Pervious Pavement Webinar Speaker: Christy Martin, Executive Director Concrete Promotional Group, Inc. Moderator: Ryan Hamel Small Business Environmental Assistance Program Kansas State University Funding provided in part through U.S. EPA Section 319 Nonpoint Source Pollution Control Grant No. C9007405-08 administered by the Kansas Department of Health and Environment – Bureau of Water
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Kansas Small Business Environmental Assistance Program Environmental compliance assistance Multimedia (air, waste, water, energy, GHG inventory and reporting, EMS) WRAPS service provider Free to small- and medium- sized businesses (KDHE funded) Confidential Staff located throughout the state Contact Information: Web site: www.sbeap.org Hotline: 1-800-578-8898 Email: sbeap@ksu.edu
How it all fits… Kansas State University College of Engineering Engineering Extension Pollution Prevention Institute (PPI) • Small Business Environmental Assistance Program (SBEAP)
Pervious Concrete Pavements for Stormwater Mitigation
Pervious Concrete Pavement System Rain, Snow, Ice Pervious Concrete Gravel Base Geotextile Fabric Soil Subbase
What is Pervious Concrete? • Pervious concrete is a mixture of coarse aggregate, Portland cement, water, and little to no sand. A typical pervious concrete pavement has a 15-25% void structure and allows 3-8 gallons of water per minute to pass through each square foot. • Carefully controlled amounts of water and cementitious materials are used to create a paste that forms a thick coating around aggregate particles. Using just enough paste to coat the particles maintains a system of interconnected voids. • The result is a very high permeability concrete that drains quickly. Due to the high void content, pervious concrete is also lightweight, 100 to 120 lb/ft3. • After placement, pervious concrete resembles popcorn. Its low paste content and low fine aggregate content make the mixture coarse, with a very low slump. The compressive strength of pervious concrete is limited since the void content is so high. However, compressive strengths of 2000 psi to 4000 psi are typical and sufficient for most applications.
Why Use Pervious Concrete Pavements? • EPA, Phase II Directives, NPDES • Vertical Drainage vs. Horizontal Run-Off • Best Management Practice (BMP) • Drain Invert Filtration Systems – ELIMINATED • First Flush Pollution Mitigation – 90% of pollutants typically in Run- Off from the first ½” of rainfall • Add’l land purchase for detention ponds – NOT NEEDED • Air & Water get to tree roots & other vegetation • Pervious Concrete is a sustainable – green product • PC assists in gaining up to 3 LEED credit points • Parking Lot serves 3 purposes: 1) Parking Lot 2) Temporary Detention 3) Water Filtration
Pervious Concrete water passes at 3 - 5 gallons per min. per sq. ft. or 270 - 450 in. per hr.
Water Disappears Quickly
Pervious Concrete Applications • Parking Areas • Driveways • Sidewalks • Roadways • Swales & Ditches • Erosion Control • Slope Protection • More
Freeze/Thaw Concerns ? Why do water Freeze/Thaw pipes burst in Study cold weather? What will happen to these water bottles if left in a freezer a little longer? What would happen if the lids were taken off first before placing them in the freezer?
Freeze/Thaw Concerns ? All exterior concrete flatwork must have air entrained to the mix before it is placed to survive freeze/thaw conditions These pictures are concrete with no air entrainment
Air Entrained Concrete Cement content Without air With air 222 kg/m 3 (375 lb/yd 3 ) 306 kg/m 3 (515 lb/yd 3 ) 392 kg/m 3 (660 lb/yd 3 ) Air entrained concrete places microscopic voids throughout the concrete matrix to allow room for water to freeze & expand without tearing up the concrete!
Freeze/Thaw Concerns? • Pervious Concrete has air entrainment to protect the concrete at the mortar level (in the paste) • Pervious Concrete has air voids so large by nature you can see them • If water were to remain in the Pervious Concrete layer, there is plenty of room for water to expand 9% & not hurt the concrete • In most cases Pervious Concrete is more Freeze/Thaw friendly than regular concrete • Pervious Concrete has a base layer to allow the water to pass through and be retained in that base layer keeping the water away from the riding surface of Pervious
Clay Soil Concerns? 1. Research and experience show Rain, Snow, Ice us that water sitting in a base layer in clay soil conditions, Pervious Concrete typically looses ½ to 1 inch of water a day. 2. The Gravel Base Layer is adjustable! Reduce or increase the thickness depending on water retention needs. Gravel Base Calculate the typical rain event then calculate the volume the Geotextile Fabric base layer will handle. This is CLEAN ROCK typically ¾ in. up to 1 ½ in. Less than 2% on the Soil Subbase #200 sieve.
