To the above thoroughly blended dry formulation, there is added about 800 to 850 pounds of water, and the resultant aqueous slurry is uniformly blended prior to trowel application of the slurry over a suitable absorptive base for receiving plaster, such as a base wall of National Gypsum Company's Kal Kore board. EXAMPLE IĪccording to the present invention, a wall or ceiling veneer plaster dry formulation is prepared as follows: _ The veneer plaster, according to the present invention, includes calcium sulfate beta hemihydrate, fine silica sand and a melamine-formaldehyde-sodium bisulfite polymer dispersant, additives as necessary for controlling setting times, a minor amount of a water retention aid and a minor amount of a trowel working aid. These and other objects and advantages of the invention will be more readily apparent when considered in relation to the preferred embodiments as set forth in the following specification. It is a still further object to provide a high strength, abrasion resistant veneer plaster with good troweling characteristics which results in a true white plastered wall. It is a still further object to provide a high strength veneer plaster having improved abrasion resistance. It is a further object to provide a novel veneer plaster having a compressive strength of substantially greater than 3,000 psi. It is an object of this invention to provide a novel improved veneer plaster. The invention further involves thoroughly mixing this preferred plaster formulation with water at a ratio of about 42 grams of water to 100 grams of the plaster formulation, and applying this aqueous mixture to a suitable plaster base to form a veneer plaster coat about 1/16- to 3/32-inch thick. The present invention involves a novel plaster formulation which preferably includes about 1,800 pounds of calcium sulfate beta hemihydrate, 200 pounds of fine silica sand, 2.7 pounds of set stabilizer, 1 pound of set retarder, 3.6 pounds of melamine-formaldehyde-sodium bisulfite polymer dispersant, 0.9 pound of superabsorbent polymer water retention aid and 0.7 pound of poly (methyl vinyl ether/maleic acid) trowel working aid. Accordingly, a formulation is desired for producing a veneer plaster having in excess of 3,000 psi compressive strength, substantially improved abrasion resistance and also a suitably and consistent white color. They normally require about 65 grams of water per 100 grams of dry plaster formulation.Ī veneer plaster, of unknown composition, has been sold having a compressive strength of about 3,000 psi. These veneer plasters commonly have a compressive strength of about 1,200-1,400 psi, when tested according to ASTM-C472-90a, and have a penetration of over 0.05 inch after 200 cycles of brushing with a 3M Granule Embedding Testing Machine with a 5-pound loaded wire brush. Veneer plasters are commonly employed to form wall surfaces, involving the application of a plaster coat, about 1/16-inch thick, over suitable plaster receptive boards, previously applied to a wall framework. This invention relates to a novel, improved veneer plaster having improved strength and abrasion resistance and more particularly to a plaster formulation incorporating novel dispersants and fine aggregates to reduce mixing water demand.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |