Mix Designs and using ASTM standards to ensure a high ...ACI 522 ACI 522. Inside the drip edge – typically can’t be done; standard design 6” pervious, 6” base – base depends
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Mix Designs and using ASTM standards to ensure a high-quality final Pervious product Walt Flood IV, M.S., P.E. IRMCA XXXtreme, 2018
Who doesn’t know about pervious concrete; producers, contractors, testers, everybody else
•Who is Flood Testing
•Pervious Concrete Overview
•Pervious Concrete Mix Designs
•Pervious Concrete Testing-The ACI Guide way
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Presentation Notes
The ACI 522R state of the art document – QC chapter reorganized in most recent version; photo shows bunch of unique applications – base for pavers, cheap and bony covered, grouted edges
Flood Testing Labs (FTL) was founded byWalter Flood in 1913 as one of the firsttesting labs in the Midwest.
• Located on the south side of Chicago
Walter Flood III and WalterFlood IV are PE’s in multiplestates
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Tell story of FTL – Fire buildings falling
General Material Testing Services and Consulting
• High Strength Concrete• High Modulus Concrete• Thermal Control Plans• Maturity Monitoring• NRMCA certifications• Pervious and RCC Testing• Special Performance Mixes• Failures
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Presentation Notes
Mix/ retardation problems on project in Miami, FL; do a lot of slump tests, but like to keep busy with more interesting things
What is Pervious Concrete?-ACI 522:
“hydraulic cement concrete proportioned with sufficient, distributed, interconnected macroscopic voids that allow water to flow through the material under the action of gravity alone”
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Explain my thoughts of pervious – aim for 18-22% voids; what happens to concrete strength when you add 5% to 10,000 psi concrete?? use high strength high density paste – results in a fragile void structure held together by sensitive paste
Why is Pervious Useful?
Low Impact Developmenti.e…. it can save us money• Reduces stormwater volumes• Naturally cleans and filters water• Can be used for water collection/recycling• Reduces urban heat island effect• Safer surface (skid resistance)• Eliminate Retention Ponds• Provides a means to obtain
LEED credits
•Makes a great fire pit
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Majority of Suspended solids and heavy metals are either trapped or grabbed by the pervious while passing through the tortuous void system; after month and half, bacteria colony, same as in a fish tank that consumes volatile organic compounds and other organic matter; eliminate the requirement for de/retention ponds; stone is temporary detention basin limited by perc rate of soils below or other system parameters as designed
How is Pervious Pavement placed?-Placed in strips and compacted
typically with roller screed-Immediately covered
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Both show single stage with roller screed; provides compaction from weight and counter-rotating drum and strikeoff with forms; some markets use two step – strike off with spacers about 3/8” high, then use static roller to compact; New Mexico use a vibratory plate to compact; placed in strips of approx 20’ max
What is Pervious Pavement?
-Typical Sections
ACI 522
ACI 522
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Inside the drip edge – typically can’t be done; standard design 6” pervious, 6” base – base depends on storage, pervious depends on use – pedestrian or loaded concrete trucks?
Not this simple!
-Zero fines
-Zero slump
-Standard concrete, take out the fines, remove some water and give it a try
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Used to be more like the bottom, take out the sand, take out the water; ASTM oops
Pervious Concrete Requires…
…a producer to get in the lab…a contractor to spend some money…a mockup/ test placement…jobsite adjustment with water…7 day cure…covering with plastic…consider the weather…recurring maintenance
Which is why so many screw it up!
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Pervious must be treated differently from regular concrete! More like asphalt – development in lab ahead of time; contractor needs training and some trial placements (Raffin put down thousand yards in their yard…)
More workable-More design work dialing in the
gradation and laboratory properties
-Smaller Topsize
-6-8” slump
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Wet, Metallic Sheen!! It Slumps!
All starts from the aggregate
Dry-Rodded Unit Weight (ASTM C 29)
Used to determine free voids in aggregate - Provides baseline for mix
designs- Get idea of range of voids
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Void range – dry rodded isn’t necessarily the answer – what is range between loose and max (beat up, vibrated); unfortunately, ACI 522 doesn’t currently produce anything use-able
Empty Cubic Yard
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unfortunately, ACI 522 doesn’t currently produce anything use-able; mixes often come from the voids side – okay I need 20% voids, how to I get there -> wrong angle
Void space
Solid Aggregate
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Agg could be 1.5” stone, could be #8, doesn’t matter – follow the same general process
Void spacePaste
Solid Aggregate
Paste = Water, Cement, Sand (etc.)
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unfortunately, ACI 522 doesn’t currently produce anything use-able; mixes often come from the voids side – okay I need 20% voids, how to I get there -> wrong angle
Technically, don’t need any more than water, cement; w/c typ 0.35-0.38
• Hydration stabilizer highly recommended• Some #8-#16 sand increases freeze-thaw
durability• Fibers big help – macro• AE – can’t hurt• Microsilica – dense paste• Viscosity Modifiers• SAP, internal cure, MRWR
Matt Offenberg
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Detail them on following slides
Divided into 3 major Groups:as re-organized in 522R (publish date TBD)
• Preconstruction/ mix development
• Construction testing
• Post Construction Evaluation
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522R being revised and updated by ACI now – hopefully publish in 2018?? Burn marks are water tubes – when doing whatever you want, a gas pipe isn’t enough
•Testing Ideal:To measure the in-place properties of the material without damaging it,or create a specimen that can be tested that perfectly mimics the material as it is in place
•Method affects resultsDensity example
David Mitchell
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REALITY – most of the time establish a standard method unrelated to in place; Density: Two specimens, you take one and dry it in an oven at 120 F for 3 days, I take one and dry it at 400 F for 3 days – mine says the placement fails – density too low; about 2% differences, 54 C, 110 C, vacuum saturated
David Mitchell
Four ASTM standards relating directly to pervious testing
• C1688 Fresh Density and Void Content
• C1701 Field Infiltration Rate
• C1747 Raveling Potential
• C1754 Hardened Density
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Detail them on following slides
(also test panel placement)
Aggregates-Dry-rodded
Unit Weight (C 29)
Confirmation/Choosing a Mix-Raveling Potential (C 1747)-Infiltration-Void-Density Curve (C 1688)-Tensile and Compressive Strength-Inverted Slump Cone-Gyratory workability - ?
