A composite cement comprising calcined clay and carbonated olivine

Abstract

The present disclosure relates to a composite cement comprising calcined clay and carbonated olivine. The present disclosure also relates to methods of forming the composite cement comprising calcined clay and carbonated olivine.

Description

[0001] Title: A composite cement comprising calcined clay and carbonated olivine

[0002] FIELD OF THE INVENTION

[0003] The present disclosure relates to a composite cement comprising calcined clay and carbonated olivine. The present disclosure also relates to methods of forming the composite cement comprising calcined clay and carbonated olivine.

[0004] BACKGROUND OF THE INVENTION

[0005] Cement based materials make up more than half of all the materials used by humankind worldwide and account for approximately eight percent of global carbon dioxide emissions. There is a need to reduce global carbon dioxide emissions associated with cement based materials.

[0006] An example of a cement based material is concrete. Concrete traditionally comprises cement, aggregates and water. Concrete is a fundamental building material and is a widely used man-made material. The cement in the concrete is the mineral glue that binds the different components in the concrete together.

[0007] Some types of cement, such as Ordinary Portland cement (also known as CEM I), contain a material called “cement clinker”. Cement clinker is usually present at a high amount in the cement. For example, Ordinary Portland cement contains more than 90 percent by weight of cement clinker. Cement clinker is made from an abundant raw material, such as clay, that is cheaply available almost worldwide. The cement clinker production process requires grinding and calcining up to a temperature of 1450 °C a mixture of limestone, clays and other minor components. The mixture is then mixed with 3 to 5 percent by weight of gypsum to form Ordinary Portland cement. The predominant source of carbon dioxide emissions in the production of cement (and cement based materials generally) is the production of the cement clinker. For example, cement clinker production typically generates approximately 850 kg of carbon dioxide per ton of cement clinker produced. Typically, fossil fuel combustion and limestone decomposition in calcination during the production of thecement clinker are responsible for the majority, or all, of the carbon dioxide emissions.

[0008] Cement can be mixed with various supplements in different ratios and blends as established by the regulation UNI EN 197-1. In recent years, supplementary cementitious materials (SCMs) have been used in addition to or as a partial replacement of the cement clinker to reduce the carbon dioxide emissions associated with cement based materials. SCMs include materials such as ground granulated blast furnace slag (GGBFS), fly ash (FA), limestone filler, glass powder, natural pozzolana, calcined clays, silica fume, pumice, opaline rock, metakaolin and burnt shale. The use of SCMs is advantageous from an environmental and energy conservation viewpoint. By partly replacing cement clinker with SCMs, the environmental impact of cement based materials is improved. This is because the carbon dioxide emissions associated with cement clinker production, and thus cement based material production, is reduced. SCMs can also be formed as byproducts in industrial processes, and the reuse of SCMs further improves the energy efficiency of the cement based materials.

[0009] The use of SCMs in cement based materials is further advantageous because SCMs can improve the durability, reduce the permeability and enhance the strength of cement based materials. For example, SCMs contribute to the properties of cement based materials through hydraulic or pozzolanic activity. The pozzolanic reaction is a chemical reaction that can take place between calcium and a silicate, such as calcium hydroxide and silica oxide, in the presence of water to form calcium silicate hydrate. Calcium silicate hydrate has favourable cementitious properties and can be the main binding phase in cement based materials. As a further example, SCMs also affect the chemical and physical properties of cement based materials. SCMs improve the physical properties of cement based materials by reducing the water absorption and apparent porosity, thus increasing the durability of the cement based materials.

[0010] Unfortunately, the increasing demand for SCMs is misaligned with the availability of high quality SCMs (such as fly ash and ground granulated blast furnace slags). To address this issue, the use of calcined clay as a SCM has been increased. However,to be used as a SCM, the calcined clay needs to be in a form that has certain chemical characteristics. Firstly, the total amount of clay present in the calcined clay should not be below 30 weight percent of the total weight of the clay and is preferably 50 weight percent of the total weight of the clay or higher. This is because clay must be calcined at a certain temperature to be made amorphous and to be made useable as a pozzolanic material. The calcination temperature is related to the mineral content of the clay, and it is therefore important that the minerals present in the clay have a similar hydroxylation temperature to avoid incomplete metamorphization and / or sintering.

