Disclosure of Invention
Typical mixture embodiments for combining with water to make a slurry that hydrates to form a high strength flooring composite include: from about 50% to about 98% by weight calcium sulfate hemihydrate, from about 0.002% to about 1% by weight polysaccharide, and from about 0.02% to about 2.5% by weight lignosulfonate (lignosulfate).
Detailed Description
Before discussing exemplary embodiments of the invention in detail, some embodiments of the invention should be understood to be directed to a mixture for use with water to prepare a slurry that hydrates to form a high strength flooring composite. Other embodiments are directed to methods of making a subfloor, and still other embodiments are directed to a subfloor. Furthermore, in describing particular embodiments of the present invention, it is to be understood that the description may have additional related embodiments. For example, when describing the mixture of the present invention, one skilled in the art will understand that the description also applies to the method of preparing the mixture.
In the exemplary embodiments detailed below, it should also be understood that all ingredients in the composition are referred to as dry ingredients in the dry mixture. It is contemplated that this is only one possible embodiment, and that the liquid component is equivalent to the dry component when the assay is performed on a dry solid basis. Unless otherwise indicated, all ingredients are determined on a dry solids weight basis, excluding any aggregates or fillers that may be present.
A typical mixture for making a slurry suitable for use in flooring applications is made from the following ingredients: about 50% to about 98% calcium sulfate hemihydrate, about 0.002% to about 1 wt.% polysaccharide, and about 0.02% to about 2.5 wt.% lignin. It has been found that the combination of polysaccharide and lignin, an example of which is lignosulfonate, can produce surprising and beneficial results with respect to increased strength, better flowability, reduced exudation, increased sand concentration, and other physical properties of the resulting slurry. Importantly, this exemplary embodiment achieves these benefits without the use of so-called superplasticizers. Thus, cost savings are realized.
The main component of the dry mixture is calcium sulfate hemihydrate. The dry mixture composition may include from about 50% to about 98 wt.% hemihydrate. Other possible ranges of calcium sulfate hemihydrate include from about 80% to about 98%, from about 80% to about 95%, or from about 88% to about 95% of the dry mixture.
Any type of hemihydrate can be used in such a mixture. Can be prepared by any known method, such as slurry (slurry), lump (lump) or air calcination. Alpha-calcined calcium sulfate hemihydrate or beta-calcined calcium sulfate hemihydrate can be used in the mixture. The alpha form of the calcium sulfate hemihydrate crystals has less acicular shape than the beta form. The less needle-like shape allows for better wetting and flow of the crystals when mixed with water. The lower water demand of the alpha form can produce denser and higher density composites than the interlocking matrix of calcium sulfate hemihydrate crystals produced using the beta form of calcium sulfate hemihydrate. As is known in the art, the combination of alpha and/or beta calcium sulfate hemihydrate can control the amount of water required to form a workable slurry, which can control the density of the final model.
Any alpha or beta calcined hemihydrate can be used in the present compositions. Preferred alpha hemihydrate compounds include those produced by a slurry process, such as the HYDROCAL C-Base, J-Base or E-Base produced by the United States Gypsum Company (Chicago, IL), produced by a stone process, such as the HYDROCAL A-Base or B-Base, or any other process for producing alpha calcined hemihydrate. Molding gypsum No. 1 is preferably beta hemihydrate produced by United States gypsumo (Chicago, IL). Continuous calcination of synthetic gypsum is equivalent to beta-calcined hemihydrate. Beta hemihydrate prepared by other methods may also be used. The addition of soluble calcium sulfate anhydrite can suitably replace up to 50% of the hemihydrate and can provide strength to the matrix. Calcium sulfate dihydrate is used as a filler and can only be used in small amounts, less than 25 wt.% of the hemihydrate.
Whether beta calcined gypsum, alpha calcined gypsum, or a combination of alpha and beta is selected for a particular application depends on a number of factors. For example, beta calcined gypsum can be used in large part when cost is a major concern. Beta calcined gypsum also has higher workability, and lower exudation than the alpha form. However, in some embodiments, alpha hemihydrate, or a mixture of the alpha and beta forms, is preferred if even higher strengths are desired. When a mixture of alpha and beta calcined hemihydrate is used, the mixture should include at least 25% beta-hemihydrate. In some embodiments, the amount of the β -calcined form is greater than 50% or greater than 90% of the total hemihydrate.
