- 1.Pervious Concrete Getting Down to the Details Sean Van Delist
Cement Council of Texas
2.
- Pervious Concrete: What & Why?
- Pervious Concrete: How? Design & Construction
- Pervious Concrete: Other Considerations
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:
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- Reduce Stormwater Runoff (Quantity)
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- Clean Stormwater (Quality)
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- Replenish the water table/ aquifers
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- Allow for Rain water Harvesting
-
- Reduce Urban Heat Island Effect
What Are Permeable Pavements? 7. The Problem to be Fixed
- Pervious Surfaces Absorbs
- Reduces or eliminates run-off
- Removes and destroys pollutants
- Infiltrates into natural soil
-
- Maintains stream base flow
Rainfall
- Impervious Surfaces Deflects
- Flushes pollutants into streams
Rainfall and Run-off 8. Pervious Concrete- 5 basic permitted
uses:
-
- Stormwater runoff reduction (quantity)
-
- Stormwater treatment (quality)
9. Stormwater Quantity 10.
- Soil Filtration & Capture
Stormwater Quality 11. Tree Protection 12. Wetlands Protection
13.
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- 0% credit for vehicular applications
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- 100% credit for pedestrian applications
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- 90% credit for all applications
-
- Required for exceeding maximum parking limits
-
- 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:
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:
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.
- 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
-
- Must accommodate water flow
-
- Design for intentionally weakened subgrade
-
- Use with all soils except sand
Subbase Subgrade 38. Layout/Grade/Slope
- Water should flow vertically
- Can use pavement and ponding zone
- Flat system offers the maximum storage
39. 40. 41. 42. Hydrology- Considerations
- 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
- 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.
- 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
- Different types for different applications
- Overlap based on soil strength
- May add strength to subgrade- compensates for reduced
compaction
48. Separation Layer- Geotextiles
-
- Prevents intermixing of drain rock & subgrade
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- Helps interlock drainrock
-
- Protects permeab ility of subgrade
49. Geotextiles
- TenCate Mirifi 140N most recommended
- 500X may be more useful in clay soils
-
- 100X & 600X also available
50. 51. Rainwater Harvesting- Finley Stadium Chattanooga,
Tennessee 52.
Selection of Drain Rock (base) is important 53. Base
Thickness
- Greater than 6 inches to increase storage
- Greater than 6 inches for freeze-thaw
- Not required in some cases
-
- 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?
- Point-to-Point Aggregate Contact
58. Mixture Proportions
- 2400-2600 lbs.- #89 stone
- 100-400 lbs.- silica sand (#200)
- 400-650 lbs.- portland cement
59. Aggregate
- Texture and Porosity Affected by
- 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:
- 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
- Viscosity Modifying Admixtures (VMA)
- 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.
- Equivalent of 275 to 725 of rain per hour!
Pervious Concrete Properties 69.
- 110 to 130 lbs/ft 3unit weight
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- 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
-
- 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
- Compressive Strength/ Flexural Strength
- Hardened Density and Voids
73.
- Designation: C 1688/ C 1688M 08
- 0.25 cubic ft. bowl & standard proctor hammer
- 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
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- Partially due to nature of materials
- Will always be difficult to match placement conditions
-
- 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?
- 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
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
95. Further Research Materials
- 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
97. Pavement Thickness
-
- 5-6 Residential Driveways
- Consider Conventional Concrete & PICP
-
- Areas with a lot of turning
pervious conventional 98.
- Subgrade & Subbase Properties
- Surface Course Properties
General Pavement Section Thickness Determination 99. Strength
vs. Thickness
- Section strength proportionate to:
- 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
100. Thickness vs. Modulus of Rupture 101. Thickness
- Turns out to be the answer to a number of questions
102. What does this say about strength?
- If you cant have strength
- If you cant affirm strength
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- Dont make the materials stronger
-
-
- Unless you dont need pervious.
103. Finishing: The Typical Process
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.
-
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- Specified # of Technicians, Installers, & Craftsmen
- In addition to this requirement, the placing contractor shall
furnish:
-
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- A minimum of 2 completed projects with addresses
-
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- Unit weight acceptance data
-
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- In-situ pavement test results including void
-
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- 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
-
- Match Placement Method with Mix Design
- Proper Mixing Water (w/c)
- 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 ?
115. Evaporation Control
116. Understand Potential for Evaporation
- Recognize surface area exposure
- Recognize windy conditions
117. Cement Hydration
- Recognize low water traits
- Recognize early hydration process
- 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
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
120. Insufficient Curing 121. Raveling 122. Curing 6 MIL PLASTIC
123. Prepare the Poly
- Unpacked, Unfolded, Rolled
-
- Follow closely behind the placement
-
- Full supply, roll on PVC pipe
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- Full length = slab + 3 feet
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- Full width = slab + 3 feet
124. Loose Edges 125. Gaps 126. Crash and Burn 127.
- Restraint (friction from the foundation)
-
- Ambient (expansion/contraction)
-
- Gradient (may cause curling)
- Changes in moisture content
- Surface drying (may cause curling)
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
- 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 curbs to control stresses
132. Jointing
- Understand limitations of material & construction
methods
133. Control Joints
- 1:1.5 maximum aspect ratio
- Align with joints in plain concrete
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
137. Control Joints- Tooled
- Dont use traditional jointers
138. 139. Control Joints- Saw cut
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
- 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
- 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
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- SS Credit 6.1 Stormwater DesignQuantity Control (1)
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- SS Credit 6.2 Stormwater DesignQuality Control (1)
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- WE Credit 1 Water Efficient Landscaping (1-4)
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- MR Credit 4 Recycled Content (1-2)
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- MR Credit 5 Regional Materials (1-2)
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- Regional Priority Credits for SS 6.1 & 6.2 (1-2)
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- 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]