Limestone diy disaster.

I haven't seen the dark stains but I have seen a patio where algae had accumulated on the top of the slabs exactly where the contractor had placed the dabs - and where he hadn't! It disappeared after a pressure wash though.

 

If the hardcore or actual ground is good, there's no need for cement. We lay these on a bed of compacted sand, brutal truth that first pic shows one laid on a stone nearby. the line is too low and not wide enough.

 

I'll put my pennyworth in! I've laid loads of the India stone flags on three big projects and simply mixed a wetish mix - about 1:5 - nothing special and put them down on very well compacted ground underneath - honest! Used the handle of a club hammer (gently), jumped on them, slide them around to settle them and allowed the compo to extrude up the gaps - let it go off a bit (DONT play with it otherwise you will stain the surface) strike off the joints and keep the pet elephants off till its gone off. Tried to remove 7 flags months later to lay some MDPE and couldn't lift them without breaking them - so I gave up on the MDPE. They are still stuck down and wont shift. So there you go! Have fun!

 

Think I'm going to sort out one loose slab, it was the first one nearest to the front door and wasn't SBR'ed.

Think I will stixall it down

 

Excellent!

 

Sharp sand or building sand ? Regards david

 

I'd be tempted to lift the lime stone off, brush then hoover and apply this gear as a 1mm film over the surface and set the slab back down.

It's seriously strong, cures to 70 Newton and could be used to bond those Slabs to a wall never mid a path

http://www.epms-supplies.co.uk/p-Sikadur-31-CF-Normal-(274).aspx

 

Hello I’m a bit late to this sorry ! I’ve been laying paving for well over 30 years now and I can tell you all is not lost hopefully. Some of the earlier replies about SBR are correct but this way will allow you to relay on your existing sand and cement base with just a 2mm height gain but you will need a paddle whisk to achieve this. Lift the loose slabs up and using a slurry with SBR cement and water to make a very runny consistency you can pours out, a bit like single cream.Pour it over the existing mortar base but make sure you completely wet the base first and the back of the slab otherwise the slurry will set to quickly. Pour just enough slurry out to cover the base spread with a trowel to cover the base then lay the slab, do don’t bang it just wiggle it into position. This I guarantee will never go anywhere.

 

Sorry two things to add to that make sure the base and back of the slab have no existing mortar or debris on them and mix 1 part SBR to 2 parts water then keep adding cement till pourable consistency.

 

a bit late indeed, 7 years......