EP0499572B1 - Apparatus for cutting up fibre string into fibre cuts and dosing the latter into a concrete mixture - Google Patents

Apparatus for cutting up fibre string into fibre cuts and dosing the latter into a concrete mixture Download PDF

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Publication number
EP0499572B1
EP0499572B1 EP92610009A EP92610009A EP0499572B1 EP 0499572 B1 EP0499572 B1 EP 0499572B1 EP 92610009 A EP92610009 A EP 92610009A EP 92610009 A EP92610009 A EP 92610009A EP 0499572 B1 EP0499572 B1 EP 0499572B1
Authority
EP
European Patent Office
Prior art keywords
fibre
string
concrete
cutter
cutting
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.)
Expired - Lifetime
Application number
EP92610009A
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German (de)
English (en)
French (fr)
Other versions
EP0499572A1 (en
Inventor
Iwer Dall
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Skako AS
Original Assignee
Skako AS
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 Skako AS filed Critical Skako AS
Publication of EP0499572A1 publication Critical patent/EP0499572A1/en
Application granted granted Critical
Publication of EP0499572B1 publication Critical patent/EP0499572B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28C—PREPARING CLAY; PRODUCING MIXTURES CONTAINING CLAY OR CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28C5/00—Apparatus or methods for producing mixtures of cement with other substances, e.g. slurries, mortars, porous or fibrous compositions
    • B28C5/40—Mixing specially adapted for preparing mixtures containing fibres
    • B28C5/404—Pre-treatment of fibres

