Sbr - Bonding

[rks]

Hello , im almost ready to lay indian sandstone riven calibrated /bronte.
My question is does everyone use sbr /cement to form a slurry as bonding agent ? Is it advisable to use if i'm going to use a (wet sand/cement ) Has anyone laid without using bonding agent and not had any problems of slabs not adhering ?
thanks for any tips /guides

[rks]

sorry should have added , if its recommended to use sbr is it best to mix with the mortar or apply as slurry to underside of flags please ,? thanks

[lutonlagerlout]

at the risk of getting shot down for 15 years i used PVA in the mortar mix and the last 7 have used SBR in the mix
around 100-150ml per barrowful
stick the slabs down well on a wet mix
you can walk on them the next day
LLL

[rks]

ok thanks ill add to mortar than rather than brush it on slabs ,i have read it goes off pretty quick though

[lutonlagerlout]

900 by 600s you get 1.5/2 flags per barrowful
it wont go off that quick!!
LLL

[Tony McC]

SBR-enhanced mortar will give you 20-30 mins in this weather. Don't be tempted to wet it up once it's started to cure. Unlike 'normal' mortar, adding water once it's stiffened up will weaken then SBR bonds.

That's why, in this sort of weather, I'd go with standard/normal mortar and rely on a daubed-on SBR/cement primer to the underside of the flags.