Pervious Concrete: The Road Less Raveled

Typical Results when Testing Pervious Concrete by ASTM C 1747

Now that ASTM C 1747 is 6 months old, it's encouraging to see people actually using it, and testing their pervious concrete with it.

The most common question I hear is, "What is a good result for C 1747?"
In a perfect world, I would be able to answer this question precisely; however, we still don't have enough field data to say what might be indicative of a good pervious concrete mixture. Until then, here are a few guidelines:
1) The best result I've seen is ~19%.
2) The Worst result I've seen is ~100%. (You can't have over 100%, but I'm waiting for somebody to report such a result.)
3) The average result from the ASTM round robin, for mixtures with 20% voids was ~39%.

If you have any data you can share, please email me or post it as a comment below.

Changes to NRMCA Pervious Concrete Contractor Certification Policy

It would be cool to say that the committee that oversees the NRMCA Pervious Concrete Contractor Certification is a super secretive society that flies in for monthly meetings, in their cloaked rocket planes, to meet in a remote, hidden underground fortress. But, in truth, it's a much more pedestrian group of designers, contractors, and concrete producers that have irregular conference calls to provide guidance to the NRMCA on changes in the market and technology that might impact how they run their certification program.

In our committee meeting last month, we made some minor changes to the policies that govern the program for both installers and craftsmen:

For installers, the policy has been clarified with respect to participation in demonstrations and hands-on training events. "Applicant’s participation in a pervious concrete demonstration or hands-on training may only count for one (1) of the three (3) required projects." To draw the line between 'demo' and real project, if the pavement goes into service, then it is considered a live project, even if it was cast as part of a demonstration. This was done to encourage contractors to get hands-on training while ensuring they had suffiecient live project experience.

For craftsman, nothing has changed, yet. However, the committee is crafting policy to limit the submittal of applications through local LSG's only. This would give more local control to the certification process and prevent national entities from signing off on a craftsman application for a contractor whose work might be hundreds of miles away. The paperwork requirements for craftsman applications will continue to be cumbersome, but with 38 certified craftsmen and 145 installers, this is not an excessive hurdle for such a critical specification requirement. Further, the craftsman application still requires the approval of a 3-member certification committee of the LSG. These individuals are responsible for ensuring the applications is truthful, and that the contractor has actually done the work detailed in the submittal.