Mastering Pervious Concrete

Promotion Partner; Riverkeepers

2011-11-23T00:02:00.001-05:00

Looking for local partners to promote pervious concrete? Don't forget about your local Riverkeeper. Like us, Riverkeepers are dedicated and passionate about clean water and are always looking for opportunities to educate the public about clean water issues. Recently I worked with a local Riverkeeper, the Upper Chattahoochee Riverkeeper, to design a new flyer entitled “Pervious Pavement; Solutions for Sustainable Development”. You can download it here: http://www.npcpa.org/#!__reg

This flyer is a great resource for counties, municipalities, and developers in the Atlanta marketplace and it comes from our Riverkeeper, a steward with a very powerful voice.

If you want to find the Riverkeeper in your area, go to http://www.waterkeeper.org/ht/d/OrgDir/pid/210

New NPCPA Website

2011-11-22T23:07:00.000-05:00

http://www.npcpa.org/

Who says that concrete isn't inspiring?

2011-10-13T10:36:00.000-04:00

A poem by Jim Lafond-Lewis.

___________________________________________________________________

Every organization or loose association of people ought to have its poet laureate.

I would like to be poet laureate of the Pervious Concrete Association.
I would meet regularly with the members and the witch doctor.
We would all feel safe and uplifted
or grounded together.
We would mingle in the lobby before meetings.
I would dream enough for all of us,
especially during discussions
of the Maine Department of Transportation's RFPs.
I would draw attention to the sight and sound of ME DOT RFP
and the doctor would conjure the rumble a small airplane would make as it
rolled across a pervious runway in the rain.
Where once it would have been grounded, bogged down in mud,
my poetry will rise off the concrete and fly across Penobscot Bay!

____________________________________________________________________

To read more of Jim's poems go to his page:

A Wrinkled Man - Un Hombre Arrugado

Design for Pervious Concrete

2011-10-04T16:26:00.000-04:00

The next design class will be held at Southface, Atlanta, GA. If you are interested in hosting a class in your area, let me know.

How Much Pervious?

2011-09-26T11:45:00.002-04:00

I’m constantly asked how much pervious concrete is being placed in the US on a yearly basis and I typically respond with “I have no idea”. As I’ve retired from contracting, I haven’t been in the field for the past few years, so for while I lost touch with the market. However, I’ve been working for the Association for a full year now, and what started out as getting a call every other week from someone looking for help on a project, has now become a daily event, at least one call on a pervious concrete project every day. I get so many now that I don’t have time to respond like I used to and I have to direct them to the website to find a contractor.

I’m sure part of this is due from awareness that the Association exists, but the major reason is that the pervious market is exploding. It’s not just the number of jobs I get calls about; it’s the size of them. During the last two months, just three of these projects alone (one in the SE, one in CA, and one in the NE) total over 4 million sf. Never before have I seen the number of projects planned and projects of this size. Will 2012 be the year we top 10 million SF?

ASCC Annual Conference

2011-09-22T11:37:00.000-04:00

Last week I had the privilege of presenting "Troubleshooting Pervious Concrete" to the American Society of Concrete Contractors. I am very impressed with the quality of ASCC and encourage pervious contractors to get involved with this group.

Check out this Kid!

2011-08-18T10:47:00.000-04:00

http://www.northeastern.edu/news/stories/2011/08/jackson.html

NPR Science Friday Talks About Pervious Concrete

2011-07-14T08:50:00.001-04:00

Thanks to Chris Estes for letting us know about this.

http://www.wbur.org/media-player?url=http://www.wbur.org/npr/137397969/creating-reservoirs-under-roads-and-parking-lots&title=Creating%20Reservoirs%20Under%20Roads%20And%20Parking%20Lots

Proper Equipment for Pervious

2011-06-16T14:00:00.006-04:00

What is proper equipment for placing pervious concrete? I you asked me that question 25 years ago I would have said a 2x4 screed. The first time I worked with pervious, in the spring of ’86, that’s what I used; a 2x4 magnesium screed. In fact, we would routinely hand rod pervious, using a hand float as a spacer to strike high and then follow with a static roller for compaction. We quickly learned that a truss screed was a much easier method for larger placements, but we still did our tie-ins by hand with a spreader, a large flat rake. Some jobs were so chopped up, especially when working around trees or on varying slopes, we would use a spreader on the whole job and follow with just a narrow cross-roller.

That is pretty much how it was done until about eight years ago. There were some other contractors trying plate compactors, but as it required placing a really dry mix, and I have always felt that more moisture was needed not less, I stayed away from that technique. Around eight years ago, I started working with a Bunyan roller screed and that became my new normal. David Mitchell w/ Bunyan had been trying to get me to try his screed for years but I had a pretty narrow mind as equipment was concerned. My hesitation to try the roller screed can be blamed on two things; 1) the type of mixes we working with; drier, pound into place mixes and 2) my idea that there was only one “best way” to do things.

As admixture companies began developing new products for pervious and making the mix more fluid; the options for equipment choices grew and I soon realized that there are many “best ways”. To explain what I mean, consider the debate of “prescriptive vs. performance”.

