Handbook for Pervious Concrete Certification in Greater Kansas City
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Handbook for
Pervious Concrete Certification
in Greater Kansas City
This support material is part of the CPG Pervious Concrete Certification Program
1
Table of Contents
Preface: The CPG Pervious Certification Program
1. Pervious Concrete: What’s it all about? (Overview)
2. Brief History of Pervious Concrete
3. Design Elements for Pervious Concrete
Hydrology, Drainage, Layout, Subgrade Soil, Subbase, Thickness, Jointing
4. Basic Mix Design Information for Pervious Concrete
Aggregates, Cement & SCM’s, Water, Admixtures, Proportioning
5. Testing Pervious Concrete
6. Pervious Pavement Construction
Equipment and Tools
Test Panel Placement and Approval
Pre‐Construction Meeting
Excavation, Filter Fabric, Subgrade, Base, Jointing, Curing,
Hot & Cold Weather Practices
7. Maintenance
8. LEED® Credits
9. Decorative Pervious
10. Specifiers Guide for Pervious Concrete for Stormwater Mitigation in Greater
Kansas City & Pervious Construction Checklist, Pre‐Construction Checklist
11. Websites & Resources
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Preface
CPG Pervious Certification Program
4 Levels CPG Pervious Concrete Certification
Level 1: CPG Pervious Concrete Technician (Required for Contractors & Ready Mix Producers, optional and
recommended for inspectors, designers, stormwater engineers, architects, civil engineers)
Requirements:
A) Pass the CPG Pervious Concrete Written Exam with a score of 80% or higher
B) Complete the Performance Evaluation usually done the same day as the written exam, demonstrating
subgrade prep, form placement, the proper use of tools, placement procedure, proper jointing, proper curing,
etc.
C) Pass an individual Performance Evaluation on the individual’s 1st job or test site, set up by the individual.
D) Valid for 5 years after receiving the certification.
E) Re-certification is required within 90 days after the expiration date listed on the wallet card/certification
certificate.
F) Starting January 1, 2012, re-certification applications require 2 hours of continuing education credits on
pervious concrete. These hours can be local, regional or national seminars, demo’s or workshops on pervious
concrete. It is up to the individual to keep records of these continuing education hours to turn in with the re-
certification application.
Level 2: CPG Pervious Concrete Installer (Upgrade option for Contractors)
Requirements:
A) Have a current ACI Flatwork Finisher Technician Certificate.
B) Have a current CPG Level 1 Pervious Concrete Technician Certificate.
C) Project Experience with successful pervious construction in a minimum of 3 projects, with a total area
exceeding 10,000 sq. ft.
Level 3 CPG Pervious Concrete Craftsman (Upgrade option for Contractors)
Requirements:
A) Have a current ACI Flatwork Finisher Technician Certificate
B) Have a current CPG Level 1 Pervious Concrete Technician Certificate
C) Have a CPG Level 2 Concrete Installer Certification.
D) Document work experience constructing pervious pavements exceeding 1,500 hours (not including the 10,000
sq. ft. needed to qualify for the Installer)
Level 4 CPG Advanced Pervious Concrete Team Certification
(Optional for Contractor and Ready Mix Team)
Well above and beyond traditional concrete, successful pervious concrete placements require a dedicated team
with an excellent relationship between the Ready Mixed Concrete Producer and the Concrete Contractor. The
Concrete Promotional Group has assembled an advanced mixture design and construction review for
contractor/producer teams looking to advance their pervious concrete construction knowledge. Certification will
encompass one producer, one contractor, one pervious concrete mixture, and one placement technique. Upon
completion of the process the producer will be provided with a performance and testing certification for the final
mixture design. The contractor will be provided with certification of the in-place mixture properties and
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performance. By completing the certification process a pervious concrete team will have documentation showing
the unit weight, strength, and infiltration that will be achieved.
Requirements:
A) Have a current ACI Flatwork Finisher Technician Certificate
B) Have a current CPG Level 1 Pervious Concrete Technician Certificate
C) Complete the Team Review Process outlined below:
Outline of the Review Process:
The certification process involves an interactive ½ day series of two test placements (at a location of the team’s selection).
A. Starting mixture provided by producer. The mix is proprietary so it is kept confidential. Only the ready mix
producer and Dr. John Kevern will discuss these details.
B. Contractor will place a 4 cy sample panel. Concrete will be held 45 minutes after batching to simulate field
conditions. Inverse slump, ASTM C1688 unit weight, and timed discharge values will be recorded.
C. The contractor, producer, and CPG representative will discuss consistency, workability, finishability, and
discharge capacity. The mixture will then be modified to better meet the desired criteria.
D. The contractor will then place a second 4 cy sample panel using the modified mixture. Inverse slump, ASTM
C1688 unit weight, predicted unit weight, and timed discharge will be measured on the fresh concrete. Cylinders
will be created for the compaction density curves for reporting voids, unit weight, permeability, 7 day
compressive strength, and 28 day compressive strength for the selected mixture.
E. The contractor and/or producer is responsible for obtaining at least (3) 4” diameter cores for hardened unit weight
and permeability testing at UMKC.
F. Field infiltration will be performed according to ASTM C1701 on at least five (5) locations.
G. The performance and testing data will be used to create mixture certification documentation and individual field
evaluation documentation.
Deliverables:
Deliverables will include a description and summary of the certification process including all testing data for reproduction
and transmittal to any interested party.
All certified individuals and companies can be found listed on the CPG Website at www.concretepromotion.com .
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Chapter 1
Pervious Concrete: What’s it all about?
What is Pervious Concrete?
Pervious Concrete is a specialty concrete used to allow water to intentionally pass through the surface of a pavement and
allow stormwater to eventually absorb back into the surrounding soils or evaporate. This keeps runoff water from
downstream urban flooding and erosion. It also breaks the cycle of water treatment plants needing to treat stormwater
where municipalities have combined sewer and stormwater systems. Pervious concrete pavements are “best management
practices” (BMP’s) to collect, clean and cool stormwater. This usually eliminates the need for detention/retention ponds, thus
reducing construction expenses, safety issues, and maintenance costs.
Why are we worried about Stormwater? The EPA NPDES Phase II requirements now mandate municipalities to implement
stormwater mitigation policies. New developments, both residential and commercial, must show how stormwater leaving the
property will not exceed predevelopment conditions. That includes both quantity and quality of stormwater. There are many
types of stormwater mitigation techniques. Pervious concrete is one of many options available.