Definitions

  • the invention relates to an apparatus according the introductory part of claim 1.
  • fibres of various kinds have for many years advantageously been used to increase the tensile strength of concrete.
  • the fibres are of plastic, e.g. polypropylene, there are additionally obtained other significant advantages.
  • the plastic fibres thus prevent visible shrinkage cracks by limiting the development of micro-cracks.
  • concrete normally undergoes a volume reduction causing formation of micro-cracks.
  • the presence of the plastic fibres entails that this crack-formation is counteracted, and that the concrete develops its full potential strength and impermeability.
  • the fibres change the intrinsic structure of the concrete, and a crack-free product is obtained which does not call for provision of traditional shrinkage reinforcement nets.
  • the fibres In the high-dosing area, where 10-20 kg fibres/m 3 cement bound material are added, the fibres additionally impart a decided reinforcing effect to the material, whereby its tensile strength, tenacity and energy of rupture are significantly increased.
  • the fibre reinforced object When the fibre reinforced object is loaded in excess of the bearing capacity of the unreinforced material, countless evenly distributed stable micro-cracks are formed, but the presence of the fibres entails that this crack-formation does not lead to fracture until at a significantly higher load.
  • the even distribution of the micro-cracks necessary for obtaining the above advantageous properties is, however, contingent on a correspondingly even distribution of the plastic fibres.
  • These fibres have very small density as compared with e.g. the aggregates stone and sand, and besides, the fibres take up negligible space in comparison with the total concrete mass. Consequently, it has been extremely difficult to achieve a sufficiently even distribution of the fibres by means of the commonly used dosing method where the fibres are merely batch-wise poured manually into the concrete mixture.
  • An apparatus according to the introductory part of claim 1 is known from Swiss patent No. 460 620, comprising a programmed control unit for controlling the feeding speed of the fibre, so that the fibre is added to the concrete mixture during wet mixing.
  • Swiss patent No. 460 620 also suggests a method where the fibre cut is added during dry mixing.
  • the cutter is positioned at a level above the mixer, whereby the fibre cut by itself in finely distributed form sifts down into the mixer through an air duct.
  • this duct there is a gate which normally bars communication from the concrete mixer up to the cutter, which is hereby spared attacks by dust and moisture which could otherwise rise through the air duct and attack the cutter. The gate is then only opened when the desired quantity of fibre cuts is to be added to the mixture.
  • the cutter can be positioned above a conveyor or an air duct between the cutting machine and the mixer. This allows the cutting proper to take place at some distance from the mixing process, which may often be advantageous.
  • the cutting of the fibre string and a supply thereof may e.g. be placed in another room or in another storey.
  • the fibre string proper is normally wound into spools which in a suitable number are placed in a magazine from where the cutter itself normally fetches the strings.
  • the apparatus may comprise at least two exchangeable magazines, so that one can be filled while the other operates.
  • the concrete mixer may be connected to several complete apparatus which are used in turn.
  • the apparatus additionally comprises a sensor for sensing the feeding speed of the fibre string and a control unit for regulating in dependence of the signal from the sensor the feeding speed, so that the desired quantity of fibre cuts is added to the mixture in the desired even flow.
  • Fig. 1 shows a complete apparatus for mixing concrete and adding a predetermined fibre cut portion to the mixture.
  • the raw materials used for this mixture are in this case stored in four silos which in order of succession from the left is a cement silo 1, an additive silo 2, a water silo 3 and an aggregate silo 4.
  • These siloes which are all of conventional kind, are each closable by a gate, and are furthermore each separate one connected to a concrete mixer 5 via pipe conduits which in the figure are merely indicated by a dotted line.
  • the concrete mixer is further connected to a cutting arrangement which in its entirety is designated by the reference numeral 6 and which serves to cut fibre string into fibre cut and feed the latter to the concrete mixer in the manner further described in the following.
  • Fig. 2 shows, partly in section, the cutting arrangement 6 shown in fig. 1 in a larger scale, and the same arrangement is also shown schematically in fig. 3.
  • the complete arrangement is, as best seen from fig. 2, positioned in a closed cabinet 7, which via an air duct 8 is connected to the concrete mixer 5, of which only a segment is shown.
  • the arrangement comprises a cutter 9, consisting of a press roller 10 and a cutter head 11.
  • Fig. 4 shows a segment of this cutter in a larger scale in the process of cutting a fibre string 12 to fibre cuts.
  • the fibre string 12 is wound a couple of turns around a row of radially positioned knives 12 positioned in equally spaced relationship along the periphery of the cutter head 11.
  • the press roller 10 is urged with a suitable pressure against the cutter head 11, whereby the immermost one of the turns of the fibre string is cut through by the knives 13 and drops down between the latter as fibre cut 14. Since the fibre string 12, as mentioned, has been wound several turns around the cutter head 11 the latter will itself automatically attract the fibre string in step with the cutting up.
  • the cutter 9, as shown in fig. 2 and 3, is simultaneously provided with several strings at a time. These strings have been wound into a number of spools 15 accomodated in a magazine 16 which is part of the complete cutting arrangement 6. From the spools 15 the fibre strings have been passed e.g. through eyes 17 (fig. 3) or over reels 18 (fig. 2) for guiding the strings on their way to the cutter 9, which, as mentioned, by itself attracts the strings as needed. In the air duct 8 there is a gate 19 which is opened by dosing, but is normally closed to prevent moisture and dust from the mixing process from rising and damaging the cutter 9 or other parts of the cutting arrangement 6. Sensors 20 serve to sense the feeding speed of the fibre strings.
  • the concrete mixer 5 When the concrete is to be mixed, the concrete mixer 5 is first supplied with the prescribed quantity of aggregates in the form normally of stone and sand from the silo 4, a dry mixing hereby taking place, whereafter the cement from the silo 1 is dosed under continued dry mixing. Finally, additives and water from the silos 2 and 3, respectively, are added, and after wet mixing of the entire concrete mixture it is now ready for discharge from the concrete mixer 5.
  • plastic fibres is capable of considerably improving the material properties of the finished concrete i.a. by distributing any crack-formations into a finely meshed net of unharmful micro-cracks.
  • the precondition for optimal exploitation of this effect is, however, precisely that the fibres are distributed very evenly in the concrete mixture. Is this not so, the finished concrete will easily become inhomogeneous. In some areas the concrete will thus not have attained the prescribed improvements of the material properties due to lack of fibres, whereas other areas where the fibres lie too close, have become directly weakened, since the fibres in more or less coherent quantities form interfaces which are incapable of transferring tensile forces in the finished concrete construction.
  • the fibres are advantageously added during the dry mixing which treats the largest amount of materials, and during which the material still has a comparatively loose and easily workable structure.
  • the short time available during this mixing and which lies within the range about 1/4 - 1 1/2 min, it is important that the plastic fibres get into contact with as much of the concrete mixture as possible immediately during the dosing proper if a satisfactorily uniform distribution of the fibres in the mixture is to be achieved.
  • the fibres When first the fibres have been worked into the mixture they can as a result of their lightness and relatively large surface only with difficulty be displaced relatively to the far heavier content of stone and sand in the mixture.
  • the fibres are thus according to the invention added in an even and constant flow over a period which, as mentioned, advantageously may span most of the dry mixing period.
  • all parts of the concrete mixture will as a result of the mixing process little by little pass under the zone in which of the fibres fall down into the concrete mixer, and in this way at once become intimately distributed throughout the entire concrete mass.
  • this is e.g. achieved during the dry mixing period by advancing the fibre strings at a constant speed which precisely corresponds to the desired quantity of fibre cut per time unit.
  • the speed is sensed by means of the sensors 20 which give off signal to a programmed control unit (not shown).
  • This control unit may be equipped with a keyboard for coding in the data and desired material properties of the various mixtures, whereafter the control unit by means of its program automatically readjusts the number of revolutions of the cutter head 13, so that the cutter advances the fibre strings 12 at correct speed and cuts them into predetermined lengths which in the course of the dry mixing period sift down into the concrete mixture whereby they are evenly and uniformly distributed therein.
  • the cutter 9 can, as shown in figs. 1, 2, 3 and 5, be accomodated just above the concrete mixer 5, so that the fibre cut falls directly therein via the air duct 8. Because of conditions of space it may, however, sometimes be advantageous if the arrangement 6 is placed at some distance from the concrete mixer 5.
  • a belt conveyor 21 can be installed between the said mixer and the cutting arrangement 6, which conveyor conveys the fibre cut to the concrete mixer 5.
  • an air duct 22 may also be used for advancing the fibre cut, through which duct the fibre cut is blown by means of a blower 23.
  • the cutting arrangement 6 may e.g. be positioned in another storey also accomodating the supply of fibre string spools.
  • Fig. 8 is a top view of the complete apparatus provided with only one cutting arrangement 6.
  • the apparatus can advantageously also be equipped with exchangeable magazines 16 which are filled when they are not coupled to the cutter.
  • a magazine When a magazine is empty it can therefore quickly be replaced by a full magazine so that no time is wasted in operation when a magazine has run out of fibre string and must be supplied with fresh spools.
  • each concrete mixer may be provided with several cutting arrangements 6, as shown in fig. 10. When the arrangement used in a given moment, runs out of string, one of the other cutting arrangements, which in the meantime has been supplied with full spools, can immediately be put into operation.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Structural Engineering (AREA)
  • Preliminary Treatment Of Fibers (AREA)
  • Preparation Of Clay, And Manufacture Of Mixtures Containing Clay Or Cement (AREA)
  • Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
EP92610009A 1991-02-12 1992-02-11 Apparatus for cutting up fibre string into fibre cuts and dosing the latter into a concrete mixture Expired - Lifetime EP0499572B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DK023491A DK23491D0 (da) 1991-02-12 1991-02-12 Fremgangsmaade og anlaeg til ved opklipning af fibersnor i fiberklip at dosere dette til en betonblanding
DK234/91 1991-02-12

