integrating structural and hydrologic design in permeable pavement · integrating structural and...

2010 Concrete Sustainability Conference 1 © National Ready Mixed Concrete Association

Integrating Structural and Hydrologic Design in Permeable Pavement

David R. SmithTechnical DirectorInterlocking Concrete Pavement Institute


Pervious, Porous & Permeable Pavements

PerviousPervious PermeablePermeablePerviousPerviousconcreteconcrete

Permeable Permeable interlocking concreteinterlocking concrete

bl f ti

PorousPorous

capable of accepting, finding a way through

PorousPorousasphaltasphalt capable of passing something

(i.e. air/water)

full of pores, capable of being penetrated


Concrete pavers:

ICP

Concrete pavers:ASTM C 9368,000 psi

PICPPICP Impervious pavement

3


No. 8No. 8 Typical bedding, base & subbase stone sizessubbase stone sizes

No. 57No. 57 No. 2No. 2


PICP for Hydrologic and Structural Design

Structural Analysis HydrologicalAnalysis

Structural Analysis HydrologicalAnalysis

Pavement Structure:Type and thickness of

pavement layers

Drainage Design:Drainage features and characteristic

Pavement Structure:Type and thickness of

pavement layers

Drainage Design:Drainage features and characteristicp y

C id h i

p y

C id h iIs the

drainage adequate?

Consider changing• Drainage characteristics

NoConsider changing

Yes

Is the drainage

adequate?

Consider changing• Drainage characteristics

NoConsider changing

Yes

• Thickness of pavement granular layers

• Thickness of pavement granular layers


Structural Design - AASHTO

1993 ME PDG 2004


Structural Design – AASHTO 1993 ⎤⎡ − ti pp

07.8)log(32.2

)1(109440.0

5.1log

20.0)1log(36.9

19.5

0 −×+

++

⎥⎦

⎤⎢⎣

⎡−

+−+×+×= Ri

ti

R M

SN

ppp

SNSZLogW

)1( +SN

W = design traffic load in equivalent single axle loads (ESALs)

Z t d d l d i tZR = standard normal deviateS0 = standard deviationSN = structural number of the pavement

= Σ a * d= Σ ai * diai = structural layer coefficientdi = layer thickness

pi= initial serviceabilitypi initial serviceabilitypt= terminal serviceabilityMR = subgrade resilient modulus (CBR, R-value)


Truck Volumes and AxleWeights Affect Performance (i.e. rutting)

Traffic loads characterized by Equivalent Single Axle Loadsq g

18,000 lb (80 kN) ESALs


Truck Factor = ESAL per TruckLEF: Load Equivalency Factor = axle load( )4

5 Axle Truck

LEF: Load Equivalency Factor = axle load80 kN( )

5 Axle Truck

2 x 80kN (18 kips) 2 x 70 kN (15.8 kips) 50 kN (11 kips)

LEF = = 1 (x2) LEF = = 0.15504

80( )80 480( ) LEF = = 0.6 (x2)70

4

80( )

TF (one pass) = 2.00 + 1.2 + 0.15 = 3.35 ESALs

( )

(

80( )80( ) ( )80( )


AASHTO Typical ESALs by Road ClassAASHTO Typical ESALs by Road Class

Road Class Design ESALsArterial or Major StreetsArterial or Major StreetsUrban 7,500,000Rural 3,600,000Major CollectorsUrban 2,800,000Rural 1,450,000Minor CollectorsUrban 1,250,000Urban 1,250,000Rural 550,000Commercial/Multi-Family LocalsUrban 425,000R l 275 000Rural 275,000


Porous AsphaltPorous Asphalt Pavements for Stormwater Management, NAPA 2008

Traffic LoadingTraffic LoadingMinimum Compacted Minimum Compacted Thickness, in. (mm)Thickness, in. (mm)

p f g ,

Parking – Little or no trucks 2.5 (65)

Residential street – Some trucks

4.0 (100)

Heavy Trucks 6 (150)

S t d PA l ffi i t 0 40 /i

No Base/subbaseThi k G id li

Suggested PA layer coefficient = 0.40 /in.

