Cement-based composition comprising a powdered polyurethane

Abstract

The invention relates to a cement-based composition, in particular a dry mortar, comprising a) 5 to 50 parts by mass, preferably 10 to 45 parts by mass, more preferably 15 to 29 parts by mass of a composite hydraulic binder, b) 0.1 to 4 parts by mass, preferably 0.5 to 3 parts by mass, more preferably 1 to 2 parts by mass of a powdered polyurethane, and c) optionally 50 to 90 parts by mass, preferably 60 to 85 parts by mass of an aggregate. The cement-based composition of the invention is particularly useful as a cement-based tile adhesive, as part of a rendering or as part of a rendering system.

Description

Technical Field

[0001] This invention relates to a cement-based composition, particularly dry mortar, comprising powdered polyurethane, especially recycled polyurethane material. Another object of the invention is the use of the cement-based composition and the hardened cement-based composition. Background of the Invention

[0003] Cement-based compositions are widely known for use as plastering, tile adhesives, or insulation systems. It is generally desirable for such cement-based compositions to have a low density in their fresh state, i.e., when mixed with water and before hardening. This low density allows for particularly efficient application, meaning less weight is applied to a given geometry. Typically, lightweight fillers such as expanded clay, pumice, or hollow glass spheres are used.

[0004] Another desirable property of cement-based compositions is high deformability. For example, cement-based compositions used as cement-based tile adhesives must meet specific requirements specified, for example, in the international standard EN 12004-1. To achieve the performance requirements of deformable and highly deformable cement-based tile adhesives according to this standard, a large amount of soft synthetic latex polymer is typically formulated into the cement-based tile adhesive. This synthetic latex polymer is expensive and has an increased carbon footprint.

[0005] Therefore, there has always been a need to improve the fresh density and deformability of cementitious compositions. In light of recent efforts toward more sustainable products, there is also a desire to achieve this using readily available materials, particularly recycled materials.

[0006] Due to their versatility, polyurethanes have seen rapid growth in scale globally over the past few decades. Among the various forms of polyurethane used, polyurethane foams, as well as polyurethane adhesives and sealants, have been widely adopted. With continued growth in scale, the recycling and reuse of this polyurethane is becoming increasingly important as an alternative to incineration or deposition in landfills. Recycled polyurethane materials have been considered a potential replacement for aggregates in cement-based compositions (see, for example, C. Junco et al., Cement & Concrete Composites, 2012, 34, 1174-1179). However, it has been shown that if polyurethane materials are used to replace aggregates, strength development, in particular, may be negatively impacted.

[0007] WO 2013 / 062986 (Dow Global Technologies) discloses the use of blends of powdered flexible polyurethane foam with redispersible polymer powder. The use of such blends in cement-based tile adhesives results in improved tensile bond strength after water immersion. However, the deformability of the materials described therein is significantly reduced, particularly compared to compositions that do not contain powdered polyurethane.

[0008] Therefore, it is desirable to use powdered polyurethane, especially recycled powdered polyurethane, and cement-based compositions with improved deformability. Invention Overview

[0010] One object of the present invention is to provide a cement-based composition comprising powdered polyurethane and having improved deformability. This composition is particularly suitable for use as a cement-based tile adhesive or in thermal insulation systems.

[0011] The object of the present invention is achieved by a cement-based composition according to the following description. The cement-based composition is based on a composite hydraulic binder, powdered polyurethane, and optionally aggregates. The composite hydraulic binder comprises CEM I, CEM II, CEM III, CEM IV, CEM V, or CEM VI according to EN 197-1:2018, and at least one auxiliary binder selected from CEM II, CEM III, CEM IV, CEM V, or CEM VI according to EN 197-1:2018.

[0012] One advantage of the compositions of the present invention is that their deformability (measured as transverse deformation after 28 days of hardening according to standard EN 12002:2009) is significantly improved compared to similar compositions that are based solely on ordinary Portland cement as a binder.

[0013] Another advantage of the present invention is that the fresh density of the cement-based composition can be reduced compared to the same composition without using powdered polyurethane. Invention Details

[0015] In a first aspect, the present invention relates to a cement-based composition, particularly a dry mortar, characterized in that it comprises...

[0016] a) 5-50 parts by weight, preferably 10-45 parts by weight, more preferably 15-29 parts by weight of a composite hydraulic binder,

[0017] b) 0.1-4 parts by weight, preferably 0.5-3 parts by weight, more preferably 1-2 parts by weight of powdered polyurethane, and

[0018] c) Optional 50-90 parts by weight, preferably 60-85 parts by weight of aggregate.

[0019] In a preferred embodiment, the present invention relates to cement-based compositions, particularly dry mortars, characterized in that they comprise (in each case, by the total dry weight of the cement-based composition).

[0020] a) 5-50% by weight, preferably 10-45% by weight, more preferably 15-29% by weight of a composite hydraulic binder.

[0021] b) 0.1-4% by weight, preferably 0.5-3% by weight, more preferably 1-2% by weight of powdered polyurethane, and

[0022] c) Optional 49-91% by weight, preferably 60-84% by weight of aggregate.

