Polymeric sand composition having increased resilience

Abstract

A polymeric sand composition is provided, including a blend of sand and an admixture. The admixture includes a dispersible polymer powder and an inorganic mineral binder. The dispersible polymer ponder may include a vinyl acetate ethylene (VAE) copolymer with a vinyl acetate content of at least 50% by weight. The admixture contains polymer powder and inorganic mineral binder in a weight ratio of 40 / 60 to 90 / 10, respectively. The admixture is added to the polymeric sand composition in an amount of 2 to 20% by weight.

Description

[0001] POLYMERIC SAND COMPOSITION HAVING INCREASED RESILIENCE

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a polymeric sand composition for filling joints in construction related applications. More specifically, the invention relates to filling joints such as those between pavers and / or stones with a durable and hard, yet pliable filling composition.

[0004] DESCRIPTION OF RELATED ART

[0005] In the field of civil engineering, there is a need for continuous maintenance of materials used to fill the spaces between paver blocks or stones typically used in such applications as walkways, driveways, or patios. Typically, the spaces separating the pavers' vertical contact walls may be filled with sand. The sand acts as a shock absorbing material when the pavers are subjected to lateral forces applied by rolling vehicles as they pass across its surface. It also prevents the pavers from coming loose from their abutment.

[0006] One common problem with the use of sand as a joint filler, is that being very fine in mesh and light in weight, the sand is prone to erosion out of the interstitial spaces of the pavers by the action of wind, water runoff, rain and general settling due to random load changes on the pavers in their day-to-day use. Due to the loose nature of the material, sand is also susceptible to undesired plant growth in the interstitial spaces of the pavers.

[0007] The use of a polymeric sand in place of plain sand may mitigate the aforementioned problems.

[0008] In a polymeric sand, a graded sand is mixed with a polymeric material. Alternatively, a polymeric material may be applied as a coating to sand grains. The polymeric sand is then transported and installed in various construction applications, such as a road, path, driveway, patio, or other paved application. In such an application, pavers or stones may be installed on a base including aggregate rocks, gravel, and / or sand. After the pavers or stones have been positioned, polymeric sand is swept into the interstitial spaces of the pavers to fix the position of the pavers. The polymeric sand is misted or sprayed with water to activate polymer materials in the sand, which increases adhesion between sand particles and locks the position of the sand. The wetting process may also induce crosslinking of the polymer which further increases the holding the adhesion and holding capability of the sand. The installed polymeric sand provides substantial improvements in resilience and pliability of the sand-filled joints.

[0009] Existing polymeric sand compositions use a high molecular weight polyvinyl alcohol with an optional crosslinker. Commonly used crosslinkers include various boron-based salts and acids. U.S. Patent Publication No. 2010 / 0144944 discloses a polymeric sand composition that remains hard yet pliable over time, comprising polyvinyl alcohol, a borate salt, and a particulate filler.

[0010] However, boron-based compounds have come under regulatory scrutiny over potential negative effects on reproductive health. Accordingly, an objective of the present invention is to provide a polymeric sand composition with a high resilience and pliability without the use of boron-based compounds as crosslinkers.

[0011] Further, crosslinking requires a high molecular weight polyvinyl alcohol, which is expensive and requires specialized equipment to incorporate into a polymeric sand composition. Accordingly, an additional objective of the present invention is to provide a polymeric sand composition without the use of polyvinyl alcohol as a binder and without the use of any high molecular weight polyvinyl alcohol.

[0012] BRIEF SUMMARY OF THE INVENTION

[0013] A polymeric sand composition is provided including a sand, a dispersible polymer powder, and an inorganic mineral binder. The polymeric sand composition includes 0.4 to 8 wt% of the dispersible polymer powder and 0.2 to 4 wt% of the inorganic mineral binder, based on a total weight of the polymeric sand composition. In some embodiments, the polymer powder may be a copolymer of vinyl acetate and ethylene.

[0014] The dispersible polymer powder may also include optional comonomers or fillers, including organic and inorganic fillers. The dispersible polymer powder may also be selected to have a glass transition temperature within a certain range to give polymeric sand composition a desired resilience and pliability.

[0015] In some embodiments, the inorganic mineral binder may be a calcium aluminate cement. The calcium aluminate cement is selected to have an AI2O3concentration and a CaO concentration within a certain range to provide adhesion and improve the overall properties of the polymeric sand composition.

[0016] In other embodiments, oil is added to the polymeric sand composition to suppress dust particles.

