CA2160241C

CA2160241C - Reinforcing elements for castable compositions

Info

Publication number: CA2160241C
Application number: CA002160241A
Authority: CA
Inventors: James F. Sanders; Larry D. Rich; Clifford N. Macdonald; L. Max Hurlocker
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1993-05-03
Filing date: 1994-05-03
Publication date: 2003-07-15
Anticipated expiration: 2014-05-03
Also published as: AU685809B2; CN1126503A; US5807458A; KR100312333B1; CA2160241A1; JPH08511997A; ES2161766T3; CN1099945C; DE69428708T2; EP0725872A1; US5897928A; JP3510258B2; AU6780894A; EP0725872B1; DE69428708D1; WO1994025702A1

Abstract

Methods and articles for reinforcing castable compositions through the use of reinforcing elements (22) maintained in a close-packed alignment in a dispersible containment means (24).

Description

wo 94/2s702 ~ ~ 6 0 2 41 PCT/US94/048s6 REINFORCING ELE~ FOR CASTABLE COMPOSmONS
The present invention relates to the reinforcement of castable S col~lpoS;tionc.

BACKGROUND
It is well known that the pelrolllldnce of castable colllpositions can be improved by the incol~ldlion of ~einfor~ing elpmpntc~ For eAalllple, 10 reinforcing PkmPntc are incol~ldted into ~ n~itQus co...po~;t;o~c such as mortar and concrete to improve their strength or to reduce surface cn~^~ing tPn~en~ P~S~ Reinforcing ehPm~Pntc enajlllpdss a broad range of shapes, but theytypically share an elongate structure (i.e., the flim~Pncion of a major axis is cignifit~ntly larger than the limPn~ion of the minor aAis). The Plong"tP
15 structures include rod-like fil~mPntc having s~ sl~r.~;~lly round cross-sections, flat strips having a helically twisted structure or made with a varying cross-section to reduce pull-out ten~Pn~iP,s, or cable-like constructions bas_d on twisted constructions of rod-like filaments. M~tPri llc us_d as reinforcing elP-mentc include metals, synthetic polymeric materials, and naturally occu~. ;ng 20 mAtPri~lc.
In c~ nLilous colllposili'mc (i.e., mortar or concrete), it is known that the impact strength, fleAural strength and tol~ghnPcc of the material improves with increasing l~er~nldges of the reinforcing el~Pmentc in the col-lposiLion.
There is, however, a practical limit to the level of reinforcing elemPntc that can 25 be introduced as above this limit, the reinforcing el-pmpntc tend to ent~ngle with each other, forming balls or other undesirable conglomerates.
Proper ~PlP~tion of criteria relating to the length and ~i~meter (eg.
asp_ct ratio) of the reinforcing elPmPntC can help reduce their tendency to agglolllcldt~. Achieving improved mixability by this technique is difficult, 30 however, as these types of chAnges negatively impact the reinforcing capabilities of the el~Pm~Pntc W O 94/25702 ~CT~US94/04856 216~2'11 The method of delivering reinforcing elernPntc into ce~........................................................................ *,.l;lous cG~ )o~;l;onc also plays a major role in re~li7ing high inco~ ;on levels of reinforcing rlP.~ nl~ For example, high aspect ratio reinforcing clP ..cntc mustbe introduced into cel..i~nLi~ous co",?osiLions as substantially individual fibers 5 and in very low concentrations over an extended period of time with very good mixing if high volume concentrations of reinforcing elemPntc are desired.
Rod shaped r~ fo~ing elemPntc can become ent~ngl-Pd and/or aggloln~laL-ed in their shipping cont~;n~ ~ as a result of the vibration and jostling P.-.-o!.n~e,~d during shipping. Agglo,..~.dLed rle~..e~ ; are not readily 10 pourable from their shipping conti in_l~ and cannot be added to c~ nt;t ~uS
co",posilions until the agglo",c;,dtes have been broken up into individual el~PmPnt~. Various ",~ nir~l and pne,----~t;c techniques have been employed to break-up the agglomerated masses and introduce the individual elPmPnt~ into the cem~PntitQus mix a~s a rain of elPmentc U.S. Pat. No. 4,121,943 (Akazawa 15 et al.) describes a m^^~ine design-Pd to se~dle reinforcing fibers into S~IAIe units prior to introduçing them into the ce...---l;lous mix.
An ~lt~ e approach to incol~.dting high levels of re~nfol~;ing el~PmPnt~ into cemPntitous co",pos;l;on~ is described in U.S. Pat. No. 3,716,386(Ke~ er), where fibers are treated with a high viscosity, friction redu~ing 20 substance prior to the reinforcing el~PmPnt.C being introduced into the mix.
A factor common to a number of recent approaches to achieving high incol~,ulation levels of high aspect ratio elongate reinforcing ele~"c-,ni (i.e., fibers) into cemPntitous co...pos;l;on~ is to introduce the fibers into the co,l.posilion~ in an org~ni7~, aligned array that, on mixing, slowly releases the 25 fibers in an aligned array. Fibers released into PmPntitous co...pos;lions in this manner expe~ienc_ fewer fiber-fiber interactions and subsequendy show less ~end~Pncy toward agglomeration or balling as colllpa~cd to fibers introduced into the co",posilions in a totally random orientation. U.S. Pat. Nos. 4,224,377 and 4,314,853 (Moens) describe a reinforcing member comprising a plurality of 30 wire elem~ontc which are united by a binder which loses its binding ability during the mixing process, and a process for incol~ldting these l..f...h~ ~ into WO 94/25702 21~ 0 ~ 41 PCT/US94/04856 3 ~ t CP~ Qus co",pos;l;onc U.S. Pat, No. 4,414,030 (Rectrepo) describes reinforcing elem~ontc for c~n. -t;'~us co",l~il;onc comrricin~ ribbons of fibrillated polyolefin film. The fibrillat~d fibers are ,..qin~.in~d in an aligned configuration by inter-fiber fibrils which are broken by m~h-q-ni~-ql mixing, 5 thereby releqcin~ individual fibers into the c~me~ ouc co.,.posilion in an aligned configuration.
Another alternative to introduçing fibers into cementitQus co."posilions in an aligned configuration is described in Fiber Reinforced ~çmtontc and Concretes, edited by R.N. Swamy and B. Barr, Elsvier Applied Science, New 10 York, 1989. pp 316-325. This prl)cess~s utilizes short fibrillq~d polypropylene fiber strips which are twisted to pr~luce a cable-like structure to deliver the fibers to ce-,----.~;tQus co..~l~s;~;ons. The ...~hqnicql mixing action of proc~ccing the ce~ -t;lQUS co-"po~ilion breaks the cable-like structure apart, releqcing individual fihrillqted film fibers into the mix in an aligned manner.
SI~IMARY OF THE INVENTION
The present invention relates to a plurality of fiber bundles releasably held logell,~ in the form of a dis~l~ible un;t;~ package, each of the bundles comprising a plurality of high aspect ratio polymeric fibers ,..qintz..n~d in a 20 ~ubs~;~nl;qlly un~nt~-gl~ qrrqngement ~ub~ ;qlly free of inter-fiber binding,each of the bundles being adapt~d to release fibers from the bundles when the ~ e is introduced into a castable cG---posilion under dispersion con-lit;onc such that the individual fibers are released ~slal~t;qlly un~nPngl~ into the castable co.ll~;l;ol-.
The dispersion con-litionc col-te-.. rlated above and otherwise in the practice of this invention include the action of water or an organic solvent which is conlained in the castable cG...~si~ion, or heat ge~-f ~t~d by the castable co...~ n, or ",~h~ni~ql agit~tion of the castable co-nl)osilion, or any combination of two or more of the fo.~going, which action serves to 30 rele. se fibers from the bundles.

