Posted: Tue Aug 25, 2015 1:51 pm
As posted in another thread, I am a DIYer about to attempt laying some 20mm thick quartzite paving and have been reading this site and forum to establish best practice for laying them. However, it seems that there are a number of differing opinions on various aspects:
The main site suggests semi-dry as a preferred slump for a laying course, as it is cleaner to work with and has a longer working life. However, on this forum however, I have read several posts where people have followed the advice of using a semi dry mix, but have had problems with adhesion and they normally get told that they should have used a moist or a wet mix (and a bond bridge if they didn’t use one).
As for adhesion, the main site suggests that adhesion between the laying course and flags isn’t actually important, but the forums are full of people with flags that aren’t adhering being told what they did wrong.
Regarding Bond Bridges, the main pages of the site provide a recipe for a self mixed bond bridge of SBR and cement, and states that SBR costs £3-5 per litre. However, on a forum post where someone had used Cementone SBR (approx £4 per litre) to mix up a Bond Bridge, they got told that the better SBR costs £20 per litre.
After reading the above and being thoroughly confused, I decided to try laying a test flag (using a small 15x15cm sample). I used a semi dry mix and no bond bridge, to test adhesion of this paving. The bed set fine, but the flag lifted right up. So based on this I think i do need to do something different to get better adhesion.
Do you think just using a wetter mix would be enough to promote adhesion, or do I need a bond bridge? Also, given that the chap in the forum who used Cementone SBR got told that he should have used a “better� SBR, does anyone have any recommendations for a better one to use (one that is still fairly easy to source though)?
My main concern at the moment about using a bond bridge is the working life. The patio I am laying is pretty big (circa 4m x 10m) and is being layed using a random layout, and will therefore need some joint balancing. I get the impression that the bond bridge will go off pretty quickly, potentially causing me headaches when it comes to joint balancing.
Any advice (other than get a professional in!) on how to get proper adhesion but still have enough working life to do the joint balancing?
The main site suggests semi-dry as a preferred slump for a laying course, as it is cleaner to work with and has a longer working life. However, on this forum however, I have read several posts where people have followed the advice of using a semi dry mix, but have had problems with adhesion and they normally get told that they should have used a moist or a wet mix (and a bond bridge if they didn’t use one).
As for adhesion, the main site suggests that adhesion between the laying course and flags isn’t actually important, but the forums are full of people with flags that aren’t adhering being told what they did wrong.
Regarding Bond Bridges, the main pages of the site provide a recipe for a self mixed bond bridge of SBR and cement, and states that SBR costs £3-5 per litre. However, on a forum post where someone had used Cementone SBR (approx £4 per litre) to mix up a Bond Bridge, they got told that the better SBR costs £20 per litre.
After reading the above and being thoroughly confused, I decided to try laying a test flag (using a small 15x15cm sample). I used a semi dry mix and no bond bridge, to test adhesion of this paving. The bed set fine, but the flag lifted right up. So based on this I think i do need to do something different to get better adhesion.
Do you think just using a wetter mix would be enough to promote adhesion, or do I need a bond bridge? Also, given that the chap in the forum who used Cementone SBR got told that he should have used a “better� SBR, does anyone have any recommendations for a better one to use (one that is still fairly easy to source though)?
My main concern at the moment about using a bond bridge is the working life. The patio I am laying is pretty big (circa 4m x 10m) and is being layed using a random layout, and will therefore need some joint balancing. I get the impression that the bond bridge will go off pretty quickly, potentially causing me headaches when it comes to joint balancing.
Any advice (other than get a professional in!) on how to get proper adhesion but still have enough working life to do the joint balancing?
