Newly laid bluestone squares wet underneath and loose
by Craig H
Stones after they were mortared down and sponged off
I've spent the last couple months putting in a patio with the help of a family friend. We had to build a block wall, backfill, then poured a 4" slab on top. Slab cured for about 40 days. The last major step was done 2 weeks ago, when we laid bluestone squares (2x2) over the slab with mortar. It seemed to go well.
I went out there today to prepare for grouting/tucking the joints, and noticed water squishing out of the edges of about half the flagstones when I walked on them (primarily the ones in the center, but also some edges). Thinking that was not good, I was able to pry a couple flagstones loose with my bare hands. The mortar bed underneath looked very continuous and was a mirror image of the bottom of the stone, so clearly we had good contact. But there was a lot of moisture under there.
Not sure if it's due to all the rain/humidity we've had, or maybe it was a mistake to try and cover the stones with a tarp when it rained, possibly trapping moisture?
Anyhow, now I am wondering how to salvage this mess. Lots of time/labor, and of course the flagstones weren't cheap. Anybody have ideas?
Since the mortar bed looks decent, I am really tempted to re-glue the stones down with some sort of adhesive. I am no mason, but OK with mortar/concrete. However, this experience has me feeling outgunned.