Underpinning: Use Thermal Foundation Blocks (Leca) to insulate?

[Christian Andersen]

Underpinning: Use Thermal Foundation Blocks (Leca) to insulate basement foundation to avoid a Thermal Bridge?

I want to insulate a basement floor. The basement walls are at the same time insulated on the outside between basement wall and soil.

The basement foundation needs to be underpinned to make room for the insulation under the new concrete floor. If I underpin the existing foundation using concrete I will still have a cold thermal bridge through the foundation to my floor/wall corners of my otherwise well insulated basement.

So I wonder: Can I use (Leca) Thermal Foundation Blocks between my new underpin foundation and the existing foundation to insulate the foundation, to avoid the foundation being a cold thermal bridge?

I imagine I will excavate 0.65 meter under the existing foundation, cast a 0.40 meter high reinforced new foundation, leaving 0.25 meter, between top of new foundation and bottom of existing foundation. Here I lay a thermal foundation block (eg. Leca) height 0.20 meter and the remaining 0.04 meter is used for expansive concrete.

Please give me some comments on this construction.
Any problems / faults?

I plan to use stronger thermal blocks like 4-5 MPa blocks as opposed to 2 MPa blocks used for 1-2 story houses.

Drawing attached. Thank you!

 

[Christian Andersen]

Sorry, Here is the drawing.