Inflatable construction apparatus

A modular base element useable to form an envelope of a inflatable and deflatable device which is fluid-tight and, when inflated, is employed as a reusable formwork support for building construction, said modular base element (10) comprising:

• an elongated sheet or membrane (12) being made from a flexible fluid-tight material which is resistant to ultraviolet radiation, abrasion and traction and can be welded, vulcanized, adhered or sewed;
• said sheet or membrane (12) having four scallops (18), respectively located at corners of said sheet or membrane (12)
• said scallops being mutally symmetrical with respect to an axis of longitudinal symmetry and an axis of transverse symmetry of said sheet or membrane;
• each scallop of said scallops contained respectively within each of four quarters of said sheet or membrane as defined by the intersection of said axis of longitudinal symmetry and said axis of transverse symmetry of said sheet or membrane;
• a shape of each scallop being a hyperbola whose two asymtotes would respectively be parallel to each of said axis of longitudinal symmetry and said axis of transverse symmetry of said sheet or membrane;
• wherein said modular base element is formed as a U-shaped rib with a semicylindrical surface whose convexity is turned toward an outside of said inflatable and deflatable device when assembled, with two flat extensions (16) tangent to the semicylindrical surface along two longitudinal edges thereof, each of said two flat extensions (16) being composed of a section of said sheet or membrane included between a line of tangence with respect to said semicylindrical surface, a first part of a contour of two scallops of said four scallops (18) between which said section is formed, and a long side of the sheet or membrane.