Method of making extruded fiber reinforced cement matrix composites
AssigneeNorthwestern University
InventorsSurendra P. Shah, Yixin Shao, Shashi Marikunte
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Abstract
An extruded fiber reinforced cement matrix composite having substantially improved tensile strength with strain hardening behavior and substantially improved tensile strain, and improved flexural properties in three-point bending. The composite is made by mixing cement, water, water soluble binder, and relatively short, discontinuous reinforcing fibers, preferably short poly vinyl alcohol fibers, to provide an extrudable mixture; then extruding the mixture to shape, and curing the cement.
Claims18
A method of making a fiber reinforced cement matrix composite, comprising:
- dispersing discontinuous reinforcing fibers comprising synthetic hydrophilic polymeric material in aqueous slurry to form a dispersion of wetted reinforcing fibers,
- then mixing hydraulic cement, water, and water soluble binder with said dispersion including controlling the weight ratio of water to cement in the range of 0.2 to 0.4 to provide an extrudable mixture having the fibers dispersed uniformly therein,
- extruding the mixture to shape through a die orifice that imparts a shape to said mixture and is effective to compress and shear said mixture to improve bonding between said fibers and said cement, and
- curing the cement, wherein an extruded and cured composite is formed exhibiting increased tensile strength properties as compared to a cast composite of similar composition and strain hardening behavior when stressed in tension with at least 1% tensile strain.
A method of making a fiber reinforced cement matrix composite, comprising:
- dispersing discontinuous reinforcing fibers comprising synthetic hydrophilic polymeric material in aqueous slurry to form a dispersion of wetted reinforcing fibers,
- then mixing hydraulic cement, water, and water soluble binder with said dispersion including controlling the weight ratio of water to cement in the range of 0.2 to 0.4 to provide an extrudable mixture having the fibers dispersed therein,
- extruding the mixture to shape through a die orifice that imparts a shape to said mixture and is effective to compress and shear said mixture to improve bonding between said fibers and said cement with the discontinuous fibers preferentially aligned in a direction of extrusion of the extruded shape, and
- curing the cement, wherein an extruded and cured composite is formed exhibiting increased tensile strength properties as compared to a cast composite of similar composition and strain hardening behavior when stressed in tension with at least 1% tensile strain.
A method of making a fiber reinforced cement matrix composite having improved tensile properties in all directions, comprising:
- dispersing discontinuous reinforcing fibers comprising synthetic hydrophilic polymeric material in aqueous slurry to form a dispersion of wetted reinforcing fibers,
- then mixing hydraulic cement, water, and water soluble binder with said dispersion including controlling the weight ratio of water to cement in the range of 0.2 to 0.4 to provide an extrudable mixture having the fibers dispersed uniformly therein,
- extruding the mixture to shape through a die orifice effective to compress and shear said mixture to improve bonding between said fibers and said cement, and
- curing the cement, wherein an extruded and cured composite is formed exhibiting increased tensile strength properties as compared to a cast composite of similar composition and strain hardening behavior when stressed in tension with at least 1% tensile strain.
A method of making a fiber reinforced cement matrix composite having improved tensile properties in an extrusion direction with strain hardening behavior, and improved flexural properties in three-point bending, comprising:
- dispersing discontinuous reinforcing fibers comprising synthetic hydrophilic polymeric material in aqueous slurry to form a dispersion of wetted reinforcing fibers,
- then mixing hydraulic cement, water, and water soluble binder with said slurry dispersion including controlling the weight ratio of water to cement in the range of 0.2 to 0.4 to provide an extrudable mixture having the fibers dispersed uniformly therein,
- extruding the mixture to shape through a die orifice that imparts a shape to said mixture and is effective to compress and shear said mixture to improve bonding between said fibers and said cement with the discontinuous fibers preferentially aligned in the extrusion direction of the extruded shape to an extent to increase relative tensile strength properties in that direction as compared to a transverse direction, and
- curing the cement, wherein an extruded and cured composite is formed exhibiting increased tensile strength properties as compared to a cast composite of similar composition and strain hardening behavior when stressed in tension with at least 1% tensile strain.
A method of making an extruded fiber reinforced cement matrix composite having improved tensile strength of at least about 750 psi in an extrusion direction, strain hardening behavior with at least 1% tensile strain and improved flexural properties in three-point bending transverse to an extrusion direction, comprising:
- dispersing discontinous reinforcing fibers comprising polyvinyl alcohol and silica fume powder in aqueous slurry to form a dispersion of wetted reinforcing fibers,
- then mixing hydraulic cement, water, and water soluble binder with said dispersion to provide an extrudable mixture having the fibers uniformly dispersed therein,
- extruding the mixture to shape through a die orifice that imparts a shape to said mixture with the discontinuous fibers preferentially aligned in the extrusion direction of the extruded shape to an extent to increase relative tensile properties in that direction as compared to a transverse direction thereof, and
- curing the cement.
Dependencies are inferred from the claim text.