In uk.d-i-y, Bob Minchin wrote:

The trade call these 'chemical anchors' - try a google search. I guess
your problem will be finding a retail source for a small amount.

As it happens, Screwfix do sell small quantities: they call the size
which goes into an ordinary sealant gun product number 16180, 150ml
for a cute 5.35quid. Few d-i-y'ers will find it hard to make up other
Might Come In Usefuls to get past the 45quid small-order surcharge...
in the case of the Original Poster, f'r instance, they'll sell you
studding in metre lengths or precut bits...

Stefek "no commission from Screwfix or RS"