TECHNICAL FIELD

The present invention relates to methods and compositions for the application or placement of cementitious compositions which do not require premixing with water. This invention also relates to a method of mixing materials. One particular aspect relates to a method of mixing or combining cementitious materials, but the mixing or combining of other materials are also within the scope of this invention.

BACKGROUND OF THE INVENTION

In the manufacture of dry cementitious compositions, two types of mixing are used. The various ingredients used to form the compositions are combined by dry blending or other dry mixing techniques. Such techniques include the use of mixing equipment having a rotary screw, or blades or baffles rotating in a stationary housing, or those having a rotating or "tumbling" housing with blades or baffles fixed therein. The dry ingredients are thus combined to form a uniformly mixed or homogenous dry composition. Thereafter, these conventional dry compositions are supplied to a job site in bag or bulk form, and are prepared for installation by mixing with water to hydrate the cementitious components so that the mixture can cure to a solid mass. Cementitious compositions can also be prepared by mixing the individual ingredients, such as cement, sand and some type of aggregate, and an aqueous fluid, such as water, by hand or with some type of mechanical mixer. In any event, the individual ingredients

must be thoroughly co-mingled and wet mixed with the proper amount of water to hydrate the dry components so as to provide a final cementitious composition with the requisite 5 integrity for commercial use.

While hand mixing can prove to be a most effective way of attaining a cementitious product of proper composition and integrity, the labor and manpower involved have compelled most workers to resort to automated mixing

^0 devices. These devices, however, have the disadvantage of being complex and requiring great expenditures of money to supply the energy required for routine operation. In addition, since these devices usually include grinding, blenders or other types of mixing components, the ordinary

. _j c wear and tear of these parts minimize the effective longevity of the device. Naturally, the worn-out parts could be replaced, but this would require further expenditures of money and could result in machine shutdown time.

₃₀ In recognizing the need for a more cost-effective and practical mixing device, U.S. Patent Nos. 722,782; 1,029,126; 1,047,680; 1,107,237; 1,473,990; and 4,175,867 each disclose a device for mixing concrete wherein the mixing occurs through a combination of gravitational forces, the structural arrangements of the devices and/or the introduction of pressurized or unpressurized water. Similarly, U.S. Patent No. 1,920,463 describes a method of manufacturing artificial sandstone wherein all of the mixing is done by spraying under pressure and where the

₃₀ materials are mixed while freely falling from elevated hoppers directly into the molds defining the contour of the finished product; and U.S. Patent No. 2,138,172 discloses a batching apparatus wherein a combination of gravitational forces and specially designed baffle means contribute to

₃ _ the batching of the individual components.

At present, it is essential that all dry cementitious compositions are mixed with water before placement in order to obtain the proper characteristics of the final product. 5 Some type of mixing is and has always been required. Some manufacturers of premixes have put the dry premix in a hole and then recommended adding the water. Some have put premixes in bags and dropped the mixes while in bags through the water, then after the bags are in place, 0 letting water penetrate through the bag to the mix.

However, these systems have not allowed full hydration of the cementitious components. Mortar mixers, concrete mixers, hand mixing or other types of wet mixing have been utilized to obtain a uniform distribution of the 5 appropriate amount of water in the cement. According to the prior art, the quantity of water to be mixed with the cement must be controlled to a very narrow range, and too little or too much water will produce an ineffective or unusable material. Cementitious mixtures could not be _Q placed in a dry state directly into water or upon a wet surface without first wetting and mixing the dry components.

SUMMARY OF THE INVENTION ₅ The present invention relates to dry cementitious compositions which have finely divided particles of at least one cement binder. The cement may be Portland cement, gypsum, high aluminum cement, or mixtures thereof, but not restricted thereto. Magnesium phosphate or other _ fast setting compounds may also be used. The major proportion of particles have approximately the same drop rate in water, so that when poured through water according to the invention, the material does not appreciably segregate. 5

These compositions may further include a filler component of sand or aggregate particles, provided that the major portion of those particles have a drop rate in water which is approximately the same as the cement particles. Also, the cementitious mixture should be able to absorb and/or combine with water in the amount necessary to obtain hydration without mixing. Generally, the amount of water will range between about 20 to 80% by volume, with approximately 50% by volume being contemplated for the preferred formulations at this time. The higher the amount of water the cementitious mixture can tolerate, the better the finished product.

It is possible to use other additives in these compositions. Such additives may include, but are not limited to, accelerators, water reducing compounds, pumping aids, water absorbing compounds, waterproofing agents, polymers, drying shrinkage inhibitors, wet shrinkage inhibitors, lime, pigments and the like, and may be added to improve or impart a particular property to the composition.

