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WO2006038225A2 - A reinforcing fiber for concrete, a flexible concrete and a method to prepare the concrete - Google Patents

A reinforcing fiber for concrete, a flexible concrete and a method to prepare the concrete Download PDF

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Publication number
WO2006038225A2
WO2006038225A2 PCT/IN2005/000334 IN2005000334W WO2006038225A2 WO 2006038225 A2 WO2006038225 A2 WO 2006038225A2 IN 2005000334 W IN2005000334 W IN 2005000334W WO 2006038225 A2 WO2006038225 A2 WO 2006038225A2
Authority
WO
WIPO (PCT)
Prior art keywords
concrete
mortar
cement
fiber
reinforcing fiber
Prior art date
Application number
PCT/IN2005/000334
Other languages
French (fr)
Other versions
WO2006038225B1 (en
WO2006038225A3 (en
Inventor
Saurabh S. Patwa
Original Assignee
Patwa Saurabh S
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Patwa Saurabh S filed Critical Patwa Saurabh S
Publication of WO2006038225A2 publication Critical patent/WO2006038225A2/en
Publication of WO2006038225A3 publication Critical patent/WO2006038225A3/en
Publication of WO2006038225B1 publication Critical patent/WO2006038225B1/en

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
    • E04C5/07—Reinforcing elements of material other than metal, e.g. of glass, of plastics, or not exclusively made of metal
    • E04C5/073—Discrete reinforcing elements, e.g. fibres
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B16/00—Use of organic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of organic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B16/04—Macromolecular compounds
    • C04B16/06—Macromolecular compounds fibrous
    • C04B16/0675—Macromolecular compounds fibrous from polymers obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
    • C04B20/10—Coating or impregnating
    • C04B20/12—Multiple coating or impregnating
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
    • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
    • D01F8/06—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyolefin as constituent
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
    • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
    • D01F8/14—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyester as constituent
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
    • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
    • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
    • D06M15/21—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D06M15/227—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of hydrocarbons, or reaction products thereof, e.g. afterhalogenated or sulfochlorinated

Definitions

  • the present invention relates to a reinforcing fiber for concrete, flexible concrete / mortar and a method of preparing the same.
  • cement moldings external walls of architectures inner walls of tunnels etc are constructed with mortars, concrete and the like.
  • these moldings have comparatively large fragility. Therefore, recently fibers such as steel fibers, polyvinyl alcohol resins, polyolefin resins are used for cement moldings.
  • polyvinyl fibers used in the cement hydrolyze at high temperature under an alkaline condition as cement is alkaline in nature and heat is evolved during preparation of the concrete, the polyvinyl fibers get deteriorate resulting in inferior quality of the concrete. Further, polyvinyl fibers used for preparing concrete absorb water. Therefore, more water requires preparing a cement concrete.
  • the polyolefin resin fibers have few hydrophilic radicals in the molecular structure that it affects the adhesion of the fiber to the cement matrixes. Further, the finite polyolefin fibers having length less than 5m form fiber masses called fiber ball from their shapes and also difficult to disperse evenly in the cement.
  • flexible continuous cement mortar/matrix are made by setting fibers in cement paste.
  • Fibers are generally mixed at last in the concrete or mortar containing cement in a transit mixer and allowed to set after casting.
  • fibers are mixed in the concrete or with the water in the drum after adding aggregates and cement and allowed to set after casting.
  • polysilicate matrix being made from cement it is less likely that the fibers set completely in the polysilicate matrix made on setting of cement with hydration and therefore, deterioration of concrete occurs at a relatively quicker rate resulting in the formation of discontinuities, micro cracks, capillaries / voids leading to shrinkage cracks and lesser concrete strength and flexibility.
  • WO2004039744A1/EP150173 discloses a use of polypropylene fiber in the cement concrete to increase the crack resistance, strength.
  • the surface of the polypropylene fibers require to be oxidized and fluorination treatment for better bonding with the cement. Further, the polypropylene fibers have less tensile stress.
  • An object of the present invention is to provide a reinforcing fiber having good tensile strength.
  • object of the present invention is to provide a flexible cement concrete and method to prepare the flexible cement concrete. Furthermore object of the present invention is to overcome the problems of the prior art.
  • a reinforcing fiber for concrete/mortar comprises a polyester fiber as a core for improving tensile strength; an alkali-resistant material coated over the polyester fiber having profiled surface; an active agent coated on the alkali-resistant polymer material.
