1. Pervious Concrete: Unique Benefits
4/12/2017
Pervious Concrete: Unique Benefits
Liv Haselbach
Associate Professor
Civil and Environmental Engineering
Washington State University
Associate Director: CESTiCC
Center for Environmentally Sustainable Transportation in Cold Climates
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2. What is Low Impact Development?
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What is Low Impact Development?
Land development that mimics the natural hydrological and other natural cycles…. Typical practices include: Vegetated ‘green’ roofs Bio-retention cells (raingardens) Permeable pavements Permeable pavements include: Porous asphalt Permeable pavers Pervious concrete Grid and other surface techniques
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3. Permeable Pavement Systems!
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Permeable Pavement Systems!
Surface Infiltration
Underground Storage
Pollutant Removal:
- on top - in ground
- in reservoir - to air?
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4. What are Permeable Pavements?
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What are Permeable Pavements?
Porous asphalt Permeable pavers Pervious concrete Also overlays
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5. What is Pervious Concrete?
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What is Pervious Concrete?
Mixture of :
Coarse aggregate,
Cementitious material,
Admixtures, and
Water.
Carefully controlled amounts of water & cementitious materials are used to create a paste that forms a thick coating around aggregate particles without flowing off during mixing & placing.
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6. How is pervious concrete placed?PC
Cement 1
Aggregate 3 4
Water
1/2
~1/3
Fines 2 ~0
Mixed
Cured 7 days
Compacted & Covered

7. Porosity of Pervious Concrete
Total Porosity Ranges: ~13%-40%
Recommended: ~20-25%
Tortuousity (vertical and horizontal flow)

8. 4/12/2017
Some Benefits
Reduces Runoff Reduces Pollutants Improves Safety Mitigates Heat Island Effect May Decrease Erosion Reduces Road Noise
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9. Heat Island Effect Metal Removal pH
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Recap of Some Studies from WSU
Heat Island Effect Metal Removal pH
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10. Placements in Pullman Valley Playfield Walks Sloan Sidewalk
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Placements in Pullman
Valley Playfield
Walks
Sloan
Sidewalk
Vetmed Circle
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11. Work from Other Locations
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Work from Other Locations
Placement at Iowa State University
Placements in Greenville, SC
Placement in Kent, WA
Laboratory and Modeling Work
Placement near
Salem, OR
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12. Mitigates Heat Island Effect
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Mitigates Heat Island Effect
Source (EPA, 1992)
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13. Heat Island Mitigation
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Heat Island Mitigation
Based on work by Liv Haselbach, Michelle Boyer and Bill Cofer and data from Iowa State University led by Vernon Schaefer and John Kevern of UMKC.
Portions of this material are based upon work supported by the National Science Foundation grant # The opinions, findings and conclusions presented here are those of the authors and do not necessarily reflect those of the research sponsors.
The authors are grateful to the Department of Public Works for the City of Greenville, South Carolina and to Allen Gaither for their assistance in the previous study which provided the field data.
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14. Heat Island Mitigation
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Heat Island Mitigation
According to LEED: Heat Island Mitigation for Pavements can come from: - Shading - Naturally with trees or other vegetation - Artificially with: - Roofs (but should be ‘cool’ roofs) - Appurtenances such as solar cells - Under buildings - Open graded pavements with at least 50% open and vegetated - Highly reflective pavements (Most concretes are highly reflective, but pervious is not)
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15. Heat Island Mitigation
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Heat Island Mitigation
Permeable pavements may have other characteristics beneficial in mitigating the heat island effect, such as: The insulating capabilities of the extensive pore structure Or evaporative cooling from the water stored in the systems.
Unique Structure of Pervious Concrete
Vertical Porosity Distribution (Denser on Top)
More Porous with Depth
Therefore heat will transfer more rapidly through top than through middle and even slower through bottom.
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16. Surface Temperatures
Hot Summer Day Surface Temperatures: Greenville SC
Courtesy: Haselbach, L.M.: Pervious Concrete and Mitigation of the Urban Heat Island Effect, Proceedings, Proceedings TRB Annual Meeting, Wash. DC, Jan. 2009

17. Undersurface Temperatures!
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Undersurface Temperatures!
Greenville SC Measured Temperatures at the Bottom of the Pavement Layers on a HOT Day in July
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18. Iowa State Study Pavement Cross Section and Sensor Placement
Kevern, J., Haselbach, L. and Schaefer, V.R., Hot Weather Comparative Heat Balances in Pervious Concrete and Impervious Concrete Pavement Systems, 2nd International Conference on Countermeasures to Urban Heat Island, September 2009, Berkeley, CA

19. Less Heat Gain After Heat Waves
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Less Heat Gain After Heat Waves
Where:
ΔEpcc=heat gain for traditional concrete system
ΔEpcpc,corr=heat gain for pervious concrete system
Orange filled triangles indicate daytime precipitation
Haselbach, L., Boyer, M., Kevern, J., and Schaefer, V. (2011), Cyclic Heat Island Impacts on Traditional versus Pervious Concrete Pavement Systems, Transportation Research Record Journal of the Transportation Research Board (TRB), No. 2240, TRB of the National Academies. Wash, DC, pp
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20. 4/12/2017
Metal Removal
Removal of High Levels of Dissolved Zinc and Copper BY Pervious Concrete
Acknowledgments
Funding from Washington State Ferries
WSU contributions: Cara Poor, Jerin Tilson, Marc Beutel, Charles Knack, David Yonge, Michael Wolcott and Kirsti McDaniel
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21. Where does the zinc and copper come from?

