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.