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.