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Polystyrene blocks use expanded foam beads to form a solid material that is lightweight, easily cut and has enough strength to be used as concrete forms. During the forming process, the foam beads are expanded to fill a form. The design of the form dictates the finished size and shape of the polystyrene block. A mold can be designed to accommodate a wide variety of shapes for a wide variety of uses. Molded polystyrene blocks are used for carving lightweight sculptures, to form insulated concrete walls and for insulating exterior building components.
Carving lightweight sculptures out of expanded polystyrene foam blocks for decorative purposes or parade floats requires the correct tools to ensure the blocks retain enough strength to hold their shape after installation. Two types of carving tools will sculpt polystyrene blocks. Hot wire tools use a superheated wire to cut quickly through the foam to create intricate details on the surface of the block. Sharp cutting tools also have the ability to create intricate details, but have a tendency to break the foam if the material gets thin. Another type of polystyrene block does not need to be carved and has the strength required to be used with concrete.
Polystyrene concrete form blocks have a solid outer core with a series of hollow inner cavities that allow concrete to flow through a series of installed blocks. Proper installation techniques and the correct materials are required to ensure the blocks remain in place when the concrete fills the voids in the blocks. During installation, heavy wire is weaved between the sections of the block to hold them in place. The manufacturers of polystyrene blocks supply wire spacing information to ensure the blocks do not fail while concrete fills the forms. When the concrete cures, the blocks are left in place to provide insulation for the finished building.
Tightly-compressed polystyrene blocks or sheets are applied to the walls and interior sides of roofs to provide insulation between the interior and exterior sides of a building. Specialty adhesives are used to bond the blocks to metal and wood wall materials. Adhering to the proper installation methods ensures the bond between the surface of the polystyrene blocks and the wall material remains strong long after installation. Proper installation includes freeing the wall material of debris, removing loose foam beads from the block and applying the correct amount of adhesive to the wall material.