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GB2035990A - Fibre Containing Water- Hardenable Masses - Google Patents

Fibre Containing Water- Hardenable Masses Download PDF

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Publication number
GB2035990A
GB2035990A GB7846328A GB7846328A GB2035990A GB 2035990 A GB2035990 A GB 2035990A GB 7846328 A GB7846328 A GB 7846328A GB 7846328 A GB7846328 A GB 7846328A GB 2035990 A GB2035990 A GB 2035990A
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United Kingdom
Prior art keywords
polypropylene
water
monofilaments
sand
mass
Prior art date
Legal status (The legal status 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 status listed.)
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Application number
GB7846328A
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Hawkins & Tipson Ltd
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Hawkins & Tipson Ltd
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Filing date
Publication date
Application filed by Hawkins & Tipson Ltd filed Critical Hawkins & Tipson Ltd
Priority to GB7846328A priority Critical patent/GB2035990A/en
Publication of GB2035990A publication Critical patent/GB2035990A/en
Withdrawn legal-status Critical Current

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Classifications

    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B16/00Use 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
    • C04B16/04Macromolecular compounds
    • C04B16/06Macromolecular compounds fibrous
    • C04B16/0616Macromolecular compounds fibrous from polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • C04B16/0625Polyalkenes, e.g. polyethylene
    • C04B16/0633Polypropylene

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)
  • Road Paving Structures (AREA)
  • Artificial Filaments (AREA)

Abstract

A mix for use in the manufacture of a water-hardenable mass which includes sand, cement and water, comprises a clay free sand and non- fibrilated stretched monofilaments of polypropylene (length between 20 and 30 millimetres), the polypropylene monofilaments being evenly distributed throughout the sand in a random orientation.

