In chemical anchor fasteners, a special adhesive is used to stick the anchor into the hole. It is then filled with the chemical adhesive. The bolt is then inserted. The adhesive should completely fill the gap between anchor and hole, and should spill out of the hole when the bolt is inserted.
The chemical will then set - quick setting chemicals may set in an hour, while the more common ones may take 24 hours - and only after it is set may one apply load on the anchor.