BONDED AGGREGATE STRUCTURES AND PRODUCTION THEREOF

Abstract: Bonded aggregate structures, processes for their production, improved wall, floor and ceiling panel structures laminated with bonded aggregates and methods for their production are provided. The structures are made using a workable quick setting non-toxic non-ammoniacal mixture of magnesium oxide, silicate, aggregate and mono aluminium phosphate acidic solution. The panel structures, especially for building purposes and the like, can be made in various forms ranging from low density to load-bearing forms which may be refractory, insulative, heat reflective (12, 13), light weight, labor and energy conserving, etc.

Description: -.- Description Bonded Aggregate Structures and Production Thereof Cross-Reference To Related Applications This application is a continuation-in-part of U.S. application Serial No. 325,393, filed November 27, 1981. Technical Field This invention relates generally to bonded aggregate structures and their production and to improved building (wall, floor and ceiling) panel structures and the like laminated with bonded aggregate and methods for their production. Background Art Bonded aggregate structures are well known for refractory purposes (e.g., 3,285,758) and for outdoor load-bearing and road repair use (e.g., 4,059,455). The mixtures used for forming the known structures require a high content of ammonium phosphate components. Such use is impractical and even hazardous for many purposes, particularly indoors or at building sites where good ventilation is unavailable to remove the high concentration of gaseous ammonia generated by the bonding reaction. It is therefore an object of the present invention to provide bonded aggregate structures and means for their production which avoid the disadvantages of the prior art structures and processes. It is also an object of the invention to provide bonded aggregate structures in any of a variety of densities, compress iv it ies, shapes, reflectivities, insulative and energy transfer qualities, fire resistant properties and the like. It is another object of the invention to provide economical means for improving the energy efficiency of panel structures and the like as, for example, in furnaces, stoves, heaters, radiant heat panels, wall, floor and ceiling surfaces, building and room dividers, warehouse and storage spaces, heating and processing zones and the like. It is still another object to provide means for the fast repair, retrofitting and/or construction of insulative or load-bearing surfaces, structures and the like, advantageously at ambient temperature. These and other objects, features and advantages will be seen from the following detailed description of the invention. Disclosure of The Invention The invention in one aspect is in bonded aggregate structures obtained at ambient temperature by establishing a workable aggregate mixture which undergoes an exothermic reaction, working the mixture into a predetermined form prior to setting, and allowing the worked form to set into a rigid structure. The workable mixtures of the invention are constituted with magnesium oxide, silicate, aggregate and aluminum phosphate acidic solution; optionally with compatible structural fibers such as glass fibers and filaments. While the quality and proportions of the components are not particularly critical, the weight ratio of silicate (a typical silicate being mullite) to acidic solution (expressed as 50% solution with a weight ratio P2°5 S A -**-2 < ** , 3 °*^ aDOU,t 4 ) suitably is from about 3:2 to about 4:1, the weight ratio of magnesium oxide to (silicate (i.e., mullite) is from about 1:7 to about 1:10, and the quantity of acidic solution relative to the total mixture is sufficient prior to setting to impart lubricity (that is, smoothness and uniformity) to the mixture. The setting time of the mixture can be varied as desired. By increasing the relative proportion of silicate the setting time is increased. A workable mixture of the invention, consti¬ tuted with magnesium oxide, silicate (such as silicate sand or aluminum silicate), light weight aggregates such as vermiculite, per lite or glass beads and aqueous mono aluminum phosphate acidic solution, may be combined to form a light weight, low density material used for insulating purposes. In this mixture, the weight ratio of magnesium oxide to the mono aluminum phosphate acidic solution is approximately 