On 1/21/2012 2:10 PM, wrote:
Okay, it's he
http://www.brainchampagne.com/Comedy/tempphoto.jpg

The new cement is on the top of the photo, below the drain, then the
brown line, then the old cement.

Looks like either dirt or perhaps some iron or other soluble
contamination was in the region at the edge and got floated to the top...

It's not owing simply to moisture/water; the color is not that of the
concrete/cement (as you're aware and why you're asking).

However, it's highly unlikely that it's going to do any harm and while
somewhat visually distracting I doubt you'll have any luck at all
getting the guy to break it out and redo it (at least w/o paying him for
the labor) as I don't think it is serious enough of a defect to justify
or be able to win if you have to try to force the issue.

You might wait a while 'til it finishes curing then try a little etching
and see if it is only a very thin surface layer if you'd like to
minimize the color difference. A sweeping of just plain portland cement
over the top w/ a little damp could also help camouflage it as well
simply like face powder to fill in the tiny pores a little w/ some
lighter-colored material.

All in all, I'd not worry about it.

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