Pervious Concrete Pavement Strength: 400-4,000 psi (2.8-28 MPa) Pavement Design Pervious concrete is...
125
Pervious Concrete Pavement Robert Rodden, P.E. Senior Director of Pavement Technology
Transcript of Pervious Concrete Pavement Strength: 400-4,000 psi (2.8-28 MPa) Pavement Design Pervious concrete is...
Pervious Concrete Pavement
Robert Rodden, P.E.
Senior Director of
Pavement Technology
Acknowledgments
John T. Kevern, PhD, PE, LEED AP – U of M, KC
ACI 522 members
ACPA Chapters across the U.S.
Carolinas Ready Mixed Concrete Association
PCA – Northeast
Washington Aggregates & Concrete Association
Etc…
What is This Stuff?
Pervious Concrete Pavement
What is Pervious Concrete?
Concrete with sufficient interconnected
voids to allow water to pass through it
Near zero slump
Open graded
Coarse aggregate, cement,
admixtures and water
Little or no fine aggregate
Also called “no-fines concrete”
Conventional Concrete
Pervious Concrete
What is Pervious Concrete?
Where Did it Come From?
1852 – used in home
construction
Caught on after WWII Thousands of houses built this
way in UK, Germany, Holland,
France, Belgium, Scotland,
Spain, Hungary, Venezuela,
West Africa, the Middle East,
Australia, Russia, etc.
Up to 10 stories tall!
Houses in Toronto and federal building in Ottawa
…Back to Pavements
Pervious Concrete Pavement
Pervious Concrete Pavement
Used in US for over 40 years! Initial applications
(FL, GA, WA, & OR) were for flood control.
1987 Clean Water Act and NPDES brought it into
use for control of urban runoff
NOTE: NPDES = National Pollution Discharge Elimination System
Pervious Concrete Pavement
A system consisting of:
A high permeability pervious concrete surface
A subsurface storage area w/ or w/o an underdrain
A supporting soil column
What are the Advantages
and Disadvantages?
Pervious Concrete Pavement
Advantages
Controls stormwater pollution
at the source
Controls stormwater runoff
Calverton, N.Y.
Advantages
Water quality improvement
SA
ND
FILTER
PER
VIO
US
CO
NC
RE
TE F
ILTER
www.h2ohow.com
Advantages
ACI 522R-10
http://cfpub.epa.gov/npdes/stormwater/menuofbmps/index.cfm?action=browse&Rbutton=detail&bmp=137.
From ACI 522 Minutes Fall 2012 in Toronto: “Use of enzymes and bugs to attack pollutants within pervious was discussed.”
Advantages
Tree protection
Advantages
Noise reduction
Modi-slab, pervious concrete roadway in Netherlands
Advantages
Splash/spray, slip/fall, and glare reduction
MnROAD – Minnesota DOT Walmart – Nashville, NC
Advantages
Improved friction and skid resistance
Advantages
Urban heat island mitigation
Advantages
More area to develop
Source: EPA-821-R-99-012
Disadvantages
Design
Limited use w/ heavy traffic
Special attention w/ impermeable, expansive, or frost-
susceptible soils
Special attention w/ high water table
Special attention w/ freeze-thaw environment
Construction
Specialized construction practices
Extended curing time
Sensitivity to water content and control in fresh concrete
Not as many/improperly used standards
What Applications Might
Consider Pervious?
Pervious Concrete Pavement
Parking Lots
Parking Lots
Parking Lots
Parking Lots
Parking Lots
Low Volume Roads
Shoulders
Driveways
Alleyways
Wearing Course Overlays
…can be for drainage, noise mitigation, etc.
Underdrain
Lambert International Airport, St. Louis
The base under all the runways is pervious concrete
Sidewalks
Recreation Trails
Car Dealerships
Fire Stations
Odds and Ends
Swimming pool decks, greenhouse floors, reefs, etc…
… and Even Stairs and Patios!
Design
Pervious Concrete Pavement
Design Considerations
Mixture design
Pavement design
Hydrologic design
Hydraulic design
Basic Mixture Proportioning
Balancing act between aggregate, paste, water,
admixtures, and void space
Air-entrained paste
Aggregate
Voids
Aggregate
Paste
Traditional
Concrete
Aggregate
Paste
Pervious
Concrete
Mixture Design Considerations
Ultimate goal is a smooth, uniform surface with required
porosity/voids to provide strength (durability) and
permeability, which can be related to unit weight
We can achieve our design porosity by either a workable
mixture or applying more compaction energy
Main Factors: agg. shape, agg. gradation, binder content,
w/c, admixtures
0.00
0.50
1.00
1.50
2.00
2.50
10 15 20 25 30 35 40
Concrete Voids (%)
Pe
rme
ab
ilit
y (
cm
/se
c.)
3 in.
4 in.
(c) Porosity, %
CL5 2
1 3
4
0.00
0.50
1.00
1.50
2.00
2.50
10 15 20 25 30 35 40
Concrete Voids (%)
Pe
rme
ab
ilit
y (
cm
/se
c.)
3 in.
4 in.
