1.Pervious Concrete Getting Down to the Details Sean Van Delist Cement Council of Texas

2.

Permeable Pavements

Pervious Concrete: What & Why?

Pervious Concrete: How? Design & Construction

Pervious Concrete: Other Considerations

Questions & Answers

Outline 3. Permeable Pavements: Applying the Technology 4. Porous Pavements Bruce K. Ferguson 5. 6.

Permeable Pavements are pavements that allow the passage of stormwater through the surface course layer.Permeable Pavements can provide the following benefits:

• Reduce Stormwater Runoff (Quantity)

• Clean Stormwater (Quality)

• Cool Stormwater

• Replenish the water table/ aquifers

• Allow for Rain water Harvesting

• Reduce Urban Sprawl

• Protect Trees

• Reduce Urban Heat Island Effect

• Eliminates Ponding Water

What Are Permeable Pavements? 7. The Problem to be Fixed

Pervious Surfaces Absorbs

Stores Water

Reduces or eliminates run-off

Removes and destroys pollutants

Infiltrates into natural soil

• Recharges ground water

• Sustains local ecosystem

• Maintains stream base flow

Rainfall

Impervious Surfaces Deflects

Flushes pollutants into streams

Aggravates flooding

Erodes channels

Ground water declines

Streams go dry in summer

Aquatic ecosystems die

Water supplies insecure

Rainfall and Run-off 8. Pervious Concrete- 5 basic permitted uses:

• Stormwater runoff reduction (quantity)

• Stormwater treatment (quality)

• Tree protection

• Wetlands protection

• Zoning credits

9. Stormwater Quantity 10.

Filtration of TSS

Oxidation

Soil Filtration & Capture

Bioremediation

Stormwater Quality 11. Tree Protection 12. Wetlands Protection 13.

Austin

• 0% credit for vehicular applications

• 100% credit for pedestrian applications

LCRA Highland Lakes

• 90% credit for all applications

San Antonio

• Required for exceeding maximum parking limits

TCEQ- Edwards Aquifer

• Not currently allowed overrechargew/o special consideration

ZoningCredits 14. Other Uses 15. Other Uses 16. 17. Other Uses 18. Pervious Pavement- Its a System.

Properly designed and constructed Permeable Pavement Systems provide aStructural and Hydraulic solutionfor sitework pavement loading conditions, stormwater detention and quality improvement requirements.

19.

Permeable Pavements are pavements that allow the passage of stormwater through the surface course layer.Depending on the permeability of site soils, local hydrological conditions, and stormwater management objectives, the water is then managed in one of three ways:

Full Exfiltration

No Exfiltration

Partial Exfiltration

Permeable Pavements 20. Full Exfiltration Permeable Surface Course Gravel/Stone 40% voids Filter Fabric Curb 21. No Exfiltration Permeable Surface Course Gravel/Stone 40% voids Liner Curb 22. Partial Exfiltration Permeable Surface Course Gravel/Stone 40% voids Filter Fabric Curb 23. Objectives

Three positions influence the decisions.

Producer & Installer Hydrology Structure 24. Surface Course Types: Choosing the Proper Material for the Specific Application 25. Dubai Initiative It is a very good initiative as long as it does not consume too much water, and does not need much maintenance, 26. Considerations

All systems function hydrologically

All systems require some type of maintenance

Match surface course for site conditions:

• Climate

• Type of Traffic

• Quantity of Traffic

27. Decks 28. Mulch 29.

Commonly called Decomposed Granite (DG)

Crushed Granite 30.

Filled with gravel, crushed stone or soil for grass to grow thru

Plastic paving cells 31.

Also known as

Permeable Friction Course (PFC)

Permeable Asphalt 32.

