When a multilayer concrete beam is built, several concrete mixtures could be poured sequentially. Usually concrete used in external layers are higher resistance than those placed in internal layers. Time between the pouring of the different layers could have influence on the beam behaviour. The goal of this paper is to study how temporary offset on manufacturing the multilayer concrete beams has influence on their mechanical behaviour. Some has test have been run out to some beams which let us know the different behavior between each other. Finally it has been determinate if the construction process is the cause or other factors lead to produce the founded differences.