Description

SPECIFICATION Water-hardenable Masses This invention relates to the manufacture of water-hardenable masses, to a mix for use in such manufacture, to the manufacture therefrom of articles by pouring, casting or moulding, and to the use of such articles in building construction. A "water-hardenable mass" as used herein is defined as a mixture of inorganic materials, including sand, cement and water, which mixture is capable of setting to a solid coherent mass.
It has been disclosed that the properties, including the flexural strength, of castings and moulding made from Portland cement can be improved by the addition thereto of organic fibres, of which polypropylene fibres are one example.
The prior disclosures concerned with polypropylene fibres describe the addition of pòlypropylene fibres to a wet cement or concrete mix, or alternatively to the ingredients of the mix immediately prior to the addition of water. In the only commercial application of this concept known to the Applicants, polypropylene fibre in the form of fibrillated twine has been added to a cement/sand/water mixture.
Some improvement in the property of the water-hardened mass has been achieved by the incorporation therein of polypropylene fibre in the form of fibrillated twine. The improvement has, however, been a limited one and has not in general justified the expense involved in the use of the polypropylene, and in the complications caused by introducing the fibrillated polypropylene fibres into the mix. It is known that further work on the use of polypropylene in cement products has taken place, and as a result of this work a proposal has been published that layers of stretched fibrillated polypropylene film (i.e. polypropylene mesh) be incorporated in cement mortar mixes.
The present Applicants have found that products having substantially improved flexural strength may be obtained by the use of a waterhardenable mass throughout which non-fibrillated stretched monofilaments of polypropylene having a length within a certain selected range are evenly distributed in a random orientation.
When it is said in this Specification that the monofilaments are "evenly distributed" throughout a mass, it is meant that agglomeration of the monofilaments into balls is avoided and that the monofilaments are distributed essentially individually throughout the mass during the mixing operation. This mixture of the individual monofilaments without agglomeration enables the monofilaments to maintain any orientation which they may adopt on being added to the solid material, with the result that the product formed from the water-hardenable mass will contain monofilaments extending in a multitude of different three-dimensional directions, i.e. the monofilaments have a random orientation.
The Applicants propose to manufacture a water-hardenable mass including polypropylene monofilaments by first effecting an even distribution of the polypropylene monofilaments throughout the sand which is to be mixed with other ingredients to constitute the waterhardenable mass.
In accordance with the present invention therefore there is provided a mix for use in the manufacture of a water-hardenable mass which includes sand, cement and water, the mix comprising a clay-free sand and non-fibrillated stretched monofilaments of polypropylene, the polypropylene monofilaments having a length of between 20 and 30 millimeters, and the polypropylene monofilaments being evenly distributed throughout the sand in a random orientation. The polypropylene monofilaments are present in the mix in a quantity such that they will constitute between 0.2% and 0.3% by weight of the total quantity of the water-hardenable mass.
The mix comprising clay-free sand and polypropylene monofilaments is used to make the water-hardenable mass in a process of which the next step is the addition of water. In accordance with this aspect of the present invention there is provided a method of producing a waterhardenable mass which comprises the steps, in sequence, of mixing together a clay-free sand and non-fibrillated stretched monofilaments of polypropylene which are substantially free of static electricity and which have a length of between 20 and 30 millimetres to obtain a mix in which the polypropylene monofilaments are randomly orientated in and evenly distributed throughout the sand, adding water, effecting further mixing, introducing cement to the wet mix, and continuing mixing to obtain a waterhardenable mass containing the polypropylene monofilaments evenly distributed in a random manner in a quantity of between 0.2% and 0.3% by weight of the total water-hardenable mass.
The process steps set out in the preceding paragraph result in the manufacture of a sand/cement screed containing polypropylene reinforcement in accordance with the present invention. When the present invention is to be applied to the manufacture of a concrete, the process of making the water-hardenable mass includes the further step, after the mixing of the water with the sand and polypropylene monofilaments, of adding aggregate and mixing.
The addition and mixing of the aggregate into the wet mix may be effected either before or after the introduction and mixing of the cement into the wet mix comprising sand, polypropylene monofilaments and water.
According to the present invention there is further provided a water-hardenable mass which is suitable for use as a sand/cement screed and which comprises clay-free sand, non fibrillated stretched monofilaments of polypropylene, Portland cement and water, the polypropylene monofilaments having a length of between 20 and 30 millimetres and being evenly distributed throughout the water-hardenable mass in a quantity of between 0.2% and 0.3% by weight of the total quantity of the water-hardenable mass.
Further in accordance with this aspect of the present invention there is provided a waterhardenable mass which is suitable for use in producing a concrete article by casting, pouring or moulding and which comprises clay-free sand, non-fibrillated stretched monofilaments of polypropylene, Portland cement, aggregate and water, the polypropylene monofilaments having a length of between 20 and 30 millimetres and the polypropylene monofilaments being evenly distributed throughout the water-hardenable mass in a random orientation in a quantity which constitutes between 0.2% and 0.3% by weight of the total quantity of the water-hardenable mass.
A particularly good improvement in the properties of a water-hardened mass formed from a water-hardenable mass in accordance with the present invention has been achieved when the polypropylene monofilaments have a length of the order of 25 millimetres and a diameter of the order of 1 50 microns, the polypropylene monofilaments being present in a total quantity of about 0.25% of the water-hardenable mass.
The present invention will be further understood from the following description of a preferred embodiment thereof which is made by reference to the single figure of the accompanying drawing, which is a flow diagram of a process of producing a water-hardenable mass in accordance with the present invention.