Epoxy, polyurethanes, or other polymers used to bind aggregate or rubber chips together

Polymer cement concretes 33. 34. Pervious Concrete 35. PICP 36. Grid/ Turf Pavers & Grasscrete 37. Main Differences to Consider

Subgrade

• Must accommodate water flow

• Design for intentionally weakened subgrade

Separation Layer

• Use with all soils except sand

Subbase

• gap-graded

• Storage layer

Subbase Subgrade 38. Layout/Grade/Slope

Part of System

• Supports traffic

• Allows water to pass

Water should flow vertically

Minimize horizontal flow

Storage in gravel base

Can use pavement and ponding zone

Flat system offers the maximum storage

39. 40. 41. 42. Hydrology- Considerations

Rainfall Characteristics

Soil Permeability

Stormwater Management Objectives

43. Soil Permeability

ASTMD3385 -09 Standard Test Method for Infiltration Rate of Soils in Field Using Double-Ring Infiltrometer

ASTMD5093 -02(2008) Standard Test Method for Field Measurement of Infiltration Rate Using Double-Ring Infiltrometer with Sealed-Inner Ring

44. Subgrade Soils 45. Subgrade Compaction

Of some debate

Compact to 92 - 95% of modified proctor

Compaction of the subgrade is inversely proportional to its permeability.

Uniformity is more important than compaction percentage

46. Subgrade-Pumping

The forceful displacement of soil and water from beneath the pavement through joints and cracks.

Conditions for pumping:

1.Subgrade soils that will go into suspension

2.Free water between slab and subgrade

3.Frequent heavy wheel loads

insert photo from winpump.ppt 47. Geotextiles

Highly recommended

Different types for different applications

Overlap based on soil strength

May add strength to subgrade- compensates for reduced compaction

48. Separation Layer- Geotextiles

Seperation

• Prevents intermixing of drain rock & subgrade

Confinement

• Helps interlock drainrock

Reinforcement

• Carrys some tensile load

Protection

• Protects permeab ility of subgrade

Filtration

• Allows passage of water

49. Geotextiles

TenCate Mirifi 140N most recommended

• Non- woven polypropylene

• filter fabric

• 6 heavier grades

500X may be more useful in clay soils

• Woven polypropylene

• stabilizer fabric

• 100X & 600X also available

50. 51. Rainwater Harvesting- Finley Stadium Chattanooga, Tennessee 52.

Gradation

Angularity

Hardness

Selection of Drain Rock (base) is important 53. Base Thickness

Typically 6 inches

Greater than 6 inches to increase storage

Greater than 6 inches for freeze-thaw

Not required in some cases

• Minimize root damage

• Native soils highly permeable

54. Storage Capacity

Storage capacity typically governs design

Depends on porosity of pavement, subbase, & subgrade.

1 of pavement with 20% porosity can store 0.20

1 of #57 stone base with 40% porosity can store 0.40

6 pavement on 6 subbase can store 3.6 of rain

Curbs can be used for additional storage (ponding)

(20%) 6 in. + (40%) 6 in. = 3.6 in. (20%) 6 in. + (40%) 6 in. + (100%) 6 in. = 9.6 in. 55. Additional Storage 56. Pervious Concrete: What & Why? 57. Pervious ConcreteWhat is it?

Constituents

• Cement

• Water

• Coarse Aggregates

• Admixtures

Point-to-Point Aggregate Contact

Adhered with Past Bridge

Random Structure

58. Mixture Proportions

2400-2600 lbs.- #89 stone

100-400 lbs.- silica sand (#200)

400-650 lbs.- portland cement

0.27-0.32 w/c ratio

admixtures

59. Aggregate

Texture and Porosity Affected by

• Aggregate Size

• Aggregate Grading

• Aggregate Angularity

• Paving Equipment

Volume of aggregate per cubic yard of concrete is about 27 cubic feet

60. 61. Surface Texture Comparison 3/8 rock or gravel is most common size due to smoothness and appearance 62. Cementitious Quantity

Maintain the void structure

Maintain point to point aggregate contact

Maintain the paste thickness

Adjust the cementitious content to coat the aggregate with .015 inch thickness. 63. Water Content

Water/ Cement Ratio: 0.27-0.32

Contractor Controls Water Content to Match:

• Equipment

• Weather

Water may be added at the jobsite

64. Water and Plasticity

Recognize an unstable paste

Recognize a wet, metallic sheen

Recognize a flat, dull appearance

The cement paste is delicate.If water content or plasticity is too high, the paste falls off the aggregate and sinks to the lower parts of the slab. If it is too low, the paste will dry rather than hydrate. 65. Admixtures

Set Controlling

• Retarders

• Hydration Stabilizers

Viscosity Modifying Admixtures (VMA)

Integral Color

Proprietary Additives- Acrylic/ Latex Polymers

66. Proprietary Systems Acrylic/ Latex Polymers

Ecocreto, Stoneycrete, Magna-Crete, Enviro-Crete, Percocrete, Filtercrete, Leakcrete

Almost any liquid latex or acrylic will work

Increases strength, color steadfastness and COST!

