Cementitious composition

Abstract

The present disclosure is directed to multicomponent composition comprising: a first component comprising an inorganic binder; and, a second component comprising a hardener for said inorganic binder, wherein said composition comprises water and further comprises: a) electrically conductive filler comprising or consisting of carbon nanostructures; and, b) at least one particulate refractory compound having a particle size in the range from 35 to 500 mesh as determined in accordance with ISO 3310-1:2016 Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth.

Description

[0001] CEMENTITIOUS COMPOSITION

[0002] FIELD OF THE INVENTION

[0003] The present disclosure is directed to a cementitious composition containing electrically conductive filler. More particularly, the present disclosure is directed to a cementitious composition containing: a first component comprising an inorganic binder; a second component comprising a hardener for said inorganic binder, wherein the composition comprises water and further comprises an electrically conductive fdler which comprises or consists of carbon nanostructures.

[0004] BACKGROUND OF THE INVENTION

[0005] Cementitious materials are finding increased utility as coatings on industrial machinery, industrial installations, commercial machinery, commercial equipment and structural materials which are exposed to high temperatures, potentially concomitantly with exposure to corrosive chemicals and / or abrasive forces. The cured or set material can provide a robust composite structure which protects the underlying substrate from these harsh environmental conditions.

[0006] A number of impediments to the more expansive use of cementitious coatings in this manner have however been identified. Firstly, many industrial installations which would otherwise be candidates for such a coating have complicated shapes: pipework, chutes, hoppers, bunkers, bins and furnaces may be presented as illustrative examples of structures of complex configuration. Such complexity imposes a need for the coating to have dimensional stability. Secondly, such coating compositions must exhibit appropriate adherence to the substrate concerned. Thirdly, the compositions should demonstrate rapid strength development in casted blocks or in the applied coating: as the castable or coated structure may only be utilized after complete setting of the composition, a slow development of strength can be disadvantageous. And further, the shrinkage upon setting of a castable material or applied coating can create gaps in the casted structure, cracks or unevenness in the coating and / or mechanical stress in the coated structure.

[0007] Such cracks and unevenness in the coated structure might be visible but that is not always the case and indeed detection of such features by observation alone may not be possible based on the location of the coated structure. Visual observation may therefore be inappropriate for verifying the integrity of the coated structure both initially upon formation and over time, noting that the disposal of the coated structure under harsh working conditions - the exposure to temperature, moisture (humidity), chemical etchants and abrasive materials, for instance - may promote the cracking, erosion and delamination of the cementitious coating from the parent substrate over time. Obviously, where a coating begins to fail, the parent substrate becomes directly exposed to the working environment and thus becomes vulnerable: unchecked corrosion and / or erosion of the substrate may lead to reduced operational efficiency of the asset, an increased risk of sudden failure thereof or even an equipment break per se, causing unplanned down time and thus productivity loss.

[0008] It is conventional in industrial processing that operation conditions - such as flow rate, temperature, pressure and humidity level - are monitored, oftentimes continuously. Conversely, the art is deficient on methods of continuously monitoring the integrity of cementitious coatings. The present inventors certainly consider it unacceptable for reliance to be placed either on observation alone, on extensometer gauges disposed on the outside of coatings or on predictive maintenance and testing based upon historical data or a user’s experience with a particular cementitious coating. Certain authors in the art have shared this position but have developed solutions based on the discrete or periodic disposal of sensors within cementitious structures.

[0009] EP 3150998 Al (CSIC) describes an embedded sensor for the continuous measurement of mechanical resistance in structures made from cementitious material characterized in that it comprises: at least one magnetic microwire which is either amorphous or nanocrystalline and is embedded in a block of cementitious material, wherein the magnetic microwire is resistant to the alkaline environment of the block of cementitious material and comprises a metal core. The block of cementitious material is typically cylindrical in form and is embedded within - and may be of a distinct material from - the main structural body.

[0010] US2021190728A1 (Taha et al.) discloses a sensor for detecting damage, cracking and debonding in a cement structure comprising: a cementitious material; a plurality of periodic structures located in said cementitious material wherein said periodic structures having an acoustic stopband. The sensor has particular utility in cement structures employed in wellbores rather than for cementitious coatings.

[0011] The present inventors have resolved to develop sensory materials dedicated to the real-time, continuous monitoring of the performance of cementitious coatings so that the failure thereof can be prevented by early detection and appropriate timely measures for increasing asset life while maintaining high productivity.

[0012] STATEMENT OF THE INVENTION

[0013] In accordance with a first aspect of the disclosure there is provided a multicomponent composition comprising: a first component comprising an inorganic binder; and, a second component comprising a hardener for said inorganic binder, wherein said composition comprises water and further comprises: a) electrically conductive filler comprising or consisting of carbon nanostructures; and, b) at least one particulate refractory compound having a particle size in the range from 35 to 500 mesh as determined in accordance with ISO 3310-1:2016 Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth. In an embodiment, said first component comprises colloidal silica; and, said second component comprises at least one compound chosen from alkali metal silicates, alkaline earth metal silicates, magnesium oxide (MgO), sodium dihydrogen orthophosphate (NaHPO), sodium silica fluoride (NaSiF), sodium borate and mixtures thereof.

[0014] In another embodiment, said first component comprises an inorganic hydraulic binder; and, said second component comprises water, wherein the composition is preferably characterized by a water factor of from 0.5 to 1.5, more preferably from 0.75 to 1.25.

[0015] In this latter embodiment, it is preferred that said first component comprises calcium aluminate cement. In particular, the composition may be characterized by comprising, based on the total weight of non-volatile constituents in the composition: from 20 to 60 wt.%, preferably from 35 to 60 wt.% of said calcium aluminate cement; from 0.05 to 7.5 wt.%, preferably from 0.05 to 5 wt.% of a) said electrically conductive filler comprising or consisting of carbon nanostructures; and, from 30 to 70 wt.%, desirably from 35 to 60 wt.% of b) said at least one particulate refractory compound.

[0016] The calcium aluminate cement may desirably have a monocalcium aluminate (CA) content of least 50 wt.%, based on the total weight of the calcium aluminate cement. Independently of, or additional to this property, the calcium aluminate cement may desirably have a refractoriness of at least 1000°C.

[0017] In important embodiments of the composition, said electrically conductive filler comprises, based on the total weight of all the non-volatile constituents in the composition: from 0.05 to 5 wt.%, preferably from 0.05 to 2 wt.% of carbon nanostructures; and, from 0 to 2.5 wt.%, preferably from 0 to 2 wt.% of electrically conductive filler which is distinct from said carbon nanostructures (CNS).

[0018] Independently or, or additional to the selection of electrically conductive filler, it is preferred that the at least one refractory compound of the composition is chosen from: aluminum oxide (alumina, AI2O3); calcined bauxite; aluminium nitride; silicon oxide (SiCh); magnesium oxide (MgO); calcium oxide; zirconium oxide (zirconia, ZrO2); chromium oxide; silicon carbide (SiC); silicon nitride (SiN); tungsten carbide (WC); boron carbide (B4C); boron nitride (BN); alumina-zirconia; mullite (3A12O3-SiO2); cordierite (2MgO-2A12O3-5SiO2); fused zirconia mullite; and, mixtures thereof. For example, the at least one refractory compound may be chosen from: alumina; silica; calcined bauxite; fused zirconia mullite; silicon carbide; and, mixtures thereof.

[0019] In an embodiment of the composition, the at least one refractory compound comprises calcined bauxite, wherein said calcined bauxite preferably has a particle size in the range of from 50 mesh to 500 mesh, as determined in accordance with ISO 3310-1:2016; and, said bauxite is present in the composition in an amount of from 15 to 35 wt.%, based on the total weight of non-volatile constituents in the composition. In another embodiment of the composition, the at least one refractory compound comprises fused zirconia mullite, wherein said fused zirconia mullite preferably has a particle size smaller than 100 mesh, as determined in accordance with ISO 3310-1 :2016; and, said fused zirconia mullite is present in the composition in an amount of from 15 to 35 wt.%, based on the total weight of non-volatile constituents in the composition.