Surprising and unexpected results that appear in some examples of this embodiment of the invention include high finished floor strength resulting from processing a mixture of gypsum in the alpha hemihydrate form using only the stone process. The strength rating achieved is generally believed to be due to the use of more expensive slurried alpha hemihydrate mixtures. The exact chemistry behind this unexpected result is not known with certainty, which is believed to be related to the synergistic reaction between polysaccharide and lignosulfonate.
It has further been found that polysaccharides in combination with lignosulfonates unexpectedly promote sand loading (sand loading) resulting in lower water demand, provide good lift performance to the slurry, reduce bleed and settling, promote pumpability and flow properties, and improve strength of the finished product. These benefits can be achieved regardless of whether or not specific calcium hemihydrate is used.
The effect achieved cannot be reproduced by using equal (or greater) amounts of either component alone. Furthermore, while the particular chemical mechanism that contributes to these unexpected effects is not fully understood, it is believed that this is related to the synergistic combination of these two components.
The polysaccharide serves to maintain the components of the slurry in suspension until the crystalline matrix is sufficiently formed to ensure uniform distribution. Preventing the precipitation of sand or other aggregates. The slurry has a low viscosity and is easy to pump, thus reducing energy consumption. The workability and surface smoothness of the composition are also increased.
The polysaccharide ranges from about 0.002% to about 1.0% by weight. Other possible polysaccharide weight ranges include from about 0.01% to about 0.5%, from about 0.02% to about 0.25%. Many different polysaccharides can be used in different example mixtures. Some typical polysaccharides particularly suitable for use in the present invention include biopolymer gums (biopolylactic gums) and dextran products (e.g., scleroglucan, schizophyllan, etc.). Scleroglucan is produced by filamentous fungi of the genus Sclerotium. Schizophyllan is an exopolysaccharide produced by fungi of the genus Schnizophyllum.
Scleroglucan and schizophyllan are polysaccharides whose linear chains of 1-3 linked D-glycosyl units have from about 30% to about 35% of the linear chains containing a single D-glycosyl unit linked by 1-6 linkages. Average molecular weight of 5X 10 or more6. They are nonionic homopolysaccharides (homopolysacchrides). The chains are self-connected into a triple helix arrangement. They dissolve in water to form a pseudoplastic solution. Other characteristics of these compounds and their preparation are disclosed in U.S. patent No. 4,954,440, which is incorporated herein by reference. One commercially available example of scleroglucan is sold under the trade name BIOVIS by SKW Polymers (Kennesaw, GA). Other polysaccharide gums, such as xanthan gum, welan gum, and others, may also be used in the present invention.
Other typical polysaccharides include heteropolysaccharides. These polysaccharides are high molecular weight, usually linear carbohydrate polymers containing two or more different mono-polysaccharides. The two or more mono-polysaccharides form polymeric repeat units, such as S-657 discussed in U.S. patent nos. 5,175,278 and 6,110,271, which are incorporated herein by reference. This polysaccharide is an example of a xanthan gum particularly suitable for use in the present invention. S-657 forms an elongated, coiled, triple-folded, levorotatory, double helix (extended intetwanned 3-fold left-folded double helix), with a molecular weight estimated to exceed two million daltons, which is available from Kelco Biopolymers (San Diego, Calif.) under the trade name Diutan (or Diutan Gum).
Typical embodiments of the present invention further comprise about 0.02% to about 2.5% lignin or similar plasticizers. Other ranges include from about 0.025% to about 1.25%, and from about 0.025% to about 0.625%. One lignin that is considered particularly useful is lignosulfonate. Lignosulfonates or sulfonated lignins (CAS number 8062-15-5) are water-soluble anionic polyelectrolyte polymers that are byproducts of the wood pulp production process using sulfite pulping. They help prevent the other ingredients of the mixture from agglomerating, thereby increasing the fluidity of the mixture. In typical embodiments of the present invention, it has further been found that there is a synergistic unexpected interaction between them and the polysaccharide, resulting in the unexpected benefits and advantages noted above. One typical Lignin suitable for use in embodiments of the present invention is the Marasperse C-21 product, which is available from Reed Lignin, Greenwich, Connecticut.
Typical formulations of the invention may include other ingredients such as defoamers, retarders, accelerators, and the like. Various additives may be used depending on the particular application, process conditions, and other considerations.