67. An Unnatural Act

Making concrete that includes voids.

Intentionally reducing concrete density.

Knowingly reducing concrete strength.

68.

Void content= 10 25%

Drainage rate =

3 to 8 gal/min/ft 2

Equivalent of 275 to 725 of rain per hour!

Pervious Concrete Properties 69.

110 to 130 lbs/ft 3unit weight

• Corresponds to void content

1000 to 4000 psi strength

• Introduction of small amount of fine aggregate and/ or polymers help can increase strength.

Pervious Concrete Properties 70. 71. Properties Testing- Quality Control

Conventional concrete testing methods do NOT apply

• No/ Low slump concrete

• Compressive/ Flexural strengthtesting of lab & field samples has high variability and less accuracy

Density & Void Content and Field Permeability are only tests for acceptance

other ASTM Standards & Testing Methods are currently under development

72. ASTM C09.49 Standards & Work Groups

Fresh density and void content-C1688

Field Permeability-C1701

Compressive Strength/ Flexural Strength

Hardened Density and Voids

Surface Durability

73.

Designation: C 1688/ C 1688M 08

0.25 cubic ft. bowl & standard proctor hammer

• 20 blows per 2 layers

D ensity=M ass/V olume

Void content ( U )=T heoretical-D ensity T heoretical

Standard Test Method for Density and Void Content of Freshly Mixed Pervious Concrete 74.

Designation: C 1701/C 1701M 09

Standard Test Method for Infiltration Rate of In Place Pervious Concrete 75.

High variability with standard procedures

• Partially due to inconsistent modification of test

• Partially due to nature of materials

Will always be difficult to match placement conditions

Current Proposal

• 4X8 cylinders- 2 layers- 5 drops of proctor hammer

Strength Testing 76. Falling Head Permeability Test 77. Evaluating the Surface Durability Potential of a Pervious Concrete Mixture 78. Raveling- Field Check 79. Pressure Washer Testing?

3000 psi

1 gpm

3-inch separation-nozzle to concrete

80. Unit Weight At the Plant

The unit weight is simply the weight of one cubic foot

Critical in quality control

Unit Weight should be +/- 5 pcf of design

Should be performed at the plant

ASTM C 138 81. Pulling Cores

Larger projects might require cores

Measure thickness

• No <

• No >

Measure Dry Density

• + or - 5 pcf

ASTM C 42 82. Load Test 83. Pervious Concrete: How? Design & Construction 84. How?

Relatively new technology (in Texas)

Few established standards and methods

Little collected data on properties

Design and construct conservatively!

85. Pervious Concrete Truths

You have to select, design, and build it right

You can design it to fail

You can design it to succeed

It requires your knowledge & care

Pervious concrete is distinct and different

Every installation is site-specific

86. Key Tools & Resources 87. 88. Pervious Concrete-Technical Resources 89. 90.

Administered by Texas Aggregates & Concrete Assoc.

Several classes offered annually across the state

Private training classes available upon request

91. National Network

Portland Cement Association

National Ready Mixed Concrete Association

American Society of Concrete Contractors

American Concrete Institute

American Society for Testing and Materials

92. Balance 93. Structural Design Procedures

ACI 522 Chapter 6 AASHTO or PCA if strength falls within limits (usually doesnt)

PCA Pervious Concrete Pavements suggests AASHTO, WinPas, PCAPAV, ACI 325, or ACI 330R, or using flexible

pavement structural numbers

ACI 325.12R and 330.1R tables require minimum flexural strength of 500 psi

Bruce K. Ferguson Porous Pavements p. 420, Six inches probably minimum thickness and Heavier traffic loads require thicker slabs.

We need a proper engineering procedure

94. Further Research NeededDesign and Performance

Field performance studies under heavy traffic

Fatigue relationship for pervious concrete

Performance of aggregate interlock joints over

time (faulting progression)

Feasibility of using dowels diameter, bearing

stress

95. Further Research Materials

Structural grades

Different aggregate gradations

Small amount of fine aggregate

Tradeoff between strength and permeability

96. In the Interim

Increase Attention to Detail

Increase Emphasis on Construction Quality

Reduce Emphasis on Strength

Design Conservatively

97. Pavement Thickness

Minimums

• 4-5 Sidewalks& Trails

• 5-6 Residential Driveways

• 5-7 Parking lots

• 7-9 Commercial Driveways

Consider Conventional Concrete & PICP

• Heavy truck traffic

• High volume traffic

• Areas with a lot of turning

pervious conventional 98.