A p,~re"ed uniti7~ package of reinforcing elemp-nt-c for castable co~posilions comrricing a liquid/solid or liquid IlliA~U~s comrrioes a dispersible p~ ~ing means, the dispersion of which is ~rrecled by the cG---bined action of a dispersing agent present in the castable com~sition and S subst~nti~lly concu~ t ~-~h~n~ l mixing of the IlliAlu~e of the castable co...po~ilion and the uniti7~d package. The p~ eing means con~li~tec a multiplicity of primary packages of reinforcing elemPntc, the primary packages of reinforcing elemPntc comrricing a plurality of elong~te reinforcing PlP.mP.ntc which are ~ int~;n~l in a close-par~P~, side-by-side ~lignmpnt by a primary 10 dispersible col~t~in .~n~ means. The primary conhinm~p~nt means comrri~es a paimPtPr wrap Ill~inl~.n~ under sufficipnt tension to ~.~bsl;~nl;~lly restrict lateral movement of said elongate reinforcing el~prnpnt~c relative to one another.
Contii~uily of the primary cont~inment means is controllably disrupted by dispersion of at least a portion thereof, the dispersion of the primary 15 co~ inr..t~nt means err~cled by the combined action of a dispersing agent present in the castable cG",I)osition and sub~nl;~lly concurrent mPrh~ni~l mixing of the IlliAlule of the primary p, ^1~eS of l_;nfol~;ing C1e~ -nLC in thecastable co,~.pG~ilion. Disruption of the continuity of the primary cQnt~inmpnt means releases the elong~tç reinforcing elements and allows uniform mixing of 20 the elPmPntc into the castable cGIllpGsilion.
The present invention further provides a method for reinforcing a castable composition comprising the steps of introclu~-ing into a castable cG...~o~ilion under dispersion conditions a dispersible fiber bundle comprising a plurality of high aspect ratio polymeric fibers ~ inL~inP~ in a ~ul~s~ y 25 unf nl~nglP~l a~angement s~st~ lly free of inter-fiba binding, and thereafterrP1P~cing fibers from said bundle into the castable co...ros;l;on in a :iubs~.n~;~lly un~ ngled --annel.
A plerelled pl~SS for plep~ing a castable co---posilion comprising a liquid/solid or liquid ~iAlu~e, the IlliAlUl~; comprising a multiplicity of elongate 30 r~info~ing elemPntc comprises the steps of: a) ~l~paling a IlliAlule of ingredient m~tçri~lc for the castable co.. l o~;lion; b) Introducing at least one primary ~r~e of elongate re~foleing elpmpnt~ into the l~lixl~le, the package of reinforcing el~Pm~Pnt~ compri~ing a plurality of elong~t-P reinforcing el~PmPnt~
m~int~inPd in a close-p~c~P~, side-by-side ~lignmPnt by a primary dispersible con~; in",~nt means, the primary conl~;nlll~-nt means comprising a pçrimPtpr S wrap ,~inl~inpd under suffiri~Pnt tension to s~lbs~nl;~lly restrict lateral movement of said elongate rGinfol~ing elPmP.nt~ relative to one another. The continuity of the primary cont~inment means is capable of being controllably disrupted by dispersion of at least a portion thereof, the dispersion of the primary cont~inm~Pnt means being effected by the combined action of a 10 dispersing agent present in the castable colll~xssilion and the :~ul~s~n~ y concurrent ",~.l~nir~l mixing of the Illixlure of the at least one primary package of 1~ ;nfolcing ~le-"~ ; c) Mi-xing the InixlulG of the castable co",~ ;on and the at least one primary p~l~e of re;nfo~ing elPmP-nt~ to distribute ~ubs~ t;~lly uniforlllly the at least one primary package of l~for ing 15 elPmPntc into the castable m~tPri~l and to subsequently disrupt the continuity of the primary cQnt~inmPnt means, thus relP~ing the elong~te leinfc,l~ing elPmPnt~
into the castable c~lllpG~i~ion; and, d) Conl;n~ing to mix the IlliXlUlG of the castable cGIll~silion and the elong~tP rGinfo~ing ekpmpnts until the Plong~tP
reinforcing elPment~ are distributed subst~nti~lly uniformly throughout the 20 castable colllpos;lion.

