Blended fibers in an engineered cementitious composite

#Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57.

#Embodiments of the present disclosure relate to cementitious composite materials incorporating reinforcement fibers with improved properties developed primarily for use in the building and construction industry.

#Fiber reinforced cementitious composite materials have been widely used in building construction. Cellulose fibers, in particular, have been used to reinforce various fiber cement building products because they impart favorable properties to the building product. Moreover, cellulose fibers have a unique microstructure with unique physical and mechanical properties that are suitable for the Hatschek process, the preferred commercial process for manufacturing fiber cement sheets and panels. For example, the micro-fibrils in cellulose fibers help to build an effective filtration system to catch the fine particles in the fiber cement slurry to form a thin fiber-particle film during the Hatschek process. The micro-fibrils also branch out with the branches functioning as anchors in the cured fiber cement composite thereby enhancing the bonding at the interface between the fibers and cementitious matrix.

#FIGS. 1A-1B are photos of two different types of synthetic fibers after the Parr bomb test according to certain embodiments of the present disclosure.

#FIG. 2A-2B are photos illustrating examples of synthetic fibers in a cement matrix according to certain preferred embodiments before the autoclave cycle under a microscope.

#FIG. 3A-3C are various views of the synthetic fiber shown in FIGS. 2A-2B in the fiber composite matrix.

#Disclosed herein are fiber cement articles reinforced with a fiber blend pre-selected to provide the fiber cement articles with improved mechanical and/or chemical properties. Also disclosed herein are fiber blends comprised of synthetic and natural fibers at pre-selected ratios for reinforcing cementitious composite materials and methods for manufacturing. Also disclosed herein are synthetic and cellulose fiber blends adapted to reinforce cementitious composite articles manufactured by the Hatschek process and autoclave cured. Also disclosed herein are fiber reinforced cement formulations that include cellulose pulp and synthetic fibers in a ratio selected to provide a building material with improved water absorption characteristics and the same or improved mechanical properties as compared to equivalent building materials reinforced with predominantly or all cellulose fibers.

#One of the challenges in incorporating synthetic reinforcing fibers, such as polypropylene (PP) fibers, in fiber cement composite materials is that synthetic fibers, unlike cellulose fibers, are not configured to catch sufficient amount of fine particles in fiber cement slurry to form a thin fiber cement film during the Hatschek process. Additionally, most synthetic fibers like PP fibers will disintegrate at autoclave temperatures. As such, while synthetic fibers have been incorporated in fiber cement articles, the synthetic fibers are not successfully added in sufficient quantities as a substitute for substantial amounts of cellulose fibers, especially not in fiber cement panels and sheets that are typically manufactured by the Hatschek process and autoclave cured. The inventors have developed certain fiber reinforced composite material compositions that incorporate fiber blends comprising synthetic and cellulose fibers selected to reinforce cementitious articles manufactured by the Hatschek process and cured at autoclave temperatures without deleterious effects.

#Fiber Blends