Many other additives are suitable for optimizing the dry mix. An antifoaming agent may be used to reduce air bubbles generated during mixing of the dry mixture with water. When used, the dry mixture contains up to 0.5% defoamer. FOAMASTER CN (Astro Chemicals, Kankakee, IL) is a typical defoamer. Boric acid may optionally be added to the dry mixture to reduce calcination and mold/mildew growth (mold/milew). Typically, it is added in an amount of up to 1.25%. Other suitable ranges for boric acid addition are up to 1% and up to 0.5%.
Retarders are added to increase the working time of the slurry. The target working time, for example, from about 10 minutes to about 2 hours, can vary depending on the composition used and the location and manner of application of the slurry. Any retarder known to be useful with calcium sulfate hemihydrate can be used in amounts to produce a working time consistent with the target range. Typical are protein retarders such as SUMA, tartaric (potassium hydrogen tartrate), sodium citrate and diethylenetriaminepentaacetic acid.
A set accelerator is used to promote the setting of the slurry. Any known accelerator that promotes the setting of hemihydrate may be used including, but not limited to, sulfates, acids, and calcium sulfate dihydrate. The amount used may vary depending on the potency of the selected accelerator, but is typically less than 1 wt.%.
Finely ground calcium sulfate dihydrate is a typical accelerator. When freshly prepared, it has high performance and is suitable for immediate use in a slurry. However, it loses its effectiveness when stored for a period of time before use. U.S. patent No. 2,078,198, which is incorporated herein by reference, discloses improved accelerators which contain calcium sulfate dihydrate mixed with a material such as sugar. This mixture makes the calcium sulphate dihydrate less susceptible to ageing deterioration and it is suitable for use in the slurry within a few days (weeks). U.S. patent No. 3,573,947, which is incorporated herein by reference, discloses heating a co-ground sugar and calcium sulfate dihydrate mixture to cause the molten sugar to form a film on the calcium sulfate dihydrate. The molten sugar film further stabilizes the calcium sulfate dihydrate, which may reduce the aging effect to a greater extent than an unheated sugar/dihydrate mixture. Ground calcium sulfate dihydrate prepared according to this method is referred to in the examples as "CSA" (United states gypsum co., Chicago, IL). Regardless of the form, the milled dihydrate is typically used at a concentration of less than 0.5 wt.%.
The compositions of the present invention optionally have a number of other additives depending on the particular application. These additives may include thickeners, colorants, preservatives and other additives present in amounts known in the art. The skilled person is aware of additives for specific purposes, as well as appropriate concentrations. Colorants, such as pigments, dyes or tints, may also be used as additives, especially in flooring applications. Any known colorant may be used in the present invention. Titanium dioxide is particularly suitable for use in whitening compositions. The colorants are used in the amounts and addition methods normally used in compositions of this type. Other additives will be apparent to those skilled in the art.
Other embodiments of the invention include slurries made by combining sand and water with the mixture of the invention. Such a slurry can be used to form high strength flooring and the like. Mixing is usually carried out on site. The amount of water added to the dry mix varies depending on the application. Reducing the water content saves time and energy because less water needs to be removed by drying. However, sufficient water must be provided to ensure proper fluidity, mixing and reaction of the dry ingredients.
For best control of the properties of the slurry and set gypsum, the water used to prepare the slurry should be as pure as the water actually used. Salts and organic compounds are known to regulate the set time of the slurry and they range widely from accelerators to set inhibitors. Some impurities can cause structural errors, reducing the strength of the solidified product due to the formation of a matrix in the crystalline form of the dihydrate. Thus, the use of non-polluting water as is practically used can improve the strength and consistency of the product.
The properties of the final slurry, such as flowability, bleed, settling, etc., are important for the application field. If the slurry does not flow well, for example, high labor costs, uneven final flooring, and/or other undesirable results can occur. Similarly, excessive flow can result in uneven final floor quality, lower finished strength, and the like. Embodiments of the present invention were found to provide excellent final slurry properties.
A particular advantage of some embodiments of the invention is the discovery that the synergistic effect of polysaccharides and lignin can significantly support higher sand suspensions than the prior art. Good sand suspensions (based on typical commercial packaging including 80lb of dry mix and industry standards for the ease of end users of sand content in cubic feet) are obtained using a sand ratio of 0.8: 1 to 2.3: 1 in embodiments of the invention (expressed in units of cubic feet of sand per 80lb of dry mix sample). Using the present invention, it is believed that the sand ratio can be extended to 2.5: 1 or higher, and even 3: 1 or higher.