Why choose Pervious Concrete over other BMP Methods? Pervious Concrete not only collects stormwater but it also filters
and cools it economically with local materials. Low Impact Developments (LIDs) are encouraged to save space, save natural
resources and promote sustainable communities. What does this mean? Developments are encouraged to build up rather
than out. With a pervious concrete parking lot or pavement the detention pond could be eliminated completely, thus
conserving green space.
Figure 1.1
Pre Development Post Development Low Impact Development
What about freeze/thaw concerns and clay soils in Kansas City Metro Area? Pervious Concrete is usually more freeze/thaw
durable than “conventional” concrete. Pervious concrete pavements have not been lost to freeze/thaw conditions. The voids
in the pervious concrete allow for water (which expands 9% when it turns into ice) to expand and contract within the voids
which keep it from breaking up the pavement. Pervious concrete in clay soil markets becomes a “system”. It is designed with
a rock base under the previous layer to temporarily hold stormwater since the clay soils prevent fast recharging of the subsoil.
Pervious concrete pavements typically loose ¾ of an inch to an inch of water a day to evaporation. A three inch rain would be
gone in 4 days just to evaporation. The clay soils usually allow a slow exfiltration rate of .5 to .05 in the market.
5
Pervious
Rock storage
Filter fabric
Ground soils
Figure 1.2
How does Pervious Concrete fit in with Sustainability & Green Building Ideas?
Pervious Concrete Pavements:
Maximize Open Space (LEED SS 5.2), the temporary detention area is under the pavement rather than beside it,
taking the system vertical rather than horizontal.
Stormwater Quantity Control (LEED SS 6.1), pervious concrete can intake huge amounts of stormwater.
Stormwater Design‐Quality Control (LEED SS 6.2), filters the stormwater & cleans it.
Heat Island Effect (reduction) Non‐roof (LEED SS 7.1), improved solar reflective index (SRI) reflects the suns’ light
rather than absorb it like dark or black pavements.
Construction Waste Management (LEED MR 2), concrete is ordered as needed and can be recycled.
Recycled Content (LEED MR 4), there is pre‐consumer recycled content in the concrete mix.
Regional Materials (LEED MR 5), pervious concrete is delivered with local materials from a local company, typically
within 20 miles of the jobsite.
Water Efficient Landscaping (LEED WE 1), Eliminates using surface or subsurface water for irrigation, instead
capturing rainwater or brown water for landscaping. Pervious can catch & contain rainwater and recycled for
landscaping use.
Water Use Reduction (LEED WE 2), the intent is to lessen the burden on municipalities for water supply and
wastewater. Pervious pavements can capture stormwater divert the water to cisterns, for brown water use, in
flushing toilets and watering landscaping.
More detailed information on Pervious Concrete’s role in qualifying for Leadership in Energy and Environmental Design (LEED)
for Sustainable Building and Communities is available from CPG. See our website at www.concretepromotion.com and look
under the pervious tab on the left side of the front page.
What maintenance is needed? An occasional vacuuming or wet/vac is usually sufficient, as dirt, leaves, or fines typically sit in
the top inch under the surface. More maintenance information can also be found at www.concretepromotion.com .
The Concrete Promotional Group, 913‐341‐5800, 10707 Barkley, Suite A, Overland Park, KS
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Chapter 2
Brief History of Pervious Concrete
Pervious Concrete has been around for hundreds of years. The Europeans recognized the insulating properties in structural
pervious concrete for their buildings. Europeans have also used pervious concrete for paving including on the Autobahn. Stories
passed down through the years tell us that our soldiers didn’t mind walking on pervious roads during World War II because it meant
their feet would be dry!
Pervious was brought to the United States after World War II. It first showed up in Florida and other southern coastal states.
Slowly it has migrated to the other states where it has met different successes. As with any new product, it has had to prove itself.
Many well intended ready mix producers have produced the product and many well intended contractors have placed the product.
Some did well, others did not. As it is true with any material and construction technique, there is a science to it and a best way to
conduct the construction. Education and experience are the key to success. The coastal states have experienced pervious concrete
for over 20 years. The hesitation to move into the Midwest and Northern States was mainly due to freeze/thaw concerns. Now that
those concerns are no longer considered a problem, the product has moved quickly across the United States.
In the 1990’s the U.S. Environmental Protection Administration (EPA) came out with the Clean Water Act (CWA), that later led to
other phases of implementation to preserve the waterways from stormwater borne pollutants. EPA identifies “stormwater runoff is
generated when precipitation from rain and snowmelt events flow over land or impervious surfaces and does not percolate into the
ground. As the runoff flows over the land or impervious surfaces (paved streets, parking lots, and building rooftops), it accumulates
debris, chemicals, sediment or other pollutants that could adversely affect water quality if the runoff is discharged untreated. The
primary method to control stormwater discharges is the use of best management practices (BMPs).” (EPA.gov). Pervious concrete is
one of many BMP’s recognized by the EPA as well as our local American Public Works Association (APWA) and the Mid America
Regional Council (MARC). The local APWA/MARC Best Management Practices for Stormwater Mitigation Manual can be found at:
http://www.marc.org/Environment/Water/bmp_manual.htm . Basically, it requires the developer/owner to keep as much
stormwater on property as possible. If stormwater leaves the property it must leave cleaner and cooler than before. Pervious
concrete allows for the filtering/cleaning and detainment of stormwater.
Since the municipalities have been required to enforce stormwater mitigation with the implementation of EPA NPDES Phase II,
many BMP’s have been placed and tested to find out which one is going to work for their area. Balancing BMP’s becomes an art of
balancing placement costs, maintenance costs, aesthetics and functionality. Budgets are tight and skepticism is high, because the
BMP’s are relatively new concepts and some unproven.
The first pervious placement in the Kansas City Metro Area was in Sugar Creek, MO in November 2005. Since that time about 30+
pavements have been placed and many lessons learned about what makes pervious concrete “good”. Herein, are the current
guidelines that have been learned and adjusted. There are some basics we know about placing a successful pervious pavement:
1) The design of the pervious pavement has a hand in its success.
2) The mix design delivered by the ready mix producer has a hand in its success.
3) The contractor placing the pervious concrete has a hand in its success.
4) The owner has a responsibility for proper maintenance to keep the system functional.
