1. Performance of Pervious Concrete Pavements Marty Wanielista, Manoj Chopra, Matt Offenberg Joshua Spence and Craig Ballock
Stormwater Management Academy
University of Central Florida
Orlando, FL 32816

2. Outline of Presentation
Overview
Background and Current State
Objectives of this On-going Project
Research Plan
Progress to Date
UCF Test Site
Field Tests
Discussion

3. Overview
Pervious or No-fines Concrete – mixture of coarse aggregate, Portland Cement, admixtures and water
Increased Porosity due to limited fines and 15-20% air voids
Strong need for Current and Updated Assessment of Pervious Pavements due to new regulations pending for Stormwater Management

4. Overview Issues to be addressed –
Design Section
Construction Methods
Acceptance Criteria
Infiltration Rate Performance
Credit for Replacement of Impervious Area
Our research will initially address –
Credit for Replacement of Impervious Areas

5. Background and Current State
Replacement of Impervious Areas with Properly Designed and Constructed Pervious Paving Surfaces is Desirable
Treating pervious concrete as a system with pavement and sub soil
ACI Committee 522 has been formed to develop Guidelines for the use of Portland Cement Pervious Concrete

6. Historical and Literature Review
PC Pervious Pavements have been used for past 20 years in Areas of Lower Traffic Loads (parking lots, shoulders, airport taxiways, some state and local roads).
Must have suitable
Subsoil Conditions
Groundwater Locations

7. Historical and Literature Review
Field et al (1982) Water Resources Bulletin – detailed information on PP.
Florida Concrete and Products Association (FCPA) – Portland Cement Pervious Pavement Manual (No. 605)
EPA (1999) – Stormwater Technology Fact Sheet on Porous Pavements
Several recent articles from USC and Purdue, as well as UK, Japan and China.

8. FDOT Interests
Need for a permit, or credit (partial or total) for substituting pervious surfaces
Based on Volume of water that can be Stored and allowed to Replenish the Aquifer
Want answers to –
What is design – materials, dimensions, GWT?
What are proper construction methods?
What is the infiltration rate for the system?

9. Advantages and Disadvantages (EPA, 1999)
Recharge to Local Aquifer
Water budget retention and pollution removal
Less need for Storm Sewers
Disadvantages –
Lack of Construction Experience and Expertise
Clogging
Cold Weather Problems

10. Construction Specifications
Specifications for contractor certification, materials and mix design, construction practices, and post construction care
Sources from EPA, California-Nevada Cement Promotions Council PC Specs, and PCI Systems, LLC. PC Specs

11. Construction Specifications
Appropriate mix proportions
+/- 5 lbs/CF of design unit weight
Discrepancies are generally related to water content
Too much water – reject load

12. Construction Specifications
Concrete should be stricken off ¼ to ½ of an inch about the form boards and compacted to level
Compaction – roll with a 10-inch schedule 40 steel pipe
Curing Time – pavement should be covered a minimum of 7 days

13. Construction Specifications
Limit frequency of heavy traffic – e.g. construction vehicles, garbage trucks, etc.
Remove or Limit sources of sediment
Signage such as “ADOPT A LOT”
Curbing should be used to direct infiltrating water downward and to prevent erosion at the edges of pervious concrete slabs.

15. Proposed Design Section (Preliminary)

16. Design and Construction Specifications
Cities of Stuart, Zephyr Hills, Winter Park, and Titusville and the Counties of Citrus, Hernando, Pasco, and Hillsborough have adopted specifications.
Credit is being determined for use by other Cities and WMDs.
A goal is to have 24 cities and counties with pervious concrete code language for pervious concrete.
Contractor Certification will be an Important Factor
Soil Preparation, Curbing, Field Infiltration Tests and Inspections will be Important.

17. How are Pervious Systems Working?
Develop New Embedded Single Ring Test Method to Measure Infiltration rates
Laboratory Testing – Build Two Test Cells at the UCF Stormwater Laboratory Site and a Control Chamber
Field Testing – Four field sites in Central Florida and one in Tallahassee

18. Preparation of Test Cells
Stormwater Laboratory Field Sites
Two 6 ft.x 6ft. x 4 ft. deep Chambers
5 inch thick pervious concrete pavement
One cell has a “reservoir” of 3/8 inch coarse aggregate to increase storage
Soils were Sandy (Type A hydrological) compacted in 8 inch lifts to 92% Standard Proctor to about 104 lb/ft3