[0020] In accordance with a second aspect of the present disclosure, there is provided a cured product obtained from the composition as defined hereinabove and in the appended claims. The present disclosure further encompasses the use of the cured reaction product as defined hereinabove and in the appended claims as a coating on concrete, a refractory material or a metallic material.

[0021] In accordance with a further aspect of the disclosure, there is provided a method of monitoring an applied coating comprising: providing a coated substrate of which the coating comprises a cured product obtained from the composition as defined hereinabove and in the appended claims; and, measuring the resistivity of the coating over time.

[0022] In accordance with a still further aspect of the disclosure, there is provided a system for monitoring a coated substrate, said system comprising: i) a coated substrate of which the coating comprises a cured product obtained from the composition as defined hereinabove and in the appended claims, said coated substrate further comprising at least two spaced apart contact points; ii) at least two electrical contacts, each of the at least two electrical contacts being arranged at each of the at least two spaced apart contact points; and,

[0023] Hi) a resistance measuring device configured to measure resistance across the at least two electrical contacts.

[0024] The cementitious coating obtained from the present composition provides for the monitoring of cracking, corrosion, erosion, distortion and delamination of the cementitious coating. The initial coating presents a conductive path having an initial resistivity, as determinable by resistance measurements taken on the surface of the coating. Small structural changes in the coating will yield commensurate changes in resistivity. Further, the development of cracks in the cementitious coating will damage the conductive paths, significantly increasing resistivity.

[0025] As the monitoring method does not require the implantation or addition of sensors into the coating material, it presents at least the following advantages: the embedding of sensors and resulting performance degradation of the coating can be avoided; monitoring can be performed accurately and with timeliness; and, the measurement method is stable and durable.

[0026] Where the aspects of the disclosure are described above as having certain embodiments, any one or more of those embodiments can be implemented in or combined with any one of the further embodiments, even if that combination is not explicitly described. Expressed differently, the described embodiments are not mutually exclusive, and permutations thereof remain within the scope of this disclosure.

[0027] DEFINITIONS

[0028] As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise.

[0029] The terms "comprising", "comprises" and "comprised of’ as used herein are synonymous with "including", “includes”, “containing ’ or “contains”, and are inclusive or open-ended and do not exclude additional, nonrecited members, elements or method steps.

[0030] As used herein, the term “consisting o excludes any element, ingredient, member or method step not specified. For completeness, the term “comprising ’ encompasses “consisting of.

[0031] The words "preferred' , "preferably" , “desirably” and “particularly” are used frequently herein to refer to embodiments of the disclosure that may afford particular benefits, under certain circumstances. However, the recitation of one or more preferable, preferred, desirable or particular embodiments does not imply that other embodiments are not useful and is not intended to exclude those other embodiments from the scope of the disclosure.

[0032] The word “exemplary” is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word exemplary is intended to present concepts in a concrete fashion.

[0033] As used throughout this application, the word “may” is used in a permissive sense - that is meaning to have the potential to - rather than in the mandatory sense.

[0034] The term “plurality” as used herein is defined as two or more than two.

[0035] When amounts, concentrations, dimensions and other parameters are expressed in the form of a range, a preferable range, an upper limit value, a lower limit value or preferable upper and limit values, it should be understood that any ranges obtainable by combining any upper limit or preferable value with any lower limit or preferable value are also specifically disclosed, irrespective of whether the obtained ranges are clearly mentioned in the context.

[0036] Further, in accordance with standard understanding, a weight range represented as being “from 0 to x” specifically includes 0 wt.%: the ingredient or part - a) or b) herein, for example - defined by said range may be absent from the material or may be present in the material in an amount up to x wt.%.

[0037] As used herein, room temperature is 23°C plus or minus 2°C. As used herein, “ambient conditions” means the temperature and pressure of the surroundings in which the composition is located or in which a coating layer or the substrate of said coating layer is located.

[0038] Multi-component compositions” in the context of the present disclosure are understood to be compositions in which at least a first component (A) and a second component (B) must be prepared and stored separately because of their (high) reactivity. The at least two components are mixed only shortly before or during application and then react, optionally under additional activation such as heating or irradiation.

[0039] The present compositions are defined herein as being “substantially free” of certain compounds, elements, ions or other like components. The term “substantially free” is intended to mean that the compound, element, ion or other like component is not deliberately added to the composition and is present, at most, in only trace amounts which will have no (adverse) affect on the desired properties of the coating. An exemplary trace amount is less than 1000 ppm by weight of the composition. The term “substantially free” encompasses those embodiments where the specified compound, element, ion, or other like component is completely absent from the composition or is not present in any amount measurable by techniques generally used in the art.

[0040] The term “anhydrous” is intended to equate to substantially free of water and thereby also encompasses those embodiments where water is completely absent from the composition or is not present in any amount measurable by techniques generally used in the art.

[0041] As used herein, the term “water” is intended to encompass tap water, spring water, purified water, de-ionized water, de-mineralized and distilled water. Water is included in the compositions of the present disclosure in its liquid form. The presence of solid water particles - ice - is not desirable as solid water cannot be mobilized for the formation of the hydrates required for the development of strength in cured composition.

[0042] The aforementioned composition has been defined by “wt. % based on the total weight of all the non-volatile constituents in the composition” . For completeness, a volatile constituent is a constituent which has an initial boiling point of less than or equal to 250°C as measured at a standard atmospheric pressure of 101.3 kPa. A nonvolatile constituent is therefore a constituent which has an initial boiling point of more than 250°C as measured at a standard atmospheric pressure of 101.3 kPa. The term "electrically conductive filler” refers herein to particulate fillers which are characterized by a bulk resistivity - as determined according to ASTM D257 - of less than 50 pQ-cm, preferably less than 30 pQ-cm and more preferably less than 10 pQ-cm. The bulk resistivity is an inherent property of the material which is independent of the size and shape thereof.

[0043] The term "carbon nanolube" as used herein refers to carbon fullerene, a synthetic graphite, which typically has a molecular weight of greater than 840 g / mole. The term is intended to encompass roped carbon nanotubes, single-walled carbon nanotubes (SWCNT) and multiple walled carbon nanotubes (MWCNT). Single walled carbon nanotubes - having a wall consisting of only one graphene layer - typically have diameters of from 1 to 5 nm; multi-walled carbon nanotubes typically have diameters of from 5 to 200 nm. It is further envisaged that carbon nanotubes having utility herein may be opened or chopped, for which US Patent No. 7,641,829 B2 provides an instructive reference. And still further, the present disclosure does not preclude the use of carbon nanotubes which have been chemically modified through, for example, doping with thionyl chloride (SOCh).

[0044] By a "refractory material", to which the composition of the present disclosure may be applied, is meant a material having a melting point above 1500°C. This definition encompasses: refractory materials which are elements, such as graphite, boron, silicon, titanium, hafnium, zirconium, molybdenum, niobium, tantalum and tungsten; and, refractory materials which are compounds, said compounds typically being silicides, oxides, borides or carbides. Examples of refractory compounds include: aluminum oxide; aluminium nitride; silicon oxide; magnesium oxide; calcium oxide; zirconium oxide; titanium oxide; chromium oxide; silicon carbide; silicon nitride; boron carbide; boron nitride; tungsten diboride; tungsten carbide; tantalum carbide; and, combinations thereof. The term "refractory material" is further intended to encompass both monolithic materials and shaped materials. And there is no particular intention to limit the shape of such refractory materials: illustrative shapes include ceramic fibers, blocks, bricks, wedges, tiles and plates but more complex geometries are equally envisaged.

