By taking into account the increase of internal friction of hardened cement paste under permanent stress a relation for the macroscopic activation energy is derived, from which activation energy can be evaluated for the complete creep process. In the same way another equation for the change of activation energy is found as function of the duration of load. By means of extrapolation the activation energy at the beginning of the creep process can be determined approximately. Then the activation energy can be calculated throughout the duration of the creep process.