[0023] In the context of this invention, dry mortar is a cement-based composition with a water content of no more than 10% by weight, preferably no more than 3% by weight, and especially no more than 1% by weight, in each case relative to the total weight of the cement-based composition.

[0024] The cement-based composition of the present invention comprises a composite hydraulic binder. According to a first embodiment, the composite hydraulic binder comprises CEM I, CEM II, CEM III, CEM IV, CEM V, or CEM VI according to EN 197-1:2018 and at least one auxiliary binder. According to a further embodiment, the composite hydraulic binder is selected from CEM II, CEM III, CEM IV, CEM V, or CEM VI according to EN 197-1:2018. However, various cements according to other standards, such as ASTM standards, Chinese or Indian standards, are equally suitable.

[0025] According to the implementation scheme, the auxiliary cementing material is selected from calcined clay, fly ash, silica fume, tuff, volcanic ash, pumice, perlite, diatomaceous earth, rice husk ash, burnt shale, limestone, slag, and mixtures thereof. According to a preferred implementation scheme, the auxiliary cementing material is selected from slag, particularly preferably from ground granular blast furnace slag and / or from alkaline oxygen furnace slag.

[0026] The composite hydraulic binder of the present invention is preferably a mixture comprising ordinary Portland cement and at least one auxiliary binder. Ordinary Portland cement is preferably CEM I according to EN 197-1:2018. However, ordinary Portland cement according to other standards is also possible.

[0027] According to embodiments, the composite hydraulic binder of the present invention comprises CEM I, CEM I, CEM III, CEM IV, CEM V or CEM VI according to EN 197-1:2018 and at least one auxiliary bonding material. According to different embodiments, the composite hydraulic binder comprises CEM II, CEM III, CEM IV, CEM V or CEM VI according to EN 197-1:2018.

[0028] However, it is possible, and in some cases preferred, that the composite hydraulic binder of the present invention additionally contains other minerals. Examples of such other minerals are calcium sulfate, especially anhydrite, calcium sulfate in the form of α- or β-hemihydrate or dihydrate, calcium aluminate, high-alumina cement, calcium sulfoaluminate cement, and lime, especially in the form of natural hydraulic lime, formulated lime, hydraulic lime, and / or air lime conforming to standard EN 459-1:2015. If present, the content of such other minerals can vary over a wide range. This content can, for example, vary from about 1% by weight to about 20% by weight, relative to the total dry weight of the cementitious composition. According to the embodiments, the composite hydraulic binder of the present invention may therefore contain CEM I, CEM II, CEM III, CEM IV, CEM V or CEM VI according to EN 197-1:2018, at least one auxiliary binder and one or more other minerals selected from calcium sulfate (especially in the form of anhydrite, α- or β-hemihydrate or dihydrate), calcium aluminate, high alumina cement, calcium sulfoaluminate cement and lime (especially in the form of natural hydraulic lime, prepared lime, hydraulic lime and / or air-hardening lime conforming to standard EN 459-1:2015). Depending on the implementation, the composite hydraulic binder comprises CEM II, CEM III, CEM IV, CEM V or CEM VI according to EN 197-1:20 18 and one or more other minerals selected from calcium sulfate (especially anhydrite, α- or β-hemihydrate or dihydrate form), calcium aluminate, high-alumina cement, calcium sulfoaluminate cement and lime (especially in the form of natural hydraulic lime, prepared lime, hydraulic lime and / or air-hardening lime conforming to standard EN 459-1:2015).

[0029] According to a preferred embodiment, the weight ratio of any one of CEM I, CEM II, CEM III, CEM IV, CEM V or CEM VI in the cement-based composition of the present invention to the auxiliary binder is 16:1-1:5, preferably 10:1-1:2, and more preferably 4:1-1:1.

[0030] The cement-based composition of the present invention comprises powdered polyurethane. Throughout this context, the term "powdered polyurethane" refers to a material in a solid physical state at 23°C, characterized by a particle size distribution and containing a polymer comprising a plurality of urethane groups. Specifically, powdered polyurethane is a ground polyurethane material obtained by grinding any flexible or rigid polyurethane material or polyurethane foam into powder. Preferably, the polyurethane powder of the present invention is obtained by grinding a flexible or elastic polyurethane at 23°C. Still more preferably, the powdered polyurethane of the present invention is obtained in the process of recycling polyurethane or polyurethane-containing materials. In particular, the powdered polyurethane of the present invention is a recycled product from flexible PU foam insulation boards.

[0031] In this context, polyurethane (PU) is any polymer composed of organic unit chains linked by carbamate bonds. Urea bonds may also be present. PU polymers are formed by stepwise growth polymerization or addition polymerization, by reacting a monomer having at least two isocyanate functional groups with another monomer having at least two hydroxyl functional groups, preferably in the presence of a catalyst.