Thickness Guidelines


Pervious ConcreteHydrologic Design of Pervious Concrete, Leming, PCA & NRMCA

Traffic Traffic LoadLoad

Design Design Axle Axle Load, Load, lblb

RepetiRepeti--tionstions

Pervious Pervious Concrete Concrete Thickness, in. Thickness, in. (mm)(mm)

18,000 lb (80 kN) 18,000 lb (80 kN) Equivalent Single Equivalent Single Axle Loads over 20 Axle Loads over 20

(7 200 d )(7 200 d )lbs lbs (kN(kN))

(mm)(mm) years (7,200 days)years (7,200 days)

Low 4,000 (18)

Unlimited 4 (100) Unlimited( )

Moderate 12,000 (53)

<10/day 6 (150) <14,400

High 18,000 (80)

2 to 3/day 8 (200) 14,400 to 21,600 (80)

Minor or collector streets

18,000 (80)

<100/day Consult design professional

<720,000

No Base/subbaseNo Base/subbaseThickness Guidelines


PICP Typical max. lifetime loads: 600,000 18,000 lb ESALs or TI = 8.5 Permeable Interlocking Concrete Pavements, ICPI 2006g

** Strengthen soil subgrade with crushed stone to full frost depth


Permeable Design Pro Software


Moving ahead…• All use empirical structural design methods• PICP – accounts for truck traffic loads and soil

strengths provides base/subbase thicknessesstrengths, provides base/subbase thicknesses• AASHTO method reasonable for PICP• Open-graded subbase/base – more research p g /

needed Load-deformation relationships

i ld d f 200 S O d lField data for 2004 AASHTO modelStructural contribution of pavement layers (elastic modulus/layer coefficients)

Caltrans – theoretical modeling – full scale tests(?)MnRoad – full-scale PC & PA tests


2 yrs – residential street Oregon

7 -8 yrs container storage New York New construction Minnesota

16


Completely clogged surfaces require restorative vacuum cleaning

17


• d Inspect & vacuum Inspect & vacuum sweep 2x annuallysweep 2x annuallysweep 2x annuallysweep 2x annuallywith standard with standard

equipmentequipmenttt-- no waterno water

Sweeping only equipmentSweeping only equipmentnot effective in removing not effective in removing

di tdi tsediment sediment

Check infiltration in Check infiltration in small areas with watersmall areas with watersmall areas with water small areas with water --Use ASTM C1701 asUse ASTM C1701 asneededneeded 18


Sweeper EffectivenessLeast effective

Regenerative air vacuum sweeper - use 1-2 times/year

TTrue vacuum sweeper – very powerful – restores highlyclogged (neglected) surfaces19


Sediment collects in top ½ - 1 in. (13-25 mm)

True vacuum sweeperpcleans out clogged stone & restores

surface infiltration – refill with clean stone20


Exposed capUS Army Ft. Stewart, Georgia 21


Covered cap

Exposed capExposed cap

22


Winter Maintenance• Snow melts faster – lower risk of iceSnow melts faster lower risk of ice • Surface does not heave when frozen• Use normal plows - dirty snow piles clog surface• Deicing salts okay• Deicing salts okay• Sand will clog system – use

jointing material for traction

23


PICP Inspection ChecklistVacuum surface 1 to 2 times annually, adjust per sediment

loadingloading Replenish aggregate in joints As needed

Inspect vegetation around PICP perimeter for cover & soil stability Annually, repair/replant as needed

Repair all deformationsexceeding 1/2 in. (13 mm) Annually, repair as needed

Repair pavers offset by more than 1/4 in. (6 mm) above/below adjacent units Annually, repair as needed

Replace broken units impairingReplace broken units impairingsurface structural integrity Annually

Check drain outfalls for free flow of water & outflow fromflow of water & outflow from observation well Annually, after a major storm

24


PICP MaintenancePICP MaintenancePICP MaintenancePICP MaintenanceWorkshopWorkshop

Friday, June 4Naval PostgraduateSchoolSchoolMonterey, CA

www bae ncsu edu/www.bae.ncsu.edu/stormwater/training.htm


PICP Installer Technical Certificate CourseResidential & Commercial ConstructionResidential & Commercial Construction

Estimating

Project managementProject management

Maintenance

Include in BMP manuals


Warrenville, IL

integrating structural and hydrologic design in permeable pavement · integrating structural and...

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