Pervious Concrete

Certification, what does it mean?

Due to the recent increase in interest in Pervious Concrete including the EPA listing it as a BMP (Best Management Practice) for managing storm water and recycling it into the aquifer, the shortage of qualified pervious installers has become obvious. Many Industry Associations, Tool and Admixture providers are trying to remedy the problem by establishing training programs to teach concrete installers how to install pervious concrete. Usually they are programs that last a day or two at the most and include faulty procedures which have produced failures in the past. After passing a written exam they issue a “Technician Certificate” for “Pervious Concrete Installation” to anyone who passes the examination. More than 1600 technicians have been issued certificates. Most have no experience installing Pervious Concrete!

Many of those teaching these technicians have not demonstrated that they have an acceptable skill level installing pervious concrete, or have had no experience working in the field with the material. If a ready-mix truck brings defective material they may not even know it.

We do appreciate the efforts of the various groups and individuals trying to get more qualified installers into working with pervious concrete. Unfortunately the idea that with a few days training, big bucks can be made is a bad concept! So is the idea that a few new tools, a new admixture or some other gimmick will turn any concrete crew into a team of pervious craftsmen is going to do much more harm than good for green building and sustainability concepts.

Currently the Florida Concrete and Products Association makes the following statement to introduce its list of Preferred Certified Contractors: “To qualify to be listed as a Preferred Contractor, a company must have at least 1 current employee certified as an NRMCA Pervious Concrete Craftsman or 2 employees as Technician.” To qualify a contractor’s technicians to install pervious concrete under this criteria would be like taking 2 students who just passed an accounting course final exam, and then qualifying them to form a CPA practice. Where is the experience factor?

At least they do also qualify Pervious Concrete Craftsmen who have at least 3,000 Hours of experience installing at least 10,000 square feet of pervious concrete. The quality of that work is not addressed. We well exceed that requirement with more than 30 years experience installing pervious concrete throughout Florida and the Southeast.

As shown by the photos below, some of these certified technicians have used that certification to sell themselves as Pervious Concrete Contractors. The work below, after one month shows raveling due to lack of compaction, lacks minimum porosity in some areas, and may involve product containing too many fines or too much water. The result is that this pervious concrete does not function, gives the product a bad reputation, eventually gets torn out or covered with asphalt or can result in costly litigation. And a project earning LEED points for pervious concrete, may not be entitled to them, with work like this. Those now certified need to get a few years experience working for an experienced pervious craftsman, before trying to run a pervious crew.

Example #1
Poor Example #1
Example #2
Poor Example #2

Photos of work completed about a month earlier under the direction of a “Certified Pervious Technician” employed by a paving contractor. Example #1 shows lack of porosity, raveling, poor compaction, evidence of too much water in the mix and improper curing. Example #2 shows raveling, cement paste smeared on surface by the use of improper tools, a control joint that is already raveling and aggregate which was not properly dispersed and compacted into the slab.

Below is properly placed Pervious concrete installed by us about a year before this picture was taken. Note the uniformity, integrity and porosity of slab. This is being used for parking on a daily basis.

Good Example #1
Good Example #1
Good Example #2
Good Example #2

We have been certified as Pervious Installers for many years prior to the relatively new certification by NRMCA. This was done originally by R. M. C. Ewell, Inc. and more recently by Cemex now by the National Ready Mix Concrete Association. More importantly we have more than 25 years experience installing pervious concrete. We were the first to publish a Pervious Concrete Specification and make it available on the internet. Please review our Pervious Specification.

That’s why we offer a 10 year warranty on Pervious Concrete we install. A sheet of paper given to anyone taking a test after one or two days of training in comparison to Charger Enterprises’ wealth of knowledge is like comparing the qualifications of a handyman to an experienced building contractor. Many concrete contractors who are now certified technicians are installing pervious concrete materials that are destined to crack or ravel. Don’t let this happen to you. Insist on references and evidence of a minimum of ten years of experience installing Pervious Concrete to the satisfaction of engineers and general contractors.

True, more Pervious Concrete Installers are needed, but they need to work under someone experienced for a few years before hanging out their Pervious Contractor shingle as shown by the comparison of work displayed here.

Raveling in Pervious Concrete installed by "Certified Craftsman" using roller joint tool
Raveling in Pervious Concrete installed by “Certified Craftsman” using roller joint tool
Saw cut joint from pervious concrete installed by Charger Enterprises over three years prior
Saw cut joint from pervious concrete installed by Charger Enterprises over three years prior

We are always making progress!

Pictured below is our new heavy-duty pervious concrete pavement. The proprietary mix was developed with our Pervious Partner CEMEX. Making use of slightly larger aggregate with fewer fines, our new mix design is made for heavier loads, less chance of raveling and greater porosity. Depending upon base soils, this pavement should let rainwater pass through at over 15 gallons per square foot per minute.

Heavy-duty pervious concrete pavement
Heavy-duty pervious concrete pavement

We have chosen to qualify for the NRMCA certification to show appreciation for the effort they are making to educate the concrete industry about Pervious Concrete and to try to improve the quality of the pervious concrete being installed. However, the requirements to become preferred contractors must be tightened to provide the credibility certification should carry.