I have been following this one for the past few days and have wondered
about the freeze-thaw connection to terra cotta damage in general and
glaze-spalling in particular.

As some probably are aware, a fair percentage of our annual revenues
are derived from providing custom materials for reprofiling and glaze-
matching spalled, but otherwise sound, glazed terra cotta and brick. We
seem to get just as much of this kind of work in places like Florida,
S. Texas and California where there is essentially no freeze-thaw as we
do in the worst cold environments. I am, accordingly, duly skeptical
that freeze-thaw has anything to do with it.

The decision to replace with porous brick, seems to me, to be akin to
the decision to replace terra cotta with precast concrete, or something
else. I see it as the lazy decision, one which requires less planning,
and which may make the system a little less sensitive to proper
detailing for the near term, but which is which is just as likely to
suffer from lack of proper problem investigation, detailing and
resolution over the long run. And in the course of a decade or so of
exposure, the precast (or other replacement) begins to look like what
it is, rather than what it was intended to look like, which is terra
cotta.

Mike E.

>
> In a message dated 12/19/2002 9:19:00 AM Eastern Standard Time,
> [log in to unmask] writes:
>
>
> > <<<The co-op's board of directors learned in February that decades
of water
> > damage had left 40 to 65 percent of the blue bricks cracked and
poised to
> > crumble on pedestrians.  The details of "cracked and poised to
crumble"
> > would be interesting to know.  Also, who it was who said this was
the case.
> >  It is our experience that there are some firms who do Local Law 11
> > inspections which, shall be say, take liberties with the truth
Unlike the
> > porous red bricks Some red bricks are porous, and some are not.
Some might
> > even be glazed. , blue bricks are coated with a thick I haven't
seen too
> > many THICK glazes, and wouldn't be surprised if there aren't many.
> > Although a thick glaze might be more problematic than a thinner
one, the
> > basis result either way is that the impervious glaze traps moisture
(which
> > may enter the brick through cracks in the brick or from the mortar)
within
> > the brick because the moisture can't migrate out through the face
of the
> > brick.  The result is that the glazed surface, or whatever
thickness of
> > brick which adheres to the glaze, spalls off.  The loss of the
glazed
> > surface generally leads to continued and accellerated frost damage
to the
> > rest of the brick.  However, in the case of Altman's, we have found
that
> > once the (relatively thin) glaze spalls off the body of the brick
(in
> > pieces about the size and thickness of a potato chip), that the
remaining
> > body (or "biscuit") is stable and does not appear to be subject to
further
> > deterioration.
> t glaze that traps water runoff. When that water freezes, it puts
pressure on
> the bricks, Because water in the teeny little voids (or within the
cores in
> newer brick) is trapped within the brick, the pressure (due to
expansion of
> water frozen in the voids) is more typically applied within the
bricks,
> causing them to disintegrate; this is not the same as causing their
> detachment from the backup wall, to which there may or may not be
adequate
> masonry ties, and which also may have rusted away if the wall was wet
enough.
>
> > weakening their attachment to the underlying concrete Are we talking
> concrete or concrete block here, Mr. Want to Know It All? wall.>>>
> >
> >
> > Question to BP: Is there a way to detail glazed brick so that it
does not
> > create moisture problems? As my esteemed colleague pointed out,
there are
> > many ways to detail masonry which can improve the performance; I
doubt
> > there is A way that everybody would agree on for all
circumstances.   This
> > is part of the reason why architecture requires careful thought,
> > resulting in different different solutions to the same problem.
And one
> > doesn;t learn this stuff in school, or from a computer program, and
maybe
> > not from a hotshot design office-- the best way to learn it (IMHO)
is
> > through correcting other people's mistakes. There's an astonishly
early
> > (1930) white glazed brick building (as plain as anything form the
1950's)
> > at 270 Broadway (@Chambers) without any evidence of spalling or
failure,
> > even at the many parapets.   FKC did some remedial work on that
building,
> > which I think is a state office building, a few years back.  The
geezer who
> > ran the job has since retired [this is a guy who left a camera on
the
> > sidewalk, walked away, and was surprised when it wasn't there 5
minutes
> > later] and I don't remember  what was wrong with it.  However, it
probably
> > needed the usual corner repairs dues to rusting columns, and
probably some
> > spandrel, lintel, flashing and parapet work.  If the parapets are
still (or
> > again) good, it's likely due to good copings.
>
> Ralph>
> >
>
>
>

Edison Coatings, Inc.
M. P. Edison
President
3 Northwest Drive
Plainville, CT 06062  USA
Phone: (860)747-2220
Fax: (860)747-2280
email: [log in to unmask]
Internet: www.edisoncoatings.com

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