CA2191002A1 - Cellulose-gum fiber composites and their use in preparing building construction products - Google Patents

Abstract

In the preparation of building construction products containing cementing agents including portland cement, aluminium or magnesium cements, lime, limestone, silica, gypsum, or clay, cellulose fibers are sometimes added in order to obtain products with reduced density and higher heat insulation value. The use of cellulose fibers for this purpose often leads to many processing disadvantages and sometimes inferior products.

In the present invention are given methods and formulae for attaching water soluble polycarbohydrate hydrocolloids or gums to cellulose, allowing the preparation of gum-fiber composites or gumfers. Hydrocolloids are precipitated onto cellulose fibers by means of employing a mineral salt together with an acidulant, under specific conditions of pH and temperature.
The gum-fiber composites or gumfers formed have more desirable properties than untreated forms of cellulose and are chemically reactive with cementing agents. Gumfers may be added to building product formulations at high levels of concentration, resulting in products which have improved properties compared to those made using prior art methods.

Description

Background of The Invention:

The present invention relates to methods and formulae for attaching poly-carbohydrate hydrocolloids to cellulose fibers in order to prepare what are known as gum-fiber composites or gumfers, and the use of such composites in preparing building products.

Gumfers are reactive with inorganic cementing agents including Portlandcement, magnesium or aluminium cements, lime, silicates, gypsum plaster, and clay, which are used to prepare building products including for example:
cement or plaster based castings; tiles; roofing shingles; non-fired bricks and building blocks; wall sheathing; sub-flooring; mortars; filling and patching compounds; and dry cementing mixes. Said gum-fiber composites may be used as filling or as reinforcing agents for cementing agents, the incorporation of which results in improved working properties of wet acqueous admixtures and in improved physical properties of the building products formed thereof, including for example: low density, high strength to weight ratio, and increased volumetric yields.

The methods involve the attachment of hydrocolloids to cellulose and tohemi-cellulose fibers in high weight ratio by inducing hydrogen bonding at pH values less than 7.0, and by co-precipitating with mineral salts, including for example: salts of calcium, magnesium, aluminium, iron, and salts of oxides, carbonates, silicates, sulphates, phosphates, or borates.

By polycarbohydrate hydrocolloid is meant all water soluble or water dispersible forms of complex carbohydrates including those starchy or gummy substances found in plants, algae, fungae, or bacteria, which are sugar polymers and are chiefly carbohydrate in nature. Said carbohydrates are generally composed of repeating units of simple sugars such as for example, glucose, galactose, mannose, arabinose, rhamnose, or gulose, together with randomly or regularly repeating units of uronic acid sugar units such as for example, glucuronic, galacturonic, mannuronic, or guluronic acids, and also with randomly or regularly repeating units of sulphated or phosphorylated sugar units including for example, glucose-6-phosphate, or galactose-2,4, or 6-sulphate. Examples of such gums include: sodium alginates, agar, carrageenin, gellan gum, xanthan gum, starch phosphates, and pectins.

By cellulose is meant alpha-cellulose, micro-crystalline cellulose, or hemi-cellulose, or all such water insoluble polycarbohydrates, chiefly composed of repeating glucose or xylose units in linear beta 1,4 linkage, which are found in plant cell walls.

According to prior art methods, the addition of fibers to cementing agents as fillers or reinforcing agents in making building products is well known and includes not only the use of cellulose fibers but also of glass, metal, mineral, and synthetic polymer fibers as well. To give only one example of prior art use of cellulose fibers in a building product formulation, the technique of adding straw to mud or clay in order to prepare sun-dried bricks was practised by early civilizations. Normally, only a small pro-portion of fibers may be incorporated into a wet acqueous mixture contain-ing cementing agents without causing deleterious effects on either the wet mixture thus formed or on the final building product itself, and in the case of cellulose fibers, the maximum amount of cellulous material which may be added seldom exceeds 10% by weight of the cementing agent employed, or a ratio of 1 parts fiber to 10 parts cementing agent. In the case of cements, lime, gypsum plasters, and clays, water is an essential component to be added to all such materials, not only to achieve workability, but also to react with inorganic cementing agents in order to form a solid, crystalline structure of good strength bearing properties, in which the added fiber is imbedded after hardening and curing.

Physical and chemical properties of the fiber and its reactivity towards the cementing agent are important as concerns the reinforcing effect of fiber on tensile or compressive strength of the building product, and the effect of its inclusion on other properties such as th~rm~l expansion, and density. For example, particle size, fiber length, surface area, density, water absorption capacity, thermal coefficient of expansion, elasticity or brittleness, tensile strength, and chemical or physical reactivity of the fiber compared to the cementing agent, all bear measurable effect on final properties of the building product formed. To give several examples of effects af properties of the fiber on building products; if surface area of fiber is large for exa~ple, then an excess of liquid water may be required to wet the fiber as well as to saturate the cementing agent and other additives, thereby contributing to weeping of water from acqueous mixtures or to a reduction in final bond strength in the building product after curing; if fiber density is comparable to that of other ingredients, lightness or high strength to weight ratios in the product may not be achieved; if physical or chemical attraction for cementing agent is poor, then low adhesion to cohesion ratios may result so that the fiber is insufficiently bonded to the agent, and physical separation from the product results on impact or stress; if thermal coefficient of expansion of fiber differs greatly from that of the cementing agent and other additives after curing, then the fiber may separate from the product when subjected to extremes of either temperature or moisture or both, especially so and also if bonding of fiber to the product is poor.

When preparing products using inorganic cementing agents, the compoundsusually being in the form of dry, free-flowing powders, or in the form of a wet cake in the case of clay, are first wetted with water in order to form a slurry or paste, and various fillers including, sand, stone, gravel, pazzolanic materials, ignaceous materials such as perlite, micaceous materials such as vermiculite, and other additives including accelerating or retarding agents, curing and bon~ing agents, and colorants are added in various proportions. Where a fiber is to be used, it is usually added in a manner similar to that employed for other fillers. Wet mixtures are then paured or cast into forms or molds, or may be used as mortars, grouting compounds, or as slips in order to coat surfaces, or to repair cracks and fill crevices. Often, and before castings begin to set, the surfaces of such mixtures are spread over or worked in with a trowel, in order to pack the mixture firmly into the mold or crevice and to obtain a smooth surface finish once the product has been hardened and cured; therefore, wet mixtures must be of suitable consistency to permit workability, and the desired consistency is usually obtained by varying the proportion of water or other additives added to the mixture. Next, the mixtures must be allowed to remain undisturbed while chemical reaction with added water takes place and before the mixtures have begun to set and harden in order not to weaken final bond strength which it is desired to create. Castings are at this point usually covered over to prevent rapid evaporation of moisture from surfaces which could lead to shrinkage cracking, or improper curing.
Finally, after sufficient hardening, casting frames are carefully removed, and the product is allowed to dry thoroughly by natural or forced convection, which completes the curing stage, allowing the product to develop its ultimate bond strength.

According to prior art methods, when fibers containing a high cellulosecontent are added to building products, there generally results the need to use an excess of water beyond that normally required in order to form a manageable slurry or paste. Cellulose fibers generally have a high water absorption capacity compared to other cementing agents or additives, there-fore an amount of water in excess of that normally required must be added to the mixtures. Cellulose fibers also possess a feathery nature, consequently fibers tend to nest or interlock, making spreading, casting, and surface finishing difficult. In attempts to eliminate nesting, additional quantities of water are again often added in order to promote lubrication. Cellulose fibers are also chemically inert, so that any bond-ing which does take place is purely physical.

These factors, coupled together with the need to use excess water, lead to many disadvantages to the use of cellulose fibers in building products.
For example, wet mixtures tend to separate on st~n~;nq due to attraction of cellulose fibers for one another. Gross separation of components, shrinkage and cracking, weeping of water from mixtures, and spalling of cn~ron~nts from casting surfaces often occurs. Wet mixtures have longer hold-out periods before setting, and require longer periods of time to dry.
The final bond strength in the cured articles is often weakened, both due to the excess of moisture which has been added and also due to the inertness of 21qlO02 cellulose.

Particularly when cellulose fibers in the form of coarse wood chips, sawdust, or splinters is used, these materials often contain substantial quantities of water soluble substances or of insoluble oils or resins such as lignin. Such impurities may effect final bond strength similarly to the use of excess water, since the soluble impurities interfere with setting, and the oils and resins are water repellant.

In order to improve the degree of chemical and physical bonding betweencellulose and cementing agent, thereby improving ultimate bond strength, building products are often formed using a pressure technique in order to express both trapped air and water and to compact the wet mixtures. The pressed material may then also be heated or accelerating agents may also be added in order to accelerate the rate of setting and curing in the products.
These methods, although resulting in an impL~v~-l~nt in bonding, also result in greater density so that little or no advantage of the low density of cellulose fibers and the ability of such fibers to create air poc]~ets in the products once excess moisture has been expressed or removed by evaporation during curing and drying, is to be obtained. For example, pure cellulose possesses a pycnometer density of 1.4 g/cc whereas cementing agents and other additives possess densities between 2.3 and 3.0 g/cc. Expanded cellulose fibers containing air can achieve bulk densities as low as 0.1 to 0.2 g/cc, and hence possess superior heat insulating value compared to other building materials. When mixtures are compressed, the potential insulating quality of cellulose is lost. The use of such methods also necessitates an unusual expenditure of energy and equipment beyond that normally required.

Since both the moisture expansion coefficient and also the thermal coefficient of expansion of cellulose fibers often differs significantly from that of other c~ r~ s in a building mixture, and also since binding of fibers within the matrix of the building product is often poor for reasons previously given, the products often have a tendency to shrink and crack while drying, and also when subjected to extremes in either moisture or temperature, and the products are, therefore, in many cases unsuitable for exterior construction purposes in particular.

It can be seen from the preceding that prior art processes in which cellulose fibers are employed are seldom successful in achieving significant advantages in working properties, strength or impact resistance, lightnessl or durability, which permits wider use of the products in a variety of applications, particularly as concerns exterior uses. Building products containing cellulose fibers are, therefore, limited to interior uses such as for example:
patching compounds or wall panelling, the latter of which is often prepared using pressure techniques and consequently offer no impLo~t,.~nt in either strength or density over existing products made without the use of cellulose fibers. Attempts at purification of fibers by alkaline bleaching to remove impurities, or by grinding to finer particle size, do not seem to alter the properties of cellulose to any significant extent to be of greater benefit when used in building product formulations.

In view of the failure of prior art technology to provide either methods or forms of cellulose suitable for use in building products to be of beneficial advantage, it is an object of this invention to provide methods for reacting such fibers with hydrocolloids or gums in order to prepare gum-fiber composites or gumfers. Said gumfers exhibit increased chemical and physical reactivity with cementing agents, resulting in improved properties of building formulations and the products obtained thereof. Said composites are convenient to use when added to building formulations, and do not result in products which exhibit many of the preceding disadvantages of prior art methods.

Gumfers prepared according to the methods of this invention possess superior physical and chemical properties compared to untreated forms of cellulose, including for example: elasticity, lubricity and ability to chemically react with cementing agents and physically bind with aggregate fillers to a controlled and variable degree according to their manner of preparation.
When used in building product formulations, gumfers may be used at concentrations exceeding 10% by weight of the cementing agents employed and up to 25~/o by weight of the cementing agents employed, or a ratio of 2.5 parts gumfer to 1.0 parts cementing agent. Gumfers hold moisture in acqueous mixtures and prevent weeping, permit good workability, do not interfere with setting or hardening, result in products which dry and cure rapidly, do not exhibit shrinkage or cracking or spalling of components from surfaces after curing, have a smooth surface finish, possess low density, greater durability, and increased strength and impact resistance compared to prior art products made using conventional cellulose fibers.

