>At Finlandia Hall in Helsinki, designed by the great
>Alvar Aalto, the Carrara White marble cladding all
>bowed.  After 20 years, the panels were all cupped up
>to 50mm (2") over a 1800mm (6') length.  That is, the
>centre had gone back into the building, and the ends
>had come out.

Same thing at the Amoco (formerly Standard Oil) building in Chicago, an 80
story tall box which was originally clad in 1-1/4" Carrara marble. When it
went up in the mid 70's I said it wouldn't last 10 years. I was off by 40%;
it lasted 14 years. They had to spend about 100 million dollars (Late
1980's dollars) to reinforce the structure to hold heavier cladding and
then they used 2" North Carolina white granite.

The explanation I heard is that, since the diagonal of a square is longer
than the width of the square, equal expansion in all linear directions of
the slab causes a greater total expansion on the diagonal than on the X and
Y axis, and so the corners cup outwards. I was told that these 1-1/4" slabs
were held with clip anchors into slots cut in the edges, meaning there was
between 1/2" and 5/8" of meat on either side of ths slot. Therefore, just
1/8" to 3/16" of cupping would start popping the stone around the slots.

When the stone was being removed, loads of people called me with get rich
quick schemes for the scrap marble, which all involved them coming up with
an idea (ash trays, paper weights, trinkets) and having me do all the work
with that marble, and we'd split the take. I didn't lose any money or sleep
on any of those deals, I turned them all down.
____________________________________
Walter S. Arnold  * [log in to unmask]
Gallery:        http://www.stonecarver.com
Gargoyle postcards: http://www.stonecarver.com/postcard.html

--
To terminate puerile preservation prattling among pals and the
uncoffee-ed, or to change your settings, go to:
<http://maelstrom.stjohns.edu/archives/bullamanka-pinheads.html>