Can I add Aluminum Oxide for texture to your Polyurea cartridge kits?
Unfortunately, the cartridge system products are designed to cure within seconds, not minutes, and is combined in the mixing tube. I am not sure what your specific plan is, but in general, you would normally expect to take a couple of minutes to fully deplete a cartridge at any rate (in which case, the starting point would be cured). In this case, you would not be able to go back to the starting point and have any broadcast medium actually settle into the applied coating.
Depending on your surface and purpose, you could consider spraying a base coat, broadcasting your medium, and then sealing with a light spray overcoat. You might also be able to spray your base coat, and then have another individual broadcast your Aluminum Oxide as you spray a light top coat. This same thing could be done by broadcasting as the initial coat is applied. Just be sure to utilize the same respiratory protection for any assistants as you would employ for yourself.