Hi there, Can somebody please help me with my patio laying. I laid a few rows of slabs last week on a 2.5" wet mortar bed of 3 sharp sand to 1 cement with a plasticiser on a 4" MOT whackered base. It did rain 24 hours later but I did cover them up. I went to lay some more yesterday and realised that they were loose and not adhered to the slab at all, not one bit of cement had stuck to the slab and there was complete contact with no voids. I have bradstone ashbourne slabs and the only thing I did notice was that there is a shiny "film" on the back of them. The cement didn't really take to the hardcore that well either. I've got them all back up and am ready to start again but not sure what to do, should I add a hardener to they go off quicker, even though this doesn't really help with the adhesive side of things?? Any help would be gratefully appreciated.
Why on earth would you use sharp sand? Building sand should be used. No need for plasticiser either. Also 6:1 is a much better ratio.
Also forgot to say that some local builder told me to use 3 sharp, 2 building to 1 cement...I really don't know what to do for the best...??
Building sand on its own is to soft and mixed at 6 to 1 is useless below ground, it will fail. Use a plastering sand or as your local builder said 3 sharp and 2 building, wet mix and full bed of mortar.
Hi Melly I laid a patio last summer with a friend and being a diy'er, did a fair bit of research before we started. Found a brilliant site with endless info on all aspects of paving - pavingexpert.com (It's been recomended on this site many times) Not knocking any help that you may recieve on this splendid site but really suggest that you spend some time reading through pavingexpert and you can post questions as well I laid my slabs (after ground work prep) on a solid mortar bed of sharp sand / cement @ 6-1 with a bit of plasticiser in the mix There is a lot written on paving forums about slabs not bonding with the mortar bed and a lot of replies say that this is quite usual and not a problem, as long as you leave a gap between the slabs and then fill with mortar, this will then bond the slabs together Wanted my slabs to stick to the mortar bed (just seems a better job to me) so "painted" the back of each slab just prior to laying with a slurry mix of SBR and cement powder - they stuck like sh#t to a blanket and not a single rocker Then filled the joints, spaced at 10 mm, with a damp mix and the slabs will never move Hope you find this helpful and read up on the above site - good luck