bathroom renovation - time for concrete to cure

[norman]

I have a query about floor preparation.
The concrete in our bathroom was poured and left to dry for four days.
Then the waterproofing membrane was painted on.
The next day, air bubbles had appeared in the membrane and a second coat was put on.
The second coat was left to dry for two days and then the screed went on.
Is 4 days long enough for the concrete to cure? Temperatures at the time were average, probably between 20 and 30 degrees celcius during the day.

 

[david campbell]

was the painted waterproofing bitumen paint?

 

[norman]

I don't know. The paint was white and had bits in it which the tiler said was fiberglass from memory.
I rang up two tilers today and they both said that the air bubbles mean that the waterproofing has not bonded to the concrete and that the concrete was still too green and should have been left longer.
What does this problem mean in real terms for me and my property...does it potentially mean leaking floors in the next room?
Also, our tiler put the waterproofing on the concrete before putting on the screed - should it have been done the other way around?

 

[DHTiling]

Not a method i have knowledge of in Oz....maybe one of our australian members will reply to your quiery......

 

[bighen]

As to why he's painted a waterproofer on I don't know.:yikes:
You would normally concrete on top of a plastic DPM - or lay 100mm of concrete followed by DPM, insulation then 75mm screed.To paint a waterproofer only 4 days after concreting will present problems, especially if this is to be your main DPM.
With regards to curing, concrete or screed will cure in proportion to time and temperature. So times are rarely quoted as temperatures change so much. Curing refers to the setting of the concrete though, not the drying. Concretes are batched on the basis that they reach their design strength after 28 days.

As a general rule of thumb you should-

• Allow at least 6 weeks for new concrete to cure with air drying before applying a screed or directly bedded materials.This time may have to be extended in wet weather (refer to BS 5385: Part 3: 14.2.3 for curing standards). If this is not followed then when the concrete shrinks, the bond between the adhesive and the concrete will be broken.
• If you wish to tile asap, use an external reinforced decoupling matting system such as a Shlüter system, along with a polymer modified adhesive such as PCI’s Tilefast 6 RapidFlex.
• If your using vinyl sheeting, where a 150mm-thick concrete slab is laid on to a suitable DPM (Damp Proof Membrane) is used, it can take up to a year to dry.
• If your unsure as to whether there is a damp proof membrane below the concrete (I wouldn't trust the painted on one) which will prevent the moisture rising, consider using a surface membrane such as SDPM (Surface Damp Proof Membrane).
• Use a primer, such as PCI’s Primer G, if the concrete is dusting or the porosity is high.

Hope this helps

 

[norman]

thankyou, you've given me some questions to ask.

 

[grumpygrouter]

Nice answer Bighen.

 

[bighen]

Thanx Grumpy:8:

 

[willicooper1]

Painting coats over coats is not the solution of your problem because there can be any leakage in floor which you can't stop by paint.I know a contractor you can take help from him.


______________________

 

[heavytrevy]

Got some bad news for ya, The concrete that was first poured needs to dy for at least a mth.
The bubbles appearing are related to moisture trying to escape.
Green concrete needs to have an epoxy type waterproofing.
If its a regular acrylic/polyurethane WP it will fail.

This one will do the job Broken Link Removed

If ur tiler hasent use an epoxy type wp and is unwilling to remove the screed and existing WP u can leave it to dry for 3 weeks and go over the top with normal acrylic/polyurethane WP.
You need comfirm which type was used.

Regards
Trev

 

[Scott]

This was posted in April 2009 so its probably dry by now

 

[Time's Ran Out]

What happened to bighen - good info was received there.

 

[jay]

Got some bad news for ya, The concrete that was first poured needs to dy for at least a mth.
The bubbles appearing are related to moisture trying to escape.
Green concrete needs to have an epoxy type waterproofing.
If its a regular acrylic/polyurethane WP it will fail.

This one will do the job Broken Link Removed

If ur tiler hasent use an epoxy type wp and is unwilling to remove the screed and existing WP u can leave it to dry for 3 weeks and go over the top with normal acrylic/polyurethane WP.
You need comfirm which type was used.

Regards
Trev

youve got it all covered trev

 

[heavytrevy]

haha too bad it was a thread dig rrr: