KBI flexi-pave

I have samples of the material. Impressive stuff. Not sure how it would work in serious freeze/thaw conditions.
 
I'll try to post some pics. It comes in different colors and is mixed, poured and worked like concrete. Uses a polymer binder. It has some "give" to it. We are considering it to replace turf in a downtown median that sees a tremendous amount of foot traffic that is affecting several large median trees.
 
The problem with these semi-permeable pavements is the entrapment of small sediments inside the pore spaces of the material. Here at UConn we have a parking lot paved with a semi-permeable concrete material and it has excessive ponding due to the pores being filled with sediment. and anywhere used where runoff comes into play, sediments can cause the same problem. They are a great product in principal but their application takes certain locations to be fully effective.
 
Good point that never occurred to me. That would be a major problem for the application we are considering and the project cost would be well over 100K. I guess I'll have to rethink this.
 
According to their web site once the surface is silted in you can clean it and restore it back to 100% by vacuuming and sweeping. Now Im sure that your wife's Dirt Devil will not do it but they say its 100% recoverable. How fast they silt in depends on location and use. I wonder if water freezing into it causes a problem? I would imagine it would stop drainage, but what about damage.
 
I've never installed (or for that matter seen in person) this particular item, but I did a bit of research into pour-in-place crumb rubber for playground surfacing. The "best" manufacturer/install combination that I found was done over grooved concrete with a mesh between the crumb and the concrete. The mesh was to prevent the crumb from filling in the grooves and the grooves provided for drainage. They had 2 methods of cleaning, the basic vacuuming, then they could also flood the pad and use a pool vacuum. Considering the porosity, there probably doesn't need to be the drainage groove level, but it most likely helps. Vacuuming without the pass-through from the grooves would probably have at least some bleed laterally from the areas yet to be cleaned.
 
being an elastic polymer (in this case its recycled tires) freeze thaw damage should be minimal with a properly maintained surface. Freeze thaw damage hits hardest where there is undrained pore water in a material, think water inside a crack in a concrete pier or water filling a bored hole, as that water freezes and expands it adds internal stresses to the material causing freeze thaw failure modes such as de-lamination and spalling. In a porous material like this flexi-pave there seems to be enough pore space to both prevent the accumulation of excess pore water as well as available airspace for the expanding water as it freezes to dissipate the internal stresses better. and using an elastic binder such as tire rubber will allow more of a range of distortion of the material before permanent failure happens (think of being able to bend asphalt emulsion in pavement compared to portland cement binder in concrete)

this practice happens currently in the concrete industry, there are certain chemicals called admixtures, one of which prevents freeze thaw damage by increasing available pore space in the concrete to lessen the internal stresses due to internal ice buildup.

-Steven
 
to the contrary, if there is an area of this material that hasnt been maintained and the pore spaces have begun to silt in due to normal environmental reasons or other, then the drainage aspect (which prevented freeze thaw damage in the first place) is gone allowing water to build up in the pore spaces thus providing a perfect scenario for freeze thaw damage, water built up in pore spaces (holes cracks/ natural or designed in the material) allowed to freeze in a material that doesnt have the distortion/displacement abilities to dissipate the internal stresses.

-Steven
 
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