--- Ruth Barton <[log in to unmask]> wrote:
> It looks to me as though lime is leaching out of the
> cement and oozing out
> of the cracks in the cement.  I would think this
> would weaken the cement
> and hasten the wall's demise.

Ruth

I suspect you're seeing a very hard whitish crust
forming in rundown patterns below the cracks.  If you
try to remove it, you will find it very difficult to
do so.

This is often called 'lime staining', but it is not
really lime.  It is calcium carbonate (with other
things in it too).  It is formed by water passing
through the wall and dissolving soluble portions of
the cement, which are then deposited as calcium
carbonate when the water gets out into the atmosphere
again.

This is very common on areas of paving that are not
properly drained (especially at stairs), and can
happen in situations like the one you describe.

Will it weaken the wall?  Yes, but only after a long
time (decades?).
Will it cause the wall to fall down?  Maybe, but it
sounds like the cracks and other disturbances are more
likely to be the biggest problem.

What to do about it?  Reconstruction sounds like it
might be in order, depending on how bad the cracks
are.

Cheers
david

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