[0045] As used herein, “refractoriness” is measured under load in accordance with ISO 1893. A cylindrical test piece of the material to be analyzed is used, which test piece has: a diameter of 50 mm; a height of 50 mm; and, a coaxial bore of 12.5 mm in diameter. A constant load (kg) is applied thereto and the test piece is subjected to increasing temperature. The recorded refractoriness temperature herein is the minimum temperature at which softening occurs as observed by the deformation of the test piece.

[0046] As used herein, the term "metallic material" means a pure metal, a metal alloy or a metal composite. As exemplary metals and metallic alloys to which the compositions of the present disclosure may be applied, mention may be made of: aluminum; aluminum alloys; bronze; beryllium; beryllium alloys; chromium; chromium alloys; cobalt; cobalt alloys; copper; copper alloys; gold; iron; iron alloys; steels; magnesium; magnesium alloys; nickel; nickel alloys; lead; lead alloys; tin; tin alloys, such as tin-bismuth and tin-lead; zinc; zinc alloys; and, superalloys, such as International Nickel 100 (IN-100) or International Nickel 718 (IN-718). Representative steels include: crucible steel; carbon steel; spring steel; alloy steel; maraging steel; and, stainless steel, inclusive of austenite stainless steel, ferritic stainless steel, duplex stainless steel, and Martensitic stainless steel. And again there is no particular intention to limit the shape of such metallic materials: the complex geometries of pipes, elbows, hoppers, bins, chutes, furnaces and the like found in industrial installations are certainly envisaged.

[0047] As used herein, the term “ alloy” refers to a substance composed of two or more metals or of a metal and a non- metal which have been intimately united, usually by being fused together and dissolved in each other when molten.

[0048] The term “binder” is to be understood as any component having the property of introducing cohesion to the composition in which it is incorporated and which makes it possible to provide mechanical characteristics to the said formulation, such as but not limited to compressive strength, tensile strength and adherence.

[0049] The term “hydraulic binder” is to be understood as any binder ingredient which has the property of becoming hydrated in the presence of water, the hydration of which ingredient makes it possible to obtain a solid having mechanical characteristics. The term “hydraulic binder” also denotes hydric binders.

[0050] As used herein, “concrete” means any type of building material containing aggregates such as stone, gravel, brushed rock or sand which are embedded in a matrix - cement or binder - that fdls the space between the aggregate particles and binds them together. Exemplary matrices include Portland Cement, mineral mortar, asphalt and polymer resins. The “concrete” may further include organic or silica-based fibers or metallic wires, cables or rods as reinforcing materials.

[0051] For completeness, the term “water factor” is used herein to denote the weight of water used in a composition divided by the total weight of used non-volatile components (w / w).

[0052] As used herein, “curing” refers to the reactions through which a given composition hardens from a fluid mixture into a solid. Broadly, curing may be performed herein by exposure to ambient conditions or by deliberate exposure to moisture, heat or radiation.

[0053] Unless otherwise stated, the term “particle size” refers to the largest axis of the particle. In the case of a generally spherical particle, the largest axis is the diameter.

[0054] The term “mean particle size” (Dv50f as used herein, refers to a particle size corresponding to 50% of the volume of the sampled particles being greater than and 50% of the volume of the sampled particles being smaller than the recited Dv50 value. Similarly, if used, the term “Dv90” refers to a particle size corresponding to 90% of the volume of the sampled particles being smaller than and 10% of the volume of the sampled particles being greater than the recited Dv90 value.

[0055] The term “colloidal dispersion" as used herein refers to a system in which particles of colloidal size - which have a particle size of from 1 nm to 1 pm, as determined by dynamic light scattering - are dispersed in a continuous phase of a different composition.

[0056] The term “colloidal silica" as used herein refers to silica in colloidal form in an aqueous continuous phase, which aqueous phase may comprise water and, optionally, dispersants such as surfactants. Conventionally the particulate silica will have a mean particle size (Dv50) of from 1 to 1000 nm, for example from 1 to 150 nm, as determined by dynamic light scattering. The colloidal silica may be prepared by passing sodium silicate through a bed of cation-exchange resin in the hydrogen form.

[0057] Viscosities of the compositions described herein are, unless otherwise stipulated, measured using the Brookfield Viscometer at standard conditions of 20°C and 50% Relative Humidity (RH). The method of calibration, the spindle type and rotation speed of the Brookfield Viscometer are chosen according to the instructions of the manufacturer as appropriate for the composition to be measured.

[0058] DETAILED DESCRIPTION OF THE INVENTION

[0059] The composition of the present disclosure comprises: a first component comprising an inorganic binder; and, a second component comprising a hardener for said inorganic binder, wherein said composition comprises water and further comprises: a) electrically conductive filler comprising or consisting of carbon nanostructures; and, b) at least one particulate refractory compound having a particle size in the range from 35 to 500 mesh as determined in accordance with ISO 3310-1:2016 Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth.

[0060] As noted, the composition of the present disclosure comprises water. In certain embodiments, water may constitute the hardener for a hydraulic inorganic binder and, as such, the first component may be formulated as an anhydrous composition to which a second component comprising or consisting of water is added. In other embodiments, water may be used as carrier for the inorganic binder in the first component, as a carrier for the hardener of the second component or as a carrier for both of said binder and hardener in the first and second components respectively, where said binder and / or hardener of the composition are inert to water.

[0061] The method by which the composition is to be applied is one determinant of the total amount of water added and the time at which any water is admixed with the ingredients relative to the application of the composition. However, a further determining consideration is that the addition of too much water to the composition may result in particulate materials falling out of suspension, which materials can be difficult to re-suspend. Generally, a water factor of from 0.5 to 1.5, for example a water factor of from 0.75 to 1.25, may be mentioned as being suitable in preparing the present composition. Independently of or additional to the preferred water factor, it is preferred that the composition be characterized by a viscosity at application of less than 100000 centipoise, for example from 10000 to 100000 centipoise. a) Electrically Conductive Filler

[0062] The composition of the present disclosure comprises a) electrically conductive fdler, wherein said electrically conductive fdler comprises or consists of carbon nanostructures. It is preferred that the composition comprises from 0.05 to 7.5 wt.%, preferably from 0.05 to 5 wt.% of b) electrically conductive fdler, based on the total weight of all the non-volatile constituents in the composition.

[0063] The amount and disposal of the electrically conductive filler in the composition should serve to form semi- continuous or continuous conductive pathways which extend through the body of the cured composition. These pathways should thereby provide a low resistance route by which electrons and, in some instances thermal phonons, can travel through the cured composition. It is preferred for the cured composition to be electrically conductive in all three dimensions and thus across its width, length and thickness. As is known in the art, electrical resistance measurements may be taken on a surface of the material using a probe, such as a 4-point probe, connected to an ohmmeter.

[0064] The necessary formation of these conductive pathways should be determinative of the loading of the filler within the composition. In addition, the loading of the filler may be selected to attain an operable density and operable rheological and adhesive properties of the composition.

[0065] The electrically conductive filler may be disposed in either the first component, the second component or both of said first and second components. Further, the distribution of the electrically conductive filler within the composition may be homogeneous or non-homogeneous, the latter possibility reflecting that it may be beneficial in certain circumstances for the concentration of particulate filler to vary across a dimension, in the particular the thickness, of the cured composition. Such variation may permit specific loci of the cured composition to exhibit higher relative electrical conductivity and, potentially, thermal conductivity. Such variation should not however compromise the structural integrity of the cured material by, for instance, reducing the hardness, tensile strength or impact resistance thereof. a) i) Carbon Nanostructure

[0066] Carbon nanostructures are necessarily included in the present composition as at least a part of the conductive filler. For completeness, this does not preclude the conductive filler consisting essentially or consisting of said carbon nanostructures. It is preferred that the composition comprises from 0.05 to 5 wt.%, for example from 0.05 to 2 wt.%, from 0.05 to 1 wt.% or from 0.05 to 0.5 wt.% of carbon nanostructures, based on the total weight of all the non-volatile constituents in the composition. At the aforementioned levels of the carbon nanostructure, the composition - when cured - can exhibit efficacious electrical conductivity without having compromised adhesive and mechanical properties.

