Sbr advice

[Janavi]

Looking for some advice on SBR please....

I'm laying a sandstone patio next week and intend to seal the underside of the paving. If I apply SBR to the underside of each slab just before laying, that will seal it preventing efflorescence and also increase adhesion, is that right?

Can I/ should I ALSO mix SBR in with the bedding mix to increase its strength?

Cheers,
Jamie

[digerjones]

Mix sbr with cement into slurry to coat the back of slabs just before you lay them. You canput it in bedding layer but not sure if it makes any difference. Make sure you clean any spills of sbr with clean water

[Tony McC]

Using SBR, either as a primer or in the bedding mix, will do precious little about efflorescence. A properly prepared primer slurry (SBR plus cement works adequately) will help minimise the risk of eff, but nothing can guarantee to "prevent" it happening.

The good news is that this is the low season for eff problems. Warner temps and allegedly drier days (it's persisting down outside as I type this!) all help keep it to a minimum, but, even so, there is always a risk it may show up.

Having said all that, SBR most assuredly *will* improve adhesion, but, to be honest, adhesion is not usually a problem with sandstone flags when laid on a moist or wet-mix mortar.