Matt,
It is Altro, but really really neglected, extremely heavily used. To be honest, totally the wrong flooring but hey ho.
I have just read that, and a I dealt with this site a few years ago, I spent weekends with a rotary and a wet vac. Looks great when done but next day in this place its the same.
To be honest, even with a scrubber, you are limited to the amount you can do in one go, as I say its 24/7.
I once barriered a portion off in the night, cleaned that, moved on, and so on.
But the corridors are just footfall (albeit muddy and oily, no food and tea/coffee).
So I think a scrubber with a brush should be best?
Got to get this right, as I am doing cost estimate with this in mind.
Paul