We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Andy Luckman (AJL Electronics)"
saying something like:

I have half a bag od mortar which has been lying around for a few years. I
needed to use some so made it up and got it used quickly, just in time to
see it go off! Now I know that old mixes do go off like a shot, but assuming
the mix is still soft when used, is the strength compromised?

And how. I made the mistake of using some old cement in a non-important
wall-chase filling. When it had dried out, it just crumbled away like
sand. Utterly useless.