The idea is to remove the concrete from the top of the grain of sand and keep that grain sticking underneath. The floor must be perfectly dry before prime coast is applied. May take several days even weeks depending on your weather and especially humidity.
The feel of grittiness depends on the...
I just used the two pot exoxy called Durabuild 401 from Dulux in Australia - painted it in plain grey as I though the flakes etc would not reflect the light and make finding nuts washers etc difficult to fine let alone seeing what oil leaks came from my British cars.
It's really good stuff does...