Wrong concrete in the foundation? XC3 instead of XC2

Hello everyone,

with us, the foundation (reinforced) was poured with a concrete C 20/25 XC3.

Now I have learned, however, that normally an XC2 is used for foundations.
According to the standard, XC3 is used in air environment and only moderate moisture?

Is XC3 now wrong? Does it have any consequences that could occur over the years?

Regards
Arthur

What do the expert, executing company, concrete plant, and GÜ or architect think about this?

Hello "partyarti". The concrete exposure class designation XC2 is required when corrosion of the reinforcing steel due to carbonation of the cement paste is to be feared. Depending on the environmental conditions to which concrete is exposed, a distinction is made between classes XC1 to XC4. The latter class is used under the "most severe moisture conditions". However, in your building, we are not talking about an industrial hall, but possibly a residential building. This means that the floor slab is covered, moisture can only come from below - and then must be sealed from the rear if the earth-contacting rooms in the basement are not intended for secondary purposes only. Evaluating this is the planner's responsibility. But ultimately, there will be no CO2 accumulations under the floor slab that would make the initially mentioned exposure class necessary at all. In an exposed production or storage hall, this could be decisive. In a residential building, however, not! --------------------------------------------------------- Regards: KlaRa

what does the construction service description say? if it says xc2 there, the discussion is over. otherwise, either listen to klara or have an expert take a look at the matter.

Hello everyone,

first of all, thanks for your answers.
I had many phone calls the following day:
Statement from concrete plants (where the concrete was ordered): XC3 is higher quality than XC2, so there should be no worries. The plant no longer produces C20/25 XC2 as a standard, only from XC3.

Statement from another concrete plant: same as the statement above.

Statement from the architect: no problem, XC3 is better

Statement from the structural engineer: see the architect's statement

Best regards

Arti