  • the profiled surface of the reinforcing fiber is a ribbed, semi- perforated, corrugated, embossed surface or the like.
  • the reinforcing fibers have diameter between 8 micron and 30 micron preferably 20 micron.
  • the diameter of the core is 5-15 micron and the thickness of the polypropylene coating over the polyester is 7.5-12.5 microns.
  • Said fiber has a length between 3mm to 30mm preferably between 6mm and 19mm.
  • Said alkali-resistant polymer material is polypropylene, carbon, nylon or the polymers having high resistance to the alkaline conditions.
  • Said active coating is silicon oil or equivalent.
  • a flexible concrete/mortar comprising water, the reinforcing fibers of the first embodiment cement or cementitious material, plasticizers, sand, coarse aggregates, in a suitable proportion wherein said fibers are set in an elongated form in the concrete produces compressive force in the concrete and provides better bonding/adhesion improving flexibility, continuity and strength of the concrete/mortar.
  • the cement concrete can be set with or without steel.
  • a method of preparing a flexible concrete or mortar comprising steps of mixing and stirring reinforcing fibers of the first embodiment with water; adding and stirring said mixture to cement to form a paste; adding and stirring plasticizer in a predetermined quantity; adding and stirring sand, fine aggregates and coarse aggregates; and adding and stirring predetermined quantity of water; mixing and stirring air-entering agents; setting the mixture with or without steel to form a flexible concrete/mortar having reinforcing fibers in stretched form.
  • said fibers may be elongated by pre-heating in boiling water before adding cement during preparation of the concrete/mortar.
  • Accelerators and plasticizers can be mixed for allowing setting concrete/mortar fast for keeping fibers in stretched condition.
  • Said cement is 53 grade or above grade cement for quick setting of the concrete.
  • a cement or cementitious material comprises a mixture of the cement and the reinforcing fibers of the first embodiment.
  • Fig 1 shows a reinforcing fiber having polyester at core and semi perforated alkali-resistant material coating.
  • Fig 4 shows magnified view of steel-free flexible concrete/mortar
  • Fig 5 shows effect of the Live Load on the Steel-Free flexible concrete/mortar.
  • the present invention provides reinforcing fiber and a concrete/mortar having reinforcing fiber and a method of preparing the concrete/mortar.
  • the reinforcing fiber (100) according to the preferred embodiment of the present invention is shown in Fig 1 to 3 include polyester fiber of a suitable diameter forming a core (110) coated with a desired profile of alkali-resistant polymer material (120) and then coated with active coating (not shown).
  • the polyester fiber of the reinforcing fiber has a circular cross section having a diameter between 5 micron and 15 micron.
  • the polyester core may be triangular, star or square cross section. It is known in the technology that polyester has better tensile strength. Therefore, polyester fiber core improves the tensile strength of the reinforcing fiber.
  • monofilament polyester fiber is coated with the alkali- resistant polymer material and extrudes through a die to obtain a desired profile of the coated alkali-resistant polymer material.
  • the desired profile of alkali-resistant polymer material coated over the polyester fiber is embossed, corrugated, ribbed, semi-perforated or the like that increase the contact surface area of the reinforcing fiber.
  • the alkali-resistant polymer material includes polypropylene homo-polymer, polypropylene copolymer, carbon nylon and the polymer materials having high resistance to the alkali.
  • polyester fiber is coated with the polypropylene material, as it is inexpensive.
  • the polypropylene material coated over the polyester fiber have ribbed, coating is 7.5 to 15 microns.
  • the polypropylene coated fiber is then coated with the active agent such as silicon oil or the like.
  • the silicon oil causes better dispersion of the reinforcing fiber in the cement or cementitious material.
  • the active agent has a thickness between 0.01 and 0.5 micron.
  • the reinforcing fiber obtained is then cut to obtain desired length of the fiber. Then end of the fibers may be coated with the polypropylene to avoid contact of the cement with the polyester fiber.
  • the reinforcing fiber has overall effective diameter between 5 and 30 micron and length between 3mm and 30mm.
  • preferable length for the reinforcing fiber is between 6mm and 19mm and the diameter of the reinforcing fiber is 20 micron.
  • the desired length of the reinforcing fiber depends upon the average voids generated between the coarse aggregates to keep the fiber mostly straight on setting within the polysilicate of the concrete.
  • the reinforcing fiber of the present invention has better tensile stress and dispersion property.
