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Granular Layer over Vapor Retarder

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Gail knows how I feel about putting anything over a sheet material---it is a
pain in the butt, expensive because it is labor intensive, etc.

But anyway---when you specify a gradation, I suggest you look carefully at
what is available in the market where the project is located; many quarries
run only what they have demand for every day, and when you ask them for
something different, the answer is either:
	No. We do well enough with our bread and butter runs, we don't want
to reset our screens.
	Yeah, we have something like that, but only about 235 tons. You said
you needed 1200 tons? Oh, well, sorry. We got that gradation once by
accident when some screens jammed. It's been in a pile in the back for 5
years; glad to get rid of it. Too bad we only have one fifth of what you
need. Any more? No. (see above)
	Well, we could re-set our screens for that, but you'll have to wait
about 6 months because we are trying to stay up with our orders for #57, #8,
etc.
	
We recently saw a specification for a layer using NJDOT I-3 material. It is
a material set at 60-100 at 3/4 in sieve, 30-100 at No. 4, 5-35 at No. 50,
0-8 at No. 200. Sort of like masonry sand only a little more coarse. And, of
course it was completely unavailable from any quarry in a 100 mile radius of
the site. 

The A/E was very confused; they had developed the specification based on
recommendations of the Geotechnical Engineer. (As an aside, the A/E was from
Chicago, the GE was from Michigan, and they admitted that they knew nothing
of the availability of materials for the local market, they looked at the
NJDOT manual and found something they thought looked pretty good so they
specified it. NJDot basically says that they have gradations that they think
are good ideas but that particular gradation was "not one in  popular use"
as the district engineer we contacted could not recall ever seeing it used
on roadway or storm projects)

Yes, it was available, but not within the time frame that the project
required (the 2 quarries that were willing to run it had specifiec windows
when they would consider doing it, related to re-setting their screen
sets)and both were more than 100 miles away; and the cost was 4x that of  a
more available material on top of the trucking costs.

We suggested a PaDOT 2A layer (100 at 2in, 52-100 at 3/4, 36-70 at 3/8,
24-50 at No.4, 10-30 at No. 16, 0-10 at No. 200)from a quarry 32 miles
distant.
And it was accepted. We gave back a negotiated credit of a couple of bucks a
ton.

So---check your desired gradation with local suppliers, and if it is an
unusual one, manage the expectations of your client (Architect, Owner,
GC/CM) that there is a premium involved.

By the way, the same thing applies to special gradations for aggregate for
concrete. Quarries think as described above, and plants often only have
limited silos or bins, so "custom" aggregate runs, while possible, are
difficult. We have been told point-blank that it is not worth their while to
empty their bins of "standard" (say, #57)aggregate to re-fill with a custom
blend when they make out fine with profits from their everyday 3,4,and 5 ksi
mixes. It is just not worth it to them.



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