The first step in the process of producing a water-hardenable mass by the method of the present invention is to take one or more reels of polypropylene monofilament. Polypropylene monofilament may have a diameter lying in the range from 100 microns to 250 microns, but in this example the polypropylene monofilament has a diameter of 1 50 microns which falls within a preferred range of between 1 25 microns and 200 microns.
The polypropylene monofilament is drawn from the reel or reels and fed to a cutter which comprises a stationary plate having apertures through which the polypropylene monofilament is passed, and a rotating cutter blade. The speed of rotation of the cutter blade and the rate at which the polypropylene monofilament is fed through the apertures in the plate are so related that lengths of approximately 25 millimetres of polypropylene monofilament are cut successively and allowed to fall freely under gravity into a mixing apparatus (which may be a conventional cement mixer type of apparatus) in which a dry clay-free sand is being continuously agitated.
In performing the process in accordance with the present invention it is important that the lengths of polypropylene monofilament which fall into the agitated sand shall be relatively free of static electricity ("static").
In order to control the static in the cut lengths of monofilament, one of three alternative methods may be employed. An antistatic agent may be added to the granules of polypropylene so that the polypropylene monofilaments which are formed by extrusion contain an antistatic agent in a quantity such as to prevent adhesion of the cut lengths of polypropylene monofilament to one another when these fall into the agitated mass of dry clay-free sand.
Alternatively, the polypropylene monofilament may be coated with an antistatic material immediately before the polypropylene monofilaments are cut to the desired length of 25 millimetres.
A third alternative is for the cut lengths of polypropylene monofilament to be subjected to an electrostatic discharge of opposite polarity to the static on the cut polypropylene monofilaments. Advantageously, the cut lengths of polypropylene monofilament would be passed through the electrostatic discharge immediately prior to mixing with the dry clay-free sand.
As the 25 millimetre lengths of polypropylene monofilament fall into the mixer in which the sand is being continuously agitated, the absence of static in a quantity such as will influence the cut lengths of polypropylene monofilament during their fall or immediately subsequent thereto, results in each length of polypropylene monofilament adopting a position in the sand mass which is entirely random in relation to all the other lengths of polypropylene monofilament.
In consequence, the polypropylene monofilaments of 25 millimetre length become evenly distributed throughout the dry clay-free sand during mixing.
The product obtained at this stage of the process is believed to be an entirely novel product. It is further believed that this step of preparing a mix of dry clay-free sand with selected lengths of polypropylene monofilament ("pp. m-f") evenly distributed in a random manner throughout the dry clay-free sand is an important feature in enabling polypropylene fibre in the form of monofilaments to be used effectively in improving the properties of a building product obtained from a water-hardenable mass.
In order to prepare a water-hardenable mass it is essential for cement, preferably Portland cement, to be mixed with the sand and the polypropylene monofilaments. During such further mixing there is the danger that further static may be induced on the polypropylene monofilaments with the result that the even distribution of the polypropylene monofilaments in the mix is not maintained. In the method of the present invention this possibility is effectively eliminated by making the addition of water to the mix of sand and polypropylene monofilaments the next step, before the cement or any other solid material is added.
It is envisaged that the mix of sand and polypropylene monofilaments may be supplied as such to the site at which the water-hardenable mass is to be used, and water then added with further mixing. The presence of the water will prevent the formation of sufficient static to disturb the even distribution of the polypropylene monofilaments in a random manner when the cement and, optionally, aggregate is added and mixed in at a later stage of the process.
It will be appreciated that it is important for a particular mix of sand and polypropylene monofilaments to be used in formulating the correct or corresponding water-hardenable mass, in order that the quantity of polypropylene monofilaments in the total water-hardenable mass shall be between 0.2% and 0.3% by weight thereof.
Also in accordance with the present invention the process may be a continuous process from the formation of the novel sand/polypropylene monofilament mix to the formation of a building product such as a concrete cladding panel using the method as illustrated in the accompanying drawing with the inclusion ofaggregate in the water-hardenable mass.
Further in accordance with the present invention polypropylene monofilaments substantially as hereinbefore described may be incorporated in a quantity of between 0.2% and 0.3% by weight of the total weight of any known water-hardenable mass in a random manner but evenly distributed throughout the mass, and give a substantial improvement in the properties, and particularly the flexural strength, of the product obtained from that water-hardenable mass.
Such known water-hardenable masses include sand/cement screeds, for example those containing 3 parts of sand to 1 part of Portland cement mixed with 2 part by weight of water, and concretes, for example those having constituents falling within a range from 1 part Portland cement: 2 parts aggregate: 2 parts sand to 1 part Portland cement: 2 parts aggregate: 4 parts sand, the parts being by weight.
In accordance with the present invention the polypropylene monofilaments may be incorporated in a water-hardenable mass used to form steel-reinforced concrete.
Products incorporating 25 millimetre lengths of polypropylene monofilament of 1 50 microns diameter evenly distributed in a random manner in a quantity of 0.25% by weight of the total weight of the water-hardenable mass from which the product is formed have been tested strictly in accordance with BS. 1881/1970. Such tests have been effected in strict comparison with similar mixes which do not include any lengths of polypropylene monofilament and have been undertaken on both concrete (sand, Portland cement and aggregate) and screed (sand and Portland cement) in the form of beams, cylinders and cubes. It has been found that products which contained the lengths of polypropylene monofilament in accordance with the present invention showed an improvement in flexural strength varying from about 100% to more than 200%. It is thought that an improvement of the order of 100% in the flexural strength can be consistently attained by the use of the present invention.
The previously available commercial products which contained polypropylene reinforcement have shown improvements in flexural strength of the order of 30% to 40% only. These commercial products were based on the incorporation into a cement/sand/water mixture of reinforcing fibre elements formed from a stretched and fibrillated polypropylene film (i.e. a polypropylene twine.