[0017] BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0018] The above, as well as other advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description when considered in the light of the accompanying drawings in which:

[0019] FIG. 1 is a photograph illustrating a scratch test result corresponding to Example 3 of the present invention;

[0020] FIG. 2 is a photograph illustrating a scratch test result corresponding to Example 4 of the present invention;

[0021] FIG. 3 is a photograph illustrating a scratch test result corresponding to Comparative Example 1 ;

[0022] FIG. 4 is a photograph illustrating a scratch test result corresponding to Comparative Example 2; DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, the present invention will be described in detail. However, it should be understood that the present invention is not limited to the following embodiments, and that various elements may be variously modified or selectively mixed according to need. Accordingly, it is to be understood that the invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention.

[0024] In addition, throughout this specification, when an element is referred to as "including" an element, it is understood that it may include other elements as well, not meaning excluding other elements unless specifically stated otherwise. The terms "about", "substantially", and the like used in the present specification are to be understood, when manufacturing and material tolerances inherent in the meanings mentioned are presented, as they mean "the numerical value" or "in close proximity to the numerical value", and not in a limiting sense.

[0025] Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

[0026] A polymeric sand composition is provided. The polymeric sand composition comprises sand, a dispersible polymer powder, and an inorganic mineral binder. In a preferred embodiment, the dispersible polymer powder and the inorganic mineral binder are thoroughly mixed to form an admixture. The dispersible polymer powder is disposed in the admixture in an amount of 40 to 90 wt%, preferably 45 to 85 wt%, more preferably 50 to 80 wt%, most preferably 55 to 75 wt%. The inorganic mineral binder is disposed in the admixture in an amount of 10 to 60 wt%, preferably 20 to 50 wt%, most preferably 25 to 45 wt%. The resulting admixture is mixed into the sand to form a polymeric sand composition. The admixture is preferably disposed in the polymeric sand composition in an amount of 2 to 20 wt%, more preferably 3 to 18 wt%, most preferably 4 to 15 wt%. Increasing the amount of admixture in the polymeric sand composition improves adhesion and resilience, while an insufficient concentration of admixture will increase the set time of the polymeric sand composition and may prevent setting altogether. However, it is desirable to limit the concentration of admixture while maintaining good physical properties, as admixture is substantially more expensive than sand.

[0027] In another embodiment, the constituents of the polymeric sand composition may be mixed in a single step, without producing an admixture, provided that the final polymeric sand composition is within the same range as when using an admixture. However, the use of an admixture can improve transportation and storage efficiency, as the admixture can be premixed and added to the sand closer to the final destination.

[0028] The dispersible polymer powders are generally prepared in an aqueous medium and preferably by the emulsion or suspension polymerization process, as described, for example, in WO 2010 / 057888 A1. The polymers in that case are obtained in the form of aqueous dispersions. Such aqueous dispersions are dried to obtain dispersible polymer powders.

[0029] The aqueous dispersion of polymers or copolymers may be formed batchwise using a batch operation, semibatch operation, or a continuous operation. Preferably, the aqueous dispersion is formed utilizing one or more reactors. In some embodiments, a high-pressure reactor followed by a low-pressure reactor in series are utilized. In some embodiments, the aqueous dispersion is formed in a reactor under a pressure of 5-120 bar abs., preferably 10-80 bar abs. The polymerization temperature is generally 20-120°C, preferably 60-95°C.

[0030] Suitable vinyl ester monomers for use in forming the aqueous mixture are carboxylic acids having 1 to 12 C atoms. Preferred vinyl esters are vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, 1-methylvinyl acetate, vinyl pivalate, and vinyl esters of a- branched monocarboxylic acids having 9 to 11 C atoms, as for example VeoVa9® or VeoValO®. Particularly preferred is vinyl acetate. The stated vinyl esters are polymerized in general in an amount of 30-100% by weight, preferably 70-100% by weight, based in each case on the total weight of the monomers.

[0031] When utilized, ethylene is copolymerized with the vinyl ester monomers, in general, in an amount of 1-30% by weight, preferably 10-30% by weight, based in each case on the total weight of the monomers.

[0032] In a preferred embodiment, the polymer is a copolymer of vinyl acetate (VA) and ethylene. The copolymer of VA and ethylene is referred to as “VAE copolymer” hereinafter. In further embodiments, the VAE copolymer may optionally include additional comonomers.

[0033] The VAE copolymer may be any VAE copolymer that includes VA monomers and ethylene monomers that are known in the art without limitation, and in which a VA content is more than 50 wt% with respect to the total weight of the copolymer. In general, the VAE copolymer has a VA content of more than 50% by weight, preferably > 52% by weight, more preferably > 55% by weight, most preferably > 60% by weight, and an ethylene content of less than 50% by weight, preferably 1 to 40% by weight, and optionally further monomers copolymerizable therewith, in each case based on the total weight of the monomer mixture.

[0034] According to an exemplary embodiment, the VAE copolymer has a VA content of more than 50 weight percent (wt%) by weight and 99 wt% by weight or less; and an ethylene content of 1 wt% by weight or more and less than 50 wt% by weight based on the total weight of the monomer mixture.

