ᐅ Repairing holes in a concrete floor – debris and sand underneath

Hello, we have just purchased an old building and now have many questions. For example: we have a concrete floor with a large hole in it. Below the hole, there is a cavity about 5-10cm (2-4 inches) deep, followed by debris and sand. I would like to fill this hole with mortar, but does that work on a sandy base? Can I simply apply mortar generously once it has dried through, or will I face the same issues again in spring as we do with our roads?

I look forward to your answers...

Best regards, Thomas

Pictures say more than a thousand words...

Year of construction?
How big is the hole? And where has the reinforcement gone?

...I would like to upload images. My phone photos are still too large even after resizing. Thanks in advance for the response!

@koolkoe

Please send me your mobile phone pictures at [E-Mail]Info@schenk-Bauberatung.de[/E-Mail]. I will be happy to upload them for you.

Best regards, Bauexperte

Done

Greetings, Bauexperte

Am I correct in understanding that this is not an indoor floor but an outdoor surface?