Optional increase of cover for concrete abrasion: the values of k1, k2, k3
Eurocode 2 part 1-1: Design of concrete structures 220.127.116.11 (13)
Optionally concrete abrasion may be allowed for by increasing the concrete cover (sacrificial layer). In that case the minimum cover cmin should be increased by k1 for Abrasion Class XM1, by k2 for XM2 and by k3 for XM3.
The recommended values for k1, k2 and k3 are 5 mm, 10 mm and 15 mm respectively.