Pervious Concrete Getting Down to the Details Sean Van Delist Cement Council of Texas
<ul><li>Permeable Pavements </li></ul><ul><li>Pervious Concrete: What & Why? </li></ul><ul><li>Pervious Concrete: How? Des...
  Permeable Pavements: Applying the Technology
Porous Pavements Bruce K. Ferguson
 
<ul><li>Permeable Pavements are pavements that allow the passage of stormwater through the surface course layer.  Permeabl...
The Problem to be Fixed <ul><li>Pervious Surfaces Absorbs </li></ul><ul><li>Stores Water </li></ul><ul><li>Reduces or elim...
Pervious Concrete- 5 basic permitted uses: <ul><ul><li>Stormwater runoff reduction (quantity) </li></ul></ul><ul><ul><li>S...
Stormwater Quantity
<ul><li>Filtration of TSS </li></ul><ul><li>Oxidation </li></ul><ul><li>Soil Filtration & Capture </li></ul><ul><li>Biorem...
Tree Protection
Wetlands Protection
<ul><li>Austin </li></ul><ul><ul><li>0% credit for vehicular applications </li></ul></ul><ul><ul><li>100% credit for pedes...
Other Uses
Other Uses
 
Other Uses
Pervious Pavement- It’s a System. <ul><li>Properly designed and constructed Permeable Pavement Systems provide a  Structur...
<ul><li>Permeable Pavements are pavements that allow the passage of stormwater through the surface course layer.  Dependin...
Full Exfiltration Permeable Surface Course Gravel/Stone 40% voids Filter Fabric Curb
No Exfiltration Permeable Surface Course Gravel/Stone 40% voids Liner Curb
Partial Exfiltration Permeable Surface Course Gravel/Stone 40% voids Filter Fabric Curb
Objectives <ul><li>Three positions influence the decisions. </li></ul>Producer & Installer Hydrology Structure
Surface Course Types: Choosing the Proper Material for the Specific Application
Dubai Initiative “ It is a very good initiative as long as it does not consume too much water, and does not need much main...
Considerations <ul><li>All systems function hydrologically </li></ul><ul><li>All systems require some type of maintenance ...
Decks
Mulch
<ul><li>Commonly called Decomposed Granite (DG) </li></ul>Crushed Granite
<ul><li>Filled with gravel, crushed stone or soil for grass to grow thru </li></ul>Plastic paving cells
<ul><li>Also known as  </li></ul><ul><li>Permeable Friction Course (PFC) </li></ul>Permeable Asphalt
<ul><li>Epoxy, polyurethanes, or other polymers used to bind aggregate or rubber chips together </li></ul>Polymer cement c...
 
Pervious Concrete
  PICP
Grid/ Turf Pavers & Grasscrete
Main Differences to Consider <ul><li>Subgrade </li></ul><ul><ul><li>Must accommodate water flow </li></ul></ul><ul><ul><li...
Layout/Grade/Slope <ul><li>Part of System </li></ul><ul><ul><li>Supports traffic </li></ul></ul><ul><ul><li>Allows water t...
 
 
 
Hydrology- Considerations <ul><li>Rainfall Characteristics </li></ul><ul><li>Soil Permeability </li></ul><ul><li>Stormwate...
Soil Permeability <ul><li>ASTM  D3385 -09 Standard Test Method for Infiltration Rate of Soils in Field Using Double-Ring I...
Subgrade Soils
Subgrade Compaction <ul><li>Of some debate </li></ul><ul><li>Compact to 92 - 95% of modified proctor </li></ul><ul><li>Com...
Subgrade-Pumping <ul><li>The forceful displacement of soil and water from beneath the pavement through joints and cracks. ...
Geotextiles <ul><li>Highly recommended </li></ul><ul><li>Different types for different applications </li></ul><ul><li>Over...
Separation Layer- Geotextiles <ul><li>Seperation </li></ul><ul><ul><li>Prevents intermixing of drain rock & subgrade </li>...
Geotextiles <ul><li>TenCate Mirifi 140N most recommended </li></ul><ul><ul><li>Non- woven polypropylene </li></ul></ul><ul...
 
Rainwater Harvesting- Finley Stadium Chattanooga, Tennessee
<ul><li>Gradation </li></ul><ul><li>Angularity </li></ul><ul><li>Hardness </li></ul>Selection of Drain Rock (base) is impo...
Base Thickness <ul><li>Typically 6 inches </li></ul><ul><li>Greater than 6 inches to increase storage </li></ul><ul><li>Gr...
Storage Capacity <ul><li>Storage capacity typically governs design </li></ul><ul><li>Depends on porosity of pavement, subb...
Additional Storage
  Pervious Concrete: What & Why?
Pervious Concrete…What is it? <ul><li>Constituents </li></ul><ul><ul><li>Cement </li></ul></ul><ul><ul><li>Water </li></ul...
Mixture Proportions <ul><li>2400-2600 lbs.- #89 stone </li></ul><ul><li>100-400 lbs.- silica sand (<#16- >#200) </li></ul>...
Aggregate <ul><li>Texture and Porosity Affected by </li></ul><ul><ul><li>Aggregate Size </li></ul></ul><ul><ul><li>Aggrega...
 
Surface Texture Comparison 3/8” rock or gravel is most common size due to smoothness and appearance
Cementitious Quantity <ul><li>Maintain the void structure </li></ul><ul><li>Maintain point to point aggregate contact </li...
Water Content <ul><li>Water/ Cement Ratio: 0.27-0.32  </li></ul><ul><li>Contractor Controls Water Content to Match: </li><...
Water and Plasticity <ul><li>Recognize an unstable paste </li></ul><ul><li>Recognize a wet, metallic sheen </li></ul><ul><...
Admixtures <ul><li>Set Controlling </li></ul><ul><ul><li>Retarders </li></ul></ul><ul><ul><li>Hydration Stabilizers </li><...
Proprietary Systems Acrylic/ Latex Polymers <ul><li>Ecocreto, Stoneycrete, Magna-Crete, Enviro-Crete, Percocrete, Filtercr...
An Unnatural Act <ul><li>Making concrete that includes voids.  </li></ul><ul><li>Intentionally reducing concrete density. ...
<ul><li>Void content= 10 – 25% </li></ul><ul><li>Drainage rate = </li></ul><ul><li>  3 to 8 gal/min/ft 2 </li></ul><ul><li...
<ul><li>110 to 130 lbs/ft 3  unit weight </li></ul><ul><ul><li>Corresponds to void content </li></ul></ul><ul><li>1000 to ...
 
Properties Testing- Quality Control <ul><li>Conventional concrete testing methods do NOT apply </li></ul><ul><ul><li>No/ L...
ASTM C09.49 Standards & Work Groups <ul><li>Fresh density and void content-  C1688 </li></ul><ul><li>Field Permeability-  ...
<ul><li>Designation: C 1688/ C 1688M – 08 </li></ul><ul><li>0.25 cubic ft. bowl & standard proctor hammer </li></ul><ul><u...
<ul><li>Designation: C 1701/C 1701M – 09 </li></ul>Standard Test Method for Infiltration Rate of In Place Pervious Concrete
<ul><li>High variability with standard procedures  </li></ul><ul><ul><li>Partially due to inconsistent modification of tes...
Falling Head Permeability Test
Evaluating the Surface Durability Potential of a Pervious Concrete Mixture
Raveling- Field Check
Pressure Washer Testing? <ul><li>3000 psi </li></ul><ul><li>1 gpm </li></ul><ul><li>3-inch separation-nozzle to concrete <...
Unit Weight – At the Plant <ul><li>The unit weight is simply the weight of one cubic foot </li></ul><ul><li>Critical in qu...
Pulling Cores <ul><li>Larger projects might require cores </li></ul><ul><li>Measure thickness </li></ul><ul><ul><li>No < ¼...
Load Test
  Pervious Concrete: How? Design & Construction
How? <ul><li>Relatively new technology (in Texas) </li></ul><ul><li>Few established standards and methods </li></ul><ul><l...
Pervious Concrete Truths <ul><li>•  You have to select, design, and build it right </li></ul><ul><li>•  You can design it ...
Key Tools & Resources  
 