  • Fig 1 shows a reinforcing fiber (100) as per present invention comprising a core of the polyester (110) and coated with the alkali resistant polymer material (120) having semi-perforated surface (122) and active agent (not shown) to increase the surface area.
  • Fig 2 shows a reinforcing fiber (100) as per present invention comprising a core of polyester (110) and coated with the alkali resistant polymer material (120) having ribbed surface (124) and active agent (not shown).
  • Fig 3 shows a reinforcing fiber (100) as per present invention comprising a core of polyester (110) coated with the alkali-resistant polymer material (120) having embossed surface (126) and active agent (not shown).
  • the present invention provides a flexible concrete/mortar (200) comprising water, the reinforcing fibers of the first embodiment cement or cementitious material, plasticizers, sand preferably zone Il sieved sand, coarse aggregates, in a suitable proportion wherein said fibers are set in an elongated form in the concrete produces compressive force in the concrete and provides better bonding/adhesion improving flexibility, continuity and strength of the concrete/mortar.
  • the flexible concrete can be set with or without steel.
  • the fibers provide more contact surface area and disperse in the concrete/mortar evenly due to the coating of the active agent like silicon oil.
  • the flexible concrete/mortar with the reinforcing fibers according to the present invention is resistant to earth quake and other resultant stress to an increased degree. Further, the Flexi-Crete fibers in the flexible concrete/mortar prevent segregation of concrete/mortar and formation of plastic shrinkage cracks thereby enhancing durability, toughness, and flexibility of the concrete/mortar.
  • the concrete set without steel is shown in Fig 4 and 5 (Referring hereinafter as steel free flexible concrete).
  • the Micro-elongation of the reinforcing fibers due to heat of hydration or by pre-heating in boiling water or with any other suitable method generate small compressing forces (F) in a direction as shown in Fig 5.
  • Fig 5 shows when there is a load on the steel-free flexible concrete/mortar (220). The load applied on the steel-free concrete tries to push the concrete down while the compressive forces (F) push the concrete above as shown in Fig 5. This results in nullification of the stress on the concrete providing a flexible, tough, durable and crack free concrete/mortar (230) without the steel-reinforcement.
  • the proportion of the reinforcing fiber mixed in the concrete/mortar is between 150-200 gm/m 3 of the concrete i.e. 150-200 gm/m 3 of the concrete. Further, the proportion of the reinforcing fibers can be altered in the concrete/mortar depending on the requirement.
  • a method of preparing a flexible concrete/mortar according to the present invention includes the step of: mixing and stirring reinforcing fibers with predetermined quantity of water; adding and stirring said mixture to cement to form a paste; mixing and stirring plasticizer in a predetermined quantity; adding and stirring sand, fine aggregates and coarse aggregates; adding and stirring predetermined quantity of water; adding and stirring air-entering agents; adding and allowing setting of the paste mixture with or without steel to form a flexible concrete/mortar.
  • the reinforcing fibers are getting elongated due to heat of hydration and get contracted back as concrete/mortar cool down on setting brings the matrerials more closer producing a less porous concrete.
  • the reinforcing fibers get micro-elongated due to heat of hydration during concreting process.
  • the reinforcing fibers may be elongated with preheating in boiling water prior to mixing if desired more micro pre-stressing.
  • the purpose of the cement concrete/mortar in the present invention covers all sort of cement products such as wall, flooring, finishing mortar, waterproof concrete, slate roof materials as buildings, pavement for example roads, airstrips, road materials such as road signs, cement pipes, etc wherever cement or cement concrete/mortar requires.
  • the cement used in the concrete/mortar or flexible cement is 53 grade or above for fast setting. Accelerators and plasticizers are used to set concrete/mortar very fast keeping the fibers in stretched condition.
  • the cement used in the concrete includes Portland cement, blast furnace cement silica cement, fly ash cement alumina cement and the like.
  • the aggregates used in both steel-free flexible concrete and the flexible concrete include sand and coarse aggregate.
  • the sand includes river sand, sea sand, pit sand, silica sand, glass sand, iron sand, ash, artificial sand and the like.
  • the coarse aggregate includes gravel, ballast, crushed stone, slag, various artificial lightweight aggregates and the like.
  • the properties of the reinforcing fibers used for the examples are as follows:
  • test slabs were made from the conventional concrete and Flexible concrete using the method as described in the specification.
  • the dimensions of the test slab used for the experiment were made from the conventional concrete and Flexible concrete using the method as described in the specification.
  • the results of the tests shows: 1.
