Prestressed composite load-bearing slab

Claim 1

A COMPOSITE, LOAD-BEARING SLAB MADE UP OF A PAIR OF STRONG, DENSE FACE ELEMENTS AND A CORE OF LOW-DENSITY: EACH FACE ELEMENT COMPRISING A RELATIVELY THIN, PRECAST SHEET OF PORTLAND CEMENT CONCRETE OF LOAD BEARING QUALITY, REINFORCED WITH PRESTRESSED WIRES EXTENDING BETWEEN THE AREAS OF SUPPORT OF THE SLAB; AND A LOW-DENSITY CORE CLEARLY DIFFERENTIATED FROM SAID FACES, OF SUFFICIENT THICKNESS TO SPACE THE FACE ELEMENTS AT OPTIML DISTANCE FROM THE NEUTRAL AXIS OF THE SLAP; EACH OF THE FACES OF THE CORE HAVING ADHESIVELY CEMENTED THERETO ONE OF THE FACE ELEMENTS, THE LINE OF ADHESION BEING SHARP AND WELL-DEFINED AND OF LOADTRANSFERRING QUALITY, THE AREAS OF CONTACT BETWEEN THE CORE AND THE FACE ELEMENTS BEING SUBSTANTIALLY CONTINUOUS OVER THE ENTIRE PORTION IN CONTACT; WHEREIN THE THICKNESS OF THE LOWER FACE ELEMENT INCREASES FROM A THICKNESS OF 1/10 THE SLAB THICKNESS, AT THE END, TO ABOUT 1/4 THE SLAB THICKNESS AT A DISTANCE OF 1 1/2 TIMES SLAB THICKNESS FROM THE END AND THEN DECREASES TO 1/10 THE SLAB THICKNESS AT A DISTANCE OF 5 1/2 TIMES SLAB THICKNESS FROM THE END.