[0011] Furthermore, the kaolinite content of the calcined clay can alter the useability of the calcined clay. Whilst a high level of kaolinite is preferred in a calcined clay owing to kaolinite being a reactive clay type, the useability of a calcined clay having a high level of kaolinite is limited because of the high cost associated with such a calcined clay (there is a high level of competition for such a calcined clay with other applications). One drawback of a calcined clay with a high level of kaolinite is that the calcined clay has a high water demand when used as a SCM. On the other hand, a low level of kaolinite requires the addition of limestone for performance of the calcined clay to be maintained. However, limestone is a filler and not a SCM and therefore clay with a low level of kaolinite has limited potential in cement based products. An important note is that it is not always possible to extract preferential clays when quarrying because a quarry needs to be kept in balance.

[0012] Furthermore, when using clay, such as calcined clay, as a SCM in a high amount, the strength development of the cement based materials is compromised early and curing age and water demand are both increased.

[0013] There are therefore several considerations that need to be accounted for when using a SCM, such as calcined clay.

[0014] There is therefore a continued need for finding new types and sources of SCMs.SUMMARY OF THE INVENTION

[0015] The present disclosure relates to a composite cement comprising calcined clay and carbonated olivine. The present disclosure also relates to methods of forming the composite cement comprising calcined clay and carbonated olivine.

[0016] Representative features of the present invention are set out in the following clauses, which stand alone or may be combined, in any combination, with one or more features disclosed in the text and / or figures of the specification.

[0017] The present invention is as set out in the following clauses:

[0018] 1. A composite cement comprising:

[0019] cement clinker;

[0020] calcined clay; and,

[0021] carbonated olivine.

[0022] 2. The composite cement of clause 1 , wherein the composite cement consists of: cement clinker;

[0023] calcined clay; and,

[0024] carbonated olivine.

[0025] 3. The composite cement of clause 1 or clause 2, wherein the ratio of carbonated olivine to calcined clay (carbonated olivine: calcined clay) is: from 6:0.1 to 1:1 by weight; or, from 3:0.2 to 2:0.2 by weight.

[0026] 4. The composite cement of any one of clauses 1 to 3, wherein the calcined clay and carbonated olivine are present as a component of the composite cement at a combined weight of: from 15 to 99 weight percent; or, from 20 to 99 weight percent; or, from 25 to 97 weight percent; or, from 30 to 95 weight percent of the total weight of the composite cement.

[0027] 5. The composite cement of any one of clauses 1 to 4, wherein the calcined clay is present as a component of the composite cement at: from 5 weight percent orgreater; or, from 10 weight percent or greater; or, from 20 weight percent or greater; or, from 30 weight percent or greater; or, from 40 weight percent or greater; or, from 50 weight percent or greater of the total weight of the composite cement.

[0028] 6. The composite cement of any one of clauses 1 to 5, wherein the calcined clay is formed by the calcination of a clay wherein the clay comprises: kaolin clay; or, smectite clay; or, vermiculite clay; or, a combination thereof.

[0029] 7. The composite cement of any one of clauses 1 to 6, wherein the calcined clay comprises kaolinite at: from 15 to 95 weight percent; or, from 20 to 75 weight percent; or, from 25 to 55 weight percent; or, from 30 to 40 weight percent of the total weight of the calcined clay.

[0030] 8. The composite cement of any one of clauses 1 to 7, wherein the cement clinker is: Ordinary Portland cement clinker; and / or, sulfate resistant cement clinker; and / or, low heat cement clinker; and / or, white cement clinker; and / or, low-alkali cement clinker; and / or, belite calciumsulfoaluminate ternesite (BCT) cement clinker; and / or, a combination thereof.

[0031] 9. The composite cement of any one of clauses 1 to 8, wherein the composite cement comprises the cement clinker at: from 1 to 95 weight percent; or, from 3 to 75 weight percent; or, from 5 to 70 weight percent of the total weight of the composite cement.

[0032] 10. The composite cement of any one of clauses 1 to 9, wherein the composite cement comprises, or consists of:

[0033] cement clinker at from 5 to 70 weight percent of the total weight of the composite cement; and

[0034] a combination of calcined clay and carbonated olivine at from 30 to 95 weight percent of the total weight of the composite cement.