(c) Porosity, %
CL5 2
1 3
4
Each mixture has an inherent set of well-defined compaction relationships, allowing QC/QA based on unit weight
Perm
eability,
cm
/s
R 2 = 0.997
90
95
100
105
110
115
120
125
130
10 15 20 25 30 35 40
Concrete Voids (%)
Un
it W
eig
ht
(pcf)
U
nit W
eig
ht, p
cf
(a) Porosity, %
Compaction Level (CL)
CL5
2
1
3
4
R 2 = 0.997
90
95
100
105
110
115
120
125
130
10 15 20 25 30 35 40
Concrete Voids (%)
Un
it W
eig
ht
(pcf)
U
nit W
eig
ht, p
cf
(a) Porosity, %
R 2 = 0.997
90
95
100
105
110
115
120
125
130
10 15 20 25 30 35 40
Un
it W
eig
ht
(pcf)
U
nit W
eig
ht, p
cf
(a) Porosity, %
Compaction Level (CL)
CL5
2
1
3
4
0
500
1,000
1,500
2,000
2,500
10 15 20 25 30 35 40
7-d
ay f
c' (p
si)
¦ ’ c
,7 - d
, p
si
(b) Porosity, %
CL5
2
1
3
4
Typical Mixture Characteristics
Agg: single-sized coarse or grading between ¾-3/8 in. (19-9.5
mm), rounded or crushed @ SSD
Most common: ASTM C33 sizes 7, 8, 67, and 89
Aggregate: 2,000-2,500 lb/yd3 (1,190-1,480 kg/m3)
Cementitious Content: 450-700 lb/yd3 (270-415 kg/m3)
Pores: 0.08-0.32 in. (2-8 mm)
Voids: 15-35%
Permeability: 192-1,724 in./h (0.14-1.22 cm/s)
w/cm: 0.26-0.45
Comp Strength: 400-4,000 psi (2.8-28 MPa)
Pavement Design
Pervious concrete is a rigid pavement and
structurally is designed the same as conventional
concrete
Note: The base will be saturated so use a soaked
CBR for the soil strength
ACPA’s PerviousPave
software is based on
StreetPave’s fatigue
equations
Absent Distress Failure Criteria
Surface Distress: No prediction models…yet
Resistance of surface controlled by
materials/construction
Consistent with approach on material-related
distresses in other structural design methods
Faulting: Does it happen?
Pavement Design Considerations
Permeability of soil should be verified:
Percolation rate of 0.5 in./h (13 mm/h) and a soil layer
of 4 ft (1.2 m) or more are generally recommended
Typical Pavement Designs
This is as loaded as questions come; depends on
the application, soil conditions, mixture, etc.
Pervious concrete generally 6 to 12 in. (150 to 300
mm) for street or road
Have to balance hydro
concerns with thickness
of surface and reservoir
layer(s) and also storage
location requirements
(e.g., freeze-thaw)
Hydrologic Design
Potential goals: reduce runoff volume, reduce
treatment volume, reduce impervious area
Flat base ideal
For more on stormwater BMPs see: www.epa.gov/waterscience/stormwater
Storage Capacity
Design storm: 25 yr, 24 hr storm ~ 4.5 in. (assume base
to hold all 4.5 in. of water)
Reservoir layer void space = 40%,
Required thickness = 4.5 / 0.4 = 11.25 in., say 12 in.
Natural soil infiltration rate ~ 1 in./day = 12 days to empty
Generally, you don’t want water in the base for more than
48 hours so an underdrain
is necessary
Full Exfiltration
Jones 2008
DO NOT OVERCOMPACT SUBGRADE!
Partial Exfiltration
Jones 2008
No Exfiltration
Jones 2008
Hydrologic Design
French
Drains Check
Dams
Terraces
See PCA EB303 for more…
POOLING IS BAD
Constructability is Important
Typical Details
ACI 522 has balloted some new details
Hydraulic Design
All permeable pavements are filters; filters remove
particles
Related to size of hole in filter, size of filtered
particle, amount of particles, velocity of fluid, etc.
Hydraulic Design
Also concerned with run-off versus infiltration
This is dependent on cross slope of pavement
Hydraulic Design
Simple approach* from field testing/evidence: 0:1 impervious to pervious > 500 in./hr
1:1 impervious to pervious > 1000 in./hr
2:1 impervious to pervious > 1500 in./hr
3:1 impervious to pervious > 2000 in./hr
4:1 impervious to pervious > 2500 in./hr
We still don’t know the typical and
allowable variability, so “hard”
design values are not yet specified!
Testing
Not our usual suite of concrete pavement tests
ASTM C09.49 is developing pervious tests
Comp strength is not used for acceptance. There is a wide range of strengths possible b/c of the relationship with compaction.