[0035] Suitable optional comonomers for use in forming the VAE copolymer include the esters of acrylic acid or methacrylic acid, vinyl halides, such as vinyl chloride, and olefins such as propylene. Suitable methacrylic esters or acrylic esters are esters that have unbranched or branched alcohols having 1 to 15 C atoms such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, norbornyl acrylate. Preference is given to methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate n-butyl methacrylate, hexyl acrylate, and 2- ethylhexyl acrylate. When used, these comonomers are copolymerized in an amount of up to 20% by weight, preferably 2% to 20% by weight, based in each case on the total weight of the monomers.

[0036] Optionally it is possible, for 0.05% to 10% by weight, based on the total weight of the monomers, to copolymerize auxiliary monomers. Examples of auxiliary monomers are ethylenically unsaturated monocarboxylic and dicarboxylic acids, preferably acrylic acid, methacrylic acid, fumaric acid, and maleic acid; ethylenically unsaturated carboxamides and carbonitriles, preferably acrylamide and acrylonitrile; monoesters and diesters of fumaric acid or maleic acid such as, for example, the diethyl and diisopropyl esters, and also maleic anhydride, ethylenically unsaturated sulfonic acids and / or salts thereof, preferably vinylsulfonic acid, 2-acylamido-2- methylpropanesulfonic acid. Further examples are precrosslinking comonomers such as polyethylenically unsaturated comonomers, examples being divinyl adipate, diallyl maleate, allyl methacrylate or triallyl cyanurate, or postcrosslinking comonomers, examples being acrylamidoglycolic acid (AGA), methyl-acrylamidoglycolic acid methyl ester (MAGME), N- methylolacrylamide (NMA), N-methylolmethacrylamide (NMMA), N-methylolallylcarbamate, alkyl ethers such as the isobutoxy ether or esters of N-methylolacrylamide, of N- methylolmethacrylamide, and of N-methylolallylcarbamate. In some embodiments, the auxiliary monomers are monomers with hydroxyl or carboxyl groups, such as, for example, hydroxyalkyl esters of methacrylic acid and of acrylic acid, such as hydroxyethyl, hydroxypropyl or hydroxybutyl acrylate or methacrylate, and also 1 ,3-dicarbonyl compounds such as acetoacetoxyethyl acrylate, acetoacetoxypropyl methacrylate, acetoacetoxyethyl methacrylate, acetoacetoxybutyl methacrylate, 2,3-di(acetoacetoxy)propyl methacrylate, and allyl acetoacetate.

[0037] Suitable auxiliary monomers are also ethylenically unsaturated compounds containing epoxide groups, such as, for example, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and vinyl glycidyl ether. Additional suitable auxiliary monomers include silicon functional comonomer. Silicon functional comonomers known in the art to be copolymerized with vinyl esters may be utilized. Examples of such silicon functional comonomers include ethylenically unsaturated, hydrolyzable silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, 3- methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane.

[0038] Preferably, forming the VAE copolymer includes forming a comonomer mixture. Preferred comonomer mixtures are those which contain vinyl acetate and ethylene, more preferably those containing 70-99% by weight of vinyl acetate and 1-30% by weight of ethylene; and also comonomer mixtures which contain 50-90% by weight of vinyl acetate and 1-30% by weight of ethylene, more preferably 10-30% by weight of ethylene, and preferably 1-20% by weight of one or more further comonomers from the group of the vinyl esters having 1 to 12 C atoms in the carboxylic acid radical, such as vinyl propionate, vinyl laurate, vinyl esters of alpha-branched carboxylic acids having 9 to 11 C atoms such as VeoVa9, VeoValO, VeoVal 1 ; and comonomer mixtures of vinyl acetate with 1-40% by weight of ethylene, more preferably 10-30% by weight of ethylene, and preferably 1-20% by weight of (meth)acrylic esters of unbranched or branched alcohols having 1 to 15 C atoms, more particularly methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, hexyl acrylate or 2-ethylhexyl acrylate; and comonomer mixtures of vinyl acetate, 1-20% by weight of vinyl laurate or vinyl esters of alphabranched carboxylic acid having 9 to 11 C atoms, and also 1-20% by weight of (meth)acrylic esters of unbranched or branched alcohols having to 1 to 15 C atoms, more particularly methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, hexyl acrylate or 2-ethylhexyl acrylate; it being possible for the mixtures to further comprise the aboverecited auxiliary monomers in the stated amounts; and the figures in % by weight for the individual comonomer mixtures add up to 100% by weight in each case.