The methods and products of this invention do not require special equipment or energy intensive methods in order to improve binding between fiber and cementing agent. Consequently, the products of this invention may be made to exhibit superior heat insulating qualities, strength, and lightness in weight compared to existing products.

Since the products of this invention do not possess a susceptibility to decay and disintegration as do other products made using conv~n~ional forms of cellulose, they may find use in a wide variety of applications both exterior as well as interior including for example: cement or clay roofing shingles, or exterior or interior siding or sheathing, especially when such products are also waterproofed after being formed and cured using c~-'v~ntional prior art waterproofing techniques.

The methods of this invention are not limited to the use of only purified forms of cellulose, but may be demonstrated on a wide variety of cellulose substrates including for example: bleached or non-bleached paper pulp, sawdust, wood chips, recycled newsprint and boxboard, or by-products from agriculture or food processing. Th2 methods of this invention can in many instances overcome the deleterious effects of water soluble impurities and oils or resins present in these materials.

Since the preservation of forests is rapidly bec~m;ng a growing envi.ol~.~ntal issue, the use of by-product cellulose fiber sources .such as recycled newsprint, agricultural wastes, or forestry slash, to prepare building products which are composites containing a high percentage of cellulose fibers which can replace existing wood products, will be a trend of the future. The methods of this invention will allow for the preparation of building products containing high percentages of cellulose which can replace existing wood products, thereby having the potential to reduce environmental impact caused by deforestation.

The methods of this invention result in dry, powdered, free-flowing forms of gum-fiber composites which are suitable for use in building formulations in order to prepare dry pre-mixed compounds such as mortar mixes, patching or grouting ~"L~o~lds, or mixes suitable for casting applications. Alternatively, the methods of this invention allow for the preparation of moist gumfers which are not dried before use and may therefore be used directly at site of the building product application, by adding various cementing agents and fillers to the moist gumfer, and using the mixtures thus formed to produce the final building product.
Summary of The Invention:

m e inventive idea which this invention embodies is to suspend a material containing a relatively high proportion of cellulose fibers in an acqueous hydrocolloid solution at a temperature of between 5~ and 25~C, to which is then added a mineral salt and an acidulant.

m e acidulant reacts with the mineral salt and also with the hydrocolloid, releasing cations of the mineral salt into the medium. m e cations of the mineral salt and the anions of the acidulant interchange for those cations and anions which are associated with uronic acid groups of the hydrocolloid, thereby causing the hydrocolloid to precipitate or to gel. The acidulant is added in sufficient quantity to both neutralize the hydrocolloid and the mineral salt as well as any other alkaline substances which may be present or added, and also to reduce pH in the suspension to a value less than 7.0 but greater than 2Ø me reduction in pH promotes not only an exchange of cations with the hydrocolloid, but also attachment of the hydrocolloid to cellulose by means of hydrogen bonding. The cations and anions provided by the mineral salt and the acidulant, the hydrocolloid, and the cellulose fibers are subsequently all together precipitated out of solution.

The cation-anion reacted hydrocolloid coats the cellulose fibers, forming a gum-fiber composite or gumfer which is insoluble in water. The solution which remains as a supernatent fluid is non-gelatinous and non-adhesive, has a water-like consistency and may therefore be easily separated from the gumfer, the hydrocolloid having been removed from solution by co-precipitation.

The gum-fiber composite may be rinsed or washed with water to remove residual salts and acid, and then also drained or filtered, and pressed to a moisture content of 50~/0 or less. The gumfer may then be dried to a moisture content of10% or less and reduced to any desired particle size by grinding, using conventional methods. The gumfer is then suitable for use in building product formulations containing inorganic cementing agents. Alternatively, after most of the water has been removed by draining or filtration and the gumfer has beenwashed, the gumfern~ed not be pressed or dried, but is instead left in a moist state in the form of an acqueous suspension or cake, to which may then be added cementing agents and other additives in order to obtain a wet formulation suitable for the preparation of building products. It is found that when gumfers are added to building product formulations, the cation and anion reacted sugar residues of the gumfer are reactive with cementing agents used in such formulations. Water used in the process, after having been recovered from the gumfer by straining or pressing, may be recycled to the beginning of the process in order to prepare new quantities of gum-fiber composites.

The cellulose fiber source used to prepare gumfers, may be dervied from any suitable plant source and used in any suitable particle size which permits agitation of the hydrocolloid suspension, including for example: wood chips, sawdust, splinters, or bark from woods, plant stalks or straws, forestry slash, tree stumps, seed hulls, fruit fiber, sugar cane bagasse, sugar beet pulp, soya fiber, and other wastes from forestry, agriculture, or food processing operations; bleached or non-bleached paper pulp; newsprint or box-board; purified forms of alpha-cellulose, microcrystalline cellulose, or hemi-cellulose; grass clippings, leaves; or seaweeds and other algae. Since the cellulose source may also contain substantial quantities of impurities such as oils or lignin, therefore, the cellulose source should also contain at least -50~/O by weight as cellulose or hemi-cellulose to be of practical use for the purpose of this invention.

As it is preferable to suspend the cellulose source in a gum solution using as high a concentration as is physically possible in order to permit agitation and reduce water consumed in the process, the cellulose source is~preferrably-first reduced in particle size using co~lv~-tional methods, in order to permit the use of higher concentrations and lesser energy requirements for agitation.

As to the types of hydrocolloid which may be used, it is found that not all hydrocolloids are suitable for purposes of this invention, although many hydrocolloids are known which will associate with cellulose through hydrogen bonding. In general, only those gums with a mostly linear backbone and a m;n;mllm degree of side-branching, which possess structural characteristics similar to cellulose, are useful for purposes of this invention. Such gums mUst also possess a relatively high proportion of acid groups including for example: carboxyl, sulphate, or phosphyl, attached to the linear backbone of the gum chiefly by means of carbon atoms 2,3, or 6 of repeating sugar units.
Other specific structural characteristics also appear to be necessary as for example, the types and repetitive nature of sugar units in the backbone, and the manner in which these units are linked together, as for example via beta 1,4; beta 1,6; or beta 3,6 linkages. In general it is found that the more closely the gum resembles cellulose in structure and in composition, the lesser the degree of steric hindrance imposed by side chains or acid groups, and the greater degree of the reactivity of the gum particularly with multi-valent mineral cations such as Ca, Mg, Fe, Al, then the greater will be the affinity of the gum for cellulose through hydrogen hon~;ng and co-precipitation, and the greater the degree of bond;ng between gum and cellulose, resulting in a more permanent and durable, and not readily dissociated form of gum-fiber composite, which is ~ st suitable for purposes of this invention.

Gums which are most suitable for purposes of this invention which may be used alone or together in combination include the following:
Alginates, derivedfrom seaweedsFomposed of linear segments of D-mannuronic acid and L-guluronic acid, and alternating residues of these acids in beta 1,4 linkage, preferably when used in a sodium salt form, ; carrageenin, also derived from seaweeds, composed of nearly linear repeating galactose and 3,6-anhydrogalactose units, both sulphated and non-sulphated at carbon positions 2,4 or 6, and preferably when used in kappa or iota forms, these forms being more sensitive to monovalent ions K, MH4, and also to multivalent mineral ions, including Ca, Mg, ; agar, also from seaweeds, a similarly linear and sulphated polygalactose ester, ; gum ghatti, a mixed polymer of L-arabinose, D-galactose, D-mannose, D-xylose, and D-glucuronic acid, with linear backbone mostly of galactose, mannose and galacturonic residues, with acid labile side chains, preferably when used in a most linear form with side chains removed by acid treatment, ; pectins from fruits, which are linear polymers of galacturonic acid, both methylated and non-methylated, the pectic acid monovalent ion salt form, or the de-methylated form being most preferred, ; dextran, composed of linear chains of 1,6-isomaltose linked glucose, preferably when used in sulphated form as dextran sulphate, ; gellan gum, of bacterial origin from pseud~on~ elodea, composed of linear chains of glucose, glucuronic acid, and rhamnose, acylated with acetate and glycerate, preferably when used in a low acyl or de-acylated form, ; xanthan gum, from the bacterium xanth~n~ campestris, composed of linear chain backbone of repeating glucose units linked beta 1,4 similarly to cellulose, and trisaccharide side chains comprised of a glucuronic acid residue be~ two mannose residues, the furthest from the chain carrying a pyruvate group, the one closest being acetylated, and especially being used whenever mineral salts cont~;ning ferric or iron (III) cations are used in the process, ; carboxy-methyl cellulose, a cellulose polymer with carboxy-methyl group substitution on carbon positions 2,3 or 6 of repeating glucose units linked beta 1,4, preferably when used in a low degree of substitution form, and especially when mineral salts containing tri-valent ions including ferric or aluminium ions are used in the process, ; starch phosphate monoesters or oxidized starch, preferably linear amylose fractions with repeating sugar units phosphorylated or carboxylated at carbon positions 2,3 or 6, and preferably when used in a pre-gelatinized form, ; konjac flour, welan gum, guar gum, rhamsan gum, locust bean gum, and cereal beta glucans, especially when used in a form which is either phosphorylated, sulphated, or carboxylated at carbon positions 2,3 or 6, of sugar residues.

Gums which are less preferred or are unsuitable for purposes of this invention for the following reasons include:
; gums which are mostly linear, hence do associate with cellulose through hydrogen bonding, but which do not possess uronic acid groups, hence do not gel or precipitate with mineral salts, including, guar gum, locust bean gum, dextran, konjac flour or mannan, welan, rhamsan, cereal ~-glucans, dextrins or amylose in their natural or unmodified forms. Guar gum and locust bean may be induced to gel with borate ions at a pH greater than 7.0, therefore, the use of these gums is limited to a specific variation of the invention, ; Gums which do exhibit a limited degree of association with cellulose through hydrogen ~on~;n~ and also possess free acid groups, but also possess side chains or are highly branched and, therefore, do not gel or precipitate with mineral salts, including: gum arabic, gum ghatti in natural form, tragacanth, karaya, amylopectin, polydextrose, and xanthan. Xanthan gum will gel only in the presence of ferric ion at the pH of this invention, hence is only useful when iron (III) salts are used as precipitants.
; Gums which are mostly linear, but contain a high proportion of uronic acid groups affording steric hindrance, hence exhibit limited association with cellulose and limited gelling capacity with mineral salts, including:
carboxymethyl cellulose, or lambda carrageenin, ; Gums which are mostly linear but contain side chains offering steric hindrance and no uronic acid groups, including: methyl, hydroxy-methyl, hydroxy-ethyl, and hydroxy-propyl cellulose, or mixed esters of these.

Other gums and hydrocolloids which do associate with cellulose to a limited degree and do exhibit gelling or precipitation with mineral salts~ but are proteinaceous in nature, and are hence less preferred because of their greater susceptibility to bacterial and fungal decay compared to hydrocolloids, including: casein, albumin, gelatine, and gluten.

It is found that preferred gums such as those precedingly described may also be used in combination, and that certain combinations where the gums are synergistic with one another and one of the gums is less preferred, or is a non-preferred gum may also be used. For éxample, a mixture of carrageenin which is preferred and konjac flour which is not preferred, or, a mixture of alginates which are preferred and pregelatinized amylose starch which is not preferred, may be used to prepare gumfers.