22. Research Project Objectives
“Average” Levels for roadways
+100 µg/L for zinc
+20 µg/L for copper
We tested for “Hot Spot”
concentrations of 5x
+500 µg/L for zinc
+100 µg/L for copper
Why? These are places of concern such as parking areas, congested expressways, queuing areas, etc., where the concentrations are about five times typical.

23. Dissolved Metal Capture
Dissolved zinc and copper love concrete!
Chemistry Speak – Zinc and copper complexation to hydroxide and carbonate ions.
Initially a rapid surface phenomenon in “channels, nooks and crannies” of pervious paving.
Then potential diffusion into concrete matrix.

24. Experimental Setup and Test Method
Dripped contaminated “rainwater” on pervious concrete cylinders, simulating a ½” rain event.
Fairly fast flow rate, about 3 inch per hour!!!!

25. Zinc Results for Hot Spot Tests
Haselbach, L., Poor, C., and Tilson, J., Dissolved Zinc and Copper Retention from Stormwater Runoff in Ordinary Portland Cement Pervious Concrete, Construction and Building Materials, 53C..
>95%
Average Reduction

26. Copper Results for Hot Spot Tests
Haselbach, L., Poor, C., and Tilson, J., Dissolved Zinc and Copper Retention from Stormwater Runoff in Ordinary Portland Cement Pervious Concrete, Construction and Building Materials, 53C..
>90%
Average Reduction

27. Accelerated Aging Events –Zinc (OPC)
Haselbach, L., Poor, C., and Tilson, J., Dissolved Zinc and Copper Retention from Stormwater Runoff in Ordinary Portland Cement Pervious Concrete, Construction and Building Materials, 53C..

28. Accelerated Aging Events –Copper (OPC)
Haselbach, L., Poor, C., and Tilson, J., Dissolved Zinc and Copper Retention from Stormwater Runoff in Ordinary Portland Cement Pervious Concrete, Construction and Building Materials, 53C.

29. Smaller Carbon Footprint: pH
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Smaller Carbon Footprint: pH ➜
Absorbs CO2 from atmosphere
Carbonation Process
CO2(g) + H2O(l) = H2CO3(aq)
H2CO3(aq) = H+(aq) + HCO3-
HCO3-(aq) = H+(aq) + CO32-(aq)
Ca(OH)2(s) = Ca2+(aq) + 2OH-(aq)
H+(aq) + OH-(aq) = H2O(l)
Ca2+(aq) + CO32-(aq) = CaCO3(s)
Simplified Equilibrium Equation
CO2(g) + Ca(OH)2(s) = H2O(l) + CaCO3(s)
Work with Jon Thomle with help from Rob Borden
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30. pH Methods of Testing Three levels of ambient air restrictions TBC BC
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pH Methods of Testing
Three levels of ambient air restrictions
TBC BC NC
Control Little CO2 Exposure
If Used as an Overlay
Typical Pervious Concrete System
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31. Decline in Exfiltrate pH Levels Deionized Water.
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Decline in Exfiltrate pH Levels Deionized Water.
Reference: Thomle, J. and Haselbach, L. (2011), The Declining pH of Waters Exfiltrated through
Pervious Concrete, ACI SP-282, The Leading Edge of Pervious Concrete, American Concrete Institute
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32. Most applications pH not a concern after 0.5 years.
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pH in Exfiltrate
Most applications pH not a concern after 0.5 years.
(Plus, in pervious concrete systems pH buffered by contact with soil and dissolved minerals.)
Also performed tests with cylinders immersed in water with varying levels of carbonates as in natural waters (rivers, lakes, marine.)
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33. Accelerated Carbonation
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Accelerated Carbonation
Reference: Haselbach, L. and Thomle, J. (2014), An Alternative Mechanism for Accelerated Carbon
Sequestration in Concrete, Sustainable Cities and Society, 12, 25–30.
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34. 4/12/2017
Summary
Pervious concrete provides treatment for dissolved zinc and copper (full system or overlay only)
Pervious concrete systems provide mitigation for the heat island effect
Pervious concrete can have pH benefits…with time.
GO COUGS!!!!!!!!!!!!!!!!!!!!!!
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