Concrete on concrete, freeze damage? Casting tracks in garage floor in cold garage for new floor drain

[Knallskalle]

Wondering if I'm missing something important, as it's much harder to redo than to do it right from the start.

The picture probably says it all. There's good slope in the garage today, so no need to adjust it.
The previous pipes (concrete pipes from the 60s) have likely frozen and broken as it's an uninsulated cold garage. Had to remove so much because the pipe was completely broken and needed to be chiseled away before I could fit pipes into the remaining section.

Plan to pour concrete in the spring when the weather allows since I don't want to deal with winter concrete.




My plan is to:
Cover the drain's top to avoid mess.
Mix coarse concrete and pour it in. Vibrate with a homemade tool attached to a drill.
Even out so it aligns with the surrounding floor.


My considerations:
Since the old one likely froze and broke due to being an uninsulated cold garage, do I need to do something special to minimize the risk of this happening again? The new plastic pipe is more flexible than the old one, so there's probably less risk of this.
The seam between new and old concrete, could water seep in and then freeze and crack? If so, how do you prevent this?
Can I skip reinforcement in this narrow case, or should I throw in some iron?

I've also thought about maybe painting the floor with some epoxy paint to give it a more durable surface on the old concrete. Noticing it becomes porous from solvents (clearly visible where there were a few drops of chain cleaner when I cleaned the bike chain even though I wiped it up).

 

[Knallskalle]

Since I haven't received a response, I'll simplify things here.

I'm planning to proceed as follows, let me know if you think anything is unnecessary or overkill.

Brush clean, as dust-free as possible
Keep it moist for a few days according to the instructions for korrohäft
Cover the drain with plastic
Mix and apply korrohäft to the walls (assuming it's not needed on the drain)
Directly after korrohäft, mix concrete, using Finja coarse construction concrete since it's runoff water from a car with salt, so I want the most durable option since the price difference is minimal for this amount
Use a concrete vibrator to settle the concrete and place some reinforcement bars
Wait an hour
Smooth out and remove the plastic around the drain once it's stopped running and fine-tune the slope around the drain.
Cover with plastic and keep it moist for a few days so it cures without drying too quickly.