At its core, the idea behind “prescriptive” is that there is one “best way” to accomplish the goal. The problem with this idea is that this is not necessarily true. In fact, we spend a lot of time trying to get designers to go to performance based specifications because we know we can reach the goal more often without prescriptive requirements limiting our options. The same is true with equipment for pervious. When we “prescribe” the equipment, we lose focus on performance and we fall into the same trap that prescriptive designers find themselves. We say “they want their cake and eat it too”. Well now we know how they feel. It’s a tough choice, but we have to choose whether we want to control how to do it, or else set the standard for performance. And speaking from experience, the installers will figure out how to get it done with their equipment if we give them clear defined goals.

Today, there are even more equipment choices out there. Lura makes a lighter aluminum roller screed, Somero makes a pervious concrete head for the laser screed, and who knows what tomorrow will bring concerning pervious equipment, mixes, admixtures, uses, etc. By limiting options we can literally hold pervious concrete technology back, but by focusing on performance, we can allow pervious concrete technology to continue to advance and become an even better product.

So what is proper equipment for placing pervious concrete? Today, I say whatever gets the job done.

Auburn University Continuing Education

2011-06-15T10:51:00.008-04:00

The first Auburn University Continuing Education class, “Design for Pervious Concrete”, has been scheduled for July 15, 2011 in Atlanta at the Georgia Association of Water Professionals. The program description is as follows:

This one-day program will provide participants a detailed understanding of pervious concrete stormwater systems and its use as a low impact paving alternative. It will discuss issues affecting successful design with pervious concrete, including mix design, sizing, hydrology, siting, site preparation and post placement landscaping, layout, certain aspects of placement execution, and long term care and maintenance. The course includes two workshops; in which the participants form teams and design and specify a pervious concrete stormwater system. This course should be of direct interest to those in the Civil Engineering and Landscape Architecture fields, including county engineers, city engineers, public works officials, transportation engineers, DOT personnel, consultants, and all those with responsibilities for stormwater design and control.

The course will soon be offered around the country.

For those of us who are promoters of pervious concrete, this course is a "must attend" as it is one of the required courses for “Pervious Concrete Professional” designation, a credential that identifies someone who has advanced knowledge of all aspects of pervious concrete. Design for Pervious Concrete was developed through a partnership with NPCPA and Auburn University and will be offered in various cities throughout the country. Each class will have instructors provided by both Auburn and NPCPA. Recently I sent out a request for instructors and received good response, but more are needed. If you have experience in teaching pervious concrete programs and would like to help, please contact me.

Stormwater: What’s the Big Deal?

2011-05-18T13:17:00.004-04:00

Sometimes we get so caught up in our own world that we lose sight of other's perspective. I was reminded of this last week while meeting with the Upper Chattahoochee Riverkeeper along with Jimmy Cotty, Executive Director of the Georgia Concrete & Products Association. Jimmy suggested that we refer to pervious concrete formally as a stormwater system instead of a pavement system and instead of having a specification for Pervious Concrete Pavement, we should have a specification for a Pervious Concrete Stormwater System. I thought this was an interesting proposal because it really focuses on the perspective of those concerned with stormwater. Then I began to wonder if we really understand the perspective of the stormwater professional?

To illustrate this, let me relate an experience I had in 2009. I was invited to Seattle, WA to help write a pervious concrete guide document for Puget Sound in association with the Puget Sound Partnership and Washington State University. This was my first time to the Pacific Northwest and I was looking forward to spending a few extra days as a "turista" and seeing the natural beauty of the Puget Sound. So, after my release from the committee work in Tacoma, I headed north through Seattle and took the ferry across Puget Sound and made my way to Kingston. I was awestruck at the beauty of it all. Yes, I was on a boat and that contributed to my positive experience, but the fact is the Puget Sound is truly a treasure.

Of course, as a proud tourist, I grabbed as many brochures of the area as possible and I also took note of any newspaper articles concerning the Sound, especially anything concerning water quality. Now keep in mind that I am from Atlanta so I had a pretty good excuse for my ignorance of the issues facing the Puget Sound, although it didn't take me long to discover the issues. Each morning, on the front page of local newspapers, there were reports concerning the Sound and its precarious condition. There were stories about oysters not reproducing, a story about toxic chemicals, even one about the "Tacoma Aroma". There was also a story about the $50 million budgeted yearly to stop pollution from entering the Sound, mainly from stormwater, and how more was needed. It was evident to me that the locals had a pretty good assessment as to where the Sound was and where it needed to be as it relates to its wellbeing.

That's why I was surprised by the responses I received from locals when I asked their opinion as to the health of the Sound. Most seemed to be unaware of any threat to Puget Sound.

Consider this...every year, roughly 52 million pounds of toxic chemicals are washed into the Puget Sound from such things as cars and boats leaking oil. To put this into perspective, the equivalent of a Exxon Valdez size oil spill is taking place every eighteen months in the Puget Sound. Congress has created a special Puget Sound office within the EPA with its main emphasis on trying to get a handle on controlling stormwater runoff into the Sound.