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Chapter 3
Design Elements for Pervious Concrete
Hydrology
The reason pervious concrete is being considered in the first place is because of water. Stormwater runoff is a negative issue
affecting the quality of our urban and suburban areas, chasing pollutants down into the typically combined stormwater/sewer
systems. This ends up doing three things, 1) sending rainwater to the water treatment plants for cleaning then back out to public as
fresh cleaned water. 2) Sending rainwater into the streams, creeks and waterways creating urban flooding. 3) Sending polluted
rainwater into the waterways altering the balance of nature hurting native plants and wildlife. (In Kansas City we’ve seen the latter
two points in Indian Creek, Brush Creek, Tomahawk Creek and the Little Blue River.) We are all spending millions of dollars
nationally cleaning rainwater in our water treatments plants, which is really unnecessary.
Most municipalities identify a typical rain event they require to be mitigated on developments. Nationally the most common rain
event required to be mitigated is a 25 year storm event in 24 hours. The numbers vary by geographic area depending on the kind of
rain events that frequent that area and the type of soils in the area. Obviously sandy soils let water percolate back into the
surrounding soils faster than fat clay soils will. In the Greater Kansas City Area’s APWA/MARC Stormwater Best Management
Practices Manual, the 100 year rain event in 24 hours is required to be mitigated. Depending on which part of town you are in, the
number is somewhere between 8 or 9 inches of rain in 24 hours. Our local area has a majority of clay soils/expansive clay soils. Rain
water will not percolate through the clay quickly, it seeps slowly. Regulations allow some water to run off site, but that water must
be cleaner and cooler than when it hit the site. In other words it needs to be filtered or cleaned.
The Portland Cement Association (PCA), the National Ready Mixed Concrete Association (NRMCA) and the American Concrete
Pavement Association (ACPA) have jointly produced CD #063.02, Pervious Concrete Hydrological Design & Resources, 2007 Edition,
as a resource. It can be used as an aid in designing the thickness of pervious pavement systems depending on the hydrological
needs. This CD is extremely easy to use and recommended for anyone designing pervious pavements. It provides the capabilities of
printing several helpful charts and graphs.
In the Greater Kansas City Area the APWA/MARC BMP Manual requires a minimum of a 12” clean rock base beneath the porous
pavement whether it be porous asphalt, porous pavers or pervious concrete. Sidewalks are not held to the same standards, there is
no minimum listed for sidewalk applications.
Basically the hydrological calculations that need to be established are: 1) How much water needs to be mitigated (check
municipal requirements)? 2) How much water will 12” of clean rock base hold (typically 40% voids)? 3) Is more base rock needed or
will the 12” hold it satisfactorily? 4) Adjust as needed. Do not calculate the pervious concrete to hold any of the stormwater. That
way you will not have water standing on the surface, thus protecting it even more from freeze/thaw expansion. Extra base may be
needed if roof top guttering runs into the pavement or adjacent areas drain into the pervious area.
Are overflow piping or additional water storage containers needed? If your water calculations are correct you likely will not need
additional means. However, depending on the amount of water you are mitigating you may want to allow for an overflow. See
figure 3.1 for an example. Overflow pipe may be placed at the top of the clean rock base. This pipe can be routed to another BMP
such as a bioswale or to the storm/sewer system with a delayed and controlled release. Some sustainable projects have used a
sump pump to reuse this “brownwater” indoor to flush toilets and outdoors for watering landscaping.
8
Pervious Concrete
Overflow Pipe
Clean Rock Base
Figure 3.1
NOTE ‐ approximately ¾” to an 1” of water will evaporate a day. This has been proven on a national level and on a local level in
Leawood, KS in I’Lan Park. So even in the worst clay soils possible, the water does eventually go somewhere. After a two inch rain,
the rainwater can be expected to be gone in about 2‐3 days.
Why would a designer or owner choose pervious concrete pavements instead of other acceptable BMP’s? First off what are the
other types of acceptable BMP’s and what are their limitations?
Rain Gardens (for smaller areas, more residential, needs a lot of maintenance, pulling weeds, etc.)
Figure 3.2
Rain garden Bioswale
Bio‐Swales (for larger areas, can look like weeds‐gone‐wild, until the public is educated on the application)
Detention Ponds (most commonly used BMP, needs land, standing water for mosquitoes, safety hazard for children, needs
maintenance, costly to place in the first place)
Figure 3.3
Fenced wet detention pond Lake Lenexa, dam and spillway
Ponds or small lakes turned into recreational areas as in Lenexa, KS (a huge investment of land and money from the
municipality, would need to be turned into a Parks & Rec. main line budget item)
Many different types of proprietary systems which can include special tree/plant wells at street side or cisterns or piping
below the surface (fairly costly to construct and purchase)
9
Figure 3.4
Proprietary plant wells system Porous asphalt
Porous Asphalt (At the time of publication, there are 2 in the Greater KC Area, one in a park in Lenexa, KS the other in a
church parking lot in southern KCMO. This is an oil based material. Do you really want your water running through this
picking up hydro‐carbons and depositing them back into the ground sources? The first one in Lenexa, KS has issues of not
passing water through the surface. Some in other markets have “birdbaths” with tire imprints where cars park.)
Porous Pavers (This is typically a 6 to 8 step installation process, building the base with rock, sand, etc. Maintenance is
much higher on this type of paving material choice; it is more labor intensive and takes more time to place than the other
two paving options.)
Figure 3.5
Various systems Porous pavers Grasscrete
Grasscrete proprietary systems combine some kind of structure below the surface to hold aggregates and soil mediums for
hearty grasses or plants. (These systems take a while for the plants to establish and are multi‐step construction processes
to place, and can take a lot of maintenance.)
Pervious Concrete (see below)
Figure 3.6
Grounds Park parking lot expansion Thermo Fisher Scientific parking lot expansion
Blue Springs, MO Lenexa, KS
So why choose pervious concrete parking lots to solve your stormwater mitigation issue?
It helps in achieving “Low Impact Developments” (LIDS), in other words building UP, instead of OUT. By placing pervious
concrete the temporary detention basin (the clean rock base) is UNDER the parking lot surface. It eliminates the need for
additional land to place a detention pond next to the building or parking lot. The pervious parking lot becomes both the
detention pond and the parking surface in one. Build up not out. The owners save on land cost too, as they don’t need
additional land for the detention pond.
