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Re: warehouse slab/ CA stamp

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The problem with using sand as a base course is that all the particles are about the same size,  therefore they don't really compact well.  It stays together when wet,  but when it dries out, it falls apart.  This is just about the time the concrete mixer will be driving over it,  leaving big ruts.

What  most people want for the base course is something that is pretty evenly graded,  kind of like the diagrams that you see for concrete aggregate,  where you have smaller aggregates filling the voids between the larger aggregate.   This helps it to compact nicely,  rather than act as ball bearings.  There are various names used for the material used for base courses - M10s, dusty 12s, (these refer to sieve size) crusher run, etc.

Sometimes, people use material with fairly large aggregate for the base course,  then they spread a layer of finer aggregate on top to lower the coefficient of friction.  Doing this makes a slightly better capillary break.

You do need about about a four in. layer of this material though,  a two in. layer will not compact really well.

Re: wet stamping.  My understanding is that you have an original signed document  (not a copy),  not necessarily embossed.  When you (or more exactly, I) submit plans to DC for example,  I need to sign each set.  I cannot sign a set,  and then make copies.  Some agencies require things like contracts to be signed in blue pen, so that it is obvious it is not a copy.    

Although this is a pain,  I don't necessarily think it is a bad idea.  I had a job recently where the contractor (who was required to submit PE stamped shop drawings)  simply cut the signed (but undated) stamp off of the first submittal and xeroxed it onto all their subsequent submittals.  

Gail Kelley