BÆF DESCRIPIION OF THE DRAWINGS
Figure 1 is an illustration of a 1Ini~;7~:d package of reinforcing elements according to the present invention.
Figure 2 is an illustration of a package of elongate leinforcing PlPm~Pnt~
including a primary conl~inlllpn~ means, according to the present invention.
Figure 3 is an illustration of an ~lt~Prn~tive package of elongate le.nÇc". ing elP. ~ inrlutling a primary conL~inlllpnt means, according to the present invention.

2i6a24l Figure 4 is an illustration of an ~ltp-rn~tive pa~l~e of Plnng~t~P
reinforcing elemPnt~ incol~lating two dirrcrcnt sizes of reinforcing elPmPnt~
according to the present invention.
Figure 5 is a ~ llent of Figure 4 taken along 55 illustrating a method S of se~uring perimpt~pr wrap of primary COfil;.ifilllPIlt means 24.

DEFINl~ONS
As used herein:
"castable co"~sition" m_ans flowable co~ ;ons that can be cast as 10 such or can be applied to surfaces by alternative techniques such as ~I,otcrcle process used with ce---.enl;~ous co",po~ilions; such castable co,-,po~ilions include, for eY~mpl~, ce-..e~.l;l;ous co",~silions such as concrete or mortar;
b;l~...inous co...l~s;~;on~ such as ~sph~lt and polymer co",pos;~;on~, such as epoxy resms;
"liquidtsolid" means co"")osi~ions comprising a Illi~lulc of two or more liquid and solid co",poncnls; and "liquid ll~lure" means co~ ;on~ compr~ a curable liquid and optionally other liquid or dissolved cc"nponf~

