Mixing screed

[dougie120283]

hi all, perhaps one for the plasterers forum but thought i'd try here first.

I'm going to be screeding a garage floor at the weekend (no longer used for car and being turned to a utility room). i have all the gear and intend to mix a 4:1 mix with SBR and bond it to the existing concrete floor with an SBR slurry.
I've done plenty of leveling of sub-bases for under block paving using screed rails so i'm happy with that side of things (plus its not vital that its bang on level.)
my queries relates to the actual mixing. i have a standard cement mixer as can borrow one for free and would rather not go to the expense of hiring a forced action mixer. will this be ok?

also presuming a standard mixer is ok what order do i put the ingredients into the mixer?

any help would be gratefully received (plus any other tips ore useful points

 

[noseall]

Standard (Belle) will be fine.

Mixing is tricky. You only need enough water to make the stuff bind together, i.e when squeezed in your hand it should just hold together.

Getting the cement powder to mix evenly into such a dry mix is the art. The trick is to add the cement early on whilst there is still a lot of water present.

Don't try and do big mixes. Don't allow the mix to start 'balling' up.

 

[clive12345]

Hello
Firstly make sure the floor is as dust free as possible.
Next check for the suction of the concrete,by pouring half a
bucket of water on it.
Leave it ten minutes, if it sucks in, tip another bucket of water over
the whole area and brush it in. You are looking for the floor to be damp
after about 30 minutes ,not bone dry ,or running with water.
This could all be done while you are setting up.
Next knock up a mix ,tip a bucket of water on the floor (or less depending on suction) ,tip the neat sbr all over the floor.
Brush it in , then sprinkle 2-3 shovels of screed all over the floor and
brush it in . You could use neat cement instead of screed for the grouting.
You do not want the grouting to dry out , so spread two or three barrows
of screed all over the floor.
These 2-3 barrows are a good time to experiment with your mix.
As you start loading out the floor for your screeds ,if you get a wet mix,
tip it next to a dry one and mix them .

I would not use sbr in the mix ,as long as you have a depth of 2 inches you
do not need it .It makes the screed very difficult to lay and even harder to mix .
As to mixing , it depends on how wet the sand is ,try this ,
Assume total water is three quarters of a bucket .
Pour in half a bucket of water ,
add 7 sand,
half bag of cement
add 3 sand
half shovel of cement
rest of water
That should give you a good wheelbarrow full .
The mixing time once everything is in , is only about 30 seconds .
Do not forget , garages are normally 3-4 inches deeper at the front.