Traffic:

• Type

• Quantity

Subgrade & Subbase Properties

Surface Course Properties

• Thickness

• Strength

General Pavement Section Thickness Determination 99. Strength vs. Thickness

Section strength proportionate to:

• Square of the thickness

• Material Strength

So, if you want a stronger pavement, you can

• Use a LOT stronger concrete

• Use a little more concrete

If the concrete has to be weaker (and in this case, it does)

• You can make the section as strong by making it thicker

• • A Little thicker

100. Thickness vs. Modulus of Rupture 101. Thickness

Turns out to be the answer to a number of questions

Poor Subgrade?

• Increases Thickness

More traffic?

• Increase Thickness

Heavier Loads?

• Increase Thickness

Lower Flexural Strength?

• Increases Thickness

102. What does this say about strength?

If you cant have strength

• Make it thicker

• • A little thicker

If you cant affirm strength

• Make it thicker

• • A little thicker

If you need strength

• Make it thicker

• Dont make the materials stronger

• • Unless you dont need pervious.

103. Finishing: The Typical Process

Spreading

Strike-off

Compacting

Jointing

Curing

1 2 3 4 5 104.

Each builder has a style; a favorite way to assemble his method, his setup, and his crew. Some will perform their flatwork as though they were building pianos. Others will slap it down, any way that gets them paid. Such is the difference between craftsmen and henchmen. There seems to be room for everyone

• Ken Bunyan (Dave Mitchell) inventor of the Bunyan hydraulic roller screed.

105. Finishing Qualifications

Require a Contractor who has successfully completed the NRMCA Pervious Concrete Contractor Certification Course is required.

• • Specified # of Technicians, Installers, & Craftsmen

In addition to this requirement, the placing contractor shall furnish:

• • A minimum of 2 completed projects with addresses

• • Unit weight acceptance data

• • In-situ pavement test results including void

• • content and unit weight

• • Sample of product

• • Proposed equipment to be used

106. Various Placing Equipment Types 107. Concrete Compaction More Compaction = Less Porosity Strength Increases Porosity Decreases More Compaction 108. 109. Ensuring a Durable Surface- Preventing Raveling

Sufficient Compaction

• Match Placement Method with Mix Design

Proper Mixing Water (w/c)

Preventing Evaporation

• Rapid Placement

• Proper Curing

Limit Traffic and Turning

• tire sheer can loosen the aggregate

• One potential solution is to grind down the pavement surface about half an inch.

110. Compaction of pervious concrete material during placement 111. Jointing and Cross Rolling 112. Edge Thickness & Compaction is Critical 113. Stresses are Greatest at Edges & Corners 114. Edging ?

Some debate

May prevent raveling

May promote raveling

Must be done quickly

Must be done correctly

115. Evaporation Control

Sub base Saturation

Fogging

Evaporation Retarders

• Confilm

• The Bean

Curing- Plastic Sheeting

116. Understand Potential for Evaporation

Recognize surface area exposure

Recognize air humidity

Recognize windy conditions

117. Cement Hydration

Recognize low water traits

Recognize early hydration process

Recognize evaporation

Water / Cement ratio is about the water of conventional concrete.

The low water cement ratio causes hydration to flash.

Normal pervious materials require more mixing.

Batch water and add water must be more closely controlled.

Mixer discharge is slower and may batter the inside of the drum.

118. Cement Hydration Launch

The first fifteen minutes

• Tricalcium Aluminate

The first two hours

• Tricalcium Silicate

The rich cement content and low water content is prone to flash. the hydration, starting during the first fifteen minutes.The clock begins ticking when the ingredients are combined. Load 80% of the water and all the admixtures before introducing the cement and aggregate. 119. Recognize Different Evaporation & Set Characteristics

Drum Mixer

Volumetric Mixer

120. Insufficient Curing 121. Raveling 122. Curing 6 MIL PLASTIC 123. Prepare the Poly

Unpacked, Unfolded, Rolled

• Quick installation

• Follow closely behind the placement

• Full supply, roll on PVC pipe

• Full length = slab + 3 feet

• Full width = slab + 3 feet

124. Loose Edges 125. Gaps 126. Crash and Burn 127.

Shrinkage

Restraint (friction from the foundation)

Temperature changes

• Ambient (expansion/contraction)

• Gradient (may cause curling)

Changes in moisture content

Surface drying (may cause curling)

Service loads

Factors That Influence Slab Cracking (Pavement Stresses) 128.