INVENTION
Reinforcing elPmPnt.~ for castable colllpositionc~ and particularly for ce~ .t;lous co,nl)osilions, frequently have a much higher aspect ratio than the typical co",pone~,t~ of c~PmPntit~Us co",posiLions. This disparity in aspect ratio 25 makes unifol~ incol~l~ tion of reinforcing ekP-mPnt~ into cr...~n~;lous ~ ~s;l;on~, particularly at high volume percel~t~ges of reinforcing el~Pm~Pnt~, very difficult.
The present invention relates to a novel, Imiti7~d package of Plong~t reinforcing elPmpnt~ that allows the addition of high volume p~r~.,t~ges of 30 reinforcing fibers to castable co",posilions such as cemPntitous compositions in a single step while producing a subsl~ lly llniro"" incol~alion of the WO 94/25702 216 0 ~ 41 PCT/US94/048~6 - 7 - -;
individual ~;nfor~ing elemPntc throughout the ~-~..en~;lQ.Is co."po~ilion without "balling" or similar undesirable agglomeration formation. ~GÇeldbly, the lGinfolcing clP-,.enl!i are polyolefin, polyester, polyamide, polyimide, or polysulfone polymeric fibers. The present invention also relates to a process 5 for pl~ing r~folced castable c~.npos;~ ns using the Imiti7~ ~q~ e of elongPtP ~;nforcing elP...e-~c of the invention.
As illustrated in Figure 1, the 1lniti7~d package 10 of the present invention con~ t~Ps a mllltiplicity of primary p~ agPs of rGinfo.cing elemPntc 20 in a dispersible conl~ihlll~pnt means 12 that can be added to castable 10 co",posi~ions in its entirety. The dispersible contqinment me. ns comprises co...pocil;onc whose COhtinUil~ can be disrupted, at least in part, so as to release the con~-nlc of the package, by the combined action of a dispersing agent (such as water, an organic solvent and/or heat) present in or generated by the co.,.posilion and concurrent mP~hqni- ql mixing action. Co.-~l)osilions suitable15 for use in aqueous cc~ P~nl;~ous co~pos;~;onc include, but are not limited toc~P-lll-lose based papers, ce~ lose based papers sdtul~t~d or coated with water swellable or water dispersible binders, etc. Suitable water swellable or water dispersible binders that can be used in conjunction with the water dispersible con~in~Pnt me ns include, but are not limited to polys~h~rides, gelatin, and 20 poly(meth)acrylic acid. The water swellable or water dispersible binders can be applied to the water dispersible cont~.n...en~ means by any of several techniques commonly used to apply binders to paper-like web constructions, including, but not limited to roll coating, squeeze roll saturation, knife coating, and gravurecoating proc~-cces. The dispersibility, or time required to disrupt the con~inui~y 25 of at least a portion of the uniti7~ p~ age suffi~iently to cause its con~nts to be rele-q~, can be controlled by the basis weight of the water dispersible p~^~a~ing means, the type of binder and the binder incol~lation level.
The primary packages of reinforcing cle .. nl~ 20 of Figure 2 which are cont~in~d within the uniti7~d package 12 comprise a plurality of elongate 30 l~inrol.;ing c4..-,-.L~i 22 ~ ;nl;.;n~ in a close-packed, side-by-side qlignm~nt by a pe im~t~, wrap of a primary col-~;hl..e.-~ means 24 compricin~ co...~,~ nc '216~2 4 1 - 8 -whose cont;.-~ y can be disrupted, at least in part, so as to release the cQnt~Pnt~
of the package, by the combined action of a dispersing agent (e.g., water, an organic solvent and/or heat) present in or gen~ldted by the cr~ nt;l~us co,l,po~ilion and subst~nti~lly concurrent ~..e~ nic~l mixing action.
5 Co",po~ilions suitable for use in aqueous cel e~ t;tQUS CG .p(S~;t;on~ inr.lllde, but are not limited to cellulose based papers, cellulose based papers sdluldted withwater swellable or water dispersible binders, and water dispersible PSA tape constructions. Suitable water swellable or water dispersible binders that can beused in conjunction with the water dispersible co~ ;n-.-Pnt means include, but 10 are not limited to poly~c~ rid~ps~ gelatin, and poly(meth)acrylic acid. The water swellable or water dispersible binders can be applied to the water dispersible conl~ir....- nt means by any of several techniques commonly used to apply binders to paper-like webs constructions, inr,lurling, but not limited to roll coating, squeeæ roll saturation, knife coating, and gravure coating pr~c~-~.~s.
15 The dispersibility, or time l~uired to disrupt the continuity of the primary COfit~;filllf':l-t means s~fficiently to cause the release the reinforcing elemPnt~, can be controlled by the basis weight of the water dispersible p~cL~ging means, the type of binder and the binder inco,~ldlion level.
Cylindrical primary packages of fibrous reinforcing elemPnt~ 20 can be 20 readily fabricated from a fiber tow or a hank by w~pping the tow or hank witha strip of primary cont~inm~Pnt means m~teri~l in a spiral overlap ",anner to form a core of l~infol~;ing elemP-nt~ 22 with a pe~;".~l~r wrap of a water dispersible con~ifi...Pnt means and cutting the tow or hank to produce reinforcing cle ..- nl~ of the desired length. The dispersion of the primary 25 p~^~es of reinforcing ekPmPnt~ 20 can be e~tP-n~ed by utili7ing a higher basis weight primary cofit-~;n...e.ll means, by utili7ing a primary cor.l;.il-...Pnt means having a higher binder add-on, or simply by incl~iilg the a,--ount of overlap or the nUIII~l of ov~llapping layers of the primary cQnl~.n.. ~nl means 24.
An ~ltçrn~tive primary package of reinforcing elemPnt~ 30 is shown in 30 Figure 3, wherein four sep~ale primary packages of reinforcing ~k "Pn~ 20 have been incol~ldted into a single p~cl~e by an additional pe~imP,t~P~ wrap WO 94125702 216 0 2 4 ~ PCT/US94/04856 g , .. . .
34. Pe~ te~ wrap 34 may comprise a sepa,dte wrap or, al~l"dti~ely, it may comprise an eYt-encion of the pçrimPt~Pr wrap 24 of one of the ~q-~es of l~infolcing el~PmPntc 20. Primary reinforcing element packages 20 may all contain the same reinforcing elPmentc or each package may contain different S size l..nforcing elen~
A third alternative primary p~ ~e of reinforcing elPmpntc 40 is shown in Figure 4, wherein a central core package of reinforcing elçmp~ntc 42 confine~by perimet~Pr wrap 44 is surrounded by a concentric assembly of a second reinforcing PlemPnt 46 having a dirÇ~lenl ~iqmet~Pr or cross-section. ~ltPrnqtive 10 pacl~-q~ging options illustrated in Figures 3 and 4 allow the introduction of a customized blend of reinforcing elPmPntC into a castable cG",posilion by the useof a single primary package of reinforcing elPmPntc Referring to Figure 4, primary conL~inlll~ t means 24 may exhibit sufficiPnt cohesive attraction to itself to keep terminal end 48 of the top 15 o~,lapping strip from unwinding after the fiber tow or hank has been cut to produce primary packages of reinforcing PlPmPntC. In the event that there is inc~lffici~Pnt coheshe attraction between adjacent layers, an optional dispersible adhesive 28 may be applied across the width of outer face 26 of primary conl;~;n...Pnt means 24 as, for e-~...ple, a strip of a dispersible hot melt 20 adhesive or strip of a dispersible transfa adhesive, as primary cont~in...~ nl means 24 is being wrapped around r~inf~,~ing elPmPntc 46. Dispersible adhesive 28 should be sel~P~t~P~ so that it is dispersible by the same dispersing agent used to disperse primary col.~;~in...-Pnt means 24 or another dispersing agent which is co,l~patible with the castable co.--position to which the primary25 package(s) of leinfor~ing elemPntc is being added.
As shown in Figure 5, which is a fragment of Figure 4 along 55, fibrous re;nfGn,ing elP-mentc 46 are con~ ~ by primary con~ n...ent means 24. Terminql end 48 of the top o~.lap~ing layer of primary con~;~il-...~nt means 24 is secured to the adjacent layer of primary co~ in~çl~t means 24 by 30 an optional strip of dispersible adhesive 28 which forms a strip coe-lenC;~Je with the longitu~in-ql a~is of reinforcing ele-..entc 46 (more cle rly seen by referring 2160241 lO-to Figure 4). Dispersible adhesive 28 is preferably applied to the outer face 26of primary CO~ f nt means 24 so that it does not contact reinforcing cl-...f -lQ 46.
It is also conte",plated that a dispersible shrink wrap m~tPri~l might be S utilized for the perimeter wrap for the primary con~i~;n~ .~-nt means. In addition to providing the shrink wrap capability, suitable m~tPri ~lc would also have to exhibit ~s~n~;~lly similar dispersibility pclço"~ance to the m~tPri~lc describedabove.
Regardless of the shape or design of the primary package of ~cinforcing 10 ekPmPntc~ the p ;..,eler wrap around each package is ",~int~;nPd under suffi~ient tension to subst~nti~lly restrict the lateral movement of the elongate reinfol~ing elefnPntc relative to one another. This restriction of lateral movement of lGinrorcing ele-mpntc relative to one another is prere,lcd to prevent pr~,,,alulc release of the reinforcing elemf~ntC~ either during shipping or 15 during r~ lditiQn to castable co",~s;l;~nc. In addition to providing a convenient and or~ni7Pd ",anner of intro~ucing the reinfo~ing elpmpntc into castable co.ll~;liQnc by errecLing a ci~nifir~nt reducti~n in the volume of ~einfo~eing elf mfntc introduced into cG",pO ,ilions at a critical mixing point, the p~r~ingalso provides a distinct shipping advantage in that it ~rin~; ;nC the reinforcing 20 elpmpntc in a configuration that will not permit agglomeration during shipping.
~d~litionAlly, the primary pr^1~e is ~ignifirr~ntly more dense than a co---~-i-t le volume of unco~ tP~ elemPntc, thereby allowing a signifie~ntly greater weight of rle "enL~ to be sllipped in the same volume occupied by the uncon~lid~t~l ele.m~Pntc~
Cylin-lrir~l packages of reinforcing cle."~nt~i can range in height from about 0.25 cm to about 20 cm, preferably from about 1.0 cm to 10 cm, and from about 0.25 cm to about 20 cm, plefeldbly from about 1.0 cm to 10 cm in ~iAmet~r. Even though this size range can result in packages having a cignifirr~tlt fli~rity in size and shape relative to other co",ponenl~ of typical 30 Ce-~ ;tOIlS co",po~ilions, the packages of reinforcing elemPnts are readily mixed into the ce ,lenl;l,uus co~pos;l;onc in a ~ub~l~r,~;~lly unirol....-,anner.

