Continuous mixer and method of mixing reinforcing fibers with cementitious materials

A method for preparing cement composite slurry comprising:

• feeding a liquid stream comprising water, into a continuous slurry mixer through a liquid stream inlet and feeding a stream of a dry cementitious powder into the continuous slurry mixer to form a cementitious slurry, said slurry mixer having a horizontally or vertically mounted impeller;
• passing the cementitious slurry from the slurry mixer into a single pass horizontal fiber-slurry continuous mixer and passing a stream of reinforcement fibers into the horizontal fiber-slurry continuous mixer and mixing the cementitious slurry and the reinforcement fibers to form a fiber-slurry mixture,
• the horizontal fiber-slurry continuous mixer comprising
• an elongated mixing chamber defined by a horizontal (typically cylindrical) housing having an interior cylindrical side wall,
• at least one fiber inlet port to introduce reinforcement fibers through the interior cylindrical side wall directly into the chamber in a first feed section of the horizontal housing, said reinforcement fibers comprising fiberglass, polymeric materials, polypropylene, polyethylene, polyvinyl alcohol, carbon, graphite, aramid, ceramic, steel or a combination thereof, and
• at least one cementitious slurry inlet port to introduce cementitious slurry mixture through the interior cylindrical side wall directly into the chamber in a second feed section of the horizontal housing,
• a fiber-slurry mixture outlet port at a second discharge end section of the horizontal housing to discharge the fiber reinforced cementitious slurry mixture produced by the mixer, and
• a venting port to remove any air introduced into the mixing chamber from raw material feed,
• a rotating central horizontally oriented shaft mounted within the elongated mixing chamber traversing from one end of the fiber-slurry mixer to another end of the fiber-slurry mixer,
• a plurality of mixing and conveying paddles mounted on the horizontally oriented shaft of the fiber-slurry mixer at regular intervals and different circumferential locations, the paddles rotated about the horizontally oriented shaft within the horizontal housing, the paddles extending radially from a location on the shaft, the paddles comprising a pin engaged to a paddle head, the pin pivotally engaged to the horizontally oriented shaft and/or the paddle head to permit pivotal rotation of the paddle head relative to the respective location on the horizontally oriented shaft, wherein the plurality of paddles are arranged to mix the reinforcement fibers and cementitious slurry and move the cementitious slurry and reinforcement fibers being mixed to the fiber-slurry mixture outlet;
• wherein the horizontally oriented shaft is externally connected to a drive mechanism and a drive motor, to accomplish shaft rotation when the fiber-slurry mixer is in operation;
• wherein the cementitious slurry and reinforcement fibers are mixed in the mixing chamber of the horizontal fiber-slurry mixer for an average mixing residence time of about 5 to about 240 seconds while the rotating paddles apply shear force, wherein the central horizontally oriented shaft rotates at 30 to 450 RPM during mixing, to the fiber-slurry mixture to produce a uniform fiber-slurry mixture;
• discharging the fiber-slurry mixture from the fiber-slurry mixer laterally relative to the horizontal housing through an opening in the side wall of the horizontal housing into and through the fiber-slurry mixture outlet port,
• wherein the dry cementitious powder comprises at least one of Portland cement, calcium aluminate cements (CAC), calcium sulfoaluminate cements (CSA), geopolymers, magnesium oxychloride cements (sorel cements), and magnesium phosphate cements.