How to fill small air bubbles left in concrete after removing formwork?
Question:Needing to have a smooth finish so i can apply render paint to a wall i am building. What is the best way to fill these air bubbles?
Any help would be great, cheers!
Answers:
First you should go out and buy concrete/cement bonding agent.
This will make sure you cement mixture will stick the concrete.
There are a few brands out there. If you live in Australia the best brand to buy is Bondcrete made by Bondall
http://www.bondall.com.au/customcontentr...
The Render
1 part Cement
1 part Lime
4 parts fine sand
4 parts water and one part concrete/cement bonding agent.
Add the fluid mixture to the dry ingredients till you have a smooth slurry.
Let the render stand for a couple of minutes while you hose down the area that you are about to repair.
Then using a trowel apply the render. When the render is nearly dry smooth the surface with a broom and a damp old towel.
Don't be in to much of a hurry to brush down a smooth the render because you may end up brushing the render out of the holes you are trying to fill.
http://www.homebaseexpo.com.au/building/...
Below are other brands of concrete/cement bonding agent you can buy in the USA.
http://www.wrmeadows.com/wrm00020.htm...
http://www.super-tek.com/superweld.htm...
http://www.primeresins.com/products/prim...
I have personally used Bondcrete and it really works. Another handy hint that works, is you can add a small amount of bondcrete to you house paint and it will never peel off. "Great for Ceilings"
spakle is the best way.
Portland cement mixed with water, use a trowel and work it in. Next time work the wet cement to force the air out.
Google "magic smooth". It's an easy to use epoxy resin that sculptors (like me) use to, well, make things smooth. I patch up LOTS of defects on old houses with it and "magic sculpt". Magic-smooth for 'air bubbles', Magic-sculpt for CRATERS.
If your concrete is reinforced cement, you'll have to fill the bubbles with a mixture of "Portland cement", sweet sand and water, so to protect iron from rust. Salted sand or water, and /or lime, will produce rust.
If there is no iron on your concrete, just ignore this first step, and proceed as follows:
1) Use an almost liquid mixture of cement and water, and "whip" the surface. Its used as anchorage.
2) After it drys, depending on how perfect and smooth you want the final surface, you'll have to put 2 or 3 layers of plaster.
2.1) first, a layer a layer of plaster made with rough (thick)sand.
2.2) then, a layer of plaster made with thin sand. And if you want it smoother;
2.3) a very thin layer, made from what we call in spanish "enduído" (plaster cast? - made with gypsum - sold in paint shops).
2.4) Sand paper all the surface. Once or twice.
2.5) Paint
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