[0067] The term "carbon nanostructure” or “CNS” refers herein to a plurality of carbon nanotubes (CNTs) that can exist as a polymeric structure through, in particular, sharing common walls with one another and / or through being one or more of: interdigitated; branched; entangled; or, crosslinked. Thus, carbon nanostructures can be considered to have carbon nanotubes as a base monomer unit of their polymeric structure. In many cases, the constituent carbon nanotubes will be multiple walled carbon nanotubes (MWCNT).

[0068] Typically carbon nanostructures are grown on a substrate, such as a fiber material, under CNS growth conditions. In such cases, at least a portion of the carbon nanotubes of the carbon nanostructure can be aligned substantially parallel to one another, much like the parallel CNT alignment seen in conventional carbon nanotube forests.

[0069] In important embodiments of the present disclosure, the electrically conductive carbon nanostructure (CNS) is selected from the group consisting of: carbon nanostructures or fragments of carbon nanostructures which include a plurality of multiple walled carbon nanotubes that are crosslinked into a polymeric structure through sharing common walls with one another and / or through being one or more of interdigitated, branched, entangled or crosslinked; fractured carbon nanotubes derived from the carbon nanostructures and branched and sharing common walls with one another; elongated CNS strands derived from the carbon nanostructures and including carbon nanotubes that have been displaced linearly with respect to one another; dispersed CNS comprising exfoliated fractured carbon nanotubes hat do not share common walls with one another; and, combinations thereof. a) ii) Further Electrically Conductive Filler

[0070] It is not precluded that part a) of the present composition may comprise a)ii) electrically conductive filler which is distinct from said carbon nanostructure (CNS). The composition may comprise from 0 to 2.5 wt.%, for example up to 2 wt.% of a)ii) said electrically conductive fdler, based on the total weight of all the non-volatile constituents in the composition. The electrically conductive fdler a)ii) should be characterized by a bulk resistivity of less than 50 microohm-centimeters (pQ-cm).

[0071] There is no particular intention to limit the shape of the particles which may be employed as the conductive fdler a)ii): particles that are fibrous, acicular, spherical, ellipsoidal, cylindrical, bead-like, cubic or platelet-like may be used alone or in combination. Moreover, it is envisaged that agglomerates of more than one particle type may be used. There is furthermore no particular intention to limit the size of the particles employed as conductive filler. However, such conductive filler will conventionally have a mean particle size by volume (Dv50), as measured by laser diffraction / scattering methods, of from 0.1 to 1500 pm, for example from 1 to 1250 pm.

[0072] Exemplary conductive particulate fillers include, but are not limited to: aluminum; silver; copper; nickel; silver- coated nickel; silver coated copper; silver coated aluminum; carbon black; carbon fiber; graphene; graphite; silver coated graphite; indium tin oxide; metallic coated glass spheres; metallic coated filler; metallic coated polymers; silver coated fiber; silver coated spheres; antimony doped tin oxide; conductive nanospheres; nano silver; nano aluminum; nano copper; nano nickel; and, mixtures thereof.

[0073] The use of a conductive filler comprising or consisting of carbon black may be mentioned in particular. Said carbon blacks should desirably be characterized by: a specific surface area of from 20 to 2000 m2 / g, preferably from 250 to 1500 m2 / g, as determined by low temperature nitrogen absorption in accordance with ASTM D 3037-78; a pore volume of from 1 to 4 ml / g as determined by mercury porosimetry; and, a pore diameter of from 25 to 1000 Angstroms, as determined by mercury porosimetry.

[0074] Exemplary commercial conductive carbon blacks which may have utility herein include: Black Pearls 2000®, Vulcan® XC-72, Vulcan®3C and Vulcan® C available from Cabot Corporation; and; Ketjenblack®, available from Noury on. b) Particulate Refractory Compounds

[0075] The composition of the present disclosure further comprises at least one particulate refractory compound having a particle size in the range from 35 to 500 mesh as determined in accordance with ISO 3310-1 :2016 Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth. The particulate refractory compound(s) may be disposed in either the first component, the second component or both of said first and second components. That aside, it is preferred that the composition comprises, based on the total weight of nonvolatile constituents in the composition, from 30 to 70 wt.%, desirably from 35 to 60 wt.% of said at least one particulate refractory compound.

[0076] There is no particular intention to limit the shape of the particles which may be employed as part b) of the composition: particles that are fibrous, acicular, spherical, ellipsoidal, cylindrical, bead-like, cubic or plateletlike may be used alone or in combination. It is however preferred that the employed particulate is an agglomerated particle which can thereby impart the property of abrasiveness to that employed particulate. Whilst the present disclosure does not preclude the use of shaped or molded abrasive particles of the refractory compounds, the employed particulate refractory compounds should typically comprise or consist of crushed abrasive particles by which meant particles that are formed through a mechanical fracturing process.

[0077] Without intention to limit the present disclosure, the refractory compound of part b) of the composition may be selected from the group consisting of: aluminum oxide (alumina, AI2O3); calcined bauxite; aluminium nitride; silicon oxide (SiCh); magnesium oxide (MgO); calcium oxide; zirconium oxide (zirconia, ZrCh); chromium oxide; silicon carbide (SiC); silicon nitride (SiN); tungsten carbide (WC); boron carbide (B4C); boron nitride (BN); alumina-zirconia; mullite (SAUOs-SiCh); cordierite (2MgO-2A12O3-5SiC>2); fused zirconia mullite; and, combinations thereof. In an embodiment, part b) of the composition may comprise one or more of alumina, silica, calcined bauxite, fused zirconia mullite and silicon carbide. b) i) Calcined Bauxite

[0078] The composition may comprise calcined bauxite. It is preferred that the composition comprises, based on the total weight of non-volatile constituents in the composition, from 0 to 35 wt.%, for example from 10 to 35 wt.% or from 20 to 35 wt.% of said calcined bauxite. The composition may, for example, comprise from 20 to 30 wt.% of said calcined bauxite.

[0079] Bauxite itself is an impure form of alumina containing other oxides including, for example, iron oxide, titania and silica. As is known in the art, calcined bauxite is produced by sintering superior grade or high-alumina bauxite - typically in rotary, round or shaft kilns - at high temperatures, for instance from 800°C to 1600°C. This process of calcining the bauxite removes moisture therefrom and gives calcined bauxite its characteristic high alumina content and refractoriness, low iron content, and grain hardness and toughness.

[0080] Without intending to limit the present disclosure, the calcined bauxite may be characterized by having, based on the weight of the calcined bauxite: i) an alumina content of at least 82 wt.% and preferably at least 83 wt.%; ii) a silica ( Si O2) content of less than 5 wt.%; Hi) a titanium dioxide content of less than 4.5 wt.%; and, iv) an FC2O3 content of less than 4.5 wt.%. The calcined bauxite may be further characterized by a Loss on Ignition of less than 0.5 wt.%, as determined in accordance with ASTM Cl 14 Standard test methods for chemical analysis of hydraulic cement.

[0081] Independently or additionally to this compositional requirement, it is herein preferred that the particle size of the calcined bauxite is smaller than 35 mesh and is preferably in the range of from 50 mesh to 500 mesh, for example from 65 to 325 mesh, as determined in accordance with ISO SSlO-l^OlbTestWves- — Technical requirements and testing — Parti: Test sieves of metal wire cloth. b) ii) Fused Zirconia Mullite The composition may comprise fused zirconia mullite. It is preferred that the composition comprises, based on the total weight of non-volatile constituents in the composition, from 0 to 35 wt.%, for example from 10 to 35 wt.% or from 20 to 35 wt.% of said fused zirconia mullite. The composition may, for example, comprise from 20 to 30 wt.% of said fused zirconia mullite.

[0082] As is known in the art, mullite AFOs^SiCh) is an orthorhombic homogeneous solid solution of alumina in sillimanite and can be made by heating andalusite, sillimanite or kyanite. Fused zirconia mullite can be prepared by blending a pre-determined proportion of zirconia with mullite and heating the blend to a temperature sufficient to melt the blend followed by cooling to form a solidified mass. The solidified mass is then crushed to produce a particulate form of the fused zirconia mullite. It is believed that the zirconia is substantially dispersed in the form of rods and / or nodules in the mullite and this imparts thermal shock resistance and chemical resistance to the material.

[0083] It is preferred herein that the fused zirconia mullite used herein comprises, based on the weight of the fused zirconia mullite: from 25 to 45 wt.%, for example from 30 to 45 wt.% of zirconia; and, from 55 to 75 wt.%, for example from 55 to 70 wt.% of mullite. An amount of zirconia below 25 wt.% would be insufficient to impart effective chemical and thermal shock resistance to the obtained coating while it is considered that an amount above 45 wt.% would impart brittleness to that material.

[0084] Independently or additionally to this compositional requirement, it is herein preferred that the particle size of the fused zirconia mullite is smaller than 100 mesh and is preferably in the range of from 120 mesh to 500 mesh, as determined in accordance with ISO 3310-1 '.IQ Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth. b) iii) Silicon Carbide

[0085] The composition may further comprise silicon carbide: as such that composition may be further characterized by comprising, based on the total weight of non-volatile constituents in the composition, from 0 to 20 wt.% of said silicon carbide. It is preferred that the composition comprises, based on the total weight of non-volatile constituents in the composition, from 5 to 20 wt.%, preferably from 15 to 15 wt.% of said silicon carbide.

[0086] It is noted that either the alpha (a-) or the beta (P-) silicon carbide polymorphs independently or mixtures of said polymorphs can be employed in the present composition. However, the P-silicon carbide polymorph has relatively poor oxidation resistance compared to the alpha (a-) form. Thus, the alpha (a-) polymorph is generally preferred over the beta (P-) polymorph for that reason and, conveniently, is typically of lower cost commercially. In a further statement of preference, which is not intended to be mutually exclusive of the polymorphic form, it is preferred that said silicon carbide has a minimum SiC content - as equated with purity - of 98 wt.%, and more preferably a minimum SiC content of 99 wt.%

[0087] Independently or additionally to the stated compositional preferences, it is herein preferred that the particle size of the silicon carbide is smaller than 100 mesh and is preferably in the range of from 200 mesh to 500 mesh, as determined in accordance with ISO 3310- 1 :2016 / Cs / .s / Vvtss — Technical requirements and testing — Part 1: Test sieves of metal wire cloth.

[0088] It is considered that a mixture of silicon carbide grains having different average particle sizes may be utilized in the present disclosure. This can facilitate particle packing, thereby reducing porosity and increasing the abrasion resistance of the cured composition. However, none of the silicon carbide grains included in the composition should exceed 0.5 mm in size (35 mesh . if such larger grain is present, it will tend to settle out of a raw composition batch and lead to a product which is not homogeneous, especially if the vehicle content of the raw batch is toward the high end of its stated range.

[0089] Binder Systems

[0090] The composition of this disclosure comprises: a first component comprising an inorganic binder; and, a second component comprising a hardener for said inorganic binder, which components together constitute the binder system of the composition. There is no particular intention to limit the binder system but two important embodiments of such a system may be mentioned.

[0091] BS.l First Exemplary Binder System Embodiment

[0092] In a first exemplary embodiment, said first component of the composition comprises an inorganic hydraulic binder; and, said second component comprises water, wherein the composition is preferably characterized by a water factor of from 0.5 to 1.5, more preferably from 0.75 to 1.25. It is preferred that the composition comprises, based on the total weight of non-volatile constituents in the composition, from 20 to 60 wt.%, preferably from 35 to 60 wt.% of said inorganic hydraulic binder.

[0093] Exemplary inorganic hydraulic binders, which may be used alone or in combination include, but are not limited to: cement(s); mineral additions; anhydrous calcium sulphate; and, semi-hydrated calcium sulphate.

[0094] The term “cement” is understood to mean a cement according to EN 197-1 (2001) and, in particular, a CEM I, CEM II, CEM III, CEM IV or CEM V type cement according to Cement NF EN 197-1 (2012). The use of more than one different cement in or as the inorganic hydraulic binder is not precluded. The term "mineral additions” refers to: slags, as defined in Cement Standard EN 197-1 (2012) section 5.2.2; steelmaking slags; pozzolanic materials, as defined in Cement Standard EN 197-1 (2012) section 5.2.3;, fly ash, as defined in Cement Standard EN 197-1 (2012) section 5.2.4; calcined schists, as defined in Cement Standard EN 197-1 (2012) section 5.2.5; limescale, as defined in Cement Standard EN 197-1 (2012) section 5.2.6; fumed silica, as defined in Cement Standard EN 197-1 (2012) section 5.2.7; or, their mixtures. Further mineral additions, not currently recognized by the Cement Standard EN 197-1 (2012), may also have utility in or as the inorganic hydraulic binder. These include, in particular: metakaolins, such as type A metakaolins conforming to standard Norme Francaise (NF) P 18-513 (August 2012); and, siliceous additions, such as the siliceous additions conforming to standard Norme Francaise (NF) P 18-509 (September 2012).

[0095] BS.1.1 Calcium Aluminate Cement

[0096] In an important example, the inorganic hydraulic binder of the present disclosure comprises calcium aluminate cement. When used, it is preferred that the composition comprises, based on the total weight of non-volatile constituents in the composition, from 20 to 60 wt.%, preferably from 35 to 60 wt.% of said calcium aluminate cement.

[0097] As used herein, the term “calcium aluminate cement” refers to cements in accordance with Standard EN 14647 Calcium Aluminate Cement: Composition, specifications and conformity criteria. Such cements may be produced by smelting or sintering as is known in the art and within this Standard can be categorized into the groups: rich in iron; and, low in iron. So-called iron-free calcium aluminate cements are not included in the definition of EN 14647.

[0098] Typical calcium aluminate cements that are rich in iron are produced by means of the smelting process, have a grey to black-grey colour and can be characterized by their chemical composition by weight as follows: 36-42% AI2O3; 2-6% SiCE; 14-19% Fe20s; 37-40% CaO; less than 1.5% MgO; and less than 0.4% SO3. Calcium aluminate cements that are low in iron are coloured beige to grey and typically contain by weight: 50-55% AI2O3, 2-6% SiC>2, 1-3% Fe2C>3, 37-40% CaO and less than 1.5% MgO as well as less than 0.4% SO3. It is therefore evident that the colour of calcium aluminate cements becomes darker the higher their iron content.

[0099] When manufacturing calcium aluminate cements, the following mineral phases form, depending on the selected ratio of aluminium oxide (A) to calcium oxide (C): i) in calcium aluminate cement with a high iron content: monocalcium aluminate (CA), brown millerite (C4AF), belite (C2S), gehlenite (C2AS), mayenite (C12A7) and perovskite (CT); and, ii) in calcium aluminate cement types with a low iron content, CA, C2AS, CT and C12A7.

[0100] The monocalcium aluminate phase (CA) is mainly responsible for desirable hydraulic properties of the calcium aluminate cements, in particular their early strength development as compared to calcium silicate type cements. It is considered that the phases CA and, if included, C12A7, are the only phases in calcium aluminate cements that react quickly with water. However, whilst it may be stated that the reactivity of calcium aluminates with water increases with an increase in the C / A molar ratio term, an excessively high C12A7 content can promote the premature setting of the calcium aluminate cement on account of its high hydraulic reactivity.

[0101] In a preferred embodiment, the calcium aluminate cement for use in the present disclosure is characterized by an aluminum oxide content of from 30 to 55 wt.%, preferably 35 to 45 wt.%, based on the total weight of the calcium aluminate cement.