Typical Mix Design – Generic with 15 – 25% Void Structure • Portland Cement 500 - 600 lbs. ASTM C-150 – Type I or II Supplementary Cementious Mat’ls (Optional) Fly Ash Class C or F and/or Slag • Coarse Aggregates typically ½” to 3/8” > 2.5 specific gravity & < 2.5 absorption • Fine Aggregates – Usually none (Can have up to 6% sand in freeze-thaw markets for added durability) • Fibers (optional) Poly or Cellulose (No steel, no rebar or mesh) • Admixtures Water Reducers, Air Entraining Agents, HSA (hydration stabilizing admixture) Viscosity Modifying Admixture (optional) • Water w/c ratio of .27 - .33
Pervious Concrete Parking Lot Finley Football Stadium University of Tennessee Chattanooga
Pervious Concrete can be painted for parking stripes or handicap insignia
Pervious Concrete Sidewalk, placed in 2000 Owner: City of Olympia, WA 1500 lineal feet of sidewalk Sub-grade: native soil was permeable enough that an aggregate base was not needed Savings: $110,000 - land acquisition for detention ponds unnecessary
Testing Procedures: At this time there are no specific ASTM test procedures. ACI & ASTM are working on the Pervious Concrete Testing Procedures Unit Weight and Cured in Place Cored Cylinders are OK tests Specifications need to be very careful here. Advise to consult with John Kevern, UMKC
Pervious Concrete Certification is very important, please hire a Certified Ready Mix Company & Certified Contractor
Pavement Maintenance Approximately once a year or as needed: • Power Vacuuming • Pressure Washing (Careful!) • Combination of Both
Extremely Cold Weather Placement Careful! Can be done but needs extra special attention and should be avoided if possible Pervious Concrete Parking Lot Safeway Grocery Store Denver, CO Winter Placement, December 2004
Pervious Parking Lot Placed during the Winter Denver, CO, placed Dec. 2004 Notice that when snow is walked on the snow disappears into the pavement below.
Asphalt Lot across the street Pervious Concrete Parking Lot Denver – Next AM Following 12” Snow Sites directly across street from each other Photos: 5 min. differential max
Pervious Concrete Parking Lot & “Regular Concrete” Curb/Gutter & Sidewalk Notice the different pavements in the rain.
Mixed Concrete Products Pervious Concrete & “Conventional” Concrete To keep water out of storage units & mitigate stormwater management
Wal*Mart Pervious Concrete Parking Lot in McKinney, TX & Denver, CO
Slope Stabilization & Erosion Control Army Corps of Engineers Washington, MO
Decorative Pervious Concrete Driveway
Pervious Concrete Driveway
Pervious Concrete Tree Wells to get air & water to trees and for architectural beauty
Pervious Concrete Sidewalk
Pervious Concrete Parking Lot – Municipal Use City Park Parking Lot
Pervious Concrete Parking Lot Los Angeles, CA – Auto Auction Lot 90,000 sq. ft. of Pervious Parking
Pervious Concrete Parking Lot Tree Wells – Trees help it become a “COOL” pavement Trees & Plants get air & water through pervious pavements
Pervious Concrete Drive Lane Florida Shopping Center, Delivery Truck Drive Picture taken 12 yrs after placed
Pervious Concrete Parking Lot Tampa, Florida Aquarium - 8 years old
Pervious Concrete Parking Lot Brandon Regional Hospital Brandon, Florida Picture taken 14 yrs after placed
Pervious Concrete Pavements Big Jobs & Little Jobs
Pervious Concrete Parking Lot Rock base being delivered Placing on top of geotextile fabric
Pervious Concrete Parking Lot Clean Rock Base Placed over Geotextile Fabric Notice Curing Blankets in Background
Pervious Concrete Placement Telebelt Placement works nicely Pervious will not Pump!
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