A connector for tying together opposed foam panels (14A, 14B) in spaced and parallel relationship along a longitudinal direction to make a form for receiving a flowable material, the connector comprising: a pair of elongated anchor members (20A, 20B), having each a flange plate being devised to be embedded longitudinally inside a corresponding one of said foam panels (14A, 14B), each of said lange plates having two opposed extremities (90, 92) having each an extremity flange which is perpendicular to said flange plate and inwardly extending from it and a connecting member for connecting longitudinally the anchor members (20A, 20B) of the pair together, said connector being characterized in that: a head piece is projecting along the longitudinal direction from each extremity flange, each head piece has an L-shaped cross-section having a transversal arm defining said terminal surface which extends parallel to said extremity flange and having a longitudinal arm connecting the transversal arm to the extremity flange and each head piece covers half of the extremity flange, the head pieces at the upper and lower extremities (90, 92) of each flange plate cover each half of its extremity flange and are in axial symmetry to each other, so that, when two connectors are connected on top of each other, the terminal surface of the head piece at the lower extremity of the flange plate of the upper connector is in contact with the extremity flange at the upper extremity of the flange plate of the lower connector and the extremity flange of the lower extremity of the flange plate of the upper connector is in contact with the terminal surface of the head piece at the upper extremity of the lower connector. a pair of elongated anchor members (20A, 20B), having each a flange plate being devised to be embedded longitudinally inside a corresponding one of said foam panels (14A, 14B), each of said lange plates having two opposed extremities (90, 92) having each an extremity flange which is perpendicular to said flange plate and inwardly extending from it and a connecting member for connecting longitudinally the anchor members (20A, 20B) of the pair together, said connector being characterized in that: a head piece is projecting along the longitudinal direction from each extremity flange, each head piece has an L-shaped cross-section having a transversal arm defining said terminal surface which extends parallel to said extremity flange and having a longitudinal arm connecting the transversal arm to the extremity flange and each head piece covers half of the extremity flange, the head pieces at the upper and lower extremities (90, 92) of each flange plate cover each half of its extremity flange and are in axial symmetry to each other, so that, when two connectors are connected on top of each other, the terminal surface of the head piece at the lower extremity of the flange plate of the upper connector is in contact with the extremity flange at the upper extremity of the flange plate of the lower connector and the extremity flange of the lower extremity of the flange plate of the upper connector is in contact with the terminal surface of the head piece at the upper extremity of the lower connector. a head piece is projecting along the longitudinal direction from each extremity flange, each head piece has an L-shaped cross-section having a transversal arm defining said terminal surface which extends parallel to said extremity flange and having a longitudinal arm connecting the transversal arm to the extremity flange and each head piece covers half of the extremity flange, the head pieces at the upper and lower extremities (90, 92) of each flange plate cover each half of its extremity flange and are in axial symmetry to each other, so that, when two connectors are connected on top of each other, the terminal surface of the head piece at the lower extremity of the flange plate of the upper connector is in contact with the extremity flange at the upper extremity of the flange plate of the lower connector and the extremity flange of the lower extremity of the flange plate of the upper connector is in contact with the terminal surface of the head piece at the upper extremity of the lower connector.