The mineral salt may be a soluble or insoluble salt in hydrous or anhydrous form, cont~;n;ng any of the following mineral element cations, used alone or together in combination: Li; K; NH4; Ca, Mg, Be, Sr, or Ba: Ti, or Zr; V, Cr, or Mo; Mn; Fe; Co; Ni, Pd, or Pt; Cu, Ag, or Au; Zn; Pb; Cd; Hg; Al, *r Ga; Si, Ge, or Sn; Ce; or Bi, and for purposes of this invention is most preferably a salt of relatively low solubility in water cont~;n;ng the cations Ca, Mg, Ba, ~e, Al, Zn, NH4 , or K.

The anionic group of the mineral salt may consist of any of the following, used alone or together in combination; oxide; hydroxide; chloride; bicarbonate or carbonate; phosphate; orthophosphate; pyrophosphate; hydrcapatite;
phosphonate; phosphite, metaborate,tetraborate; flourite; aluminate;
aluminosilicate; fluosilicate; magnesium silicate; silicate; silicide;
metasilicate; orthosilicate; sulphate; sulphite; bisulphate, thiosulphate;
sulphide; selenate; tungstate; pyrate; arsenate; nitrates;or,an organic acid anion consisting of: acetate; lactate; citrate; gluconate; tartrate; malate;
fumarate; maleate; stearate; adipate; succinate; benzoate; phthalate, but for purposes of this invention is most preferably an oxide, carbonate, sulphate,phosphate including meta, ortho, and pyro forms, fluorite, fluosilicate, and other silicates including meta or ortho forms, or mixed metal forms of silicates. The mineral salt may also consist of a natural or synthetic 21~1002 .

mineral substance including for example: Portland cement, clay, talc, lim~stone, silicate, gypsum, pulverized concrete or brick, hydroapatite, hydroboracite, hydrohaematite, hydromagnesite, or hydrophite, all of which are governed by the preceding. For example, Portland cement is a mixture of calcium silicates, calcium hydroxide, and calcium sulphate.

The acidulant may be a salt which produces an acidic reaction when dissolved in water, or an acid itself, either highly soluble or of low solubility in water including: acidic salts of Na, K, NH4, Ca, or Mg, for example, monophosphates:
soluble mineral acids including: hydrochloric; sulphuric; nitric; phosphoric, phosphorous, phosphonic, phosphinic, and organo derivates of these: boric;
sulphonic; or organic acids including: acetic, lactic, citric, gluconic, malic, malonic, tartaric, carbon dioxide, or carbonic acid; or organic acids and anhydrides of low solubility in water, including: maleic, fumaric, adipic, succinic, stearic, benzoic, phthalic, aspartic, or glutamic; or organic substances which revert to an acid form when dissolved in water including:
glucono-delta-lactone, or carbon dioxide. For purposes of this invention, acidic substances which are most preferred include: monophosphates, hydrochloric acid, sulphuric acid, phosphoric acid, and organo-derivates of phosphoric, phosphorous, phosphonic, or phosphinic acids, boric acid, sulphonic acids, organic anhydrides or acids,and carbonic acid or carbon dioxide.

Now, as concerns optimum conditions and variables of the process, including for example, water hardness, pH, temperature, ingredient concentration, and as to the choice of mineral salt, acidulant, hydrocolloid, or cellulose source used, and the effect of these choices on methods of preparation and on properties of gum-fiber composites and their use in building products, reasons for preferred choices are given as follows.

According to methods of this invention, it is found that when a hydrocolloid of preferred characteristics as previously described is dissolved in water, a gum-like solution of viscous and adhesive nature is formed. When cellulose fibers or materials of relatively high cellulose content are added to the solution, the cellulose fibers being insoluble, are observed to swell due to absorption of water from the solution, but remain suspended. No reaction between cellulose and the hydrocolloid is evident since the solutîon within the suspension remains viscous and adhesive and no reduction in viscosity is apparent. If, however, either a highly soluble mineral salt or a salt of low solubility containing the cations K, NH4, Ca, Mg, Al, or Fe for example, is added, then depending on the type of gum used, the solution containing the hydrocolloid will gel, and if the pH is also lowered to a value between 2.0 and 7.0 the suspension will im~ediately thin and the gum precipitate out into the cellulose fibers, leaving behind a clear supernatent fluid of water-like consistency, free of precipitate, which fluid and the precipitate itself are non-gummy and non-adhesive in nature. It is also found, that if an acid-ulent alone is used without added mineral salt, that a certain degree of flocculation or precipitation also takes place, which is not as prominent as when a mineral salt is also added, and that afterwards the solution still remains somewhat gum-like or adhesive in nature.

From these observations it may be deduced that the hydrocolloid attaches itself to cellulose fibers by means of hydrogen bonding, and is associated with cellulose in a hypothetical helix structure held in place by the mineral cations and anions contained by the mineral salt and acidulant which have been added and are now part of the gum-fiber composite itself. This deduction is confirmed by either heating the gumfer suspension or the moist precipitate, or by raising the pH to a value greater than pH 7.0, in which case it is observed that the suspension or the precipitate become gel-like and adhesive in nature once again, indicating that hydrogen bonding between gum and fiber has been disrupted and that the gum has been released back into solution once again. This disruption in hydrogen hon~ing is not observed when the gumfer has been dried to a moisture content of 10% or less, and only occurs when the gumfer is remoistened and adjusted to an alkaline pH value greater than 7.0, or is reheated to a temperature above 30 C. The hypothetical hon~;n~ between cellulose and hydrocolloid together with mineral cations and anions is similar to that which occurs in plants, between the cellulose of cell walls and the gum matrix into which the cells are imbedded. For example, in plants, calcium and silica are often found in significant amounts and are believed to act as cementing agents, holding hydrocolloid and cellulose in place.

If the mineral salt is highly soluble,then immediate gelling of hydrocolloid without addition of acidulant occurs, so that it may be difficult to add acidulants to the mixture in order to induce hydrogen bonding and co-precipitation of the gumfer, due to swelling of the mixture, the mixture now being unstirrable. Therefore, it is most preferable to use a mineral salt of low acqueous solubility such as previously described, including for example: oxides, carbonates, di- and tri-phosphates, silicates, or sulphates, of Ca, M~, Fe, or Al, so that cations of these salts are more slowly released, controlling the rate of gelling and precipitation of the hydrocolloid. The gelling rate may also be similarly controlled when the acidulant also possesses a low solubility or a low rate of conversion to an acid form. The mineral salts and acidic substances may be added in the form of liquid solutions, or dry, granular, or crystalline materials, but are most preferably first pre-dispersed, pre-dissolved, or pre-diluted in water before being added to ensure their complete dispersion or dissolution in the suspension and to prevent pocket reaction from taking place. Hence, it may be seen that the choice of mineral salt and acidulant can be widely varied in order to control both rates of gelling and precipitation to ~esiredadvantage.

It is also found that the preferred temperature of the suspension is less than 30~C and is preferably between 5~ and 25~C, in order to prevent gumfers from dissociating. The final pH in the suspension may be between 2.0 and 7.0, but is preferably between pH 3.0 and 5.0, which is effective for purposes of gelling and co-precipitation and in order to conserve the amount of acidulant to be added, or to limit the amounts of soluble impurities which may have to be later removed from the precipitate by washing or pressing.
If the final pH is less than 3.0, then excess acidity may strip metal cations from the hydLocolloid~ in which case the gumfer will be obtained in a free acid form, which form may not be entirely suitable for purposes of this invention.

As concerns the nature of cations and anions used, it is found that certain hydrocolloids may be ;nduce~ to gel using mineral salts cont~ining sodium, potassium or am~onium cations, for example, gellan gum or carrageenin. As will be seen from the disclosure which follows~that except for ammonium or potassium in certain cases, these particular cations are not entirely desirable for inclusion in a building product formulation.

For example, where the gumfer is to be used in a formulation containingportland cement powder which is a mixture of calcium silicates, it is most preferable to use a calcium salt such as calcium silicate or cement powder itself as the mineral salt used to precipitate the gumfer. Also, since phosphates, phosphonates, sulphates, sulphonates, borates, and carbonates have a proven and beneficial effect on bonding and curing properties of portland cements, it is preferable to use either phosphoric, phosphonic, sulphuric, sulphonic, boric, or carbonic acids, or suitable combinations of these acids as acidulants, since anions and cations of these salts and acids when attached to the gumfer, together with residual amounts of ions left over unreacted in the solution, will then be incorporated into the build-ing product when the gumfer is added, thereby providing a beneficial effect.

Similarly, where gumfers are designed to be used in a building product formulation which contains gypsum, plaster of Paris, or partially or fully hydrated calcium sulphate, then it is most desirable to employ either calcium sulphate, calcium carbonate, calcium oxide, calcium hydroxide or calcium silicates or cement powder, or combinations of these for example as the mineral salt, and also potassium salts as well, and to add sulphuric acid as the acidulant, which results in the formation of calcium and potassium cations and sulphate anions in the suspension, which will then be incorporated into the gumfer. The gumfer will then display greater reactivity with gypsum or plast~rbased formulations. For example, potassium salts are known accelerators for setting of Plaster of Paris formulations. Similarly, when using gumfers to prepare lime based mortars or mortar mixes, it is preferable to precipitate gumfers using calcium oxide or calcium hydroxide as the mineral salt, and to add carbonic acid or carbon dioxide as the acidulant. Finally, when preparing clay based products as for example non-fired ceramic castings, clay tiles or bricks, it may be desirable to use clay, talc, or other aluminium, iron or magnesium silicates as the mineral salt, and to use carbon dioxide, hydro-chloric acid, or acetic acid as the acidulant. Obviously, a wide range of formulations is possible.

The choice of mineral salt and acidulant is also pre-determined by the types of cations and anions which are residual in the supernatent solution after reaction,some of which will be residual in the gumfer, especially so if the gumfer is not washed after precipitation. For example, most hydrocolloids are available for use in a dry, powdered, sodium salt form, where Na cations are attached to anionic carboxyl, phosphyl, or sulphate groups of the hydrocolloid. When an acidulant is added, the acid formed reacts with the mineral salt to release cations of the salt which are P~ nged for sodium cations attached to the hydrocolloid. After reaction, sodium ions donated by the gum, and anions of the acidulant remain in solution. For example, if calcium lactate is added as the mineral salt, and hydrochloric acid is added as the acidulant, then after reaction, sodium, chloride, and lactate ions all reside within the solution so that in essence the solution contains both sodium chloride and sodium lactate. If these salts are not adequately removed by washing and pressing techniques after precipitation, then when the gumfer is used in a portland cement based formulation for example, such salts may interfere with setting of the cement and may effloresce to the surface of the product after curing. In this example, it would be more desirable and especially when the gumfer is not washed or pressed after precipitation, to employ either phosphates, carbonates, silicates,or borates as the mineral salt, and phosphoric acid, carbonic acid, or boric acid as the acidulant, since residual salts cont~;n;ng sodium ions which are formed in these cases willconsist of either sodium phosphate, sodium carbonate, sodium silicate, or sodium borate, any of which may have a more beneficial effect on setting and curing properties of cement based formulations when included together with the added gumfer, washing of the gumfer to remove trace impurities after preparation prior to its use in a building product formulation thus being less critical.

