huangyhg

min temp for concrete
hi,
is there any document or code which talks about the minimum temperature resisted by the concrete of different grades. we are using this concretre (cube strength 40n/mm2) for cryogenic spillage and to design the insulation for the same i need minimum temp which can be sustained by this concrete.
thanks in advance.
i didnt know there was a minimum temparature if it is cured already. i am watching this post.
years ago, in southern california, i worked in the aerospace program. our company used a great deal of cryogenic materials (mainly hydrogen, lox and even played with flox) in addition to liquid hydrogen and petroleum compounds. much of the structures were stainless and all our gratings and supports were stainless because they also supported the piping. i appreciate your situation.
all finished ground cover was concrete since asphalt was too good of a fuel. we were concerned about the concrete life since some splls occured around the tanks. there was no corporate or government money for a quick answer, so we conducted some non-scientific testing/observations - impact, chipping after repeated exposure. we did not have any numbers.
it appeared that higher strength air entrained concrete held up better, probably due to the entrained air voids, just as it does for freeze-thaw resistance.
based on some other things i have seen in some russian durability testing, i would suspect that lightweight concrete made with quality lightweight aggregate (not natural pumice, scoria, etc.) could offer some advantages because of the void structure. manufactured rotary kiln expanded shale or clay (uncrushed in all sizes if possible) would be a good starting point. this also offers additional insulation compared to convential heavyweight concrete.
the lightweight aggregate producers may have some information on the subject. google gravelite, arkalite and livlite for possible information sources. the guru of the industry was a brilliant man, thomas (tom) holm, who authored many very technical astm, aci, etc. papers on the structural and other uses of lightweight aggregate. he has retired, but some of his information should be available.
i hope this helps you on your quest in this narrow application of concrete.
dick
concrete masonry is on the money with pointing you towards lightweight aggregate, although there are other options.
what duration and frequency of exposure are you looking at? you can approach things differently for spills or storage.
hi,
actually this is a lng inpoundung basin. so if there is any leak from the valves or from the tank itself, it will routed to this basin. to insulate it from the -160deg lng we asked the foamglass supplier to gives us the required thickness of foamglass but in his response he is asking about the minimum temp which this concrete can resist. then only he would be able to tell us the thickness of the insulation required.
any thoughts on this ?
cryogenic temperatures aren't a huge drama, assuming sensible mix designs and reinforcing choice. the problem is with differential temperatures and rate of temperature drop. a rapidly cooled surface and comparatively warm slab interior (e.g. a spill) will behave as you'd expect, cracking and spalling progressively through the slab. you can see why air-entrained, higher-strength concrete helps.
more information tends to overlap with how i pay the bills.
thanks all of you for the info. i think i would still go for foamglass insulation of 150 thk as i would keep concrete temp above -10deg for 2.5hrs as specified by hse.
if you want to check a little further in to the properties of concrete at cryogenic temperatures just enter "cryogenic" in search box.
thanks unclesyd for this link. this in fact seems to be quite useful.

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