I just finished laying a 48 by 24 inch flagstone step. The base is 4
inches of quikrete over 8 inches of fine compacted stone. We let the
quikrete cement cure 48 hours. The weather was/is 90 degrees,95%
humidity with frequent showers. The showers happened 8 hours after the
initial set. We then layed flagstone in a 1/2 inch layer of quikrete
mortar over the concrete base, waited four hours and filled the joints
smooth with more mortar. The mortar is probably one inch thick in some
places under the flagstones because they were very uneven on the
bottom side. The flagstone was called green river or mountain green -
a gneiss/schist, very hard to lay due to beveled edges ect. My
question is this -How long do we let the mortar and concrete cure
before it is safe to use the step? When do we seal it? This is the end
of a 22 foot long flagstone (same stone) walk set over 8 inches of
crushed compacted stone and finished with the dry mortar method. We
would like to seal all at the same time if possible. The walk was
finished one week ago under the same awful 90 degree 95% humidity
conditions.  Tired, but proud - Mary Visco Holland, Ohio Zone 5