CNC gantry steel tube fill with concrete

[spikee]

Hi,

i want to make my steal beam on my gantry CNC to deflect less.
Currently at 164N on the middle of my beam i get 0.143 mm bending/deflection (this was 0.168mm @ 150N simulated).
The size is 1430mmx50x100 4mm thick. I'm looking for something which has a good bond with the metal. Anything you can recommend? i don't need to fill the full length. Making holes in the back for pressure releaf is not an issue.

I guess small shrinkage is also beneficial for this.

picture of my machine:
Kind regards,
Spikee

[dr.backstein]

Hello Spikee,

Normally, DURFILL® high strength expansive grouting mortar is used to fill cavities on machines. However, this is not primarily done to increase bending stiffness, but to improve vibration damping. You would simply have to try it out to see if it is right for your application.

Sven

[spikee]

Hi,

i want to make my steal beam on my gantry CNC to deflect less.
Currently at 164N on the middle of my beam i get 0.143 mm bending/deflection (this was 0.168mm @ 150N simulated).
The size is 1430mmx50x100 4mm thick. I'm looking for something which has a good bond with the metal. Anything you can recommend? i don't need to fill the full length. Making holes in the back for pressure releaf is not an issue.

I guess small shrinkage is also beneficial for this.

picture of my machine:
Kind regards,
Spikee

Thanks for that. can it be diluted with aggegrate (KÖRNUNG) to reduce weight and volume of cement to be used?

[spikee]

I'm also a bit confused regarding datasheet:

Use as effective supporting composite (thin-plate construction): The steel structure is designed as a composite material with a thickness of 5 to 8 mm, e.g., in accordance with Eurocode 4 (DIN EN 1994-1-1). For additional strengthening and improving the stiffness, reinforcing steel BSt 500 or a steel structure can be welded on. This design method results in fine cracking of the concrete; its stiffness can be calculated in accordance with Eurocode 4.

If i understand correctly here it says support in thin plate construction -> do not add reinforcements as the concrete cracks.

in the end at shear forces:

This is not possible using rectangular or circular hollow profiles. Therefore every 100 mm horizontal and vertical holes are drilled, through which threaded bolts Ø 16mm or reinforcement bars Ø 16mm are placed and fixed by welding. It is sufficient to do this at the beginning and at the end of the profiles, since in the middle third the shear forces are usually low. In stainless steel tubes, the same method can be applied using screws instead of welding.

In my application do i need to add reinforcements in middle of tube?
Do i need to add reinforcement bars at the "side" of my tube where it connects with the rest of the machine?

[dr.backstein]

Hello Spikee,

I do not recommend mixing in additional aggeragate. As far as your bonding questions are concerned you should ask DURCRETE who wrote the instructions that you refer to. I don't think that in your case welding on extra steel rebars is necessary.

Sven