[0102] In another embodiment, the calcium aluminate cement for use in the present disclosure has monocalcium aluminate (CA) as main mineral phase, by which is means that said monocalcium aluminate (CA) is the biggest fraction of all present mineral phases in the calcium aluminate cement. The calcium aluminate content may, for instance, be at least 50 wt.% or at least 55 wt.%, based on the total weight of the calcium aluminate cement.

[0103] In a still further embodiment, which is not intended to be mutually exclusive of those embodiments mentioned above, the calcium aluminate cements for use in the present disclosure has a refractoriness of at least 1000°C, preferably at least 1200°C.

[0104] Without intention to limit the present disclosure, exemplary commercially available calcium aluminate cements having utility herein include: Istra™ 40 and Istra™ 50 available from Calucem; Ciment Fondu and Secar™ 51 available from Kemeos; Electroland available from Cementos Molins; and, Gorkal™ 40 and Gorkal™ 50 available from Gorka.

[0105] BS.2 Colloidal Silica Binder System

[0106] In a second exemplary embodiment of the binder system of multicomponent composition: the first component comprises colloidal silica; and, the second component comprises a hardener for said colloidal silica. It is preferred that the composition comprises, based on the total weight of non-volatile constituents in the composition, from 10 to 40 wt.%, preferably from 10 to 30 wt.% of the total weight of said colloidal silica and said hardener for said colloidal silica.

[0107] It is preferred that the silica particles of the colloidal silica have a mean particle size (Dv50) of from 10 to 250 nm, for example from 10 to 150 nm or from 20 to 100 nm, as determined by dynamic light scattering. Independently of, or additional to this characterization, the colloidal silica of the first component may comprise from 10 to 50 wt.%, for example from 10 to 40 wt.% or from 20 to 40 wt.% of silica, based on the weight of the colloidal silica.

[0108] It is not precluded that the silica particles of colloidal silica may have been subjected to surface modification to enhance their dispersion stability. Exemplary modifying compounds, which serve to introduce hydroxyl groups at the surface of such modified silica include, but are not limited to, silanol compounds, silandiol compounds and vicinal polyols.

[0109] Exemplary commercial colloidal silicas having utility in this embodiment include: BINDZIL™ 401 / 170, BINDZIL™ 40 / 220 or BINDZIL™ CC401, available from Nouryon; and, AREMCO Ccrambmd ™ 644s, available from Aremco.

[0110] In this exemplary embodiment, the hardener of the second component may, in certain embodiments, comprise at least one basic silicate salt, which salt is preferably chosen from ammonium silicate, potassium silicate, sodium silicate, calcium silicate, magnesium silicate and mixtures thereof. The use of potassium silicate may be mentioned in particular.

[0111] The hardener of the second component may alternatively or additionally comprise a crosslinker. Such crosslinkers may act to reduce the pH of or remove negatively individual particles from the colloidal silica upon admixture therewith. In certain instances, crosslinking may require the application of heat to the admixture.

[0112] Exemplary crosslinkers, which may be used alone or in combination include: magnesium oxide (MgO); sodium dihydrogen orthophosphate (NfeHPCL); sodium silica fluoride (NaSiFe ); and, sodium borate.

[0113] Adjuvants

[0114] The term “adjuvant” as used herein denotes a substance within the meaning of standard EN 206.1, and specifically the definition in paragraph 3.1.22 thereof: a product added to the composition in small amounts relative to the mass of composition in order to modify the properties of the fresh or cured composition. Such adjuvants can be used in such combination and proportions as desired, provided they do not adversely affect the nature and essential properties of the composition. While exceptions may exist in some cases, the composition should not comprise in toto more than 20 wt.%, based on the total weight of non-volatile constituents in the composition, of adjuvants and preferably should not comprise more than 10 wt.% of said adjuvants.

[0115] For completeness, it is noted that, in general, adjuvants which are reactive may either be provided as a separate component of the composition or may be blended into that one of the first and second components which is appropriate to ensure the storage stability thereof. Unreactive materials may be formulated into any component.

[0116] The composition may comprise at least one adjuvant chosen from: colloidal dispersions of alumina and / or titania; plasticizers; superplasticizers; setting retarders, such as gluconates, carboxylic acids (citric acid, tartaric acid), boric acid, sodium tetraborate decahydrate (Borax) and alkali metal phosphates; catalysts; setting accelerators, such as nitrate, thiocyanate and chloride salts; curing accelerators, such as alkali metal carbonates; air entrainers, such as sodium lauryl sulfates; anti-shrinkage agents; anti-bubbling or antifoam agents; leak- proofing agents such as calcium stearate; natural pozzolanic compounds, such as pumice, trass, santorin earth, kieselguhr, hornstone and chert; synthetic pozzolanic compounds, such as fired, ground clay (ground brick), fly ashes, silica dust, oil shale ash and metakaolin; anti-sedimentation agents, such as bentonites and attapulgites; mineral or organic pigments; a latex or latices; rheology modifiers; and, water retainers, such as starch ethers, cellulose ethers and modified cellulose ethers.

[0117] Whilst larger silica particles may be included in part b) of the composition, this does not preclude the composition from comprising non-colloidal silica particles having a particle size of less than 1pm, for example 0.05 to 0.5 microns. When present, such sub-micron silica particles may preferably constitute from 1 to 15 wt.%, for example from 1 to 10 wt.% of the total weight of non-volatile constituents in the composition.

[0118] Where sub-micron, non-colloidal silica is so-incorporated, the silica may be amorphous, crystalline or fumed. It is however preferred that said sub-micron silica should comprise or consist of fumed silica and more preferably fumed silica having a surface area of from 30 to 400 m2 / g, as determined by the Brunauer, Emmet and Teller (BET) method.

[0119] As is known in the art, a “superplasticizer” denotes a de-flocculant organic compound, which acts by electrostatic repulsion and / or by steric bulk. Exemplary superplasticizers having utility in the present disclosure include but are not limited to: polycarboxylates; melamine sulfonates; and, polynaphthalene sulfonates.

[0120] The inclusion of organic homo-polymers and co-polymers in the composition is not precluded: a latex or latices of such polymers can moderate the adhesive and physical properties of the composition and any coatings obtained there from. Non-limiting examples of suitable (co-)polymers include: vinyl acetate homopolymers; copolymers of vinyl acetate with at least one further vinyl ester; copolymers of vinyl acetate with ethylene; copolymers of vinyl acetate, ethylene and at least one further vinyl ester; copolymers of vinyl acetate, ethylene and at least one (meth) acrylic ester; copolymers of vinyl acetate with (meth)acrylates and other vinyl esters; copolymers of vinyl acetate, ethylene and vinyl chloride; copolymers of vinyl acetate, ethylene and styrene; copolymers of vinyl acetate with acrylates; styrene-acrylic ester copolymers; styrene- 1,3 -butadiene copolymers; and, vinyl chloride -ethylene copolymers.

[0121] Preference is given to: vinyl acetate homopolymers; copolymers of vinyl acetate with ethylene; copolymers of vinyl acetate, ethylene and styrene; copolymers of vinyl acetate, ethylene and at least one co-monomer selected from the group consisting of vinyl esters having from 1 to 15 carbon atoms in the carboxylic acid radical, such as vinyl propionate, vinyl laurate and vinyl versatate; copolymers of vinyl acetate, ethylene and at least one comonomer selected from (meth) acrylic esters of unbranched or branched alcohols having from 1 to 15 carbon atoms, such as N-butyl acrylate and 2-ethylhexyl acrylate; copolymers of vinyl acetate, vinyl esters having from 1 to 15 carbon atoms in the carboxylic acid radical and (meth) acrylic esters of unbranched or branched alcohols having from 1 to 15 carbon atoms; and, copolymers of vinyl acetate, ethylene and vinyl chloride. Such polymers may be prepared by conventional means accessible to the skilled artisan, such as by emulsion polymerization. In the alternative, such polymers may be provided from commercial sources. By way of example, reference may be made to: FX7000 styrene acrylate copolymer, available from Elotex; HD 1500 vinyl acetate / vinyl versatate copolymer, available from Elotex; and, and FX2322 vinyl acetate / ethylene copolymer available from Elotex.