WO 94125702 21~ ~ 2 41 PCT/US94/04856 Upon disruption of the continuity of the perimeter wrap and the resl-lting tension it has ~ ;n~;npd on the reinforcing elem~Pnt~, the e~emPntc are rapidly dispersed into the C~ ou~ m~lure with minim~l, if any agglomeration.
While not being bound by any theory, it is presumed that this lack of S agglomeration is due, in part, to the fact that the ~ forcing elpmpnt~ are in~;n~ in a or~ni7~, su~s~ lly parallel arrangement on release. On being relP~, the el~mPnt~ c~rlinue to act in an aligned fashion, further enh~n~ing subst~nti~lly uniform macro-distribution of the el-omPnt~ throughout the c~...ent;lQus co...~s;l;Qn until the individual ehPmP-nt~ are wetted and 10 dispersed.
It has been observed that even though the pc~ e~r wraps are ~ubs~ lly i-lenti~l on each primary package of reinforcing elf-~nL~ they exhibit a range of dispersing times. This range in dispersion times allows the addition of a high conc~..n~tion of rc,nfolcing cl/~ nl~, in the form of the 15 primary E~cl~e of reinforcing clP~ s, to c~ -n~;lous cG...~os;l;on~ as a single charge. Reinforcing Pl~..."nl~ are ~u~sc~luently released from the primary p^^~gP~S in a controlled manner such that there is minim~l, if any, agglomeration and the reinforcing ele-..----L~ are distributed throughout the cemPnl;lous cc...~s;l;rln~ in a s.bsl;~ lly unifol... manner.
This pr~pos~d incol~l~lion ".~nicm stands in contl~l to the introdl~ction of individual cl~ into c~..f nlilou~ ~;I;onC in a totally random oriPnt~tion that would allow inter-fiber interactions and .,ub~uent agglomeration of the ekmpnt~
In a broader aspect, each of the bundles or primary packages is 25 configured, for cAa---ple, as a bag or tube which contain the fibas in a s.-bs~; nl;~lly ImPnt~nglPd arrangement. Other configurations for the plilllal~
package are suitable provided they provide for release of fibers in the desired ...~ner when eA~sed to dispersion con-lition~, ~efe.dbly the primary packages of leinfo~ing cle ..~ are free from 30 binders that bind individual ~nforcing elPment~ together (ie. inter ele-..f.-t binders). The ^',sel-c~ of int_r cle-.~n~ binders f^^ilit~t~ps a more Iapid 216~24~

dispersion of the elPm~Pntc as the binder does not have to dissolve to allow release of the individual el~PmPntc~
The present invention also conte",l,lates a process for the incolpol~tion of elongate reinforcing P.lP~mpntc into castable compositions, the process 5 compricing the steps of: a) ~rep~ing a ~ix~ur~ of ingredient mqtPriqlc for thecastable c~mposiLion; b) Intro~ucing at le. st one primary package of ek~ngqt-P
reinforcing PlPmPntc into the mixture, the primary package of r~foreing ekPmP-ntc compricing a plurality of elongq-t-P reinforcing elpmentc mqintqinP~ in a close-p.~ P~I, side-by-side qli&nmPnt by a primary di~ ible c~fitA;m..~
10 means, the primary dispersible c4ntAin~ nt means compricing a perim~Pter wrap~.qint~inP~d under s--ffi~iPnt tension to restrict lateral movement of said elongate reinforcing rle~ relative to one another. The conlinuily of the primary dispersible co,.~ nt means is capable of being controllably disrupted by dispersion of at least a portion thereof, the dispel~ion of the primary dispersible 15 con~ ....c.-t means being erÇ~d by the combined action of a disp~,~ing agent present in the castable co...l os;l;on and ~.~stAnl;qlly concu~ t ".~hAni-mixing of the l,~lule of the at least one primary package of lelnro~ing elemPntc; c) Mixing the llli~lule of the castable co",posilion and the at least one primary package of reinforcing elemPntc to distribute subslA.-L;-q-lly 20 unirollnly the at least one primary package of reinforcing elemPnLc into the cq~t^l le mqtPriql and to subse~lu~.,tly disrupt the c~ y of the pli~
dispersible contvinment means, thus ~1~AC;ng the elongqtP .~inror~ing elemPntc into the castable composition; and, d) Continuing to mix the ,,,i~lu.c; of the castable c~mpo,ilion and the PlongqtP reinfo~ing elP-mPntc until the elnngqtç
25 reinforcing clP n~n~c are distributed s.lbs~-nt;Ally uniformly throughout the castable co",po~ilion.
The process cont~"~plates the introduction of one or more ~miti7~d packages of le;nfolcing elp .l n~c into a castable c~",posilion, depPnding on the level of reinforcing elPmPntC .~uiç~ for the colll~silion. A ll~lule of si_es 30 of ~info~ing elP--..~ntc can be introduced into the co"~po~ition by a) incol~.ating primary pack. ges of dirr. l~nt sized e~ in each lllliti7f~