Thus, it can be seen that the mineral salt and acidulant may be selected from a wide variety of sources, the choice of which is not only based on the ability of such substances to react with hydrocolloid and induce precipitation, but is also based on a sound knowledge of cementing agent chemistry, whether the gumferis to be used in cement, plaster, lime, or clay based formulations, The chemistry of such cementing agents is well-known to anyone trained in the science of using such materials.

When preparing gumfers using a mineral salt, it is desirable to include lesser quantities of salts of ammonium, Ba, Cd, Cu, Ag, Zn, Pb, or Hg, and also silicates, phosphates, borates, or sulphonates, for the following reasons.
Ammonium salts and borates when residual in gumfers and thus in the building product forumation itself, particularly when phosphate anions are also present, will confer properties of fire-retardancy on gumfers and also on the building product, and the use of mono-, di-, tri- or poly ammonium phosphates for this purpose is already well-known. Copper, cadmium, silver, zinc, lead, or mercury salts for example, are toxic to microorganisms, and their use will help prolong life of gumfers and also the building product, when exposed to moist, humid conditions, as for example in exterior use. As previously described, phosphates, silicates, and borates improve ultimate bond strength.
Zinc, barium, and silicates confer properties of water repellancy on concrete products, and silicates also accelerate setting and curing. It may be advantageous to include water soluble silicates such as sodium or potassium silicates together with insoluble salts of Ca, Mg, Fe, Al, in order to produce mixed silicates such as aluminium ferrosilicate, calcium magnesium silicate or calcium aluminosilicate when preparing gumfers for example since certain combinations of these may be beneficial for cement or clay formulations.

The prece~;ng gumfer chemistry may be illustrated by means of the following reaction s~m~:

Example Gum Na Salt + Mineral + Acidulant = Gelled Gum + Salts Salt Residual in Supernatent 1 Gum-C02Na + MgC12 +HCl = Gum-C02(MgCl) + -NaCl, HCl 2 Gum-C02Na + Ca(HP04) + H3P04 = Gum-C02Ca(H2PO4) + Na2HPO4' Na(H2P04), H3P04.

3 Gum-C02Na + CaSiO3H20 + H2S 4 = Gum-co2casio4H3 + Na2so4~ H2 4' Gum-C02Ca(HS04) Na2SiO3,H2SiO3, sio2 .

4 Gum-C~2Na + CuS04 3 2 = Gum-C02Cu(Acetate) +Na Acetate, (acetic acid) Cu(Acetate)2, Na2S04, Acetic acid.

Gum-C02Na + CaC03 + H02CRC02H = Gum-C02Ca- + C02, Ca(HC03), (maleic acid) -02CRC02Ca(HC03) Na Maleate.

6 Gum-C02Na + ZnO+ C02 = Gum-C02Zn(HC03) + Zn(HC03), Na2C03, N2(HC03) H2C03 .

Hydrogen bonding of gelled gum to cellulose occurs by means of hydroxyl groups of both gum and cellulose, on carbon positions 2,3,or 6 of sugar residues, and is reinforced by Hydrogen ions in solution, or at pH values less than 7Ø

As relates to concentrations and ratios of ingredients to be employed, the hydrocolloid is usually employed at a concentration of between 1% and 2~o of an acqueous solution. Since most hydrocolloids yield solutions which are highly viscous at low concentration, it is desirable to use the lowest viscosity forms of these gums wherever possible to permit higher gum loadings and greater batch yields, so that in some cases 5% to 8% gum solutions are possible, for example where low viscosity grades of alginates are available for use.

The cellulous material may be used at any concentration between 5~/0 and 20%
by weight of the hydrocolloid solution, which permits convenient agitation.
Hence, the ratio of hydrocolloid to cellulose fiber may be infinitely varied between O : 1 and 1 : 1. For practical purposes of this invention however, gum : fiber ratios are varied between 1 parts gum to 20 parts cellulose and 1 parts gum to 2 parts cellulose. By means of such variation in gum : cellulose ratio, the amounts of gum added to cellulose fiber hence the degree of reactivity towards cementing agents may be controlled and varied up to and including some practical maximum, which is determined by the types of mineral salt, acidulant, hydrocolloid, and cellulose source used to prepare gumfers.

The mineral salt may be used in any concentration however, for practical purposes, the mineral salt is used in an amount nearly stoichiomentric with that required to react all uronic acid groups of the hydLocolloid, plus uronic acid groups of the cellulose source due to uronic acid hemicellulose content. For example, in the case where an alginate is used, the typical equivalent weight of a repeating sugar unit in alginic acid is given as between 176 and 194 daltons. Since each sugar residue in an alginate molecule contains at least one uronic acid group on average, the amount of mineral salt to be added ~o react with alginate is to be det~rm;ne~ as follows:

Weiqht of sodium alginate in formula x Combining weiqht of mineral salt used Combining weight of sugar residue cont~;n;ng one free acid group in Na salt form = Weight mineral salt to be added.

Generally, the mineral salt is used at a c~-~ntration of be~ n 25% and lOO~o by weight of the hydrocolloid added.

The acidulant is added in an amount stoichiometric with that necessary to displace all cations attached to uronic acid sugar units of the hydrocolloid, and therefore in an amount stoichiometric with the mineral salt added, plus an amount sufficient to neutralize other alkaline substances which may have been added or are already present, plus an amount sufficient to achieve a final pH of between 2.0 and 7.0, and most preferably, a final pH of between 3.0 and 5.0 in the suspension after reaction.

As relates to other additives beneficial to the process or to methods of combining ingredients in order to permit proper dispersion and dissolution of the hydrocolloid in water, it is found that in some cases it is desirable to add sequestering agents to the water in order to chelate metal ions which might interfere with hydration and dissolution of the gum. Agents which are suitable for this purpose, which may be added in any amount up to 0.5%
of the gum solution by weight include the following, used alone or together in combination: sodium or potassium salts of organic acids, phosphates, polyphosphates, metaphosphates, or silicates. Many of these agents create an alkaline reaction, raising the pH to a value greater than 7.0, which is beneficial for hydration and dissolution of the gum. In other cases, cellulose fibers may also first be treated with an alkali or alkaline substance in addition to the preceding, including for example: sodium or potassium carbonates or h~dLu~ides, while also adding detergents or sulphonates in order to pre-soften fibers and to remove acidic impurities, oils or lignin, which might interfere with gumfer formation, or might contaminate the building product formulation to which the gumfer is added. To ensure proper dispersion and dissolution of the hydrocolloid, it is prefer~ble to use powdered or granular forms of the hydro~olloid together with sufficient agitation, or to premix the gum with all or a portion of the fiber source and then add the pre-mixture to water used in the ~rucess, while simultaneously providing a suitable means of agitation of both gum and fiber. Such previously described techniques are known to prior art.

As a specific variation of the process and especially whenever wood fibers cont~in;ng soluble red~l~;n~ sugars including glucose are added to the process, upon addition of mineral salt,an oxidase enzyme such as glucose oxidase, together with a catalase enzyme may be added to convert glucose to gluconic acid. The catalase enzyme decomposes hydrogen peroxide formed during the _ 22 -conversion reaction, which might otherwise poison the oxidase enzyme. Since oxygen is also required for the conversion reaction, it may continuoUsly be added by means of bubbling air through the reaction mixture. The gluconic acid thus being formed, reacts with the mineral salt and hydrocolloid, releasing cations and anions while simultaneously reducing pH in the reaction mixture, causing ions and hydrocolloid to co-precipitate onto cellulose fibers thereby forming a gumfer. In this manner, the addition of acidulant to the process may be avoided as it is provided in a latent form by means of the reducing sugars contained in the cellulose source.

The methods of this invention may be carried out using any suitable tank or vessel of appropriate construction to withstand repeated exposure to the contents of the reaction mixture, and also provided with a suitable means of agitation. The process of this invention may also be carried out in a continuous or semi-continuous fashion, as for example by adding ingredients to a continuous mixer in order of use and in ratios and at rates at which they are needed. After precipitation, gumfers may be transported by means of pumping or gravity flow, and the supernatent fluids may be separated by draining, filtration, and pressing techniques. Gumfers may be washed, dried to a ~ isture content of 10% or less, and reduced in particle size using ~nv~ional methods and equipment known to prior art. Depending on the cellulose source used, and once neutralized to a pH of 7.0 or greater, water exhausted from the process by draining, pressing, or washing, may be recycled to the beginning of the process. Where a natural wood fiber has been used, soluble impurities such as sugars extracted during the process, may be removed by draining, washing, or pressing, or converted to sugar acids using the precedingly described technique.
A continuous method of making gumfers is illustrated by means of Figure I.
With reference to Figure I, in the upper part of the drawing is shown a continuous mixer A and B, to which ingredients charged to the process are added in amounts and in order of use to form a gumfer. The sections of A and B in which individual reactions take place are indicated by means of the dashed lines, and are subsequently numbered in the direction of flow from one section to another. Process water and recycled water are added to section 1 and are mixed uniformly using appropriate mechanical means, such as for ex~mple by means of a bladed shaft which passes through the centre of the mixer, to form a mixture having a temperature of less than 30~C. This mixture then flows into section 2 to which a sequestering agent is then added. The sequestrant being properly dispersed and dissolved in the water mixture, the mixture thus formed having a pH of 7.0 or greater, then flows into section 3. To section 3 is then added a hydrocolloid or a mixture of hydrocolloid and cellulose source, which is similarly dispersed and dissolved. The hydrocolloid solution then enters section 4, and the h~l~nce of the cellulose source is added and similarly dispersed.
The cellulose-hydrocolloid suspension thus formed then flows into section 5 of continuous mixer B. For all intensive purposes, A and B are the same mixer, so that section 5 is merely a continuation of mixer A. To section 5 is then added a mineral salt which is similarly dispersed and dissolved, and the suspension then enters section 6. To section 6 is added an acidulant in order to achieve a pH of between 2.0 and 7.0, and preferably between 3.0 and 5.0 in the final mixture, and the entire suspension contain;ng water, sequestrant, hydrocolloid, cellulose source, mineral salt, and acidulant is thoroughly mixed in section 7 to ensure complete gelling and co-precipitation of ingredients and formation of a gumfer.
A suitable means of agitation and an appropriate residence time within section 7 is provided by means of controlling the rate of flow so that complete reaction may be allowed to take place. The precipitated gumfer suspension, now being at a temperature of less than 30~C and a pH of between 2.0 and 7.0, is subsequently filtered, pressed, washed, dried, and reduced in particle size using appropriate means, as shown in the lower part of Figure I.

As relates to the use of gumfers in building product formulations, whether used in high moisture content form as obtained directly from the process, or whether used in dry, particulate, and particle size reduced form as obtained by drying and size reduction, the gumfers of this invention may be added to building product formulations cont~in;ng cementing agents such as: portland cement, lime, silicates, g-ypsum, or clay, in order to prepare building products using methods precedingly described.

