Quick Screed Q's

[neds]

I've laid a small area of concrete down and will need screeding. The mix I will use is 3 sharp sand to 1 Cement. I hear the consistency is a bit tricky to get right, any tips, also is there a reason why it has to be so dry? Sounds like a b*gger to lay flat if its dry!

Also anything I can use to bond the concrete to the screed? Possibly a wet mix of cement/sand to give a good key? The screed will about 3/4" thick.

Cheers!

 

[chessspy]

Hi, Neds,
That sounds a bit thin for a dry screed it's normally about 50mm.
And it's usually drylean mix 10-1 or so.
As yours is so thin, you might try laying it wet and strong, but not more than 5 or 6-1, (however on second thoughts it might contract on drying and crack)
For bonding use a proprietary bonding agent like PVA Read the label.
You could try self levelling compound, but it sounds a bit think for that, (normally 3-10mm)
you could try granite chippings mixed like concrete, that will be strong and will screed at that thickness. get the smallest size chips obviously.

 

[neds]

Hmmm OK cheers for that, Well the screed will probably be be a max of about 1" as it need to be level with the rest of the concreted area. I just thought that since I had some sharp sand anyway I'd be able to do a quick screed but looks like its a bit more to it than that!

 

[roy c]

When screeding on top of concrete mix a cement water "Slurry" up and brush it on before you put the screed mix down. If you mix the 4 to1 screed up yourself in a mixer you have to be quite experienced to stop it "Balling". The mix is the right consistency when if you squeeze it in your hand and it just holds together. The least amount of water makes it a strong floor, and you don't put any additive with the mix!! There are also suppliers that will deliver it to you ready mixed, you
tell them the area you want to screed and they will work out the amount. They will also ask you if you want a retarder in it (which is advisable) and if you want "fibres put thru it( helps to hold it together!!) your choice on that..If you mix it yourself make sure you use "concreting sand,,,,,Don't put a s/c screed down less than 1 and a quarter inchs thick.....