Integrating Structural and Hydrologic Design in Permeable Pavement David R. Smith Technical Director Interlocking Concrete Pavement Institute

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1 Integrating Structural and Hydrologic Design in Permeable Pavement David R. Smith Technical Director Interlocking Concrete Pavement Institute 2010 Concrete Sustainability Conference 1 National Ready Mixed Concrete Association

2 Pervious, Porous & Permeable Pavements Pervious concrete Permeable interlocking concrete capable of accepting, finding a way through Porous asphalt capable of passing something (i.e. air/water) full of pores, capable of being penetrated 2010 Concrete Sustainability Conference 2 National Ready Mixed Concrete Association

3 Concrete pavers: ASTM C 936 8,000 psi ICP PICP Impervious pavement Concrete Sustainability Conference 3 National Ready Mixed Concrete Association

4 No. 8 Typical bedding, base & subbase stone sizes No. 57 No Concrete Sustainability Conference 4 National Ready Mixed Concrete Association

5 PICP for Hydrologic and Structural Design Structural Analysis Hydrological Analysis Pavement Structure: Type and thickness of pavement layers Drainage Design: Drainage features and characteristic Yes Is the drainage adequate? No Consider changing Drainage characteristics Consider changing Thickness of pavement granular layers 2010 Concrete Sustainability Conference 5 National Ready Mixed Concrete Association

6 Structural Design - AASHTO 1993 ME PDG Concrete Sustainability Conference 6 National Ready Mixed Concrete Association

7 LogW Structural Design AASHTO 1993 p i p t log log( 1) 0.20 pi S0 + SN log( M ) ( SN +1) = ZR R W = design traffic load in equivalent single axle loads (ESALs) Z R = standard dnormal ldeviate S 0 = standard deviation SN = structural number of the pavement = Σ a i * d i a i = structural layer coefficient d i = layer thickness p i = initial serviceability p t = terminal serviceability M R = subgrade resilient modulus (CBR, R-value) 2010 Concrete Sustainability Conference 7 National Ready Mixed Concrete Association

8 Truck Volumes and Axle Weights Affect Performance (i.e. rutting) Traffic loads characterized by Equivalent Single Axle Loads 18,000 lb (80 kn) ESALs 2010 Concrete Sustainability Conference 8 National Ready Mixed Concrete Association

9 Truck Factor = ESAL per Truck LEF: Load Equivalency Factor = axle load 80 kn 5 Axle Truck ( ) 4 2 x 80kN (18 kips) 2 x 70 kn (15.8 kips) 50 kn (11 kips) 80 ( 4 80 ) LEF = ( 80 ) = 0.6 (x2) 70 4 ( ) LEF = = 1 (x2) LEF = = 0.15 TF ((one pass) = = 3.35 ESALs 2010 Concrete Sustainability Conference 9 National Ready Mixed Concrete Association

10 AASHTO Typical ESALs by Road Class Road Class Design ESALs Arterial or Major Streets Urban 7,500,000 Rural 3,600,000 Major Collectors Urban 2,800,000 Rural 1,450,000 Minor Collectors Urban 1,250,000 Rural 550,000 Commercial/Multi-Family Locals Urban 425,000 Rural 275, Concrete Sustainability Conference 10 National Ready Mixed Concrete Association

11 Porous Asphalt Porous Asphalt Pavements for Stormwater Management,, NAPA 2008 Traffic Loading Minimum Compacted Thickness, in. (mm) Parking Little or no trucks 2.5 (65) Residential street Some trucks 4.0 (100) Heavy Trucks 6 (150) Suggested PA layer coefficient i = 0.40 /in. No Base/subbase Thickness Guidelines 2010 Concrete Sustainability Conference 11 National Ready Mixed Concrete Association