Pervious Concrete-Technical Resources
 
<ul><li>Administered by Texas Aggregates & Concrete Assoc. </li></ul><ul><li>Several classes offered annually across the s...
National Network <ul><li>Portland Cement Association </li></ul><ul><li>National Ready Mixed Concrete Association </li></ul...
Balance
Structural Design Procedures <ul><li>ACI 522 Chapter 6 – AASHTO or PCA if strength falls within limits (usually doesn’t) <...
Further Research Needed–  Design and Performance <ul><li>Field performance studies under heavy traffic </li></ul><ul><li>F...
Further Research – Materials <ul><li>Structural grades </li></ul><ul><li>Different aggregate gradations </li></ul><ul><li>...
In the Interim… <ul><li>Increase Attention to Detail </li></ul><ul><li>Increase Emphasis on Construction Quality </li></ul...
Pavement Thickness <ul><li>Minimums </li></ul><ul><ul><li>4-5” Sidewalks& Trails </li></ul></ul><ul><ul><li>5-6” Residenti...
<ul><li>Traffic: </li></ul><ul><ul><li>Type  </li></ul></ul><ul><ul><li>Quantity </li></ul></ul><ul><li>Subgrade & Subbase...
Strength vs. Thickness <ul><li>Section strength – proportionate to: </li></ul><ul><ul><li>Square of the thickness </li></u...
Thickness vs. Modulus of Rupture
Thickness… <ul><li>Turns out to be the answer to a number of questions </li></ul><ul><li>Poor Subgrade? </li></ul><ul><ul>...
What does this say about strength? <ul><li>If you can’t have strength </li></ul><ul><ul><li>Make it thicker </li></ul></ul...
Finishing: The Typical Process <ul><li>Spreading </li></ul><ul><li>Strike-off </li></ul><ul><li>Compacting </li></ul><ul><...
<ul><li>“ Each builder has a style; a favorite way to assemble his method, his setup, and his crew. Some will perform thei...
Finishing Qualifications <ul><li>Require a Contractor who has successfully completed the NRMCA Pervious Concrete Contracto...
Various Placing Equipment Types
Concrete Compaction More Compaction = Less Porosity Strength Increases   Porosity Decreases   More Compaction  
 
Ensuring a Durable Surface- Preventing Raveling <ul><li>Sufficient Compaction </li></ul><ul><ul><li>Match Placement Method...
Compaction of pervious concrete material during placement
Jointing and Cross Rolling
Edge Thickness & Compaction is Critical
Stresses are Greatest at Edges & Corners
Edging ? <ul><li>Some debate </li></ul><ul><li>May prevent raveling </li></ul><ul><li>May promote raveling </li></ul><ul><...
Evaporation Control <ul><li>Sub base Saturation </li></ul><ul><li>Fogging </li></ul><ul><li>Evaporation Retarders </li></u...
Understand Potential for Evaporation <ul><li>Recognize surface area exposure </li></ul><ul><li>Recognize air humidity </li...
Cement Hydration <ul><li>Recognize low water traits </li></ul><ul><li>Recognize early hydration process </li></ul><ul><li>...
Cement Hydration Launch <ul><li>The first fifteen minutes </li></ul><ul><ul><li>Tricalcium Aluminate </li></ul></ul><ul><l...
Recognize Different Evaporation & Set Characteristics <ul><li>Drum Mixer </li></ul><ul><li>Volumetric Mixer </li></ul>
Insufficient Curing
Raveling
Curing 6 MIL PLASTIC
Prepare the Poly <ul><li>Unpacked, Unfolded, Rolled </li></ul><ul><ul><li>Quick installation </li></ul></ul><ul><ul><li>Fo...
Loose Edges
Gaps
Crash and Burn
<ul><li>Shrinkage </li></ul><ul><li>Restraint (friction from the foundation) </li></ul><ul><li>Temperature changes </li></...
<ul><li>Rebar, even epoxy coated, rusts away over time </li></ul><ul><li>Low-slump, high-void material forms poorly around...
Tie Bars?
 
Load Transfer <ul><li>Edge and corner stresses are greatest </li></ul><ul><li>Use Thickened Edges </li></ul><ul><li>Use cu...
Jointing <ul><li>Best Practices </li></ul><ul><ul><li>Control (contraction) </li></ul></ul><ul><ul><li>Construction </li><...
Control Joints <ul><li>15’ typical-20’ max. </li></ul><ul><li>1:1.5 maximum aspect ratio  </li></ul><ul><li>1/4D </li></ul...
Effects of Joint Spacing  10.0 ft 3.0 ft 3.0 ft 3.0 ft Ultra-thin Slabs Deflect Concrete in Compression Standard Slabs Ben...
Jointing Details
Control Joints <ul><li>Tooled </li></ul><ul><li>Saw-cut </li></ul>
Control Joints- Tooled <ul><li>Pizza Cutter </li></ul><ul><li>Thin blade, small radius </li></ul><ul><li>Don’t use traditi...
 
Control Joints- Saw cut <ul><li>Too early= raveling </li></ul><ul><li>Too late= ineffective </li></ul><ul><li>May hinder h...
Sealing Joints? Joints don’t need to be sealed, but sealant can  reduce or eliminate raveling at joints
Construction joints <ul><li>Use thickened section or thickened edges for load transfer issues </li></ul><ul><li>If additio...
 
Isolation Joints <ul><li>Not expansion joints </li></ul><ul><li>Some debate over use </li></ul><ul><li>Proper installation...
 
 
Panels
“ Natural” Construction/ Isolation Joints?
Transition to Asphalt
Header Curb
Where Pervious Concrete Abuts Conventional Pavement or Structures
Important Points for Design & Construction of Pervious Concrete <ul><li>Get a soils report </li></ul><ul><li>Determine thi...
  Pervious Concrete: Other Considerations
Striping
Integral Color
Stamping
Stained
Pervious Concrete- LEED 3.0 Considerations <ul><li>May Contribute to: </li></ul><ul><ul><li>SS Credit 6.1 Stormwater Desig...
 
 
Pervious Concrete Maintenance <ul><li>Design the installation with minimal exposure to sediment from other areas </li></ul...
Prevent Runoff
Prevent Debris from Washing Onto Slab
Slope Grade Away from Pavement SWALE
Grade Pavement High
No Adjacent Dirt Parking
Islands/Vegetation
Routine Maintenance- Litter Removal <ul><li>Leaf blowers work well if done on a regular basis </li></ul><ul><li>Vacuum tru...
Routine Maintenance- Litter Removal
Vacuum Sweeping
Vacuum Sweeping
 
 
Removing Sediments  <ul><li>Low pressure, high volume water </li></ul><ul><li>High pressure water usually not needed </li>...
Before and After Cleaning
Repair Work
Questions? For additional information or assistance, Please call or email: Sean Van Delist 210-883-8060 [email_address]
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Pervious Concrete: Getting Down to the Details

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The latest iteration of my pervious concrete presentation. Recently presented to English & Associates and Texas ASLA Houston section.

