Have been reading the thread with interest until now. Thanks everyone.
While (to Sinker's possible disgust, thanks for posting the explanation!) I personally still would consider concrete bolts, after reading this although I'm very restrictive on when I'd think them suitable. Definite agreement that for anything longer than really really short term they are sketchy.
Just for your amusement value... for an temporary aid ladder I would favour them (6mm or 8mm) over brown rawlplugs (7mm hole) with occasional expansion bolt.
Worth repeating is that you can remove them easily (the same day?) and fill the entrance to holes with some grey resin and/or a broken bit of rock, which you could do when installing permanent anchors with whatever is left in the tube.
worth a mention and maybe winner for short term anchors are drop in anchors for *temporary* placements. Spit if you want. (pun intended). These should be removable with a ball joint separator bashed in behind a hanger (or HSS shoved down hole if really stubborn) *as long as* they are of the wedge-first variety which are hard to get. Fischer make a kind of screw-in version of this to allow removal, but only 12mm drill hole and upwards
Fair disclosure... I've not actually removed a sleeve or drop in as described above whilst underground, but it works in a concrete floor.