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Black stuff – asphalt; take cores on asphalt – how many test the strength of those cores?? 0! Everything is tied to density! Inverted slump cone – for those who haven’t seen much pervious, can usually see it in your hand
Void-Density Curve (ASTM C 1688)
Used to create a Curve to control Quality-Identify target C 1688 Density ranges
Very useful during placement
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Make sure this doesn’t contradict the spec – random spec numbers with
Move towards lab-only tests?•Gyratory Compactor•From Asphalt industryactually replicates rolling
Use to determine mix properties-Correlate in Field with Density
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Tie to strength, durability – everything!!
Best Practices-Density and
Unit Weight (C 1688)
Experimental-Nuclear
Density(is this really Post-Placement?)
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PLACEMENT – everything is tied to density = strength, infiltration, durability…
ASTM C1688 - “Density and Void Content of Freshly Mixed Pervious Concrete”
-Standard Air Meter Bucket
-Compaction using Proctor hammer or Marshall Hammer
-Two lifts 20 blows or two lifts 10 blows
-For set mix, will provide measure of consistency
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Spearheaded by Michael Davy with Cemex – was first pervious test method
Fresh Density (ASTM C 1688)
-Target fromtest panel
Compare to Void-Density Curve-If outside the range, remedy truck-Frequency of testing?
The PRIMARY means of control during placement
Walter H Flood III
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Recommending every truck for smaller placements, beginning or placements, and not-too-large placements. Get a feel for it, consistency, reduce amount. Require for first 5 trucks, every 50 yards there-after? +/- 3 lbs from target is very doable – on dry days, slow placement, or inconsistent supplier, can require adjusting mid-truck (smaller loads?); 1016 W Jackson, condo parking
Nuclear DensitySimilar to ASTM D 2950 (asphalt), ASTM D 6938 (soils)•Backscatter through plastic•Provides moisture and density
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Won’t work with most good mixes because will mark the concrete – but would work a few days later for acceptance
To confirm compliance and monitor performance
-Infiltration (C 1701)-Density and Void Content (C 1754)
or Nuclear Density
David Mitchell
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Left, Vegas, Perv Master’s Ball; right is Raffin’s Lot
ASTM C1701 – “Infiltration Rate of In Place Pervious Concrete”
-Nominal 12” Diameter Collar-Maintain .5” head of water (+/- .1”)-Presoak with 8 lbs (1 gallon)-Test with 8 lbs or 40 lbs (1 or 5 gal)
Recommending all Contractors performCYA!
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Spearheaded by Dr. Heather Brown of Middle Tennessee State University; if 1 gallon in presoak takes less than 30 seconds, use 5 gal, otherwise use 1 gal; started using ring from dual ring infiltrometer – a bit high and hard to maintain head – use a short piece of 12” PVC; Contractors perform when pull the plastic – provide to owner as a baseline – prove you did your job and when they come back 8 months later after their landscaper dumped 3 yards of topsoil onto the pavement, have proof you did your part
ASTM C1701 – “Infiltration Rate of In Place Pervious Concrete”
-Intended to indicate clogging
Provides direct measure of water flow
-Highly variable across single placement
-Need lots of testsDavid Mitchell
Presenter
Presentation Notes
intended as qualitative method to monitor the degree of clogging of a pavement but incorrectly stated that is not for compliance – that was taken out of ASTM; below 150 in/hr start to have issues – most of ours go in around 1200 in/hr. Better Qualitative rather than quantitative; can see 30% variation in a good pavement
ASTM C 1754 – “Density and Void Content of Hardened Pervious Concrete”
-Using 4” specimen-Trim to regular dimensions
-Dry to constant mass-Method A – 50C-Method B – 95C
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Spearheaded by Walter IV, Flood Testing; intentionally vague on the specimen – intent is to provide a standard method to determine voids and density; leave to ACI to determine how many cores for acceptance; still want to use for research with cast cylinders as well
Hardened Density and Voids (ASTM C 1754)
Provides standard method for Density and Voids
-ACI 522.1 requires 3 cores per 5000 sqft
-Compare to resultsfrom TEST PANEL
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2 methods – 100 F and 230 F. Pick a method and use it for trial and placement. About 2% different; usually 6-7% higher voids than fresh density for our mixes, but depends on contractor and mix
Pervious Concrete maintenance-Issues at < 75 in/hr-Regain up to 95% infiltration with
pressurewasher and vacuum
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Permeable pavers at 70 to start; shoot for 500-1000 in/hr at install – density/void tradeoff
Scott Erickson
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2 methods – 100 F and 230 F. Pick a method and use it for trial and placement. About 2% different; usually 6-7% higher voids than fresh density for our mixes, but depends on contractor and mix
With proper work on the front endQuality Pervious is REAL!!
Thanks especially to:Brian Lutey, Ozinga Green BuildingDave Mitchell, Bunyan IndustriesJim Miller, C2 ProductsDr. John Kevern, UMKCScott Erickson, Evolution Paving ResourcesFlood Testing Laboratories, Inc.
Brian Lutey
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Pervious must be treated differently from regular concrete!