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  • “ Big Three” pollutants in urban runoff Sediment (dirt and debris) Heavy Metals - brake linings Hydrocarbons Hydrocarbon sources Asphalt pavement – Primary source Surface treatments and sealers Middle Tennessee State studies – 90 – 95% of hydrocarbons from binder and sealers Oil that drips onto pavements from vehicles Pervious concrete provides more than 80% reduction of “Big Three”
  • Other uses for pervious concrete include erosion protection and greenhouse floors.
  • Some of the images used in this presentation shows worker that are not using the proper safety equipment or clothing.
  • Outdoor synthetic tracks. Nike Grind
  • A pervious concrete pavement in a stormwater management design is a part of a system, and not just a pavement in itself. The pavement supports traffic loading while allowing water to pass through the concrete surface. For better effectiveness water should flow vertically through the pavement runoff from the pavement should be minimized. The base, the material under the pavement, acts as temporary storage while supporting the pavement. Grade or slope in the design will affect the storage capacity of the system. A flat pervious concrete pavement system offers the maximum storage capacity. However site conditions and other project constraints may not allow for a flat pervious concrete pavement system to be an economically viable option.
  • Here are examples of a residential street and a roadway through a park.
  • As the compaction is increased, the permeability is decreased and a compromise has to be reached. Experience has shown that a compaction of the base/subgrade should be in a range of 92 to 95% of the modified proctor compaction. A uniform compaction of 92% seems to give good results of pavement support and permeability. A value of 95% gives good results for the aggregate base. These values will change depending on the subgrade materials and local codes. The concept is to have sufficient pavement support while maintaining sufficient permeability.
  • No standards have been developed for the design of the thickness of base materials below pervious concrete pavements. The design thickness has been based on prior experience of performance. Most base thicknesses, for parking area designs, have been at least a 6-inch section. Some designs may indicate a section greater than 6 inches if required to meet stormwater volume storage. Base thickness requirements may also include considerations as to whether the pavement will be subject to deep frost line conditions. In some cases a separate base material may not be required. The pervious concrete may be placed directly on a uniformly compacted soil. This may be the case if pervious concrete is used in areas around trees where the tree roots should not be disturbed. This is also possible in areas where the native soils are highly permeable, and with minimal compaction make a good base for the pavement.
  • The total storage capacity of the pervious concrete system includes the capacity of the pervious concrete pavement, the storage capacity of the aggregate subbase, and the amount of water which leaves the system by infiltration into the underlying subgrade. If the pervious concrete has 20% porosity then every inch of pavement can store 0.20 inches of water. If the subbase, number 67 stone for example, has a porosity of 40% then every inch of pavement can store 0.40 inches of rain. Therefore, a 6 inch pervious concrete pavement on 6 inches of #67 stone can store 3.6 inches of water.
  • Texture and Porosity are affected by aggregate size, grading, angularity, and the paving equipment you use.
  • 3/8” rock or gravel is most common size due to smoothness and appearance.
  • The water content must match two things. One is the equipment being used and the other is the weather. The heavier the equipment the lower the water to cement ratio could be. The hotter the weather the higher the water to cement ratio has to be. You can always add water to the concrete at the jobsite to get the correct water to cement ratio.
  • Pervious concrete mixtures are stiff mixtures with low water content, and tend to stiffen up faster than higher slump conventional concrete. Set retarding admixtures are often used. Hydration stabilizing admixtures are also used. Air entraining admixtures are used to increase the resistance to damage from freezing and thawing. Viscosity modifying admixtures are gum-based products that improve the cohesivity (stickiness and bonding potential) of cement paste. Their use in pervious concrete mixtures has been seen to provide benefits to the consistency of the mixture during installation. Integral color can be added to pervious concrete in liquid or powdered form. The type, and color, of the aggregate may also influence the decision of using color. Broadcast, dry-shake color, applied to the surface of concrete flatwork is not recommended.
  • A typical pervious concrete mix will have anywhere from 15 to 30 percent voids, depending largely on the size of the aggregate used. Field studies have shown that a pervious concrete made with 3/8” aggregate exhibits an average void content of 20 to 25 percent. Because there is no fine aggregate, the density (unit weight) of pervious concrete is slightly less than conventional concrete, weighing in at about 100 to 120 pcf. Compressive strength of pervious concrete averages from 2,500 to 3,500 psi under typical conditions. For applications where higher strengths are deemed necessary, a small amount of fine aggregate (about 500 lbs per CY) can increase the compressive strength. Realize, however, that this will decrease the percentage of voids in the mix. In most cases, we recommend that compressive strength should not be used as acceptance criteria. Rather, you should use density and void content. For acceptance criteria, the density (unit weight) of the plastic pervious concrete should be within 5 lbs (+/-) of the approved mix design.
  • A typical pervious concrete mix will have anywhere from 15 to 30 percent voids, depending largely on the size of the aggregate used. Field studies have shown that a pervious concrete made with 3/8” aggregate exhibits an average void content of 20 to 25 percent. Because there is no fine aggregate, the density (unit weight) of pervious concrete is slightly less than conventional concrete, weighing in at about 100 to 120 pcf. Compressive strength of pervious concrete averages from 2,500 to 3,500 psi under typical conditions. For applications where higher strengths are deemed necessary, a small amount of fine aggregate (about 500 lbs per CY) can increase the compressive strength. Realize, however, that this will decrease the percentage of voids in the mix. In most cases, we recommend that compressive strength should not be used as acceptance criteria. Rather, you should use density and void content. For acceptance criteria, the density (unit weight) of the plastic pervious concrete should be within 5 lbs (+/-) of the approved mix design.
  • The concrete producer should perform a density (unit weight) test on the first few loads of concrete each production day to verify the plant is running properly. The unit weight is simply the weight of one cubic foot. It is critical in quality control. The Unit Weight should be +/- 5 pcf of specified.