Various embodiments of the present invention include the use of formulations having a sand ratio of about 1.9: 1 to 3.5: 1, about 1.9: 1 to 2.3: 1, about 1.9: 1 to 3: 1, at least about 2.3: 1, at least about 2.5: 1, at least about 3.1: 1, and at least about 3.5: 1. Some of these ratios, particularly those of higher sand content, combined into good physical properties of the article, were previously unknown and showed surprising and advantageous results. Although the specific reasons for this achievement are not clearly known, it is believed that this is caused at least in part by a synergistic interaction between the components of the formulation, including the polysaccharides and lignosulfonates.
It is also noteworthy that the strength of the final floor structure increases with increasing alpha hemihydrate usage, and the surface hardness is unexpectedly hard. These end product properties are unexpected. Initially, more expensive plasticizers were used for these properties, an example being PCE. Achieving these end product qualities is again believed to be caused at least in part by the synergistic interaction between the polysaccharide (and especially possibly diutan gum) and the lignosulfonate, does not require a higher cost PCE, and presents more valuable and important advantages over the prior art.
Detailed Description
To further illustrate these embodiments of the present invention, example formulation ranges are provided.
TABLE 1
In Table 1 above, HYDROCALB-Base is an alpha hemihydrate made from a stone process under controlled pressure and temperature. HYDROCALC-Base is alpha hemihydrate made from a slurry process under controlled pressure and temperature and with the addition of a crystallization modifier in the process. Two hydrate products are commercially available from United States glyphosate corp. The molded article is a salt treated (aridized) kettle gypsum or a beta hemihydrate base made from gypsum in an atmospheric environment. Other alpha or beta hemihydrate forms of gypsum are also contemplated as being useful in the present invention.
Foamaster CN is a brand defoamer available from Geo Specialty Chemical, in LaFayette, Indiana. It is a petroleum-based defoamer. Other classes of defoamers that may be used include, but are not limited to, silicate-based defoamers such as AGITAN brand defoamers available from Applied Chemicals International Group, Basel Switzerland, HI-MAR defoamers available from Hi-Mar Specialty Chemicals, Milwaukee, Wisconsin, Colloid brand defoamers available from Rhone-Poulenc Chemicals, France, and Spa type defoamers in liquid form (added at the work site) or in powder form (provided in a dry mix). Marasperse C-21 is a lignosulfonate-type plasticizer produced by ReedLignin, Greenwich Connecticut. The Suma retarder is a protein or amino acid based retarder, commonly used in the formulation of gypsum-based products. Such retarders may be used alone or in combination with other known types of retarders such as, but not limited to, Rochelle salt, ammonium tartrate, sodium citrate, citric acid, and soda retarders.
CSA is a weather stable accelerator produced by u.s.gypsum Company, Chicago Illinois. It is a gypsum-based accelerator. HRA or heat resistant accelerator and anhydrite are two examples of other acceptable gypsum-based accelerators. Potassium sulfate, aluminum sulfate, and zinc sulfate are also useful accelerators for the purposes of the present invention to control set time, improve surface hardness, aid in the completion of surface hydration, and potentially reduce the swelling of hardened flooring.
The "C" cement is classified as an oil well type cement, and the C3A content is low, which also satisfies the classification of type 5 cement. Such cements can be used to reduce the risk of potentially producing destructive ettringite when there is an excess of water-based and gypsum-based materials. Other useful types of cement include type I, type II and type III, fly ash and other types of fly ash cement.
Diutan gum is used in the above examples and is believed to provide particular efficacy in various embodiments of the invention, but other polysaccharides are also useful. They include, but are not limited to: gum types such as welan gum, xanthan gum, and others listed above are also useful. Combinations of stabilizers are also useful. WALOCEL methylhydroxyether cellulose from Wolff Cellulosics, Willowbrook, Illinois may also be used, or methylcellulose ethers may also be used.
To better illustrate some of the advantages achieved and the unexpected results by the embodiments shown in table 1, sand and water were added to these mixtures to form the slurries of the present invention. These slurries are then allowed to set and dry to form the solids of the present invention, such as a sub-floor or floor structure. The sand used for the test was Mohawk fine sand.
At the location of laying the floor or subfloor, water is measured in the desired ratio of the desired components based on dry solids and placed into a mixing vessel. If any wet or liquid component is used, it is mixed with water. The dry ingredients were then mixed into water to form a homogeneous slurry. The slurry is then applied, pumped, poured or poured onto a substrate and allowed to set, forming a floor or subfloor.