So what about you. Are you aware of the stormwater issues in your area? If you are involved with pervious concrete in any way, I encourage you to reach out to stormwater professionals in your area and support their initiatives. It's an ideal way to gain their perspective.

New Ways to Cure Pervious

2011-05-11T10:08:00.006-04:00

Curing pervious concrete is no doubt one of the most critical aspects of a successful placement. Historically, the curing has been done with plastic sheeting covering the pavement for 7-10 days. For lack of a better alternative, this method is the standard even though it comes with many disadvantages. One of the main downside to using plastic sheeting is the amount of plastic that goes into landfills. For every SF of pervious concrete cured this way, 1.2 SF of plastic will be used. Yes, recycling is an option but we have to admit that hardly no one (if anyone) recycles their plastic. Every once in a while, if the plastic is not damaged, it will be reused but eventually it gets thrown away.

Then we consider the placement restrictions that plastic sheeting puts on the installer. Use of the plastic forces the installer to pour in strips and produces all those construction joints, by far the hardest joints to keep from raveling. Some feel these joints have poor compaction and some feel they have insufficient curing, but whatever the cause, I say minimize the joint and you'll have less problems. And of course we need to consider the labor costs and impact that plastic curing has on the project schedule. At least one week after placement, someone has to remove the plastic, and this phase of the project is stalled for the curing week. Although no traffic should be allowed on the pavement, sawing and/or stripping could take place during the curing phase if not for the plastic sheeting. Again, many disadvantages.

Thankfully, there are other ways to cure pervious that I expect will soon be available if not already. Here are some that I am aware of:

One manufacturer is developing a biodegradable plastic curing sheet for pervious concrete. One manufacturer has developed a sprayed on curing compound combined with a densifier for improved surface durability. Many are aware of the internal curing admixture that I have been using for years but also saturated lightweight sand is being used in pervious concrete for internal curing (expect ACI report on internal curing soon).

Using these curing techniques individually or combined should prove to be an advantage to pervious concrete, providing the benefits of curing without the disadvantages of traditional plastic sheeting.

2011-05-06T08:58:00.000-04:00

Pervious Concrete Needs _______?

What is the number 1 need for pervious concrete right now? Training for installers? Training for producers? Better tools? Better standards? Better Design? More testing? More environmental laws? Better economy?

What do you think? Give your thoughts on this at the NPCPA LinkedIn site. linkedin

Infiltration Fabric for Pervious Concrete

2011-03-24T14:53:00.002-04:00

This week at ConExpo/ConAgg, Propex announced the introduction of a completely new class of non-woven geo-textile: PERC Pervious Concrete Infiltration Fabric.

According to Propex, PERC is specifically designed to assist in the effectiveness of pervious concrete applications with enhanced water flow properties and permeability, but with low pore size to trap soil. Made from 100% recycled PET from soda bottles, the fabric's smaller pores restrict dirt and particulates from contributing to clogs, which reduces maintenance in storm drains.

Most contractors are aware that some sort of fabric is needed to maintain separation between the softer, less compacted soil base and stone filter layer, however, sometimes there is confusion over what fabric to use for pervious concrete applications and where to buy it. Now contractors and installers can order it right from their ready mix supplier and have it delivered to the site.

This is great news for pervious concrete systems but what really excites me are the tremendous growth implications for designers using LID strategies. There have been attempts to use aggregate gradation to maintain structural integrity of the system, which is easy enough to design but impossible to construct. The fabric is engineered to provide structural support to the pavement, while allowing stormwater to infiltrate, but it also has the ability to "wick". Technically this is referred to as "capillary action". It is the same process that allows water to go up a tree to its leaves. For projects that have pour soils, this is big news.

When rain falls on these projects, very little is infiltrated unless the site is perfectly flat (and sites are never flat). Imagine a site with soils that drain at 0.1" (one tenth of an inch) per hour. This is a soil that we would basically call non-porous. Especially when the rain that comes in contact with it runs on down the slope. The trick is getting the water to maintain contact the soil long enough for infiltration to take place. Historically, hard to do, but now, very easy. The fabric will literally pull the water against gravity and spread the stormwater up the hill, maintaining contact with the soil for infiltration over the whole site. That means a site with these poor soils will infiltrate 2.4" per SF over a 24 hour period, even on a slope! I watched a demonstration of this capillary action and saw the water go up a 60% slope!

Use of this fabric will help increase the market for pervious concrete in areas with soils that infiltrate less than ½ inch per hour and the kicker is it is made with 100% post consumer recycled content. Each roll of PERC uses 3,350 plastic soda bottles. And no, color is not added. Green is its natural color.