In gumfers prepared according to methods of this invention, cations andanions donated by the mineral salt and acidulant are attached to uronic acid or substituted groups of the hyd~ocolloid, such as phosphyl, sulphate, or carboxyl groups, the hy~r~colloid itself being attached to cellulose fibers by means of hydrogen bonding. When such gumfers are added to building product formulations, the uronic acid sugar residues or the substituted sugar groups, and the cations and anions which are attached to these groups, react with the cementing agent, thereby bonding the hydrocolloid directly to cementing agents used in the formulation, Since the hydrocolloid is itself indirectly bonded to cellulose fibers, the fibers are themselves indirectly bonded to the cementing agent, and in this manner the entire gumfer heco~Qs an integral part of the building product. Since the pH of some cementing agents is greater than 7.0 when mixed with water, for example portland cement or lime, some dissociation of hydrocolloid from the gumfer may occur on mixing gumfer with the cementing agent using water, however this dissociation is localized unless the mixture is excessively agitated. Therefore it is desirable when using gumfers to prepare acqueous cementing mixes, to employ a limited degree of mixing, a temperature of less than 30~C, and to add acidulants to the mixture whenever possible.

It is found that gumfers may be added to building product formulations in an amount up to and including 250% by weight of the cementing agents used, based on dry weight of gumfers cont~;n;ng 10% moisture. The actual amount of gumfer to be employed in any given formulation is dependant on the types of hydrocolloid and cellulose fiber source used, on the ratio of these two ingredients, on the types of cementing agents used, and on particle size of the gumfer and its ability to retain moisture.

When used in dry, powdered, or particulate form, gumfers may be pre-mixed with dry, powdered cementing agents including other fillers and additives as precedingly described, in order to prepare dry building mixes suitable for use as mortars or as patching compounds, or as mixes suitable for casting purposes when rehydrated with water. Alternatively, cementing agents may be added to gumfers which are in a moist state as obtained directly from the ~Lo~Ss, together with water and other additives as previously described, in order to prepare wet mixtures suitable for casting purposes which are designed for on site construction use.

Through the use of other prior art additives as previously described, wet mixtures thus formed may be made more suitable for the preparation -- 25 ~

of various construction products including for example: cement or plaster castings; cement or plaster wallboard or sheathing panels; cement or non-fired clay roofing shingles or tiles; non-fired clay bricks or building blocks; wall-fill, sub-flooring; or acqueous and non-acqueous cement or lime based mortar mixes and grouting compounds. Where it is desired to use such products in exterior and interior applications, they may be suitably water-proofed and fire-proofed using appropriate prior art means such as for example, by coating finished surfaces with plastic resins or with silicate solutions, and by including ammonium phosphates in formulations.

It is found that the formulations and building products made using gumfers prepared according to methods of this invention, possess all those desired imp~uv~.~lts in properties previously described including: workability of wet mixtures; high elasticity and lubricity of fibers; ability of fibers to bind with cementing agents to a controlled and variable degree dependant on hydrocolloid to cellulose ratio, on hydrocolloid type, and on ratio of gumfer to cementing agent; non-weeping of moisture from acqueous mixtures; non-interference with casting, setting, drying, and curing properties; non-shrinkage and non-cracking; no spalling after curing;
and also, low density, high strength, and increased impact resistance of the products compared to products made using prior art methods.

Particularly as concerns workability, gumfers are somewhatlubrous sincethe cellulose fiber has been coated with a gum of highly elastic or rubbery nature. Consequently, when gumfers are added to building product formulations and the mixtures spread by troweling, gumfers do not nest and unlike untreated cellulose fibers, the lubrous nature of gumfers offers little or no resistance to shear.

In cases where hydrocolloids alone are added directly to formulations cont~;n;ng esperi~lly portland cement or gypsum for purposes of attempting to improve the working properties of such mixtures, it is found that setting, drying, and curing properties of such mixtures are severely affected and that often such mixtures will not set or cure for days or even weeks. This does not occur when gumfers are used, and the hydrocolloid has first been precipitated onto cellulose fibers. In other words, except when the alkalinity of cementing agents is high and when gumfers are used at high gum:fiber ratios exceeding 1 : 2, and in relatively high amounts compared to cementing agents used, hydrocolloids do not appear to dissociate from gumfers when added to building formulations, and do not affect setting or curing properties of the mixtures.

The process for preparing gumfers is a low energy process since the methods may be carried out at ambient temperatures between 5~C and 25~C. The process can utilize many waste forms of cellulose including bleached paper pulp or wood chips for example, to which energy has already been added in terms of particle size reduction, or in terms of prior extraction of solubles and impurities in the case of recycled paper pulp. Since gumfers may be used in wet acqueous form as obtained directly from the process, the addition of energy to evaporate residual moisture is not an absolute requirement. Energy requirements for the process are instead in the form of energy necessary to refine ingredients before use in the process including hydrocolloid, mineral salt, and acidulant; however, as may be seen from the disclosure, alternative, unpurified ingredient sources may be substituted and utilized, as for example by using the hydrocolloid in acqueous solution form as obtained during a particular stage of its extraction from natural sources, rather than in a dry, powdered form to which it has been necpss~ry to add additional energy in order to obtain the hydrocolloid in a refined state. Or to give one further example, by using either pulverized, recycled concrete, gypsum, or clay products as the mineral salt as the case may apply, in place of using refined cement powder, plaster of paris, or refined clays, to which energy has been added in order to prepare these ingredients in a refined, hence reactive form.

Since cellulose fibers and hydrocolloids are to be found throughout nature, and are readily extractable and renewable resources, there are few restrictions to the use of such materials in the present invention as long as plant forms continue to proliferate. In fact, these substances are to found together with cementing agents calcium and silicate in practically all plant forms. Therefore, as a refinement of the present invention, it may be stated that the most optimum ratio of ~lydLo~olloid to cellulose to be employed in the invention is that ratio in which these substances are found to occur naturally throughout nature. By the use of such ratios, neither ingredient will be depleted from the environment in an uneven amount compared to the other, and both ingredients would therefore be entirely renewable, thus ensuring continuous supply and availability.

Since both the type of hydrocolloid and cellulose source used, the particle size of the cellulose fiber, the ratio of gum to cellulose, as well as the types and quantities of mineral cations and anions which may be attached to the gumfer can all vary, it is obvious that a wide range in building product formulations is possible. By virtue of such variability, it is possible to obtain a wide range of desirable properties in building formulations and products, and that the use of gumfers in building products leads to an adv~n~ nt in the art of their preparation, incomparable to existing prior art methods. It is believed that the present invention will lead to adv~n~mPnts in the art of preparing building products which are fiber composites, useful for construction purposes.

In the following are given examples of gumfer preparation, illustratingthe variety of ingredient types, concentrations and ratios, processing methods and conditions which may be employed, and also including examples of the use of gumfers in preparing building construction products:

Example 1 Newsprint gumfer using konjac-carrageenin blend, or kappa-carrageenin.

9.0 g of newsprint is cut into ~" squares and added to 325 ml water in a blender. The newsprint is chopped until fine and smooth. ~ g of a proprietary mixture of konjac-carrageenin believed to be in a ratio of 1 : 1 is added with stirring. After several minutes, the mixture is almost gel-like, slimy, and viscous. When 0.2 g of citric acid is added with stirring, the .~l;m;ness and gel-like character of the suspension disappears, the newsprint pulp flocculates and settles out, and the solution surrounding the pulp is clear and water-thin, and is easily decanted, strained, or expressed from the pulp. The expressed pulp feels somewhat rubbery or elastic. Metal ions in the water are believed to assist in precipitation of the gumfer. When the moist gumfer is heated to a temperature of 35 C, the gumfer becomes slimy and gel-like in texture once again, indicating that gum dissociates from fiber. When cooled, the gumfer reverts to a non-slimy, non-gelatinous condition, and the rubbery and elastic nature of the gumfer is restored.

The experiment is repeated using 20.0 g of micro-crystalline cellulose of average particle size 8 microns suspended in 200 ml water. In one case, 1.0 g of kappa-carrageenin without added konjac flour is added, and in another 1.0 g of proprietary mixture of konjac-carrageenin is used instead. When citric acid is added, similar results to the preceding are obtained.

The experiment is repeated using 20.0 g bleached paper pulp of average particle size 35 microns and 5.0 g of kappa-carrageenin suspended and dissolved in 400 ml hard water containing 0.8 g of 60% sodium lactate solution added as a sequestrant. When either potassium or ammonium lactate are added to give O.lN, followed by lactic acid to give 0.05N, similar results to the preceding are obtained. When calcium lactate pentahydrate is used instead, a gumfer is not formed.

The conclusions which may be reached are that either mixtures of konjac-carrageenin or kappa-carrageenin alone are capable of forming gumfers in the presence of either K or NH4 but not Ca , when also in the presence of an acidulant. Other forms of carrageenin including iota forms are expected to react similarly, and also with calcium ion as well, according to their known properties.

Example 2: No gumfer formation with xanthan gum, xanthan-locust bean mixture, welan gum, rhamsan gum, flax gum, carboxymethyl cellulose, or methyl celluloseusing bleached paper pulp.

~ g of 60~/o sodium lactate solution is added to 200 g water at 15~C as a sequestrant. 1.0 g of proprietary mixture of xanthan-locust bean gum believed to be in a ratio of 3 : 2, is mixed with 10.0 g of bleached paper pulp of average particle size 110 microns, and the mixture added to the solution with stirring. A slimy and viscous suspension is formed.
When K lactate is added to give O.lN, followed by lactic acid to give O.lN, a slight thickening effect is noticed, but no precipitation is observed and the suspension remains viscous and slimy. The ratio of gum to fiber employed is 1 : 10.

When the preceding experiment is repeated using xanthan gum only at a ratio of 1 parts gum to 4 parts fiber, and when similar concentrations of either Ca lactate pentahydrate, NH4 lactate, Al lactate, Zn lactate, or Ferrous (II) lactate are added, together with either lactic, glycolic, malic, or phosphoric acid as acidulants, no gelling or precipitation is observed, and similar results are obtained.

The same experiment repeated using either welan gum, rhamsan gum, ~lax gum, carboxymethyl cellulose, or methyl cellulose, with the preceding mineral salts and acidulants used at similar concentrations and ratios, does not produce a gumfer precipitate with either K, Ca, NH4, Fe ,Al, or Zn, and similar results to the prece~; n~ are obtained.

The conclusions which may be reached are that none of the prece~lng gums produces a gumfer with either K ions or multivalent metal cations, excepting xanthan gum which is known to produce a precipitate in the presence of ferric (III) ions at pH values less than 7.0, and ca.~o~y..~hyl cellulose, which is known to precipitate in the presence of either ferric (III) ion or aluminium ion at pH values less than 7Ø

-Example 3: Gumfers prepared using gellan gum.

2.5 g of de-acylated gellan gum is added to ~00 ml water at 5~C containing 0.8 g of 60% Na lactate solution, with stirring in a blender. A clear, adhesive, gUm-liike solution of high viscosity is obtained. 10.0 g of bleached paper pulp of average particle size 110 microns is added and thoroughly dispersed by stirring, to yield a suspension containing 1 parts gum and 4 parts fiber. The suspension remains adhesive and viscous.
7.2 g of 60~~ K lactate to give 0.112N, followed by 6.0 g citric acid to give 0.062N are added with stirring. Upon addition of K salt and acid, flocculation is noticed, and fiber begins to separate from the mixture. After several minutes, the fiber is settled and a clear, non-viscous, non-adhesive supernatent fluid remains apart from the precipitate.
This fluid is water-thin and is easily separated from the fibrous precipitate by filtration. The pulp which is recovered by straining is elastic and rubbery in nature. The precipitate does not retain liquid and is easily expressed to remove free-flowing moisture.

