Replacing a couple of damaged patio slabs today, laid on a sand bed (I'm guessing 10-1 with cement).
I don't do a lot with mortar. I assumed a fairly dry mix would be best, helping to take the weight of the slab. Wrong!
The sand & slab seemed to suck the moisture out, so tapping the slab level & flush was almost impossible.
A fairly sloppy mix did the trick OK.
Is this what a mortar plasticiser is for? Would that have kept the moisture in the mortar? If not, what does a plasticiser do?
What did you use to get the flags down? - if you use a flagging mallet (3ft handle with a huge rubber block at the end, about 4 inch diameter and 10 inches long) then it only takes a few taps to go down
sloppy is fine, providing no one walks on it for the next 24-48 hours...unless you use a strong mix - failing that, you should have mixed dry cement in with the sand bed and bedded it down on that, although without a mallet, you would have to be almost spot on with the bed - a mallet would take it down up to half an inch
it stops the water seperating from the mortar
I'm not surprised :-) No, just a small rubber mallet like you buy for tent pegs.
No one will walk on it for at least 24 hours if that. Could you define strong mix please? I used Hanson ready mix mortar from B&Q.
The bed was a mixture of cement & sand judging by the colour & firmness.
Wow! I'm amazed! Mind you, that is some kinda mallet.
Oh OK. So would it stop a porous bedding layer & slab taking the moisture out?
In message , The Medway Handyman writes
Dry mix, not fairly dry, no added water. Any moisture already in the sand is usually enough - and sharp, not soft sand.
What depth did you scrape out to before replacing the bed? if you went with a 10mm bed then you're unlikely to get much 'squeeze' out of it :-) I recently laid a garden path on 50mm 9:1 dry and had no problems tapping flush 5 mm or so.
No, it improves the workability of the mortar for a lower water content, end result being a nicer mortar to work with and stronger final set.
Hth Someone
They are fine for replacing the odd block pavior
I've never used anything like that so I've no idea what strength it is, cement is £3 a bag and sand £1.20, the former has a 'life of around six weeks in dry conditions, the latter a few million years :-p
Strong is 3 or 4 to 1, normal is 5, 6 or 7 to 1 and weak is 8:1 and above...readymixed is probably 4:1 I should imagine given that it could be used for almost anything.
If the bed was already solid or semi-solid, it needed to be hollowed out so as to take some fresh mortar.
Not really, mortar with or without plasticiser will dry out fairly quickly, plasticiser just keeps it workable for longer - once it's in place, IE between bricks or for pointing up holes, both would 'go off' at practically the same rate
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