Good Observations

2011-03-18T16:02:00.000-04:00

Today I had a Producer send me an email about a project that was just completed. It's good to find Producers that care enough to go back and look at the job with the goal of improvement. His observations/comments were as follows:

"Now that the poly has been removed I went and walked the parking area that the installer placed (about 1000 yds. 8" thick). The overall pavement looks very good with the exception of two items: 1) There was a lot of hand work (adding additional material and hand tamping) at the edges (construction joint) of each lane. This left an overall darker appearance highlighting each lane (maybe 18" wide). This area also concerns me for potential raveling as evidenced by some loose aggregate. 2) The saw joints did not originate at the joints in the curb and also were not continuous across pavement. Some of the cuts went through 2 lanes then was offset by several feet and resumed. There is one crack in the lower area of the pavement originating at a sewer manhole cover. This is not an official report, just thought you would be interested. Again the mix looks like it will perform very well and the placing and finishing work looks very good for the main part of the lanes. Maybe some education on treating the construction joints and developing a joint plan is in order."

These are good observations that could probably be seen at many sites around the country, and yes, more education is needed.

I'll address these two issues in upcoming blogs, working edges and installing joints.

Pervious torture for surface abrasion

2011-02-24T12:35:00.000-05:00

The New Test for Permeability ASTM C "911"

2011-02-22T14:00:00.004-05:00

ASTM C "911"

Lunch & Learn Prime Time

2011-02-21T22:37:00.000-05:00

Is there such a thing as the "Prime Time" for a lunch & learn? I think I may have discovered it, the optimal time for a L&L! And what's more, I'm not talking about going to the client's office. No,no, during "Prime Time", they'll come to you. And be careful how many you invite as they all may show up!

If you are a promoter, you are well aware of the basic lunch & learn formula;

Attendance = Topic X Interest + Free Food / Schedule

Or you could say that no matter the topic, interest or food, the schedule is the critical factor. That is why we promoters go to the clients for their L&Ls. If you've ever tried to get them to come to your office for a L&L, you know how hard it is. Some of us reason that if you have a really good topic or if you have really good food you can get them to come. I've tried it and it doesn't work. Once I had a group of 20 that wanted to learn about pervious concrete and they all loved sushi, so we had $500 worth of fresh sushi delivered for a pervious party. 2 showed up. I learned my lesson, and from then on I've been doing the deli sandwiches at their offices, just like everyone else.

And then I discovered the "Prime Time". I was part of a L&L where we invited a local water professional association's stormwater committee. We expected 20 or so and how we were surprised when 78 showed up! For pizza at that!

So when is this "Prime Time". Look on your calender and find a Monday that is a Holiday and schedule your L&L for the Friday before. It's as simple as that. By the time the L&L is over there isn't enough time to go back to the office, so they'll "just go back to work on Tuesday". From their perspective, this is the perfect way to begin a long weekend!

Give it a try and let me know how it works.

Call for Instructors

2011-02-07T16:43:00.000-05:00

Auburn University (AU) and the National Pervious Concrete Pavement Association (NPCPA) is seeking qualified professionals to provide classroom instruction in the Design for Pervious Concrete (DPC) program offered Nationwide. Qualified instructors must have experience in the design, construction or production of pervious concrete. It is expected that qualified instructors will be offered the opportunity to provide between four and eight full days of training in the calendar year for the DPC program. By becoming a DPC approved instructor, an individual can gain increased visibility among practicing professionals, access to a network of fellow instructors and teaching resources, and the opportunity to earn CEU's.

Those interested in becoming a DPC Instructor should submit their qualifications, experience, and honorarium requirements to NPCPA. For more information, please contact me at:

dfisher@npcpa.org
770.309.6649

National Pervious Concrete Pavement Association
125 TownPark Drive, Suite 300
Kennesaw, GA 30144
404.835.7190 P
404.835.7199 F

Pervious Concrete Mix Design Calculator

2011-01-27T14:03:00.000-05:00

The Pervious Concrete Mix Design Calculator was handed out World of Concrete and was a big hit with the attendees. It assists producers in developing quality pervious concrete mixes based on their local materials. It is also a good tool for the contractor to compare theoretical vs. actual density (which in effect becomes a yield measurement tool). If you were not able to pick one up at W.O.C. and want one for yourself, contact me at the following address:

Dale Fisher, Executive Director

National Pervious Concrete Pavement Association

125 TownPark Drive, Suite 300

Kennesaw, GA 30144

dfisher@npcpa.org

World of Concrete 2011 - Pervious Concrete Student Competition

2010-11-18T09:42:00.002-05:00

The pervious concrete student competition will take place this year at WOC in an effort to provide quality pervious concrete for the Pave ll Save Habitat for Humanity Service Learning Program while maintaining continuity with pervious concrete placements. Teams are challenged to create a pervious concrete mix design and submit a specimen for judging which is aesthetically pleasing while maximizing durability and maintaining good permeability. The mixes will incorporate products manufactured by Sponsors of the Pave ll Save program and the winning mix will be used for pervious concrete driveways and sidewalks to upwards of 600 homes throughout the service year.

Prizes: Three prize categories are offered, Aesthetic, Durability, and Permeability. The prizes for each category are independent of each other and teams may win in one or more categories. First, second, and third place entries in all categories will be awarded a certificate of recognition, will be recognized in Concrete Construction magazine if space allows, and will be recognized on NPCPA's website. For each category, the first place team will receive a $250 award, and the second place team will receive $100 award.