The conclusion which may be reached is that gellan gum forms a gumfer with cellulose fibers in the presence of potassium ions at pH values less than 7Ø The gum is removed from solution and co-precipitated with cellulose fibers by means of hydrogen bonding, presumably also being held in place by potassium ions in a helix type structure, characteristic of gums which gel using either K or Ca ions, including gellan gum, carrageenin, alginates, or agar. The pulpy precipitate is dried to a moisture content of lO.O~o or less and may be ground to a fine particle size. According to the preceding and also according to its known properties, gellan gum is also expected to form gumfers with multivalent metal ion including Ca, Mg, Ba, Fe(II), Fe(III), Al, or Zn.

Example 4: Gellan gumfers made using bleached paper pulp.

Repeats of example 3 are made employing 5.0 g gellan gum and 20.0 g bleached paper pulp, or a gum:fiber ratio of 1:4, dissolved and suspended in 800 ml water at 20~C, containing 0.8 g 60~o Na lactate, and also employing different variables in three separate trials:

Trial 1: K lactate followed by lactic acid are added to give O.lN ofeach substance. The suspension thins immediately on addition of lactic acid, and flocculation of fiber is noticed. Calculation of theoretical pH
using the Henderson-Hasselbach equation gives pH 3.08. The supernatent fluid is clear, thin, non-adhesive, and non-viscous in nature. The gum-fiber composite is removed by straining to yield 510 ml of supernatent, and when the gumfer is also pressed, a total of 760 ml expressed fluid is obtained, representing 95% of the original water used in the process. ~ of this fluid or 400 ml is recycled to the subsequent trial.

Trial 2: To 400 ml of make-up water plus 400 ml recycled fluid from trial 1 to give a total of 800 ml fluid at a temperature of 18~C, are added similar amounts of gellan gum and paper pulp as used in trial 1.
K lactate to give 0.05N, followed by 2.0 g of sodium silicate solution cont~;n;n~ 37.6% solids consisting of SiO2:Na20 in a ratio of 3.22:1; are added with stirring, followed by lactic acid with stirring to give 0.05N.
Coarse flooculation results on addition of lactic acid. Results are similar to trial 1, and a gumfer is formed. The supernatent fluid is easily recovered from the precipitate by straining and pressing, and 400 ml of supernatent is recycled to a subsequent trial.

Trial 3: 400 ml recycled fluid from trial 2 is added to 400 ml make-up water to give 800 ml total liquid at 20~C. Na lactate, gellan gum, and paper pulp are used at levels as in trial 2. 4.0 g of calcium lactate pentahydrate is added, followed by 5.0 g of 85% lactic acid with stirring.
An extremely coarse flocculate and precipitate is formed which is easily strained and pressed. The expressed liquor is clear, non-adhesive, and non-viscous in nature.

The conclusions which may be reached are that gellan gum forms gumfers in the presence of either K or Ca ions at high H ion concentration or at pH
values less than 7Ø

Example 5: Gellan gumfers and construction products made using portland cement and various fiber sources.

Trial 1: The following are added to a blender with stirring, in order of use: 900 ml water at 20~C/ 6.0 g Na silicate solution, 5.0 g gellan gum, 25.0 g bleached paper pulp of average particle size 100 microns to give a gum:fiber ratio of 1:5~ followed by 10.0 g portland cement powder as the mineral salt, pre-blended with 6.0 g fumaric acid as the acidulant.
Approximately 5-10 minutes after addition of cement-fumaric acid blend, gelling is noticed. After several additional minutes stirring, gel texture brea]cs down and gross flocculation is noticed. The supernatent is clear, non-viscous, and non-adhesive in nature. An additional 10.0 g cement powder is added to the suspension with stirring, and the mixture is strained and pressed to yield a cake ~" deep by 4" square, containing 34% solids. The cake surface is coarse and fibrous, and difficult to smooth. The cake is allowed to dry and harden. When sufficiently dry, a lightweight board is obtained which is suitable to be used as a wall covering material. The solids content of this board is approximately 65 parts gumfer per 100 parts, of which approximately 52 parts is gum plus cellulose, 3 parts is silica, and 5 to 10 parts is fumaric acid. 35 parts of the total solids content in the cake is cement powder, hence the ratio of gumfer to cement powder in the product is 1.86:1~ or 186~o by weight of the cementing agent added.

Trial 2: A repeat of trial 1 is made using similar amounts of water,gellan, Na silicate, cellulose, except that a fiber particle size of 35 microns is used instead. A mixture containing 20.0 g cement powder and 6.0 g fumaric acid is added, followed by 40.0 g dry sand. A precipitate forms, and the suspension is drained and pressed into a wet cake weighing 190 g cont~;n;ng 48.6% solids by weight. The cake is easier to shape and to smooth than in trial 1, and when sufficiently dry, is suitable for use as a wall covering material. The solids content of the board is approximately 38~ parts gumfer per 100 parts, of which approximately 30.7 parts is gum - 33 ~

plus cellulose, 1.7 parts is silica, and 6 parts is fumaric acid. 20~ parts is cement powder, and 41 parts is sand, hence, the ratio of gumfer to cementing agent in the product is 1.93:1, or 193% of the cementing agent used.

Trial 3: A repeat of trial 2 is made, employing similar amounts of gum, silicate, and fiber, but lesser amounts of cement and sand. Microcrystalline cellulose is used as the fiber source, with average particle size 20 microns.
Similar results are obtained, except that the dried cake contains approxi-mately 45.3 parts gumfer per 100 parts, of which approximately 38~ parts is gum plus fiber, ~ parts is silica, and 5~ parts is fumaric acid. 18 parts of the solids content is cement powder, and 36~ parts is sand, therefore, the ratio of gumfer to cementing agent used is nearly 2.5:1~ or 250% by weight of the cementing agent employed.

Example 6: Alginate gumfer 400 ml of water at 20~C containing 0.8 g of 60~o Na lactate is charged to a blender. 5.0 g of a grade of sodium alginate, a 2% solution of which produces a viscosity of 2~000 centistokes per second, is premixed with 20.0 g of bleached paper pulp of average particle size 35 microns, and the mixture is added with stirring, to give a gum:fiber ratio of 1:4. The addition of K
lactate, followed by lactic acid, to give O.lN of each substance with stirring, does not yield a flocculate or precipitate. When the experiment is repeated using Ca lactate pentahydrate instead to give O.lN with stirring, an immediately gelling effect is noticed. When lactic acid is subsequently added with stirring to give O.lN, gelling is initially enhanced followed by th;nning of the suspension and flocculation of fiber. On stirring, gel texture breaks do~n, and a precipitate is formed. The super-natent fluid is clear, non-viscous and non-adhesive in nature. The preci-pitated gumfer is easily strained and pressed, and may be dried to a moisture content of 10% or less, then finely ground to a free-flowing powder.

The conclusion which may be reached is that sodium alginates form gumfers with cellulose fibers in the presence of calcium ions but not potassium ions, when also in the presence of high H ion concentration, or pH values less than 7Ø Alginates are, therefore, also expected to form gumfers in the presence of other multivalent ions, including Mg, Al, Fe, Zn, but not with monovalent ions according to their known properties.

Example 7: Alginate gumfer m--ade using K silicate, Ca carbonate, and NH4 phosphate as mineral salts.

To 900 ml water at 20 C is added with stirring, 12.0 g of K silicate solution containing 30~/O solids in a SiO2:Na2O ratio of 2.5:1, and 100 g of a mixture of 80 g microcrystalline cellulose and 20 g of a low viscosity grade of sodium alginate in a ratio of 1 parts gum to 4 parts cellulose fiber. The acqueous mixture thus formed is stirred for several minutes to yield a viscous and adhesive suspension. To the mixture is then added with stirring, 12g finely powdered calcium carbonate, followed by 7 g ammonium monophosphate predissolved in 50 ml water, followed by 32 g of 75% phosphoric acid solution prediluted in 50 ml water. Upon addition of acidulants, immediate gelling is noticed, followed by t,~;nn;ng, flocculation, and precipitation of a gumfer. The precipitate may be recovered by straining and pressing, and may be dried to a moisture content of 10% or less, then finely ground to a free-flowing powder. It is noticed that this particular gumfer is fracture-resistant and more difficult to grind than gumfers formed using other types of mineral salts.

Example 8: Alginate gumfer and construction product made using portland cement and Na silicate as mineral salts.

The method of examples 6 and 7 is repeated, using the following quantities of ingredients added to 1 litre of water at 20~C in order of use: 6.0 g Na silicate solution; 6.0 g of high viscosity Na alginate preblended with 30.0 g bleached paper pulp of average particle size 100 microns; 4.0 g portland cement powder preblended with 6.0 g fum~ric acid or gluco-delta-lactone is added with stirring. Within 30 seconds after addition of mineral salt acidulant mixture, gelling is noticed and gel texture reaches a m~ m after approximately 5 minutes. On continued agitation, gel texture is noticed to break down, and within an additional 10 minutes, the mixture berom~s thin and slurry-like, and coarse flocculation and 21 ~ 1 002 precipitation of fiber is noticed. To the mixture is then added 54 g portland cement powder and 120 g dry sand. The mixture is strained to remove super-natent which is clear, non-viscous, and non-adhesive. The recovered pulp is pressed to yield 430 g of cake containing 52% solids. To the cake is then added an additional 20 ml water and 5 g cement powder preblended with 1.0 g xanthan gum, and all are mixed to a desired consistency. The resulting cake is then formed into slabs ~" thick by 41' square, and allo~ed to set, harden, and dry. After drying, the slabs contain approximately l9. 6 parts alginate gumfer per 100 parts, of which approximately 13~ parts is cellulose, 2.7 parts is gum, 0.8 parts is silica, and 2.7 parts is fumarates or gluconates.
The cement content of the cake is 26. 8 parts and the sand content 53.6 parts.
Hence, the ratio of gumfer to cementing agent used is 0.73:1~ or 73% of the cementing agent used. The dried slabs are suitable for use as panelling materials. The ratio of gu~ to cellulose in the alginate gumfer is 1:5.

Example 9: Gellan gumfers used in portland cement castings.

1) 20.0 g of dry powdered gellan gumfer prepared according to methods of example 5~ and containing approximately 60% bleached paper pulp of particle size 100 microns, 15% gellan gum, 12% portland cement powder, 11% fumarates, and 3% silica, and in a gum to fiber ratio of 1:4, is preblended with 40 g of portland cement powder and 120 g dry sand, to yield 180 g of a dry building product premix. To this premix is then added 150 g water with stirring, to yield 330 g of a paste containing 541~o/o solids. The mixture is of suitable consistency to permit casting into molds. The mixture is tamped down into a tube to form a cylinder 2" in diameter by 2" high, and the casting is allowed to set, harden, and dry. During setting, 5.0 g of excess moisture weeps from the surface of the casting and is decanted, leaving a solids content of 55~% in the mixture. The density of the casting when dry is 1.08 g/cc, compared to a similar casting of ordinary portland cement made using only 75 g water added to 180 g cement powder without additives, of density 1.73 g/cc. As the gumfer casting contains 11.1% gumfer, 22.2% cement powder, and 66.6% sand, the ratio of gumfer to cementing agent used is 0.5:1, or 50~O by weight of the cementing agent used. The casting is hard, fracture resistant, and durable. No spalling of components from the surface of the casting is evident.

