International Catalogue

▸ Expert tip
▪ Standard concrete qualities:
C12/15 to C 50/60, even higher qualities are available for special applications.
The anchors that are mainly approved for concrete may be used from a concrete
quality of C 20/25 up to a max. of C 50/60.
▪ C 20/25 means:
C = Concrete
20 = Compressive strength f ck or f ck,cyl of a concrete test cylinder
(Ø 150 mm, height 300 mm) in N/mm 2
25 = Compressive strength f ck , cube of a concrete test cube (edge length
150 mm) in N/mm 2
▪ Normal concrete without accelerating additives reaches its nominal strength after
28 days. Only then can the fixing be applied, in compliance with the approval.
▪ Fresh concrete: still processible up to an hour after laying.
▪ Green concrete: up to 4 hours old, hardening, no longer processible.
▪ New concrete: 4 hours to 28 days old, hardening, minimum
compressive strength not yet reached.
▪ Hard concrete: older than 28 days, hardened, nominal strength reached.
▪ Anchors used in new concrete must be suitable for it or may be loaded only
after reaching the minimum compressive strength.
▪ Concrete always shows cracks (shrinkage during hardening, burdening)
▪ In cracked concrete, crack-suitable anchors must be used, which must be able
to expand for opening of cracks (expansion anchor, e.g. FAZ II), anchor via form
lock (undercut anchor e.g. FZA) or the adhesive bond must be suitable for the
tensile area (injection, e.g. FIS EM).
▪ Cutting through reinforcement steel while making drill holes is not permitted.
In special cases, non load-bearing steels can be cut after consultation with the
responsible structural engineer (diamond coring).
▪ The concrete must be load-bearing along the entire length of the drill hole
(no honeycombs or cavities).
Basic Knowledge of Fastening Technology
451