  • the flexible concrete retains the concrete merit of high compressive strength, improves the toughness index and texturing capacity of the cement and therefore, improves the break resistance and tensile strength. Consequently, the reinforcing fibers offset the fragility that crudely presence in the conventional or ordinary concrete.
  • the durability of the flexible concrete was improved. All splitting resistance, barrier 'property and resistance to impact were improved. Freeze resistance was improved and lose of strength was reduced about 50%. Furthermore, the reinforcing fiber posses the merits of high acid and alkali resistance and resistance to ageing. The reinforcing fibers in the flexible concrete dispersed evenly and absorb the internal stress of the concrete that brought by temperature difference and wet difference and controls microcosmic crack of the flexible concrete. Thereby greatly improves the durability of the concrete.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Ceramic Engineering (AREA)
  • Structural Engineering (AREA)
  • Textile Engineering (AREA)
  • Architecture (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Civil Engineering (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)
  • Artificial Filaments (AREA)
  • Chemical Or Physical Treatment Of Fibers (AREA)
  • Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)

Abstract

The present invention provides a reinforcing fiber, a flexible concrete prepared using the reinforcing fiber and a method for preparing the concrete. The reinforcing fibers of the present invention comprises a polyester fiber as a core for improving tensile strength; an alkali-resistant material coated over the polyester fiber having profiled surface; an active agent coated on the alkali- resistant polymer material for better dispersion of the said reinforcing fiber in the concrete/mortar. The reinforcing fibers in the flexible concrete improve the flexibility, continuity and strength of the concrete.

Description

A REINFORCING FIBER FOR CONCRETE, A FLEXIBLE CONCRET AND A METHOD TO PREPARE THE CONCRETE1
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reinforcing fiber for concrete, flexible concrete / mortar and a method of preparing the same.
BACKGROUND AND PRIOR ART OF THE INVENTION
Conventionally, cement moldings, external walls of architectures inner walls of tunnels etc are constructed with mortars, concrete and the like. However these moldings have comparatively large fragility. Therefore, recently fibers such as steel fibers, polyvinyl alcohol resins, polyolefin resins are used for cement moldings.
However, as specific gravity of the steel fiber is high, cement paste including steel fibers are difficult to carry at the project site and entrapped. Moreover, the steel fibers get rusty.
The polyvinyl fibers used in the cement hydrolyze at high temperature under an alkaline condition as cement is alkaline in nature and heat is evolved during preparation of the concrete, the polyvinyl fibers get deteriorate resulting in inferior quality of the concrete. Further, polyvinyl fibers used for preparing concrete absorb water. Therefore, more water requires preparing a cement concrete.
The polyolefin resin fibers have few hydrophilic radicals in the molecular structure that it affects the adhesion of the fiber to the cement matrixes. Further, the finite polyolefin fibers having length less than 5m form fiber masses called fiber ball from their shapes and also difficult to disperse evenly in the cement.
Further, flexible continuous cement mortar/matrix are made by setting fibers in cement paste. In the preparing process, Fibers are generally mixed at last in the concrete or mortar containing cement in a transit mixer and allowed to set after casting. Alternatively, fibers are mixed in the concrete or with the water in the drum after adding aggregates and cement and allowed to set after casting. However, in such polysilicate matrix, being made from cement it is less likely that the fibers set completely in the polysilicate matrix made on setting of cement with hydration and therefore, deterioration of concrete occurs at a relatively quicker rate resulting in the formation of discontinuities, micro cracks, capillaries / voids leading to shrinkage cracks and lesser concrete strength and flexibility.
WO2004039744A1/EP150173 discloses a use of polypropylene fiber in the cement concrete to increase the crack resistance, strength. However, the surface of the polypropylene fibers require to be oxidized and fluorination treatment for better bonding with the cement. Further, the polypropylene fibers have less tensile stress.
SUMMARY OF THE PREESENT INVENTION:
An object of the present invention is to provide a reinforcing fiber having good tensile strength.
Further object of the present invention is to provide a flexible cement concrete and method to prepare the flexible cement concrete. Furthermore object of the present invention is to overcome the problems of the prior art.
According to the first embodiment of the present invention, a reinforcing fiber for concrete/mortar comprises a polyester fiber as a core for improving tensile strength; an alkali-resistant material coated over the polyester fiber having profiled surface; an active agent coated on the alkali-resistant polymer material.
