Micro-topping
A very thin polymer-modified cement coating troweled over existing concrete to create a smooth new decorative surface, typically a fraction of an inch thick.
What does micro-topping mean?
Micro-toppings resurface worn or unattractive concrete without the weight and height of a conventional overlay, which matters where door clearances and transitions are fixed. Being thin, they depend entirely on bond and on a stable substrate, and any substrate crack or movement will telegraph through. They are usually stained or dyed and always sealed.
In practice
It is a common way to rescue an ugly interior slab, and a common failure when applied over a slab that is still moving or was never profiled.