Stormwater Management Academy University of Central Florida Orlando, FL 32816

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 wanielis@mail.ucf.edu

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 – • Design Section • Infiltration Rate Performance • 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) • Advantages - • 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 TestMethod 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. Pervious Concrete Core 6” 20” Subsoil 11-5/8” 11-Guage Steel Embedded Single Ring Infiltrometer

22. Pervious Concrete Core 6” 20” Subsoil 11-5/8” 11-Guage Steel Embedded Single Ring Infiltrometer • 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 D3385-03 (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 12-20 in/hr

24. Results of UCF Embedded Ring Tests * 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

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

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. Field Test Results *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.eduor call 407.823.4143Questions?