The profiled surface of the reinforcing fiber is a ribbed, semi- perforated, corrugated, embossed surface or the like. The reinforcing fibers have diameter between 8 micron and 30 micron preferably 20 micron. The diameter of the core is 5-15 micron and the thickness of the polypropylene coating over the polyester is 7.5-12.5 microns. Said fiber has a length between 3mm to 30mm preferably between 6mm and 19mm. Said alkali-resistant polymer material is polypropylene, carbon, nylon or the polymers having high resistance to the alkaline conditions. Said active coating is silicon oil or equivalent.
According to the second embodiment of the present invention, a flexible concrete/mortar comprising water, the reinforcing fibers of the first embodiment cement or cementitious material, plasticizers, sand, coarse aggregates, in a suitable proportion wherein said fibers are set in an elongated form in the concrete produces compressive force in the concrete and provides better bonding/adhesion improving flexibility, continuity and strength of the concrete/mortar.
Advantageously, the cement concrete can be set with or without steel. According to the third embodiment of the present invention, a method of preparing a flexible concrete or mortar comprising steps of mixing and stirring reinforcing fibers of the first embodiment with water; adding and stirring said mixture to cement to form a paste; adding and stirring plasticizer in a predetermined quantity; adding and stirring sand, fine aggregates and coarse aggregates; and adding and stirring predetermined quantity of water; mixing and stirring air-entering agents; setting the mixture with or without steel to form a flexible concrete/mortar having reinforcing fibers in stretched form.
According to the present invention, said fibers may be elongated by pre-heating in boiling water before adding cement during preparation of the concrete/mortar.
Accelerators and plasticizers can be mixed for allowing setting concrete/mortar fast for keeping fibers in stretched condition. Said cement is 53 grade or above grade cement for quick setting of the concrete.
According to the fourth embodiment of the present invention, a cement or cementitious material comprises a mixture of the cement and the reinforcing fibers of the first embodiment.
BRIEF DESCRIPTION OF DRAWINGS
Fig 1 shows a reinforcing fiber having polyester at core and semi perforated alkali-resistant material coating.
Fig 2 shows a reinforcing fiber having polyester at core and ribbed alkali-resistant material coating. Fig 3 shows a reinforcing fiber having polyester at core and embossed alkali-resistant material coating.
Fig 4 shows magnified view of steel-free flexible concrete/mortar
Fig 5 shows effect of the Live Load on the Steel-Free flexible concrete/mortar.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
The present invention provides reinforcing fiber and a concrete/mortar having reinforcing fiber and a method of preparing the concrete/mortar.
The reinforcing fiber (100) according to the preferred embodiment of the present invention is shown in Fig 1 to 3 include polyester fiber of a suitable diameter forming a core (110) coated with a desired profile of alkali-resistant polymer material (120) and then coated with active coating (not shown).
The polyester fiber of the reinforcing fiber has a circular cross section having a diameter between 5 micron and 15 micron. Alternatively, The polyester core may be triangular, star or square cross section. It is known in the technology that polyester has better tensile strength. Therefore, polyester fiber core improves the tensile strength of the reinforcing fiber. For preparing a reinforcing fiber as per the present invention, monofilament polyester fiber is coated with the alkali- resistant polymer material and extrudes through a die to obtain a desired profile of the coated alkali-resistant polymer material.
The desired profile of alkali-resistant polymer material coated over the polyester fiber is embossed, corrugated, ribbed, semi-perforated or the like that increase the contact surface area of the reinforcing fiber. The alkali-resistant polymer material includes polypropylene homo-polymer, polypropylene copolymer, carbon nylon and the polymer materials having high resistance to the alkali. Preferably, polyester fiber is coated with the polypropylene material, as it is inexpensive. The polypropylene material coated over the polyester fiber have ribbed, coating is 7.5 to 15 microns.
The polypropylene coated fiber is then coated with the active agent such as silicon oil or the like. The silicon oil causes better dispersion of the reinforcing fiber in the cement or cementitious material. The active agent has a thickness between 0.01 and 0.5 micron. The reinforcing fiber obtained is then cut to obtain desired length of the fiber. Then end of the fibers may be coated with the polypropylene to avoid contact of the cement with the polyester fiber.
The reinforcing fiber has overall effective diameter between 5 and 30 micron and length between 3mm and 30mm. Advantageously, preferable length for the reinforcing fiber is between 6mm and 19mm and the diameter of the reinforcing fiber is 20 micron. However, the desired length of the reinforcing fiber depends upon the average voids generated between the coarse aggregates to keep the fiber mostly straight on setting within the polysilicate of the concrete.
The reinforcing fiber of the present invention has better tensile stress and dispersion property.