In addition, a Grand Prize will be awarded to the team with the best overall balance of all three categories. The winning mix design will be used on the Pave ll Save service learning program for one (1) year. The Grand Prize team will receive a $250 award, a one year NPCPA membership and be credited for the Habitat for Humanity mix design in all NPCPA media relations. Each school shall be eligible for only one prize per category.

Each entry consists of one specimen sized to fit in a medium USPS flat rate shipping box. Attendance at WOC is not required.

For more information contact:
NPCPA
125 TownPark Drive, Suite 300
Kennesaw, GA 30144
404.835.7190
404.835.7199 Fax
info@npcpa.org

***ADDED 11/18/2010***
Forta has grabbed the Fiber Sponsorship spot. Forta did a test on tuesday with their macro-fiber using 2.5 lbs/cu yd of the 1 ½” length. They reported that it mixed extremely well and uniformly, and would love to see several of the student groups play with even higher dosages and/or longer lengths.

What's your Watershed?

2010-10-18T18:11:00.002-04:00

Can you name your watershed?

We all live in one; an area that drains to a common waterway, such as a stream, lake, or even the ocean. Perhaps you're like me and never really thought about it, but why is it we all know our state, our city, and our street, and yet, we have no idea what the name of our watershed is.

What would you think of someone that didn't know the name of the town they lived in? You would probably question their mental state. A better question is, what would it say as to their citizenship? I've been thinking a lot about this lately and, because we promote low impact development (pervious concrete), I think our watershed should be known. So here it is, my new address:

Dale Fisher, NPCPA, 125 TownPark Drive, Suite 300, Kennesaw, GA 30144, Etowah Watershed 03150104

Click here to find your watershed.

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DNR Loves Pervious Concrete!

2010-10-12T18:49:00.001-04:00

Carroll County will be required to pay more than $100,000 to the Environmental Protection Division of the Georgia Department of Natural Resources. The EPD is requiring the County to install pervious concrete along new road.

Read more: Times-Georgian - County to pay EPD more than $100,000 in fines.http://www.times-georgian.com/view/full_story/9775501/article-County-to-pay-EPD-more-than--100-000-in-fines-?instance=TG_home_story_offset

Mix Challenge

2010-10-04T10:46:00.000-04:00

Good answers all! First increase the stone to 27 CF (dry rodded unit weight x 27) to correct the yield, then, if needed, remove cement to increase voids.

Mix Challenge 2

2010-09-20T13:22:00.002-04:00

Here are the poll results of the Mix Design Challenge:

16% said Mix will perform as designed...
33% said Yield will increase...
33% said Yield will decrease...
16% said Mix will appear wet...
50% said Mix will appear dry...

As you can see, the majority thinks that the mix will not perform as designed and they are correct, but as for what will happen to the mix seems to be a guess. 50% of those polled think the mix will be dry and, as for the yield, half think it will increase and half think it will decrease.

The correct answers are: The mix will appear wet and the yield will decrease.

I'll explain why.....

In our example, the gradation changed without the producer's knowledge. So what started as yard of pervious concrete with 2,700 lbs of aggregate became .95 yards of pervious concrete with 2,565 lbs of #89 limestone aggregate and 135 lbs of sand (this explains why the yield will decrease). The mix is batched with 600 pounds of cement which translates to 600 lbs per .95CY or 632 lbs per CY. It has 21 gallons of water (175 lbs) per .95CY or 22 gallons per CY. The water/cement ratio stays the same but the sand will increase the paste volume from .22% to .26%. The voids will decrease to 15% and, seeming to seal easily, "jelled" spots will appear and make the the mix look as if it is to wet, and indeed, if any water is added to the truck, it may seal completely (these "jelled" spots are a good indicator that there are unplanned fines in the mix).

Now here's the next challenge. How do you fix it?

Look at this week's Poll and try to pick the right answer or answers.

Mix Challenge

2010-09-06T10:52:00.005-04:00

Consider an example of a pervious concrete project using a #89 crushed limestone aggregate with a specific gravity of 2.70 and a dry rodded unit weight of 100 lbs/CF. The mix is designed and produced with 2,700 lbs of stone, 600 pounds of cement and 21 gallons of water (175 lbs). This mix has a cement/aggregate ratio of .22 with 22% paste by volume (water/cement ratio of .29). Admixtures are used to control hydration and improve workability and so the mix is easily discharged from the truck and easily compacted due to its "fluid" nature.

Now here comes the challenge....what would happen if we threw in 5 lbs/CF of sand (into the stone at the quary) without the producer's knowledge? In other words, what if the gradation changed in this way during the course of the project?

Look at this week's Poll and try to pick the right answer or answers.
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An Old Dog Learns a New Trick

2010-08-23T00:35:00.004-04:00

For years I have been asked about fibers for pervious concrete and I have always answered the same. “No comment”. It’s not that I didn’t think fibers were of any benefit, it’s just that I really didn’t have a strong opinion either way. I’ve placed projects with fiber and I’ve placed projects without fiber, and both have performed well. I’ve read literature that says fibers help in this or that way, but I’ve never been in a situation that I could tell hands down that fibers made pervious concrete better. Not until now.

