The present invention relates generally to structural or building components and in particular to mastic compositions, methods of forming same, and composite structural panels utilizing mastic compositions as well as methods and apparatus for forming such panels.
In the past, various mastic compositions, methods of forming them, and composite structural panels utilizing mastic compositions as well as methods and apparatus for forming composite structural panels have been disclosed, but while each had certain advantageous features, none contained all or even most of the features desirable for forming or use of the composite panels as a structural or building component.
U.S. Pat. No. 3,021,291 discloses mixing expandable polystyrene beads with a cementitious slurry, using a gas to form a cellular material with voids therein, and, after setting or curing, heating to expand the beads which are intended to fill voids. U.S. Pat. Nos. 3,630,820 and 3,697,366 each disclose that closed-cell expanded polystyrene beads, when mixed in a cementitious slurry, rise or float to the top of the slurry so as to make it impossible to attain a homogeneous mixture. In these disclosures, expanded polystyrene beads are shredded to open the cells of the normally closed-cell beads thereby to permit them to absorb slurry into their shredded open cells which overcomes the flotation problem and ensures a homogeneous mix of shredded open-cell beads with the slurry. U.S. Pat. No. 3,598,672 describes mixing expanded polystyrene beads with an epoxy resin, admixing glass fibers which adhere to the surfaces of the beads, subjecting this mixture to pressure to effect setting thereof and then separating the beads coated with glass fibers for use in forming other products.
U.S. Pat. No. 2,633,439 discloses a composite structural panel with a core of spiral wood shavings and gypsum plaster facing layers or walls with the edges of the shavings embedded in the opposite wall surfaces, but each of the spiral wood shavings has a central aperture to provide free passage of air between cells and to the exterior of the panel. U.S. Pat. No. 2,892,339 shows a honeycomb core structural panel formed in its entirety of molded gypsum material. One face and the honeycomb structure are integrally formed, then cured, and then pressed into the other face to form the panel. One notch is provided in one wall edge of each individual honeycomb cell to permit the circulation of air throughout the core of the assembled honeycomb structure, in which wire mesh and/or fibers may be used for reinforcement. U.S. Pat. No. 3,249,659 discloses the application of a thin layer of foam-forming polyurethane resin to opposite surfaces of two webs of paper facing material which are brought into contact with opposite faces of a honeycomb core and the assembly then heated to effect foaming of the resin. Holes are provided in the honeycomb walls interconnecting each individual honeycomb cell to permit air circulation throughout the entire honeycomb core.