Pervious concrete is green or sustainable. Pervious concrete is placed with regionally available materials (anything within
500 miles of a jobsite to cut down on energy for transportation costs).
Pervious concrete is recyclable. If for some reason it needs to be replaced someday in the future, it can be used for base
rock or possibly for aggregate in concrete.
10 Pervious can have recycled pre‐consumer materials in it. The slag or fly ash found in the KC market is often in the concrete
mix. By using these beneficial supplementary cementitious materials in concrete they help keep them out of landfills.
Pervious concrete is low maintenance. An occasional vacuuming or wet/vac will pull dirt, sand and debris from the surface.
Pervious concrete like regular concrete is light reflective (especially when slag is in the mix) and cooler. This helps fight the
Urban Heat Island Effect. Cooler pavements mean cooler environments near buildings and homes, and this means lower air
conditioning bills in the summer. Research shows that by building with light reflective and heat reflective materials for
roofs and pavements, and increasing green space (trees and plants) the ambient temperatures in urban areas can be
reduced 5°F or save up to 18% on air conditioning bills.
Figure 3.7
Asphalt pavement at night, Concrete pavement at night,
very little light reflectance much more light reflective
The water collected within the pervious pavement system can be collected and rerouted (sump pump or other means) to
use for irrigating landscaping or for flushing toilets in nearby buildings. This lessens the burden on municipal water supply
and lowers the need for wastewater systems.
Figure 3.8
Finley Stadium, Chattanooga, TN, built in 1997, partial pervious pavement, collects stormwater,
recycles the water to water landscaping around the stadium and the football field
Impervious pavements near or next to trees and bushes drain water away from trees. Everyone has seen concrete
sidewalks “tenting”. Tree roots drive upward to find air and water for nourishment. Pervious concrete allows water and air
get to the tree roots. No more sidewalk tenting.
Design & Layout
Lessons learned in design and layout to maximize pervious success in regards to permeability and durability:
111. The bottom of the clean rock base should be as flat as possible. Gravity will feed water to the lowest point. If the
pavement is on a slight grade make up the difference from bottom to the grade on the surface, with the clean rock base as
it is less costly than the pervious concrete.
Figure 3.9
2. Use trenches or check dams or other means in stabilizing downhill water flow when building on a grade.
Figure 3.10
3. Use a dual concrete design for maximum durability. Pave the drive lanes in regular concrete (where there are more turning
movements) and pave the parking stalls in pervious concrete. Place the base clean rock under all of it. Make sure both the
regular concrete and the pervious pavement are the same thickness for construction ease. This way the base under the
entire parking lot is used efficiently for temporary storage, while utilizing regular concrete where the most traffic and stress
occurs on the surface.
Figure 3.11
Dual concrete design with pervious and conventional concrete
124. Pay special attention to the outer edge of the pavement where pervious meets landscaping or grass. Also in the middle of
the parking area where trees and landscaping islands are within the pervious surface. This is where the maximum exposure
to soils occurs. Rains will wash soils, landscaping mulch, etc. into the pervious pavement. Make sure plans are in place to
immediately mitigate the surrounding soils with sod (or equal) to keep dirt and mulch in place and out of the pervious
pavement. The pictures in Figure 3.12 show soils and mulch carried into pervious pavements after rains. The exposed soils
and mulch were not satisfactorily secured. Landscaping islands should be slightly depressed behind the curb. Erosion
control needs to be in place until grass or landscaping plants are mature. This is also the reason why pervious is used for
parking lots more often than sidewalks/paths. Sidewalks have so much more linear exposure to the dirt/grass. Parking
areas can limit the exposure to soils to the outer perimeter.
Figure 3.12
5. When using green practices in design it is customary to place trees and shrubs within the parking lot matrix to provide
shade and evapo‐transpiration. However, for pervious parking lots, it is best to limit the trees to the outer perimeter of the
parking area, where they are more easily maintained, and the dirt/mulch doesn’t contaminate the pervious surface within
the parking area as in the picture in figure 3.12.
Subgrade
The existing subgrade under the stormwater detention area shall not be compacted or subject to excessive construction
equipment traffic prior to coarse aggregate bed placement. The subgrade may be scarified to improve infiltration rates.
Cuts necessary to establish proper subgrade level shall not be compacted or subject to excessive construction equipment
traffic prior to coarse aggregate bed placement and may be scarified to improve infiltration rates.
When fill is needed to meet proper subgrade level, some compaction may be necessary. Compaction to approximately 92%
proctor is sufficient.
Base
Filter fabric, 4 oz non‐woven geotextile shall be placed on the subgrade/soil prior to placing the base material.
The filter fabric will continue up the sides to the surface to keep fines from migrating into the storage layer.
It is advisable to continue the filter fabric up and over the surrounding soils approximately 2 to 3 feet. This will “hold” the
soils under the fabric acting as erosion control until the project is complete and landscaping is ready to secure the soils next
to the pervious pavement. This is an optional solution to erosion control. When the soils are secured the filter fabric can
be cut to the edge of the pervious pavement. See figure 3.13.
13Figure 3.13
The coarse aggregate for the base or “storage” layer shall be a minimum of 12” in the Greater Kansas City Area.
(APWA/MARC Stormwater BMP Manual) This has been established to mitigate the 100 year rain event in 24 hours. A true
stormwater evaluation may be required for the specific site by a qualified stormwater engineer to meet municipal
requirements. The base thickness for a parking lot can vary depending on the hydrological calculations, discussed in the
beginning of Chapter 3.
Sidewalks are not held to the same standard. Sidewalks tend to have 4 to 6” of clean rock base.
The material for the base shall conform to ASTM C33 standards and be capable of having minimum voids of 38% by weight
measured in accordance with ASTM C29. It shall be clean washed rock with less than 2% retained on the 100 sieve. The
rock shall be a maximum top size of 1 ½”. (Fines plug the system.)
The material shall be placed in 6 inch lifts and lightly compacted with equipment. Keep movement over the storage bed as
minimal as possible. Install to the required grades.
Place hay bales or equivalent at the toe of slopes to prevent sediment from washing into beds during site development.
The base shall be moist at the time of pervious concrete placement to ensure no water from the pervious is drawn down
into the base layer. A water source should be at the job site to spray the base immediately prior to pervious placement.
The base may have a component installed to allow for moving the collected rainwater to be used for irrigation or for
brownwater use in nearby buildings.
