Compositions: coating or plastic – Coating or plastic compositions – Inorganic settable ingredient containing
Reexamination Certificate
1999-09-14
2001-10-09
Green, Anthony (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Inorganic settable ingredient containing
C106S724000
Reexamination Certificate
active
06299679
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to the production and use of cementitious materials which are ready-to-use and wherein the composition of the materials is controlled to retain certain desired properties over a predetermined time period before the composition sets or hardens. The present invention further relates to formulations of components that can be mixed with cementitious material to achieve the desired compositions. Finally, the present invention relates to methods of preparing and using such cementitious materials. Although the present invention broadly relates to cement-based compositions, the invention relates particularly to stucco compositions that are applied to various external surfaces.
BACKGROUND OF THE INVENTION
A variety of different cementitious materials are used in construction including mortars, slags, grouts, concrete and stucco. Often these construction materials are composed of several different components. To facilitate their use, preferably these materials are ready-mixed, and, even more preferably, ready-to-use. The so-called “ready mixed” cementitious materials are those in which most, if not all, of the dry components are premixed at a manufacturing facility or during transport to a job site. In some instances, ready-mixed cementitious materials may also be mixed with the requisite amount of water to carry out the hydration reaction which results in hardening of the cementitious material. In such instances, the material is also “ready-to-use,” i.e., capable of being used without any further additions or mixing.
Although certain cementitious materials, such as cements and mortars for example, are typically delivered ready-to-use, to date a ready-to-use stucco formulation has not been developed. Stucco, or portland cement plaster, is a combination of portland cement-based cementitious material(s) and aggregate (typically sand), mixed with a suitable amount of water to form a plastic mass which will adhere to a surface and harden, preserving any form and texture imposed on it while plastic. As used herein, the term “stucco” refers to portland cement plaster used for coating the exterior surfaces of buildings which falls under ICBOES acceptance criteria AC-11 (Cementitious Exterior Coatings). Stucco is usually applied in one or more coats over metal reinforcement with or without backing. The finish coat is either trowelled, floated, or rough textured. Suitable substrates over which stucco may be applied include, for example, expanded polystyrene (EPS) insulation board, extruded polystyrene insulation foam (XEPS), gypsum sheathing, fiberboard, oriented strand board or plywood, mounted on exterior walls of wood, masonry or steel stud construction. Stucco in the freshly mixed state is a plastic, workable material. It can be applied by hand or machine to conform to any shape.
Stucco is typically applied in three coats. The first coat is called a “base coat” or “scratch coat.” This coat is typically about ⅜″ thick and is left rough to promote good adherence between it and the second coat, which is generally referred to as the “brown coat.” The brown coat is also approximately ⅜ inch thick. The third coat, variously referred to as the “finish coat” or “color coat,” is applied over the second coat. Collectively, the three coats are about ¾ inch thick.
Currently, contractors typically prepare stucco by purchasing bags containing a blend of all the dry ingredients. On site, workers add the necessary water to achieve a mixture with a consistency which is sufficiently fluid so that it can be evenly spread on a wall, while still having enough tackiness that the material adheres to the surface to which it is applied. In some instances, the various components of the stucco composition are purchased individually, mixed on site and then the water added. This approach, however, is inefficient and results in unnecessary labor costs. It would be more efficient to have a ready-to-use stucco prepared at a facility dedicated to preparing stucco.
Another challenge encountered with present stucco compositions and methods are the limitations in controlling the time before the stucco hardens to such an extent that it can no longer be applied. Once water is added to presently available stucco mixes, the stucco must be applied within a limited time period before it dries out and is incapable of being spread. A preferred approach would utilize a trained operator at a central processing facility to add the appropriate additives in order to tailor the period during which the stucco retains sufficient workability in accordance with the time requirements of each job.
Lack of uniformity in stucco preparation at the job site can also be a problem under current methods. Using trained personnel at a central processing facility can significantly reduce this problem.
As noted above, various cementitious materials have been developed which the goal of providing a product having certain improved characteristics. For example, U.S. Pat. No. 5,567,236 describes compositions which can be used to enhance the rheological properties of cement-based materials. However, the additives used to achieve this end are believed to differ from the additives used in the stucco of the present invention.
A variety of patents describe calcium sulfate-based compositions designed to have certain improved characteristics. Examples of such patents include U.S. Pat. Nos. 5,879,446; 5,779,786 and 5,653,797 to Patel or Patel et al.; U.S. Pat. No. 3,869,415 to Williams; U.S. Pat. No. 3,852,083 to Yang; U.S. Pat. No. 3,746,680 to Boricheski; U.S. Pat. No. 3,936,313 to Ericson; U.S. Pat. No. 4,299,790 to Greenberg; U.S. Pat. No. 5,482,551 to Morris et al.; U.S. Pat. No. 5,534,059 to Immordino, Jr.; U.S. Pat. No. 5,718,759 to Stav et al.; and U.S. Pat. No. 4,028,127 to Maske et al. However, the cementitious compositions of the present invention are calcium carbonate and calcium silicate based compositions (approximately ⅓ calcium carbonate and ⅔ calcium silicate) rather than calcium sulfate based compositions. The hydration chemistry, setting process, and mechanical characteristics for these two types of materials is quite different.
SUMMARY OF THE INVENTION
The present invention provides methods for preparing a ready-to-use stucco composition that has a useable life of a desired duration and that can be prepared without the need for alteration at the work site. The useful life of the stucco is at least equal to a pre-application period, a period that includes delivery of the stucco to a job site, and the time necessary to apply the stucco for a particular job. The methods generally involve mixing together at an off-site location a portland cement-containing hydraulic cement, plaster sand, viscosifier, retarder and water to form a stucco composition having predetermined properties. The retarder is present in an amount sufficient to provide the stucco composition with a predetermined useful life during which the stucco is workable. The viscosifier is present in an amount sufficient to retain enough water during the useful life to allow the stucco composition to set after said application period.
Methods for using the stucco compositions of the invention are also provided. These methods typically involve preparing a stucco composition comprising portland cement-containing hydraulic cement, plaster sand, a viscosifier, a retarder and water at a first location, such as a concrete manufacturing or processing facility, for example. The stucco is transferred to a second location (e.g., the worksite). The retarder is present in an amount sufficient to provide the stucco composition with a predetermined useful life during which said stucco composition is workable. The viscosifier is present in an amount sufficient to retain enough water throughout the useful life of the stucco so that it can still harden after the application period. The stucco is placed into a container at the second location, where it is taken from the containers and applied to a surface at t
Green Anthony
Townsend and Townsend / and Crew LLP
Western Mobile New Mexico, Inc.
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