3:1. By increasing the magnesium oxide content to as high as 20%, an almost instantaneous setting time can be achieved. This light weight mixture may be expanded for insulating purposes by adding a carbonate to the mixture. Various carbonates such as dolomite, magnesium carbonate, caffeine carbonate and sodium carbonate may be used at a weight ratio of carbonate to magnesium oxide from 3:1 to 4:1. By adding as much as 40 to 60% of the carbonate material to the mixture, an expansion of up to ten times the original volume of the mixture can be achieved, thereby reducing the weight of the end product to as low as 7 to 10 pounds per square foot. In order to achieve a closed cell product, either aluminum salt of commercial stearic acid or zinc salt of commercial stearic acid (commonly referred to as aluminum stearate and zinc stearate, respectively) may be added to the above mixture. The weight ratio of the aluminum stearate or zinc stearate to magnesium oxide under these circumstances is approximately 1:99. The magnesium oxide used is a dry dead-burned particulate magnesia. A typical chemical analysis and mesh size for magnesia may be the following: Standard Oxide Mesh Size Si0 2 4.6% +48 0.2% Fe 2°3 2.7 +100 6.5 A1 2 0 3 1.2 +200 21.6 CaO 4.2 +325 17.7 MgO 87.3 -325 54.0 (Bulk density, g./cc, 3.16) The aggregate is any suitable siliceous aggregate or mixture of such aggregates having an average density ranging from light to heavy depending on the intended use. The size range of the aggregate is not critical and suitably may be from under 1/16 inch to OMH over 1/2 inch. Examples of aggregate materials are cellular and non-cellular materials such as sand, stone, refractory aggregates, silica aggregates and rare earth materials, peagravel, expanded per lite and vermiculite, 5 volcanic glass, volcanic ash, pumice, glass beads and the like. In applications where high mass is a problem, the use of cellular, low density aggregate is preferred, the density for strength and low weight advantage preferably being in the range from about 5 to about 15 10 pounds per cubic foot. Glass beads, perlite and vermiculite are preferred cellular low density aggregates. For high density bonded aggregate structures, an aggregate such as stone, refractory aggregate, sand or gravel is preferred. - j e The aqueous mono aluminum phosphate acidic solution can be varied in concentration and amount used such that it is equivalent for purposes of imparting lubricity to an aluminum phosphate, 50% solution, technical grade, having the following typical 20 properties: Formula: Al (H 2 P0 ) 3# XH 2 0(in aqueous sol.) Molecular Weight: 318 for AL (H 2 P0 ) 3 Description: A clear, water-white solution Typical Analysis: P2°5 : 33.5% 25 A1 2°3 : 8*0% P 2 0 5 /A1 2 0 3 : 4.19 A1 2°3/ p 2°5 s °- 24 ALP0 : 19.0% Physical Properties:pH (1%) solution): 2.1 Specific Gravity: 1.47 @ 25/15.5°C Bau e: 46 @ 25°C 35 Viscosity: 35-90 centipoise Loss at 110°C: 48-50% Miscibility w/water Total Silicate is a dry sandy powder found naturally or synthetically produced. Although any silicate may be used in this mixture, metallic silicates such as aluminum silicate or magnesium silicate are employed for applications requiring some heat reflectivity. One commonly used silicate, an aluminum silicate known as mullite, has the following typical analysis: Formula: 3Al 2 0 3 -2Si0 2 Alumina 60.31% Silica 38.73 Iron Oxide .50 Titania .67 Lime .03 Magnesia .01 Alkalies .42 A variety of carbonate compounds may be used to expand the light weight material in the mixture of the second embodiment. One carbonate commonly used, dolomite, has the following typical analysis: Formul a : CaMg ( CO3 ) 2 Calcium Carbonate (CaC0 3 ) 54.4% Magnesium Carbonate (MgC03) 44.5 Silicon Dioxide (Si0 2 ) 0.50 Aluminum Oxide (Al θ3) 0.35 Iron Oxide (Fe 2 θ3) 0.10 Moisture 0.15 Stearic acid, the final ingredient which may be added to the light weight mixture to produce a closed cell product is typically of the form of zinc stearate or aluminum stearate having respectively the following analyses : ZINC STEARATE FORMULA: Zn (C 18 H 35 0 ) 2 DESCRIPTION: Zinc Salt of Commercial Stearic Acid APPEARANCE: Slightly Off-white, Free- flowing Powder TYPICAL PROPERTIES: % Ash 15.0 % Water Soluble Salts NIL % Free Fatty Acid 0.5 % Moisture 0.4 Mean Melting Point 120 Degrees C OMPI Apparent Density 0.3 gm/cc Fineness 98% passing 200 mesh ALUMINUM STEARATE FORMULA: AL (OH) C 18 H 