DIY exposed concrete wall retouching

Concrete is never really homogeneous. The walls shown are also far from fair-faced concrete. Just the unfinished surface alone… A lot can be achieved with grinding and sealing. If you want a uniform gray, the only option is to paint. If there are children in the house, definitely seal it. Otherwise, you will get fingerprints on the wall with every skin contact. Then my usual question: how should the joints be closed? There are special concrete paints. Usually, a primer is necessary to silicate the concrete. Personally, I would try grinding it (Hilti, for example, has a concrete grinding system). You can get it to a high gloss if desired. If you still don’t like it, you can paint and already have a smooth surface.

@dertill say more about that...

Nope .... I have no idea about concrete. :)

I would also quickly put up a sign on the walls that the concrete should remain visible. The first trades are already writing on the wall. Don't want you to have marking paint on the wall as well. Couldn't it have been executed as exposed concrete from the start?

The first trades are already writing on the wall.

The question is whether exposed concrete or raw building charm, there are fans for both.

Goes away with an eraser or when sanding.

Then my usual question: how should the joints be closed?

The joints do not bother us, on the contrary. I even find it quite appealing when the concrete wall is not "perfect"; that includes the joints of the formwork elements and visible anchor holes.

There are special concrete colors. Usually, a primer is necessary to silicify the concrete. Personally, I would try grinding it (Hilti, for example, has a concrete grinding system).

Yes, we will first clean and sand the walls. Then we'll see how it looks and decide whether a simple sealant is enough or if a tinted concrete glaze might be useful.

Couldn't it have been done as exposed concrete from the start?

Sure it could have ;-) We originally wanted to have the walls fully plastered and then painted. The idea to leave it as is only came up when it was finished.