Performance of Pervious Concrete Pavements Marty Wanielista, Manoj Chopra, Matt Offenberg Joshua Spence and Craig Ballock

Stormwater Management AcademyUniversity of Central FloridaOrlando, FL 32816wanielis@mail.ucf.edu

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

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

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

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

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

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.

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?

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

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

Construction Specifications

Appropriate mix proportions

+/- 5 lbs/CF of design unit weight

Discrepancies are generally related to water content

Too much water – reject load

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

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.

Proposed Design Section (Preliminary)

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.

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

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

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

Embedded Single Ring Infiltrometer

11-5/8”

11-Guage Steel

Subsoil

Pervious Concrete

Core

20”

6”

Embedded Single Ring Infiltrometer

11-5/8”

11-Guage Steel

Subsoil

Pervious

Concrete

Core20”

6”

Advantages

1. One dimensional flow (no horizontal flow between pavement and soil)2. Representative of site existing conditions assuming same soil types, and concrete conditions.

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

Results of UCF Embedded Ring TestsTest Location Test Date

Volume of Rainfall (in)

Infiltration Rate

(in/hr)*Core A 1/19/05 1.94 2.40

Core B 1/19/05 1.49 2.41

Core C 1/03/05 2.27 2.51

Core A 1/20/05 0.85 1.16

Core B 1/20/05 0.89 1.21

Core A 1/21/05 0.93 1.03

Core B 1/21/05 1.03 1.45

Core A 1/25/05 1.37 1.48

Core B 1/25/05 1.21 1.45

* System or concrete core plus soil infiltration rates

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.

Strength Tests

ID Diameter(in)

Weight(lb)

Load(lb)

Strength(psi)

Age(days)

184775 5.99 23.05 65,910 2,339 28

184775 5.99 23.09 66,250 2,351 28

Average 2,345

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

Laboratory Control Chamber

Laboratory Control ChamberPervious Concrete

20”

Plastic Tank

12”

½” PVC Pipe Outlets @ 4’, 3’ & 2’ from top of tank

4’

Subsoil

2’

Field Site Reconnaissance

Vet Office in Sanford FCPA Office in Orlando Sunray StoreAway – Lake Mary Strang Communications – Lake Mary FDEP Office - Tallahassee

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

Field Testing Process

12-in diameter cores Run field tests Collect soil samples Lab work on soil samples Lab test on core infiltration rates

Field Test ResultsCumulative Infiltration Core A-6

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

0 5 10 15 20 25 30 35

Time (min)

Cum

ulat

ive

Infil

ratio

n (m

L)

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 Concrete

Site 2 5.9 (5.3 – 6.6) 5.4 Soil

Site 3 14.4 (2.1 – 22.5) 21.8 Concrete

Site 4 – Area 1 2.1 (0.7 – 4.5) 15.6 Concrete

Site 4 – Area 2 2.9 (0.9 – 4.9) 15.6 Concrete

Site 5 3.7 (1.7 – 5.4) 8.8 Concrete

*Age of concrete varies from 10 to 20 years (except for Site 4 – Area 1, which is 1 yr).

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.

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

Thank You!For additional information:Please see www.stormwater.ucf.eduor call 407.823.4143

Questions?