A method for providing a connection between concrete parts. One of the concrete parts is provided with a number of encased, projecting reinforcing bars. The other concrete part is provided with a series of cavities in which said reinforcing bars are placed and are then fixed to the concrete part in question by being encased. The cavities are produced by encasing a body, which at least on the outside comprises a polysiloxane material, in the concrete. When a tensile force is applied to the body a considerable reduction in its cross section takes place, so that it is possible for the non-sticking body to be removed from the concrete in a simple way, after which the desired cavity remains.