Last year we placed a pervious concrete pavement for Thomas Concrete in Atlanta, Ga. and I was asked by Forta to try fibers in the mix. At the time, I was just comparing the difference in the ease of placement, with or without fibers. The placement went as easily with fibers and that was the end of the story.

Later, after the curing plastic was removed, it was decided by Thomas not to saw any joints and “let’s see what it’ll do”. The slab is 60’x30’ with a nasty dog-leg around a utility pole. I was pretty sure that we would get one crack down the middle with a couple of cracks across, but I was positive that we would get one off the dog-leg. And then.......none....., not one crack. A year and a half later and still not one crack.

I think these fibers work after all!

If you have had any similar experiences, please let me know.

Symposium on Pervious Concrete

2010-08-19T14:13:00.001-04:00

Papers are invited for a Symposium on Pervious Concrete to be held Sunday, December 4, 2011. Sponsored by ASTM Committee C09 on Concrete and Concrete Aggregates, the symposium will be held at the Tampa Marriott Waterside in Tampa, Florida, in conjunction with the December 4-7 standards development meetings of Committee C09.

For more info go to:
http://www.astm.org/SYMPOSIA/filtrexx40.cgi?+-P+EVENT_ID+1822+/usr6/htdocs/astm.org/SYMPOSIA/callforpapers.frm

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NPCPA - Why Now?

2010-08-02T10:44:00.001-04:00

The question of how NPCPA will function without duplicating the efforts of existing organizations has been asked by many in our industry. It is a great question and it really focuses on not only the "how?", but also the "why?" as well as the "why now?".

I agree that our industry organizations have been instrumental in the development and promotion of pervious concrete for the better part of this last decade. Nine years ago, ACI formed committee 522, which has produced both a Report and Specifications for pervious concrete. Five years ago, NRMCA adopted the role of trainer with the development of the craftsman certification program and the Association's National Resource Directors have taken the lead in national promotion through the National Accounts Program. Three years ago, ASTM formed the pervious concrete sub-committee for writing pervious concrete standards. In addition, PCA and ASCC, as well as many regional, state and local associations, groups, and individuals have supported and contributed their resources to promotion of pervious concrete.

It is undeniable that the cement/concrete industry is proud and supportive of its child, the "green sheep of the family". And coming from someone who has been involved with pervious concrete for more than 25 years, we have done an incredible job taking pervious concrete to its current level. We in the cement/concrete industry have always been aware of the financial benefits to our industry (e.g. cement companies sell more cement, concrete producers sell more concrete, concrete contractors install more concrete) so we have a vested interest in pervious concrete as a result. And, perhaps because of this interest, coupled with pervious concrete being non-proprietary, we as an industry feel that we "own" pervious concrete. However, I propose that we change this thinking.

Now, before there is a call to burn me at the stake as a heretic, please let me explain.

Through the efforts of those previously mentioned, we have long touted the environmental and financial benefits of pervious concrete to regulators, specifiers, designers, and owners. In fact, we have marketed pervious concrete as the pavement of choice for true sustainability and the market has responded, not only by accepting pervious concrete, but by producing “champions” that actively promote and campaign for “our product”. This begs the following questions:

1. Do the purchasers (or owners) of pervious concrete pavements have a vested interest in pervious concrete, as they are concerned with product quality as well as life cycle and maintenance?
2. Do the designers and specifiers of pervious concrete projects have a vested interest in pervious concrete, considering their reputation may be affected by the product’s success, or lack thereof?
3. Do the regulators who pass ordnances requiring use of pervious concrete have a vested interest in pervious concrete?

If, like me, you answer yes to these questions, you realize that pervious concrete really “belongs” to everyone that has this vested interest. And when we as an industry come to that realization and capitalize on it, just imagine what we can accomplish in promoting pervious concrete.

The designers and specifiers that have a voice in NPCPA will “champion” pervious concrete to their clients and among their industry leaders through groups like ASCE, AIA, ASLA and USGBC. The owners that have a voice in NPCPA will “champion” pervious concrete to their industry leaders through groups like RILA and NEWH. The regulators who have a voice in NPCPA will “champion” pervious concrete among their communities and to their peers through groups like APWA and AWSPS.

Any clear thinking business person would agree that this is a worthy aspiration. However, previously, we did not have an adequate vehicle to accomplish this goal. PCA, as a cement association, has no allowance for these “voices”. NRMCA, as the voice of ready mix producers, is also not fitted for these groups. Likewise, ASCC (contractors) and ACPA do not provide a place for association. In fact, we as an industry, primarily, only associate with our market “across the table”. As you may see, we have a missing piece in the pervious concrete puzzle.

NPCPA is uniquely shaped to fit in this puzzle, allowing us to develop and support champions outside our industry. Working alongside and in support of ACI, ACPA, ASCC, PCA, and NRMCA, NPCPA fills the gaps in our collective efforts in advancing pervious concrete. NPCPA provides a venue for interchange to all those vested in pervious concrete. As founding members of NPCPA, our existing industry associations will sit on the same side of the table with outside industry groups that are turning to pervious concrete to meet their sustainable goals.

