Can SBR be used when no longer tacky?

[laurence peddle]

Hi everyone,
I'm using SBR/cement paste in joints between the slabs of a new patio. I paint it in and then fill the joint with 3:1 mortar. But by the time I've done a few slabs the paste has gone hard in the joints still to be done. I fill them anyway and hope for the best. Sometimes I don't fill them until the next day. Is the SBR still effective in these cases? The reason I don't mix the SBR into the mortar water, by the way, is that I've read that the mortar sets very quickly. But I'm a slow worker. Thanks in advance for any comments.
Laurence withau.

 

[noseall]

Why on earth are you using SBR to point slabs?

 

[laurence peddle]

Hi Noseall, The bonding agent helps the jointing mix to set hard and to last for a long time without cracking or loosening. The problem is that if the SBR is added to the water part of the mix, the mix goes off very quickly. But if the SBR is mixed with cement into a paste, which is then painted into the joints between the slabs, again it goes off very quickly. My guess is that it still works even when no longer tacky, but I'm not sure. Thanks for your reply.

 

[noseall]

Hi Noseall, The bonding agent helps the jointing mix to set hard and to last for a long time without cracking or loosening

So does having slabs laid by someone who knows what they are doing rather than taking advice from poorly informed television DIY shows.

I have seen used recently the granular compound type joint filler on some granite cobbles I laid on a friends drive. I have to say I am mightily impressed. Another builder friend is also using it to (retrospectively) point slabs, as he lays his then points them separately.
We point as we go. We use the bedding material to form a joint then point it with a jointing iron once the slab bedding material will support your weight - which it will do if you solid bed the slabs rather than spot bed them.