[0032] The particle size distribution of powdered polyurethane can be analyzed by sieving analysis, for example, as described in the standard ASTM C136 / C136M. This method separates fine particles from coarse particles by passing the material through sieves of multiple different mesh sizes. The material to be analyzed is vibrated using a single horizontal, vertical, or rotary motion, or a combination thereof, to pass through a series of sieves with progressively decreasing mesh sizes. Alternatively, analysis can be performed by air-jet sieving, which is particularly useful when analyzing particles <100 μm in size. As a result, the percentage of particles that pass through a sieve of a given size is obtained. Throughout this document, any lower value in the range given for particle size represents the D10 value of the corresponding particle size distribution, while any higher value in the range given for particle size represents the D90 value of the corresponding particle size distribution. In other words, the lower values ​​of these ranges correspond to particle sizes where only 10% of all particles have a smaller particle size, while the upper values ​​of these ranges correspond to particle sizes where only 10% of all particles have a larger particle size. The average particle size specifically corresponds to the D50 value (50% of the particles are smaller than a given value, and 50% are correspondingly larger).

[0033] The particle size of the powdered polyurethane of the present invention can vary over a wide range. According to embodiments, the particle size of the powdered polyurethane can be in the range of 0.5 μm-8 mm, preferably 0.8 μm-5 mm, more preferably 10 μm-3 mm, and especially 50 μm-1 mm or 1 mm-3 mm. According to embodiments, the D50 of the powdered polyurethane of the present invention can be between 10-1000 μm, preferably between 50-500 μm.

[0034] In the context of this invention, powdered polyurethane derived from recycled polyurethane foam or polyurethane-based adhesives or sealants can be used.

[0035] Polyurethane foam can be obtained as flexible or rigid foam. Polyurethane adhesives can be obtained as elastic adhesives or sealants. According to a preferred embodiment, the powdered polyurethane of the present invention is obtained by recycling polyurethane foam from furniture cushions, car seat cushions, carpet cushions, mattress pads, solid mattress cores, car headliners, building foams, insulation boards, fire retardants, wheels, etc. According to another preferred embodiment, the powdered polyurethane of the present invention is obtained from the recycling of polyurethane adhesives or sealants. However, it is also preferred to use powdered polyurethane from waste manufacturing or cutting processes. In particular, the powdered polyurethane of the present invention is recycled from flexible PU foam insulation boards. Using recycled polyurethane powder is environmentally friendly and reduces the cost of cement-based dry-mix formulations. Preferably, during the polyurethane recycling process, the material is first shredded and then ground to the desired particle size. The ground material can be sieved to separate fine particles from coarse particles. The powdered polyurethane can be further treated with anti-caking agents such as silica or chalk.

[0036] The powdered polyurethane of the present invention may contain conventional amounts of typical additives used in the preparation of polyurethane foams or polyurethane adhesives, such as fillers, surfactants, chain extenders, plasticizers, crosslinking agents, flame retardants, foaming agents and / or pigments.

[0037] The cement-based composition of the present invention optionally contains 50-90 parts by weight, preferably 60-85 parts by weight of aggregate. In a preferred embodiment, the cement-based composition of the present invention contains (in each case, relative to the total dry weight of the cement-based composition) 49-91% by weight, preferably 60-84% by weight of aggregate.

[0038] Aggregates can be any material that is non-reactive in the hydration reaction of cementitious binders. Aggregates can be any aggregate commonly used in cementitious compositions. Typical aggregates include, for example, rock, crushed stone, gravel, slag, sand (especially quartz sand, river sand, and / or manufactured sand), recycled concrete, glass, expanded glass, hollow glass beads, glass ceramics, volcanic rock, pumice, perlite, vermiculite, quarry waste, raw, fired, or molten soil or clay, porcelain, electrofused or sintered abrasives, fired carriers, silica dry gel, and / or fine aggregates (also known as fillers, such as ground limestone, ground dolomite, and / or ground alumina). Aggregates used in this invention can have any shape and size typically encountered. Particularly preferred aggregates are sand. Sand is a naturally occurring granular material composed of finely divided rock or mineral particles. It can be obtained in various forms and sizes. Examples of suitable sand are quartz sand, limestone sand, river sand, or crushed aggregates. Suitable sands are described, for example, in standards ASTM C778 or EN 196-1. According to embodiments, at least a portion of the sand used in the cementitious compositions of the present invention is quartz sand, river sand, manufactured sand (e.g., from granite or limestone), or mixtures thereof. According to a preferred embodiment, river sand is used in the cementitious compositions of the present invention because it is chemically inert, robust, available in various sizes, and can advantageously set the processability of the composition. Typically, the sand is supplied in different particle sizes through a sieve with transparent openings. According to embodiments, sand having 99% of the particles having a size of 1 mm or less, preferably 0.8 mm or less, especially 0.6 mm or less (measured according to ASTM C136 / 136M in each case) is used in the cementitious compositions of the present invention. However, for the cementitious compositions of the present invention, sand having particles larger than 1 mm, such as 2 mm or larger, may also be used. The choice of sand particle size depends largely on the end use of the cementitious composition. It may be particularly preferred to use sand with different particle size distributions to optimize the grading profile. Methods for optimizing the grading profile are known to those skilled in the art.

