Castacrete paving slabs not sticking - Paving slab problem

[Fabby]

Hi
I have laid many patios over the years and never have I come across this problem. Can anyone else tell me if they have had anything similar happen to them.

I have laid a patio using Castacrete Autumn Gold paving slabs the slabs were laid over an existing concrete base and also on some new steps that I have also built.

Once the patio had been laid and pointed the customer contacted me to say some of the paving slabs seemed to be rocking or loose. Upon our inspection every single paving slab was loose and hadn't stuck at all. I initially bedded them on a 5:1 mix of soft sand and cement.

We spoke to Castacretes rep on the phone explained how the patio was laid and he said everything I had done was fine and couldn't see why they hadn't adhered to the mortar.

I then went ahead lifted the patio up again and relaid it at my own expense this time I used 4:1:1 mix of soft sand, sharp sand and cement mix. As I was pointing the patio for a second time I noticed a lot of the slabs had a hollow sound to them again. Once again the paving slabs hadn't adhered to the mortar.

Please note that all the paving slabs were laid on a full bed of mortar around the outside perimeter of each paving slab and intermitent blobs of mortar in the middle depending on the size of the slab. Once the slab is tapped down into position a large area of the underside of the slab is covered and supported by the mortar bed.

Also the pointing had not adhered to the sides of the paving slabs there was hardly any cement residue left on the slabs at all. You could almost put them back on the shelf and sell them again as new slabs. The mortar had stuck to the concrete sub base ok but not to the actual paving slab.

Can anyone else please advise me if they have had the same sort of issues with castacrete paving slabs.

[Carberry]

Only time I know of that happening is on hot days when the mortar dries out too quickly, but I only ever saw that happening to DIYers in Australia. I'm going to guess the concrete below took all the moisture out of the mortar.

Why did you add the sharp sand to the mortar on your second attempt?

[lutonlagerlout]

is this a wind up?
rule 1 of paving is never lay slabs on dots and dabs
I dont care how much it may or may not spread out its a bodge

soft sand mortar?
another fail

mortar not adhered ,good because now you have the chance to do it right

if you have to lay over concrete assuming the concret is sound and you still have 150 mm below dpc to your finish ,then prime the concrete with sbr,prime the bottom of the slabs witha cement sbr slurry
and finally put sbr in the mix
s*&t to a blanket
also you should be using flooring/grit sand and cement 5:1

sorry for the harsh words but i lost out on a patio recently to someone with your technique
i saw the prospect ive client the other day and to quote
" he seemed to get the hang of it as he went"
"he said i didnt need hardcore"
"theres only 4-5 rockers"
LLL

[jonnyboyentire]

I'm with LLL on this one to be honest, had a similar job lost last week myself.

[London Stone Paving]

I then went ahead lifted the patio up again and relaid it at my own expense

I feel for you mate. You are willing to put it at right at your own cost which is a lot more than can be said for some of the disreputable companies out there.

Also there are so many different opinions and views about installation methods floating around, its not funny.

I learned to Pave (or how not to pave in this case) at Hills Landscapes. Hills were the most prestigous residential landscape design company in SOT (not saying that much I know ) and all the lads there were laying on the 5 dabs method. It was only when I worked for a different firm that I was shown how to lay on the full bed method.

The dabs method is a complete fail, guaranteed. The full bed of mortar method as well as being right, is also much quicker to lay as long as your getting fed by a decent labourer.

All the advice and pointers you need are available on this site. Once you've used the full bed mate, you'll never look back

[DNgroundworks]

yep i to have lost a few jobs to other contractors inferior standards

[GB_Groundworks]

It's seems it only the real pros or ppl who read here or work of specified jobs that know the full bed is correct. With ground force and bq and old boys I've been around 50 years spot bedding etc that propagate that fail method. I know builders and landscapers that do it and have fully explained it to them why not to and they don't change their method.they think it's only paving......

As for the op, I'd be relaying them right with an sir mix and sir slurry on a dampened concrete base as LLL advised you. And before that crack a beer or cuppa and spend a few hours reading the main site it's a wealth of information.

[seanandruby]

Wonder if his partner is called nicey ??? :laugh:

[London Stone Paving]

It's seems it only the real pros or ppl who read here or work of specified jobs that know the full bed is correct. With ground force and bq and old boys I've been around 50 years spot bedding etc that propagate that fail method.

Exactly. B&Q and Marshalls show videos of how to lay paving using the spot method.

You follow the methods of the people who taught you and if that person is showing you the wrong methods then your a bit screwed from the very begining.

The industry needs benchmarks and qualifications to teach people how to do things properly from the very start. Will lead to less cowboys and pobarbly bump up wages for the industry.