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RE: Concrete in extremely cold conditions

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Sub zero exposure is significantly different than cryogenic exposure. The concrete mix is only part of the issue when it comes to exposure to LOX or LNG. The IGT-PCA performed tests on cryogenic effects in the 1960's. Compressive strength was highly variable at crogenic temperatures. Samples showed little effect to freeze-thaw if they had 5% to 8% entrained air.

In general when designing concrete, you have to consider indigenous materials. This gets particularly challenging when trying to determine cryogenic performance for indigenous concrete components, and requires a lot of experience. Aggregates and cements vary significantly throughout the US. How they work in a cement matrix in a cryogenic application is highly variable.

One big problem in all concrete is the thermal gradient. For that reason I would not expose a "mat" to cryogenic fluids. The thicker the concrete the lager the gradient.

LNG tanks often have a 9% nickel plate over concrete over insulation before you get to the foundation mat which is often heated. You will need to use cryogenic rebar as a minimum.

If you do not have significant experience in designing these systems, hire a consultant. Consider Steve Meyer at Tank Industry Consultants, (317) 271-3100 or Nick Legatos at Preload Tank (888) 773-5623.

Regards,
Harold Sprague


From: "Ken Peoples" <kspeoples(--nospam--at)lvta.net>
Reply-To: <seaint(--nospam--at)seaint.org>
To: "Seaint" <seaint(--nospam--at)seaint.org>
Subject: Concrete in extremely cold conditions
Date: Mon, 14 Jun 2004 12:44:10 -0400

I have a project involving the replacement of a deteriorated concrete mat foundation. The concrete is in quite poor condition, presumably due to prolonged exposure to extremely cold temperatures caused by continuous contact with liquid gas storage containers. I am looking for standards pertaining to the recommended mix design, typical reinforcement, placement, finishing, etc. of concrete that will be used in these sub-zero conditions and would appreciate any assistance that you may provide in this area. I don't know the exact temperatures yet, but will be getting them shortly.
 Thank you in advance.



Kenneth S. Peoples, P. E.
Lehigh Valley Technical Associates, Inc.
1584 Weaversville Road
Northampton, PA 18067-9039
Phone: (610) 262-6345
Fax: (610) 262-8188
e-mail: kpeoples(--nospam--at)lvta.net


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