Stone Wall Foundation Fire

[440MoPar]

I have a project involving a structural evaluation where a fire occurred in a corner room. The flame traveled up the exterior wall, which is made of field stone. This wall was built in 1803. Is there any documentation on the heating/fire affects on stone, stone walls/foundations and its mortar? I am aware of NCMA TEK manual 07 and Fire Protection Planning Reports but I haven't found anything specifically on stone/rock or the like. Any suggestions? or documents that I am unaware of?

 

[ishvaaag]

From

Fire Safety Engineering
Design of Structures
Second Edition
John A. Purkiss

"5.2.5 Masonry
There appears to be little data on the strength of masonry at elevated temperatures although some data are also available on residual properties (section 13.3.1.5). The residual property data suggest that the strength degradation in the mortar is likely to be the controlling factor in strength performance of masonry, but this has not yet been demonstrated by test as far as the author is aware.

...

13.3.1.5 Masonry
There are few data on the residual strength of masonry, but those that are available indicate that clay bricks lose virtually no strength at 1000?C, whereas concrete and calcium silicate bricks lose around 75% of their
strength and mortar has no residual strength at 1000?C (Lawrence and Gnanakrishnan, 1988a, b). Türker, Erdo?gdu and Erdo?gan (2001) report test data on residual strengths of mortar which indicate that for limestone or quartzite mortars the strength loss is around 20% at 500?C, 65% at
700?C and 80% at 850?C. For lightweight aggregate (pumice) mortars, the figures are no loss, 40% and 50%."

So I would conclude that the damage is to be similar at least to the small loss of mortar given, and likely more; what makes me to think that is that cracking at the mortar beds is likely due to enforcement of compatibility of deformations at the extreme temperatures attained, so we are not dealing with a masonry units (here stone) properly set within mortar beds anymore; the beds are damaged.

Respect the effect on the stone itself you know that calcination is used to produce lime from carbonaceous stone, thus losing strength; so it will depend much on the kind of stone.