[0122] The term "rheology modifier" denotes an organic compound having utility in increasing one or more of the viscosity, the cohesion and the shear threshold of the composition. Rheology modifiers may further have an antibleeding effect. As exemplary rheology modifiers having utility in the present disclosure, mention may be made of modified or unmodified polysaccharides such as diutan gums, xanthan gums, gellan gums and welan gums.

[0123] METHODS AND APPLICATIONS

[0124] To form the described compositions, the non-volatile ingredients as defined herein above are admixed in the presence of water and in such a manner that the reactive first and second components are brought together. High intensity mixing - in which a mixing energy of at least 0.5 kW per 100 kg of ingredients is used - is preferred to ensure that a homogeneous mixture is obtained. The use of a flat-bladed mixer may also be of benefit.

[0125] As noted, water may in some circumstances constitute the hardener for a hydraulic inorganic binder. Thus, in preparing some embodiments of the composition, water may be added gradually to a dry mixture of solid hydraulic inorganic binder and optionally further solid ingredients, while running the mixer. It is noted that the dry mixture to which water is initially added need not contain all solid ingredients of the composition: water may therefore be added to the mixer together with any remaining solids fraction.

[0126] In accordance with the broadest process aspects of the present disclosure, the compositions are applied to a substrate and then allowed to set in situ. Prior to applying the compositions, it is often advisable to pre-treat the relevant surfaces to remove foreign matter there from: this step can, if applicable, facilitate the subsequent adhesion of the compositions thereto. Such treatments are known in the art and can be performed in a single or multi-stage manner constituted by, for instance, the use of one or more of: an etching treatment with an acid suitable for the substrate and optionally an oxidizing agent; sonication; plasma treatment, including chemical plasma treatment, corona treatment, atmospheric plasma treatment and flame plasma treatment; immersion in a waterborne alkaline degreasing bath; treatment with a waterborne cleaning emulsion; treatment with a cleaning solvent, such as carbon tetrachloride or trichloroethylene; and, water rinsing, preferably with deionized or demineralized water. In those instances where a waterborne alkaline degreasing bath is used, any of the degreasing agent remaining on the surface should desirably be removed by rinsing the substrate surface with deionized or demineralized water. The compositions are then applied to the preferably pre-treated surfaces of the substrate by conventional application methods such as: brushing; roll coating; using a trowel; using a float; pumping; ramming; casting; gunning; and, spraying. The methods of gunning and spraying may be performed using conventional, commercially available equipment but selecting pressure conditions, nozzle type(s), conduit (hose) length and diameters such that clogging of the equipment is obviated and a controlled application pattern is achieved.

[0127] Whilst the application of the compositions by the aforementioned methods may be performed in a single or multiple step manner, it is recommended that the compositions be applied to a total wet fdm thickness of from 5 to 100 mm, for example from 5 to 75 mm or from 10 to 50 mm.

[0128] The setting of the compositions can occur at temperatures in the range of from 20 to 100°C, preferably from 20°C to 80°C, and in particular from 20°C to 60°C. The temperature that is suitable depends on the specific compounds present and the desired setting rate and can be determined in the individual case by the skilled artisan, using simple preliminary tests if necessary. Where applicable, the temperature of the mixture formed from the respective components of the composition may be raised above the mixing temperature and / or the application temperature using conventional means, including microwave induction. Alternatively or additionally, the compositions may be applied to a pre-heated substrate, this pre-heating facilitating the fast setting of the composition and an improved adhesion to the substrate. In an illustrative embodiment, the compositions are applied in a series of thin layers to attain a desired total thickness, wherein the substrate is maintained at a temperature of from 30 to 100°C throughout the application of each layer.

[0129] The composition of the present disclosure may be applied to existing structures fabricated from concrete, from refractory materials or from metallic materials. Further, the composition may be used in a restorative function, for instance to repair equipment wherein a coating or a refractory surface material has become displaced or abraded.

[0130] As noted above, the present disclosure provides of a method of monitoring an applied coating, said method comprising: providing a coated substrate of which the applied coating comprises a cured product obtained from the composition as defined hereinabove; and, measuring the resistivity of the coating over time.

[0131] The measurement of the resistivity of the coating may be conducted continuously, periodically or randomly. As used herein, the term “periodically” may be taken to mean periodic in time - that is after some predefined interval of time has elapsed - or may alternatively be taken to mean periodic in an event, that is after some event has occurred or has been detected. A predetermined interval may be a regular interval or an intermittent or irregular interval.

[0132] The resistivity measurements of the cementitious coating may be taken on the surface of material. A two-point probe method may be utilized for specimens having a resistivity of greater than 105Qcm. A four-point probe method may be utilized for specimens having a resistivity of 105Qcm or less. In the use of a four point probe, current flows through outer contacts near the sample edges and potential difference is gauged across inner contacts, this eliminating the effects of interfacial resistance between electrodes and the specimen. That aside, the surface on which the probes are placed should be flat without any surface leakage. Further, the diameter of contacts between the probes and the specimen should be smaller than the gap between probes. And as regards, a four point probe, the probes should touch the surface in a straight line or be disposed perimetrically where the Van der Pauw measurement method is employed.

[0133] The present disclosure further provides a system for monitoring a coated substrate, said system comprising: i) a coated substrate of which the coating comprises a cured product obtained from the composition as defined hereinabove, said coated substrate further comprising at least two spaced apart contact points; ii) at least two electrical contacts, each of the at least two electrical contacts being arranged at each of the at least two spaced apart contact points; and, Hi) a resistance measuring device configured to measure resistance across the at least two electrical contacts. Advantageously, the electrical contacts are arranged on the same substrate as the applied cementitious coating so that the electrically conductive cementitious coating partially extends above the electrical contacts.

[0134] In an embodiment, the system comprises at least three, for instance at least four electrical contacts arranged at a corresponding number of spaced apart contact points: the resistance measuring device is configured to measure the resistance across any combination of two different electrical contacts. By using more than two electrical contacts, it is possible to detect the localized deterioration of the coating more precisely. Having several electrical contacts allows a measurement of the change over time of the electrical resistance across different pairs of said contacts. These electrical contacts can be arranged in many different ways across the surface of the coating including perimetrically.

[0135] The system of the present disclosure relies on the special properties of the coating as described. By actively measuring the resistance across electrical contacts arranged at sides and / or the extremities of the coating or at other selected points withing the coating, it is possible to determine whether the coating has been subjected to erosion. The detection principle relies on the fact that the homogeneous medium of the coating makes the detection sensitive to a reduction in the cross-section of the coating, which reduction translates into an increase in the measured electrical resistance across electrical contacts arranged on either side of the reduced crosssection. Indeed, the higher the measured electrical resistance or the higher the increase in the measured resistance the more likely it is that the erosion has reached a significant depth inside the electrically conductive cementitious coating and that its extent is also large.

[0136] The present disclosure also envisages an asset - such as equipment, machinery or an installation - which has been provided with at least one system as described. In a particular embodiment, one or more systems may be disposed on the asset at different loci to enable the deterioration of the coatings at those loci to be monitored independently. The applied coating at each loci may be the same or different, wherein differences may be in the composition of the coating or the properties of the coating, such as coating thickness or basis weight.

[0137] The following examples are illustrative of the present invention and are not intended to limit the scope of the invention in any way.

[0138] EXAMPLES

[0139] The following commercial products are employed in the Examples:

[0140] IstraTM 40: Calcium aluminium cement, available from Calucem

[0141] Athlos SRI 200: Carbon Nanostructure Pellets (CNS) available from Cabot Corporation.

[0142] Peramin® CONPAC 500: Powdered superplasticizer available from Imerys.

