It is described a basic core component (240, 740, 840, 940, 1040, 1140, 1240a-c) for forming, together with at least one another basic core component, a core structure of a rotor blade of a wind turbine. The basic core component comprises a precasted base element (110, 210, 310, 710, 810, 910, 1010, 1110) being made from a foam material (468, 568, 668), and a resin receiving layer (120, 220, 320, 420, 520, 620, 720, 820, 920, 1020, 1120), which is adhered to at least one surface of the precasted base element. When, during a casting procedure, the resin receiving layer adjoins the surface of another basic core component, the resin receiving layer is adapted to receive resin such that, after hardening the received resin, the basic core element and the another basic core element are mechanically connected with each other. It is further described a structural support assembly comprising at least one of such a basic core component and at least one further basic core component. Further, it is described a wind turbine rotor blade, which comprises a core structure comprising at least one of such a structural support assembly. Furthermore, a method for manufacturing such a basic core component is described.