GeologyRocksTravertine and thermal shock
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Travertine and thermal shock
Fri, 02/11/2005 - 16:33Hi Altyfc, welcome to the boards!
Interesting problem. The main problem lies in that your builder could be right. If the heating was too high, then thermal shock could cause cracks in the tile and these would propagate along any weaknesses - mainly the joints in the plywood under the tiles.
However, limestone (of which travertine is a type) has a very low thermal expansion coefficient (2-6 micrometres per centigrade) - I can't envision temperatures below 100°C causing instant thermal shock. However, your heating tiles may well cause large fluctuations in the temperature of the tiles on a daily basis, obviously smaller than 100°C, but over a prolonged period of time this could still cause thermal shock. Whether this could cause cracks to appear in just one year, I honestly do not know.
Sorry, I couldn't be more helpful. Hopefully someone else can be! 
Jon
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Travertine and thermal shock
Sat, 02/12/2005 - 02:52Since the cracks coincide with the jointing of the plyboard, it sounds as if that hasn't been properly secured and this cracking is due to flexing of the ply. :shock:
How thick are these tiles?
I would have thought that travatine was not a good stone to cut tiles from. In many cases quarrymen and advertisers call stones by names which are geologically inaccurate.
I would guess than anything less than half to threequarters of an inch would be too weak. That means a terrific weight of tiles anyway. :?
I have a lovely purple and cream banded 'lump' of about 10 lb, which is polished on the 'visible sides'. It is extremely crystalline. With this crystallisation, I would have put my piece down as a marble personally, but since I got it from Dr Chris Alabasta (Bristol Uni) I certainly am not prepared to argue. He has probably forgotten more about the mineralisation of the area than I will ever know.
It is from somewhere in the north Mendips to south Gloucestershire (perhaps Yate area), but for some unknown reason Chris would not be more specific. :x Strange that!!! 
John
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Travertine and thermal shock
Submitted by Anonymous on Fri, 02/11/2005 - 11:12.Hello
I would be very grateful if anyone can help me with the following:
About a year ago we moved into a new build. In the bathroom to the master bedroom, we had travertine floor tiles laid down on top of underfloor heating mats. Since then, the tiles have cracked (in straight lines) in multiple places. We strongly feel that the floor has not been prepared properly (indeed, on excavation, we discovered he has used 9mm ply instead of the recommended 16mm) yet the builder is adamant that we are partly to blame for having the underfloor heating on too high, saying that we have subjected the tiles to "thermal shock". Quite frankly, I think this is nonsense, but I would be grateful for a geological perspective on this.
1. For travertine to be thermally shocked, or detrimentally affected by temperature in any way, what would the temperature need to get up to?
2. If travertine were to be thermally shocked, how would this manifest itself in the tiles? Our tiles are cracked in straight lines (and those lines happen to co-incide with joins in the ply laid down beneath).
Thanks very much for any pointers you can give...