Presentation on theme: "Pervious Concrete: Unique Benefits"— Presentation transcript:
1 Pervious Concrete: Unique Benefits 4/12/2017Pervious Concrete: Unique BenefitsLiv HaselbachAssociate ProfessorCivil and Environmental EngineeringWashington State UniversityAssociate Director: CESTiCCCenter for Environmentally Sustainable Transportation in Cold ClimatesTemplate F-circle lt grey
2 What is Low Impact Development? 4/12/2017What 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 techniquesTemplate F-circle lt grey
3 Permeable Pavement Systems! 4/12/2017Permeable Pavement Systems!Surface InfiltrationUnderground StoragePollutant Removal:- on top - in ground- in reservoir - to air?Template F-circle lt grey
4 What are Permeable Pavements? 4/12/2017What are Permeable Pavements?Porous asphalt Permeable pavers Pervious concrete Also overlaysTemplate F-circle lt grey
5 What is Pervious Concrete? 4/12/2017What is Pervious Concrete?Mixture of :Coarse aggregate,Cementitious material,Admixtures, andWater.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.Template F-circle lt grey
6 How is pervious concrete placed? PCCement1Aggregate34Water1/2~1/3Fines2~0MixedCured 7 daysCompacted & Covered
7 Porosity of Pervious Concrete Total Porosity Ranges: ~13%-40%Recommended: ~20-25%Tortuousity (vertical and horizontal flow)
9 Heat Island Effect Metal Removal pH 4/12/2017Recap of Some Studies from WSUHeat Island Effect Metal Removal pHTemplate F-circle lt grey
10 Placements in Pullman Valley Playfield Walks Sloan Sidewalk 4/12/2017Placements in PullmanValley PlayfieldWalksSloanSidewalkVetmed CircleTemplate F-circle lt grey
11 Work from Other Locations 4/12/2017Work from Other LocationsPlacement at Iowa State UniversityPlacements in Greenville, SCPlacement in Kent, WALaboratory and Modeling WorkPlacement nearSalem, ORTemplate F-circle lt grey
12 Mitigates Heat Island Effect 4/12/2017Mitigates Heat Island EffectSource (EPA, 1992)Template F-circle lt grey
13 Heat Island Mitigation 4/12/2017Heat Island MitigationBased 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.Template F-circle lt grey
14 Heat Island Mitigation 4/12/2017Heat Island MitigationAccording 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)Template F-circle lt grey
15 Heat Island Mitigation 4/12/2017Heat Island MitigationPermeable 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 ConcreteVertical Porosity Distribution (Denser on Top)More Porous with DepthTherefore heat will transfer more rapidly through top than through middle and even slower through bottom.Template F-circle lt grey
16 Surface TemperaturesHot Summer Day Surface Temperatures: Greenville SCCourtesy: 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! 4/12/2017Undersurface Temperatures!Greenville SC Measured Temperatures at the Bottom of the Pavement Layers on a HOT Day in JulyTemplate F-circle lt grey
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 4/12/2017Less Heat Gain After Heat WavesWhere:ΔEpcc=heat gain for traditional concrete systemΔEpcpc,corr=heat gain for pervious concrete systemOrange filled triangles indicate daytime precipitationHaselbach, 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, ppTemplate F-circle lt grey
20 4/12/2017Metal RemovalRemoval of High Levels of Dissolved Zinc and Copper BY Pervious ConcreteAcknowledgmentsFunding from Washington State FerriesWSU contributions: Cara Poor, Jerin Tilson, Marc Beutel, Charles Knack, David Yonge, Michael Wolcott and Kirsti McDanielTemplate F-circle lt grey
22 Research Project Objectives “Average” Levels for roadways+100 µg/L for zinc+20 µg/L for copperWe tested for “Hot Spot”concentrations of 5x+500 µg/L for zinc+100 µg/L for copperWhy? 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 4/12/2017Smaller Carbon Footprint: pH➜Absorbs CO2 from atmosphereCarbonation ProcessCO2(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 EquationCO2(g) + Ca(OH)2(s) = H2O(l) + CaCO3(s)Work with Jon Thomle with help from Rob BordenTemplate F-circle lt grey
30 pH Methods of Testing Three levels of ambient air restrictions TBC BC 4/12/2017pH Methods of TestingThree levels of ambient air restrictionsTBCBCNCControl Little CO2 ExposureIf Used as an OverlayTypical Pervious Concrete SystemTemplate F-circle lt grey
31 Decline in Exfiltrate pH Levels Deionized Water. 4/12/2017Decline in Exfiltrate pH Levels Deionized Water.Reference: Thomle, J. and Haselbach, L. (2011), The Declining pH of Waters Exfiltrated throughPervious Concrete, ACI SP-282, The Leading Edge of Pervious Concrete, American Concrete InstituteTemplate F-circle lt grey
32 Most applications pH not a concern after 0.5 years. 4/12/2017pH in ExfiltrateMost 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.)Template F-circle lt grey
33 Accelerated Carbonation 4/12/2017Accelerated CarbonationReference: Haselbach, L. and Thomle, J. (2014), An Alternative Mechanism for Accelerated CarbonSequestration in Concrete, Sustainable Cities and Society, 12, 25–30.Template F-circle lt grey
34 4/12/2017SummaryPervious concrete provides treatment for dissolved zinc and copper (full system or overlay only)Pervious concrete systems provide mitigation for the heat island effectPervious concrete can have pH benefits…with time.GO COUGS!!!!!!!!!!!!!!!!!!!!!!Template F-circle lt grey