The invention also relates to a method for making these compositions. These methods include providing the cement binder in the form of finely divided particles and adjusting the drop rate of the major portion of particles to approximately the same range. Filler components, if added, are treated the same. When fillers are added, it is preferable to mix the dry ingredients to a homogenous consistency. _Q The invention also contemplates various methods for installing cement products upon a substrate which comprises saturating the substrate with an amount of water which is substantially in excess of the normal amount of dry components which are subsequently added. The dry power is g added without mixing in a manner such that it combines with

a portion of the water and displaces the remainder of the water. The applied combination is then allowed to cure to final product. Specific installation methods are further described hereinbelow.

The present invention also relates to a method of mixing dry materials which comprises continuously introducing a fluid medium into a mixing column having an upper and lower end for a time sufficient to allow the fluid to at least substantially fill the column; introducing a predetermined amount of at least one primary material into the upper end of the mixing column; permitting the primary material to descend through the fluid medium at a predetermined rate; introducing at least one secondary material into the mixing column through at least one position along at least one side thereof at an angle and velocity sufficient to cause the secondary material to intimately contact the primary material along its path of descent through the fluid medium so that the primary and secondary materials are continuously mingled as they descend through the fluid medium until they reach the lower end of the mixing column; and recovering the mixed materials from the lower end of the mixing column. One specific application of the present invention relates to a method of manufacturing a cementitious composition which comprises continuously introducing water into a mixing column having an upper and lower end for a time sufficient to allow the water to at least substantially fill the column; introducing a predetermined amount of at least one cement material into the upper end of the mixing column; permitting the cement material to descend through the water at a predetermined rate; introducing at least one secondary material into the mixing column through at least one position along at least one

side thereof at an angle and velocity sufficient to cause the secondary material to intimately contact the cement material along its path of descent through the water so 5 that the cement material and secondary material are continuously mingled as they descend through the water until they reach the lower end of the mixing column; and recovering the mixed cementitious composition from the lower end of the mixing column. Another aspect of the invention relates to a method of making a dry cementitious composition which is capable of setting and curing to a solid mass when poured upon or through excess water. This method includes the steps of providing a cementitious composition in the form of finely 5 divided particles comprising of at least one cement binder and a filler component, and adjusting the drop rate of the particles such that a major proportion thereof possess approximately the same drop rate, so that the composition ' is capable of setting and curing to a solid mass when _Q poured into an amount of water which is present in excess of that needed to completely hydrate the composition without any type of physical mixing of the cementitious composition and water other than that which occurs when the composition is poured into the water. Preferably, g substantially all the particles have approximately the same drop rate and the cement binder is present in the composition in an amount of at least 20 weight percent, although amounts of as low as 10 percent can provide acceptable performance. 0 The drop rate of the primary material, which in one aspect is a cement material, in the fluid medium can be determined prior to introducing it into the mixing column so that the locus of the primary material in the mixing column may be determined at any given time. Also, the rate 5 at which the primary material descends through the fluid

medium can be adjusted by modifying the size, density and/or shape of the primary material to permit it to descend more freely through the fluid medium. ' In addition, the drop speed of the primary material can be changed by dropping the material from an increased height or by utilizing a second fluid to impart an increased velocity to the particles. Also, a surfactant can be added to the fluid media to reduce surface and/or interfacial tension thereby facilitating the dispersal of the primary material through the fluid medium.

Thus, since the method of the present invention does not require an energy supply to provide a thoroughly mixed final cementitious composition of proper integrity, the costs associated with standard mixing methods are dramatically minimized. Furthermore, those problems encountered with respect to the deterioration of machine parts ascribed to wear and tear are substantially eliminated. Other advantages include the elimination of noises associated with standard machine operations, as well as an elimination of any pollution problem, since the present method is performed in a closed circuit.

The method of the present invention is equally applicable to the mixing of non-cementitious materials to form non-cementitious mixtures. Specifically, the method of the present invention can be used to blend or mix a variety of materials to produce food products, medicinal products, resins and other commercially marketed products. Also,the mixed materials form another aspect of this invention.

Brief Description of the Drawings

These and other features of the invention will now be described by way of example with reference to various 5 embodiments of the invention as illustrated in the accompanying drawing, wherein:

FIG. 1 is a perspective view of an apparatus particularly suited for performing the method of the present invention. FIG. 1, when considered along with the description provided herebelow, further provides a schematic representation of the preferred dry blending method of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 5 The invention relates to dry cementitious compositions which are poured, troweled or sprayed through excess water or onto wet surfaces without mixing to hydrate the cement component and obtain high strength products after setting and curing. Cementitious compositions of Portland cements, gypsums, high alumina cements, other specialty cements and combinations, as well as other chemicals such as magnesium phosphates, all have been successfully used, the only limitation being that at least one component of the cementitious composition is hydrated 5 by or reacts with water.

