I find it complicated. It's not exactly the plastic providing
the support but the plastic is containing a granulate
that is taking the support. (The hex structure is famously
strong, even used in XB-70 wings).
Perhaps we should calculate the bursting strength of
one of the hexagon cells. Using 700#/sq.in, which is
approximately the load bearing of soft wood. When
struck with a hammer gets dented, iow's the hammer
blow exceeds the compression strength of the wood.
If I were to take a hexagonal shaped thingy into one
of the hexs filled with sand, and struck it equally hard
would the plastic hex burst?
If that's a fair test, off hand, I think it will survive.
IMHO, I think the spec is ok.
(Where's good ole Bob Morrison when we need him?)
A lot of words that don't say very much, and what they do say is
Obviously the product is intended for creating a drivable green
surface. Thanks for clarifying that - the name grassy paver had
"It is assumed that the underlying soils..." That's your idea of
engineering? ASSuming bearing capacity and soil conditions?
An 18 wheeler typically weighs in at around 80,000 pounds maximum load
(federally mandated maximum).
An average semi tire has approximately 60 square inches of contact
area - that's ~7.5 SF of tire contact area per truck, or roughly
If that grassy paver stuff has a rating of TEN times the maximum load
allowed on federal highway - with the graded, layered and compacted
base - why the nifong do they use asphalt and concrete for roads?
Your grasp of the numbers is as faulty as the manufacturer's claims.
Move on - please. This is getting embarrassing.
Interesting, having drove many interstate miles
you get to notice the right hand lane has more
tire dents. I suppose the surface temp in a hot
sun could hit 120F, certainly can't walk on it in
bare feet, so maybe more. Maybe that creates
It costs to nifong much.
Anybody gotta a nifong industrial sized press?
Did you notice the load claims at "high" and low temperatures? The
high temperature was 75 degrees. Where's that supposed to be and
what's it supposed to represent? HDPE softens considerably with
temperature. They don't attempt to make any disclaimers about
climate. What do you think would be a normal high temperature for a
paving product? I'd guess about 20 degrees higher than 75.
It'd cost a fraction of a real road and would shut all the greenies
up. Someone would have suggested it and there'd be test roads under
I don't doubt there are plenty of locations and applications for their
stuff. It's just the ridiculous claims that are nifonged.
I visited the website & emailed the guy (he posted below) about the
claims being made.
He sent me a link to some info from the mfr (he jut sells them)
looks like the mfr had some tests done on the plastic unit (filled &
un-filled) AND the mfr (or their agent) did some hand waving based on
the ASSTHO H-20 loading
And then extrapolated the results to some of insane psf number
the guy who signed the test report is some sort of clueless
Phd.......reporting numbers with 6 or 7 "significant" figures,
reporting psf's that no soil in the world could possibly support
Using the ASSTHIO loading & then extroplating to a generalized psf is
like calc'ing the stress under a woman's high heel & extrapolating to
a psf for floor loading!
120 pounds, assume .375" diameter heel tip, standing equally on both
540 psi translatesto >>>>>> 78,200 psf
makes as much sense as their test report & product claims
What they really have is a product that can take a higher "point
load" (actually a local small patch distributed load) than normal
(unconfined / un-reinfornced) soil.
With the plastic grid & grass roots, you wind up with a reinforced
soil that (IMO) is at best is a few times stronger (locally) than
regular soil MAYBE 20 or 30 psi
but it ain't asphalt or concrete!
hehheh You obviously don't wear heels.
You forgot to account for the sizable percentage of weight on the balls of
Why do I suddenly feel like Reese Witherspoon in Legally
I was considering the load case when "she's" rocking on her heels. :)
I didn't consider the dynamic effect of foot fall "impact" while
I think i also may have over estimated the heel tip diameter (I'm
wearing flats today & didn't measure or reseach tip dia)
in any case I'm sure you get my example........heel tips are hard
even oak floors so my number of ~540 psi is in the ball park
You have no idea what's in my closet.... :)
I knew you were kidding me.
& I just pulled the example out of the air..... I divided the weight
bu two but I also chose 120lbs (wishful thinking?) ...could have been
I refuse to go measure the heel tips...even too geeky for me.
The roughly 180,000 lbs of a Boeing 747 is dispersed over 26 (?) tires of
which about four or five sq ft (each)come into contact with the
Maybe they're promoting their stuff to firms building major airport runways?
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