  • For larger projects, the engineer might require core test to check for stab thickness and dry density. If necessary, core samples can be obtained from the pavement in accordance ASTM C 42, Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete, to measure the in-place density and other properties as needed. The density of cores after trimming can be determined by determining the calculated volume of the core from its dimensions or by procedures described in ASTM C 140, Test Methods for Sampling and Testing Concrete Masonry Units and Related Units . ASTM is in the process of standardizing test procedures for pervious concrete.
  • History: Nearly 750,000 sq. ft. in Texas (all &lt; 10 years old) Almost 500,000 sq. ft. in Austin area alone No known structural failures Some edge failures Mostly all “failures” due to improper installation Surface sealing Raveling Local History: Nearly 750,000 sq. ft. in Texas (all &lt; 10 years old) Almost 500,000 sq. ft. in Austin area alone No known structural failures Some edge failures Mostly all “failures” due to improper installation Surface sealing Raveling
  • For parking lot designs, a 6-inch section has been shown to be successful under automobile traffic, with occasional truck traffic. An 8-inch section is normally used for residential streets and heavier truck traffic areas such as delivery lanes.
  • The typical process of finishing pervious concrete has five basic steps. Spreading the concrete means raking it off of the truck. Striking off the pavement a little high. Then compact the concrete down to the right elevation. Jointing and edging occurs next followed immediately by curing.
  • The more compaction you have the stronger the concrete the less porosity. With pervious poured out of the truck with not compaction you can get severe raveling of the surface, that is the surface will deteriorate. It has very little strength but a great amount of porosity. The perfect amount of compaction will optimize strength and porosity. If you over compact you can seal the surface. You have great strength but no porosity which mean no drainage and the system will fail.
  • Critical issues of construction that can lead to failure if not done properly are subgrade compaction, proper mixing water, sufficient compaction, and preventing evaporation.
  • Use 6 mil plastic for curing. A few points when securing with plastic sheeting: do not use dirt; use 2x4s or reinforcing bars. Keep in place for at least 7 days; and make sure it is cut and ready before discharge begins and maybe even before the trucks arrive.
  • When joints are placed in pervious concrete pavements, it should be jointed when the pavement dimensions are greater than 20 feet in any direction. In some places a 15-foot joint spacing is standard practice. Drying shrinkage in pervious concrete is not as severe as in conventional concrete, and therefore will have a reduced chance of cracking. Experience should dictate the typical joint spacing in a local region. Joints can be placed closer together if the layout warrants. The panels between the joints should be made as square as possible, and the length to width ratio should not exceed 1.5.
  • Here’s an example of the joint perpendicular to the curb.
  • You can joint the concrete in two ways. You can tool the joint or cut the joint. Tooled joints are preferred. The use of pavement saws for cutting joints are discouraged because the dust residue from the sawing operation can settle into the pores of the pavement. If care is taken to vacuum the dust during the sawing operation then this method of cutting joints is acceptable. Alternatively, water may be used in the sawing operation to flush the pores of the pavement immediately after sawing.
  • There is no need to seal joints.
  • Consider isolation joint between pervious and conventional pavement.
  • Here’s an example of a pervious concrete driveway.
  • When placing a pervious concrete pavement adjacent to an asphalt pavement, for example, curbing could be used to prevent water from seeping into the base of the asphalt pavement. This is called a header curb.
  • Here are other examples of Header Curbs.
  • 15 mil Stego wrap, wrapped underneath the drain rock 12 -24” in
  • Pervious concrete can be striped.
  • Here’s an example of how pervious pavement should not be treated.
  • Curbs can also be used to prevent unpaved areas from draining onto the pavement by controlling the flow path of storm water during a storm event. These areas, allowed to drain onto the pervious concrete, could bring soil or debris that could impact the performance of the pavement/stormwater system.
  • Slope surrounding grade away from pervious pavement to avoid debris from clogging the slab.
  • Make sure the pavement is graded higher than the surrounding landscaping.
  • Avoid having dirt parking next to a pervious pavement.
  • Vegetated swales, as defined in Low Impact Development (LID), can be used as separators between parking areas. These areas are designed to be below the top of pavement, and become a part of the overall stormwater management design. Trees, or shrubs, may also be planted in the vegetated swales.
  • No standards have been developed for the design of the thickness of base materials below pervious concrete pavements. The design thickness has been based on prior experience of performance. Most base thicknesses, for parking area designs, have been at least a 6-inch section. Some designs may indicate a section greater than 6 inches if required to meet stormwater volume storage. Base thickness requirements may also include considerations as to whether the pavement will be subject to deep frost line conditions. In some cases a separate base material may not be required. The pervious concrete may be placed directly on a uniformly compacted soil. This may be the case if pervious concrete is used in areas around trees where the tree roots should not be disturbed. This is also possible in areas where the native soils are highly permeable, and with minimal compaction make a good base for the pavement.
  • No standards have been developed for the design of the thickness of base materials below pervious concrete pavements. The design thickness has been based on prior experience of performance. Most base thicknesses, for parking area designs, have been at least a 6-inch section. Some designs may indicate a section greater than 6 inches if required to meet stormwater volume storage. Base thickness requirements may also include considerations as to whether the pavement will be subject to deep frost line conditions. In some cases a separate base material may not be required. The pervious concrete may be placed directly on a uniformly compacted soil. This may be the case if pervious concrete is used in areas around trees where the tree roots should not be disturbed. This is also possible in areas where the native soils are highly permeable, and with minimal compaction make a good base for the pavement.
  • Removing debris from the surface of the pavement is important in maintaining the porosity of the pervious concrete pavements. Trash, such as leaves or paper, may degrade into small particles that may migrate into the void structure of the pavement and reduce the porosity. Periodic sweeping, or a combination of a vacuuming and sweeping, can help reduce the infiltration of materials into the pavement. Here’s an example of pervious before cleaning and after cleaning.
  • You will see color variation if you try to repair a slab. In this case the island was moved and new pervious was placed. Naturally it didn’t match the existing slab.
  • Pervious Concrete: Getting Down to the Details