It is generally advantageous to vary the composition within the scope of the invention depending on the mixing or pumping equipment used. Different brands of pumping equipment generate shear forces that require certain characteristics of the slurry to flow properly. Some machines use aggregates of a particular size distribution. Other machine manufacturers suggest slight variations in the composition. Modifying the composition to accommodate equipment is within the ability of those skilled in the art to frequently prepare slurries on such equipment.
Although the flooring product does not require finishing, it is desirable to perform the finishing under conditions well known to those skilled in the art. The conditioning technique is selected so that the conditioner controls the surface characteristics to some degree, including surface wear. The floor is optionally finished using any technique known to cement finishers including, but not limited to, floating, pin-rolling, troweling.
Table 2 summarizes the results of the inventive slurry and the floor construction examples.
| Example 1 | Example 2 | Example 3 |
| Test 4000g batches based on sand and working formula | | | |
| Every 4000gWater for use | 40-270cc | 135-250cc | 165-225cc |
| Collapse (inch) | 5-12 inches | 7-11 inches | 8-10 inches |
| Wet Density (lb/ft)3) | 120-145 | 125-140 | 130-135 |
| Dry density | 100-130 | 105-125 | 110-120 |
| Compressive strength | | | |
| Example 1 | Example 2 | Example 3 |
| Wet strength after setting for 2 hours | 300-4000psi | 500-3000psi | 600-2500psi |
| Dry strength after 8 days in the dryer | 1000-9000psi | 1200-6000psi | 1500-5000psi |
| Water seepage: (%) | 0-1％ | 0-.5％ | 0％ |
| Sand suspension recording: | 15-120min | 30-100min | 35-60min |
| reference: | | | |
| sand: working formula ratio | 0.5: 1 to 3.1: 1 cubic foot of sand per 80lb of working formula | 0.8: 1 to 2.7: 1 cubic foot of sand per 80lb of working formula | Every 80lb of working formula is 1.2: 1 to 2.5: 1 cubic feet of sand |
| Mohawk Fine test Sand Density (lb/ft) of Sand3) | 95 | 95 | 95 |
| Surface velocity: | 2-7 | 5-7 | 6-7 |
TABLE 2
A short description of the testing and physical property procedures is provided to more fully illustrate the data of table 2 (this discussion is also useful for similar data provided by the other tables below).
Slump tests are used to describe the suspension of aggregates such as sand in a slurry. This test was used to simulate the situation of floor dumping and slurry pumping through a hose. Occasionally it is necessary to stop pumping in order to switch to a different batch or move to a different section of the floor. During this time, the slurry quietly set in the hose for several minutes before pumping resumes. Collapse tests were used to simulate these conditions.
Weigh and dry blend all dry ingredients (including aggregates) together. A predetermined amount of deionized water was measured out and poured into the mixing bowl. The dry mix was added to water and the time point recorded as the starting point to determine the set time. The mixing bowl was placed in a Hobart mixer with gentle bumping for about five minutes. After one minute of soaking, the material was stirred at low speed for two minutes. The bowl was removed from the mixer and the contents were mixed with wisker (wisk) for 15 seconds to ensure uniform mixing of all materials.
The initial collapse test specimen was poured into a moist 2 "x 4" (5cm x 10cm) cylinder placed on a plastic sheet, slightly filling the cylinder. The excess material was smoothed from the top and the cylinder was then lifted smoothly so that the slurry flowed out of the bottom, forming a cake. The patties (± 1/8 ") were measured 90 ° apart in both directions and the average was recorded as the patty diameter. The remaining sample material was allowed to set quietly in the pitcher for 5 minutes. Additional collapsed samples were poured at five minute intervals without stirring until all the material was poured or until the material was set and could not be poured. The mixture between collapsed samples was not stirred.
After the material solidified, the water exuded was measured as excess water on the surface of the sample. The 130ml sample was poured into a 240ml coagulation cup and allowed to coagulate until Vicat (Vicat) coagulation was reached. The cup containing the sample and the seeped water was weighed to (+ -0.10 g). The oozing water was then allowed to drain and the cup was shaken to remove excess water. The cup and sample were re-weighed. The water seepage was calculated as follows: (initial weight-final weight) ÷ initial weight 100 ═ water exuded.