By "cement binder" what is meant is a material, usually of a cementitious nature, which sets or cures upon contact with and hydration by water to form a solid mass which is useful for forming blocks, shapes, structures, _Q walls, floors, or other surfaces for use as a supporting or load bearing member. In addition to the well known cement binders, such as Portland cement, aluminous cement, gypsum and its variations, magnesium phosphate cements and the like, other materials, such as pozzolans, cementitious 5 waste products, or similar compounds which set and cure in

a manner similar to Portland cements, are also contemplated as being within the scope of this term. Other silica bearing materials in the form of finely divided particles 5 having large specific surface areas that are physically sorptive are contemplated as binder components, with representative examples including clays (see Clays, Kirk- Oth er Concise Enclyclopedia of Chemical Technology, John Wiley and Sons, 1985 pp. 283-4) and silicates such as sand

₁₀ and quartzite (see Silicates, The Encyclopedia of

Chemistry, 3rd edition, Litton Educational Publishing, Inc., 1973 pp. 999-1000. Other silicates can also be used. Aluminum silicate is a specific example of a material which is used for specialty applications due to its relatively

₁₅ high cost compared to the other materials previously mentioned. The cement binder may be used alone or with various additives and fillers, usually sand or aggregate, to form the desired member after setting and curing. When the formulations of these cementitious

_ ₀ compositions are properly controlled, the problems of thorough wetting of the cement without overwetting, segregation of components, and loss of compressive strength of the cured product are greatly reduced or eliminated.

Where cement coatings are desired, the surface area

₂ _ to be coated is first prewetted and saturated with water. The dry cementitious mixture is placed on the surface, instantly reacting with the wet surface. If additional layers or a greater thickness of the coating is needed, the first cement layer can be prewetted and the dry

« ₀ compositions sprayed directly thereupon to increase the thickness and structural strength of the overall coating. On horizontal surfaces, the area to be poured with cement is first flooded with water, then the dry cementitious compositions of the invention can be poured

₃₅ into the water. The excess water is displaced by the

cementitious compositions, and the composition is then allowed to cure. This provides a fast, simple installation of cement without the need for tools, mixing apparatus, water measurements aids or the like. For floor levelings, for example, the floor can be flooded to form puddles in low areas. The dry cementitious composition is then sprinkled in the areas which puddles are formed, and allowed to cure. Thus, the floor is easily levelled by this procedure.

Alternatively, the dry cementitious compositions can be pumped or sprayed onto a saturated substrate as described above. This provides the end user with a wide, versatile range of installation methods from which they can choose the most appropriate for a particular application or end use.

The drop rate of the particles of the cementitious compositions is controlled to achieve the desired effect when the particles are poured through water without any other form of mixing. The drop rate of the particles through water is dependent upon several factors of which the density or specific gravity is but one. Although important, balancing the density alone is insufficient to achieve a uniform drop rate sufficient to prevent segregation or dilution of the particles. The size, shape and surface characteristics of each of the particles used, both alone and relative to the other components, must be considered to assess the resistance of the particles dropping through water. For example, round or teardrop shaped particles drop faster through water than coarse, flat or irregular shaped particles, even if each have the same density.

Other variables can be controlled to improve the drop rate. Surfactants can be added to the water separately or along with the dry composition itself to overcome surface

tension and assist in the dispersal of the particles through the water. The distance that the particles must fall through the water is also a consideration, with shorter distances allowing a greater tolerance of differing drop rates. Thus, the dry composition can be introduced by a layering method to achieve the entire desired thickness without having to be dropped a large distance through water. A conduit can be used to direct the dry materials underwater so as to effectively reduce its dropping distance through the water. Dry blending all ingredients to a uniform homogenous composition also assists in achieving a uniform drop rate as well as in an improvement in the consistency and properties of the cured composition. All these factors must be considered and routine tests conducted to obtain a dry cementation system of components having balanced or similar drop rates so that no substantial segregation or substantial dilution of the particles occurs as the composition drops or falls through a quantity of water which is present in excess of that needed to hydrate the cement binder. Dropping the cement binder through the water assures that each cement article is hydrated without depending upon physical mixing.

In addition to the control of the drop rate of the particles, however, certain hydration agents can be included in the dry composition to assist in attaining a properly cured solid mass. By "hydration agent" we mean an additive or compound which enables the dry composition to tolerate the excess water when dropping therethrough. For example, a hydration agent of a water absorbing compound can be added to the composition in an amount sufficient to absorb a portion of the excess water to prevent over-hydration of the cement binder and to prevent dilution or segregation of the particles. Additional cement has been found to be another suitable

absorbing agent. Fine sand can also be used for this purpose. Anhydrous salts, clay, superslurpers, fly ash or other hydrophilic materials may be used under certain conditions. At this time, additional cement or a second cement binder is the least expensive water absorbing agent and for that reason is preferred.

Alternatively, an accelerator can be added to the dry ingredients, as the hydration agent in an amount sufficient to impart relatively fast hydration properties to the cement binder to enable the composition to rapidly set and cure before the excess water can cause over-hydration, dilution or segregation of the composition. The accelerator can be added to the dry mixture or separately into the water. Instead of utilizing a separate accelerator, it is also possible to modify conventional cementitious materials to achieve faster setting compositions.