[0039] Methods known in the art for forming VAE copolymers may be utilized in practicing the polymerization process. In some embodiments, the above-described monomers may in their entirety be introduced as an initial charge or metered into a reactor. Preferably, 0-100 weight percent (wt%), more preferably 2-50 wt%, of the monomers are included in the initial charge, based on the total weight of the monomers, and the remaining quantity of monomers is metered in at a later point in time during the emulsion polymerization.

[0040] The monomer selection and the selection of the weight fractions of the comonomers are selected to result in preferable glass transition temperatures, Tg, ranging from -40°C to +40°C, more preferably -40°C to +25°C, and most preferably -20°C to +20°C. The Tg of the polymers may be determined in a known way by means of Differential Scanning calorimetry (DSC, DIN EN ISO 11357-1 / 2), for example, determined with a calorimeter DSC from Mettler-Toledo, with a heating rate of 10 K / min as midpoint temperature. The Tg may also be calculated approximately in advance using the Fox equation. According to Fox T. G., Bull. Am. Physics Soc. 1 , 3, page 123 (1956), the following is the case : 1 / Tg=x1 / Tg1+x2 / Tg2+ . . . +xn / Tgn, where xn stands for the mass fraction (wt% / 100) of the monomer n, and Tgn is the glass transition temperature, in degrees Kelvin, of the homopolymer of the monomer n. Tg values for homopolymers are listed in Polymer Handbook 2nd Edition, J. Wiley & Sons, New York (1975).

[0041] In the polymerization process, it is possible to use the customary protective colloids and / or emulsifiers, as further described in WO 2010 / 057888 A1.

[0042] According to an exemplary embodiment of the present invention, the protective colloid is preferably one or more partially hydrolyzed or fully hydrolyzed polyvinyl alcohols. An increase in the degree of hydrolysis of a polyvinyl alcohol results in increased water resistance, tensile strength, block resistance, and solvent resistance. Suitable protective colloids include polyvinyl alcohols having a degree of hydrolysis of 80 to 100 mol%, more particularly partially hydrolyzed polyvinyl alcohols having a degree of hydrolysis of 80 to 94 mol% and a Hoppler viscosity, in 4% strength aqueous solution, of 1 to 30 mPa-s (Hoppler method at 20°C, DIN 53015). The stated protective colloids may be obtained by methods known to the skilled person and are added generally in an amount of in total 1 to 20 wt%, with respect to the total weight of the monomers, in the polymerization.

[0043] The polymers in the form of aqueous dispersions are dried in a conventional manner to obtain a dispersible polymer powder. In a preferred embodiment, the polymers may be converted to water-dispersible polymer powders by the spray-drying process, as described in WO 2010 / 057888 A1 , for example. In that case it is usual to add a drying aid in a total amount of 3 to 30 wt%, based on the polymeric constituents of the dispersion. Preferred drying aids include the aforementioned polyvinyl alcohols. The aqueous dispersions may also be spray dried with other drying aids known in the art.

[0044] In an embodiment, the polyvinyl alcohols used as a drying aid are preferably a low molecular weight polyvinyl alcohol. A suitable low molecular weight polyvinyl alcohol may have a viscosity of less than 6 cps and an average molecular weight less than 50,000 g / mol. The polyvinyl alcohols used are more preferably ultra low molecular weight polyvinyl alcohol. A suitable ultralow molecular weight polyvinyl alcohol may have a viscosity of 3 to 4 cps and an average molecular weight range of 13,000 to 23,000 g / mol. In general, decreasing the molecular weight of a polyvinyl alcohol increases solubility and flexibility while decreasing viscosity. Decreased viscosity polyvinyl alcohol improves the yield from spray drying. As an additional benefit, lower viscosity polyvinyl alcohols are generally cheaper. Additionally, an anti-blocking agent may be added during or after the drying step. The VAE copolymer may also be prepared by other methods, including solution polymerization, or bulk (neat) polymerization. A copolymer prepared by solution or bulk polymerization is preferably supplied in a form having a relatively high surface area. For this purpose, for example, the copolymer may be extruded into pellets or granules by conventional processes or otherwise prepared in small particle sizes. The use of water-dispersible powders resulting from emulsion or suspension polymerization followed by drying, in particular, spray drying, reduces blending time of the polymeric sand composition significantly, and thus water dispersible powders are highly preferred.

[0045] Suitable commercially available VAE copolymers may be provided as a polymer powder, for example, polymer powders sold under the mark Vinnapas® by Wacker Chemie AG.

[0046] In an embodiment, the dispersible polymer powder may include one or more fillers. The VAE copolymer is in the form of solid powder, but because it is composed of polymer, surface cohesion is high, and the particle size is not uniform and may be coarsened. The addition of one or more fillers can improve the uniformity of powder size and shape. The filler may be selected from any conventional filler known in the art without limitation, for example, an inorganic filler, an organic filler, or a mixture thereof.

[0047] Non-limiting examples of the inorganic fillers include silica, alumina, barium sulfate, calcium carbonate (CaCO3), magnesium hydroxide, alumina hydroxide, titanium dioxide, clay, mica, wollastonite, talc, magnesium carbonate, carbon black, graphite, carbon nanotubes, or nanosilver. The above-mentioned components may be used singly or in combination of two or more.

[0048] Non-limiting examples of the organic filler may include organic bentonite, polyethylene wax, polypropylene wax, polymethyl methacrylate, polyurethane, silicone resin powder, micronized polyamide, styrene-ethylene / butylene-styrene block copolymers, and rosin esters. These may be used singly or in combination of two or more.

[0049] An average particle diameter D50 of the filler is not particularly limited, and may be appropriately adjusted within a range of the ordinary particle size applicable in the art. For example, the average particle diameter D50 of the filler may be in a range from 1 pm to 30 pm, and specifically in a range from 1 pm to 20 pm. A shape of the filler is not particularly limited, and examples thereof may include spherical, granular, plate, scaly, whisker, rod, filament, or irregular shapes. The inorganic particles having such shapes may be used singly or in combination of two or more. In addition, the filler may also be coated with a surface treating agent such as a coupling agent and a conventional polymer.

[0050] A content of the filler is not particularly limited and may be appropriately adjusted in consideration of the uniformity and physical properties of the dispersible polymer powder. For example, the filler may be included in an amount from 0.1 to 30 wt%, and specifically in a range from 1 to 20 wt%, with respect to the total weight of the dispersible polymer powder.

[0051] According to an embodiment of the present invention, the inorganic mineral binder may be cement, more particularly portland cement, aluminate cement, calcium sulfoaluminate cement, calcium aluminate cement, aluminous cement, high-alumina cement, trass cement, slag cement, magnesia cement, phosphate cement, and blast furnace cement, and also mixed cements, filler cements, flyash, microsilica, slag sand, lime or gypsum. Suitable limes include calcium oxide and calcium hydroxide. Calcium aluminate cement, aluminous cement, high-alumina cement, and lime are preferable inorganic mineral binders. Calcium aluminate cement, aluminous cement, and high-alumina cement are more preferable. Calcium aluminate cement, aluminous cement, and high-alumina cement are collectively referred to as “calcium aluminate cement” hereinafter. In an embodiment, the calcium aluminate cement includes AI2O3in a concentration of 35 wt% or more of, preferably 45 wt% or more, and more preferably 50 wt% or more. The calcium aluminate cement includes CaO in a concentration of 10 wt% or more, preferably 10 to 40 wt%, more preferably 15 to 40 wt%, based on a total weight of the calcium aluminate cement. In an exemplary embodiment, the calcium aluminate cement includes 50 to 75 wt% AI2O3and 25 to 40 wt% CaO, based on a total weight of the calcium aluminate cement.

[0052] In another embodiment, the calcium aluminate cement may optionally include MgO in a concentration of less than 30 wt%, preferably less than 20 wt%, more preferably less than 10 wt%, based on a total weight of the calcium aluminate cement. The calcium aluminate cement may optionally include Fe2O3in a concentration of less than 20 wt%, preferably less than 10 wt%, more preferably less than 5 wt%, most preferably less than 2.5 wt%, based on a total weight of the calcium aluminate cement. It may be desirable to reduce the concentration of Fe2O3to reduce staining. Further, a calcium aluminate cement with a high concentration of Fe2O3requires a longer mixing time to achieve a homogeneous appearance.

[0053] The calcium aluminate cement is selected to have a certain particle size. The particle size may be quantified as a Blaine specific surface, measured according to ASTM C204 or EN 196-6. The calcium aluminate cement has a Blaine specific surface of 1000 to 7000 cm2 / g, preferably 2500 to 5000 cm2 / g, more preferably 3500 to 4500 cm2 / g. The preferred ranges of particle size improve the mixing characteristics of the admixture and increase adhesion of the polymeric sand composition. The particle size may also be selected to optimize set time, as a smaller particle size increases solubility.

[0054] Suitable calcium aluminate cements are commercially available, for example as Ciment Fondu® and Secar® sold by Imerys or calcium aluminate cements sold by Calucem. According to an embodiment of the present invention, the polymeric sand composition may comprise a dust suppressant. The transport and installation of construction sand products can disperse airborne fine silica particles which may cause adverse health effects when inhaled. To mitigate the risk posed such particles, a dust suppressant can be added to the polymeric sand composition. The dust suppressant may be a powdered dust suppressant, an oil-based dust suppressant, or any other dust suppressant known in the art. Preferably, an oil-based dust suppressant is used.