Claims (15)

Claims
1. A mix for use in the manufacture of a waterhardenable mass which includes sand, cement and water, the mix comprising a clay-free sand and non-fibrillated stretched monofilaments of polypropylene, the polypropylene monofilaments having a length of between 20 and 30 millimetres, and the polypropylene monofilaments being evenly distributed throughout the sand in a random orientation.
2. A mix according to Claim 1 wherein the polypropylene monofilaments are all of a similar length.
3. A mix according to Claim 1 wherein the length of the polypropylene monofilaments is from 24 to 26 millimetres.
4. A mix according to any one of Claims 1 to 3 wherein the diameter of the polypropylene monofilaments is between 125 and 200 microns.
5. A mix according to any one of Claims 1 to 4 wherein the polypropylene monofilaments are present in such a quantity as to constitute 0.25% by weight of the water-hardenable mass.
6. A method of producing a water-hardenable mass which comprises the steps, in sequence, of mixing together a clay-free sand and nonfibrillated stretched monofilaments of polypropylene which are substantially free of static electricity and which have a length of between 20 and 30 millimetres to obtain a mix in which the polypropylene monofilaments are randomly orientated in and evenly distributed throughout the sand, adding water, effecting further mixing, introducing cement to the wet mix, and continuing mixing to obtain a waterhardenable mass containing the polypropylene monofilaments evenly distributed in a random manner in a quantity of between 0.2% and 0.3% by weight of the total water-hardenable mass.
7. A method according to Claim 6 wherein the mix of polypropylene monofilaments and sand is formed by permitting the polypropylene monofilaments to fall freely under gravity into a mass of the sand while the mass of the sand is being continuously agitated.
8. A method according to Claim 6 wherein aggregate is added to the mix after the addition of the water, and mixed therewith.
9. A method according to any one of Claims 6 to 8 wherein the polypropylene monofilaments are passed through an electrostatic discharge immediately prior to mixing with the sand.
10. A method according to any one of Claims 6 to 8 wherein the polypropylene monofilaments have an antistatic coating thereon.
11. A method according to any one of Claims 6 to 8 wherein the polypropylene monofilaments are formed by extruding polypropylene which contains an antistatic material.
12. A method according to any one of Claims 6 to 11 wherein the polypropylene monofilaments have a length of between 22 and 28 millimetres.
13. A method according to any one of Claims 6 to 11 wherein the polypropylene monofilaments have a length of between 24 and 26 millimetres.
14. A method according to any one of Claims 6 to 13 wherein the polypropylene monofilaments have a diameter of between 125 and 200 microns.
15. A method according to any one of Claims 6 to 14 wherein the polypropylene monofilaments are present in such a quantity as to constitute 0.25% by weight of the water-hardenable mass.
1 6. A water-hardenable mass which is suitable for use as a sand/cement screed and which comprises clay-free sand, non-fibrillated stretched monofilaments of polypropylene, Portland cement and water, the polypropylene monofilaments having a length of between 20 and 30 millimetres and being evenly distributed throughout the water-hardenable mass in a quantity of between 0.2% and 0.3% by weight of the total quantity of the water-hardenable mass.
1 7. A water-hardenable mass which is suitable for use in producing a concrete article by casting, pouring or moulding and which comprises clayfree sand, non-fibrillated stretched monofila ments of polypropylene, Portland cement, aggregate and water, the polypropylene monofilaments having a length of between 20 and 30 millimetres and the polypropylene monofilaments being evenly distributed throughout the water-hardenable mass in a random orientation in a quantity which constitutes between 0.2% and 0.3% by weight of the total quantity of the water-hardenable mass.
1 8. A water-hardenable mass according to either of Claims 16 and 1 7 wherein the polypropylene monofilaments have a length of the order of 25 millimetres and a diameter of the order of 1 50 microns, and wherein the polypropylene monofilaments constitute about 0.25% by weight of the total quantity of the water-hardenable mass.
1 9. The use in building construction or in the manufacture of an article intended for use in building construction of a water-hardenable mass as claimed in any one of Claims 16 to 1 8 or as produced by a method as claimed in any one of Claims 6 to 1 5.
GB7846328A 1978-11-28 1978-11-28 Fibre Containing Water- Hardenable Masses Withdrawn GB2035990A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB7846328A GB2035990A (en) 1978-11-28 1978-11-28 Fibre Containing Water- Hardenable Masses