Many today feel that the economy is on the upswing and will continue to improve. Now is the time to build these relationships, before the market gears up and is too busy to change its status quo. It is my hope that all those in the concrete industry will join NPCPA and will help build lasting relationships with the users of pervious concrete.

Pervious Concrete Champions

2010-07-26T16:11:00.003-04:00

Shoreview Public Works Director Mark Maloney named CEAM Municipal Engineer of the Year

Posted by Release in Public Works

At the City Engineers Association of Minnesota (CEAM) Annual Conference, Mark Maloney, Shoreview Public Works Director, was named Municipal Engineer of the Year, which honors the special achievements of municipal engineers.

Mark has more than 25 years of engineering experience, including the past 15 years as Shoreview Public Works Director/City Engineer. During Mark’s tenure at Shoreview he has been involved in many significant projects that have greatly improved the quality of life in the community. Projects include road and infrastructure improvements for the Rice Creek Corporate Park, expansion of Shoreview’s trail and sidewalk system and most recently the innovative use of pervious concrete surface to infiltrate stormwater in a smaller lakeshore neighborhood, which received national recognition.

Recognized by his peers, MnDOT Commissioner, Tom Sorel, was one of many to recommend Mark for the award. Sorel wrote, "Mark is a strong visionary in his field. He understands the value of creating a sustainable transportation system that will be responsive to the needs of future generations of Minnesotans."

Mayor Sandy Martin presented Mark his award and said, "Mark is unique in his combination of expertise, pride and personal and professional ethics. It truly is a pleasure working with him."

Pervious Concrete Association

2010-07-12T12:08:00.002-04:00

Although the past few years have been tough on many in the concrete industry, we see the light at the end of the tunnel. We have seen a marked increase in the National interest and demand for pervious concrete over the first half of this year. This demand is equivalent to the growth period of pervious concrete in the southeast in the mid/late 90s.

Historically, the marketplace has dictated the growth of pervious concrete through its demands. Pervious concrete has grown from localized grassroots efforts to a macro-environment with interest at both the Federal and State level. Recently several DOTs have advanced from lab testing pervious concrete and have progressed to not only writing specifications, but actually letting and constructing pervious concrete pavements, replacing their traditional asphalt pavement. We are on the threshold of explosive growth of the pervious concrete marketplace.

Therefore, I'm excited about the timely formation of the National Pervious Concrete Pavement Association. The Association has not been organized to work against or separate from groups that have developed pervious concrete to its current state. It has been organized to stimulate and advance the common interests and general welfare of the pervious concrete industry. It is organized to work closely with associations like ACI, ACPA, ASCC, NRMCA, and PCA to meet this collective goal.

Membership is open to any individual, entity, firm or corporation engaged in the concrete construction industry as a contractor, architect, engineer, consultant, developer, owner, technician, student, manufacturer or supplier of materials, products, tools, equipment or services, and any affiliated trade or professional association.

For more information, go to npcpa.org

Airports - Unpaved Runways

2010-06-16T21:38:00.013-04:00

Although not the focus of this Blog, from time to time I'm going to voice my opinion on subjects that I feel strong about. The subject of pervious concrete & airports is one of them.

It seems that when this subject comes up, inevitably comments turn to loose stone and jet intakes. Yes, large jet aircraft land on unpaved airstrips in third world countries, and yes they do have to put stone guards on the engines, and no we don't want the liability, and yes there's the jet fuel, and yes, and yes, and no, and no......

These concerns of some are valid as they apply to commercial aviation, but let me be very clear...what we are talking about is general aviation. General aviation covers a large range of activities, both commercial and non-commercial, including private flying, flight training, air ambulance, police aircraft, aerial firefighting, air charter, bush flying, gliding, and many others. Experimental aircraft, light-sport aircraft and very light jets have emerged in recent years as new trends in general aviation.

I still remember my first experience flying. I was five years old and I sat in the back seat of a J-Cub behind my dad while we did touch-n-goes on a grass airstrip/cow pasture with the side windows folded down. I was traumatized for years. Years later, after I flew the coup, he bought a 200+ MPH Mooney and we were able to fly all over in style. I grew up in Lakeland, FL, home of "Sun-N-Fun" the southeast's premier fly-in, so flying was a large part of my early years. My dad no longer flies due to medical reasons and long ago my wife clipped my wings. Perhaps one day......

Anyway, my point is, there are many general aviators out there, taking off and landing on, not only concrete and asphalt, but also on grass, dirt, sand, and gravel.

In fact here are some statistics on general aviation in the US:

Number of:
Student Pilots........................84,339 (2007)
Private Pilots.......................228,475 (2007)
Piston Engine Aircraft.............163,743 (2007)
Airports w/Paved Runways..........5,174 (2009)
Airports w/Unpaved Runways.......9,921 (2009)

Don't be quick to close your mind to this market. As you can see, most runways in the US are unpaved. They are grass, dirt or gravel, with the majority being gravel. Averaging 2000' in length, these unpaved runways represent approximately 600 million square feet! So if you come across anyone in general aviation asking about pervious concrete, please don't shut the door on the opportunity, it could be huge.

