Casting mold wall: Lid on L-shape?

[Nytt användarnamn_2024_1]

I have manufactured a stable casting mold according to the sketch. The base of the mold is currently "open," i.e., no cover/sealing upwards. According to remarks, the mold must be covered at the base, otherwise, there's a risk of all the concrete being pushed out when filling the vertical part.

The mold is about 13 meters long.

I am having trouble keeping the mold down against the ground - If the cover is attached to the mold (e.g., through struts against the inside of the mold), I believe the whole mold risks being lifted when the covers are pushed upwards by the concrete pressure. A calculation gives approximately 300kg per meter in lift force on the cover. Has anyone else calculated the forces needed to hold down the cover when the mold is filled with concrete? The outside of the mold is somewhat secured in the ground but not designed to handle several tons of lift force.

Any ideas on how you usually solve this? I will be using normal concrete (i.e., not SCC/self-compacting concrete)

 

[Plupp 405730]

We have cast ready-made long L-shapes with lids, but we have hand-cast points in the form before the big casting as a counterweight, perhaps every 1-1.5 m with 2-4 bags of hand-mixed concrete.
You must have a counterweight, otherwise, the whole thing will lift...

 

[Nytt användarnamn_2024_1]

Anyone calculated the cr

calculated the forces needed to hold down the lid when the form is filled with concrete? According to remarks, the form must be covered at the base otherwise all the concrete risks being pushed out when filling the vertical part.

We have cast ready-made long L-shapes with a lid, but we have handcrafted points in the form before the big casting as a counterweight maybe every 1-1.5 m with 2-4 bags of hand-mixed concrete.
You must have a counterweight otherwise the whole thing will lift..

Do you mean 2-4 bags every other meter or a total of 2-4 bags? How high was your wall? Any anchoring in the ground in any way?

 

[Plupp 405730]

Do you mean 2-4 bags every other meter or a total of 2-4 bags? How high was your wall? Any anchoring in the ground in any way?

No anchoring in the ground, no iron should lie against the ground because they rust and damage the concrete..
2-4 bags every other meter..
Then it is important that you make holes in the lid at the back end, say about 600-800 c/c so that you can see that the concrete comes all the way when you cast..

 

[snickar]

Is it an option to cast the bottom first and wait a day before casting the standing part?

 

[Nytt användarnamn_2024_1]

Is it an option to cast the bottom first and wait a day then cast the standing part?

Yes, but I would prefer to cast everything in one go. But it will be about 100kg per 10cm and meter in pressure..