Composite permanent block-form for reinforced concrete construction and method of making same

A block for use in reinforced concrete construction having a top, bottom and four sides, voids extending through the blocks from the top to the bottom, adapted to align with voids in similar blocks when the blocks stacked on top of one another to form cavities for the reception of concrete slurry, the block having a central core of foamed plastic with said voids formed therein, and having a continuous sheath formed on four sides of a porous, inorganic material.

The block of claim 11 wherein the glass based material comprises glass grit in a porous structure.

The block of claim 12 wherein the foamed plastic constitutes polyurethane.

The block of claim 13 wherein the walls of the voids are formed of circular tubes of cardboard having their outer surfaces adhered to the polyurethane.

The method of making construction blocks having central voids formed therein for the reception of concrete comprising:

• forming a rectangular sheath consisting of four rectangular slabs of a porous non-combustible material having their edges joined to one another so as to form an open, four-sided box;
• supporting thin walled hollow tubes within the spaced enclosed by the sheath so that the axes of the tubes extend parallel to the walls of the sheath;
• and forming a volume of self-expanding foamed plastic between the interior of the sheath and the exterior surface of the tubes so that the plastic adheres to both the sheath and the tubes.