Permeable Interlocking Concrete Pavement
Design & Construction
Rick Crooks,
Director of Business Development
Mutual Materials Co.
Bellevue, WA
425-922-7370
[email protected]
Intermediate
LID Design
Module 3.3
Seattle, WA
16 October 2014
Pendleton Blvd, JBLM
courtesy Mutual Materials Co.
Content:
Design Information
•Sources
System Components
•Pavers
•Aggregates
•Edge Restraints
Construction
PICP Sections
Structural considerations
Percival Landing Park, Olympia
courtesy Mutual Materials Co.
Interlocking Concrete Pavement Institute
www.icpi.org
PICP ‘Design Manual’
– Fourth edition
•Design
•Specifications
•Construction
•Maintenance
Design software:
“PICP Permeable Design Pro”
Balances system performance
•Structural support
•Hydraulic capacity
•Uses single event model
Design Details
Guide Specifications
Videos
Technical Research
Papers
System Components
courtesy of ICPI
the “wearing course”
“Permeable” Interlocking Concrete Pavers
courtesy of ICPI
Paver units
themselves are
not permeable
Permeability
comes from wide
joint spacing
and/or openings
in the pavers
Typical Paver Shapes for PICP
Drainage joints
Drainage ‘features’ or shape
courtesy of Uni-Group USA
courtesy of Mutual Materials
“Permeable” Interlocking Pavers
ASTM C936:
Standard Specification for Solid Concrete
Interlocking Paving Units
Note… the physical property requirements for permeable
paving units are the same as impermeable paving units:
•Maximum face area = 101 sq. in.
•Minimum thickness = 2.36 in. (60 mm)
•Minimum Compressive Strength = 8,000 psi
•Maximum 24 hr. cold water absorption = 5%
•Freeze-thaw durability per ASTM C 1645
•Abrasion resistance
•Dimensional tolerance
Aspect ratio (L:T) guidelines apply –
• 4:1 pedestrian only (ASTM reqm’t)
• 3:1 to 4:1 for residential driveways
• 3:1 or less for all vehicular areas
Additional paver considerations:
courtesy of ASTM
“ADA” Requirements
302 Floor or Ground Surfaces
302.1 General. Floor and ground
surfaces shall be stable, firm, and slip
resistant and shall comply with 302.
Advisory 302.1 General. A stable
surface is one that remains unchanged
by contaminants or applied force, so that
when the contaminant or force is
removed, the surface returns to its
original condition. A firm surface resists
deformation by either indentations or
particles moving on its surface. A slip-
resistant surface provides sufficient
frictional counter-force to the forces
exerted in walking to permit safe
ambulation.
“ADA” Requirements
302.3 Openings. Openings in floor or ground surfaces shall not allow
passage of a sphere more than ½ inch (13mm) diameter except as
allowed in 407.4.3, 409.4.3, 410.4, 810.5.3 and 810.10. Elongated
openings shall be placed so that the long dimension is perpendicular to
the dominant direction of travel.
“ADA” Requirements
303 Changes in Level
303.1 General. Where changes in level are permitted in floor or ground
surfaces, they shall comply with 303.
303.2 Vertical. Changes in level of ¼ inch (6.4 mm) high maximum
shall be permitted to be vertical.
“ADA” Requirements
303.3 Beveled. Changes in level between ¼ inch (6.4 mm) high
minimum and ½ inch (13 mm) high maximum shall be beveled with a
slope not steeper than 1:2.
System Components
courtesy of ICPI
Paver Joint fill Aggregate
Free-draining (“open-graded”) aggregate that complies with
the gradation requirements of ASTM D 448, No. 8:
courtesy of ICPI
Note… if No. 8 aggregate is not available, industry recommendations
are to use No. 89 or No. 9 stone.
Aggregates for use with PICP
In addition to the gradation requirements for joint filler,
bedding layer, base and subbase, all aggregates should
be:
– Crushed stone
• 90% fractured faces
• Do not use rounded river rock!
