When do theoretical damages to the foundation slab become visible?

Hello everyone,

if the fresh slab gets exposed to too low temperatures, there are supposed to be frost damages. Can one roughly say when such damages would be visible – if they exist at all –?

Currently, our slab is being poured and outside it is only a few degrees above 0. At night it sometimes drops to -2°C or -3°C.

According to the construction workers, that probably wouldn't cause any problems, yet I can't get rid of my concerns.

Regards

Unfortunately, your question cannot be answered concretely. Of course, long-term damage can occur due to frost and moisture, but it depends much more on how carefully your construction company works. However, the same/similar question was asked and discussed in this forum.

Hopefully, I have been able to help!

Thank you for the quick reply. Unfortunately, the link does not work – I always get a page loading error here.

Can you check the link again or send it via PM?

Hello "Stockheim". It would become dangerous if the freshly poured concrete slab freezes through. Then there would indeed be significant strength losses in the concrete. But! We are talking here about a massive component. And at 2-3 °C below zero, a concrete slab cannot possibly reach a temperature below 0°C overnight. That means: it certainly cannot and will not freeze. However, the strength of the concrete is a result of a chemical reaction between (Anmach) water and cement. And the speed of the reaction process is (as we still know from chemistry class) temperature-dependent. Not only with concrete, but also with all reactive resins, which are exposed to low temperatures immediately after installation, there is a delay in hardening. With cement + water, however, the reaction starts again when the temperature rises. In my opinion, there is no need to "spook horses" in your case. --------------------------- Regards: Klaus

And concrete produces heat while setting. Nothing freezes at a few hours of minus three. Therefore .... everything bongo. No fear. Karsten

ok, then I am relieved! I looked under the foil this morning and took a photo. These white spots are definitely due to the hardening, right?

Is there actually any standard that specifies how much tolerance a floor slab is allowed to have? I was at the construction site yesterday and had to find out that the formwork was not held properly in one spot. So the floor slab is not straight at that point but has a slight bulge. Attached are 2 photos of it