You can fill cracks with cement crack filler in bottle or caulk tube.
I’ve used two brands of this caulk-tube concrete crack filler and I can’t remember which one was great and the other was terrible.
It has a predominately safety yellow and black colored tube.
One was from Home Depot and the other, Lowes. I’m guessing the Lowes product was better.
If in doubt, buy both. You’ll need more than one tube. 😉
Check out Sika. I've not used it but saw an amazing demo.
You need to re-create a mixture using cement and water but make sure it's more liquid than solid. When this is done then add the mixture in the cracks and use a sponge to clean the excess