Connecting element for constructing a t-shaped composite

A connecting element for constructing a T-shaped composite of three plates, comprising:

• a first contact surface configured to be mechanically coupled to a rear outer surface of a first plate;
• a second contact surface configured to be mechanically coupled to a rear outer surface of a second plate;
• and
• a coupling element coupled to the first contact surface and the second contact surface;
• wherein the coupling element is formed in two parts;
• and the coupling element is configured by a first partial element, which has a curved tongue, and a second partial element, which has a arcuate recess corresponding to a shape of the curved tongue, to cooperate upon pivoting of the partial elements moved together in such a way that a positive connection of an edge of a front outer surface of the first plate with an edge of a rear outer surface of a third plate results when the third plate is mechanically coupled by a web which connects a front outer surface of the third plate with a front outer surface of the second plate, in an angled manner, in order to arrange the front outer surface of the first plate in alignment with the rear outer surface of the third plate, adjacent to one another, in the T-shaped composite.