Publications (2)

Publication Number Publication Date
EP0499572A1 EP0499572A1 (en) 1992-08-19
EP0499572B1 true EP0499572B1 (en) 1997-10-08

Family

ID=8091246

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92610009A Expired - Lifetime EP0499572B1 (en) 1991-02-12 1992-02-11 Apparatus for cutting up fibre string into fibre cuts and dosing the latter into a concrete mixture

Country Status (4)

Country Link
EP (1) EP0499572B1 (da)
AT (1) ATE158977T1 (da)
DE (1) DE69222547T2 (da)
DK (1) DK23491D0 (da)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8322600B2 (en) 2007-10-02 2012-12-04 Nv Bekaert Sa Assembly for reinforcement for concrete and markers

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE501862C2 (sv) * 1993-10-05 1995-06-06 Confiber Ab Förfarande för tillsättning av armeringsfibrer i gjutmassa samt anordning för framställning och tillsättning av sådana fibrer i gjutmassa, exempelvis betongmassa
US6283327B1 (en) 2000-04-12 2001-09-04 Insulation Technology Corporation Material feed system for selectively delivering lightweight, friable mesh fibers
US6550362B1 (en) 2000-10-25 2003-04-22 Si Corporation Apparatus and method for dispensing fibers into cementitious materials
BE1014155A3 (nl) 2001-05-04 2003-05-06 Bekaert Sa Nv Werkwijze voor het doseren van wapeningsvezels bij de vervaardiging van vezelbeton en daarbij toegepaste kettingverpakking.
US6971784B1 (en) * 2002-09-06 2005-12-06 Bracegirdle Paul E Process for producing fiber reinforced hot-mix asphaltic and cementitous structural materials with fiber pellets produced from carpet waste
US7563017B1 (en) * 2002-09-06 2009-07-21 Bracegirdle Paul E Process for mixing congealable materials such as cement, asphalt, and glue with fibers from waste carpet
WO2005018896A1 (en) * 2003-08-15 2005-03-03 Bracegirdle P E Process for producing fiber reinforced asphaltic and cementitious materials
FR2866264B1 (fr) * 2004-02-13 2006-05-12 Jean Sebille Ensemble pour le gainage des fibres, l'extraction et le dosage des fibres dans le beton ou le mortier
AT524739A1 (de) * 2021-02-01 2022-08-15 Baumit Beteiligungen Gmbh Verfahren zur Herstellung von armierten 3D-gedruckten beton- bzw. mörtelbasierten Objekten
CN113414873B (zh) * 2021-06-28 2022-08-26 新兴栈(绵阳)建材有限公司 一种便于比例调和的混凝土制造设备
CN113733353A (zh) * 2021-09-17 2021-12-03 湖南岳煌建材科技有限公司 一种超耐久建筑用混凝土的生产工艺

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1489131A (fr) * 1966-06-06 1967-07-21 Verre Textile Soc Du Procédé et installation pour l'incorporation de fibres ou fils, naturels ou synthétiques, à des liants minéraux, notamment à des matériaux tels que le plâtre, qu'ils sont destinés à renforcer
JPS5328932B2 (da) * 1973-05-21 1978-08-17

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8322600B2 (en) 2007-10-02 2012-12-04 Nv Bekaert Sa Assembly for reinforcement for concrete and markers

Also Published As

Publication number Publication date
DE69222547D1 (de) 1997-11-13
EP0499572A1 (en) 1992-08-19
DE69222547T2 (de) 1998-04-23
ATE158977T1 (de) 1997-10-15
DK23491D0 (da) 1991-02-12

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