Are butt joints in ready-mix concrete basements acceptable?

Hello everyone,

I was in our prefabricated basement for the first time yesterday, before the ceiling slab was concreted. Now two things caught my eye negatively. On the one hand, the joint seams were partly quite large in my opinion. On the other hand, it looks like two concrete elements were slightly chipped at the joints during assembly, and now the concrete is crumbling there.

When I asked, the foreman said that fresh concrete will still flow into all the joints, and the crumbling spot will be filled in.

Does anyone have experience whether this is okay? For me, it’s actually less about the appearance (utility basement) and more about whether this is simply sloppy work or even structurally questionable.

Let’s see how it looks after the concreting. I’m meeting with the site manager at noon for acceptance, but I wanted to hear what you think beforehand.

Regards King Julien

Looks like a big pile of crap to me personally.

So the first images look more like this is an element or is that deceptive? Because you can also see the reinforcement there, can't you? For me, that definitely looks very, let’s say "nice", exciting. So I would certainly agree with Bookstar, as I said, the first images almost look as if the slab were "broken".

We took a look at a prefabricated basement from the company Dennert shortly after it was set up, and it looked perfect. There wasn’t a single spot as badly finished as yours, but that was also a prefabricated basement, so nothing was concreted anymore. However, I would still get an independent expert opinion.

So the first pictures look more like this is an element or is that deceptive? Because you can also see the reinforcement there, right?

You are right! I didn't notice that yesterday in the heat of the moment. This is not a good start
Then I will definitely have that recorded as a defect. Let's see what the general contractor's site manager says about it.

At first I thought someone had taken "Stoßfuge" too literally as a bump or bang joint, but on closer inspection it looks more like a crack to me, on both sides of which there is now almost a exposed aggregate surface. From my point of view, that needs to be replaced before the ceiling goes on. Where is the cast-in-place concrete supposed to flow in - are these exterior walls whose prefabricated part only consists of the two "formwork layers"? It seems to me someone wanted to quickly deliver these parts in a hurry and therefore loaded them before they had properly set.