other expensive
systems

31. Total CO2 Emissions
31
Batching 1.3 tonsTransportation
12.3 tons
Materials 237.1 tons
Batching 1.3 tonsTransportation
11.2 tons
Two-Lift PCC
250 tons/lane-mile381 tons/lane-mile

32. How Do We Make Concrete More
Sustainable?
Pervious concrete
 Appropriate for low speed surface
 Improves
groundwater
recharge
 Quiet

33. How Do We Make Concrete More
Sustainable?
Overlays
 Rapid construction
 Uses equity already paid for
 Extends life of distressed
pavements

34. How Do We Make Concrete More
Sustainable?
High Performance Concrete
 Structurally efficient
 Long lasting

35. How Do We Make Concrete More
Sustainable?
Precast systems
 Good for rapid repair
 Efficient use of materials
35

36. Noise
Concrete pavement surfaces can be as quiet as any
pavement surface
 Longitudinal tining
 Exposed aggregate
 Diamond grinding
 Next Generation
36

37. HMA (painted)
PCC
HMA
HMA (painted)
HMA
Chip Seal
CR-PCC
AR-OGFC
AR-OGFC (painted)
PCC
AR-OGFC
AR-OGFC (painted)
45
50
55
60
65
70
0 0.1 0.2 0.3 0.4 0.5
Albedo
MaximumSurfaceTemperature(
o
C)
110
120
130
140
150
160
MaximumSurfaceTemperature(o
F)
thickness = 30cm (12in)
Surface Albedo and Urban Heat

38. Reflectivity
• Use lighter cement
• Slag cement is light
• Use TiO2 cement or coatings
• Photocatalytic – breaks down volatile organic carbons and
nitrogen oxides
• Very bright white
• Keeps surfaces clean
38

39. What About Operations?
• At least 80% of the embodied energy and emissions
associated with pavements is incurred after the
construction phase
• Social impacts are also sizable
39http://www.purdue.edu/eas/carbon/vulcan/plots.php
CO2 released from fossil fuels

40. Fuel Efficiency
• Pavement roughness has an impact on vehicle operating
costs, especially fuel efficiency
• Studies are indicating a small, but significant,
improvement in fuel efficiency when vehicles are
operating on a rigid pavement
• Over a 30 to 50 year design life, this can be huge
40

41. [Centre d’Energetique de l’Ecole des Mines de Paris]

42. Enhancing the Sustainability of Concrete
Pavements
• What do you mean “Sustainability”
• Concrete impact on sustainability
• Improving Concrete Pavements
• Measurement

43. Why Must We Quantify?
• To prove an improvement is an improvement
• To assess the relative value of change
• To provide incentive for change

44. Trust But Verify
• “Greenwashing” is rampant
• A scientifically-based “toolkit” is needed to assess the
sustainability of all pavements
• Life cycle assessment (LCA) for pavements
is being worked on by a number of groups
• Assessment of social impacts is challenging
• Rating systems are available
44

45. Comparison of Alternatives
1. Alt #1 2. Alt #2
GWP
Human
Toxicity EnergyWaste

46. Life Cycle Assessment
• An LCA compares environmental impacts assignable to
producing goods
• Scientifically-based
• It accounts for the effects of “cascading technologies”
• Conducting an LCA infers that a fair, holistic assessment
is done over all phases of a product’s existence
• Establishing a framework is very important

47. Greenroads Sustainability
Performance Metric
• Greenroads v1.0 was released in January, 2010
• http://www.greenroads.us/
• It is a LEED-type system in which points are assigned to
sustainable practices
• Well documented and thorough
• Active participation from the concrete paving industry is
encouraged
47

48. PCRs, LCAs and EPDs
• Environmental Product Declaration
• Quantifiable environmental data to compare
products
48

49. PCRs, LCAs and EPDs
• Environmental Product Declaration
• Find or prepare a Product Category Rule (PCR)
• Conduct a life cycle analysis (LCA)
• Means we need data and models
• Develop the declaration
• Have it verified by a certified body
49

50. PCRs, LCAs and EPDs
• Product Category Rule
• A set of rules for developing environmental
declarations for similar products
• What information should be gathered
• How that information should be evaluated
• Prepared by consensus group
50

52. 52
Questions?