Blown pavers - how to resolve?

[Bitpipe]

My landscaper laid 600x900 pavers for our patio on a SBR sand & cement mix. They were very smooth on both sides and only 25mm thick.

 

We were planning on using easy joint for the pointing but were worried about water ingress (it's porus) so I started pointing with BAL exterior grout but didn't get the job finished before it got too cold & wet.

 

Now that we've had a hard frost, a few of the pavers in the un-grouted section have blown and lost their bond with the underlying base - as they're quite heavy they're not moving but a few smaller sections are so I want to bond them back in place before grouting this area when the weather improves in the next weeks.

 

First idea is to cut back some of the sand & cement and use exterior tile adhesive - we have to finish the concrete basement stairwell in the same stone and would be using adhesive for that.

 

Wondering though if there is any alternative method that would work, i.e. some other kind of pre-mixed adhesive?

 

Landscaper has also offered to cut out the grout that I've put in and use easy joint, and then seal the whole patio but I'm not sure on that approach.