[0039] According to the implementation plan, the aggregate may also be one or more of the following (i)-(iv):

[0040] (i) Biologically derived materials, preferably plant-derived, more preferably plant-derived biologically derived materials consisting essentially of cellulose and / or lignin, especially biologically derived materials selected from the group consisting of: hemp, flax, cereal straw, oats, rice, rapeseed, corn, sorghum, flax, miscanthus, rice husks, sugarcane, sunflower, kenaf, coconut, olive pit, bamboo, wood, or mixtures thereof. According to the embodiment, the plant-derived biologically derived material has a defined form, preferably selected from fibers, fibrils, dust, powder, shavings, pith, especially the pith of sunflower, corn, and rapeseed, and mixtures thereof.

[0041] (ii) Synthetic non-mineral materials other than polyurethane or polyurethane-based materials, preferably selected from thermoplastics, thermosetting plastics, elastomers, rubbers, textile fibers, and plastic materials reinforced with glass or carbon fibers. The synthetic non-mineral materials may be filled or unfilled.

[0042] (iii) Inorganic aggregates derived from civil engineering or building structure deconstruction, preferably selected from the group consisting of or including: waste concrete, mortar, brick, natural stone, asphalt, ceramic tiles, roof tiles, aerated concrete, clinker, and waste metal.

[0043] (iv) Harmless particulate materials commonly used in landfills, such as used foundry sand, catalyst carriers, Bayer descaling carriers, clinker aggregates, fillers from excavated sludge treatment, sewage sludge, waste paper, waste paper incineration ash, and household waste incineration ash.

[0044] Most preferably, the aggregate is in granular form. There are no particular limitations on the particle size of the aggregate, and it can vary within the range typically encountered for aggregates used in cement-based compositions, particularly mortars.

[0045] According to embodiments, the cement-based composition of the present invention comprises 50-90 parts by weight, preferably 60-85 parts by weight of sand. In a preferred embodiment, the cement-based composition of the present invention comprises (in each case, relative to the total dry weight of the cement-based composition) 49-91% by weight, preferably 60-84% by weight of sand.

[0046] In the presence of aggregates, the volume ratio of powdered polyurethane to the total combined volume of powdered polyurethane and aggregates is preferably 2-20% by volume, more preferably 2-10% by volume, and particularly 3-9% by volume. To calculate the volume percentage, the bulk density of the corresponding material is used.

[0047] When aggregates are present, it is preferable that the particle size of the powdered polyurethane matches that of the aggregates to ensure a sufficiently high filling density. In other words, the sieving profile of this cementitious composition can be optimized by taking into account the particle size of the powdered polyurethane. Methods for optimizing the sieving profile are known to those skilled in the art.

[0048] Cement-based compositions may advantageously further comprise materials commonly used in the mortar and / or concrete industry, such as fillers, plasticizers and / or superplasticizers, air-entraining agents, defoamers, stabilizers, rheology modifiers, especially thickeners, water-reducing agents, redispersible polymer powders, accelerators, retarders, waterproofing agents, strength-enhancing additives, fibers, dust removers, foaming agents, pigments, corrosion inhibitors, biocides, and chromium (VI) reducing agents. It may be advantageous to combine two or more of the other mentioned materials in a cement-based composition.

[0049] The cement-based compositions of the present invention, particularly dry mortars, can be prepared by conventional methods of mixing the components, particularly cement, auxiliary cementitious materials, powdered polyurethane, and optional aggregates and / or any other materials as defined above. Suitable mixers are, for example, horizontal single-shaft mixers, twin-shaft paddle mixers, vertical shaft mixers, belt mixers, track mixers, tank changer mixers, tumbling vessels, vertical mixing chambers, or air-mixing operations. Mixing can be continuous or intermittent.

[0050] According to a preferred embodiment, the cement-based compositions of the present invention, particularly dry mortars, are single-component mixtures. This means that all individual components are mixed with each other. Single-component compositions are particularly easy to handle and eliminate the risk of users mixing or mis-measuring the individual components.

[0051] However, in principle, the cement-based compositions of the present invention can be provided as two-component or even multi-component compositions, especially dry mortars. Two-component or multi-component compositions allow, for example, the cement-based composition to be adjusted according to the specific application.

[0052] On the other hand, the present invention also relates to a processable composition comprising the cement-based composition as described above, particularly dry mortar, and further comprising water, wherein the water / powder weight ratio is 0.1-0.6, preferably 0.2-0.5, particularly 0.2-0.35. The term powder refers to the dry cement-based composition as described above.

[0053] The water can be any available water, such as distilled water, purified water, tap water, mineral water, spring water, and well water. Wastewater may be used only if its composition is known and its impurities do not impart the functionality to any of the other components of the composition of the invention. The use of brine is not preferred because of its high chloride content and the associated risk of steel reinforcement corrosion.

[0054] Typically, dry cementitious compositions are mixed with water only shortly before application. This is because the dry cementitious compositions of the present invention will begin to harden upon contact with water. Therefore, it is particularly preferred to first prepare the dry cementitious composition, especially dry mortar, as described above, and then mix the dry cementitious composition with water at or near the application site.

[0055] There are no particular limitations on the methods and equipment used to mix dry cement-based compositions with water, and these are known to those skilled in the art. Mixing can be continuous, semi-continuous, or batch mixing. Continuous mixing offers the advantage of high material yield.

[0056] In the context of this invention, cement-based compositions containing water also refer to wet compositions.