[0035] 11. The composite cement of any one of clauses 1 to 10, wherein the composite cement comprises a further supplementary cementitious material (SCM).12. The composite cement of clause 11 , wherein the further supplementary cementitious material (SCM) is: ground granulated blastfurnace slag (GGBFS); and / or, latent-hydraulic slag; and / or, pozzolanic slag; and / or, fly ash (FA); and / or, burnt shale; and / or, glass powder; and / or silica fume; and / or, natural pozzolana; and / or pumice; and / or, opaline rock; and / or, metakaolin; and / or, olivine; and / or, a combination thereof.

[0036] 13. The composite cement of clause 11 or clause 12, wherein the further supplementary cementitious material (SCM) is present at: from 1 to 30 weight percent; or, from 1.5 to 25 weight percent; or, from 2 to 20 weight percent of the total weight of the composite cement.

[0037] 14. The composite cement of any one of clauses 1 to 13, wherein the composite cement comprises a filler.

[0038] 15. The composite cement of clause 14, wherein the composite cement comprises the filler at: from less than 10 weight percent; or, from less than 5 weight percent; or, from less than 1 weight percent of the total weight of the composite cement.

[0039] 16. The composite cement of clause 14 or clause 15, wherein the filler is a mineralbased carbonate; optionally, wherein the mineral-based carbonate is: limestone; or, calcite; or, aragonite; or, vaterite; or, magnesium carbonate; or, dolomite; or, cement kiln dust; or, gypsum; or, a combination thereof.

[0040] 17. The composite cement of any one of clauses 1 to 13, wherein the composite cement does not comprise a filler.

[0041] 18. The composite cement of clause 17, wherein the filler is a mineral-based carbonate; optionally, wherein the mineral-based carbonate is: limestone; or, calcite; or, aragonite; or, vaterite; or, magnesium carbonate; or, dolomite; or, cement kiln dust; or, gypsum; or, a combination thereof.

[0042] 19. The composite cement of any one of clauses 1 to 13, wherein the composite cement does not comprise limestone.20. The composite cement of any one of clauses 1 to 19, wherein the composite cement comprises: admixtures; or, additives; or, a combination thereof.

[0043] 21. The composite cement of clause 20, wherein the admixtures are: water reducing agents; or, plasticizers; or, air entering agents; or, retarders; or, setting accelerators; or, rheology modifiers; or, a combination thereof.

[0044] 22. The composite cement of clause 20 or clause 21 , wherein the additives are: pigments; or, fibers; or, reinforcing elements; or, self-healing agents; or, a combination thereof.

[0045] 23. A method of preparing the composite cement of any one of clauses 1 to 22, the method comprising the steps of:

[0046] (a) providing cement clinker;

[0047] (b) providing calcined clay;

[0048] (c) providing carbonated olivine; and

[0049] (d) combining the cement clinker, calcined clay and carbonated olivine.

[0050] 24. The method of clause 23, wherein the carbonated olivine is prepared by reacting olivine with carbon dioxide in the presence of water; optionally,

[0051] (i) wherein the olivine is reacted with the carbon dioxide in the presence of water at a pressure of: from 10 to 300 bar; or, 25 to 250 bar; or, from 50 to 200 bar; and / or,

[0052] (ii) wherein the olivine is reacted with the carbon dioxide in the presence of water at a temperature of: from 50 to 350 °C; or, from 125 to 325 °C; or, from 150 to 300 °C; and / or,

[0053] (iii) wherein the olivine is reacted with the carbon dioxide in the presence of water at a pressure of from 50 to 200 bar and a temperature of 150 to 300 °C.

[0054] 25. The method of clause 23 or clause 24, wherein the method further comprises the steps of:

[0055] (e) providing admixtures and / or additives; and / or

[0056] (f) grinding the cement clinker, carbonated olivine and / or calcined clay.26. The method of clause 25, wherein the admixture and / or additives are:

[0057] (i) combined with the olivine during the preparation of carbonated olivine; (ii) combined with the cement clinker, calcined clay and carbonated olivine in step (d);

[0058] (iii) combined with the cement clinker, calcined clay and carbonated olivine in step (f); and / or

[0059] (iv) combined independently from each other.

[0060] 27. A cement based material comprising the composite cement of any one of clauses 1 to 22.

[0061] 28. Use of the composite cement of any one of clauses 1 to 22 for improving carbon dioxide performance of cement and / or cement based materials.

