DIY'er wants to use some 50 or so left-over quarry-tiles to tile inside an external cupboard/shed, which has a concrete floor.

I've read you're supposed to use mortar with quarry-tiles? But that sounds a bit difficult, and I was just wondering if it's possible to use normal tile adhesive and if that would be easier.

As I said, it's inside a cupboard/small shed so it's not going to get any real foot-traffic. The aim to just to raise the floor/level slightly to maybe keep items inside above any damp/rainwater creeping in under the door (not that I'm expecting much), and also just to beautify it a bit, though it's not exactly in a much-viewed spot. I'd just rather keep to the minimum bother with it!

Many thanks for any tips.

use a cement based floor adhesive , dont use the ready mixed tub addy as its not suitable for quarries

buildfix from B&Q or better still mapei from tilegiant