In this regard, the hydration agent can be heat (used to raise the temperature of the water to increase the setting and curing time of the cement binder when dropping therethrough) or other additives, such as surfactants, which enable the composition to drop through the water more easily. Furthermore, the use of pure or clear water is not required, since the invention is operable in polluted or contaminated water or even seawater, since the method of dropping the cement binder particles through the water, rather than by physical mixing, assures that each particle becomes hydrated properly. ₀ In Portland cement, one or more of the following changes would decrease the setting time of the mix and eliminate the need for the addition of accelerators:

1) increase the tricalcium aluminate (3CaO A1_0_) content to at least about 15% by weight of the g clinker; In doing this, it is advantageous to

reduce the dicalcium silicate (2CaO SiO_) content accordingly. Also, it is suggested to maintain the iron oxide (Fe-O-) content as low as possible 5 to avoid the formation of tetracalcium alumino ferrite (4CaO l ₂ 0 ₃ Fe ₂ 0 ₃ ) .

2) maintain the free lime (CaO) content as low as possible.

3) do not add gypsum (CaSO.) or reduce the amount of 0 gypsum added during the grinding stage. A preferred replacement is a carbonate compound such as sodium carbonate or an alkali metal sulfate other than calcium, such as sodium or magnesium sulfate. It 5 is also possible to obtain advantageous compositions by utilizing a different form of gypsum, such as the hemihydrates, instead of the anhydrous or dihydrate forms presently in use. High alumina cement ("HAC") can also be modified by 0 increasing the percentage of C_ ₂ A_ i.e., 12CaO 7A1 ₂ 0_, present. This will avoid the need for accelerators such as the lithium carbonate which is normally used.

Controlling the rate of hydration leads to many applications. For instance, for coating vertical surfaces, ₅ a very fast setting material can be used to eliminate the problems of running, sagging or failure to bond. Where mortar for bricklaying is desired, a material with a long set time will allow the operator sufficient time to work with the material. For situations where the surface _Q particles have not been properly wetted, additional water may be applied to the surface or upon the dry composition for more activation and further finishing.

In the past, there has always been difficulty in controlling the amount of water for the patching of ₅ highways or other horizontal surfaces. This problem is

solved by this invention because the amount of water is controlled by the formulation of the dry cementitious composition itself. For example, water can be placed into a footing, post hole, mortar joint or tub, or pothole and then the dry cementitious material may be placed by pouring, spraying, or screening into the cavity until the desired level is reached. Excess water, if present, is displaced from the hole by the dry material. The rate of setting of the cementitious mixture can be designed to meet the needs of the particular application. The amount of water required depends on the specific composition and application used. After the hole is filled, a plywood board or similar member can be placed on top to level the upper surface.

For the placement of concrete foundations, a hole is first prepared, then filled with the required amount of water. If desired, forms can be used to help contain the water. The dry material can then be poured directly into the foundation area to the desired height, thus displacing the excess water, if any. After the material cures, the foundation is complete.

It is also possible to control the depth of water through which the dry composition has to drop. This ₅ enables the desired thickness to be built up in steps or layers, with a certain thickness less than the total desired being achieved in each step or layer by dropping the dry composition into the water.

In certain circumstances, a cavity could have a small _Q percentage of water placed into it and then the first part of the cementitious mixture dropped into the water. While this placement is taking place, additional water could then be placed into the hole by various methods simultaneously with the placement of the rest of the cementitious mixture. 5When the final quantity of the cementitious mixture is

reached, the entire surface area could be sprayed for troweling or other finishing purposes as could be done when the entire mixture is poured through water. 5 In the situation where the cavity is porous and cannot hold water, it is possible to thoroughly wet the surfaces of the hole and then introduce a fast setting cementitious mixture. It is then possible to provide excess water in the lined hole and proceed as above. 0 The control of density, shape and size of the dry components and their rate of dropping through water is essential for the proper performance of the cementitious mixtures. The ability to use materials of various sizes and densities, whose drop rate would otherwise be higher if 5 a slow setting cementitious mixture was used, is enhanced by the increased rate of the water activation of the cementitious parties to form a homogeneous mixture.

The use of specific cementitious compositions may be varied or adjusted to meet the needs of the particular 0 application. The most ideal situation is to balance the drop rate for all the dry ingredients and to control the setting time of the cement so that all particles will be properly hydrated and integrated with the aggregates, if any. In this manner, masonry walls can be built up with 5 mortars which are hydrated after installation. Precast and prestressed sections are put in place, the dry mixture is placed in water in the joints and the surface can be wetted down for complete activation of the cement binder. The setting time of the binders can be accelerated to a few _Q seconds or slowed up for days, depending upon the selection of cement component.

