Provided herein are various flexible sheet-like substrates that are lightweight, rupture or burst resistant, and suitable for use in constructing a variety of structures used in fluid-containment, especially gas containment, and other applications, and the processes by which such composites can be fabricated. In the most general case, the composites of this disclosure are comprised of a woven textile fabric to which has been laminated a flexible film. Two principal embodiments are disclosed: a first embodiment without a reinforcing layer, and a second embodiment with a structurally robust, bias-oriented reinforcing layer, preferably interposed between the fabric and the film.