Last year we placed a pervious concrete pavement for Thomas Concrete in Atlanta, Ga. and I was asked by Forta to try fibers in the mix. At the time, I was just comparing the difference in the ease of placement, with or without fibers. The placement went as easily with fibers and that was the end of the story.
Later, after the curing plastic was removed, it was decided by Thomas not to saw any joints and “let’s see what it’ll do”. The slab is 60’x30’ with a nasty dog-leg around a utility pole. I was pretty sure that we would get one crack down the middle with a couple of cracks across, but I was positive that we would get one off the dog-leg. And then.......none....., not one crack. A year and a half later and still not one crack.
I think these fibers work after all!
If you have had any similar experiences, please let me know.
We always use heavy amounts of fibers in our pervious concrete, usually some cocktail of PVA fibers &/or fibrillated polypropylene. We pour our concrete for residential applications on the thinner side, usually about 4" for driveways & about 3" for sidewalks & patios. But we also cover ourselves by using plenty of control joints. Either way, never noticed any cracking in our pervious concrete, except one time, in one little area where the base material changed underneath.
ReplyDeleteFibers generally don't make a difference for compressive or even flexural strengths, so I see why they aren't given more attention. It is hard to test for their effectiveness. But I am pretty sure they are effective, if for no other reason than witnessing pervious concrete specimens failing under compression. I am constantly tinkering with mix designs and have tested the compressive strength of thousands of pervious concrete cubes. There is a marked difference in the way cubes fail that have fibers, they hold together & maintain strength for some time after failure.