[Bell Historians] Steelwork into masonary

[Chris Povey]

Burying steelwork in masonry is fundamentally very dodgy.
There is a lousy thermal miss match causing differential expansion
problems.
Rod Bickerton, 22/2/07

Sorry, Rod, this is untrue. Perhaps surprisingly, there is a close similarity between concrete/stone/brickwork coefficients of expansion and mild steel. It's why we can embed steel in concrete to make reinforced-concrete. If the CoEs were very different, the steel would either expand at a greater rate than the concrete as temperature increased, causing it to buckle and crack the concrete, or the opposite, which would pre-load the steel and make it fail early. The following coefficients of expansion (taken from Kempe's Engineers Year Book) will illustrate the point:-

mild steel: CoE 11.0 x 10-6
concrete: CoE 13.0 x 10-6

For comparison: copper 16.3 x 10-6 and aluminium 23.0 x 10-6

Concrete actually expands fractionally more than steel. 

(Did some work on this a few years ago and obtained CoEs for masonry and brickwork, but can't turn them up now. They were similar to concrete - which is effectively stonework anyway.)

Steel beams embedded in tower walls have no problem thermally. Actually, the temperature inside a tower rises comparatively little compared to the outside temperature, because it's in the shade. On this basis there are potentially more thermal expansion problems within the walls themselves, from what can be a substantial temperature difference between the inside and out faces - but they seem to cope quite happily.

The problems at Kings Lynn and Kelvedon have, I believe, much more to do with some quite different fundamentals of burying steelwork in masonry.

Chris Povey

 
           
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