    1. 1. Pervious Concrete Getting Down to the Details Sean Van Delist Cement Council of Texas
    2. 2. <ul><li>Permeable Pavements </li></ul><ul><li>Pervious Concrete: What & Why? </li></ul><ul><li>Pervious Concrete: How? Design & Construction </li></ul><ul><li>Pervious Concrete: Other Considerations </li></ul><ul><li>Questions & Answers </li></ul>Outline
    3. 3. Permeable Pavements: Applying the Technology
    4. 4. Porous Pavements Bruce K. Ferguson
    5. 6. <ul><li>Permeable Pavements are pavements that allow the passage of stormwater through the surface course layer. Permeable Pavements can provide the following benefits: </li></ul><ul><li>  </li></ul><ul><ul><li>Reduce Stormwater Runoff (Quantity) </li></ul></ul><ul><ul><li>Clean Stormwater (Quality) </li></ul></ul><ul><ul><li>Cool Stormwater </li></ul></ul><ul><ul><li>Replenish the water table/ aquifers </li></ul></ul><ul><ul><li>Allow for Rain water Harvesting </li></ul></ul><ul><ul><li>Reduce Urban Sprawl </li></ul></ul><ul><ul><li>Protect Trees </li></ul></ul><ul><ul><li>Reduce Urban Heat Island Effect </li></ul></ul><ul><ul><li>Eliminates Ponding Water </li></ul></ul>What Are Permeable Pavements?
    6. 7. The Problem to be Fixed <ul><li>Pervious Surfaces Absorbs </li></ul><ul><li>Stores Water </li></ul><ul><li>Reduces or eliminates run-off </li></ul><ul><li>Removes and destroys pollutants </li></ul><ul><li>Infiltrates into natural soil </li></ul><ul><ul><li>Recharges ground water </li></ul></ul><ul><ul><li>Sustains local ecosystem </li></ul></ul><ul><ul><li>Maintains stream base flow </li></ul></ul>Rainfall <ul><li>Impervious Surfaces Deflects </li></ul><ul><li>Flushes pollutants into streams </li></ul><ul><li>Aggravates flooding </li></ul><ul><li>Erodes channels </li></ul><ul><li>Ground water declines </li></ul><ul><li>Streams go dry in summer </li></ul><ul><li>Aquatic ecosystems die </li></ul><ul><li>Water supplies insecure </li></ul>Rainfall and Run-off
    7. 8. Pervious Concrete- 5 basic permitted uses: <ul><ul><li>Stormwater runoff reduction (quantity) </li></ul></ul><ul><ul><li>Stormwater treatment (quality) </li></ul></ul><ul><ul><li>Tree protection </li></ul></ul><ul><ul><li>Wetlands protection </li></ul></ul><ul><ul><li>Zoning credits </li></ul></ul>
    8. 9. Stormwater Quantity
    9. 10. <ul><li>Filtration of TSS </li></ul><ul><li>Oxidation </li></ul><ul><li>Soil Filtration & Capture </li></ul><ul><li>Bioremediation </li></ul>Stormwater Quality
    10. 11. Tree Protection
    11. 12. Wetlands Protection
    12. 13. <ul><li>Austin </li></ul><ul><ul><li>0% credit for vehicular applications </li></ul></ul><ul><ul><li>100% credit for pedestrian applications </li></ul></ul><ul><li>LCRA Highland Lakes </li></ul><ul><ul><li>90% credit for all applications </li></ul></ul><ul><li>San Antonio </li></ul><ul><ul><li>Required for exceeding maximum parking limits </li></ul></ul><ul><li>TCEQ- Edward’s Aquifer </li></ul><ul><ul><li>Not currently allowed over recharge w/o special consideration </li></ul></ul>ZoningCredits
    13. 14. Other Uses
    14. 15. Other Uses
    15. 17. Other Uses
    16. 18. Pervious Pavement- It’s a System. <ul><li>Properly designed and constructed Permeable Pavement Systems provide a Structural and Hydraulic solution for sitework pavement loading conditions, stormwater detention and quality improvement requirements. </li></ul>
    17. 19. <ul><li>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: </li></ul><ul><li>  </li></ul><ul><li>Full Exfiltration </li></ul><ul><li>No Exfiltration </li></ul><ul><li>Partial Exfiltration </li></ul>Permeable Pavements
    18. 20. Full Exfiltration Permeable Surface Course Gravel/Stone 40% voids Filter Fabric Curb
    19. 21. No Exfiltration Permeable Surface Course Gravel/Stone 40% voids Liner Curb
    20. 22. Partial Exfiltration Permeable Surface Course Gravel/Stone 40% voids Filter Fabric Curb
    21. 23. Objectives <ul><li>Three positions influence the decisions. </li></ul>Producer & Installer Hydrology Structure
    22. 24. Surface Course Types: Choosing the Proper Material for the Specific Application
    23. 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,
    24. 26. Considerations <ul><li>All systems function hydrologically </li></ul><ul><li>All systems require some type of maintenance </li></ul><ul><li>Match surface course for site conditions: </li></ul><ul><ul><li>Climate </li></ul></ul><ul><ul><li>Type of Traffic </li></ul></ul><ul><ul><li>Quantity of Traffic </li></ul></ul>
    25. 27. Decks
    26. 28. Mulch
    27. 29. <ul><li>Commonly called Decomposed Granite (DG) </li></ul>Crushed Granite
    28. 30. <ul><li>Filled with gravel, crushed stone or soil for grass to grow thru </li></ul>Plastic paving cells
    29. 31. <ul><li>Also known as </li></ul><ul><li>Permeable Friction Course (PFC) </li></ul>Permeable Asphalt
    30. 32. <ul><li>Epoxy, polyurethanes, or other polymers used to bind aggregate or rubber chips together </li></ul>Polymer cement concretes
    31. 34. Pervious Concrete
    32. 35.   PICP
    33. 36. Grid/ Turf Pavers & Grasscrete
    34. 37. Main Differences to Consider <ul><li>Subgrade </li></ul><ul><ul><li>Must accommodate water flow </li></ul></ul><ul><ul><li>Design for intentionally weakened subgrade </li></ul></ul><ul><li>Separation Layer </li></ul><ul><ul><li>Use with all soils except sand </li></ul></ul><ul><li>Subbase </li></ul><ul><ul><li>gap-graded </li></ul></ul><ul><ul><li>Storage layer </li></ul></ul>Subbase Subgrade
    35. 38. Layout/Grade/Slope <ul><li>Part of System </li></ul><ul><ul><li>Supports traffic </li></ul></ul><ul><ul><li>Allows water to pass </li></ul></ul><ul><li>Water should flow vertically </li></ul><ul><li>Minimize horizontal flow </li></ul><ul><li>Storage in gravel base </li></ul><ul><li>Can use pavement and ponding zone </li></ul><ul><li>Flat system offers the maximum storage </li></ul>
    36. 42. Hydrology- Considerations <ul><li>Rainfall Characteristics </li></ul><ul><li>Soil Permeability </li></ul><ul><li>Stormwater Management Objectives </li></ul>
    37. 43. Soil Permeability <ul><li>ASTM D3385 -09 Standard Test Method for Infiltration Rate of Soils in Field Using Double-Ring Infiltrometer </li></ul><ul><li>ASTM D5093 -02(2008) Standard Test Method for Field Measurement of Infiltration Rate Using Double-Ring Infiltrometer with Sealed-Inner Ring </li></ul>
    38. 44. Subgrade Soils
    39. 45. Subgrade Compaction <ul><li>Of some debate </li></ul><ul><li>Compact to 92 - 95% of modified proctor </li></ul><ul><li>Compaction of the subgrade is inversely proportional to its permeability. </li></ul><ul><li>Uniformity is more important than compaction percentage </li></ul>
    40. 46. Subgrade-Pumping <ul><li>The forceful displacement of soil and water from beneath the pavement through joints and cracks. </li></ul><ul><li>Conditions for pumping: </li></ul><ul><li>1. Subgrade soils that will go into suspension </li></ul><ul><li>2. Free water between slab and subgrade </li></ul><ul><li>3. Frequent heavy wheel loads </li></ul>insert photo from winpump.ppt
    41. 47. Geotextiles <ul><li>Highly recommended </li></ul><ul><li>Different types for different applications </li></ul><ul><li>Overlap based on soil strength </li></ul><ul><li>May add strength to subgrade- compensates for reduced compaction </li></ul>