[0062] The present invention is also as set out in the following clauses:

[0063] 1A. A composite cement comprising:

[0064] cement clinker;

[0065] calcined clay; and,

[0066] carbonated olivine; or, a mixture of carbonated olivine and olivine.

[0067] 2A. The composite cement of clause 1 A, wherein the composite cement consists of:

[0068] cement clinker;

[0069] calcined clay; and,

[0070] carbonated olivine; or, a mixture of carbonated olivine and olivine.

[0071] 3A. The composite cement of clause 1 A or clause 2A, wherein the ratio of carbonated olivine to calcined clay (carbonated olivine: calcined clay); or, the ratio of the mixture of olivine and carbonated olivine to calcined clay (mixture of olivine and carbonated olivine: calcined clay), is: from 6:0.1 to 1:1 by weight; or, from 3:0.2 to 2:0.2 by weight; and / or,wherein the calcined clay and carbonated olivine; or, the calcined clay and the mixture of olivine and carbonated olivine, are present as a component of the composite cement at a combined weight of: from 15 to 99 weight percent; or, from 20 to 99 weight percent; or, from 25 to 97 weight percent; or, from 30 to 95 weight percent of the total weight of the composite cement; and / or,

[0072] wherein the calcined clay is present as a component of the composite cement at: from 5 weight percent or greater; or, from 10 weight percent or greater; or, from 20 weight percent or greater; or, from 30 weight percent or greater; or, from 40 weight percent or greater; or, from 50 weight percent or greater of the total weight of the composite cement; and / or,

[0073] wherein the calcined clay is formed by the calcination of a clay wherein the clay comprises: kaolin clay; or, smectite clay; or, vermiculite clay; or, a combination thereof; and / or,

[0074] wherein the calcined clay comprises kaolinite at: from 15 to 95 weight percent; or, from 20 to 75 weight percent; or, from 25 to 55 weight percent; or, from 30 to 40 weight percent of the total weight of the calcined clay; and / or,

[0075] wherein the cement clinker is: Ordinary Portland cement clinker; and / or, sulfate resistant cement clinker; and / or, low heat cement clinker; and / or, white cement clinker; and / or, low-alkali cement clinker; and / or, belite calciumsulfoaluminate ternesite (BCT) cement clinker; and / or, cement; and / or, a combination thereof; and / or,

[0076] wherein the composite cement comprises the cement clinker at: from 1 to 95 weight percent; or, from 3 to 75 weight percent; or, from 5 to 70 weight percent of the total weight of the composite cement

[0077] 4A. The composite cement of any one of clauses 1 A to 3A, wherein the composite cement comprises, or consists of:

[0078] cement clinker at from 5 to 70 weight percent of the total weight of the composite cement; anda combination of calcined clay and carbonated olivine at from 30 to 95 weight percent of the total weight of the composite cement; or, calcinated clay and the mixture of olivine and carbonated olivine at a combined weight of from 30 to 95 weight percent of the total weight of the composite cement.

[0079] 5A. The composite cement of any one of clauses 1 A to 4A, wherein the composite cement comprises a further supplementary cementitious material (SCM); optionally,

[0080] wherein the further supplementary cementitious material (SCM) is: ground granulated blastfurnace slag (GGBFS); and / or, latent-hydraulic slag; and / or, pozzolanic slag; and / or, fly ash (FA); and / or, burnt shale; and / or, glass powder; and / or silica fume; and / or, natural pozzolana; and / or pumice; and / or, opaline rock; and / or, metakaolin; and / or, olivine; and / or, a combination thereof; and / or,

[0081] wherein the further supplementary cementitious material (SCM) is present at: from 1 to 30 weight percent; or, from 1.5 to 25 weight percent; or, from 2 to 20 weight percent of the total weight of the composite cement.

[0082] 6A. The composite cement of any one of clauses 1 A to 5A, wherein the composite cement comprises a filler; optionally,

[0083] wherein the composite cement comprises the filler at: from less than 10 weight percent; or, from less than 5 weight percent; or, from less than 1 weight percent of the total weight of the composite cement; and / or,

[0084] wherein the filler is a mineral-based carbonate; optionally, wherein the mineral-based carbonate is: limestone; or, calcite; or, aragonite; or, vaterite; or, magnesium carbonate; or, dolomite; or, cement kiln dust; or, gypsum; or, a combination thereof.