[0057] According to embodiments, the dry cement-based composition described above is particularly a portion of a dry mortar, premixed mortar, or dry concrete composition. According to further embodiments, the dry cement-based composition described above is particularly in the form of a dry mortar, premixed mortar, or dry concrete composition. The dry mortar, premixed mortar, or dry concrete composition herein may be in the form of a single-component material. However, the dry composition herein may also be in the form of a multi-component material, such as a two-component or three-component material. According to further embodiments, the dry composition described above is prepared in the workplace, for example, by mixing at least one component with other components of the dry composition and / or by mixing two or more components of a multi-component material.

[0058] In another aspect, the present invention relates to the use of the cement-based composition as described above as a cement-based tile adhesive, grouting material, self-leveling underlayment, self-leveling overlay, plaster, repair mortar, thin-joint mortar or concrete, leveling layer, wall leveling agent for internal or external use, non-shrink grout, thin-joint mortar, waterproof mortar, anchoring mortar, shotcrete, filling mortar or masonry mortar.

[0059] Cement-based tile adhesives, especially those according to standard EN 12004-1. Grouting materials, especially those according to standard EN 13888. Self-leveling underlayment or self-leveling overlay, especially those according to standard EN 13813. Plastering, especially those according to standard EN 998-1. Repair mortar, especially those according to standard EN 1504-3. Masonry mortar or concrete, especially those according to standards EN 998-2 and EN 206-1. Leveling layer, especially those according to standard EN 13813. Non-shrink grouting, especially those according to standard EN 1504-6. Thin joint mortar, especially those according to standard EN 998-2. Waterproof mortar, especially those according to standard EN 1504-2. Anchoring mortar, especially those according to standard EN 1504-6. Shotcrete, especially those according to standard EN 1504-5.

[0060] According to a preferred embodiment, the cement-based composition of the present invention or the processable cement-based composition as described above is used as a cement-based tile adhesive. According to another preferred embodiment, the cement-based composition of the present invention or the processable cement-based composition as described above is used as part of plastering or a plastering system.

[0061] Typically, this application involves wet compositions, i.e., cement-based compositions that also contain water and have a water / powder ratio of 0.1-0.6, preferably 0.2-0.5, and especially 0.2-0.35. The weight ratio of water to powder is adjusted to control the rheological properties of the wet composition. Higher amounts of water result in a more flowable wet composition, while lower amounts form a paste-like wet composition. The rheological properties can be adjusted by the amount of water to produce wet compositions with rheological properties ranging from self-leveling to very thick.

[0062] The wet composition of the present invention can be applied in any manner known to those skilled in the art. According to one embodiment, the wet composition is applied by a trowel, notch trowel, brush, or roller. According to another embodiment, the wet composition is applied by spraying. According to yet another embodiment, the wet composition is poured from a suitable container.

[0063] The advantage of spray application is that it can be performed very quickly and continuously. Suitable equipment for such spray application is known to those skilled in the art. According to a particularly preferred embodiment, the method of the present invention is carried out continuously. This method is characterized by the continuous mixing and supplying of water and a dry cementitious composition to the nozzle. This allows for continuous spray application.

[0064] The wet composition of the present invention can be applied in a single layer or multiple layers. The advantage of applying in multiple layers is that a higher total layer thickness can be obtained.

[0065] The primer can be applied to the substrate before applying the wet composition of the present invention. Alternatively, the primer can be applied between different layers of the wet composition of the present invention during multi-layer application.

[0066] When mixed with water, the cement-based composition of the present invention will begin to set and harden. The setting and hardening of the wet composition of the present invention occurs over time, thereby producing physical properties such as compressive strength, tensile bond strength, etc. The wet composition of the present invention will harden at various temperatures. However, it is preferred to harden the wet composition of the present invention at temperatures from +1°C to +50°C, more preferably from +5°C to +35°C. It is highly preferred to harden the wet composition of the present invention at a pressure of about 1023 mbar. The wet composition of the present invention can also be hardened and cured at higher temperatures and increased pressures, for example, in an autoclave. Hardening is typically completed after 28 days. However, depending particularly on temperature, pressure, and humidity, hardening may be completed in less than 28 days or may continue for more than 28 days.

[0067] One advantage of the compositions of the present invention is that their deformability (measured as transverse deformation after 28 days of hardening according to standard EN 12002:2009) is significantly improved compared to similar compositions that are based solely on ordinary Portland cement as a binder.

[0068] Another advantage of this invention is that, by incorporating powdered polyurethane, the fresh density of the cement-based composition can be reduced compared to the same composition without powdered polyurethane. The reduced density is advantageous because such a material is easier to apply and adds less weight to a given carrier (e.g., a facade).

[0069] According to the embodiments, the cement-based composition of the present invention has a fresh density measured according to standard EN 1015-6:2007, which is lower than the fresh density of the same material but containing aggregates instead of powdered polyurethane. Lower means a reduction in density, for example, a reduction of 1%, preferably 5%, more preferably 10%.

[0070] Polyurethane foam or powdered polyurethane foam is particularly preferred for use in the cement-based compositions of the present invention. Such polyurethane foam or powdered polyurethane foam is as described above. If the powdered polyurethane material, such as milled polyurethane foam, is too fine, air will be lost and will not result in a decrease in the fresh density of the cement composition.