The base material for pervious pavement is a function of the stormwater detention, not structural performance. In some
areas of the country no base material is needed as the soil conditions allow water to migrate through in a timely manner.
In the Kansas City market we’ve already established the minimum standards require at least 12” of clean rock for
stormwater temporary detention.
Pervious Thickness
Experience has been the driving force in making decisions determining the thickness for pervious pavements. 6 inches is
common for parking areas for automobile traffic and an occasional truck. 8 inches is used for residential streets and more
trafficked drive lanes in parking lots. Refer to ACI 330R Guide for the Design and Construction of Concrete Parking Lots for
suggestions when designing concrete parking areas. Keep in mind pervious is not meant for heavy 18 wheeler truck traffic
at this time.
The thickness of the pervious layer is somewhat determined by the equipment used to place the concrete. The roller
screed tends to be the most commonly used screed in the Kansas City area. Consolidation by this equipment doesn’t reach
further than 6 to 8 inches down into the concrete.
14Figure 3.14
Side view of pervious concrete thickness Cutting a joint along a string line Cutting a joint in fresh pervious concrete
Jointing
Jointing pervious concrete should be treated much like conventional concrete. Use the same rules of thumb.
Take the thickness of the pavement multiply it by 2 to reach the maximum spacing in feet. Ex. 6” X 2 = 12’ spacing. For
pavements thicker than 7 inches, the maximum joint spacing is 15’.
Isolation joints shall be used when abutting fixed structural structures such as columns, manholes, signposts, light poles,
buildings etc.
Construction joints may be needed at the end of the day’s paving, or when there is a prolonged delay in the next concrete
truck delivery.
Saws should not be used for jointing. The problem using saws for jointing is that saws would require uncovering the curing
pavement, exposing the fresh concrete to wind, sun and heat. Early entry saws are out of the question completely, as the
pavement has been put to “sleep” with the hydration stabilizer. Again the pavement would be uncovered too long during
the sawing process. Regular concrete saws would adequately cut the pavement; however, waiting to saw after the
pavement has cured properly for 7 days would be fruitless. The pavement would have already cracked by the 7th day.
Sawing prior to the 7 days again, leaves the pavement open to moisture loss and possible raveling at the surface. The slurry
from sawing is problematic, as it could clog part of the system. Saw cuts are being done in other markets. It is possible that
saw cuts could be entertained in this market if the curing element could be conducted satisfactorily. Contractor would
submit a plan to the owner/designer for approval to use saw cuts, and implement the plan into the Test Panel Placement
for acceptance. (See test panel placement in Chapter 6, Pervious Construction.)
15Chapter 4
Basic Mix Design Information for Pervious Concrete
Cement & Cementitious Materials
Portland Cement Type I, II or I/II is readily available in the Kansas City market and used for pervious concrete production.
(ASTM C150)
Slag Cement (Ground Granulated Blast‐Furnace Slag, aka. GGBFS) is a cementitious material available in the market and
used in pervious concrete production. (ASTM C989)
Fly Ash Type C and Type F are both available in the market and used in pervious concrete production. (ASTM C618)
Slag and fly ash are supplementary cementitious materials often used to replace the amount of cement. Both products are
industrial byproducts. Using them in concrete keeps them out of landfills helping to green our environment. They both
offer good benefits to concrete and they offer strength gain. Which means they add durability in the long run. Both require
longer curing times for the concrete to initially set and gain strength.
Aggregates
Aggregates can have a direct influence in the permeability, surface texture and the appearance of the pervious slab.
A uniform large aggregate size is preferable for maximum permeability. This is opposite of the optimized gradation usually
wanted in a regular concrete mix.
Aggregates large and small shall conform to ASTM D448 and comply with ASTM C33.
The size of the large aggregate will have an effect on aesthetics and the top size of the “holes” in the surface.
¼” to ½” large aggregates are preferred. Most of the aggregates used in the Kansas City market have been 3/8” or 1/2”.
The specific gravity shall be >2.5 and the absorption shall bepervious must be placed in cold weather, use water diverted from the “hot water” system that is measured accurately.
Otherwise, wait until the ambient temperatures have warmed up.
Figure 4.1
Keeping aggregates wet and cool in the hot summer
Admixtures
Air entraining admixtures shall conform to ASTM C260. Dose as per the manufacturer recommendation for conventional
concrete in severe freeze/thaw conditions. Dosages usually start at 2 oz/cwt
NOTE – there is not an ASTM test method for testing air in pervious concrete. The convention test for concrete would not
be able to differiate between the voids in the matrix or the air entrainment.
Water reducing admixtures shall conform to ASTM C494, type A, B D or F. Dosages for pervious concrete can exceed the
ranges typically used for conventional concrete. Experience is the best teacher. A starting dosage rate of 6 oz/cwt is
recommended.
NOTE – The polycarboxylate type of water reducers have been proven to work best for pervious concrete mix designs. They
are sometimes more costly than other types of water reducers, which is why some ready mix producers avoid them when
designing their mix designs. Results have shown that polycarboxylates make significant strides in the discharge and
placement process to make it worth the extra cost! Don’t under estimate the long term savings in using the slightly more
expensive product.
Hydration stabilizers also known as extended control admixtures, shall conform to ASTM C494, type B or D. This admixture
is critical to the success of the mix.
Examples of hydration stabilizers are BASF/Delvo® or Grace/Recover®; all pervious mix design shall have these products or
another equal product.
Hydration stabilizers and/or water reducers shall be available on the jobsite for re‐dosing as needed. Placing pervious in
hot temperatures often requires more hydration stabilizers, which include the ability to re‐dose on the jobsite.
Viscosity modifying admixtures (VMA’s) have been used successfully in other markets. They have met limited to poor
success so far in the Kansas City area. One opinion is because viscosity modifying admixtures may need more mix water to
get them properly dispersed throughout the mix. Pervious concrete is typically designed with a .30 w/c ratio, such little
water may be limiting the ability for the admixture to”work” properly. VMA’s can make the mix “gummy” or “sticky”.
VMA’s are commonly used in self consolidating concrete mixes.
New admixtures for pervious are appearing every day. Recently admixture companies have bundled together water
reducers, hydration stabilizers and viscosity modifying admixtures in one product to market for pervious mixes. These have
been met with mixed reviews. Be aware and open to trying new products as the technology and education changes for
pervious.