20. Development of Embedded Single Ring Infiltrometer
Double Ring Infiltrometer on the surface of Pervious Pavement not Suitable due to Preferred Lateral Migration of Water
Led to Concept of Single Embedded Infiltrometer
Depth of Embedment is an Important Parameter (Initial Assumption = 14 inches including the 6 inches of pavement)
12 inch Diameter (11-5/8” ID) with 11-Guage Steel

21. Embedded Single Ring Infiltrometer
11-5/8”
11-Guage Steel
Subsoil
Pervious Concrete
Core
20” 6”

22. Embedded Single Ring Infiltrometer
11-5/8”
11-Guage Steel
Subsoil
Pervious Concrete
Core
20” 6”
Advantages
One dimensional flow (no horizontal flow between pavement and soil)
Representative of site existing conditions assuming same soil types,
and concrete conditions.

23. Results at Test Cells
Using ASTM D (Double Ring) procedure adapted to embedded Single Ring
Initial Double Ring Tests on Bare Subsoil before Concrete Placement have yielded infiltration rate of 2.6 in/hr
Without compaction, the rate for the soil was in/hr

24. Results of UCF Embedded Ring Tests
Test Location
Test Date
Volume of Rainfall (in)
Infiltration Rate (in/hr)*
Core A
1/19/05
1.94
2.40
Core B
1.49
2.41
Core C
1/03/05
2.27
2.51
1/20/05
0.85
1.16
0.89
1.21
1/21/05
0.93
1.03
1.45
1/25/05
1.37
1.48
* System or concrete core plus soil infiltration rates

25. Preliminary Observations from UCF Test Chambers
Pervious Concrete Pavement and Subsoil System displays Infiltration Rates nearly equal to Subsoil Alone
Infiltration rates of the system are greater than the minimum rates of 1 in/hr used for the design of FDOT retention areas.

26. Strength Tests ID Diameter (in) Weight (lb) Load Strength (psi) Age
(days)
184775
5.99
23.05
65,910
2,339 28
23.09
66,250
2,351
Average
2,345

27. Laboratory Control Chamber
Better “Control”
Address issues such as Clogging and Water Table Impact
The Chamber was Filled with Sandy Soils from UCF Stormwater Lab. (Type A Hydrologic Group )
Filled in 8” lifts to 92% Standard Proctor

28. Laboratory Control Chamber

29. Laboratory Control Chamber
Pervious Concrete
20”
Plastic Tank
12”
½” PVC Pipe 4’, 3’ & 2’ from top of tank 4’
Subsoil 2’

30. Field Site Reconnaissance
Vet Office in Sanford
FCPA Office in Orlando
Sunray StoreAway – Lake Mary
Strang Communications – Lake Mary
FDEP Office - Tallahassee

33. Field Testing Progress
Six cores at Sunray Storaway, Three at Strang Communications, Three at FCPA, Six in Tallahassee, and Three at Murphy Vet Clinic.
Field infiltration tests completed at all locations
Laboratory tests using Control Chamber on-going

34. Field Testing Process 12-in diameter cores Run field tests
Collect soil samples
Lab work on soil samples
Lab test on core infiltration rates

38. Field Test Results

39. Avg. Concrete Rate [in/hr] (Range)
Field Test Results
Test Location
Avg. Concrete Rate [in/hr] (Range)
Avg. Soil Rate [in/hr]
Limiting Factor
Site 1 – Area 1
25.7 (19 – 32.4)
34.5
Concrete
Site 1 – Area 2
3.6 (2.8 – 4.5)
14.8
Site 2
5.9 (5.3 – 6.6)
5.4
Soil
Site 3
14.4 (2.1 – 22.5)
21.8
Site 4 – Area 1
2.1 (0.7 – 4.5)
15.6
Site 4 – Area 2
2.9 (0.9 – 4.9)
Site 5
3.7 (1.7 – 5.4)
8.8
*Age of concrete varies from 10 to 20 years (except for Site 4 – Area 1, which is 1 yr).

40. Conclusions
Proper construction is important (water in mix, curing); Certification program is needed.
Specifications need to be followed for design and construction; Good design practices (curbing, pavement thickness).
Pavement and Subsoil must be treated as a SYSTEM.

41. Conclusions
Infiltration rates are comparable to Stormwater Retention Ponds.
Water storage is directly proportional to the porosity and the depth to the water table. Modeling efforts currently underway

42. Thank You. For additional information: Please see www. stormwater. ucf
Thank You! For additional information: Please see or call Questions?