Try this recipe: https://www.craftylittlegnome.com/permanently-kill-grass-weeds/
Here are a few options that should work well
1) Sprinkle handfuls of baking soda onto the concrete and simply sweep it into the cracks. The added sodium will make it much less hospitable to dandelions and their friends.
2) sprinkle borax into all the crevices where you’ve seen weeds grow in the past. It will kill them off before they have a chance to take root. When applied around the foundation of your home, it will also keep ants and other six-legged intruders from entering your house
3) Place a series of carpet scraps upside down and cover them with bark mulch or straw for a weed-free garden path
4) Bring a solution of about 1 cup salt in 2 cups water to a boil. Pour directly on the weeds to kill them
5) For a quick and easy weed killer, mix 1 ounce (30 milliliters) vodka, a few drops liquid dish soap, and 2 cups water in a spray bottle
Here is video tutorial for you: https://www.youtube.com/watch?v=2zCS-rfT3Xk