On Fri, 6 Feb 2009 17:51:46 -0800 (PST), Justme
wrote:

I live in a house with cement rock as decoration on part of an outside
wall and inside around a fireplace.
Recently a patch of the 'rock' and mortar both outside and inside have
falling off. I can see a metal mess below and cement/mortar.

How do I stick the big pieces back onto these fake rock walls?
The areas to patch are small and I have the chunks that fell off.

Thanks so much.

Add lime to the mix. Faux stones hold-up on ceilings this way.

Lime may add tack in the mortar.