    42. 48. Separation Layer- Geotextiles <ul><li>Seperation </li></ul><ul><ul><li>Prevents intermixing of drain rock & subgrade </li></ul></ul><ul><li>Confinement </li></ul><ul><ul><li>Helps interlock drainrock </li></ul></ul><ul><li>Reinforcement </li></ul><ul><ul><li>Carrys some tensile load </li></ul></ul><ul><li>Protection </li></ul><ul><ul><li>Protects permeab ility of subgrade </li></ul></ul><ul><li>Filtration </li></ul><ul><ul><li>Allows passage of water </li></ul></ul>
    43. 49. Geotextiles <ul><li>TenCate Mirifi 140N most recommended </li></ul><ul><ul><li>Non- woven polypropylene </li></ul></ul><ul><ul><li>“ filter” fabric </li></ul></ul><ul><ul><li>6 heavier grades </li></ul></ul><ul><li>500X may be more useful in clay soils </li></ul><ul><ul><li>Woven polypropylene </li></ul></ul><ul><ul><li>“ stabilizer” fabric </li></ul></ul><ul><ul><li>100X & 600X also available </li></ul></ul>
    44. 51. Rainwater Harvesting- Finley Stadium Chattanooga, Tennessee
    45. 52. <ul><li>Gradation </li></ul><ul><li>Angularity </li></ul><ul><li>Hardness </li></ul>Selection of Drain Rock (base) is important
    46. 53. Base Thickness <ul><li>Typically 6 inches </li></ul><ul><li>Greater than 6 inches to increase storage </li></ul><ul><li>Greater than 6 inches for freeze-thaw </li></ul><ul><li>Not required in some cases </li></ul><ul><ul><li>Minimize root damage </li></ul></ul><ul><ul><li>Native soils highly permeable </li></ul></ul>
    47. 54. Storage Capacity <ul><li>Storage capacity typically governs design </li></ul><ul><li>Depends on porosity of pavement, subbase, & subgrade. </li></ul><ul><li>1” of pavement with 20% porosity can store 0.20” </li></ul><ul><li>1” of #57 stone base with 40% porosity can store 0.40” </li></ul><ul><li>6” pavement on 6” subbase can store 3.6” of rain </li></ul><ul><li>Curbs can be used for additional storage (ponding) </li></ul>(20%) 6 in. + (40%) 6 in. = 3.6 in. (20%) 6 in. + (40%) 6 in. + (100%) 6 in. = 9.6 in.
    48. 55. Additional Storage
    49. 56. Pervious Concrete: What & Why?
    50. 57. Pervious Concrete…What is it? <ul><li>Constituents </li></ul><ul><ul><li>Cement </li></ul></ul><ul><ul><li>Water </li></ul></ul><ul><ul><li>Coarse Aggregates </li></ul></ul><ul><ul><li>Admixtures </li></ul></ul><ul><li>Point-to-Point Aggregate Contact </li></ul><ul><li>Adhered with Past Bridge </li></ul><ul><li>Random Structure </li></ul>
    51. 58. Mixture Proportions <ul><li>2400-2600 lbs.- #89 stone </li></ul><ul><li>100-400 lbs.- silica sand (<#16- >#200) </li></ul><ul><li>400-650 lbs.- portland cement </li></ul><ul><li>0.27-0.32 w/c ratio </li></ul><ul><li>admixtures </li></ul>
    52. 59. Aggregate <ul><li>Texture and Porosity Affected by </li></ul><ul><ul><li>Aggregate Size </li></ul></ul><ul><ul><li>Aggregate Grading </li></ul></ul><ul><ul><li>Aggregate Angularity </li></ul></ul><ul><ul><li>Paving Equipment </li></ul></ul><ul><li>Volume of aggregate per cubic yard of concrete is about 27 cubic feet </li></ul>
    53. 61. Surface Texture Comparison 3/8” rock or gravel is most common size due to smoothness and appearance
    54. 62. Cementitious Quantity <ul><li>Maintain the void structure </li></ul><ul><li>Maintain point to point aggregate contact </li></ul><ul><li>Maintain the paste thickness </li></ul>Adjust the cementitious content to coat the aggregate with .015 inch thickness.
    55. 63. Water Content <ul><li>Water/ Cement Ratio: 0.27-0.32 </li></ul><ul><li>Contractor Controls Water Content to Match: </li></ul><ul><ul><li>Equipment </li></ul></ul><ul><ul><li>Weather </li></ul></ul><ul><li>Water may be added at the jobsite </li></ul>
    56. 64. Water and Plasticity <ul><li>Recognize an unstable paste </li></ul><ul><li>Recognize a wet, metallic sheen </li></ul><ul><li>Recognize a flat, dull appearance </li></ul>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.
    57. 65. Admixtures <ul><li>Set Controlling </li></ul><ul><ul><li>Retarders </li></ul></ul><ul><ul><li>Hydration Stabilizers </li></ul></ul><ul><li>Viscosity Modifying Admixtures (VMA) </li></ul><ul><li>Integral Color </li></ul><ul><li>Proprietary Additives- Acrylic/ Latex Polymers </li></ul>
    58. 66. Proprietary Systems Acrylic/ Latex Polymers <ul><li>Ecocreto, Stoneycrete, Magna-Crete, Enviro-Crete, Percocrete, Filtercrete, Leakcrete… </li></ul><ul><li>Almost any liquid latex or acrylic will work </li></ul><ul><li>Increases strength, color steadfastness and COST! </li></ul>
    59. 67. An Unnatural Act <ul><li>Making concrete that includes voids. </li></ul><ul><li>Intentionally reducing concrete density. </li></ul><ul><li>Knowingly reducing concrete strength. </li></ul>
    60. 68. <ul><li>Void content= 10 – 25% </li></ul><ul><li>Drainage rate = </li></ul><ul><li> 3 to 8 gal/min/ft 2 </li></ul><ul><li>Equivalent of 275” to 725” of rain per hour! </li></ul>Pervious Concrete Properties
    61. 69. <ul><li>110 to 130 lbs/ft 3 unit weight </li></ul><ul><ul><li>Corresponds to void content </li></ul></ul><ul><li>1000 to 4000 psi strength </li></ul><ul><ul><li>Introduction of small amount of fine aggregate and/ or polymers help can increase strength. </li></ul></ul>Pervious Concrete Properties
    62. 71. Properties Testing- Quality Control <ul><li>Conventional concrete testing methods do NOT apply </li></ul><ul><ul><li>No/ Low slump concrete </li></ul></ul><ul><ul><li>Compressive/ Flexural strength testing of lab & field samples has high variability and less accuracy </li></ul></ul><ul><li>Density & Void Content and Field Permeability are only tests for acceptance </li></ul><ul><li>other ASTM Standards & Testing Methods are currently under development </li></ul>
    63. 72. ASTM C09.49 Standards & Work Groups <ul><li>Fresh density and void content- C1688 </li></ul><ul><li>Field Permeability- C1701 </li></ul><ul><li>Compressive Strength/ Flexural Strength </li></ul><ul><li>Hardened Density and Voids </li></ul><ul><li>Surface Durability </li></ul>
    64. 73. <ul><li>Designation: C 1688/ C 1688M – 08 </li></ul><ul><li>0.25 cubic ft. bowl & standard proctor hammer </li></ul><ul><ul><li>20 blows per 2 layers </li></ul></ul><ul><li>D ensity= M ass/ V olume </li></ul><ul><li>Void content ( U )= T heoretical- D ensity T heoretical </li></ul>Standard Test Method for Density and Void Content of Freshly Mixed Pervious Concrete
    65. 74. <ul><li>Designation: C 1701/C 1701M – 09 </li></ul>Standard Test Method for Infiltration Rate of In Place Pervious Concrete
    66. 75. <ul><li>High variability with standard procedures </li></ul><ul><ul><li>Partially due to inconsistent modification of test </li></ul></ul><ul><ul><li>Partially due to nature of materials </li></ul></ul><ul><li>Will always be difficult to match placement conditions </li></ul><ul><li>Current Proposal </li></ul><ul><ul><li>4X8 cylinders- 2 layers- 5 drops of proctor hammer </li></ul></ul>Strength Testing
    67. 76. Falling Head Permeability Test
    68. 77. Evaluating the Surface Durability Potential of a Pervious Concrete Mixture
    69. 78. Raveling- Field Check
    70. 79. Pressure Washer Testing? <ul><li>3000 psi </li></ul><ul><li>1 gpm </li></ul><ul><li>3-inch separation-nozzle to concrete </li></ul>
    71. 80. Unit Weight – At the Plant <ul><li>The unit weight is simply the weight of one cubic foot </li></ul><ul><li>Critical in quality control </li></ul><ul><li>Unit Weight should be +/- 5 pcf of design </li></ul><ul><li>Should be performed at the plant </li></ul>ASTM C 138
    72. 81. Pulling Cores <ul><li>Larger projects might require cores </li></ul><ul><li>Measure thickness </li></ul><ul><ul><li>No < ¼” </li></ul></ul><ul><ul><li>No > ½” </li></ul></ul><ul><li>Measure Dry Density </li></ul><ul><ul><li>+ or - 5 pcf </li></ul></ul>ASTM C 42
    73. 82. Load Test