2) The preceding experiment is repeated using the same cellulose fiber source, but left untreated, using the same proportions of fiber:cement:sand.
To 180 g of premix it is found necessary to add 180 g water to form a wet mixture of comparable consistency, hence an excess of 30 g water compared to the preceding example. The mixture, totalling 360 g conta;ning 50~/O solids is similarly molded and allowed to set, harden, and dry. ~uring setting, 60 g of water weeps from the surface of the casting and is decanted. After drying, the casting has a density of only 1.03 g/cc, but is not as hard and fracture resistant, and spalling of components from the surface is noticed.

In comparing the two castings, the gellan gumfer casting is judged to be superior both in strength and appearance, and also possesses a comparable density which is much lesser than that of portland cement or cement-sand-castings which do not contain cellulose fibers.

Example 10: Cement products prepared using alginate gumfer.

An alginate gumfer of gum to fiber ratio 1 to 5 is prepared, according to methods of preceding examples. Ingredients are added in order of use, in the following proportions: 3.6 litres water at 20~C; 3.2 g of 60% Na lactate solution; 160 g of microcrystalline cellulose of average particle size 50 microns; and 32.0 g of high viscosity sodium alginate gum. To the suspension is then added 24.0 g of portland cement powder with stirring, follo~Jed by 560 ml of vinegar solution cont~;n;ng 5% acetic acid by volume.
After flocculation and precipitation of gumfer, the gumfer is strained and pressed to yield a cake conta;n;ng 50~/O moisture. The cake is crumbled and spread out to dry. After drying, the gumfer is finely ground to a free-flowing powder and a faint odour of vinegar is detected. The dried gumfer powder is used to prepare cement castings in the following manner:

A dry premix of each of the following formulas is made:

21qlO02 -Formula 1 2 3 4 Dry powdered gumfer 10 20 30 40 Perlite 30 20 10 nil Welan gum 0.5 0.8 1.1 1.4 Portland cement powder 60 60 60 60 Total parts dry mix: 100.5 100.8 101.1 101.4 by weight Welan gum is added to give a desired consistency to acqueous mixtures, in order to retain shape and texture when foamed or aerated.

Then, to each mixture is added with stirring, suitable quantities of water, 6% hydrogen peroxide solution, and a catalyst to decompose the peroxide solution into oxygen and water.

Water 110 110 120 140 6% Hydrogen peroxide 10 10 10 10 Catalyst 0.5 0.5 0.5 0.5 Total parts by weight: 221.0 221.3 231.6 252.5 Upon addition of catalyst, foaming results, and the mixtures are observed to expand greatly in volume. The foamed and expanded mixtures are cast into the form of cylinders 4" in diameter by 2" high, and allowed to set, harden, and dry. Mixtures are observed to retain their shape and volume after setting.
Following are the comparative results obtained:

Formula 1 2 3 4 % Solids in wet mix 45~ 45~ 43~ 40 Ratio of gumfer to cement0.17:1 0.33:1 0.5:1 0.67:1 Density of Wet Mix, g/cc: 0.98 0.83 0.87 0.83 Dry Density of Castings, g/cc: 0.49 0.42 0.42 0.37 All castings after being suitably dried, are resistant to fracture, possess desirable surface hardness, and do not exhibit spalling. The casting of formula 1 has a tendency to shrink and crack while still moist and after setting. Formula 4 requires a longer period of time to set and dry. Formula 3 is judged to be superior in terms of density, setting and drying properties, and in strength and appearance.

_ 38 -It is observed that the final densities of products made according to the preceding methods are substantially lower than those obtained using portland cement or concrete castings without added cellulose fibers. For example, thel density of a portland cement casting is determined to be 1.73 g/cc. Hence the castings of this example are only 25% or ~ that of cement castings, and all examples are lighter than water. When sealed with epoxy resin, gumfer castings of this example are observed to float on water, and may be used as flotation devices or as boat construction materials.

Example 11: Wood fiber/algin gumfer, made with mineral salts: potassium silicate, tri-calcium phosphate, and ammonium monophosphate. Used to prepare cement construction products.

1) Gumfer preparation:
Lodge Pole Pine fiber is obtained from forestry cutting and mill waste in the form of coarse splinters. The fiber is sifted to remove large splinters and to obtain a material of more uniform fiber length approximately 1/8" long.
40.0 g of sifted fiber is pre-mixed with 10.0 g of a low viscosity grade sodium alginate to give a premix cont~;n;ng 1 parts gum to 4 parts fiber. The premix is then added to 750 ml water at 20~C containing 6.0 g of a K silicate solution, with stirring. The pH of the suspension after 15 minutes is determined to be 9.8. To the suspension is then added 6.0 g tricalcium phosphate powder. The pH after 5 minutes stirring is determined to be 9.7.
3.0 g of ammonium monophosphate is next added with stirring, and after 5 minutes, the pH is determined as 6.6. The suspension remains viscous and gum-like, and no flocculation or precipitation is noticed. 6.0 g of 75%
phosphoric acid solution is then added with stirring, and immediate gelling, followed by flocculation is noticed. After 5 minutes additional stirring, a supernatent fluid is obtained which is clear, non-viscous, and non-adhesive in nature. The pH of this fluid is determined to be 3.3.

The wood fiber-algin gumfer is recovered by straining and pressing, and the gumfer is elastic and rubbery in nature. The gumfer is dried to a moisture content of lO~o or less and is ground to a free-flowing solid of fiber length comparable to that of the original material before precipitation. The dried gumfer is used to prepare a cement product in the following manner.

2) Preparation of Cement Castings using wood fiber gumfer:
10 parts of dry, free-flowing wood fiber gumfer is preblended with 60 parts portland cement powder to yield 70 parts premix. 50 parts of water is then added to the premix with stirring to form 120 parts of a paste of suitable consistency to be spread or to be packed into molds. The wet mixture contains 58.~/o solids, of which approximately 14.3 parts per 100 parts is wood fiber gumfer and 85 . 7 parts is cement, hence the ratio of gumfer to cementing agent in the product is 1:6, or 16.7% of the cementing agent used. The acqueous mixtures are cast into the shape of this discs, 4" in diameter by ~" thick, and allowed to set, harden, and dry.

3) Preparation of cement castings using untreated wood fiber:
A comparison of gumfer castings with castings made using untreated fiber, is carried out in the following manner:
10 parts of untreated sifted Lodge Pole Pine fiber is pre-mixed with 60 parts portland cement powder, and to the premix is then added 50 parts of water with stirring. The wet mixture, therefore, contains a similar proportion of ingredients, except that it has a slightly higher cellulose content. This mixture is similarly cast and allowed to set, harden, and dry. 7 parts of water are observed to weep from the surface of the casting during setting and are subsequently decanted.

4) Portland cement castings without added fiber:
A comparison with portland cement castings without added gumfer or wood fiber is made in the following manner:
To 120 parts of portland cement powder is added 50 parts water with stirring to form a paste of comparable consistency to the preceding examples, contain-ing 70~~/O solids by weight. This mixture is similarly cast and allowed to set,harden, and dry.

A comparison of all three castings yields the following results:

Casting Example 1 2 3 Wood fiber gumfer - Untreated Wood Portland Cement fiber without additives Property Observed Setting Time 12-24 hours 48 hours 12-24 hours Workability viscous, spreads viscous, fibers thin, pours, well, casts well i nest, more easy to spread difficult to and also to spread and cast cast Moisture retention no weeping weeps some weeping Spalling none severe none Surface finish mostly smooth irregular, excellent, chipped smooth Dry density of casting, g/cc: 1.15 1.03 1.73 When the castings of examples 1 and 2 are soaked under water for several weeks, no change in the gumfer casting is apparent; however, the casting containing untreated wood fiber of example 2 is noticed to disintegrate, and water insoluble impurities float to the water surface.

It is seen from these results, that gumfer castings are comparable to cement castings, with the exception of density which is al ~ st 40~0 less, and are superior to castings made using untreated wood fibers.

,,j~

21qlO02 Example 12: Wood fiber-algin gumfer and its use in preparing cement based construction products.

Lodge Pole Pine wood fiber which is a mixture of fine sawdust and coarse splinters up to 1/8" in diameter by 1" long, is used to prepare a gum-fiber composite as follows:
To 15L water is added 10 g of 30~~O potassium silicate solution as a sequestrant.
The pH of the solution is measured as 9.8. 85 g of a dry powdered sodium alginate, a 2~o solution of which has a viscosity of 500 cps, is dry blended with 65 g of a sodium alginate, a 2% solution of which has a viscosity of 160 cps, to yield 150 g of a mixture of sodium alginates. The mixture is then blended with 150g wood fiber and the resulting mixture added to the solution with stirring. 600 g of additional wood fiber is then added with stirring, to yield a suspension cont~;n;ng 750 g wood fiber and 150 g alginates, or a gum : fiber ratio of 1 : 5. The suspension is stirred for an additional 15 minutes to ensure complete hydration of gum and wood fiber. The pH after 15 minutes is determined to be 7.7, and the suspension is viscous and adhesive in nature.

100 g of portland cement powder slurried in 200 ml water, and serving as the mineral salt, is added to the suspension with stirring. After stirring for 20 minutes to ensure hydration of the powder and partial reaction with alginates, the pH is measured as 11.7, and the suspension is nearly gel-like. 140 g of 75% phosphoric acid solution diluted in 1 liter water is then added slowly with stirring, and the pH is determined after various time periods. The initial pH after addition of acidulant is 5.0; 5 minutes later, the pH is 4.7; after 10 minutes, the pH is 5.4;
at 15 minutes, 5.8; and at 20 minutes, 6Ø

Upon addition of acid, the gel texture of the suspension breaks, the suspension thins, and the wood fiber is noticed to flocculate but remains suspended and settles slowly. It is concluded that the acid reacts with the cement powder and alginate to produce a solution containing sodium and calcium phosphates which are water soluble, hence act as buffering agents. The supernatent fluid is non-viscous and non-adhesive in nature, and is easily separated from the gumfer by draining. The gumfer is pressed to a moisture content of approximately 50% by weight, and almost all the original water added may be recovered as a liquor. m e expressed gumfer is dried to a ~ isture content of less than l~/o by weight, and is not reduced in particle size before use in preparing a construction product.

The preceding experiment is repeated using an additional 750 g wood fiber and 150 g mixed alginates, to yield a total of 1955 g of dried wood fiber gumfer, or a yield of 88.5% based on total solids and acidulant charged to the process. The loss in yield is presumed to be due to water soluble impurities in the wood fiber such as sugars, which are lost in th~ process water after expression. The dried gumfer is used to prepare cement based construction products as follows:

Trial A: 1,200 g of dried wood fiber gumfer is blended with 6,800 g of portland cement powder. To the mixture is added 5 L water with stirring to form 13,000 g of a smooth paste of barely pourable consistency. This mixture is noticed to spread well, and may be cast. 11,000 g of this mixture is tamped down into a mold having dimensions characteristic of a typical concrete building block, and the casting is allowed to set and harden. The casting is notice; to set or gel within 6 hours, and may be stripped from the mold after 12 hours. After stripping and drying, the casting has a density of only l.l5 g/cccompared to concrete products which have densities of 2.5 to 3.0 g/cc, and weighs only 16 lb or 7.3 Kg, compared to an ordinary building block made of concrete which weighs 45 to 50 lbs, or 20 to 23 Kg. The gumfer castingappears strong and durable, is fracture resistant and water-proof, and the surface finish is smooth and no spalling is apparent.

Trial B: Cement castings in the shape of small discs approximately 4"
in diameter, containing wood fiber gumfer are prepared using the pre~eding method, and D unts of water added, dry densities, and other characteristics are determined.

