Bridge bond on black limestone

[exoticpete]

Hi all laying a black limestone patio this week thinking about cement/SBR slurry on the rear face does it need it ? Just aware that if we get any staining its a bugger to get off, know about not using acid
Many thanks Peter

[lutonlagerlout]

dunno about other but i put around 100ml of SBR in the wet mix
always have a bucket of CLEAN water nearby and a sponge
cheers LLL

[Tony McC]

It doesn't really need it, as long as you have a good mortar bed, moist mix (or wet mix, if you must), and the flags are not too dusty.

A bond bridge is an insurance policy with black limestone: it ensures they stay put, but for some pale flagstones such as some granites and lighter limestones, it can also help minimise 'wicking' of moisture to the surface which is rarely, if ever, a problem with black limestone.

[exoticpete]

Thanks gents think we will just put some SBR into the mix
Peter

[mark_buildnrepair]

Hi.

100ml of SBR in the mix will make it smell nice, give it that unique-SBR blueish tinge and give some plasticiser effect.

For full benefit use 1:1 SBR : water in the mix.

If you want a bonding bridge/bonding primer as well, it's 1:1 SBR : cement.

Our website carries Ronafix and our own brand BnR SBR

[cookiewales]

Hi.

100ml of SBR in the mix will make it smell nice, give it that unique-SBR blueish tinge and give some plasticiser effect.

For full benefit use 1:1 SBR : water in the mix.

If you want a bonding bridge/bonding primer as well, it's 1:1 SBR : cement.

Our website carries Ronafix and our own brand BnR SBR

over kill on sbr good glug per mix is ample ie belle mixer half cup big mixer cup full i remember buying 25 litres for the price of your 5 litre 1987 :p

[lutonlagerlout]

I agree cookie
mark we are the guys on the front line so to speak
and after doing many patios 100ml in roughly 5 litres of water definitely adds strength and works long term

1:1 I would only contemplate for pier copings or ridges tiles
LLL

[Tony McC]

Mmmm...the different attitudes of contractors looking for maximum value at minimum cost and retailers looking for maximum sales volumes.

Still, 1:1 is seriously beefy. Fine for a bond on commercial projects with vehicle overrun but definitely OTT for patuos type projects, and that's the opinion of someone who neither buys it nor sells it!

[mark_buildnrepair]

I guess we all have our own experiences - and responsibilities.

Ours is to give advice based on proven lab and field results.

If your own experience shows that diluting a manufacturers' technical recommendation will still achieve the required result, then I respect that. And that is your responsibility should something go wrong.

Manufacturers and technical advice departments need to ensure that what we recommend will work in most circumstances, given the huge variation in raw materials, gauging site batched mixes, techniques, substrates, weather, mixing methods, etc.

[lutonlagerlout]

mark if i use SBR my way it adds £40 to the cost of a normal 40Mpatio

for years we never used it all but most here found that indian stone tends not to stick well

doing it your way would cost £400 which in most cases would cost half as much as the flags

not many will wear that mate

LLL

[Tony McC]

Manufacturers and technical advice departments need to ensure that what we recommend will work in most circumstances

....which is fair enough, but then there is an overwhelming tendency for the supply-chain to err very much on the side of caution and build-in a factor or safety, whereas contractors are more at ease working 'on the edge'.

Few, if any, of us would skimp on a critical project, but when it's a basic patio....well, we tend to rely on experience.