Rebar, even epoxy coated, rusts away over time

Low-slump, high-void material forms poorly around fiberglass rebar

Dont needreinforcement even with conventional concrete for most pavement applications anyway prepare the subgrade properly and joint it properly to take care of

crack and curl control

Remember that an extra inch of concrete can do much more for you than rebar anyway

Reinforcement? Dowels? 129. Tie Bars? 130. 131. Load Transfer

Edge and corner stresses are greatest

Use Thickened Edges

Use curbs to control stresses

132. Jointing

Best Practices

• Control (contraction)

• Construction

• Isolation

Understand limitations of material & construction methods

Use Common Sense

133. Control Joints

15 typical-20 max.

1:1.5 maximum aspect ratio

1/4D

Align with joints in plain concrete

No need to seal?

134. Effects of Joint Spacing10.0 ft 3.0 ft 3.0 ft 3.0 ft Ultra-thin Slabs Deflect Concrete in Compression Standard Slabs Bend Concrete in Tension 135. Jointing Details 136. Control Joints

Tooled

Saw-cut

137. Control Joints- Tooled

Pizza Cutter

Thin blade, small radius

Dont use traditional jointers

138. 139. Control Joints- Saw cut

Too early= raveling

Too late= ineffective

May hinder hydration

Cut at 7 days???

140. Sealing Joints? Joints dont need to be sealed, but sealant canreduce or eliminate raveling at joints 141. Construction joints

Use thickened section or thickened edges for load transfer issues

If additional load transfer is needed, use traditional pavement

142. 143. Isolation Joints

Not expansion joints

Some debate over use

Proper installation critical to good performance

144. 145. 146. Panels 147. Natural Construction/ Isolation Joints? 148. Transition to Asphalt 149. Header Curb 150. Where Pervious Concrete Abuts Conventional Pavement or Structures 151. Important Points for Design & Construction of Pervious Concrete

Get a soils report

Determine thickness design based on usage, ADTT and soil type.

Determine base thickness based on design storm, soil type and flow concentration

Pay close attention to detail in methods and materials.

Use a contractor with NRMCA certified pervious concrete technicians.

Utilize industry resources they are free!!

152. Pervious Concrete: Other Considerations 153. Striping 154. Integral Color 155. Stamping 156. Stained 157. Pervious Concrete- LEED 3.0 Considerations

May Contribute to:

• SS Credit 6.1 Stormwater DesignQuantity Control (1)

• SS Credit 6.2 Stormwater DesignQuality Control (1)

• WE Credit 1 Water Efficient Landscaping (1-4)

• MR Credit 4 Recycled Content (1-2)

• MR Credit 5 Regional Materials (1-2)

• Regional Priority Credits for SS 6.1 & 6.2 (1-2)

May Detract from:

• SS Credit 7.1 Heat Island EffectNonroof

158. 159. 160. Pervious Concrete Maintenance

Design the installation with minimal exposure to sediment from other areas

Minimize the level of flow concentration

Sweep routinely as you would a parking lot of any other paving material

Set up periodic testing for infiltration capacity if a maintenance agreement is required by the approving agency

161. Prevent Runoff 162. Prevent Debris from Washing Onto Slab 163. Slope Grade Away from Pavement SWALE 164. Grade Pavement High 165. No Adjacent Dirt Parking 166. Islands/Vegetation 167. Routine Maintenance- Litter Removal

Leaf blowers work well if done on a regular basis

Vacuum trucks effective at removing fresh deposited large debris

Sweeping not very effective

168. Routine Maintenance- Litter Removal 169. Vacuum Sweeping 170. Vacuum Sweeping 171. 172. 173. Removing Sediments

Low pressure, high volume water

High pressure water usually not needed

174. Before and After Cleaning 175. Repair Work 176. Questions? For additional information or assistance, Please call or email: Sean Van Delist 210-883-8060 [email_address]