[0143] ELKEM MICROSILICA® 940U: Undensified dry silica fume powder having a bulk density of 200 to 350 kg / m3, available from Elkem Materials.

[0144] Bindzil® 40 / 170: Deionized modified colloidal silica (silica sol: 40% by weight), available from Nouryon.

[0145] Duramet: Ferro silicon alloy powder containing Titanium and Aluminium, available from Washington Mills.

[0146] Borax lOFLO: Sodium tetraborate decahydrate (NfeEUOv.lOEEO) available from Ezretech.

[0147] All remaining ingredients mentioned herein below were obtained from Sigma Aldrich.

[0148] The compositions described were subjected to the following test:

[0149] Electrical Resistance Test: A composite test vehicle was provided which has 50 pm thick copper leads for wire connection. Cementitious materials according to Table 1 and Table 3 below but being devoid of carbon nanostructure (CNS) were prepared and applied to a wet film thickness of 5 mm over a mild steel panel (125 mm x 75 mm). The copper leads were placed on both ends of the coated panel. Compositions according to Table 1 and T able 3 below, which contain said CNS, were then cast over the obtained specimen at the stated wet thickness (5mm. 10mm) and subsequently the specimens were cured at room temperature for 7 days. The electrical resistance was measured according to ASTM D2739-97.

[0150] Examples 1 to 3

[0151] The coating compositions of Table 1 below were mixed in a high speed mixer disperser operated at 1000 rpm. The mixing procedure started with the addition to the mixer of the calcium alumina cement (CAC): the fumed silica, silicon carbide, carbon nanostructure (CNS) and super-plasticizer were then dry mixed therewith. The calcined bauxite and fused zirconia mullite were then added together with the remaining ingredients: water was gradually added to the obtained mixture over 30 minutes.

[0152] Table 1

[0153] The results of the electrical resistance test for these compositions are provided in Table 2.

[0154] Table 2

[0155] The loading of the carbon nanostructure (CNS) impacts electrical resistance: the most significant reduction of electrical resistance occurred when the loading of CNS was increased from 0.10 to 0.15 wt.%, based on the weight of the composition. Examples 4 to 6

[0156] The coating compositions of Table 3 below were mixed in a high speed mixer disperser operated at 1000 rpm. The mixing procedure commenced with the homogenization, over a duration of 30 minutes, of a dry filler mixture comprising the alumina powder, alumina ceramic pellets, Duramet, Borax powder, magnesium oxide and the carbon nanostructure (CNS). A premix of the colloidal silica dispersion and the potassium silicate solution was then added to the obtained mixture under further mixing.

[0157] Table 3

[0158] The results of the electrical resistance test for these compositions are provided in Table 4.

[0159] Table 4

[0160] As previously, the loading of the carbon nanostructure (CNS) impacts electrical resistance: the most significant reduction of electrical resistance occurred when the loading of CNS was increased from 0.10 to 0.15 wt.%, based on the total weight of all the non-volatile constituents in the composition. In view of the foregoing description and examples, it will be apparent to those skilled in the art that equivalent modifications thereof can be made without departing from the scope of the appended claims.

Claims

Claims1. A multicomponent composition comprising: a first component comprising an inorganic binder; and, a second component comprising a hardener for said inorganic binder, wherein said composition comprises water and further comprises: a) electrically conductive filler comprising or consisting of carbon nanostructures; and, b) at least one particulate refractory compound having a particle size in the range from 35 to 500 mesh as determined in accordance with ISO 3310-1:2016 Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth.

2. The composition according to claim 1, wherein: said first component comprises colloidal silica; and, said second component comprises at least one compound chosen from alkali metal silicates, alkaline earth metal silicates, magnesium oxide (MgO), sodium dihydrogen orthophosphate (NaHPO), sodium silica fluoride (NaSiF), sodium borate and mixtures thereof.

3. The composition according to claim 1, wherein: said first component comprises an inorganic hydraulic binder; and, said second component comprises water, wherein the composition is preferably characterized by a water factor of from 0.5 to 1.5, more preferably from 0.75 to 1.25.

4. The composition according to claim 3, wherein said first component comprises calcium aluminate cement.

5. The composition according to claim 3 comprising, based on the total weight of non-volatile constituents in the composition: from 20 to 60 wt.%, preferably from 35 to 60 wt.% of said calcium aluminate cement; from 0.05 to 7.5 wt.%, preferably from 0.05 to 5 wt.% of a) said electrically conductive filler comprising or consisting of carbon nanostructures; and, from 30 to 70 wt.%, desirably from 35 to 60 wt.% of b) said at least one particulate refractory compound.

6. The composition according to claim 4 or claim 5, wherein the calcium aluminate cement has a monocalcium aluminate (CA) content of least 50 wt.%, based on the total weight of the calcium aluminate cement.

7. The composition according to any one of claims 4 to 6, wherein the calcium aluminate cement has a refractoriness of at least 1000°C.

8. The composition according to any one of claims 1 to 7, wherein said electrically conductive fdler comprises, based on the total weight of all the non-volatile constituents in the composition: from 0.05 to 5 wt.%, preferably from 0.05 to 2 wt.% of carbon nanostructures; and, from 0 to 2.5 wt.%, preferably from 0 to 2 wt.% of electrically conductive fdler which is distinct from said carbon nanostructures (CNS).

9. The composition according to any one of claims 1 to 8, wherein the at least one refractory compound is chosen from: aluminum oxide (alumina, AI2O3); calcined bauxite; aluminium nitride; silicon oxide (SiCh); magnesium oxide (MgO); calcium oxide; zirconium oxide (zirconia, ZrCh); chromium oxide; silicon carbide (SiC); silicon nitride (SiN); tungsten carbide (WC); boron carbide (B4C); boron nitride (BN); alumina-zirconia; mullite (SABOs-SiCh); cordierite (2MgO-2A12O3-5SiC>2); fused zirconia mullite; and, mixtures thereof.

10. The composition according to any one of claims 1 to 8, wherein the at least one refractory compound is chosen from: alumina; silica; calcined bauxite; fused zirconia mullite; silicon carbide; and, mixtures thereof.

11. The composition according to any one of claims 1 to 10, wherein: the at least one refractory compound comprises calcined bauxite, wherein said calcined bauxite preferably has a particle size in the range of from 50 mesh to 500 mesh, as determined in accordance with ISO 3310-1:2016; and, said bauxite is present in the composition in an amount of from 15 to 35 wt.%, based on the total weight of non-volatile constituents in the composition.

12. The composition according to any one of claims 1 to 10, wherein: the at least one refractory compound comprises fused zirconia mullite, wherein said fused zirconia mullite preferably has a particle size smaller than 100 mesh, as determined in accordance with ISO 3310-1 :2016; and, said fused zirconia mullite is present in the composition an amount of from 15 to 35 wt.%, based on the total weight of non-volatile constituents in the composition.

13. The composition according to any one of claims 1 to 12 further comprising a superplasticizer, wherein said superplasticizer is preferably present in the composition in an amount of from 0.3 to 0.8 wt.%, based on the total weight of non-volatile constituents in the composition.

14. A cured product obtained from the composition as defined in any one of claims 1 to 13.

15. Use of the cured reaction product as defined in claim 14 as a coating on concrete, a refractory material or a metallic material.

16. A method of monitoring an applied coating comprising: providing a coated substrate of which the coating comprises a cured product obtained from the composition as defined any one of claims 1 to 13; and, measuring the resistivity of the coating over time.

17. A system for monitoring a coated substrate, said system comprising: i) a coated substrate of which the coating comprises a cured product obtained from the composition as defined any one of claims 1 to 13, said coated substrate further comprising at least two spaced apart contact points; ii) at least two electrical contacts, each of the at least two electrical contacts being arranged at each of the at least two spaced apart contact points; and,Hi) a resistance measuring device configured to measure resistance across the at least two electrical contacts.

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