21602~1 package, or b) by utili7ing Imiti7P~ packages cQn~inil-g only one size of reinforcing elemPnt~, but adding lmiti7~d p~ ~es cor.n-ining different sized ek ..~nl~ in the appr~plialc ratio to achieve the desired final co---posiliom In another embodim~Pnt, the process also conLe.--plates the addition of - S primary p~ ~Ps of le;nfo~ing cle ~enlc as individual bundles or packages rather than using the un;l;7P~ p;~cl~e previously described. Custom~zed reinfor ing elemPnt blends could readily be prcp~ed using individual primary p~ ~PS simply by weighing or counting out the appropliate mlmher of plilll~ packages of differing size or structure and adding the ll~lul~ to the 10 castable co",posilion. Mixing times might be shortened using this embo~imPnt as additional time to disrupt the continuity of the llniti7~ package would not be r~uilcd.
The dispersing agent may be present in the mix of co"-ponents of the castable c~"~osilion (water in the case of a c~Prn~pntitQus co",posiLion) prior to 15 the addition of the u~ ~l package of reinforcing elementc~ or, alternatively,the dispersing agent may be added to the castable co...l os;l;on subse~uent to the ~d~iti~n of the un;l;~ p, ^l~e of reinforcing el~PmPnt~ Addition of the di~ ing agent subsequent to the ~ition of the l-niti7Pd package can afford a longer time for the ..n;1;7~ p,~l~ag~Ps to be subst~nti~lly uni~ollllly incol~oldtcd 20 into the castable co...~ n before inil;~ g the disruption of the dispersible ~tlr~ing means and the perimtoter wrap material. In either case, mPch~ni~l mixing action supplied by the mixing of the Illi~lu~ of the uniti7~d package andthe castable co"lpo~ilion ~ubs~ lly concurrent with the presence of the dispersing agent is ~UilUI to achieve dispersion of both the p~ing means 25 and the primary cQn~;n~ -n~ means m~tP~ri~l~
It is desirable to control the dispersion time of the pPrimPter wrap so that the disruption of its corltinuily does not occur prior to the disruption of the conlinuity of the p~clr~ing means. Premature release of the Icinfolcing el~ n.enL~ while they are still cQnt~inP~ within the Un;t;7f~d package could result 30 in undesirable agglomeration of the reinforcing elementc.

WO 94/25702 PCT/US94/048~6 216024~ 14-In a broader aspect, each of the bundles or primary pq~ qgPs used in the process of the invention is configured, for eYqmple, as a bag or tube which contain the fibers in a ~ l"t~nl;qlly ~ ;.nglP~d arrangel"~nt.
~ efeldbly, each bundle or primary package contains greater than about 5 50 fibers or reh~fo~ing e1-omPnt~ and most preferably cont-in~ bclween about 100 and about 10,000 fibers or lGinfo~ing elem~Pntc It should be understood that the present invention con~- ..plates the use of the llniti7f~l package of reinforcing elPmPnt~ and the process of inco.~ldLing the l~lnfor~ing ~1P.~ nL~ into other castable cG...poc;l;on~, inclll~ing, but not 10 limited to reinforced polymeric colll~s;lionc (either thermoplastic or thermoset cG...~;~;ons) and ceramics. When non-aqueous based CO...pOS;~ are utilized, al~l"ati~e ~ ging and pçrimeter wrap mqtPriql~ whose conli-,uities can be disrupted by dispersing agents c4lllpdLible with the cadstable c4"lpo~iLion would be s~sLi~uLed for the water dispersible p~l~ing and pe- ;...ete wrap 15 mqteriql~. A replesc--~ e nonaqueous construction inc4l~uld~s a polystyrene pPrimPt~Pr wrap for use in a styrene based co",~s;L;~m When b;lu---i~-ous or other hot ~ for~d co---pos;l;~n~ are utili7f~, heat g~ ldted by the castable col"posiLion may be used as the dispersing agent. It should also be understood that pqr~ ng and pf.;.nPtçr wrap materials which are sensitive to dispersing 20 agents other than water can be utilized in aqueous based castable col"~siLions as long as the dispersing agent is coll,pdtible with the castable c4lllposiLion.
E~AMPLES
Reinforcin.~ Fiber I
Drawn polypropylene fibers (4:1 draw ratio) having a diqmpter of 0.81 mm (0.032 inches) was cut into 5.1 cm (2.0 inch) lengths and stored in a plastic bag for later use. The density of the loose fibers was ap~ç~ t~ly 50 gm/liter (0.5 lb/gallon) Reinforcin~ Fiber II
Drawn polypropylene fibers (4:1 draw ratio) having a ~i~mPpr of 0.13 -0.2 mm (0.005 - 0.08 inches, available from ~tPm~ Co., Specialty Fil~mPnt~