35 0 2 ) 2 DESCRIPTION: Aluminum Salt of Commercial Stearic Acid APPEARANCE: Free Flowing, White Powder TYPICAL PROPERTIES: % Ash 10.0 % Free Fatty Acid 4.2 % Moisture 0.3 Mean Melting Point 155 Degrees C Apparent Density 0.2 gm/cc Fineness 98% passing 200 mesh An advantage of the instant mixtures is that they can be established under cold weather conditions. No external heat is required. The reaction which takes place upon mixing the components is exothermic. The setting time varies depending on the relative quantities of the components. For example, the setting time of the mixture is about 4 to 6 minutes when the weight ratio MgO: aluminum s i l icate is 9 : 1 and can be extended correspondingly as this ratio is decreased. The setting time of the light weight material of the second mixture may be reduced to an a lmost instantaneous s et by increasing the content of magnesium oxide to as high as 20%. Prior to mixing, the dry and wet components are kept separately. For purposes of mixing, the components are then brought together in any suitable way to provide a uniform workable mixture. Conveniently for this purpose, the dry components of the mixture, magnes ium oxide, s i l icate and aggre¬ gate, can be formulated in a single package or lot separate from the acidic solution. The latter, con¬ tained in an appropriate quantity as a single unit package or lot, can then be combined with the dry components at the site of mixing and forming. The resulting mixture, while still workable is then placed, shaped, compacted, etc., by conventional means, into a OMPI suitable form or cast, and allowed to set until rigid, for purposes of repair, retrofitting or construction. The form used can be a cavity or break in a road surface or bridge, a specially made construction form, a building template or modular form, an open space within a wall or floor or ceiling, the wall surfaces of a chimney or furnace, a panel adapted to receive a covering laminate or layer of settable material, or other similar form. In the preferred method embodiment, a con¬ ventional mixing spray gun is used to apply the compo¬ nents of the mixture to the supporting structure. When a light weight product is desired, the various components of the mixture may be applied with as little as fifteen pounds of pressure using the spray gun. The mono aluminum phosphate acidic solution is kept in a separate chamber in the spray gun and is not combined with the other ingredients until each of the other ingredients and the mono aluminum phosphate acidic solution are simultaneously emitted from the tip of the spray gun. Thus, the use of the mixing spray gun allows for easy, controlled application of the quick drying mixture since the mixture does not begin to set until it is sprayed toward the surface of the supporting structure. For mixtures which employ heavier aggregate, such as stone, the spray gun must be used at a pressure of up to 150 pounds. It will be appreciated by those skilled in the art that the use of the spray gun greatly increases the efficiency of application, particularly in the case of a lightwieght mixture which may set up almost instantaneously. An important advantage of the instant bonded aggregate structures is that they are non-ammoniacal so that during mixing, forming and setting no special precautions need be taken to vent the area of ammonia fumes. Other advantages in this regard are that the formulations are temperature insensitive, can be made to have high early strength, and given the benefit of the present teaching, can be adjusted within wide limits to suit the particular requirements of each job. Thus, the formulation can be varied for setting to a fast or slow rock-hard set by varying the content of silicate or magnesium oxide; for low density (less than about 15 pounds per cubic foot) or high density (more than about 15 pounds per cubic foot), and for various degrees of wetness, looseness, plasticity, stickiness, adhesion, etc., as desired, without special knowledge, by those skilled in the art. For example, by a procedure described below in greater detail, a good high density, load bearing ceramic material having early high strength can be made with the following components: Percent By Weight Magnesium oxide 7-10 Silicate (mixture of, sand and 60-65 aluminum silicate; Mono aluminum phosphate, 50% acidic Solution 25-33 The silicate mixture composition is varied depending on the function to be