It is recommended to use fibers polypropylene or cellulose, < 1.5 in. fibrillated or micro fiber type. Fibers have been
included in all locally placed pervious projects. Other markets have used macro fibers in pervious concrete also. More
research needs to be done to discover the advantages and disadvantages of these fibers.
Fiber dosage shall be a minimum 1.5 lbs/yd.
Fibers are suggested to be removed from their bags and distributed in 2‐3 gallons of water before addition to the mix to
prevent balling materials and promoting even distribution.
17 NOTE – Fiber benefits include preventing excess raveling, preventing too dry of a mix and preventing over compaction from
too wet mix.
Proportioning Pervious Concrete Mixes
The mix design shall be submitted to the designer/owner for review and approval. Proportions shall be in compliance with
ASTM C1688. Trial mixtures must be tested to establish proper proportions and determine expected behavior.
Concrete ready mix producers may have mixture proportions optimized for performance with local materials.
The pervious concrete mixture void content should range between 15 to 25% per ASTM 1701 or the new ASTM standard
coming out spring 2011 for measuring voids in the hardened state.
The water/cement ratio shall be between .30 and .34.
Supplementary cementitious materials (SCM’s), either fly ash or slag shall not constitute more than 25% of the cement
replacement individually. If used in ternary blended cement, the SCM’s shall not exceed 50% of the mass of the Portland
cement.
Yield, Density and Permeability
In conventional concrete, yield is closely related to the volume of concrete placed, as established in ASTM C94. Pervious
concrete is different; the volume of concrete placed can vary depending on the level of compaction during placement.
Also note that the density (unit weight) for pervious concrete varies from the density measured in accordance with ASTM
C1688 and the density of the hardened pervious concrete. So the contractor ordering the pervious concrete will need to
order with care as pervious will vary more than conventional concrete.
Density of the installed pervious concrete affects the voids in the hardened state, thus affecting the permeability of the
final in‐place product.
Density is also affected by the properties of the materials in the pervious mix design (aggregates, cement, water,
admixtures etc.)
Infiltration of water through the voids in the hardened pervious pavement can be field tested by using ASTM C1701.
Helpful Information for the Ready Mix Producer
The average truck load of pervious concrete is 6 yards. Pervious is much harder to get out of the truck as it ages in the truck
because the admixtures have been used up and lost their effectiveness. 10 yards loads will likely need to be re‐dosed on
site with additional water reducers and/or more hydration stabilizers. It is much easier to dose at the plant than it is to try
and guess how much concrete is in the truck half way through unloading the truck. Plus it means stopping discharge and
stopping the crew while the “fix” is being conducted on site. Experience has taught us shorter loads at 6 yards saves
everyone time and money in the long run, than a 10 yard load.
The ready mix truck must have good quality “paving fins” to discharge from the truck properly. Older trucks with the fins
worn down or trucks with no paving fins can jeopardize getting the concrete out of the truck. These trucks have slowed
down jobs significantly, turning a 15 minute discharge into a one hour discharge! We’ve established that pervious is very
perishable. Taking a long time to get the mix out of the truck jeopardizes the entire load.
Every delivery of pervious should have the water reducer and/or the hydration stabilizer available at the jobsite for re‐
dosing as needed. Review the Admixture section above for more details about the admixtures.
The truck drivers need to be educated about pervious, what is it, how it looks, etc. Jobsites have had drivers jump out of
the truck and add 20+ gallons trying to “fix” the load because they didn’t know what is was. Truck drivers should be trained
on the restrictions pertaining to addition of water at the jobsite for pervious and re‐dosing admixtures in the field.
Ambient temperatures affect pervious concrete even more that conventional concrete (because it is at a lower water
cement ratio).
18 Aggregate stock piles need to be kept at the target SSD. Moisture in aggregates has a HUGE affect on the mix design. It is
more noticeable in pervious concrete than with conventional concrete. Moisture readings may need to be set to zero
manually to get the appropriate water in the mix. This depends on the quality control at the plant, moisture probe
calibrations, etc.
Spacing the trucks to the jobsite can be tricky until the crew establishes a jobsite rhythm (usually after the 2nd truck). Send
the first truck, wait 30 minutes, and then send the rest every 15 ‐20 minutes depending on the feedback from the field.
Avoid stacking the trucks at the jobsite, as pervious is more perishable than conventional concrete.
It is possible to unload two trucks at a time into a conveyor belt hopper, IF the contractor can adequately keep up with the
placement at the other end.
The mix design should be submitted for approval to the contractor and designer.
It is advisable to place many trial batches and test panels to adjust the plant mix design for pervious. This is under utilized
by many ready mix producers.
Ready mix quality control technicians and sales personnel should all be versed in ASTM 1688, ASTM 1701, the Inverted
Slump Test and any new ASTM tests that are published for pervious concrete.
19Chapter 5
Testing Pervious Concrete
There are currently 2 ASTM tests designated specifically for pervious concrete (as of April 2011). ASTM C1688, Standard
Test Method for Density and Void Content of Freshly Mixed Pervious Concrete and ASTM C1701, Standard Test Method for
Infiltration Rate of In Place Pervious Concrete
Spring 2011 a new standard will be released to measure the voids in the hardened pervious concrete. As soon as it is
released this document will be updates with the information.
ASTM and ACI are working in tandem to develop standardized tests for other pervious concrete attributes, such as flexural
and compressive strengths, abrasion resistance, etc. Pervious is still relatively new so it will take some time for the
standards to be developed and published.
NOTE – The ASTM Standards for conventional concrete that we are accustomed to using for flexural and compressive
strengths DO NOT apply to pervious concrete.