– Hard, durable material
• LA Abrasion < 40 per ASTM C131
• min. CBR of 80% per ASTM D1883
– No fines
• Less than 2% passing the #200 sieve
System Components
courtesy of ICPI
Bedding Course Aggregate
Free-draining (“open-graded”) aggregate that complies
with the gradation requirements of ASTM D 448, No. 8:
courtesy of ICPI
Other names for ASTM No. 8: ¼” clear crushed; 3/8” clear
crushed; ¼ – 10 clear crushed
Sieve Size
No. 8
No. 89
No. 9
½ in. (12.5 mm)
100
3/8 in. (9.5 mm)
85 to 100
90 to 100
100
No. 4 (4.75 mm)
10 to 30
20 to 55
85 to 100
No. 8 (2.36 mm)
0 to 10
5 to 30
10 to 40
No. 16 (1.16 mm)
0 to 5
0 to 10
No. 50 (0.30 mm)
0 to 5
Bedding & Jointing
Jointing
Jointing only
only
Washed material: percent passing No. 200 (0.075 mm) sieve < 2%
System Components
courtesy of ICPI
Base Course Aggregate
Free-draining (“open-graded”) aggregate that complies
with the gradation requirements of ASTM D 448, No. 57:
courtesy of ICPI
Other names for ASTM No. 57: 1-1/2” clear crushed drain
rock; 1-1/4” clear crushed drain rock.
System Components
courtesy of ICPI
Subbase Course Aggregate
Free-draining (“open-graded”) aggregate that complies
with the gradation requirements of ASTM D 448, No. 2:
courtesy of ICPI
Other names for ASTM No. 2: Permeable ballast or railroad
ballast
Again….aggregates for use with PICP
In addition to the gradation requirements for joint filler,
bedding layer, base and subbase, all aggregates should
be:
– Crushed stone
• 90% fractured faces
• Do not use rounded river rock!
– Hard, durable material
• LA Abrasion < 40 per ASTM C131
• min. CBR of 80% per ASTM D1883
– No fines
• Less than 2% passing the #200 sieve
Edge Restraints
Edge Restraints Application Guide
Commercial Vehicular
Cast-in-place concrete
Precast concrete
Cut Stone
Pedestrian & Residential Driveways
All of the above
Compacted base at perimeter with spiked edging
Pedestrian Only
All of the above
Geogrid & edging
Edge Restraint Guidelines
Commercial Vehicular
Cast-in-place concrete – straight curb or
curb & gutter, precast concrete, cut stone
Drain to bioswale
Curb depth to bottom of asphalt
dense-graded base
Yes
Edge Restraint Guidelines
Pedestrian & Residential
All of the above
Compacted dense-graded base at perimeter
with spiked edging
Dense-graded edge berms
Open-graded base
Residential driveway with
compacted base sides
Compaction
Setting/checking grades
Edge base contains bedding
Screeded bedding & layout
No. 8 stone
Dense-graded base along edges
Alignment
Compaction
Filling openings
Plastic edge restraint examples
Final sweeping
Joints filled
Edge Restraint Guidelines
Pedestrian Only
All of the above
Geogrid & edging….
Troweled Concrete Edge Restraint
Geotextiles
• Option of the design engineer
• Non-woven recommended (high water flow)
• AASHTO M-288 provides minimum requirements
• AOS selection criteria in PICP manual
• Or use manufacturer’s recommendations
• Place on sides & bottom
• Minimum overlap 12 in. (0.3 m)
• Poor soils overlap 24 in. (0.6 m)
• AASHTO M-288
o Tables 1 & 2: Strength & Subsurface Drainage Geotextile
Requirements
Geotextile (optional)
Pre-Installation
Material Access & Flow
Contamination of permeable
surface and aggregates
Good practice: Keeping dirty
tires off of PICP surface!
Other material placement
and movement options?
Dumping the near
end first: avoid truck
tires compacting the
soil subgrade
Construction
Sequence
Open-graded base storage
Geotextile under pile
Or place on impervious surface
Contaminated base
or bedding
must be replaced!
Construction practices….
Don’t store on soil
Good housekeeping
Open-graded base storage
Mechanical or Manual Installation?
• Most important: available paver pattern
• Cost & time savings
• Site access
• Area
Stitching required in
herringbone patterns
Pattern requires full pavers only
Pattern requires moving half stones
Mechanical Installation
Mechanical installation of PICP can decrease
construction time 20-80% over manual installation
Manual paver installation:
approx 1,000 sq. ft. per man per day
Mechanical paver installation:
3,000 – 10,000 sq. ft. per machine per day
Weather….