The system can be used with any normal additives acceptable to the specific composition. In some compositions, e.g., those based on 100% by weight of one or 5 more cement binders, no separate hydration agent is

required. Furthermore, these compositions may contain numerous chemicals or additives that are compatible to the system for the purpose of improving or imparting certain properties. Additives such as accelerators , water reducers, bonding agents, curing agents, or pumping or waterproofing aids may be added to the compositions of the invention. These additives or modifying agents can be added to the water or to the cement mix, in any order or combination. The amounts or types of such additives may have to be modified from conventional usages taking into account the setting and curing times for the specific composition.

The examples show the success of adding cementitious compositions to water after the water is in place.

When dry, preblended materials are used, there is a much greater potential for higher quality finished product.

If aggregates are found to be too heavy, smaller aggregates or lighter weight aggregates can be used to keep the drop rate of the overall system in balance.

The present invention provides the following:

1. Dry cement can be used.

2. Cement and sand can be used.

3. Cement, sand and aggregates can be used. 4. All types of cements can be used.

5. All types of cementitious particles, such as gypsums, limes and so forth can be used.

6. All types of chemical cements, even with water soluble parts, can be used. 7. No wet mixing or blending equipment is required. 8. No addition of water to mixes is required before placement, avoiding all equipment costs and clean up.

9. When placements under deep water conditions where tremes, elephant trunks or pipes would be required, the material under this formula can be placed dry in the tube and activated by available water at the end of the line, thus keeping all conveyances clear of wet cement.

10. When cement contents are too low in mixtures of submit proper strength development or prevent overadsorption of water, resulting in weak or segregated mixes, more cement may be added, or water absorption material may be added, to prevent excess water from decreasing the quality of the mix.

Present cement mixes with less than 20% of a cementi¬ tious binder should have some additional water absorption agent in the mix to prevent overwatering and segregation. Alternatively, a fast setting cementitious mixture or composition containing an accelerator can be used to allow the cement to set before the excess water causes segregation or dilution thereof. Ideally, cementitious compositions of the mixtures should have the maximum amount of water absorbency possible. The higher the ratio of chemically bonded water to the binder, the better and more versatile a product will be achieved.

Cementitious mixtures containing more than 20% cement may or may not need additional cement or water absorbers, or accelerators, depending on the application.

For purposes of convenience and to convey the details of a preferred embodiment of the dry blending aspect of the invention, this description will relate to a method of mixing or combining cementitious materials to provide a cementitious composition. It is to be clearly understood, however, that other materials may be mixed or combined in accordance with the present invention to provide non- cementit;ious compositions or mixtures.

The primary material used to prepare the cementitious composition in accordance with the method of the present invention can include, but should not be limited to, 5 Portland cement, gypsum, high aluminum cement, other specialty cements, mortar and combinations thereof. The term primary material also includes modified cements, such as those containing about 20 to 30 percent of tricalcium aluminate. (Conventional Portland cement contains about 10 0 to 15 percent tricalcium aluminate.) In these materials, it is advantageous to reduce the iron and calcium oxide content of the composition to as low a value as practical for optimum results.

The primary material can also include other cements 5 which fall under the term "hydraulic cement." This term is Used herein to mean expansive cements, air entraining cements, pozzolanic cements, slag cement, masonry cement, white portland cement, colored cement, antibacterial cement, waterproof cement, blast furnace cement, refractory _Q cement, self-stressing cement and similar materials, in addition to the materials mentioned above.

Also, the term "gypsum" as used herein is intended to include gypsum such as is normally understood in the art. This would include calcium sulfate (CaSO.) and its various ₅ forms such as calcium sulfate anhydrate, calcium sulfate hemihydrate, and calcium sulfate dihydrate, as well as calcined gypsum, pressure calcined gypsum, and plaster of Paris.

Included among the secondary materials are filler ₀ components, such as sand, aggregate particles or mixtures thereof, and a wide variety of additives which may be included to impart certain qualities or characteristics to the final cementitious composition. Such additives can include, but should not be limited to, retarders ₅ accelerators, water reducing compounds, pumping aids, water

absorbing compounds, waterproofing agents, polymers, drying shrinkage inhibitors, wet shrinkage inhibitors, lime, pigments, bonding agents, curing agents and the like. 5 Generally, the mixture should have at least 20 percent of a cementitious binder, although the invention is operable with binders as low as about 10 percent by weight. For instance, a cement mix with less than 20% of a cementitious binder should have some additional water 0 absorption agent in the mix to prevent overwatering and segregation, or an accelerator compound which enables the mix to rapidly cure when hydrated with excess water. Ideally, cementitious compositions of the mixtures should have the maximum amount of water absorbency possible. The higher the ratio of chemically bonded water to the binder, the better and more versatile a product will be achieved.

Referring now to FIG. 1, illustrated is an apparatus for practicing the method of the present invention, which is generally designated by reference numeral 10. The 0 principal component of the apparatus is column 12 which includes ingress means 14 disposed at upper end 16 and egress means 18 disposed at lower end 20. Ingress means 14 is adapted to be sealed by cap 22. Similarly, egress means 18 is adapted to be sealed, as illustrated, by closure 5 member 24, which is pivotably mounted to column 12 by pivot 26 at lower end 20.