[0071] The addition of powdered polyurethane according to the invention affects the water requirement of cement-based compositions based on the composite binder described above. Compared to the same cement-based composition without powdered polyurethane, the cement-based composition containing powdered polyurethane requires more water to achieve the same workability.

[0072] The above advantages are highly relevant to cement-based tile adhesives, grouting materials, self-leveling underlayment, self-leveling overlay, plastering, repair mortar, thin-joint mortar or concrete, leveling layer, wall leveling agent for internal or external use, non-shrink mortar, thin-joint mortar, waterproof mortar, anchoring mortar, shotcrete, filling mortar or masonry mortar.

[0073] On the other hand, this application also relates to a method for improving the flexibility of a cement-based composition, the method comprising the following steps:

[0074] a) A mixture of 5-50 parts by weight, preferably 10-45 parts by weight, more preferably 15-29 parts by weight of a composite hydraulic binder, 0.1-4 parts by weight, preferably 0.5-3 parts by weight, more preferably 1-2 parts by weight of powdered polyurethane, optionally 50-90 parts by weight, preferably 60-85 parts by weight of aggregate, optionally other minerals, optionally other additives, and water.

[0075] b) Apply the mixture obtained in step a) to the carrier or pour the mixture obtained in step a) into a mold, and

[0076] c) Harden the mixture to obtain a hardened body.

[0077] In a preferred embodiment, the present invention relates to a method for improving the flexibility of a cement-based composition, the method comprising the following steps:

[0078] a) A mixture (in each case, relative to the total dry weight of the cementitious composition) of 5-50% by weight, preferably 10-45% by weight, more preferably 15-29% by weight, of a composite hydraulic binder; 0.1-4% by weight, preferably 0.5-3% by weight, more preferably 1-2% by weight, of powdered polyurethane; optionally 49-91% by weight, preferably 60-84% by weight, of aggregates; optionally other minerals; optionally other additives; and water.

[0079] b) Apply the mixture obtained in step a) to the carrier or pour the mixture obtained in step a) into a mold, and

[0080] c) Harden the mixture to obtain a hardened body.

[0081] Other preferred embodiments as described above also apply to this aspect.

[0082] In another aspect, the present invention also relates to a method for reducing the density of a workable cementitious composition, the method comprising the steps of:

[0083] a) A mixture of 5-50 parts by weight, preferably 10-45 parts by weight, more preferably 15-29 parts by weight of a composite hydraulic binder; 0.1-4 parts by weight, preferably 0.5-3 parts by weight, more preferably 1-2 parts by weight of powdered polyurethane; optionally 50-90 parts by weight, preferably 60-85 parts by weight of aggregate; optionally other minerals; optionally other additives; and

[0084] b) Mix the mixture obtained in step a) with water at a water / powder ratio of 0.1-0.6, preferably 0.2-0.5, especially 0.2-0.35.

[0085] In a preferred embodiment, the present invention relates to a method for reducing the density of a workable cementitious composition, the method comprising the following steps:

[0086] a) A mixture (in each case, relative to the total dry weight of the cementitious composition) of 5-50% by weight, preferably 10-45% by weight, more preferably 15-29% by weight, of a composite hydraulic binder; 0.1-4% by weight, preferably 0.5-3% by weight, more preferably 1-2% by weight, of powdered polyurethane; optionally 49-91% by weight, preferably 60-84% by weight, of aggregates; optionally other minerals; optionally other additives; and

[0087] b) Mix the mixture obtained in step a) with water at a water / powder ratio of 0.1-0.6, preferably 0.2-0.5, especially 0.2-0.35.

[0088] Other preferred embodiments as described above also apply to this aspect.

[0089] Therefore, in another aspect, a method for simultaneously improving the flexibility and reducing the density of a cementitious composition also relates to, the method comprising the following steps:

[0090] a) A mixture of 5-50 parts by weight, preferably 10-45 parts by weight, more preferably 15-29 parts by weight of a composite hydraulic binder, 0.1-4 parts by weight, preferably 0.5-3 parts by weight, more preferably 1-2 parts by weight of powdered polyurethane, optionally 50-90 parts by weight, preferably 60-85 parts by weight of aggregate, optionally other minerals, optionally other additives, and water.

[0091] b) Apply the mixture obtained in step a) to the carrier or pour the mixture obtained in step a) into a mold, and

[0092] c) Harden the mixture to obtain a hardened body.

[0093] In a preferred embodiment, the present invention relates to a method for simultaneously improving the flexibility of a cement composition and reducing its density, the method comprising the following steps:

[0094] a) A mixture (in each case, relative to the total dry weight of the cementitious composition) of 5-50% by weight, preferably 10-45% by weight, more preferably 15-29% by weight, of a composite hydraulic binder; 0.1-4% by weight, preferably 0.5-3% by weight, more preferably 1-2% by weight, of powdered polyurethane; optionally 49-91% by weight, preferably 60-84% by weight, of aggregates; optionally other minerals; optionally other additives; and water.

