Can I use cement instead of paint for interior walls?

Question

I live in Mumbai (India) where clay brick walls are reinforced with concrete. On the interior part of these walls (inside the house), some layers of plaster followed by a layer of oil paint or any other paint is applied. Having read somewhere that these paints are toxic, I wonder whether I can use cement/concrete as a coating for the interior part of the wall. Maybe I will apply a thick layer of white cement with some color pigment.

Generally, people paint walls with oil paint after applying 2-3 layers of plaster (Plaster of Paris) and Distemper.

If yes then, some of my concerns are:

1. Durability: will it scrape off in few years like plaster due to water erosion etc?
2. Health and safety: is it toxic?
3. Time needed for the cement to settle.

Feel free to add more to this list, if you have any.

Answer 1

Cement is acceptable as an interior finish. The reason why it isn't used more is that it is heavy and terribly hard to make look nice. Basically once it is dry it is done for good. Also cement adheres to dry cement but not that well so patching is not easy.

As for durability it depends how you prepare the surface and the thickness of the install. In my area it was a thing to finish basements with a cement coating (over the poured cement walls). These went on about 1/4-1/2" thick and looks a bit like plaster after a few coats of primer and paint. You can certainly give the concrete a pigment but it has a pretty prickly surface that a thick coating of paint would help smooth.

The other thing to think about is hanging things on the wall or doing things like electrical. You have to know that if you hang something on the wall you will need to use adhesive. If it is something heavy you might have a hard time taking the adhesive off without ripping out the underlying cement. In the older basements we would go in we would see dozens of little cement patches missing from things like pictures or whatever.

Answer 2

I think you'd have to do it like you do stucco here in the states - attach a type of metal lathe or wire mesh to the wall to help hold and reinforce the concrete. Would probably need to prepare the surface underneath - oil based paint likely isn't good substrate. And use the right kind of concrete.

Regarding your 3 questions...

1. Durability - done right, I think it could be very durable, but there are issues with the substrate as I mentioned above.

2. Health & safety - Once cured, concrete is very safe. It's a strong alkali which can produce chemical burns before it's cured.

3. Time for the concrete to set - it will be to hard to work with within an hour or so max. Depends on mix, weather, etc. Essentially cured in about a day, full strength in about a month.

Regarding the safety of the paint - here in the US the primary concern is lead based pigments. If chips or dust from lead based paints are inhaled or ingested it leads to significant neurological deficits, especially in children. Again in the US, it's pretty easy to get paint chips tested for lead.

If you have it, then there are a variety of ways to mitigate it. But anything that creates alot of dust or paint chips is a bad idea. If it's adhering well, your best bet may be to leave it alone.