served. For road repair, or other purposes not requiring a heat reflective surface, little or no silicate other than sand is required. If a heat reflective surface is desired, higher contents of an additional silicate such as aluminum silicate is used. One preferre aspect of the invention is a method of improving the energy efficiency of a room panel or zone-confining panel having a facing surface and an energy-transmissive backing surface. The terms room panel and zone-confining panel as used herein are meant to include wall, floor or ceiling members of buildings? work-station panels, dividers, carrels, stalls, booths, etc.; radiant heat panels, fire walls and false ceilings, panel and wall members of stationary objects such as hoods, stoves, furnaces, vats, boilers, animal shelters, brooders, silos, storage tanks, processing chambers; and the like. The method of improving the energy efficiency of such panels includes the steps of laminating the backing surface, and allowing the thus laminated mixture or cover to set REA. until hard and thereby become rigidly attached to the backing surface. Energy efficiency is realized in that panels laminated according to the invention become heat- insulative, especially panels that are laminated with mixtures containing cellular aggregates such as glass beads, expanded perlite, etc. In the latter case, the K-factor of the resulting bonded aggregate cover is comparable to that of the cellular aggregates per se. When the cover includes a mix of cellular and non- cellular aggregate, certain advantages are seen such as enhanced heat content or capacity whereby the cover has a so-called flywheel effect with respect to retention of heat or energy level over prolonged periods, which serves to avoid precipitious changes in temperature within the confines of the covered panel or panel enclosure. Advantageously, the cover also serves as an acoustical insulator. It will be realized that the cover for the panel can be varied in its coverage of the panel and its thickness. Thus, the cover will ordinarily be completely co-extensive with the panel. The cover can be uniform or non-uniform in thickness, as desired. To assist in strengthening the attachment of the laminate to cover, conventional anchoring means can be used such as lathing strips, fingers, tie rods, perforations, and the like, spaced at intervals on the panel. A preferred panel embodiment of the invention is an overhead or ceiling panel member and preferably a radiant heat panel, laminated according to the method of the invention. A preferred method embodiment comprises the step of anchoring the laminated mixture to the radiant heat panel by spray-gun application of the various components of the desired mixture directly onto the surface of the panel. Referring to the accompanying drawing of a preferred radiant heat panel or space heater panel, according to the invention. Figure 1 is a view showing the facing surface; and Figure 2 is a cross-sectional view of the panel taken on line 2-2 of Figure 1 showing the panel O PI and its cover of laminated bonded aggregate structure . As seen in Figures 1 and 2, the radiant heat panel 10 has an exposed surface 11 and a congruent backing surface 12 to the latter of which a bonded 5 aggregate 13 is attached. The attachment is favored and prevented from latera l dis lodgement by mold forming relief means or sunk relief anchor means 14. A support system 20, suspended from overhead as from the ceil ing (not shown) of a building or room by a cable or chain 21 0 attached to the panel is used to maintain the panel 10 steady at a predetermined position above the floor for purposes of heating the space within the room. Further cable segments 22 support a reflector 23 which in turn by attachment to cable segments 24 and mounting base 24a 5 support a gas burner 25 and pilot 26. The latter burner and pilot unit is serviced by a temperature control ler 30, gas supp ly l ine 31, and burner and pi lot lines 32 and 33. In a preferred embodiment, the panel 10 is 23 gauge steel, 4 feet in diameter with one foot center-to- 0 center radial sacing of the circumferential anchor means 14. The bonded aggregate cover 13 is about 1-2 inches thick. The heating unit uses a burner rated at 15, 000 BTU. Air temperature control is adj ustable from 78 to 110 degrees F. 5 In a preferred procedure, the backing surface 12 of the panel is laminated to a depth of about 1 to 2 inches us ing a uni form mixture of the fo l lowing components : Percent By Weight n Magnesium oxide υ . .BBRRII,, ddrryy bbuurrrn.e_d_ .M_A_GNES„IT_E DB87,, aavvaaiillaabbllee rrrrppiijjii BBaassiicc RReeffrraaccttoorriieess „ ,„ Cleveland, Ohio) 7-10 Mixture of Silicate and 5 Glass beads,, cellular,, „ . „ (size distribution, l/lfi" to 1/2", . ^n _ available from Norton Chemical Co.) 60-65 Mono,Aluminum Phosphate. 