Along the way, there will be hands-on training for contractors that want to get a real feel for how to place pervious concrete. Sessions are offered Tuesday through Thursday at 10:30 am, 12:30 pm, and 2:30 pm, and on Friday at 10:30 am. During these sessions, attendess will work with instructors to learn how to place pervious concrete, and use the appropriate tools and equipment. A performance evaluation will be offered to those seeking NRMCA Installer certification, and this will qualify as one of three required projects necessary for that certification.
Come see how to do it right and wrong! At 'Pervious Concrete Live!' visitors can see what is new in the market for pervious concrete tools and equipment, and see demonstrations of maintenance equipment, screeds, and test procedures. Contractors can walk the slabs of pervious concrete to see how it's done right, and how not to place it.
For the official overview of everything pervious, look at Woc's website.
For most, December brings about thoughts of snow, holidays, and good times with family and friends. However, for concrete wonks, December gets us excited for ASTM meetings!
Subcommittee C09.49 met yesterday at ASTM's winter meeting in Atlanta to continue development of testing standards for Pervious Concrete. Here are a few highlights:
1) Fresh Density (ASTM C 1688): While there were ballots to resolve some language, and nuances of the test, the real action here is the continued push to add the Marshall hammer as an optional compaction tool. in the original round robin to develop the test method, the Marshall hammer was technically on par with the Proctor hammer with respect to variability and results to compact the sample. By allowing the use of the Marshall hammer, the subcommittee will link 1688 and 1747 with a single compaction tool. The subcommittee should expect to see a ballot on this early next year.
2) Raveling Resistance (ASTM C 1747): The subcommittee is still working through the new business items generated by negative votes from the previous ballot. The significant change derived from this may be an option to compact the specimens to 1688 density rather than design density.
3) Hardened Density (ASTM C 1754): This task group is, likewise, still working through the new business items generated by negative votes from the previous ballot.
4) Surface Infiltration (ASTM C 1701): There was a good discussion regarding changing the language in the Significance and Use section to encourage the test to be used for acceptance of the surface of the pavement. So, it would be used to prove that the surface drained, yet would need to be coupled with cores, especially when placed directly on a sandy subgrade, to prove that paste drain hadn't sealed off the voids at the bottom of the concrete layer.
5) Compressive Strength: The task group is looking to one last, final round robin based on the data that has been generated to date. Some of the details look like they will stick based on earlier testing. The procedure will first be published only for lab specimens. Samples will be capped with sulfur or gypsum. All specimens will be weighed and compacted to the C 1688 density. The subcommittee discussed whether to focus on 4X4 or 4X8 cylinders to compact with the Marshall hammer. The decision was to evaluate 4X4 cylinders compacted in a single lift with the Marshall hammer compared to 4X8 cylinders compacted in two lifts with the proctor hammer.
6) Flexural Strength: Mr. Glaspey presented some data on compaction of pervious concrete flexural specimens. The subcommittee discussed looking at smaller specimen dimensions. He discussed having more data and a draft of the standard by the next meeting.
The next meeting of this group will be June 10, 2013 at the JW Marriott Indianapolis; Indianapolis, IN USA.
After six years of service, with his term as chair complete, Dr. Obla led his last meeting of this group. He leaves with a great record of helping to develop four new test standards in that time, while laying the foundation for two others. On behalf of the industry, we owe a big 'thank you' to Dr. Obla for his hard work. The incoming subcommittee chair was announced at the end of the meeting, and this author is proud to take on the task.
With the committee chair's trip canceled at the last minute, a surprise guest chaired the Fall 2012 ACI 522 meeting -- me!
Here's what happened:
1) While a little behind schedule, the committee continues to make progress on the third version of ACI 522R. Based on where we stand, I'd guess the committee is still a year away from submitting to TAC. Norb Delatte reported his task group will submit a draft that includes structural design tables.
2) The standard details are coming closer to reality. The original intent behind this was to create a stand-alone document to post online on the CKC, however, with the timing of 522R, it is more likely to be added as an appendix to the next version of 522R.
3) I'm happy to report the committee successfully balloted its response to TAC comments. The debate lasted over 2-1/2 hours covering exciting topics like internal curing, adoption of ASTM C 1754, basis of purchase, and responsibilities.
While it's the third year of the Bunyan Pervious Roast, it is my first year attending. Based on what I'd heard, I wasn't sure if it was more of a lecture series, day-long demonstrations, or an R&D event?
One day in, it seems to be more of a group think-tank. Sure, it's a chance for those new to pervious to learn all about it. It's also an opportunity for contractors to try new tools and techniques. Most significantly, however, it's a place for the industry to come together, to discuss the future of pervious concrete, in all aspects: mixtures, construction techniques, testing, specifications and research.
Don't let the tent in the desert fool you, this is the place to be! Congrats to Dave Mitchell and the Bunyan crew for putting on such a powerful event.
Late last year, the EPA issued Washington DC a new MS4 stormwater permit. As described in the press, this is the model they hope to follow moving forward as it strongly encourages low-impact development stormwater management techniques. Recently, the city published proposed amendments to their Municipal Regulations to guide adoption of the new permit. These guidelines are even more progressive than the new permit, and it will be interesting to watch over the next few years to see how the market adapts to a credit/trading system for stormwater management. It's also interesting to see that the district proposes to ban all coal tar sealants. You can learn more about it all here, and read the text of the permit here or the short version here.
These are the highlights for me: I like this part: "Ensuring that local codes, ordinances and other policies are consistent with the requirements of the permit is critical element of success. A number local governments attempting to implement green infrastructure measures have found their own local policies to be one of the most significant barriers, e.g., parking codes that require over-sized parking lots, plumbing codes that don’t allow rainwater harvesting for indoor uses, or street design standards that prohibit the use of porous/pervious surfaces. EPA has published a document, the Water Quality Scorecard ( http://www.epa.gov/smartgrowth/pdf/2009_1208_wq_scorecard.pdf ), to assist local governments in understanding and identifying these local policy barriers and also provides options for eliminating them. EPA is not requiring the District to use the Scorecard or any other specific method, but recommends a systematic assessment of local policies in the context of the requirements of the Final Permit in order to comply with the provisions of this Section."
...and this part: "One of the fundamental differences between today’s Final Permit and earlier permits is the inclusion of measurable requirements for green technology practices, sometimes referred to as “low-impact development” or “green infrastructure.” These requirements, which include green roofs, enhanced tree plantings, permeable pavements..."
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.