12 Pervious Concrete Hydrologic Design of Pervious Concrete, Leming, PCA & NRMCA Traffic Load Design Axle Load, lbs (kn) Low 4,000 (18) Moderate 12,000 (53) High 18,000 (80) Minor or 18,000 collector (80) streets Repeti- tions Pervious Concrete Thickness, in. (mm) Unlimited 4 (100) 18,000 lb (80 kn) Equivalent Single Axle Loads over 20 years (7,200 days) Unlimited <10/day 6 (150) <14,400 2 to 3/day 8 (200) 14,400 to 21,600 <100/day Consult design professional No Base/subbase No Base/subbase Thickness Guidelines <720, Concrete Sustainability Conference 12 National Ready Mixed Concrete Association

13 PICP Typical max. lifetime loads: 600,000 18,000 lb ESALs or TI = 8.5 Permeable Interlocking Concrete Pavements, ICPI 2006 ** Strengthen soil subgrade with crushed stone to full frost depth 2010 Concrete Sustainability Conference 13 National Ready Mixed Concrete Association

14 Permeable Design Pro Software 2010 Concrete Sustainability Conference 14 National Ready Mixed Concrete Association

15 Moving ahead All use empirical structural design methods PICP accounts for truck traffic loads and soil strengths, provides base/subbase thicknesses AASHTO method reasonable for PICP Open-graded subbase/base more research needed Load-deformation relationships Field data for 2004 AASHTO model Structural contribution of pavement layers (elastic modulus/layer coefficients) Caltrans theoretical modeling full scale tests(?) MnRoad full-scale PC & PA tests 2010 Concrete Sustainability Conference 15 National Ready Mixed Concrete Association

16 2 yrs residential street Oregon 7-8 yrs container storage New York New construction Minnesota Concrete Sustainability Conference 16 National Ready Mixed Concrete Association

17 Completely clogged surfaces require restorative vacuum cleaning Concrete Sustainability Conference 17 National Ready Mixed Concrete Association

18 d Inspect & vacuum sweep 2x annually with standard equipment - no water Sweeping only equipment not effective in removing sediment Check infiltration in small areas with water - Use ASTM C1701 as needed Concrete Sustainability Conference 18 National Ready Mixed Concrete Association

19 Least effective Sweeper Effectiveness Regenerative air vacuum sweeper - use 1-2 times/year True vacuum sweeper very powerful restores highly clogged (neglected) surfaces Concrete Sustainability Conference 19 National Ready Mixed Concrete Association

20 Sediment collects in top ½ - 1 in. (13-25 mm) True vacuum sweeper p cleans out clogged stone & restores surface infiltration refill with clean stone Concrete Sustainability Conference 20 National Ready Mixed Concrete Association

21 Exposed cap US Army Ft. Stewart, Georgia Concrete Sustainability Conference 21 National Ready Mixed Concrete Association

22 Covered cap Exposed cap Concrete Sustainability Conference 22 National Ready Mixed Concrete Association

23 Winter Maintenance Snow melts faster lower risk of ice Surface does not heave when frozen Use normal plows - dirty snow piles clog surface Deicing salts okay Sand will clog system use jointing material for traction Concrete Sustainability Conference 23 National Ready Mixed Concrete Association

24 PICP Inspection Checklist Vacuum surface 1 to 2 times annually, adjust per sediment loading Replenish aggregate in joints As needed Inspect vegetation around PICP perimeter for cover & soil stability Repair all deformations exceeding 1/2 in. (13 mm) Repair pavers offset by more than 1/4 in. (6 mm) above/below adjacent units Replace broken units impairing surface structural integrity Annually, repair/replant as needed Annually, repair as needed Annually, repair as needed Annually Check drain outfalls for free flow of water & outflow from observation well Annually, after a major storm Concrete Sustainability Conference 24 National Ready Mixed Concrete Association

25 PICP Maintenance Workshop Friday, June 4 Naval Postgraduate School Monterey, CA www bae ncsu edu/ stormwater/training.htm 2010 Concrete Sustainability Conference 25 National Ready Mixed Concrete Association

26 PICP Installer Technical Certificate Course Residential & Commercial Construction Estimating Project management Maintenance Include in BMP manuals 2010 Concrete Sustainability Conference 26 National Ready Mixed Concrete Association

27 Warrenville, IL 2010 Concrete Sustainability Conference 27 National Ready Mixed Concrete Association