Available Tests
ASTM C1688 – Standard Test Method for Density
and Unit Weight of Freshly Mixed Pervious
Concrete
Controls mixture consistency; predictor of in-place voids, permeability, and strength
Available Tests
ASTM C1701 – Standard Test Method for
Infiltration Rate of In-Place Pervious Concrete
Predicts clogging and verifies design criteria
Available Tests
ASTM C1747 – Standard Test Method for
Determining Potential Resistance to Degradation
of Pervious Concrete by Impact and Abrasion
Predicts abrasion resistance
Available Tests
ASTM C1754 – Standard Test Method for Density
and Void Content of Hardened Pervious Concrete
100% 57 = 36% voids
100% C33 sand = 35% voids
Allows verification of in-place density and consistency
Other “Non-Standard” Tests Exist
Too Wet
Sufficient Consistency
Other Tests Being Developed
For example, surface raveling resistance and
effectiveness of curing procedures
Freeze-Thaw Resistance
Precautions to enhance freeze-thaw performance:
Use an 8-24 in. (200 to 600 mm) thick layer of clean
aggregate base below the pervious concrete
Use air-entraining admixtures
Place perforated PVC pipe in the aggregate base and
drain water away from structure
Consider adding a small amount of sand to the
mixture
SCMs, fibers, liquid polymers, etc. can help too
Construction
Pervious Concrete Pavement
Construction Considerations
Need a good starting mixture design
Good quality rock, good quality admixtures, fibers
don’t hurt, and maybe some sand
Need proper delivered workability, so you can:
Place to the desired density
Too high it clogs, too low it ravels
Cure quickly and sufficiently
Pervious dries quickly; increased raveling potential
Protect from damage caused by other construction
traffic and runoff during and after curing
Reservoir Layer / Underdrain
This Layer might be very Thick!
Set Forms
Dampen the Subbase
Concrete Placement
Can be placed with a conveyor – not a pump
Color / Stain / Stamp Are Optional
Tools of the Trade
Tools of the Trade
Moving the Concrete (as necessary)
See any construction concerns?
Roller Screeding
Construction Methods Vary
Compact
Riser strips may or may not be used.
Mind the Surface
vs
Edges can be Tricky!
Edge as Required
Cover with Plastic ASAP!
10 ft.
Jointing
Jointing
Jointing
What about Longitudinal Joints?
Remove Forms…
…and CURE, CURE, CURE!
7 days for just cement mixtures; 10 days if SCMs used.
SCMs might affect curing!
AGAIN – Cure, Cure Cure!
Well secured poly, stapled to wood form, 2x4’s nailed to form
Plastic Only Works if Edges Sealed
GOOD
BAD
… or Internal Cure
Internal Curing of Concrete
Supplying additional water internally can mitigate
shrinkage stresses in low w/c mixtures
Saturated lightweight aggregates, saturated
porous aggregates, super absorbent polymers,
etc. can supply this extra internal water
Grind if Required for Smoothness
Maintenance
Pervious Concrete Pavement
Think about During Design
Prevent driving from unpaved to pervious
Do not lay in path of wind nearby beach
Limit stormwater flow from adjacent nonpervious
and landscaped areas
Landscaped areas at lower elevations
Expected Maintenance
Permeability Maintenance
Routine Cleaning
Clogging
Winter Maintenance
Plowing
Salting/sanding
Pavement Distress Remediation
Before Cleaning
After Cleaning
***The Key for Designers, Contractors, and Owners:
These are both pavements and BMPs so maintenance
will be a hybrid.
Have a Maintenance Plan!
Permeability Maintenance
Winter Maintenance
Salt similar to conventional concrete pavement; not in the
first winter (probably will use much less salt overall)
Sand not needed for pervious (sand will reduce
permeability so it will need to be swept out if used)
Plowing similar to conv.
conc. but be aware it
is a different surface
(no back dragging
with a bobcat)
Winter Maintenance
Winter Maintenance
Salt and sand required Nothing required
Pavement Distress Remediation
Other Notable Installations
Pervious Concrete Pavement
Pervious OL on RCC in Japan
Lowe’s – Kill Devil Hills, NC
US EPA Parking Lot – Edison, NJ
US EPA Parking Lot – Edison, NJ
Chicago Alleys
Industrial Park - NJ
9th
Ward in New Orleans
McGuire AFB Hangar, NJ
Denver – Day after 12” snow
Photos taken directly across street from each other and 5 min apart
Entrance to Pet Resort, NJ
Fish Hatchery – Philadelphia, PA
Costco – Wilmington, NC
Subway Headquarters – Milford, CT
Cost
Pervious Concrete Pavement
Cost Considerations
Serves as several products in ONE
Parking lot
Collection system
Filter
Temporary detention
Difficult to give SY cost
because very
dependent on thickness of each layer,
experience of contractors, etc.
Cost
- Pavement materials cost ~8-15% more than
traditional concrete pavement
- Extra material in aggregate base
- Additional installation costs in most cases
+ Reduced or eliminated detention/retention
+ Reduced stormwater infrastructure
+ Improve site utilization (purchase less, sell more,
more taxes)
Must evaluate each project separately!!
Discussion/Questions?
Main Website | acpa.org Free Apps | apps.acpa.org
Resources | resources.acpa.org Your Local Contact | local.acpa.org
Robert Rodden, P.E.
Senior Director
of Pavement Technology
847.423.8706
EDUCATION NEVER ENDS