Here is an example of a project that is an ideal fit for pervious concrete:
http://www.workingwaterfront.com/articles/Improvements-planned-for-island-airstrips/13728

By the way, concerning last week's poll, the majority (75%) likes tooled joints.

Cleaning Pervious Concrete

2010-06-10T14:51:00.004-04:00

Kentucky Ready Mix Concrete Association just uploaded this video of the cleaning of their parking lot.

Minimum Cement Content

2010-06-07T12:21:00.008-04:00

Question of the Week (5/31/2010): What should be the minimum cement content for pervious concrete?

Poll Results:
700 lbs. ld/yd3 …………… 0%
600 lbs. ld/yd3 …………… 38%
500 lbs. ld/yd3 …………… 12%
None of the Above………. 50%

The NRMCA Pervious Concrete Certification program correctly states that “500 to 600 ld/yd3 would be a good starting point…..and further fine tuning can be accomplished by the concrete producer”.

In the early days of pervious concrete promotion, statements were made about proportioning mixes, specifically 600 lbs/CY as a good starting point. This idea seems to have carried itself along and wound up in many documents about pervious concrete and ultimately in the minds of specifiers. And what started as a "starting point" became a "minimum" in the conservative mind. Not surprisingly, the poll result reflects this mindset.....38% chose 600 ld/yd3.

You need cement to make pervious concrete, however, caution should be taken when specifying minimum cement content. The producer needs the freedom to develop his mix design based on locally available materials and its' available gradations. Although I typically work with mix designs containing 500-600 ld/yd3, some aggregate gradations I’ve worked with required less than 500 ld/yd3. In fact there are some mixes (high sand) that require less than 400 ld/yd3!

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Be sure and take part in the new Poll: What is Your Preferred Joint for Pervious Concrete?

Yield....the dirty little secret

2010-06-01T09:00:00.005-04:00

It's somewhat of a balancing act to develop a pervious concrete mix that places easily, performs well, and has good durability. Finding this balance requires the producer to develop mix designs for each of his aggregates and also have the ability to adjust the mixes on-the-fly based on field density tests. Unfortunately, a concrete producer or contractor that doesn't have the experience or ability to make these adjustments, will have problems on the job site as the aggregate gradations will typically change during the project. There may be yield issues, mixes that wont drain, mixes that ravel, and the list goes on.

As for yield issues in pervious concrete, understand that changes in aggregate gradation always affect the yield. I'll say it again for emphasis....changes in gradation always affect the yield. If the gradation becomes more uniform in the mix, the yield increases...if more fines are introduced, the yield decreases (it could be as much as 5% and still meet common specs). I should note that pervious concrete mixes rarely become more uniform during the course of the job, but typically mixes increase in density as the gradation changes.

This is really a lose/lose scenario from the producer and contractor's perspective. Not only will the producer waste material like cement and admixtures (I'll explain later in another post), but the contractor will work harder to place a mix that will under-yield (I'll explain this later too). This is why I encourage good communication between the producer and the contractor, good quality control, and do your density tests.

Remember pervious concrete's dirty little secret......keep the gradation under control or your yield will be out of control!

Earth Day 2010

2010-05-28T09:12:00.004-04:00

This Earth Day (April 22nd) I had the privilege of training Auburn University Students, AU Facilities and the City of Auburn as they were certified as NRMCA Pervious Concrete Technicians. Professer Michael Hein of AU's BSCI (Building Science) has done an impressive job educating and promoting pervious concrete in the Auburn community. So far AU-BSCI has trained and certified over 75 future users/specifiers of pervious concrete!

Here are some photos of Auburn's contribution to Earth Day 2010...

Michael Hein (AU-BSCI) and Bobby Maddox (AU Facilities)

The Crew!

For More Photos Go To: http://picasaweb.google.com/aubscipervious/DuckSamfordPerviousPavingSpring2010#

Integral Color: Liquid vs. Powder

2010-05-26T09:36:00.010-04:00

I’m often asked what method of coloring pervious concrete works best; liquid color or dry powders? There seems to be a trend in the industry to suggest that one is superior over the other, mainly liquid being the better choice. I’ve heard explained that this is due to liquid being better distributed in the mix, especially in drier mixes. This makes sense to me, but I have to question why anyone would want to place a dry mix.

I’ve found that both systems work equally well, but if given the choice, I’ll use dry color and I’ll explain why….

Dosage rates for regular concrete and pervious vary greatly as the color in pervious is not competing with sand. For example, an 8 CY load of regular concrete (4 sack mix) requires five (5) 25lb bags of color (4% rate) but an 8 CY load of pervious concrete (600 lbs/yd) could be colored with just one (1) 25lb bag, for the whole load.

I’ve used heaver doses with pervious but I’ve found that the extra color is a waste of money because of the process of curing pervious concrete. It seems that no matter how much color you put in the mix, the pavement will be bleached when you remove the plastic sheeting. But here's the trick...spray on a matching color-cure after the curing sheet is removed and you'll have the best looking pervious you've ever seen. This method makes beautiful pervious concrete.............. and you’ll save money!