    74. 83. Pervious Concrete: How? Design & Construction
    75. 84. How? <ul><li>Relatively new technology (in Texas) </li></ul><ul><li>Few established standards and methods </li></ul><ul><li>Little collected data on properties </li></ul><ul><li>Design and construct conservatively! </li></ul>
    76. 85. Pervious Concrete Truths <ul><li>• You have to select, design, and build it right </li></ul><ul><li>• You can design it to fail </li></ul><ul><li>• You can design it to succeed </li></ul><ul><li>• It requires your knowledge & care </li></ul><ul><li>Pervious concrete is distinct and different </li></ul><ul><li>• Every installation is site-specific </li></ul>
    77. 86. Key Tools & Resources  
    78. 88. Pervious Concrete-Technical Resources
    79. 90. <ul><li>Administered by Texas Aggregates & Concrete Assoc. </li></ul><ul><li>Several classes offered annually across the state </li></ul><ul><li>Private training classes available upon request </li></ul><ul><li>  </li></ul>
    80. 91. National Network <ul><li>Portland Cement Association </li></ul><ul><li>National Ready Mixed Concrete Association </li></ul><ul><li>American Society of Concrete Contractors </li></ul><ul><li>American Concrete Institute </li></ul><ul><li>American Society for Testing and Materials </li></ul>
    81. 92. Balance
    82. 93. Structural Design Procedures <ul><li>ACI 522 Chapter 6 – AASHTO or PCA if strength falls within limits (usually doesn’t) </li></ul><ul><li>PCA Pervious Concrete Pavements suggests AASHTO, WinPas, PCAPAV, ACI 325, or ACI 330R, or using flexible </li></ul><ul><li>pavement structural numbers </li></ul><ul><li>ACI 325.12R and 330.1R tables require minimum flexural strength of 500 psi </li></ul><ul><li>Bruce K. Ferguson “Porous Pavements” – p. 420, “Six inches probably minimum thickness…” and “Heavier traffic loads require thicker slabs.” </li></ul><ul><li>We need a proper engineering procedure </li></ul>
    83. 94. Further Research Needed– Design and Performance <ul><li>Field performance studies under heavy traffic </li></ul><ul><li>Fatigue relationship for pervious concrete </li></ul><ul><li>Performance of aggregate interlock joints over </li></ul><ul><li>time (faulting progression) </li></ul><ul><li>Feasibility of using dowels – diameter, bearing </li></ul><ul><li>stress </li></ul>
    84. 95. Further Research – Materials <ul><li>Structural grades </li></ul><ul><li>Different aggregate gradations </li></ul><ul><li>Small amount of fine aggregate </li></ul><ul><li>Tradeoff between strength and permeability </li></ul>
    85. 96. In the Interim… <ul><li>Increase Attention to Detail </li></ul><ul><li>Increase Emphasis on Construction Quality </li></ul><ul><li>Reduce Emphasis on Strength </li></ul><ul><li>Design Conservatively </li></ul>
    86. 97. Pavement Thickness <ul><li>Minimums </li></ul><ul><ul><li>4-5” Sidewalks& Trails </li></ul></ul><ul><ul><li>5-6” Residential Driveways </li></ul></ul><ul><ul><li>5-7” Parking lots </li></ul></ul><ul><ul><li>7-9” Commercial Driveways </li></ul></ul><ul><li>Consider Conventional Concrete & PICP </li></ul><ul><ul><li>Heavy truck traffic </li></ul></ul><ul><ul><li>High volume traffic </li></ul></ul><ul><ul><li>Areas with a lot of turning </li></ul></ul>pervious conventional
    87. 98. <ul><li>Traffic: </li></ul><ul><ul><li>Type </li></ul></ul><ul><ul><li>Quantity </li></ul></ul><ul><li>Subgrade & Subbase Properties </li></ul><ul><li>Surface Course Properties </li></ul><ul><ul><li>Thickness </li></ul></ul><ul><ul><li>Strength </li></ul></ul>General Pavement Section Thickness Determination
    88. 99. Strength vs. Thickness <ul><li>Section strength – proportionate to: </li></ul><ul><ul><li>Square of the thickness </li></ul></ul><ul><ul><li>Material Strength </li></ul></ul><ul><li>So, if you want a stronger pavement, you can </li></ul><ul><ul><li>Use a LOT stronger concrete </li></ul></ul><ul><ul><li>Use a little more concrete </li></ul></ul><ul><li>If the concrete has to be weaker (and in this case, it does) </li></ul><ul><ul><li>You can make the section as strong by making it thicker </li></ul></ul><ul><ul><ul><li>A Little thicker… </li></ul></ul></ul>
    89. 100. Thickness vs. Modulus of Rupture
    90. 101. Thickness… <ul><li>Turns out to be the answer to a number of questions </li></ul><ul><li>Poor Subgrade? </li></ul><ul><ul><li>Increases Thickness </li></ul></ul><ul><li>More traffic? </li></ul><ul><ul><li>Increase Thickness </li></ul></ul><ul><li>Heavier Loads? </li></ul><ul><ul><li>Increase Thickness </li></ul></ul><ul><li>Lower Flexural Strength? </li></ul><ul><ul><li>Increases Thickness </li></ul></ul>
    91. 102. What does this say about strength? <ul><li>If you can’t have strength </li></ul><ul><ul><li>Make it thicker </li></ul></ul><ul><ul><ul><li>A little thicker </li></ul></ul></ul><ul><li>If you can’t affirm strength </li></ul><ul><ul><li>Make it thicker </li></ul></ul><ul><ul><ul><li>A little thicker </li></ul></ul></ul><ul><li>If you need strength </li></ul><ul><ul><li>Make it thicker </li></ul></ul><ul><ul><li>Don’t make the materials stronger </li></ul></ul><ul><ul><ul><li>Unless you don’t need pervious. </li></ul></ul></ul>
    92. 103. Finishing: The Typical Process <ul><li>Spreading </li></ul><ul><li>Strike-off </li></ul><ul><li>Compacting </li></ul><ul><li>Jointing </li></ul><ul><li>Curing </li></ul>1 2 3 4 5
    93. 104. <ul><li>“ 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…” </li></ul><ul><ul><li>Ken Bunyan (Dave Mitchell) inventor of the Bunyan hydraulic roller screed. </li></ul></ul>
    94. 105. Finishing Qualifications <ul><li>Require a Contractor who has successfully completed the NRMCA Pervious Concrete Contractor Certification Course is required. </li></ul><ul><ul><ul><li>Specified # of Technicians, Installers, & Craftsmen </li></ul></ul></ul><ul><li>In addition to this requirement, the placing contractor shall furnish: </li></ul><ul><ul><ul><li>A minimum of 2 completed projects with addresses </li></ul></ul></ul><ul><ul><ul><li>Unit weight acceptance data </li></ul></ul></ul><ul><ul><ul><li>In-situ pavement test results including void </li></ul></ul></ul><ul><ul><ul><li>content and unit weight </li></ul></ul></ul><ul><ul><ul><li>Sample of product </li></ul></ul></ul><ul><ul><ul><li>Proposed equipment to be used </li></ul></ul></ul>
    95. 106. Various Placing Equipment Types
    96. 107. Concrete Compaction More Compaction = Less Porosity Strength Increases  Porosity Decreases  More Compaction 
    97. 109. Ensuring a Durable Surface- Preventing Raveling <ul><li>Sufficient Compaction </li></ul><ul><ul><li>Match Placement Method with Mix Design </li></ul></ul><ul><li>Proper Mixing Water (w/c) </li></ul><ul><li>Preventing Evaporation </li></ul><ul><ul><li>Rapid Placement </li></ul></ul><ul><ul><li>Proper Curing </li></ul></ul><ul><li>Limit Traffic and Turning </li></ul><ul><ul><li>tire sheer can loosen the aggregate </li></ul></ul><ul><ul><li>One potential solution is to grind down the pavement surface about half an inch. </li></ul></ul>
    98. 110. Compaction of pervious concrete material during placement
    99. 111. Jointing and Cross Rolling
    100. 112. Edge Thickness & Compaction is Critical
    101. 113. Stresses are Greatest at Edges & Corners
    102. 114. Edging ? <ul><li>Some debate </li></ul><ul><li>May prevent raveling </li></ul><ul><li>May promote raveling </li></ul><ul><li>Must be done quickly </li></ul><ul><li>Must be done correctly </li></ul>
