For people asking about how to repair chunky curbs it's not that hard, but definitely time consuming. Here's how I did it:
1. Scrape all the wax off. First with a paint scraper then with a scouring pad with acetone. All of it has to come off.
2. Optional and expensive step but pour concrete densifier on it. This fills air voids and hardens the concrete.
3. Get an angle grinder and a Diamond polishing wheel. They're usually gold and they sell them on Amazon. Make sure it's rated for high RPM.
4. Go along the curb and start hand grinding it and make sure to create a rounded profile. You can grind and polish the rocks.
5. Optional. Fill any large voids with JB Weld Steel Stick.
6. Optional but recommends. Get a hand drill and some 50-100 grit cement polishing pads and start getting it smooth and polished. Way better than a brick IMO but a brick will suffice. Bonus points if you can wet sand.
7. Put some Glaze N Seal over it.
8. 1-3 coats of a thick exterior clear.
9. Optional, but use a fine sanding sponge and wet sand it.
10. Done
I made myself a concrete parking block and I didn't vibrate it enough and it came out like Swiss Cheese. By using some Sika to patch the holes and the steps above I actually don't even need to wax the thing and it slides extremely well.