Column 12 is illustrated as a cylindrical tube having a tapered lower end 20 of inverted conical shape. To provide a considerable quantity of a final mixed product, _Q column 12 should have a height to diameter ratio of greater than 1:1, preferably greater than about 1.5:1.

A wide range of fluid mediums can be used in this invention. For the preparation of dry mixtures, gases such as air, oxygen, or inert gases such as nitrogen, argon and 5 the like are entirely suitable, as well as mixtures

thereof. When hygroscopic particulate materials are to be mixed, the water or moisture content in the gaseous fluid medium should be maintained at a minimum level. If 5 necessary, the gases can be heated to remove any such moisture prior to introducing the fluid into the column.

Other suitable fluid mediums include liquids, such as water or aqueous solutions, including those of an acidic or basic nature. Also, any organic solvent which is a liquid 0 at the operating temperature and pressure (usually ambient and atmospheric) can be used, including paraffinic, aliphatic or aromatic organic solvents such as hexane, decane, benzene, toluene, gasoline, kerosene, and the like. Halogenated (primarily chlorinated) hydrocarbons, such as 5 ethylene dichloride or carbon tetrachloride, are also suitable. While solvents having any flash point can be used, those having a relatively high flash point and appropriate vapor pressure are preferred in order to minimize the possibility of fire or explosion. When low _Q flash point solvents are used, the proper precautions and safeguards relating to fire or explosion hazards should be followed.

One preferred fluid for purposes of this description is water, is introduced into the hollow interior 28 of ₅ column 12 by way of fluid inlet means 30. The water is introduced into the bottom of the column with egress means 18 being sealed by closure member 24 so that the water fills the bottom of hollow interior 28 and migrates progessively upward in the direction of upper end 16. When _Q the water has risen to a level so that it at least substantially fills hollow interior 28, the primary material, which for purposes of this description is Portland cement, can be introduced into column 12 through ingress means 14. 5

The total amount of each material required to produce a final cementitious composition can be determined prior to commencing the practice of the present invention. The specific amount and the type of each ingredient employed, as well as the inclusion or exclusion of one or more additives to obtain a cementitious blend of desired integrity are well known to the skilled artisan and require no elaboration herein. A predetermined amount of Portland cement is introduced into column 12 through ingress means 14. Once the predetermined amount has been completely introduced into column 12, ingress means 14 is sealed by engagement with closure member 22. As the Portland cement descends through the water disposed in hollow interior 28, the secondary materials can be introduced into column 12 through feed pipes 32a, 32b and 32c, so that they intimately contact and become mingled with the Portland cement along its path of descent. In order to permit any secondary materials to intimately contact the Portland cement along its path of descent, the drop rate of the cement in the water must be determined so that the locus of the cement mass in hollow interior 28 can be determined at any given time. The drop rate of Portland cement, or any other material, through the fluid medium (i.e. water) is dependent upon several factors such as density and specific gravity, as well as the size, shape and surface characteristics of the material. Generally, to determine the drop rate of Portland cement, an amount of the dry cement can be poured into a 3 inch diameter open top plastic or glass cylinder that is about 75% filled with water. The time it takes for the cement to completely descend through the water will provide a suitable indication of what the drop rate of the cement

is in water. Then, the drop rate of the cement in water and the length of the column both being known, one to can easily determine the precise locus of the cement particles within column 12 at any given time.

If desired, the drop rate of the cement can be somewhat adjusted by the practitioners of the present invention. For instance, the size, density and/or shape of the cement can be modified so that the cement particles can descend more freely through the water. In addition, or alternatively, surfactants can be added to the water, either separately or along with the cement itself, to reduce surface and/or interfacial tension, thereby assisting in the dispersal of the particles through the water. Further, desirable additives for modifying or improving the properties of the hydrated cement mixture can be added to the water instead of being introduced as a particulate additive.

The velocity at which the secondary materials are introduced into hollow interior 28, as well as the amount of such materials to be introduced can be regulated by valves 34a, 34b, 34c. The precise and most desirous angle of introducing the secondary materials into hollow interior 28 along the path of descent of the Portland cement so that ₅ the secondary materials intimately contact the Portland cement in order to provide a cementitious composition of desired integrity can be easily ascertained by routine trial and error experimentation.

To discharge the cementitious product from hollow _Q interior 28, closure member 24 is opened so that the product -can flow, by gravity, into a suitable receptacle (not shown) so that it can be carted or otherwise transported or directed to a work site.

5

It is readily apparent to one skilled in the art that the present methods provide substantial advantages in its simplicity of construction, which avoids the use of 5 internal structure components, such as baffles, trays and the like. Furthermore, the avoidance of agitators, impellers and other mixing equipment enables the user to obtain a highly significant reduction in operating costs due to the lower energy input and maintenance rquire ents

10 of this invention.

