The Brew Cabin

First, Great site, very useful for my first foray into paving. Now my question: I'm part way through building a slightly raised patio, 450mm square textured flags on a 10:1 dry mix to be grouted later. They're built on one course of blocks. I've been individually bedding the flags and the dryness of my mix is rather erratic. I reckon I added water when I shouldn't :( . Problem is, some of the flags have adhered to the bed and some haven't, in particular a few that are at the edge, and overhang the bricks are loose. What did I do wrong there, and how should I fix them? In fact, should they actually have stuck down at all? I still have lots to learn, so forgive my ignorance. When it's built, may I post you some piccies?

Good one iam not the only one then ive just laid block pavers for a path.And some have stuck and some have not it say`s 10/1 for slabs.Then on the ridged section 3/1. I did about 8 to 1.A did a fairly stiff mix then tapped down with a mallet.where have i gone wrong.Have i not tapped down hard enough.cheers great site

i use 4 shovels of sharp to 2 shovels of builders and 1 shovel of OP, and make it pretty wet then i lay on 2 inches of this mortar and have never had a problem with loose slabs or edgers i find a wetter mix adheres very well and goes off in around 24-48 hrs, u can use hardener if u are in a hurry and in hot weather i use a plasticiser.

For flags/slabs, there's usually no need for the flags to adhere to the bedding. In fact, on commercial contracts, we use a lime-based mortar to ensure that any bonding will be weak and easy to break should the paving have to be lifted for whatever reason.

The only time you would definitely want the flags to bond to the bedding is where one or more edges of the flags are 'free'; that is, they are not abutting any other flag or a fixed object such as a wall or manhole cover. This can happen with a typical patio or other pavement at the edges, but, in the vast majority of jobs, there's no need to bond these edge flags to the bedding as the forces they encounter are minimal and easily contained. However, in those scenarios where the edge of the flag is exposed, or overhangs a sub-structure, such as a step, then it is a definite advantage to have the flag bonded to the bedding, purely for reasons of safety.

If a point load (ie, a person) is applied to the overhanging edge of a step, then there is a possibility that the whole flag could pivot and flick upwards. This possibility declines with larger flags, smaller overhangs and lighter point loads, but it is good practice to create a bond in these situations, just to be on the safe side.

A good bond can only be achieved between a reasonably wet/tacky bedding material. You can't get a good bond between the underside of a flag and a semi-dry or dry mix, and so a wetter mix, such as that described by Suki, would be ideal for use at the edges of pavements or when constructing steps, even though it is (in my opinion) much harder to work with elsewhere in the pavement.

So, in summary, I would only ever use a wet bedding mix for step treads and/or for pavements where there is a real chance of flags at free edges slipping out of place. Elsewhere, I'd use a semi-dry mix.

To Bry, the original poster, you're more than welcome to send in piccies of your efforts, and pass on anything you've learned from the experience.

To mrw, the second poster in this thread - I've no idea what you're on about!

Cheers Tony,
I've lifted those few flags and used a stronger wetter mix: They seem well stuck now. That said the overhang is only 1/2 an inch, so I'd probably have been ok anyway.
The project, affectionately known as "Bry's bandstand" is coming on nicely, I laid the last cut bit of flag today, and have just to add some coping to the wall, then lots of grouting. Dark nights, weather, and having a day job are all detracting, but I'll be sure to post you some pics, 'cos I'm well chuffed at my first bit of building. :)
And Yes, I've learned a few lessons, some painful, which I'll relate later.

Now I've got the bug, I can see myself ripping up all the garden and building an aerodrome. Maybe next year though for that, when I've got a new wheelbarrow.
Regards,
Bry.

If you're a good boy, Santa might bring you a new barrow. ;)