New basement wall, casting footing (Concrete C20/25)

[spaxx]

Hello,

Excavating the basement. Planning to divide the basement and put up a new wall. I need to cast a footing where the new wall will stand and build it up with lightweight aggregate blocks.

Can I cast the footing with coarse concrete C20/25 + rebar or will it be too weak? Should I use C32/40 instead?

There's a significant price difference between these, hence the question.

 

[spaxx]

Anyone know?

 

[rävlyan]

Probably doesn't matter much which type of concrete of the two, as long as the sole is wide and thick with iron in it so it can float on the substrate that should be quite rigid.

 

[spaxx]

Thank you, yes, even if it's C20/25, it should still withstand more than 5 mpa in compressive load. The wall above will be Leca, and it has about 3-5 mpa.

 

[rävlyan]

Just make sure the sole is reasonably wide, maybe 20 cm outside the wall, so it can bear the pressure without moving downward, with solid ground underneath. Two 12 iron bars beneath distribute the load and pressure with the future wall. The thickness of the sole should be at least 10-15 cm with the irons about 5-7 cm from the bottom of the sole, it's there any breakage occurs, think about it when you break a board, the splinters appear on the underside.

 

[spaxx]

Just make sure the foundation is reasonably wide, maybe 20 cm outside the wall, so it can bear the pressure without moving downward, solid ground underneath 2 pcs 12 iron underneath with the future wall distribute the load and pressure.
The thickness of the foundation at least 10-15 cm with the iron at about 5-7 cm from the bottom of the foundation, because that's where any breaks occur - think about it when you break a board, the splinters are on the underside

Thanks, pretty much what I was planning to do. Nice to know someone else thinks the same way.

 

[spaxx]

This one is cheap now, and only 99kr shipping
https://www.bauhaus.se/probau-grovbetong.html

I think I'll go with it