As stated above, the method of the present invention can be used to mix or blend non-cementitious materials to produce non-cementitious mixtures. For instance, a variety of organic or inorganic powders can be blended in

15 accordance with the instant method to produce a variety of commercial products, such as food products and medical products. In these instances, the fluid can be an inert gas as opposed to the water specifically used for the present description. The present method can also be used

20 to manufacture organic resins.

The materials of construction for the tower when most particulate compounds are to be mixed can be carbon steel, but other materials can be used for particular applications. For example, stainless steel, or plastic in

„ the form of lined or coated steel or as an integral vessel, can be used where high product purity is required, whereas refractory ceramic, tile, or rubber linings can be used for highly abrasive powders.

While it is preferred that the primary and secondary

2 _Q materials be substantially non-reactive with each other, as well as with the fluid medium, it is also possible to react the primary and secondary materials with each other, or with thei fluid medium, to achieve a desired product.

5

Also contemplated is the situation where the fluid medium contains a component which is capable of combining with the primary and secondary materials to form a desired product. As an example, an accelerator can be added to the water for the mixing of cementitious materials therewith, so that a relatively fast setting composition can be achieved.

Examples

The scope of the invention is further described in connection with the following examples which are set for the sole purpose of illustrating the preferred embodiments of the invention and which are not to be construed as limiting the scope of the invention.

In the examples that follow, the components of each cementitious composition were manufactured of finely divided particles having substantially the same drop rate in water, so that the advantages previously discussed could be achieved _*

The first 9 of the following examples are cementitious materials that were poured into a 4" x 8" cylinder which was half filled with water. The material was poured until it reached a level near the top of the cylinder (i.e., from about 1/2" below to slightly above) . The mixture was leveled to assure that no air pockets were present in the cylinder, additional water was added if dry powder remained at the top, and the cementitious composition was then allowed to cure.

Example l. (Comparative)

Substance (common sand/cement mix) Percentage

Portland Cement Type I 20% Sand 80%

Set time is 20 hours.

Compressive strength at 24 hours is 0.0 psi (too little cement and no absorbing or acclerating agent)

Example 2.

Substance Percentage

Portland Cement Type I 90% Sand 10%

Set time 12 hours.

Compressive strength at 24 hours is 1,100 psi.

Example 3.

Substance Percentage

Portland Cement Type I 50%

Sand 50% Set time 16 hours.

Compressive strength at 24 hours is 600 psi.

Example 4. (Comparative)

Substance Percentage

Portland Cement Type I 50%

Pea Gravel 50%

Set time 16 hours. Compressive strength at 24 hours is 0.0 psi. (different drop rates) .

Example 5.

Substance Percentage

_ Portland Cement Type II 50%

5

Plaster of Paris 50%

Set time is 10 minutes. Compressive strength at 24 hours is 1,600 psi. 0

Example 6.

Substance Percentage

High Alumina Cement 80%

Sand 20% 5

Set time is 12 hours.

Compressive strength at 24 hours is 1,100 psi.

Example 7. (Comparative) 0

Substance Percentage

High Alumina Cement 20%

Sand 80%

Set time is 20 hours. 5

Compressive strength at 24 hours is 0.0 psi. (too little cement and no absorbing or acclerating agent) .

Example 8.

Substance Percentage 0

High Alumina Cement 25%

Portland Cement Type III 25%

Lithium Carbonate 1%

Sand 49% 5

Set time is 5 minutes.

Compressive strength at 24 hours is 1,100 psi.

Example 9.

Substance Percentage

₅ Magnesium Oxide 30%

Ammonium Phosphate 10%

Sand 60%

Set time is 5 minutes.

10 Compressive strength at 24 hours is 1,100 psi.

To illustrate the difference in properties of the final hydrated composition based on the use of various size test specimens, the following Table B is provided. Four different size test specimens of two different compositions ' ⁵ were tested for compressive strength at one and seven days. In each case, the test specimens were formed by pouring the dry composition into the containers which were each 40% filled with water.

TABLE B

20

Composition Age 2"X1"X2" 3" dia. 4" dia (days) Rect. 2"Cube X6" cyl. x8" cy

20% Portland 1 850 psi 580 psi 0 psi 0 psi

(White Type III) 1 7 3000 psi 1480 psi 650 psi 570 ps

25 80% Sand #1

20% Secar 51 1 3650 psi 3200 psi 1080 psi 760 ps

80% Sand #1 7 4950 psi 3500 psi 1300 psi 1100 p

³⁰ *Secar 51 is a High Aluminum Cement.

The above results indicate that the composition will yiel higher compressive strengths as the size of the test speciment decreases. 35

The following examples were based upon the preparation of cubes from a cube mold which was half filled with water and to which the dry cementitious components were added in the same manner as above.

Examples 10-15

The following formulations were prepared. All proportion are given in weight percent unless otherwise noted.