~o 94/25702 2 16 0 2 4 ~ PCT/USg4/04856 - 15- ~ `
Division, Od~onton, MD) was cut into S.l cm (2.0 inch) lengths and stored in a plastic bag for later use.
Reinfol~;n~ Flçment p~qrk~e I
Appr~ ,lately 180 cm (71 inches) long samples of Reinforcing Fiber I
- were formed into hanks of approximqtely S. l cm (2.0 inches) in ~ qmpt~r and wrapped with S. l cm (2.0 inch) wide 3M Brand Repulpable Tape #9023 (an a1kali dispersible tape available from 3M, St. Paul, MN) in a spiral wrap with S an apl)n~Ai",~ ly 0.6 cm (0.25 inch) overlap on each wrap. The wrapped hank was then cut into S. l cm (2.0 inch) lengths using a guillotine cutter to obtain bundles of le~nfo~ing fibers. The density of the fiber bundle was approximqt~ly 20 gm/liter (2.4 lb/gallon).
Reinfol-;in~ Flement p~q.~k~e II
Reinfo~ing F.l~mPnt Package II was formed according to the procedure used for Reinforcing Fl~m~nt Package I except that Reinforcing Fiber II was used as the fiber.
Example 1 A mortar mix comprising Portland cement (22 kg, 48 pounds), s. nd lS (123 kg, 270 pounds) and water (17 kg, 38 pounds) was added to a 0.17m3 (6 ft3) capacity concrete mixer and mixed until a homogeneous Illi~lule was o~ ined. Reinfol~ g F1~mPnt Package I (3.5 kg, 7.7 pounds, 7 volume percent) were added to the ~ lule as a single charge. The packages were observed to unifol~ly mix into the mortar mix and then break open, rele-qcing 20 the l~infolcillg fibers over a period of approximately 7 .llinules. Mixing was continued for an additional 20 minutes, or a total mixing time of about 30 JIPS. Minimql free fibers were observed in the mix and there was no evidence of fiber ball formation.
Coln~ti~,re Example C-l The procedure of Example 1 was lepealed except that the reinforcing fiber was added as loose fibers. Loose Reinforcing Fiber I (3.5 kg, 7.7 pounds, 7 volume percent) was added to the mortar Illi~lule in ap~roAimately 0.25 kg inc~,nenls and the Illi~lule allowed to mix for app~ tPly 4 Illinut~s 21~241 before the next in.;~ ,ent was added. The tot. l mixing time was about 60 ..;,-ut,s. If the loose fibers were added in any larga incrG.~I~nls they irreversibly agglomerated into fiber balls.

S F~aln~)le 2 Reinforcing Fiber I, (61 kg, 135 pounds, 3 volume pel~cnt) was added to a 2.3 m3 (3 yd3) high strength conel~t~ mix comprising sand (2,333 kg, 5138 pounds), coarse aggregatG (1,702 kg, 3750 pounds), Portland cement (810 kg, 1782 pounds), water (359 kg, 789 pounds), fly ash (205 kg, 450 pounds), water 10 reducer (6 liters, 204 ounces) and an air entl~in...~-nt additive ( 0.41 liters, 14 ounces) in a Ready Mix truck in a slow continuouc manner over a 30 minute period. The res~lting co..~l~s;l;on was mixed for an ^ ~ tion~l 10 Illillu~, after which applu.ulllately 1.5 m3 (2 yd3) of the mix was removed. Some irreversible agglomeration of fibers into balls was observed even though the 15 fibers were carefully added over a period of approximately 30 minutes. An qA~litinnql 7 kg (15 pounds) of Reinforcing Fl~mcnt Package I, which CO11~ PC1 to an ^~l~itionql 1 volume percent, were added to the rc~ qining 0.76 m3 (1 yd3) as a single charge and mixing continued an vq ~itionql 20 minutPs No ^~ itiQnql fiber balling was observed ~se~uent to the addition of 20 the p~c~ages of ~ Çûr~ g elemPnt.~, even though the concrete mix was in an unstable con~iti~n which would promote ball formation.
FY~q~mple 3 The pr~lule of Example 1 was l~xat~d except that Reinforcing F.l~.mPnt Package II (1.1 kg, 2.4 pounds, 2 volume percent) was added to the 25 mix as a single charge. The packages were unifollllly mixed into the colllpo~ilion and began to break open and release the fibers after a period of approximqtely 3 ,..inutes A visual c~ t;on of the mix after mixing an ,~l~litiQnql 7 Illinu~s (10 ...inu~s tot. l mixing time) showed no evidence of unûp~ned packages of reinforcing cle ..enl~. Samples were taken from the mix 30 after a total mixing time of approximqtPly 20 I"inu~s, the ~ s cast and cured and s~u~ntly e~-q-minP~ for fiber distribution in the mix. F~.llin~;on WO 94/25702 ~ 16 0 2 1 ~ PCT/US94/04856 of the cast samples showed uniform fiber distribution and no evidence of fiber ball formation.
Co",p~dLi~e Example C-2 The pr~lule of Example 3 was repeated except that the reinforcing 5 fiber was added as loose fibers. Loose, une-nt~ngled Reinforcing Fiber II (.51kg, 1.1 pound, 1 volume percent) was added to the mortar mixture in approximately 0.26 kg increments (0.5 pounds) and the mixture allowed to mix for approximately 10 minutes before the next increment was added. The total mixing time was about 20 ",inules. Attempts to add more loose fiber to reach a 10 1.5 vol. % fiber resulted in fiber ball formation. Even though a smaller amount of fiber was added to the mix over a longer period of time, the res~-lting mix showed evidence of undesirable fiber agglomeration as co-"p~d to Example 3.
Example 4 A Pug Mill was ch~ed with 7000 pounds (3180 kg) of a "driveway mixH con~i~ting of a 50/50 mix of course and fine aggregate and a 5.5% by weight of asphalt m~int~ined at about 370F (188C). A garbage bag conli.h-il-g approAimately 7 pounds (3.2 kg) of polyethylene wrapped nylon fibers as described in Reinforcing Element Package III above was added 20 through an inspection port and allowed to mix for approximately one minute, during which both the uniti7ing package and the primary conti-;n,-,~ont package melted to release the reinforcing fibers into the asphalt. The asphalt was tested using an asphalt paver, and it was found that the fibers were mixed uniformly throughout the asphalt. Minimal free fibers were observed in the mix and there 25 was no evidence of fiber ball formation.
Co",~dti~e Example C-3 The procedure of Example 4 was repeated except that seven pounds (3.2 kg) of loose Nylon fibers as described in Reinfo,cing Fiber III above were added in a 30 gallon (132 liter) polyethylene garbage bag. The asphalt was 30 again tested using an asphalt paver, and it was found that many of the fibershad not mixed in, and instead were found to be in the form of entangled balls Wo 94/25702 PcT/usg4/048s6 ~16024~