Fig 1 shows a reinforcing fiber (100) as per present invention comprising a core of the polyester (110) and coated with the alkali resistant polymer material (120) having semi-perforated surface (122) and active agent (not shown) to increase the surface area.
Fig 2 shows a reinforcing fiber (100) as per present invention comprising a core of polyester (110) and coated with the alkali resistant polymer material (120) having ribbed surface (124) and active agent (not shown).
Fig 3 shows a reinforcing fiber (100) as per present invention comprising a core of polyester (110) coated with the alkali-resistant polymer material (120) having embossed surface (126) and active agent (not shown).
The present invention provides a flexible concrete/mortar (200) comprising water, the reinforcing fibers of the first embodiment cement or cementitious material, plasticizers, sand preferably zone Il sieved sand, coarse aggregates, in a suitable proportion wherein said fibers are set in an elongated form in the concrete produces compressive force in the concrete and provides better bonding/adhesion improving flexibility, continuity and strength of the concrete/mortar. The flexible concrete can be set with or without steel. The fibers provide more contact surface area and disperse in the concrete/mortar evenly due to the coating of the active agent like silicon oil. This results in reduction in the discontinuities of cement binder in the concrete/mortar / mortar matrix as the reinforcing fibers provide continuity and flexibility to the concrete/mortar thereby producing the flexible concrete/mortar of the present invention, and enhances the strength of the concrete/mortar. Due to the above properties, the flexible concrete/mortar with the reinforcing fibers according to the present invention is resistant to earth quake and other resultant stress to an increased degree. Further, the Flexi-Crete fibers in the flexible concrete/mortar prevent segregation of concrete/mortar and formation of plastic shrinkage cracks thereby enhancing durability, toughness, and flexibility of the concrete/mortar.
The concrete set without steel is shown in Fig 4 and 5 (Referring hereinafter as steel free flexible concrete). The Micro-elongation of the reinforcing fibers due to heat of hydration or by pre-heating in boiling water or with any other suitable method generate small compressing forces (F) in a direction as shown in Fig 5. Fig 5 shows when there is a load on the steel-free flexible concrete/mortar (220). The load applied on the steel-free concrete tries to push the concrete down while the compressive forces (F) push the concrete above as shown in Fig 5. This results in nullification of the stress on the concrete providing a flexible, tough, durable and crack free concrete/mortar (230) without the steel-reinforcement.
The proportion of the reinforcing fiber mixed in the concrete/mortar is between 150-200 gm/m3 of the concrete i.e. 150-200 gm/m3 of the concrete. Further, the proportion of the reinforcing fibers can be altered in the concrete/mortar depending on the requirement.
A method of preparing a flexible concrete/mortar according to the present invention includes the step of: mixing and stirring reinforcing fibers with predetermined quantity of water; adding and stirring said mixture to cement to form a paste; mixing and stirring plasticizer in a predetermined quantity; adding and stirring sand, fine aggregates and coarse aggregates; adding and stirring predetermined quantity of water; adding and stirring air-entering agents; adding and allowing setting of the paste mixture with or without steel to form a flexible concrete/mortar. The reinforcing fibers are getting elongated due to heat of hydration and get contracted back as concrete/mortar cool down on setting brings the matrerials more closer producing a less porous concrete.
The reinforcing fibers get micro-elongated due to heat of hydration during concreting process. Alternatively, the reinforcing fibers may be elongated with preheating in boiling water prior to mixing if desired more micro pre-stressing.
Further, the fibers of the present invention can be mixed with the cement to before the final packing in twin-screw mixer or with any suitable method to produce the cement mix (hereinafter referred as flexible cement). The preferable proportional weight of the reinforcing fiber mixed in the cement to produce the flexible cement is 125gms/50kg of cement. Further, the proportion of the reinforcing fiber can be changed in the flexible cement depending on the requirement.
The purpose of the cement concrete/mortar in the present invention covers all sort of cement products such as wall, flooring, finishing mortar, waterproof concrete, slate roof materials as buildings, pavement for example roads, airstrips, road materials such as road signs, cement pipes, etc wherever cement or cement concrete/mortar requires. The cement used in the concrete/mortar or flexible cement is 53 grade or above for fast setting. Accelerators and plasticizers are used to set concrete/mortar very fast keeping the fibers in stretched condition. Further, the cement used in the concrete includes Portland cement, blast furnace cement silica cement, fly ash cement alumina cement and the like. The aggregates used in both steel-free flexible concrete and the flexible concrete include sand and coarse aggregate. The sand includes river sand, sea sand, pit sand, silica sand, glass sand, iron sand, ash, artificial sand and the like. The coarse aggregate includes gravel, ballast, crushed stone, slag, various artificial lightweight aggregates and the like.