    103. 115. Evaporation Control <ul><li>Sub base Saturation </li></ul><ul><li>Fogging </li></ul><ul><li>Evaporation Retarders </li></ul><ul><ul><li>Confilm </li></ul></ul><ul><ul><li>The Bean </li></ul></ul><ul><li>Curing- Plastic Sheeting </li></ul>
    104. 116. Understand Potential for Evaporation <ul><li>Recognize surface area exposure </li></ul><ul><li>Recognize air humidity </li></ul><ul><li>Recognize windy conditions </li></ul>
    105. 117. Cement Hydration <ul><li>Recognize low water traits </li></ul><ul><li>Recognize early hydration process </li></ul><ul><li>Recognize evaporation </li></ul><ul><li>Water / Cement ratio is about ½ the water of conventional concrete. </li></ul><ul><li>The low water cement ratio causes hydration to flash. </li></ul><ul><li>Normal pervious materials require more mixing. </li></ul><ul><li>Batch water and add water must be more closely controlled. </li></ul><ul><li>Mixer discharge is slower and may batter the inside of the drum. </li></ul>
    106. 118. Cement Hydration Launch <ul><li>The first fifteen minutes </li></ul><ul><ul><li>Tricalcium Aluminate </li></ul></ul><ul><li>The first two hours </li></ul><ul><ul><li>Tricalcium Silicate </li></ul></ul>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.
    107. 119. Recognize Different Evaporation & Set Characteristics <ul><li>Drum Mixer </li></ul><ul><li>Volumetric Mixer </li></ul>
    108. 120. Insufficient Curing
    109. 121. Raveling
    110. 122. Curing 6 MIL PLASTIC
    111. 123. Prepare the Poly <ul><li>Unpacked, Unfolded, Rolled </li></ul><ul><ul><li>Quick installation </li></ul></ul><ul><ul><li>Follow closely behind the placement </li></ul></ul><ul><ul><li>Full supply, roll on PVC pipe </li></ul></ul><ul><ul><li>Full length = slab + 3 feet </li></ul></ul><ul><ul><li>Full width = slab + 3 feet </li></ul></ul>
    112. 124. Loose Edges
    113. 125. Gaps
    114. 126. Crash and Burn
    115. 127. <ul><li>Shrinkage </li></ul><ul><li>Restraint (friction from the foundation) </li></ul><ul><li>Temperature changes </li></ul><ul><ul><li>Ambient (expansion/contraction) </li></ul></ul><ul><ul><li>Gradient (may cause curling) </li></ul></ul><ul><li>Changes in moisture content </li></ul><ul><li>Surface drying (may cause curling) </li></ul><ul><li>Service loads </li></ul>Factors That Influence Slab Cracking (Pavement Stresses)
    116. 128. <ul><li>Rebar, even epoxy coated, rusts away over time </li></ul><ul><li>Low-slump, high-void material forms poorly around fiberglass rebar </li></ul><ul><li>Don’t need reinforcement even with conventional concrete for most pavement applications anyway – prepare the subgrade properly and joint it properly to take care of </li></ul><ul><li>crack and curl control </li></ul><ul><li>Remember that an extra inch of concrete can do much more for you than rebar anyway </li></ul>Reinforcement? Dowels?
    117. 129. Tie Bars?
    118. 131. Load Transfer <ul><li>Edge and corner stresses are greatest </li></ul><ul><li>Use Thickened Edges </li></ul><ul><li>Use curbs to control stresses </li></ul>
    119. 132. Jointing <ul><li>Best Practices </li></ul><ul><ul><li>Control (contraction) </li></ul></ul><ul><ul><li>Construction </li></ul></ul><ul><ul><li>Isolation </li></ul></ul><ul><li>Understand limitations of material & construction methods </li></ul><ul><li>Use Common Sense </li></ul>
    120. 133. Control Joints <ul><li>15’ typical-20’ max. </li></ul><ul><li>1:1.5 maximum aspect ratio </li></ul><ul><li>1/4D </li></ul><ul><li>Align with joints in plain concrete </li></ul><ul><li>No need to seal? </li></ul>
    121. 134. Effects of Joint Spacing 10.0 ft 3.0 ft 3.0 ft 3.0 ft Ultra-thin Slabs Deflect Concrete in Compression Standard Slabs Bend Concrete in Tension
    122. 135. Jointing Details
    123. 136. Control Joints <ul><li>Tooled </li></ul><ul><li>Saw-cut </li></ul>
    124. 137. Control Joints- Tooled <ul><li>Pizza Cutter </li></ul><ul><li>Thin blade, small radius </li></ul><ul><li>Don’t use traditional jointers </li></ul>
    125. 139. Control Joints- Saw cut <ul><li>Too early= raveling </li></ul><ul><li>Too late= ineffective </li></ul><ul><li>May hinder hydration </li></ul><ul><li>Cut at 7 days??? </li></ul>
    126. 140. Sealing Joints? Joints don’t need to be sealed, but sealant can reduce or eliminate raveling at joints
    127. 141. Construction joints <ul><li>Use thickened section or thickened edges for load transfer issues </li></ul><ul><li>If additional load transfer is needed, use traditional pavement </li></ul>
    128. 143. Isolation Joints <ul><li>Not expansion joints </li></ul><ul><li>Some debate over use </li></ul><ul><li>Proper installation critical to good performance </li></ul>
    129. 146. Panels
    130. 147. “ Natural” Construction/ Isolation Joints?
    131. 148. Transition to Asphalt
    132. 149. Header Curb
    133. 150. Where Pervious Concrete Abuts Conventional Pavement or Structures
    134. 151. Important Points for Design & Construction of Pervious Concrete <ul><li>Get a soils report </li></ul><ul><li>Determine thickness design based on usage, ADTT and soil type. </li></ul><ul><li>Determine base thickness based on design storm, soil type and flow concentration </li></ul><ul><li>Pay close attention to detail in methods and materials. </li></ul><ul><li>Use a contractor with NRMCA certified pervious concrete technicians. </li></ul><ul><li>Utilize industry resources – they are free!! </li></ul>
    135. 152. Pervious Concrete: Other Considerations
    136. 153. Striping
    137. 154. Integral Color
    138. 155. Stamping
    139. 156. Stained
    140. 157. Pervious Concrete- LEED 3.0 Considerations <ul><li>May Contribute to: </li></ul><ul><ul><li>SS Credit 6.1 Stormwater Design—Quantity Control (1) </li></ul></ul><ul><ul><li>SS Credit 6.2 Stormwater Design—Quality Control (1) </li></ul></ul><ul><ul><li>WE Credit 1 Water Efficient Landscaping (1-4) </li></ul></ul><ul><ul><li>MR Credit 4 Recycled Content (1-2) </li></ul></ul><ul><ul><li>MR Credit 5 Regional Materials (1-2) </li></ul></ul><ul><ul><li>Regional Priority Credits for SS 6.1 & 6.2 (1-2) </li></ul></ul><ul><li>May Detract from: </li></ul><ul><ul><li>SS Credit 7.1 Heat Island Effect—Nonroof </li></ul></ul>
    141. 160. Pervious Concrete Maintenance <ul><li>Design the installation with minimal exposure to sediment from other areas </li></ul><ul><li>Minimize the level of flow concentration </li></ul><ul><li>Sweep routinely as you would a parking lot of any other paving material </li></ul><ul><li>Set up periodic testing for infiltration capacity if a maintenance agreement is required by the approving agency </li></ul>
    142. 161. Prevent Runoff
    143. 162. Prevent Debris from Washing Onto Slab
    144. 163. Slope Grade Away from Pavement SWALE
    145. 164. Grade Pavement High
    146. 165. No Adjacent Dirt Parking
    147. 166. Islands/Vegetation
    148. 167. Routine Maintenance- Litter Removal <ul><li>Leaf blowers work well if done on a regular basis </li></ul><ul><li>Vacuum trucks effective at removing fresh deposited large debris </li></ul><ul><li>Sweeping not very effective </li></ul>
    149. 168. Routine Maintenance- Litter Removal
    150. 169. Vacuum Sweeping
    151. 170. Vacuum Sweeping
    152. 173. Removing Sediments <ul><li>Low pressure, high volume water </li></ul><ul><li>High pressure water usually not needed </li></ul>
    153. 174. Before and After Cleaning
    154. 175. Repair Work
    155. 176. Questions? For additional information or assistance, Please call or email: Sean Van Delist 210-883-8060 [email_address]

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