[0095] b) Apply the mixture obtained in step a) to the carrier or pour the mixture obtained in step a) into a mold, and

[0096] c) Harden the mixture to obtain a hardened body.

[0097] Other preferred embodiments as described above also apply to this aspect.

[0098] In another aspect, the present invention relates to hardened bodies obtained by hardening the cement-based compositions of the present invention. The present invention particularly relates to hardened cement-based tile adhesives, hardened grouting materials, hardened self-leveling underlayments, hardened self-leveling overlays, hardened plasters, hardened repair mortars, hardened thin-joint mortars or concrete, hardened leveling layers, hardened wall leveling agents, hardened non-shrink grouts, hardened thin-joint mortars, hardened waterproof mortars, hardened anchoring mortars, hardened shotcrete, hardened filling mortars, or hardened masonry mortars, wherein any of the cement-based ceramic adhesives, grouting materials, self-leveling underlayments, self-leveling overlays, plasters, repair mortars, thin-joint mortars or concrete, leveling layers, wall leveling agents, non-shrink mortars, thin-joint mortars, waterproof mortars, anchoring mortars, shotcrete, filling mortars, or masonry mortars comprises or is composed of the hardened cement-based compositions of the present invention.

[0099] Other preferred embodiments as described above also apply to this aspect.

[0100] In a final aspect, the present invention relates to admixtures for cementitious compositions comprising a composite hydraulic binder, wherein the admixture comprises or is substantially composed of powdered polyurethane. Powdered polyurethane is as described above.

[0101] According to one embodiment, the admixture of the present invention comprises powdered polyurethane as described above. According to another embodiment, the admixture comprises powdered polyurethane as described above and aggregates as described above. In yet another embodiment, the admixture comprises powdered polyurethane as described above, aggregates as described above, and optionally other materials commonly found in the mortar and / or concrete industry, such as fillers, plasticizers and / or superplasticizers, air-entraining agents, defoamers, stabilizers, rheology modifiers, especially thickeners, water-reducing agents, redispersible polymer powders, accelerators, retarders, waterproofing agents, strength-enhancing additives, fibers, dust removers, foaming agents, pigments, corrosion inhibitors, biocides, and chromium (VI) reducing agents.

[0102] Other preferred embodiments as described above also apply to this aspect.

[0103] The following examples will provide those skilled in the art with other embodiments of the present invention. They are not intended to limit the invention in any way.

[0104] Example

[0105] Table 1 below shows an overview of the raw materials used.

[0106] Table 1: Raw Materials Used

[0107]

[0108] Test method:

[0109] Unless otherwise specified, curing is carried out at 23°C and 50% RH.

[0110] Fresh density is measured according to standard EN 1015-6:2007.

[0111] The initial tensile bond strength after curing time and the tensile bond strength after 20 minutes open time were measured according to EN 1346:2008, as shown in Tables 2 and 3.

[0112] Transverse deformation was measured according to standard EN 12002:2009 after 28 days of curing.

[0113] Example 1

[0114] Example 1 illustrates the role of various powdered polyurethane materials in composite binder-based cementitious compositions.

[0115] Table 2 below shows reference embodiments Ref-1 to Ref-3 which are not based on the invention, and embodiments 1-1 to 1-3 based on the invention.

[0116] The composition of each mixture is given in Table 1. All figures refer to the mass of each material in grams. OPC, GGBFS, CaCO3, silica sand, recycled PU, and additives were weighed individually and mixed for 3 minutes in a mixing bowl on a Hobart mixer at 23°C / 50% RH. A visually homogeneous dry mixture was obtained. Water was added to the dry mixture in an amount such that the water-to-powder weight ratio (w / p ratio) is as shown in Table 2. Mixing was then continued for 1.5 minutes. Measurements were performed as described above.

[0117] Table 2: Effects of various recycled PUs

[0118]

[0119] nm: Not measured

[0120] As can be seen from Table 2 above, the addition of powdered PU significantly reduces the fresh density of a given cementitious composition (see 1-1 to 1-3 vs Ref-3).

[0121] The adhesion strength results shown in Table 2 indicate that the cement-based compositions of the present invention can achieve sufficiently high values ​​for, for example, C1 type cement-based tile adhesives according to EN 12004-1:2017.

[0122] Furthermore, as can be seen from Table 2, the use of powdered polyurethane in composite binder-based compositions increases lateral deformation compared to the use of powdered polyurethane in pure OPC-based compositions (see Examples 1-1 to 1-3 vs Ref-2).

[0123] Example 2

[0124] Example 2 demonstrates the effect of adding powdered polyurethane to different composite adhesives.

[0125] Table 3 below shows Reference Ref-4, which is not based on the invention, and Examples 2-1 to 2-4, which are based on the invention.

[0126] The compositions of each embodiment are shown in Table 3. All figures refer to the mass (in grams) of each material. Each composition was prepared in the same manner as in Example 1 above.

[0127] Table 3: Effects of various composite adhesives on powdered PU

[0128]

[0129] nm: Not measured

[0130] As can be seen from Table 3 above, the adhesive strength values ​​of formulations 2-1 to 2-4 of the present invention are sufficiently high, thus meeting the requirements of C1 type cement-based tile adhesives according to EN12004-1:2017.

