Recently laid 'stepping stone' slabs are loose

[cdorling]

Hi

I'd be grateful for some advice, please. I embarked on a patio project that should have been finished last spring, but due to a bad back, I'm still at it! I have one main issue at the moment, any advice would be gratefully received:-

1) I am using block paving as an edge around what will be a slab patio. Some blocks will be up against a wall, others will divide the patio with a 'stepping stone' slab path. I'm doing the blocks next to the path first. I'm cementing the blocks in (3:1), and 'haunching' them as best I can. Those I've laid this week (after work each night) look pretty solid. I laid the 'stepping stone' slab path last week-end, only 7 slabs but it took all day to get them all levelled! I used 3:1 thinking this would give a better bond. Tonight I noticed that 2 are loose already, which is a great disappointment. At the moment they are sitting quite 'proud' as I planned to infill first with MOT then 50mm slate. Having cursed 100 times, I've thought of some solutions:

a) angle grind out the top bit of the cement under (? just the loose) slabs, then:-

bi) either relay the slabs (not sure on the mix, though), and haunch (am I using the right word?) with 3:1 cement or concrete, either at an angle up to the edge of the slab so that the cement/concrete won't be seen (but it won't give much support around the slab), or else haunch it so that there's a 2-3 cm sort of frame or joint all around the slab. Then infill with the MOT/slate as planned. Would doing this stop them coming loose in future?

bii) change my plan and reluctantly cement in all around the slabs, almost to the top edge of the slabs, pushing teh slate into the cement, pebble dash style. I don't think that will look very nice, but thats the best I can come up with.

Hope you've understood, and can help me out, as I'm surethere's a way to do this properly. Thanks for reading, Chris

[lutonlagerlout]

chris if they are loose already they werent laid right. mate.
full spec for laying slabs is on the main site but for stepping stones i would go for a wet 6:1 mix with some ronafix or pva in it
cheers LLL

[cdorling]

Thanks, LLL. I used a fairly dry mix, no wonder I've had jip. I've got some pva, so I'll try that method out on one loose slab today, plus I'll 'paint' the bottom of the slab with pva as well (2 pva : 1 water?) and use a wet 6:1.

Would that be enough to hold the slab, or should I still try & give it some cement support around the sides as well?

Would it be best to redo the non loose ones, to save problems later?

[Rich H]

Should hold just fine. You shouldn't need to paint the slab if you're using a wet mix. With a dry and very strong mix as you used before it's possible that the cement and sand dried out before the cement cured which would prevent the slabs from bonding.

[cdorling]

All the slabs are loose, so I've hacked off some cement from the 1st, hope 20mm is enough. I've added 'a dollop' of pva to the cement + painted a bit on the back of the slab + haunched it too ( for good measure).

It's taken me ages to chip off the old cement off of just one, is there a 'glue' that I can cheat with and just add to whats already there?

[Rich H]

Not really, I'm afraid.