21~1002 Results of cement-fiber castings, trial B:

Test # Gumfer Cement Total Water Total Cement to Water to Casting Solids Added Wet Mix Gumfer Ratio Solid Ratio Volume Density (g) (g) (g) (g) (g) (cc) (g/cc) .

1 10 90 100 50 150 9 : 1 0.5 : 1 102 1.2 2 20 80 100 74 174 4 : 1 0.74 : 1 121 0.98 3 30 70 100 100 200 2.33 : 1 1 : 1 163 0.72 4 40 60 100 110 210 1.5 : 1 1.1 : 1 193 0.61 100 134 234 1 : 1 1.34 : 1 217 0.54 6 62.5 37.5 100 112.5 212.5 0.6: 1 1.125: 1 257 0.45 7 20 80 100 75 175 4 1 0.75 1 123 0.94 All mixtures containing 20% gumfer or less are pourable and spread well, including the casting of trial A at 15% loading. All castings set within 6 hours and may be stripped after 12 - 24 hours. Castings containing up to 30%
gumfer have a mostly smooth surface finish of hardened cement. All casting mixtures cont~;n;ng 30% or more gumfer are difficult to spread and must be pressed into molds and require longer periods of time to dry. At 30% or greater gumfer loading, fibers are visible on surfaces after hardening.
Castings containing up to 40~/0 gumfer are strong, durable, fracture resistant, and water-proof. At 50~0 and higher gumfer loading, castings are more fragile but integral, and fibers can be dislodged from surfaces. A loading of 62.5%
appears to be the maximum permissable in which fibers are still coated with cement powder and the casting has a reasonable degree of integrity, without falling apart. Example 6 could be used as a wall fill material, which owing to its low density, would have superior heat insulation qualities. Examples 1 and 2 can be used for load bearing applications, for example to replace concretebuilding blocks. & ch pLU~I S Will similarly ~oss~s low densities and high heat insulation ~alues. Casting example 7, containing untreated wood fiber, when compared to example 2, exhibits a longer period of time before setting and hardening, weeping of ~ isture from wet mixtures, sp~ n~ of surface c~on~nt a lesser degree of moisture resistance, and a greater degree of susceptibility to fracture on impact.

Example 13: Use of gumfers in gypsum plaster based castings.

A variety of gumfers prepared according to preceding examples and obtained as dry, free-flowing particulates, are blended with plaster of paris in various ratios. The mixtures are sifted into a pre-determined quantity of water and allowed to soak for 2 minutes. All samples are then mixed by hand for 3 minutes, then cast into containers in the shape of flat discs approximately 4~ round by ~" to 1" thick. The castings are allowed to set and harden, and are stripped from the molds and allowed to dry. A comparison of various characteristics of wet mixtures and properties of castings is made.

Test # Gumfer Type Plaster Gumfer Total Water Water to (g) (g) Solids Added Solids Ratio (g) (g) 1 Kappa-carrageenin, 60 10 70 62 0.886 precipitated onto 35 micron alpha-c*llulose, using K and lactic acid 2-1 Alginate, precipitated 60 10 70 50 0.714 onto 50 micron micro-crystalline cellulose, 2-2 using cement and acetic 55 15 70 50 0.714 acid-3 Gellan, precipitated 60 10 70 70 1.0 onto 100 micron alpha-cellulose, using cement and fumaric acid.
4-1 Gellan, precipitated 60 10 70 50 0.714 onto 35 micron alpha-4-2 cellulose, using 55 15 70 60 0.86 calcium sulphate, 4-3 sodium silicate, and 15 5 20 30 1.5 fumaric acid.
5-1 Gellan, precipitated 60 10 70 62 0.89 onto wood fiber, using 5-2 K lactate, Ca sulphate, 52 18 70 80 1.14 and fumaric acid.

Table, continued:
6 Gellan, precipitated 55 15 70 76 1.09 onto 35 micron alpha-cellulose, using Ca lactate, lactic acid.

7 Alginate, precipitated 60 10 70 50 0.714 onto 35micron alpha-cellulose, using Ca lactate, lactic acid.

The preceding are compared with plaster castings made using untreated alpha-cellulose fibers and also with plaster castings containing no additives.

8 35 micron alpha- 44 12 56 56 1.0 cellulose only.

9 100 micron alpha- 46 7~ 53.5 60 1.15 cellulose.
plaster only 100 - 100 60 0.6 11 plaster only 70 - 70 40 0.57 12 plaster only 70 - 70 50 0.714 Mixtures are compared for workability, weeping, and setting time.
Castings are compared for shrinkage, cracking, hardness, surface finish, and dry density.

Casting Workability Setting Weeping Shringage Surface Hardness* Dry Density Example Time Finish (minutes) (g/cc) _ 1 spreads well 7 none nonegood, no VS 0.82 stiffens on spalling mixing, pourable.
2-1 very good,20 slight none as above H 0.94 casts similarly to plaster.
2-2 as above 13 slight none as above H 0.85 3 stiff paste, 8 none none as above S 0.77 foam-like, casts well 4-1 as above 11 slight none as above H 0.96 4-2 as above 15 slight none as above MH 0.75 4-3 as above 15 none none as above VS 0.57 (strips first) 5-1 as ahove,17 none none as above S 0.68 spreads well, casts well.
5-2 stiff, foamy, 20 none none as above S 0.54 difficult to cast, but spreads well.
6 Stiff paste, 6 none slight as above S 0.66 non-pourable 7 Smooth paste, 10 slight none as above H 0.88 casts well 8 stiff, nests 10 yes, slight chalky VS 0.77 difficult to pour badly.
g very stiff, 6 as above yesv. chalky VS 0.68 as above slurry, 7 yes none excellent H 1.10 casts well 11 as above 7 yes none excellent VH 1.15 12 as above 7 yes none excellent H 0.94 * Hardness: V = very; S = soft; M = moderately; H = hard, according to fingernail scratch test. - 47 -In comparing results of these examples, it can be seen that in some cases gumfers do not affect setting time, workabilty is good to excellent, and little or no weeping and shrinkage occur. It is noticed that the integrity of gumfer-plaster castings is better that of castings containing untreated cellulose fibers, and that the surface finish and hardness are in some cases comparable to that of plaster castings, and that the final densities are considerably lower. Most gumfer castings can be clean fractured by scoring with a knife, and allow penetration of fasteners without fracture.Hence, many of the preceding gumfer castings can be used as wall boards or sheathing materials. It is obvious from the preceding results, that a wide range in properties of gumfer castings may be obtained, by varying the types of hydrocolloid, cellulose source, mineral salt, acidulant, and the amounts of gumfer used in any particular formula.

It is noticed that in cases where gumfers are prepared using potassium salts, that setting and hardening of plaster mixtures is in some cases accelerated.
In cases where fumaric acid or organic acids are used as acidulants in gumfer preparation, residual amounts of these are noticed to contribute to foaming and aeration of the plaster mixtures, due to reaction with calcium and magnesium carbonates which are also present in the dry plaster powders. This effect is of course beneficial to reducing final density, and to obta;n;ng light weight castings of superior insulating value.

Claims (9)

1) A process for preparing cellulose gum-fiber composites or gumfers suitable for combination with cementing agents for use in building construction product formulations, which comprises suspending a cellulose fiber source in an acqueous hydrocolloid solution to which a sequestering agent or alkaline substance has been added by means of stirring, at a temperature of less than 30°C and at a pH of 7.0 or greater, then adding a mineral salt with stirring, then adding an acidulant with stirring, in order to achieve a final pH of 7.0 or less, thereby causing gelling and hydrogen bonding of hydrocolloid onto cellulose fibers, these substances then altogether precipitating out of solution as a gum-fiber composite.

2) A process according to claim 1), wherein the cellulose fiber source contains at least 50% by weight as cellulose and is derived from one or more of the following sources, used alone or together in suitable combination: wood chips, sawdust, bark, newsprint, boxboard, bleached or unbleached paper pulp, plant stalks or straws, seed hulls, fruit fibers, soyabean fibers, sugar cane bagasse, sugar beet pulp, apple, grape, or tomato pomace, grass clippings, leaves, seaweeds, alpha-cellulose, micro-crystalline cellulose, or hemi-cellulose.

3) A process according to claim 1), wherein the hydrocolloid is a mostly linear water soluble polycarbohydrate containing uronic acid sugar residues or phosphorylated, sulphated, or carboxylated sugar residues, and may consist of any of the following, used alone or together in suitable combination:alginates, agar, carrageenin, dextran sulphate, gellan gum, de-esterified gum ghatti, low methoxyl content or de-methoxylated pectin, phosphorylated, sulphated, or carboxylated forms of amylose starch, konjac flour, welan gum, rhamsan gum, guar gum, locust bean gum, or cereal beta glucans, and is also xanthan gum when the mineral salt used is a ferric salt containing iron (III) ions, and is also carboxymethyl cellulose when the mineral salt used is a ferric or an aluminium salt, and is also used together in combination with other hydrocolloids.

4) A process according to claim 1), wherein the mineral salt used is a calcium, magnesium, barium, iron, aluminium, zinc, ammonium, or potassium salt of an oxide, carbonate, sulphate, nitrate, phosphate, phosphonate, borate, flourite, fluosilicate, silicate, or a mixed metal carbonate, phosphate, or silicate, in meta, ortho, or pyro forms as the case may apply, and is also portland cement, gypsum, lime, limestone, dolomite, talc, silica, or clay, and is also a mineral salt containing other cations of the periodic table of elements, including: lithium, beryllium, zirconium, titanium, cobalt, chromium, manganese, nickel, copper, silver, lead, cadmium, mercury, gallium, germanium, tin, cerium, cesium, or bismuth, and is also the metal salt of an organic acid, all used alone or together in suitable combination.

5) A process according to claim 1), wherein the acidulant is a monophosphate salt of an alkali metal of column 1(a) of the periodic table of elements, or of an alkaline earth metal of column 2(a) of the periodic table of elements, and is also ammonium monophosphate, and is hydrochloric acid, sulphuric acid nitric acid, phosphoric acid, phosphorous acid, phosphonic or etidronic acid or organic derivatives of phosphoric acid, boric acid, silicic acid, a sulphonic acid, carbonic acid, and is an acidic oxide of a non-metallic element including nitrogen, phosphorus, and boron, and is an organic anhydride or acid, and is an organic or inorganic substance which reverts to an acid form when dissolved in water, including glucono-delta-lactone, sodium or potassium monocitrate, carbon dioxide, all used alone or together in suitable combination.

6) A process according to claim 1), wherein the precipitated gum-fiber composite in a moist or acqueous state is combined with a cementing agent including: portland cement, magnesium or aluminium cement, water soluble silicate, lime, limestone, gypsum or calcium sulphate, or clay, all used alone or together in suitable combination with other additives, for purposes of preparing building construction products.

7) A process according to claim 1), wherein the precipitated gum-fiber composite is washed, drained, filtered, or pressed to remove free-flowing moisture, and is dried to a moisture content of 10% or less, and is reduced in particle size, and is then combined with dry cementing agents together with other additives, for purposes of preparing building construction products.

8) A process according to claim 1), wherein the temperature of the hydrocolloid-cellulose suspension is between 5°C and 25°C, and the final pH is between 3.0 and 5Ø

9) A process according to claim 1), wherein the ratio of gum to cellulose source is from 1 parts gum to 20 parts cellulose source, and 1 parts gum to 2 parts cellulose source.