[0131] Furthermore, as can be seen from Table 3, the use of powdered polyurethane in composite binder-based compositions significantly increases lateral deformation compared to the use of powdered polyurethane in pure OPC-based compositions (see Examples 2-1 to 2-4 vs Ref-4).

[0132] Example 3

[0133] Example 3 illustrates the effect of compositional changes in the cement-based composition.

[0134] Table 4 below shows reference embodiments Ref-5 to Ref-7 which are not based on the invention, and embodiments 3-1 to 3-4 which are based on the invention.

[0135] The compositions of each embodiment are shown in Table 4. All figures refer to the mass (in grams) of each material. Each composition was prepared in the same manner as in Example 1 above.

[0136] Table 4: Effect of changes in the composition of cement-based compositions

[0137]

[0138] na: Cannot be applied, therefore cannot be measured.

Claims

1. A method for simultaneously improving the flexibility of a cementitious composition and reducing the density of the cementitious composition, the method comprising the following steps: a) Mix 5-50 parts by weight of a composite hydraulic binder, 0.1-4 parts by weight of powdered polyurethane, optionally 50-90 parts by weight of aggregates, other minerals, optionally other additives, and water. b) Apply the mixture obtained in step a) to the carrier or pour the mixture obtained in step a) into a mold, and c) Harden the mixture to obtain a hardened body; Its features are, The composite hydraulic binder comprises CEM I, CEM II, CEM III, CEM IV, CEM V or CEM VI according to EN 197-1:2018 and an auxiliary binder, wherein the auxiliary binder is a mixture of ground granular blast furnace slag and basic oxygen furnace slag; and the other minerals are selected from calcium sulfate, calcium aluminate, high alumina cement, calcium sulfoaluminate cement and lime.

2. The method according to claim 1, characterized in that... The cement-based composition is dry mortar.

3. The method according to claim 1, characterized in that... The composite hydraulic binder comprises CEM II, CEM III, CEM IV, CEM V or CEM VI according to EN 197-1:2018 and the auxiliary binder.

4. The cement-based composition according to claim 1, characterized in that... The weight ratio of any one of CEM I, CEM II, CEM III, CEM IV, CEM V or CEM VI to the auxiliary binder is 16:1 to 1:

5.

5. The method according to claim 1, characterized in that... The weight ratio of any one of CEM I, CEM II, CEM III, CEM IV, CEM V or CEM VI to the auxiliary binder is 10:1 to 1:

2.

6. The method according to claim 1, characterized in that... The weight ratio of any one of CEM I, CEM II, CEM III, CEM IV, CEM V or CEM VI to the auxiliary binder is 4:1 to 1:

1.

7. The method according to claim 1, characterized in that... The calcium sulfate is in the form of anhydrite, α- or β-hemihydrate, or dihydrate.

8. The method according to claim 1, characterized in that... The lime is in the form of natural hydraulic lime, prepared lime, hydraulic lime and / or air-hardening lime conforming to standard EN 459-1:2015.

9. The method according to any one of claims 1 to 3, characterized in that... The powdered polyurethane has a particle size of 0.5μm-8mm.

10. The method according to any one of claims 1 to 3, characterized in that... The powdered polyurethane has a particle size of 0.8μm-5mm.

11. The method according to any one of claims 1 to 3, characterized in that... The particle size of the powdered polyurethane is 10μm-3mm.

12. The method according to any one of claims 1 to 3, characterized in that... The particle size of the powdered polyurethane is 50 μm-1 mm.

13. The method according to any one of claims 1 to 3, characterized in that... The particle size of the powdered polyurethane is 1mm-3mm.

14. The method according to any one of claims 1 to 3, characterized in that... The volume ratio of powdered polyurethane is 2-20% by volume, relative to the total combined volume of powdered polyurethane and aggregates.

15. The method according to any one of claims 1 to 3, characterized in that... The volume ratio of powdered polyurethane is 2-10% relative to the total combined volume of powdered polyurethane and aggregates.

16. The method according to any one of claims 1 to 3, characterized in that... The volume ratio of powdered polyurethane is 3-9% relative to the total combined volume of powdered polyurethane and aggregates.

17. The method according to any one of claims 1 to 3, characterized in that... The cement-based composition is mixed with water at a water / powder weight ratio of 0.1-0.

6.

18. The method according to claim 17, characterized in that... The cement-based composition is mixed with water at a water / powder weight ratio of 0.2-0.

5.

19. The method according to claim 17, characterized in that... The cement-based composition is mixed with water at a water / powder weight ratio of 0.2-0.

35.

20. The method according to claim 1, characterized in that... In step a), mix 10-45 parts by weight of the composite hydraulic binder.

21. The method according to claim 1, characterized in that... In step a), mix 15-29 parts by weight of the composite hydraulic binder.

22. The method according to claim 1, characterized in that... In step a), mix 0.5-3 parts by weight of powdered polyurethane.

23. The method according to claim 1, characterized in that... In step a), mix 1-2 parts by weight of powdered polyurethane.

24. The method according to claim 1, characterized in that... In step a), mix 60-85 parts by weight of aggregate.

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