Compositions: coating or plastic – Coating or plastic compositions – Inorganic settable ingredient containing
Reexamination Certificate
2000-12-26
2003-03-25
Wood, Elizabeth D. (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Inorganic settable ingredient containing
C106S819000, C106S822000, C106S823000, C106S638000, C106S713000, C106S724000, C106S728000, C106S810000, C524S002000, C524S003000, C524S004000, C524S005000, C524S006000, C524S007000, C524S008000, C524S080000
Reexamination Certificate
active
06537366
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates generally to compositions and methods of preparing compositions for coloring cementitious materials. More particularly, it relates to compositions and methods for preparing compositions using efflorescence control agents, particulated polymers, and a colorant for coloring cementitious materials.
2. Description of Related Art
Concrete is a mixture of fine and coarse aggregates firmly bound into a monolithic mass by a cementing agent. The cement generally used in forming concrete is Portland cement, although other inorganic hydraulic cements are available, which, upon hydration, form relatively insoluble bonded aggregations of considerable strength and dimensional stability. Portland cement consists mainly of tricalcium silicate and dicalcium silicate. The strength of the cementing agent is a function of the water-cement ratio, and therefore strength will vary widely depending upon the amount of water used. To obtain maximum strength, the water-cement ratio should be kept as low as possible. The aggregates are typically sand and crushed stone or gravel, although crushed clay or cinders can also be used in forming concrete. The formation of concrete is a process by which the voids between the particles of the coarse aggregate are filled by the fine aggregate, and the whole is cemented together by the binding action of the cement.
Concrete is an important building material extensively employed in modern construction because of its strength, permanency, and relatively low cost. The long-term success of concrete in meeting any particular set of conditions depends upon the proper correlation of many factors bearing on the selection and mixing of the materials, the placing of the concrete, and the original design.
Research and development in the science of concrete proportioning has advanced significantly in determining the best and most economical mix for a given condition, i.e., where the concrete may be subject to problems, for example, weathering, vibration, freezing, thawing, and other conditions in any selected environment.
One of the problems associated with concrete is efflorescence. Efflorescence is the deposition of calcium carbonate on the surface of masonry units. Deposition takes place as calcium ions in the cement migrate to the surface of a unit and react with atmospheric carbon dioxide, thereby forming calcium carbonate. The appearance and function of a masonry unit which has effloresced is compromised by the reaction. In preventing the reaction, and therefore maintaining the integrity and aesthetic appearance, chemical admixtures are employed in the formulation.
Stearate-containing compounds are used to prevent efflorescence. These stearate compounds are known in the art as efflorescence control agents (ECAs). Although stearate-containing compounds minimize or eliminate efflorescence, they are also known to adversely affect the durability of concrete. Concrete durability is a function of the totality of the polymerization of the cementitious materials in a mix. Because ECAs hinder polymerization, use of ECAs yield a weaker polymer structure and hence a less durable concrete. Typical ECAs include calcium stearate, zinc stearate, aluminum stearate, among other suitable compounds of stearic acid, salts and derivatives thereof, and mixtures thereof.
Durability of concrete is enhanced by using monomers, polymers, copolymers, and emulsions. Emulsions are generally used for the synthesis of many vinyl and diene polymers and for copolymerization. The polymer produced is in a latex of fine particles, or the latices are coagulated by the addition of chemicals to produce the polymer in a solid form. Typical polymers and copolymers employed include styrene butadiene, polyvinyl acetate, acrylonitrile-butadiene rubber, polyacrylic esters, polyvinylvinylidene, polyvinylidene ester, vinyl chloride, polyethylene-vinyl acetate, polyepoxide, polyurethane, acrylic latex, and mixtures thereof. An example of the use of polymers in concrete is found in U.S. Pat. No. 3,650,784 to Albert which describes a method for improving concrete properties by adding various polymers to fill the pore structure inherent in concrete.
ECAs used in combination with polymers lead to superior concrete properties as described in U.S. Pat. No. 5,922,124 to Supplee, assigned to R&M Chemical Technologies, Inc., the disclosure of which is hereby incorporated by reference as if set forth at length. Improved heat and freeze-thaw durability resulting from reduced efflorescence and stability against ultraviolet light exposure are exemplified in the patent.
The coloring of concrete and other building materials is known. Common concrete colorants are those specified in ASTM C979-86, Standard Specification for Integrally Colored Concrete. The ASTM standards cover the basic requirement for colored and white pigments in powder form to be used as admixtures in concrete for producing integrally colored concrete. The colorants listed in the ASTM specification are generally inorganic pigments which withstand various physical and chemical effects of the intended end use.
The pigments are tested for various properties, including light fastness or resistance to light, alkali resistance, water wettability, atmospheric curing stability, water solubility, and the total sulfates. Inorganic mineral oxides and one specific type of carbon black pigment meet these criteria. Typical pigment types manufactured for coloring concrete include, as set forth in the ASTM standards, synthetic iron oxides, yellows, reds, browns, and black; natural brown iron oxides, chromium oxide green, cobalt blue, and concrete grade carbon black.
U.S. Pat. No. 5,395,442 to Dunton describes a lightweight roof tile with high polymer content, for example, acrylic latex, for adding strength, i.e., durability, with minimally increasing the weight. Organic pigments and inorganic pigments may be used to produce a colored rooftile.
Other patents describe strengthening cementitious veneers, building faces, wall panels, refractory, roofing, and siding articles, and artificial rock by adding polymers. For example, U.S. Pat. No. 4,185,431 to Brownlee employs a polymer emulsion as a wetting agent that is mixed with cement, aggregate, and dry paint pigments for a facing composition. U.S. Pat. No. 4,152,168 to Yano describes a process in which an aqueous colored cement composition containing inorganic particles is applied to the surface of an uncured cement product. U.S. Pat. No. 4,420,525 to Parks describes thin, decorative colored cementitious veneers for walls, floors, and ceilings, and a method of making the veneers. The pigments employed in the colored hydraulic cement mix are natural or inert colors or synthetic materials. Acrylic polymers are optionally included in the mix. U.S. Pat. No. 4,956,013 to Motoki describes a refractory coating composition that includes a hydraulic cement, a re-emulsion type powdery vinyl resin, aluminum hydroxide powder, a carbonate, and lightweight aggregate. In addition to the five components described, pigments as coloring agents may be contained in the composition. U.S. Pat. No. 4,644,719 to Salazar describes a decorative wall panel that includes a reinforced base layer and a patterned top layer composed of Portland cement, sand, and a pigmented binder. U.S. Pat. No. 5,248,338 to Price describes colored marbled concrete that is prepared with concrete, mortar or tile grout dye. U.S. Pat. No. 4,043,826 to Hum describes a process for making artificial rocks by molding a composition that includes cement, a lightweight filler, water, a curing agent for the cement and an acrylic resin latex, and thereafter nonuniformly coloring the hardened rock with cement dyes or pigments. The latex paint used in the artificial rock composition is based on acrylic resins, to which minor amounts of alkyd resins can be included. The colorant material utilized includes ultramarine blue, carbon black, lamp black, and red, yellow and brown oxides.
U.S. Pat. Nos. 5,558,708, 5,951,752,
Color & Chemical Technologies, Inc.
Duane Morris LLP
Wood Elizabeth D.
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