Mixing Screed

[sotal]

I need to mix some screed up.

I've got half a big bag of sand left from when I did my patio, which I would like to use in the screed - the only problem is the sand has been outside since last summer.

The bag was folded over the sand and a couple of slabs were left on top (to stop cats more than anything!)

Anyway will the sand be too wet to use? Or will it be OK?

I was going to do a 3:1 sand to cement mix.

How wet should a screed mix be?

Also any ideas how much sand and cement I'll need? The bit to be filled it 1.5m x 1.9m x 65mm - so not very big.


And finally can you confirm that the screed can go straight on top of polystyrene insulation?

THANKS!

 

[plstering]

type 1 stone wacked then a soft sand blinding over the top wacked
the builders plastic then polystyrene insulation coverd with a concrete base
then you screed it
as for screed 4:1 mix with added PVA too the mix
if you want you can use fibers in the mix
as for the sand best way too tell is when its mixed dry dont add water yet get a hand full and squeeze it in too a bull if ih holds and is slite damp
happy days its your call as tooo how you want the mix
if its dry add water

 

[sotal]

Thanks for the reply,

I'm raising the floor, so already have a concrete base.

I was going to put DPM down first ontop of the concrete, then the polystyrene inuslation. Tape the joints then put the 65mm screed over the top.

I'll do it between 3:1 and 4:1 as I've seen both mentioned.


Any idea on how many 25kg bags of cement will be required?

 

[plstering]

i base most my mixs 4:1 6/7bags per tone m8 if that helps

 

[Alastairreid]

Thanks for the reply,
Any idea on how many 25kg bags of cement will be required?

4.

http://www.source4me.co.uk//calculate_floor_screed.htm

 

[meadowhog]

The best way I have found of describing how to get the mix right is, if you roll up a cricket ball size of screed then try to split it half like a terrys chocalote orange.

If its too wet your fingers will just dig in, if its too dry it will just crumble, if its just right it will cleanly break in half.

 

[Judderbar]

Video of screeding from start to finish with apprentice supervised by building teacher at Australian college.

Shows holding mix in hand to demonstrate correct wetness.

http://www.tilewizards.net/videos/v...ay-to-level-a-floor-with-sand-and-cement.html