The following example explains the efficiency of the reinforcing fibers of the present invention:
Example 1
The tests were conducted to compare the conventional concrete/mortar and the flexible concrete/mortar prepared according to the present invention.
The properties of the reinforcing fibers used for the examples are as follows:
Figure imgf000011_0001
Figure imgf000012_0001
Other materials used to prepare concrete/mortar are as follows:
1. Cement : Jinmao P.032.5
2. Sand : River sand
3. Stone: Granite 5mm - 25mm
4. Coal ash: Grade 1
5. Additives NF 6 high efficiency
The conventional concrete and the flexible concrete were prepared using the quantity as shown in Table A
Table 1
Figure imgf000012_0002
The test slabs were made from the conventional concrete and Flexible concrete using the method as described in the specification. The dimensions of the test slab used for the experiment
Dimensions: 914mm X 610mm X 19mm Test 1
The compressive strength of Axes and Elastic modulus under static pressure are tested according to "Experimental method about the Performance of the Common concrete's mixture" as described in GB/T50080-2002. Test results are shown in Table B
Test 2-
The slunt, Gas content are tested by "Experimental method about the Performance of the Common concrete's mixture" as described in GB/T50080-2002. Test results are shown in Table B
Test 3
The barrier property and freeze resistance, shrinkage rate are tested according to "Experimental Method on the Long term Properties and the Durability of the Common concrete's mixture" described in GBJ82- 1985. Test results are shown in Table C
Test 4
The splitting and dry shrinkage resistances are tested according to "The Test on the Performance of the Reinforced Fiber concrete" described in American Concrete Institution ACI - 544. Test results are shown in Table B
Test 5
The Impact resistance of concrete tested according to "The Test on the Performance of the Reinforced Fiber concrete" described in American Concrete Institution ACI - 544. Test results are shown in Table B
Table B
Figure imgf000014_0001
Table C
Figure imgf000014_0002
The results of the tests shows: 1. The flexible concrete retains the concrete merit of high compressive strength, improves the toughness index and texturing capacity of the cement and therefore, improves the break resistance and tensile strength. Consequently, the reinforcing fibers offset the fragility that crudely presence in the conventional or ordinary concrete.
2. The durability of the flexible concrete was improved. All splitting resistance, barrier 'property and resistance to impact were improved. Freeze resistance was improved and lose of strength was reduced about 50%. Furthermore, the reinforcing fiber posses the merits of high acid and alkali resistance and resistance to ageing. The reinforcing fibers in the flexible concrete dispersed evenly and absorb the internal stress of the concrete that brought by temperature difference and wet difference and controls microcosmic crack of the flexible concrete. Thereby greatly improves the durability of the concrete.

Claims

1. A reinforcing fiber for concrete/mortar comprising:
a. a polyester fiber as a core for improving tensile strength;
b. an alkali-resistant material coated over the polyester fiber having profiled surface;
c. an active agent coated on the alkali-resistant polymer material.
2. A reinforcing fiber for concrete/mortar as claimed in claim 1 wherein said profiled surface is a ribbed, semi-perforated, corrugated, embossed surface or the like.
3. A reinforcing fiber for concrete/mortar as claimed in claim 1 wherein the fiber have diameter between 8 micron and 30 micron preferably 20 micron.
4. A reinforcing fiber for concrete/mortar as claimed in claim 1 wherein diameter of the polyester fiber core is 5-15 micron and the thickness of the polypropylene coating over the polyester is 7.5-12.5 microns.
5. A reinforcing fiber for concrete/mortar as claimed in claim 1 and 4 wherein said fiber has a length between 3mm to 30mm preferably between 6mm and 19mm.
6. A reinforcing fiber for concrete/mortar as claimed in claim 1 wherein said alkali-resistant polymer material is polypropylene carbon, nylon or the polymers having high resistance to the alkaline conditions.
7. A reinforcing fiber for concrete/mortar as claimed in claim 1 wherein said active coating is silicon oil or equivalent.
8. A flexible concrete/mortar or mortar comprising water, the reinforcing fibers as claimed in claims 1-7, cement or cementitious material, plasticizers, sand, coarse aggregates, in a suitable proportion wherein said fibers are set in elongated form in the concrete produces compressive force in the concrete and improves bonding/adhesion flexibility, continuity and strength of the concrete/mortar.
