When you load a concrete block at points "v" in this diagram, the
underside (points a & b) are in tension. Sprong goes the block, down
goes the car.
v v
|--------------|-------------|
| a | b |
| | |
|--------------|-------------|
At 10:19 AM 1/11/2010, Dan Dwelley wrote:
>"Concrete is very weak in tension" Um...the load would be
>compression not tension. and concrete blocks generally are about 15
>PSI compression.. (This is not to say they should be used as jack
>stands...cracks and damage can cause week spots and when concrete
>fails under load, it's not graceful!) The face of the block has a
>center supporting perpendicular.... it is weaker than the adjacent
>face but ... Just palying devil's advocate... :o) Dan ----- Original
>Message ---- From: David Ramsey <dwramsey@att.net> To: Tim Collins
><thcollin@mtu.edu> Cc: spridgets@autox.team.net Sent: Sun, January
>10, 2010 4:55:51 PM Subject: Re: [Spridgets] Jackstands Who cares by
>the time the cinder blocks fail, you're down the road with your new
>set of wheels and tires. Crash Finally, don't ever use a
>concrete block as a jack stand. Concrete is very weak in tension and
>will fail suddenly under a relatively small load. When loaded on the
>face of the block the concrete is in tension. Tim Collins
>http://www.flickr.com/photos/12702006@N07/
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Tim Collins
http://www.flickr.com/photos/12702006@N07/
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