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Application Number Priority Date Filing Date Title
GB7846328A GB2035990A (en) 1978-11-28 1978-11-28 Fibre Containing Water- Hardenable Masses

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0225036A1 (en) * 1985-10-23 1987-06-10 MTA Természettudományi Kutato Laboratoriumai Process for producing reinforced bodies, especially precast building units
WO1989001916A1 (en) * 1987-08-26 1989-03-09 Oy Partek Ab A self-leveling slurry screed, and a dry product for use in preparing it
AT394547B (en) * 1988-03-21 1992-04-27 Basta Walter Hydraulically settable or bound building material, for example concrete, mortar, cement/sand mixtures, etc., containing polypropylene fibres as aggregate
AT395241B (en) * 1988-11-11 1992-10-27 Basta Walter Process for recycling plastic scrap, mixing-in machine used for this purpose, fibres, building materials and fibre-reinforced concrete
WO2006038225A3 (en) * 2004-10-06 2006-08-31 Saurabh S Patwa A reinforcing fiber for concrete, a flexible concrete and a method to prepare the concrete
CN112592115A (en) * 2020-12-17 2021-04-02 浙江波威新材料科技有限公司 Polypropylene modified concrete and preparation method thereof

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0225036A1 (en) * 1985-10-23 1987-06-10 MTA Természettudományi Kutato Laboratoriumai Process for producing reinforced bodies, especially precast building units
WO1989001916A1 (en) * 1987-08-26 1989-03-09 Oy Partek Ab A self-leveling slurry screed, and a dry product for use in preparing it
AT394547B (en) * 1988-03-21 1992-04-27 Basta Walter Hydraulically settable or bound building material, for example concrete, mortar, cement/sand mixtures, etc., containing polypropylene fibres as aggregate
AT395241B (en) * 1988-11-11 1992-10-27 Basta Walter Process for recycling plastic scrap, mixing-in machine used for this purpose, fibres, building materials and fibre-reinforced concrete
WO2006038225A3 (en) * 2004-10-06 2006-08-31 Saurabh S Patwa A reinforcing fiber for concrete, a flexible concrete and a method to prepare the concrete
CN112592115A (en) * 2020-12-17 2021-04-02 浙江波威新材料科技有限公司 Polypropylene modified concrete and preparation method thereof

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