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Posted: Tue May 24, 2016 11:10 pm
by rks
Please could you advise , my drain is sited against the house , so could i have the 1:80 gradient towards the house when laying riven slabs if im fitting a drain channel against the house ? also how much water is reccommended if using a 10:1 mixture of sharp sand / cement ?
thanks for any advice .
Posted: Wed May 25, 2016 7:29 am
by lemoncurd1702
It say's 1:80 Here if that's where you found the info.
It's fairly tight if using riven, particularly if they are roughly hewn. If it's a short run it shouldn't cause any problems though.
Hard to give a measure of water because the sand can have varying degrees of moisture. Chuck 1/4 bucket then about half you mix then add more if needed and chuck in rest of mix.
Also depends on whether using a wet or dry mix. If wet chuck a splash of plasticiser in also to get a nice flexible mix.
10:1 would be a bit lean for me. Most on here go for 8:1, but personally I prefer a bit stronger than that.
Posted: Wed May 25, 2016 9:37 pm
by rks
ok thanks and should i add plastisicer or sbr ?
Posted: Wed May 25, 2016 10:15 pm
by lemoncurd1702
Some do, I don't see the need. Maybe good to use sbr mixed with cement to make a paste and paint on bottom side of slabs.
This will help it to adhere to the mortar bed. A must if using a semi dry mix.
Don't worry about covering all of the bottom of the slab but don't get any on the surface, wash off quickly if you do!
Posted: Thu May 26, 2016 9:58 pm
by lutonlagerlout
i add around 100ml of SBR to every gauge,with a wet mix never used a bond bridge and never had any problems
LLL 