having a ~i~metPr of about 2-3 inches (5.1-7.6 cm). The balls did not contain asphalt in their centers and caused blistering of the pavement.

Claims

WHAT IS CLAIMED IS:

1. A unitized package of reinforcing elements for castable compositions comprising a liquid/solid or liquid mixtures, said unitized package comprising a dispersible packaging means, the dispersion of said packaging means effected by the combined action of a dispersing agent present in said castable composition and substantially concurrent mechanical mixing of the mixture of said castable composition and said unitized package, said packaging means enclosing or consolidating a multiplicity of primary packages of polymeric reinforcing elements, said primary packages of reinforcing elements comprising a plurality of elongate reinforcing elements maintained in a close-packed, side-by-side alignment by a primary dispersible containment means, said primary containment means comprising a perimeter wrap maintained under sufficient tension to substantially restrict lateral movement of said elongate reinforcing elements relative to one another, the continuity of said primary containment means capable of being controllably disrupted by dispersion of at least a portion thereof, said dispersion of said primary containment means effected by from the combined action of a dispersing agent present in said castable composition and substantially concurrent mechanical mixing of the mixture of said packages of reinforcing elements in said castable composition to release said elongate reinforcing elements and allow substantially uniform mixing of same into said castable composition.

2. A unitized package of reinforcing elements according to Claim 1 wherein said castable composition comprises a cementitous material such as mortar or concrete.

3. The unitized package of reinforcing elements according to Claim 1, wherein said elongate reinforcing elements are free of inter-element binders.

4. A process for preparing a mixture of a castable composition comprising a liquid/solid or liquid mixture, said mixture comprising a multiplicity of elongate reinforcing elements, said process comprising the steps of:
a) preparing a mixture of ingredient materials for said castable composition;
b) introducing into said mixture at least one unitized package of elongate reinforcing elements, said unitized package comprising a dispersible packaging means, the dispersion of said dispersible packaging means effected by the combined action of a dispersing agent present in said castable composition and substantially concurrent mechanical mixing of the mixture of said castable composition and said unitized package, said packaging means consolidating a multiplicity of primary packages of reinforcing elements, said primary packages of reinforcing elements comprising a plurality of elongate reinforcing elements maintained in a close-packed, side-by-side alignment by a primary dispersible containment means, said primary containment means comprising a perimeter wrap maintained under sufficient tension to substantially restrict lateral movement of said elongate reinforcing elements relative to one another, the continuity of said primary containment means capable of being controllably disrupted by dispersion of at least a portion thereof, said dispersion of said primary containment means effected by the combined action of a dispersing agent present in said castable composition and substantially concurrent mechanical mixing of the mixture of said primary packages of reinforcing elements in said castable composition;

c) mixing said mixture of said castable composition and said at least one unitized package of elongate reinforcing elements to disrupt the continuity of said at least one unitized package of reinforcing elements to distribute substantially uniformly said primary packages of elongate reinforcing materials into said castable composition and to subsequently disrupt the continuity of said primary containment means, thus releasing said reinforcing elements into said castable composition; and d) continuing to mix said mixture until said reinforcing elements are distributed substantially uniformly throughout said mixture.

5. The process according to Claim 4, wherein said at least one unitized package of elongate reinforcing elements is introduced into said castable composition and the mixing continued a sufficient time to distribute substantially uniformly said at least one package of elongate reinforcing elements in said mix prior to the disruption of said primary containment means.

6. The process according to Claim 4, wherein said dispersing agent is present in said castable composition prior to the introduction of said at least one unitized package of elongate reinforcing elements and the mixing continued a sufficient time to distribute substantially uniformly said at least one package of elongate reinforcing elements in said mix prior to the disruption of said primary containment means.

7. The process according to Claim 4, wherein said dispersing agent is introduced into said castable composition subsequent to the introduction of said at least one unitized package of elongate reinforcing elements and the mixing continued a sufficient time to distribute substantially uniformly said at least one package of elongate reinforcing elements in said mix prior to the disruption of said primary containment means.

8. The process according to Claim 4, wherein said elongate reinforcing elements are free of any inter-element binders.

9. A plurality of fiber bundles releasably held together in the form of a dispersible unitized package, each of the said bundles comprising a plurality of high aspect ratio polymeric fibers maintained in a substantially unentangled arrangement substantially free of inter-fiber binding, each of said bundles being adapted to release fibers from said bundles when said package is introduced into a castable composition under dispersion conditions such that said fibers are released substantially unentangled into said castable composition.

10, The unitized package of Claim 9, wherein said fibers comprise polyolefin fibers.

11 The unitized package of Claim 10, wherein said castable composition comprises a cementitious composition.