ASTM C1688, Standard Test Method for Density and Void Content of Freshly Mixed Pervious Concrete
Figure 5.1
ASTM C1688 Equipment & materials needed A proctor hammer First lift compacted
Second lift compacted Striking off the surface Weighing & final calculations
ASTM C1701, Standard Test Method for Infiltration Rate of In Place Pervious Concrete
Figure 5.2
ASTM C1701 Equipment & Materials Needed Calibrated markings in the rim Secure the rim with putty
201 gallon of water into apparatus (Step 2 if needed) 5 gallons into apparatus Final calculations
The Inverted Slump Cone Test
Inverted Slump Test
Picture credit: Kevern, Schaefer, Wang
Figure 5.3
Filling the inverted slump cone Checking workability Workable mix Over‐worked mix
Using ASTM 1688 and the Inverted Slump Concrete Test for jobsite acceptance:
The workability and consistency of pervious concrete may be determined for each ready mixed truck to ensure quality
construction. Typically workability is adjusted on‐site for the first load and then readjusted during batching for all
subsequent loads.
a) Check Batch Ticket: Upon arrival at the jobsite. Check for the correct mixture and appropriate delivery and mixing
time.
b) Check Workability: Perform an inverse slump check. If workability remediation is required first add 0.5 to 1.0 gallons
of water per cubic yard. If additional workability remediation is required, add up to 50% of the original dosage of water
reducer if the weather is mile and up to 50%of the hydration stabilizer if the weather is hot.
c) Adjust subsequent loads: Radio back to the batch personnel and relay water and/or admixture adjustments.
d) Determine Consistency: Determine ASTM C1688 unit weight and compare against required values. Unit weight values
greater than 10 pcf different from the desired values may indicate that an incorrect mixture may have been delivered.
If the mixture was correctly batched, but the unit weight is high, hold the truck while slowly mixing for 15 minutes. If
the unit weight is light, adjust workability. In most situations poor flow through the inverse slump cone will indicate
potential for low unit weight values. Adjusting for workability will improve unit weight.
e) Discharge
Using testing for final acceptance
Use the new ASTM standard (spring 2011) testing voids in hardened concrete on the test panel and comparing it to the final
product could be one method for acceptance, +5 pcf. Assuming the test had been performed on the test panel and
established as a goal for the project.
21Chapter 6
Pervious Concrete Construction
Equipment & Tools
NOTE – the equipment and tools listed herein are most familiar in the Kansas City market. New pervious equipment and
tools are being developed constantly. New screeds, curing methods, new hand tools, forms, filter fabrics, etc. need to be
reviewed and tested. If a contractor can show alternate methods of placement and curing to reach the desired durability
and permeability, acceptance should be considered.
Figure 6.1
4 oz. nonwoven filter fabric Roller screed Cross Roller Cross roller on left & joint roller on right
Soy bean curing agent Securely anchor 6 ml poly Conveyor belt placement Hand tamping edges
This list herein contains the major construction materials and tools needed to successfully place pervious concrete.
o 4 oz. (minimum) Non‐Woven Geotextile Filter Fabric
(check to make sure water can pass through the fabric)
o Roller Screed (must be able to be filled with water or sand for weight)
o Cross Roller
o Flanged Roller aka “Pizza Cutter” to cut joints in plastic pervious concrete
o Soy Bean Oil Curing Compound (also use for bond breaker on forms etc.),
Coverage 200 to 250 sq. ft. per gallon (comes in 5 gallon bucket)
o 6 oz. (minimum) Poly Sheeting
(Must take the time to prepare the poly & pre roll onto tubes to roll over the forms behind the screed)
o Conveyor Belt (Pervious can’t be pumped, a conveyor expedites the construction process significantly even for
small jobs)
o Squared ended shovel
o Concrete rakes
o Come‐a‐longs
o Hand tampers
o 2 X 4’s to hold plastic sheeting in place
o Sand bags or equal to hold 2 X 4’s
o Water source and hose
Test Panel Placement & Approval
Test panel placement and approval approximately one month to two weeks, prior to pervious construction.
See the Specifier Guide for Pervious Concrete in Kansas City for dimensions and details.
The contractor must use the equipment, tools and crew that will be used in the actual placement.
22 NOTE – The slab will need to cure for 7 days. Then the owner/designer, contractor and testing company will meet to review
the slab, conduct tests and approve the slab. IF it is not acceptable, it will need to be repeated until approved. This will
take another 7 days, etc. Timing of the test slab can affect the overall start date for the construction schedule.
Overall acceptance should be on surface appearance, joint details, thickness, porosity and curing procedures.
Was the mix provided by the ready mix producer workable and acceptable? If not was it adjusted or modified until
acceptable during the test?
Was the contractor ready and using proper tools? Was the placement team size appropriate? Curing practices in line?
Pre‐Construction Meeting
Refer to the Pre‐Construction Checklist in the back of the Specifiers Guide for Pervious Concrete in Kansas City.
Has the Test Panel Placement & Approval be completed and approved? The mix approved?
Conduct the meeting at least one week prior to placement.
GC, pervious contractor, ready mix supplier, excavation contractor, landscape contractor, architect, engineers, etc. in
attendance.
Review the plans, specifications with all parties.
Discuss testing being conducted, test methods, samples, frequency of tests, testing company familiar with ASTM standards
for pervious concrete?, etc.
Discuss weather, as it has a HUGE effect on pervious. Hot or cold weather practices? Curing? Authority to cancel and
reschedule if necessary?
Discuss access to the site for ready mix trucks and conveyor belt for placement.
Review subgrade, filter fabric, base aggregate, base thickness, wetting the base prior to pervious placement, pervious
thickness, jointing, curing, # on crew, etc.
Is there a water source on site (for wetting the base rock immediately prior to pervious placement)?
Discuss the width of the screed, paving in strips, constructability issues.
Is everyone aware that the poly sheeting stays in place for 7 days cure period, without any traffic on it?
Has erosion control been discussed to keep soils out of the pavement once the poly is removed?
Is the landscaper aware that they cannot use the pervious pavement for their staging area for mulch, plants, etc.?
Weather
Figure 6.2
Resecuring poly after 45 mph winds Prevent billowing in the poly sheeting from the wind
Wind? Prepare for the wind. Severe winds in the 20 to 45+ mph range can wreck havoc on pervious placement.
The Contractor shall not place pervious concrete pavement later in the year than November 1 or earlier in the year than
April 1 unless otherwise permitted in writing by the Architect/Engineer.
The Contractor shall not place pervious concrete pavement when the ambient temperature is predicted by the National
Weather Service Point Forecast for the jobsite to rise above 90°F (32.2ºC) during the seven days following placement,
unless otherwise permitted in writing by the Architect/Engineer. These hot days can be detrimental to getting pervious out
of the truck, exposed on conveyor belts, etc. There is an increased probability of raveling on the pervious surface in its
23completed state and possible durability issues. Consider alternative placement times, i.e., 3 am to 6 am, or late night
placements during cooler hours of the day/night. The owner/designer and contractor may need to delay placement in hot
weather.
