Environment & Energy
In reply to the discussion: First Energy Davis Besse nuclear: cracks in the containment vessel to go with corrosion in the head [View all]PamW
(1,825 posts)hairline crack in millions of pounds of concrete...
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It also shows a lack of engineering knowledge.
Concrete is very good for compression loads; but actually poor for tensile loads.
Engineers know this; which is why they use a matrix of "rebar" in the concrete.
It's actually the rebar that handles the tensile loads. The rebar also pre-stresses the concrete so that it is always in compression. When a tensile load is applied, it really just lessens the compression forces, but the concrete stays in compression.
That's why the cracks are not important. The concrete isn't being relied on to hold tensile loads in which the crack would be important. The rebar is doing that job. The concrete is being relied on for compressive loads. However, if the concrete is being compressed, then that crack is being compressed out of existence. When the left side of the crack touches the right side of the crack, then compression forces can be transferred across the crack. It doesn't matter that the two sides don't have adhesion. That would only be required for tensile loads; but we don't rely on concrete for the tensile loads anyway.
It's making a mountain out of a molehill when someone doesn't understand what material is supporting which loads.
PamW