[0055] In an embodiment, the oil-based dust suppressant may include naphthenic oil, paraffin oil or olefin oil derived from petroleum fractions, aromatic oil, mineral oil, vegetable oil, synthetic oil, lubricating oil, or any related oil known in the art. The above-mentioned oils may be used singly, or at least two or more oils may be used in combination. As used herein, the oil in which the number of carbon atoms of a paraffinic hydrocarbon accounts for 50% or more of the total carbon atoms is referred to as a paraffinic oil, the oil in which the number of carbon atoms of a naphthenic hydrocarbon accounts for 30 to 45% of the total carbon atoms is referred to as a naphthenic oil, and the oil in which the number of carbon atoms of an aromatic hydrocarbon accounts for 35% or more of the total carbon atoms is referred to as an aromatic oil.

[0056] In a preferred embodiment, the oil-based dust suppressant is mineral oil. Mineral oil is a fastdrying and clear, colorless oil. Due to these characteristics, mineral oil may be added to a polymeric sand composition with minimal effect on color, appearance, or other aesthetic characteristics.

[0057] According to an embodiment of the present invention, the sand is primarily composed of sand grains, with a grain size of 1 / 16 mm to 2 mm. The sand may optionally include pebbles (2 mm to 64 mm), silt (1 / 256 mm to 1 / 16 mm), and clay (>1 / 256 mm). Preferably, the pebbles are fine (4 mm to 8 mm) or very fine (2 mm to 4 mm). Preferably, the sand includes less than 20% pebbles, more preferably less than 10% pebbles. The inclusion of particles larger than sand grains may improve the shear strength of the polymeric sand composition but decreases the surface area of the sand and may result in reduced adhesion. Large grains may also hinder the installation of the polymeric sand composition between closely positioned pavers.

[0058] The sand may be a naturally occurring organic or inorganic material. The sand may also be produced by the decomposition of larger natural or synthetic materials and may include materials of the appropriate size such as stone dust, crushed rock, concrete millings, asphalt millings, crushed slag, crumb rubbers, ground plastics, recycled plastics, and combinations thereof. In a preferred embodiment, the sand includes river sand, crushed sand, angular sand, round sand, crushed slag, pit sand, sea sand, beach sand, silica sand, tan sand, black sand, granitic sand, and combinations thereof.

[0059] In an embodiment, the admixture is prepared by thoroughly mixing an inorganic mineral binder with a dispersible polymer powder. The polymeric sand composition is prepared by thoroughly mixing the admixture into sand. In another embodiment, each component of the admixture may be added directly to the sand to form the polymeric sand composition. The optional dust suppressant may also be added to the sand and included in the polymeric sand composition. The dust suppressant may be added at any stage of the mixing process but is preferably added after the dispersible polymer powder and inorganic mineral binder have been mixed with the sand. The dust suppressant may be added at a concentration of up to 0.5 wt%, preferably 0.05 to 0.5 wt%, more preferably 0.1 to 0.2 wt%, based on a total weight of the polymeric sand composition.

[0060] The polymeric sand composition may be utilized in many applications including the installation of the pavers, stones, flagstones, and other articles used in landscaping or construction. In one such embodiment, a foundation is constructed using materials including unmodified sand, gravel, aggregate, rocks, and other suitable materials known in the art. Pavers, stones, flagstones, and other art-recognized equivalents (referred to as “pavers” herein) are then positioned on the foundation. Next, the polymeric sand composition is deposited between the pavers using a broom or brush to sweep the polymeric sand composition into the interstitial spaces. To activate the polymeric sand composition, water is applied in a mist or light spray. The polymeric sand composition is left to set, which increases the resilience of the finished paver installation.

[0061] A polymeric sand composition preferably sets within 16 to 30 hours under ambient conditions, more preferably within 22 to 26 hours. Increasing the set time increases the risk of the paver installation being disturbed by inclement weather before the polymeric sand composition has reached maximum resilience. However, if the set time is decreased to less than 16 hours, the upper layers of the polymeric sand composition may set prematurely and prevent water from penetrating the full depth of the sand, resulting in an incomplete set with diminished resilience.

[0062] In certain embodiments, the polymeric sand composition forms a resilient joint between pavers. Advantageously, the polymeric sand composition may resist cracking, abrasion, and / or scratching, while also being sufficiently pliable to accommodate slight movements of the pavers. Preferably the polymeric sand composition is also resistant to erosion by wind, rain, and foot or vehicle traffic, and can withstand prolonged submersion in water with minimal loss of adhered sand grains.

[0063] EXAMPLES

[0064] The following examples are presented solely for the purpose of further illustrating and disclosing the embodiments of the polymeric sand composition. Examples of the polymeric sand composition include Examples 1-7, which are described below. Comparative Examples, which are not part of the invention, are also described below. Unless stated otherwise, the following compositions are provided in weight percentages. Example 1

[0065] An admixture was prepared by thoroughly mixing 35 wt% of a calcium aluminate cement

[0066] (Ciment Fondu® from Imerys) and 65 wt% of a low-Tg vinyl acetate ethylene copolymer powder (Vinnapas® 5044N from Wacker Chemie AG). A polymeric sand composition was prepared by thoroughly mixing 5 wt% of the admixture and 95 wt% of sand.

