With the purpose of studying the mechanical properties of uncompacted rockfill and the creep deformation behaviour of rockfill under a load as well as finding a suitable method for estimation of creep deformation behaviour, a full scale embankment loading experiment was performed. The results of this experiment were then evaluated. During the course of this study it became evident to the author that the deformations which were seen in the collected data from the experiment could be classified as creep deformations due to the linear decrease of the deformation against the logarithm of time and the study therefore came to focus on creep. One constitutive equation and one model for estimation of creep deformations were studied, and parameters were obtained through back analysis of experiment data as well as calculation of soil stresses. The creep model was based on a logarithmic approximation of the creep deformations and the creep equation was based on a power function. The creep model could also be simplified and evaluated as an equation and when a comparison was made between the equations and the measured results this showed that the logarithmic equation resulted in estimates closer to the measured deformations than what the power function did, therefore a logarithmic function is a better approximation to the deformations of the rockfill at Norvik than the power function. When the creep model was evaluated as intended, based on the soil stresses, the resulting creep estimates were less accurate, they was however still within the limits of what can be considered as admissible. The conclusion is that a logarithmic function describes the creep deformation of the rockfill at Norvik better than a power function and that the creep model by Kristensen is suitable for estimating the creep deformations. This since the creep model also provides a way of estimating deformations occurring under stress conditions other than the ones for which the creep test was performed.