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Re: Large block of concrete

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Rajendran,

You might want to take a look at ACI 207.1R-96 (Mass Concrete) and the
other documents produced by ACI committee 207, such as ACI 207.2R-95
(Effect of Restraint, Volume Change, and Reinforcement on Cracking of Mass
Concrete), ACI 207.3R-94 (Practices for Evaluation of Concrete in Existing
Massive Structures for Service Conditions), and ACI 207.4R-93 (Colling and
Insulating Systems for Mass Concrete).  I honestly don't know how good the
documents are, but they should have some good information in them even if
they are not the best documents in the world.

HTH,

Scott
Ypsilanti, MI


On Sat, 19 Jul 2003, Padmanabhan Rajendran wrote:

> Harold, the concrete guru:
>
> In the refinery and pipeline industries, often a large concrete block is provided to support equipment such as a pump or a compressor skid.
>
> Let us say that one such block is 16' wide X 50' long X 8' deep. I believe that the heat of hydration will be pretty large and the thermal gradient may take years to get dissipated.  Thermal gradient would cause microscopic cracks throughout the concrete. I have not seen any special requirement called out in a typical concrete specification or in the notes on the drawing. What are your thoughts? Should low heat cement be used? If ues, what are the implications? Is there any other strategy to lower thermal gradient? Staged construction may not be acceptable because these clients are typically in a great hurry!
>
> I have come across thousands of dollars spent in repairing old concrete block foundations for compressors. Papers that have been published by agencies recommending and/or performing such repairs point out that the concrete damage arose from the machine vibration. I wonder if the problem was initiated by the microscopic cracks from thermal gradients and susequently, machine vibration took advantage of the weakened concrete.
>
> Thanks.
>
> Rajendran
>
>
>
>
> ---------------------------------
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