50% aqueous 0 solution, (available from Stauffer Chemical Co., Westport, Conn.) 25-33 Here, again, the composition of the mixture of silicate and glass beads is varied depending on the -^lREAl OMPI desired rate of setting and strength. Silicate typically comprises 10-40% of the silicate-glass mixture. The dry ingredients are first mixed and placed into one chamber of a conventional mixing spray gun. A small amount of clay (less than about 5% by weight is preferably added to the dry ingredients to provide lubricity. The mono aluminum phosphate acidic solution is placed into a second chamber in the gun. The mono aluminum phosphate acidic solution then combines with the dry ingredients as each of these components is emitted from the tip of the spray gun during application. By varying the amount of magnesium oxide, the setting time can be varied from nearly instantaneous (within one minute) to eight minutes. The laminated panel can be used immediately for radiating heat. Surprisingly, the savings in energy usage typically is 20 to 50% or more. The increased efficiency is seen by the fact that heat losses are minimized such that to maintain a given temperature, the burner unit is activated substantially less frequencly than with prior art uncoated heater panels. It should be noted that delaying the mixture of the dry ingredients with the mono aluminum phosphate acidic solution until they are actually emitted from the tip of the mixing spray gun allows for easy control and application of a mixture since the mixture does not begin to set until it is actually being sprayed onto the surface of the supporting structure. The lamination according to the invention can be advantageously done using a conventional panel 10 which lacks the relief shaped anchor means 14. Optionally, the facing surface 11 of the cover 13 can be coated with a suitable light or heat reflective paint or similar coating. The radiant heat panels of the inven- tion are preferred for animal shelters, especially for brooder radiant heat panels used, for example, in raising chicks. The embodiments of the invention in which an exclusive property or privilege is claimed are defined

Claims: as follows. CLAIMS 1. A bonded aggregate structure obtained by establishing a non-ammoniacal workable mixture by weight 5 of 7-10% magnesium oxide, 60-65% silicate and aggregate, and 25-33% aqueous mono aluminum oxide solution, the quantity of acidic solution relative to the total mixture being sufficient prior to setting to impart lubricity to the mixture; working the mixture 10 into a predetermined form, and allowing the thus worked form to set into a rigid structure. 2. A structure according to Claim 1 where the aggregate is cellular and has a low density in the range from about 5 to about 15 pounds per cubic foot. •^5 3. A structure according to Claim 2 where the aggregate comprises glass beads. 4. A structure according to Claim 2 where the aggregate comprises perlite. 5. A structure according to Claim 2 where the 20 aggregate comprises vermiculite. 6. A structure according to Claim 1 where the aggregate comprises a stone or refractory aggregate. 7. A structure according to Claim 2 further expanded in volume by adding a carbonate to the mixture 5 to the extent that 40-60 percent by weight of the mixture is carbonate. 8. A structure according to Claim 7 wherein the carbonate material is dolomite. 9. A structure according to Claim 2 wherein 0 aluminum stearate is added to the mixture at a ratio of aluminum stearate to magnesium oxide of 1:99 in order to OMPI form a closed cell structure. 10. A structure according to Claim 2 wherein zinc stearate is added to the mixture at a ratio of zinc stearate to magnesium oxide of 1:99 in order to form a 5 closed cell structure. 11. A structure according to Claim 1 wherein the silicate component is mullite. 