9. A flexible concrete/mortar as claimed in claim 8 the proportion of the reinforcing fiber mixed in the concrete/mortar is between 150-200 gm/m3 of concrete.
10. A flexible concrete/mortar as claimed in claim 8 wherein said concrete can be set with or without steel.
11. A method of preparing a flexible concrete/mortar or mortar comprising steps of:
a. mixing and stirring Flexi Crete fiber as claimed in claims 1-7 with water
b. adding and stirring said mixture to cement to form a paste;
c. adding and stirring plasticizer in a predetermined quantity;
d. adding and stirring sand, fine aggregates and coarse aggregates; and
e. adding and stirring predetermined quantity of water; f. adding and stirring air-entering agents;
g. setting the mixture with or without steel to form a flexible concrete/mortar having reinforcing fibers in stretched form.
12. A method as claimed in claim 9 further comprising mixing and stirring of accelerators and plasticizers for allowing to set concrete/mortar/mortar/matrix quickly for keeping fibers in stretched condition.
13. A method as claimed in claim 9 wherein said cement is 53 grade or above grade cement for quick setting of concrete.
14. A method as claimed in claim 9 may comprises a step of preheating the reinforcing fibers before adding cement.
15. A cement or cementitious material comprising the reinforcing fiber as claimed in claims 1 to 7.
PCT/IN2005/000334 2004-10-06 2005-10-06 A reinforcing fiber for concrete, a flexible concrete and a method to prepare the concrete WO2006038225A2 (en)

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ES2325011A1 (en) * 2008-02-20 2009-08-21 Juan Antonio Rovira Soler 33,5% Bar including fibre-reinforced polymers for concrete reinforcement
EP3572594A1 (en) * 2018-05-24 2019-11-27 Solidian GmbH Reinforcing rod with alkali-resistant coating
US20200131769A1 (en) * 2018-10-30 2020-04-30 King Saud University Multi-leg fiber reinforced concrete
CN112142407A (en) * 2020-09-27 2020-12-29 嘉华特种水泥股份有限公司 Fiber toughness well cementing material
CN114031346A (en) * 2021-11-15 2022-02-11 深圳市纳路特建材科技有限公司 Anti-cracking cement mortar and application thereof
CN114315268A (en) * 2021-12-17 2022-04-12 杭州鼎昇建材有限公司 High-strength emergency concrete and preparation method thereof
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DK695688D0 (en) * 1988-12-14 1988-12-14 Danaklon As FIBERS AND MATERIALS CONTAINING THE SAME
FR2661903B1 (en) * 1990-05-11 1992-08-07 Rhone Poulenc Fibres NEW CEMENT COMPOSITION BASED ON PORTLAND CEMENT.
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ES2325011A1 (en) * 2008-02-20 2009-08-21 Juan Antonio Rovira Soler 33,5% Bar including fibre-reinforced polymers for concrete reinforcement
WO2009103839A1 (en) * 2008-02-20 2009-08-27 Vialobra S.L. Bar including fibre-reinforced polymers for concrete reinforcement
ES2325011B1 (en) * 2008-02-20 2010-06-01 Juan Antonio Rovira Soler 33,5% BAR BASED WITH REINFORCED POLYMERS WITH FIBERS FOR REINFORCING THE CONCRETE.
EP3572594A1 (en) * 2018-05-24 2019-11-27 Solidian GmbH Reinforcing rod with alkali-resistant coating
WO2019224038A1 (en) * 2018-05-24 2019-11-28 Solidian Gmbh Reinforcing rod having an alkali resistant jacket
US20200131769A1 (en) * 2018-10-30 2020-04-30 King Saud University Multi-leg fiber reinforced concrete
CN112142407A (en) * 2020-09-27 2020-12-29 嘉华特种水泥股份有限公司 Fiber toughness well cementing material
CN114031346A (en) * 2021-11-15 2022-02-11 深圳市纳路特建材科技有限公司 Anti-cracking cement mortar and application thereof
CN114315268A (en) * 2021-12-17 2022-04-12 杭州鼎昇建材有限公司 High-strength emergency concrete and preparation method thereof
CN115075407A (en) * 2022-07-26 2022-09-20 科洛结构自防水技术(深圳)有限公司 Construction process for replacing traditional concrete post-cast strip with functions of temperature suppression, crack resistance and deep sealing
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