Example

Components 10 11 12 13 14

Portland cement Type I 90 90 90 - - sodium carbonate 5 5 10 10 10 potassium chloride 5 - - - — magnesium formate - 5 - - - gypsum free Portland cement - - - 90 50 sand - - - - 40

These formulations were tested for set time and early strength with results shown in Table B below.

TABLE B

Initial Final 1 Day 3 Day 7 Day

Set Set Strength Strength Strength

Example (min.) (min.) (psi) (psi) (psi)

10 3 76 1,250 - -

11 - 15 250 — —

12 5 14 775 - 1,300

13 4 6 - 2,200 -

14 7 9 — 1,925 —

These examples illustrate that various accelerators can be added to the dry cement mix prior to dropping the mix into the water.

Example 15

In this example, a dry composition of 19.7% aluminous cement, 40% Portland cement, 40% sand and 0.3% lithium carbon ate was prepared and preblended. This formulation was droppe into water at various temperatures to determine the effect th temperature of the water has on the final set time of the mix. Results are as follows:

Water Temperature (°F) Final Set (Min.)

70 (tap) 8

110 (tap) 5

180 (tap) 3

32 (salt) 19 45 (salt) 15

62 (salt) 14

80 (salt) 10

108 (salt) 6

These examples illustrate the use of heat as a set or cure accelerator. Also, the invention is operable with salt o polluted water instead of fresh tap (i.e., potable) water.

Examples 16-20 100% Portland cement Type I was poured into water containing a saturated solution of the following accelerators:

Example Accelerator(s)

16 50:50 mix sodium formate/sodium carbonate

17 calcium chloride

18 potassium fluoride

19 calcium formate 20 sodium carbonate

Results on set time and early strength are shown in Table C.

TABLE C

Initial Final 1 Day 3 Day 7 Day

Set Set Strength Strength Strength

Example (min.) (min.) (psi) (psi) (psi)

16 - - 700 2,350 2,625

17 120 - - ^' - -

18 10 - - - -

19 10 13 250 - -

20 60 6 700 1,650 2,175

This illustrates that solid accelerator compounds can b added to the water rather than to the dry cement mixture.

Example 21

A formulation of neat Portland cement of particles havi the same drop rate was poured into a 90% water/10% triethanolamine mixture. The triethanolamine acts as an accelerator so that the following properties were obtained.

INITIAL FINAL EARLY 1 DAY

SET SET STRENGTH STRENGTH 3 minutes 8 minutes 2 hours 275 PSI

100 PSI

This example illustrates the ability of the invention t be operable with a liquid accelerator added to the water rath than to the dry cement.

Example 22

The following example illustrates the modification of a high alumina cement to achieve the desired results of the invention.

Substance FORMULA A FORMULA

Portland Cement Type I 40% 40%

"0" Sand 40% 40%

Conventional High Alumina Cement 20%

Modified High Alumina Cement with increased C ₁₂ A_ 20%

Final Set time 8 minutes 3 minute

1 Hour Compressive Strength Time zero 250 PSI

This example illustrates the ability of the invention t be operable with a liquid accelerator added to the water rath than to the dry cement.

Examples 23-30

The following examples were based upon the preparation two-inch cubes from a cube mold half filled with water and to which the dry cementitious compositions were added in the same manner as in Examples 1-9.

Example 23

Substance Percentage

Portland Cement Type I 16% P40 Sand 84%

One Day Strength = 75 psi

Example 24

Substance Percentage

Portland Cement Type I 16%

P40 Sand 83%

*JM Micro-Cel 1%

One Day Strength = 150 psi

Example 25

Substance Percentage Portland Cement Type I 16%

P40 Sand 74%

Montour's Fly Ash 10%

One Day Strength = 250 psi Example 26

Substance Percentage

Portland Cement Type I 16%

P40 Sand 73%

*JM Micro-Cel 1% Montour's Fly Ash 10%

One Day Strength = 325 psi Example 27

Substance Percentage Portland Cement Type I 15%

P40 Sand 85%

One Day Strength = 50 psi

Example 28

Substance Percentage

Portland Cement Type I 15%

P40 Sand 84%

*JM Micro-Cel 1% One Day Strength = 75 psi

Example 29

Substance Percentage Portland Cement Type I 15%

P40 Sand 75%

Montour's Fly Ash 10%

One Day Strength = 175 psi Example 30

Substance Percentage

Portland Cement Type I 15%

P40 Sand 74% *JM Micro-Cel 1%

Montour's Fly Ash 10%

One Day Strength = 50 psi

*JM Micro-Cel is a Johns-Manville product. It is a synthetic calcium silicate with an extraordinarily high liquid absorpti capacity because of its very high surface area. However, it not a hydraulic cement.

While it is apparent that the invention herein disclose is well calculated to fulfill the objects above stated, it wil be appreciated that numerous modifications may be devised by those skilled in the art, and it is intended that the appended claims cover all such modifications and embodiments as fall within the true spirit and scope of the present invention.