Anti-slip aggregate
The last thing that goes on the floor, and the first thing you notice wet
Aluminium oxide is the grit on the sandpaper in your workshop. Broadcast into the final polyaspartic coat at around 150 grams a square metre, it is what takes a resin floor from R10 to R11 wet: the difference between a ramp you can walk up in the rain and one you cannot.
It is the cheapest material on this page by a distance and the one most often left off a quote, because a floor without it is indistinguishable from a floor with it until the day it gets wet.
Slip resistance is not gloss level
A matt floor and a gloss floor of the same resin are about as slippery as each other when wet. Sheen is how much light scatters off the surface; grip is whether there is anything standing proud of it for a shoe to catch on. They are unrelated, and conflating them is the most common misunderstanding we deal with.
If a floor needs to be safe wet, it needs aggregate. There is no finish that substitutes for it.
Grade, and the trade you are making
Coarse grit grips harder and is unpleasant to kneel on, holds dirt and chews mop heads. Fine grit cleans easily and gives less grip. We use 46 to 60 for ramps, wash bays and external thresholds, and drop finer or leave it out entirely in dry internal areas where the risk is not there.
It is applied by zone, not across the whole floor. A garage usually gets it on the apron and the ramp and nowhere else.
It does eventually wear
The grit is far harder than the resin holding it, so what wears is the resin around the grains, and after enough years the grains come out of the traffic line. A fresh topcoat with a new broadcast puts it back without touching anything below.
That is a maintenance item and it should be on your schedule, not a surprise.
How to tellWet a patch and put a flat palm on it, then push sideways. Grit in the topcoat still grips wet. A floor where the slip resistance came from a matt finish rather than an aggregate feels exactly as slick wet as a gloss one.
What to ask
Ask which specific areas get anti-slip aggregate and to what grade, marked on a plan. "The floor will be non-slip" is not an answer; a gloss topcoat with nothing in it is sold that way every day.