Partial factors for materials for foundations: the value of kf
Eurocode 2 part 1-1: Design of concrete structures 2.4.2.5 (2)
The partial factor for concrete γC given in § 2.4.2.4 (1) should be multiplied by a factor, kf, for calculation of design resistance of cast in place piles without permanent casing.
Recommendation
The recommended value for kf is 1,1.