ACI 305 Hot Weather Concrete can provide some very helpful information. But remember pervious is more sensitive to
heat that conventional concrete.
Admixtures need higher dosage rates in hot weather to work properly. The ready mix producer and contractor need to be
prepared to redose at the jobsite.
Hot weather shortens the time from batching the concrete to when it must be placed on site.
The Contractor shall not place pervious concrete pavement when the ambient temperature is predicted by the National
Weather Service Point Forecast for the jobsite to be 40°F (4.4ºC) or lower during the seven days following placement,
unless otherwise permitted in writing by the Architect/Engineer. ACI 306 Cold Weather Concrete can also provide some
very helpful information, but pervious has some additional needs in cold weather. 40°F is usually the mark where ready
mix producers’ start using hot water. Pervious concrete should be avoided when the ready mix producer has moved to
using hot water for cold weather conventional practices. The hot water “flash cooks” the admixtures, disabling them from
working properly.
Pervious concrete cannot be placed in rain or snow or on a frozen subgrade or base.
Winter months tend to have dry or very low humidity. These conditions will “dry” the pervious out, so curing is extra
important, and needed to be conducted very conservatively.
Placement in severe conditions should be avoided.
Site Preparation
Verify that the site conditions match the plans.
Review the specifications.
Verify grade stakes
Remove organic materials and trash.
Verify locations for drains, piping, underground cisterns, (if applicable) etc.
Cuts necessary to establish proper subgrade level shall not be compacted or subject to excessive construction equipment
traffic prior to coarse aggregate bed placement and may be scarified to improve infiltration rates.
When fill is needed to met proper subgrade level, some compaction may be necessary. Compaction to approximately 92%
proctor is sufficient.
Filter Fabric Installation
Figure 6.3
Filter fabric overlaps 18 inches Filter Fabric up sides and over edges
Refer to Chapter 3, Design Elements for Pervious Concrete, for specifics on the filter fabric and design details.
Filter fabric shall be 4 oz. non‐woven geotextile. This keeps the fines from coming up from the subgrade below and
clogging the base area. It also allows for water to move through the fabric and continue into the subgrade for movement
into the surrounding soils.
NOTE – Product technology is changing to adapt to pervious pavement needs. Keep abreast of new products that may work
to help water exfiltration into the surrounding soils, even in clay soils.
24 Run the filter fabric up the sides of the pervious pavement.
Overlap the filter fabric to the manufacturer’s recommendations (usually 18 inches).
Base Construction
Figure 6.4
Placing clean aggregate base Placing a perforated pipe underdrain Placing clean rock base over filter fabric
Refer to Chapter 3, Design Elements for Pervious Concrete, for specifics on the base materials and design details.
It is critical that the base aggregate be clean washed aggregates that allow the water to move freely in the base section.
AB3 is NOT acceptable in the Kansas City market for pervious base rock; this aggregate has too many fines to work
effectively and efficiently.
Optional drainage systems may be required by the designer, which may or may not tie into the pervious system. Review
the plans and specifications closely. This could be constructed with check dams, piping etc. See figure 3.3.
The material shall be placed in 6 inch lifts and lightly compacted with equipment. Keep movement over the storage bed as
minimal as possible. Install to the required grades.
The base layer surface shall be sprayed with water immediately prior to pervious concrete placement. This keeps the base
from pulling water out of the pervious mix when it is placed. This will protect the plastic pervious concrete from being
jeopardized; it’s curing the pervious from the “bottom up”.
Setting Forms
Figure 6.5
Forms set ready to pave Forms set & joint marked in blue Concrete strips placed in advance for forms for pervious
Forms must be study enough to stand up to the heavy roller screed and placement operations. Typically wood, steel or
aluminum forms are used.
Make sure stakes are 1/2” lower than the top of the forms. This will allow the roller screed to not get hung‐up on a stake as
placement progresses.
The embedded stakes must be anchored well. They must hold up to the stress of the equipment and crew. They may not
allow deflection during placement.
25Size of the Crew
Figure 6.6
Crew size – 9 approx. Crew size – 14 approx. Crew size – 12 approx. Crew size – 12 approx.
A typical crew size for pervious concrete placement with a roller screed is 7 to 14 crewmen, depending on the job specifics:
o One person conducting oversight, managing the arrival of new trucks, coordinating with inspectors and ready mix.
o One in front, keeping the base rock surface wetted down with water immediately in front of the screed.
o One on the end of the conveyor belt.
o Two to four, with squared shovels, concrete rakes or come‐a‐longs to move the pervious in front of the screed,
these people also fill in holes, consolidate the edges and keep a head of concrete in front of the screed.
o Two, one on each end of the roller screed.
o Two, one on each side of the pavement, they cure with both the soybean oil and roll the poly over the surface and
secure the plastic tight.
o One to two, jointing with the pizza cutter and cross rolling the surface over the poly.
Every team member has a job, knows what it is, and knows who is behind him and in front of him in the construction
process to keep in communication with.
Concrete Arrives for Placement
Be ready BEFORE the concrete truck arrives. This product is very perishable. There is no time to add water to the roller
screed to weigh it down, or place forms after the concrete truck arrives.
Is the conveyor belt in place and ready?
If placing the pervious on small jobs directly from the concrete truck, think about the placement direction ahead of time. If
the chute from the concrete truck is running uphill, you are going to be there a very long time getting the pervious out of
the truck! Pervious is placed with one chute down. Two and three chutes will delay the time and ability to move the
pervious.
The concrete truck will need easy accessibility to the site for truck placement to work.
Using buggy’s to place pervious has been done before, however, be prepared as you will lose some of your permeability.
The pervious consolidates in the buggy getting to the actual site and then is consolidated again with the roller screed. It
also physically takes twice as long and it becomes harder to work with quickly. This is not the best method in the high heat
of summer months! Buggies may be the only method to get pervious in tight spots, where trucks and conveyors can’t
reach.
The conveyor belt method works the best and is needed for the smallest of jobs.
Be sure the pre‐approved mix has been ordered and is delivered. Check the batch ticket.
Conduct an inverted slump test, to assess the workability of the pervious.
Make adjustments, if necessary, notify plant of changes made in the field.
Conduct ASTM 1688 to calculate the unit weight. Does it fall within the +5 from the test panel established mix design
weight?
Remember pervious concrete is not the typical 140‐145 pcf as in conventional concrete.
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