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-   -   Concrete Plaster coat Mix ratio needed, for brick interior wall. (http://www.diychatroom.com/f105/concrete-plaster-coat-mix-ratio-needed-brick-interior-wall-149337/)

Spud 07-06-2012 04:17 AM

Concrete Plaster coat Mix ratio needed, for brick interior wall.
 
Non load bearing Brick interior wall that partitions off the bathroom. The cross section sides of the wall are to receive replacement door frames. The other 2 sides of the wall already retains the old cement plaster coat.

I need to apply about 0.5 inches of cement plaster coat onto the brick and remanants of the old cement plaster coat.

Questions:

What Concrete Mix ratio should I use?

Do I need to attach a metal lathe, even though I am only applying 0.5 inches thick cement plaster coat?

Can I apply the 0.5 inches as 1 coat or do I need to do 2 coats?

Can I use standard concrete mix ratio, the same used in contructing structural concrete columns?

Can I use Oridinary Portland Cement or should I use Portland Lime Cement?
I have a 2 month old nearly full bag of Ordinary Portland Cement that was stored in dry conditions.

Can I apply the concrete mix straight onto the old brick and cement plaster coat surface?

Does the below Mix ratio work fine?

Quote:

(i) First Coat or Rough Coat

Usually the average thickness of the first coat of plaster is 12 mm on brick masonry or ashlar masonry and 23 mm on rubble masonry. In case of concrete masonry this thickness varies from 9 to 15 mm depending upon the nature of work. For the first coat cement plaster with mix-proportions as 1 : 3 or 4 (1 cement : 3 or 4 sand) is generally used.

http://www.theconstructioncivil.com/2011/08/cement-plastering.html

I'll try and upload a picture of the wall section later, right now my isp is not being aggreable.

Thanks,

stuart45 07-06-2012 04:01 PM

Quote:

Originally Posted by Spud (Post 959018)
Non load bearing Brick interior wall that partitions off the bathroom. The cross section sides of the wall are to receive replacement door frames. The other 2 sides of the wall already retains the old cement plaster coat.

I need to apply about 0.5 inches of cement plaster coat onto the brick and remanants of the old cement plaster coat.

Questions:

What Concrete Mix ratio should I use?
1/1/4 lime/OPC/sand for the scratch coat and 1/1/5 for the top coat. We usually put 2 coats of plaster on top of this. Base 2-3mm top coat 1mm.

Do I need to attach a metal lathe, even though I am only applying 0.5 inches thick cement plaster coat?
Depends on the condition of the brickwork. You can cover the brickwork with a couple of coats of PVA.

Can I apply the 0.5 inches as 1 coat or do I need to do 2 coats?
2 coats is better

Can I use standard concrete mix ratio, the same used in contructing structural concrete columns?

Can I use Oridinary Portland Cement or should I use Portland Lime Cement?
I have a 2 month old nearly full bag of Ordinary Portland Cement that was stored in dry conditions.

Can I apply the concrete mix straight onto the old brick and cement plaster coat surface?

Does the below Mix ratio work fine?


http://www.theconstructioncivil.com/2011/08/cement-plastering.html

I'll try and upload a picture of the wall section later, right now my isp is not being aggreable.

Thanks,

Hope this helps.

Spud 07-07-2012 01:35 AM

Quote:

Originally Posted by stuart45 (Post 959361)
Hope this helps.

Thanks for the reply.

PVA = Poly Vinyl Acetate?

Instead of mixing separate Lime and separate Cement, can I just use Portland Lime Cement?

For the mix ratios, is it done by volume or weight? So 1 part cement : 4 parts sand would be sand that is 4 times the weight of the cement or 4 times the volume of the cement?

How long should I let each coat cure before adding the next coat?
For proper curing, should I keep each coat misted with water and for how many days?

stuart45 07-07-2012 05:36 AM

Quote:

Originally Posted by Spud (Post 959734)
Thanks for the reply.

PVA = Poly Vinyl Acetate?
Yes, it's a glue that evens out the suction and bonds the plaster to the wall. Mix 3/1 water/PVA

Instead of mixing separate Lime and separate Cement, can I just use Portland Lime Cement?
Probably, but I've never done it.


For the mix ratios, is it done by volume or weight? So 1 part cement : 4 parts sand would be sand that is 4 times the weight of the cement or 4 times the volume of the cement?
Do it by volume

How long should I let each coat cure before adding the next coat?
For proper curing, should I keep each coat misted with water and for how many days?

Most plasterers here put the 2nd coat on the next day. I'm a bricklayer, not a plasterer by the way.
I'm doing an extension at home today, I'll put a few photo's on later.

stuart45 07-07-2012 02:14 PM

3 Attachment(s)
Here's a few photos Spud.
If you have any windows nail some straight to the wall and do the reveals first.
Attachment 53655
This leaves this when you take them off.
Attachment 53656
Then strut more straight edges to the reveal and do the first coat and stratch it for a key.
Attachment 53657

Spud 07-08-2012 04:34 AM

Hi Stuart
This is the wall thats going to get plastered, then receive a door frame.

http://i42.photobucket.com/albums/e3...athroom006.jpg

I am going to be adding about 3/4 to an inch of plaster, due to the deep central channel. So I am going to apply 2 coats.

Should I affix a metal lath also? If so, I was goin to use 2 part epoxy glue to attack the lath to the brick and old plaster coat, should not be a problem?

stuart45 07-08-2012 02:55 PM

Looking at the job I wouldn't bother with metal lathing. A coat of PVA, wait till it goes tacky and then put the first coat on and scratch it for a key. Then put the top coat on flush with the other plaster and rub it smooth with a wooden float or a piece of wood.


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