[0067] Example 2

[0068] A polymeric sand composition was prepared with the same procedure as Example 1 . Mineral oil is then added to the polymeric sand composition in an amount equivalent to 0.2 wt% of the polymeric sand composition.

[0069] Example 3

[0070] A polymeric sand composition was prepared with the same procedure as Example 1 , except the calcium aluminate cement is Secar® 51 from Imerys having a composition of 52% AI2O3and 37% CaO.

[0071] Example 4

[0072] An admixture was prepared by thoroughly mixing 45 wt% of a calcium aluminate cement (Secar® 51 from Imerys with a composition of 52% AI2O3and 37% CaO) and 55 wt% of a low- Tg vinyl acetate ethylene copolymer powder (Vinnapas® 5044N from Wacker Chemie AG). A polymeric sand composition was prepared by thoroughly mixing 4.5 wt% of the admixture and 95.5 wt% of sand. Mineral oil is then added to the polymeric sand composition in an amount equivalent to 0.2 wt% of the polymeric sand composition. Example 5

[0073] An admixture was prepared by thoroughly mixing 16.5 wt% lime, 28.5% of a calcium aluminate cement (Ciment Fondu® from Imerys), and 55 wt% of a vinyl acetate ethylene copolymer powder (Vinnapas® 5343E from Wacker Chemie AG). A polymeric sand composition was prepared by thoroughly mixing 4.5 wt% of the admixture and 95.5 wt% of sand.

[0074] Example 6

[0075] A polymeric sand composition was prepared with the same procedure as Example 5, except the vinyl acetate ethylene copolymer powder is Vinnapas® 7034E from Wacker Chemie AG.

[0076] Example 7

[0077] An admixture was prepared by thoroughly mixing 25 wt% lime and 75 wt% of a low-Tg vinyl acetate ethylene copolymer powder (Vinnapas® 5044N from Wacker Chemie AG). A polymeric sand composition was prepared by thoroughly mixing 5 wt% of the admixture and 95 wt% of sand.

[0078] Comparative Example 1

[0079] A commercial polymeric sand composition is provided with a composition of at least 93% sand and gravel, at least 1 % crystalline silica, and less than 7% of a polymer blend. The polymer blend includes a dispersible polymer powder without a crosslinker.

[0080] Comparative Example 2

[0081] A commercial polymeric sand composition is provided with a composition of at least 93% sand and gravel, at least 1 % crystalline silica, and less than 7% of a polymer blend. The polymer blend includes polyvinyl alcohol without a crosslinker. Comparative Example 3

[0082] A commercial polymeric sand composition is provided with a composition of at least 93% sand and gravel, at least 1 % crystalline silica, and less than 7% of a polymer blend. The polymer blend includes a dispersible polymer powder without a crosslinker.

[0083] Set Time Test

[0084] The provided examples were tested for set time and resilience. A sample disk of polymeric sand composition was prepared for testing. Evenly spaced holes were drilled the lid of a 1 -gallon pail to allow drainage and simulate the drainage structure provided beneath a typical paver installation. A weed barrier was cut to the radius of the lid and applied to the surface of the lid to prevent the sand passing through the holes of the lid. The polymeric sand composition was applied onto the weed barrier and struck off using a spatula or knife to achieve a smooth, even surface.

[0085] The samples were wetted with a handheld spray bottle at 5-minute intervals to set the polymeric sand composition. 10 g of water were applied initially. After 5 minutes, a further 40 g of water were applied. After 10 minutes, a further s g of water were applied. After 15 minutes, a further 4 g of water were applied.

[0086] A Gillmore Apparatus was used to determine the set time of each sample as per ASTM C266- 21. The Gillmore Apparatus consists of two horizontally positioned arms, carrying weighted needles. The initial needle has a 2.12 mm diameter and a 113.4 g weight, and the final needle has a 1 .06 mm diameter and a 453.6 g weight. Only the final set was measured in this test.

[0087] Immersion Test

[0088] Upon curing, the disks were removed from the lids and the weed barrier was removed from beneath the disks. The disks were then immersed 5 times in a bucket of water, then left immersed in the bucket for a period of 24 hours. Following the 24-hour immersion, the disks were removed from the bucket, leaving behind the loose sand that eroded from the disk. The eroded sand was decanted and dried in a 70 °C oven for 4 hrs. The eroded sand was then weighed as a means of measuring the water resistance and early erosion resistance of the sample. The results of the set time are shown in the following Table 1 .

