Ultimate adhesive required

[WabbitPoo]

3 years ago I was called upon to fix limestone slabs vertically on a block wall I had built for someone. The slabs are 600x300 and pretty weighty. I tried a variety of adhesives, none of which seemed to be man enough for the job.

Then I found Sikadur 33, which, while a pig to use, seems to be strong enough.

Except that a few of these slabs have come off every year (not the same ones) so now I am seeking the ultimate adhesive. I think maybe the Sika is not flexible enough so the slabs, being dark blue, probably heat up and shrink, causing a brittle bond to fail. It is worse over winter, so perhaps its the frost.

Anyway, any ideas what to try next?

Thanks

 

[freddiemercurystwin]

Stone cladding should be on metal rails not stuck on with some glue! How thick are they?

 

[catlad]

sika brought a new one out recently T2 I think, it claims to hold 250kg per 10cm2.