Install Subbase
& Base Materials
Gradation Comparison
Open-Graded Aggregate Gradation
Sieve Size
% Passing
No. 2
No. 57
3 in. (75 mm)
100
2.5 in. (63 mm)
90 to 100
2 in. (50 mm)
35 to 70
1.5 in. (37 mm)
0 to 15
100
1 in. (25 mm)
95 to 100
3/4 in. (19 mm)
0 to 5
1/2 in. (12.5 mm)
25 to 60
No. 4 (4.75 mm)
0 to 10
No. 8 (2.36 mm)
0 to 5
Subbase:
ASTM No. 2 Crushed Stone
Base:
ASTM No. 57 Stone
No. 2 & 57 Stone Not Available?
Other stone sizes okay – selection criteria:
Min. void ratio = 32%, min. 90% fractured faces, LA
Abrasion Loss < 40
Layer choke criteria:
D15 base stone /D15 bedding stone < 5
D50 base stone/D50 bedding stone > 2
Dx = particle size at which x percent of particles are finer
Example: D15 = aggregate particle size which 15% are
smaller and 85% are larger (by weight)
Note…read D15 and D50 on sieve analysis report
Subbase and Base:
Delivery, Installation & Compaction
• Moisten stones
• Lift thicknesses
o Subbase (No. 2 stone or similar):
Max. 6 in. lifts
o Base (No. 57 stone or similar):
One 4 in. lift
Compaction
Roller compactor – 10 T steel vibratory
First two passes in vibratory mode
Last two in static mode until no visible stone movement
Plate compactor – 13,500 lbf (60 kN) min. 2 passes
Density verification methods
Installing Bedding & Jointing Materials
• Bedding: ASTM No. 8 stone – chokes into No. 57
• Joints: ASTM No. 8, 89 or 9 stone
• Similar gradations acceptable
• Maximum joint width drives jointing material
selection
Gradation & Base Capability
Sieve Size
No. 8
No. 89
No. 9
½ in. (12.5 mm)
100
3/8 in. (9.5 mm)
85 to 100
90 to 100
100
No. 4 (4.75 mm)
10 to 30
20 to 55
85 to 100
No. 8 (2.36 mm)
0 to 10
5 to 30
10 to 40
No. 16 (1.16 mm)
0 to 5
0 to 10
No. 50 (0.30 mm)
0 to 5
Bedding & Jointing
Jointing
Jointing only
only
Washed material: percent passing No. 200 (0.075 mm) sieve < 2%
Placing Bedding Material
Must be clean!
Place 2 in. (50 mm) thick rails on compacted No. 57
Adjust elevations as needed
Set & adjust screed bucket
Laser guided screed – no rails used
Dump & spread bedding material
Distribute stone & screed
Manual/mechanical installation differences
Hand screed for residential &
small commercial projects
Bedding layer touch-up
Removing screed rails as paving progresses
Fill rail imprint with stone
Covered catch basin
Powered screeding
Powered screeding with asphalt spreader
Edge pavers
cut and
placed,
then
compacted
Compaction before filling
openings
Compact before sweeping in aggregate
Filling the openings with No. 8
stone, final compaction
Excess stones removed,
then final compaction
Keeping sediment
away from
the pavers
PICP Design Basics: Exfiltration Options
• Full Exfiltration
• Partial Exfiltration
• No Exfiltration
PICP Design Basics: Exfiltration Options
Full Exfiltration
Sandy soils (> 0.5 in/hr)
No perforated drain pipes
PICP Design Basics: Exfiltration Options
Partial Exfiltration – detention & exfiltration
Silt/some clays
Perforated pipes at
bottom of base
PICP Design Basics: Exfiltration Options
No Exfiltration – detention only
High rock,
High water table,
poor soils
Observation well:
• Install at lowest point of pavement
• Min. 6 in. dia. perf. pipe w/cap
• Monitor drainage rate, sediment, water
quality, temperature
Maintenance
Annually: overall system performance inspection,
check observation well , inspect after major
storm, vacuum surface (once, twice, or more)
to ensure optimum design life performance
Maintenance checklist (specific to each project)
Model maintenance agreement
Monitor adjacent uses
Structural
Loads
& PICP
courtesy of ICPI
Thank you!
Rick Crooks
Mutual Materials
Company
(425) 922-7370
[email protected]