12. A bonded aggregate structure obtained by establishing a non-ammoniacal workable mixture of 10 magnesium oxide, aluminum silicate, aggregate, and aqueous mono aluminum oxide solution, the weight ratio of silicate (using aluminum silicate as a typical silicate) to acidic solution (expressed as 50% solution with P2O5: I2O3 of about 4) being from about 3:2 to 15 about 4:1, the weight ratio of magnesium oxide to aluminum silicate being from about 1:7 to about 1:10, and the quantity of acidic solution relative to the total mixture being sufficient prior to setting to impart lubricity to the mixture; working the mixture 20 into a predetermined form, and allowing the thus worked form to set into a rigid structure. 13. A structure according to Claim 2 made from a mixture containing by approximate weight 8% magnesium oxide, 25% aluminum silicate, 35% aggregate and 32% 25 acidic solution. 14. A structure according to Claim 13 where the aggregate comprises glass beads. 15. A process for producing a bonded aggregate structure comprising the steps of establishing '30 a workable non-ammoniacal mixture by weight of 7-10% magnesium oxide, 60-65% silicate and aggregate, and 25- 33% aqueous mono aluminum phosphate acidic solution, the quantity of acidic solution relative to the total mix¬ ture being sufficient prior to setting to impart OMPI lubricity to the mixture; working the mixture into a predetermined form; and allowing the thus worked form to set into a rigid structure. 16. A process for producing a bonded aggregate structure comprising the steps of: (a) establishing a mixture of magnesium oxide, silicate, aggregate and clay; (b) placing said mixture into a chamber of conventional mixing spray gun; (c) placing an appropriate amount of mono aluminum phosphate acidic solution in a separate chamber of the mixing spray gun, the percentage by weight of the components being 7-10% magnesium oxide, 60-65% silicate, aggregate and clay, and 25-33% acidic solution, the quantity of clay relative to the mixture being sufficient prior to setting to impart lubricity to the mixture; and (d) spraying each of the components onto a supporting structure, whereby, the mixture and the mono aluminum phosphate solution are emitted from the tip of the spray gun, the mixture combines with the mono aluminum phosphate acidic solution and begin to set into a rigid form. 17. A process according to Claim 15 where the * aggregate is cellular and has a low density in the range from about 5 to about 15 pounds per cubic foot. 18. -process according to Claim 17 where the aggregate comprises glass beads. 19. A process according to Claim 17 where the aggregate comprises perlite. 20. A process according to Claim 17 where the aggregate comprises vermiculite. - OREAi O PI 21. A process according to Claim 17 where the aggregate comprises a stone or refractory aggregate. 22. A process according to Claim 17 made from a mixture containing by approximate weight 8% magnesium 5 oxide, 25% aluminum silicate, 35% aggregate and 32% acidic solution. 23. A method of improving the energy efficiency of a room panel or zone-confining panel having a facing surface and an energy-transmissive 0 backing surface, which comprises the steps of laminating the backing surface with a workable mixture according to Claim 1 to provide a generally co-extensive energy conserving cover for the backing surface, and allowing the thus laminated mixture to set until hard and thereby become rigidly attached to the backing surface. 24. A method according to Claim 23 where the panel is a floor or wall member. 25. A method according to Claim 23 where the panel is an overhead or ceiling member. 26. A method according to Claim 23 where the panel is a radiant heat panel. 27. A method according to Claim 23 where the panel is a brooder radiant heat panel. 28. A method according to Claim 23 which comprises the step of anchoring the mixture to the panel by pre-formed mold defining relief surface means in the panel. 29. A method according to Claim 28 which comprises the step of removing the relief surface means * subsequent to the setting of the laminated mixture such that portions of the underside of the laminated mixture are exposed. 30. A radiant heat panel produced by the method of Claim 26. 31. A brooder radiant heat panel produced by the method of Claim 27. 32. A brooder radiant heat panel produced by the method of Claim 28. 33. A brooder radiant heat panel produced by the method of Claim 29. O PI

Inventors: SHUBOW CALVIN, SHUBOW, CALVIN
Applicants: SHUBOW CALVIN, SHUBOW, CALVIN
Application year: 1984
Main classification: C04B9
IPC codes: C04B28, C04B35, F24C1