Fiber cement composite materials using cellulose fibers loaded with inorganic and/or organic substances

Abstract

This invention discloses a new technology related to cellulose fiber reinforced cement composite materials using the loaded cellulose fibers. This invention discloses four aspects of the technology: fiber treatment, formulation, method and final product. This technology advantageously provides fiber cement building materials with the desirable characteristics of reduced water absorption, reduced rate of water absorption, lower water migration, and lower water permeability. This invention also impart the final products improved freeze-thaw resistance, reduced efflorescence, reduced chemical dissolution and re-deposition, and improved rot and fire resistances, compared to conventional fiber cement products. These improved attributes are gained without loss in dimensional stability, strength, strain or toughness.

Description

RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 10 / 754,137 filed Jan. 9, 2004 entitled “FIBER CEMENT COMPOSITE MATERIALS USING CELLULOSE FIBERS LOADED WITH INORGANIC AND / OR ORGANIC SUBSTANCE” which is a divisional of U.S. patent application Ser. No. 09 / 969,957 filed on Oct. 2, 2001 entitled “FIBER CEMENT COMPOSITE MATERIALS USING CELLULOSE FIBERS LOADED WITH INORGANIC AND / OR ORGANIC SUBSTANCES”, now U.S. Pat. No. 6,676,744. This application also claims the benefit of U.S. Provisional Application No. 60 / 237,850, filed on Oct. 4, 2000, which is hereby incorporated by reference in its entirety.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates to cellulose fiber reinforced cement composite materials using loaded cellulose fibers, including formulations, methods of manufacture and final products with improved material properties relating to the same. [0004] 2. Description of the Related Art [0005]...

AI Technical Summary

Benefits of technology

"The present invention provides a new technology for making fiber reinforced cement composite materials using loaded cellulose fibers. These fibers are individualized, meaning they are separated from the rest of the material, and they have reduced water absorption, lower water migration, and lower water permeability compared to conventional fiber cement composites. The use of these fibers also results in improved properties such as freeze / thaw resistance, reduced efflorescence, and reduced dissolution and re-deposition of materials. The technology allows for the use of less cellulose fiber, which is a costly ingredient in cement composites, without compromising the key physical properties of strength, stiffness, toughness, and moisture movement. The use of this technology also eliminates the need for expensive hydraulic pressing to crush the cellulose fibers and reduce water permeability in the finished product. Overall, this technology provides a new way to make fiber reinforced cement composite materials with improved properties and durability."

Problems solved by technology

The disadvantage of these products was that the high-density matrix did not allow nailing, and methods of fixing involved pre-drilled holes.

Since silica, even when ground, is much cheaper than cement, and since the autoclave curing time is much less than the air cured curing time, this became a common, but by no means universal manufacturing method.

However, cellulose reinforced cement products are more susceptible to water induced changes, compared to asbestos cement composite materials.

Hence, asbestos reinforced fiber cement products are themselves strong, stiff (also brittle), and could be used in many hostile environments, except highly acidic environments where the cement itself is rapidly attacked chemically.

The wet / dry cycling that asbestos roofing products were subjected to, often caused a few problems, primarily efflorescence, caused by the dissolution of chemicals inside the products when wet, followed by the deposition of these chemicals on the surfaces of the products when dried.

Efflorescence caused aesthetic degradation of roofing products in particular, and many attempts were made to reduce it.

This product is air-cured, since PVA fibers are, in general, not autoclave stable.

The great disadvantage of these products is a very large increase in material and manufacturing process costs.

Thick organic coatings are also expensive, and hydraulic presses are a high cost manufacture step.

However, cellulose fiber cement materials can have performance drawbacks such as lower resistance to water induced damages, higher water permeability, and higher water migration ability (also known as wicking) compared to asbestos cement composite materials.

These drawbacks are largely due to the presence of water conducting channels and voids in the cellulose fiber lumens and cell walls.

As such, conventional cellulose fibers can cause the material to have a higher saturated mass, poor wet to dry dimensional stability, lower saturated strength, and decreased resistance to water damage.

Because the materials are easier to saturate with water, the products also are far more susceptible to freeze / thaw damage.

However, for vertical products, or eaves and soffit linings, and for internal linings, none of these water-induced disadvantages are very relevant.

The primary problem with this technology is increased material and manufacturing cost.

The primary problem with this technology is increased rate, and quantity of water absorption into the product when wet.

However, most of these references are directed to increasing the bond strength of the fibrous material to the cement, rather than addressing the water and moisture related issues of cellulose and / or other fibers.

However, the teachings of the patents above are not specifically directed to the use of partially delignified and individualized fibers, which generally bond well with cement and therefore would not require such treatment methods.

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