The density and compressive strength were tested using two inch cubes packed together. The cubic molds are prepared by sealing the bottom of the mold with petroleum jelly to prevent leakage and lubricating the mold with an approved release agent such as WD-40. The sample material was poured into the cube corner until it was approximately 3/4 full, and stirred if necessary to keep the sand in suspension. The sample material was stirred vigorously from each corner with a small spatula for 3-5 seconds to remove air bubbles from the cube.
The cube was then filled slightly and the remaining sample material was poured into a coagulation cup for further testing. After vicat set for 10 minutes, excess sample was wiped off the cube mold, and after about 50 minutes, the cube was carefully removed from the mold. Cube preparation was about 24 hoursThereafter, it was placed in a forced-air oven at 110 ℃ F. (43 ℃ C.) for 8 days until a constant weight was reached. The density of the sample was determined by weighing a number of dry cubes and applying it to the following formula: density (lb/ft)3) (weight of cube 0.47598) ÷ number of cubes.
The compression strength was tested with the aggregated cubes by using a compression strength tester. The cube was placed between two platens. The platens are pushed together, applying a force to the cube. The machine records pounds of force required to crush the cube. By dividing by the surface area of the sample (in this case 4 in)2) The total force in pounds is converted to pounds per square foot (psi).
The vicat set time was determined by the time the material was added to the water until the 300g vicat needle in the paper cup sample passed 1/4 "to 1/2" of the material.
The water used varies due to the moisture that may be present in the sand. Wet sand requires less water and vice versa. The range of water used for the test was recorded above as 4000g of mixture with 40g of working water and the range was extremely based on wet sand. When the sequence is paramount to the use of the formulation, in this case, sand may be added to the mixture prior to stucco.
Another set of example formulations was prepared with a particularly useful component formulation. It is summarized in table 3:
these formulations are mixed with sand and water for forming the floor structure. The slurry and the final floor structure were tested. The results are summarized in table 4 below:
| test 4000g batches based on sand and working formula | C-BASE/mold examples | C-BASE example | B-BASE example |
| Every 4000g of water used | 205cc | 180cc | 175cc |
| Sand for use | 1262g | 1067g | 1262g |
| Working formula weight g | 2738g | 2933g | 2738g |
| Vicat coagulation (minutes) | 57 | 177 | 240 |
| Collapse (foot) | 8.88 | 8.88 | 9.13 |
| Wet Density (#/ft3) | 130 | 132 | 135 |
| Dry Density (#/ft3) | 115 | 120 | 125 |
| Compressive strength | | | |
| Wet strength after setting for 2 hours | 1267 | 908 | 1917 |
| Dry strength after 8 days in the dryer | 2875 | 2433 | 4392 |
| Water seepage: (%) | 0 | 0 | 0 |
| Sand suspension recording： | Good taste | Good taste | Good taste |
| Test 4000g batches based on sand and working formula | C-BASE/mold examples | C-BASE example | B-BASE example |
| Sand: working formula ratio | 1.9∶1 | 2.3∶1 | 1.9∶1 |
| Recording: | good surface hardness | Good surface hardness | Good surface hardness |
| Surface velocity: | 6 | 7 | 7 |
the above physical properties and experimental data show surprising and unexpected results. Among other things, the strength and surface quality of the sand suspension of the slurry of the present invention and the resulting solid floor structure of the present invention prepared using the formulation of the examples of the present invention, which includes a high concentration of beta hemihydrate ("mold examples," alpha to beta hemihydrate ratio of about 17: 7), showed surprising results. Other surprising results include high strength of solid products prepared using the inventive example formulation, which includes 100% rock alpha hemihydrate. The strength of the material is surprising compared to the strength of the solids made from 100% slurry alpha hemihydrate. Other embodiments of the invention are believed to achieve similar results, with at least about 90% by weight of the gypsum containing rock hemihydrate. Other surprising results include achieving high sand suspension ratios.
These unexpected results are believed to be caused, at least in large part, by the synergy between the polysaccharide and the lignosulfonate in the inventive mixture. These unexpected results also demonstrate that embodiments of the present invention can be used to achieve advantageous physical properties without the cost associated with superplasticizers such as PCE.
The embodiments and examples shown herein are intended to illustrate the invention and are not intended to limit the invention in any way. Any of the embodiments of the present invention may combine optional components of the composition in any useful manner. Other embodiments and uses of the invention will be apparent to those skilled in the art.