[0089] TABLE 1

[0090] All samples tested demonstrated a set time within the preferred range. The preferred set times allow for water to fully penetrate the sand composition while also decreasing the risk of a premature disturbance. However, the examples of the inventive polymeric sand composition demonstrate significantly improved resilience, indicated by the average weight of the eroded sand.

[0091] Scratch Test

[0092] The sample disks were further cured outside for 24 hours at 84 °F (29 °C). The cured sample disks were additionally subjected to a scratch resistance and surface hardness test. A Ri Ri tester provided by Esska.uk, item number 355316140740, was used to apply a constant force for the scratch test. The Ri Ri tester was used to apply 6 scratches to the surface of the sample at a force of 1 kN. The scratches were applied in a hashtag manner, with a first 3 parallel scratches applied in a first direction, and a second 3 parallel scratches applied in a second direction, perpendicular to the first direction. The material removed from the scratch test was weighed to measure the scratch resistance. Each sample was further evaluated visually to determine the severity of the scratch. The results of the scratch test are shown in the following Table 2.

[0093] TABLE 2

[0094] All tested samples exhibited good physical resistance in the scratch test, indicated by the weight of the removed material. However, the scratches on Examples 3 and 4 were significantly less visible than the scratches on Comparative Examples 1 and 2. When scratched, Comparative Examples 1 and 2 reveal a white or light-colored matrix adhering to the sand grains. This matrix is highly visible against the sand. When scratched, Examples 3 and 4 reveal a colorless matrix, which significantly decreases the visibility of scratches in the samples. FIG. 1 shows a scratch test result of Example 3, FIG. 2 shows a scratch test result of Example 4, FIG. 3 shows a scratch test result of Comparative Example 1 , and FIG. 4 shows a scratch test result of Comparative Example 4.

[0095] From the foregoing detailed description, it will be apparent that various modifications, additions, and other alternative embodiments are possible without departing from the true scope and spirit. The embodiments and examples discussed herein were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to use the invention in various embodiments and with various modifications as are suited to the particular use contemplated. As should be appreciated, all such modifications and variations are within the scope of the invention.

Claims

CLAIMS1. A polymeric sand composition, comprising: a sand, and an admixture, wherein said admixture comprises a dispersible polymer powder and an inorganic mineral binder, wherein a weight ratio of the polymer powder to the inorganic mineral binder in the admixture is greater than or equal to 40 / 60 and less than or equal to 90 / 10, wherein the dispersible polymer powder comprises a VAE copolymer having a vinyl acetate content of at least 50 wt% based on a total weight of the VAE copolymer, wherein the admixture is disposed in the polymeric sand composition at a concentration of 2-20 wt% based on a total weight of the polymeric sand composition.

2. The polymeric sand composition according to claim 1 , wherein the inorganic mineral binder comprises a calcium aluminate cement.

3. The polymeric sand composition according to claim 2, wherein the calcium aluminate cement comprises at least 35 wt% AI2O3and 10 to 50 wt% CaO, based on a total weight of the calcium aluminate cement.

4. The polymeric sand composition according to claim 3, wherein the calcium aluminate cement comprises at least 45 wt% AI2O3 and 10 to 40 wt% CaO, based on a total weight of the calcium aluminate cement.

5. The polymeric sand composition according to claim 4, wherein the calcium aluminate cement comprises 50 to 75 wt% AI2O3and 25 to 40 wt% CaO, based on a total weight of the calcium aluminate cement.

6. The polymeric sand composition according to claim 1 , wherein the inorganic mineral binder comprises lime or Portland cement.

7. The polymeric sand composition according to claim 1 , wherein the VAE copolymer has an ethylene content of at least 1 wt% and less than 50 wt%, based on a total weight of the VAE copolymer.

8. The polymeric sand composition according to claim 7, wherein the VAE copolymer has an ethylene content of at least 1 wt% and less than 30 wt%, based on a total weight of the VAE copolymer.

9. The polymeric sand composition according to claim 1 , wherein the VAE copolymer has a glass transition temperature (Tg) between -40°C and 40°C.

10. The polymeric sand composition according to claim 9, wherein the VAE copolymer has a glass transition temperature (Tg) between -20°C and 20°C.11 . The polymeric sand composition according to claim 1 , wherein the polymeric sand composition comprises a dust suppressant in a concentration of up to 0.5 wt%, based on a total weight of the polymeric sand composition.

12. The polymeric sand composition according to claim 11 , wherein the dust suppressant comprises an oil.

13. The polymeric sand composition according to claim 12, wherein the oil has a concentration of 0.05 to 0.5 wt%, based on a total weight of the polymeric sand composition.

14. The polymeric sand composition according to claim 12, wherein the oil is a mineral oil.

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