[0085] 7A. The composite cement of any one of clauses 1 A to 5A, wherein the composite cement does not comprise a filler; optionally,wherein the filler is a mineral-based carbonate; optionally, wherein the mineral-based carbonate is: limestone; or, calcite; or, aragonite; or, vaterite; or, magnesium carbonate; or, dolomite; or, cement kiln dust; or, gypsum; or, a combination thereof

[0086] 8A. The composite cement of any one of clauses 1 A to 5A, wherein the composite cement does not comprise limestone.

[0087] 9A. The composite cement of any one of clauses 1 A to 8A, wherein the composite cement comprises: admixtures; or, additives; or, a combination thereof; optionally,

[0088] wherein the admixtures are: water reducing agents; or, plasticizers; or, air entering agents; or, retarders; or, setting accelerators; or, rheology modifiers; or, a combination thereof; and / or,

[0089] wherein the additives are: pigments; or, fibers; or, reinforcing elements; or, self-healing agents; or, a combination thereof.

[0090] 10A. A method of preparing the composite cement of any one of clauses 1A to 9A, the method comprising the steps of:

[0091] (a) providing cement clinker;

[0092] (b) providing calcined clay;

[0093] (c) providing carbonated olivine; or, providing a mixture of olivine and carbonated olivine; and

[0094] (d) combining the cement clinker, calcined clay and carbonated olivine; or, combining the cement clinker, calcined clay and the mixture of olivine and carbonated olivine.

[0095] 11A. The method of clause 10A, wherein the carbonated olivine is prepared by reacting olivine with carbon dioxide in the presence of water; optionally,

[0096] (i) wherein the olivine is reacted with the carbon dioxide in the presence of water at a pressure of: from 10 to 300 bar; or, 25 to 250 bar; or, from 50 to 200 bar; and / or,(ii) wherein the olivine is reacted with the carbon dioxide in the presence of water at a temperature of: from 50 to 350 °C; or, from 125 to 325 °C; or, from 150 to 300 °C; or, from 100 to 300 °C; or, from 100 to 250 °C; and / or,

[0097] (iii) wherein the olivine is reacted with the carbon dioxide in the presence of water at a pressure of from 50 to 200 bar and a temperature of 150 to 300 °C.

[0098] 12A. The method of clause 10A or clause 11A, wherein the carbonated olivine has a carbonation degree of: from 10 to 100 weight percent; or, from 40 to 99 weight percent; or, from 60 to 95 weight percent; or, from 75 to 90 weight percent of the total weight of the carbonated olivine based on the total amount of carbon dioxide released during thermal decomposition of the carbonated olivine as determined by thermogravimetric analysis (TGA).

[0099] 13A. The method of any one of clauses 10A to 12A, wherein the method further comprises the steps of:

[0100] (e) providing admixtures and / or additives; and / or

[0101] (f) grinding the cement clinker, carbonated olivine and / or calcined clay; or, grinding the cement clinker, the mixture of olivine and carbonated olivine, and / or calcinated clay.

[0102] 14A. The method of clause 13A, wherein the admixture and / or additives are:

[0103] (i) combined with the olivine during the preparation of carbonated olivine; (ii) combined with the cement clinker, calcined clay and carbonated olivine in step (d); or, combined with the cement clinker, calcinated clay and the mixture of olivine and carbonated olivine in step (d);

[0104] (iii) combined with the cement clinker, calcined clay and carbonated olivine in step (f); or, combined with the cement clinker, calcinated clay and the mixture of olivine and carbonated olivine in step (f); and / or

[0105] (iv) combined independently from each other.

[0106] 15A. A cement based material comprising the composite cement of any one of clauses 1A to 9A.16A. Use of the composite cement of any one of clauses 1A to 9A for improving carbon dioxide performance of cement and / or cement based materials, while maintaining the mechanical properties, as compressive strength.

[0107] 17A. The use of the composite cement of clause 16A, wherein the composite cement exhibits an eco-efficiency ratio greater than 1, indicating improved environmental performance relative to cement based materials based on only Portland cement (CEM I).

[0108] DETAILED DESCRIPTION

[0109] Embodiments of the invention are described below with reference to the accompanying drawings. The accompanying drawings illustrate various embodiments of systems, methods, and embodiments of various other aspects of the disclosure. Any person with ordinary skills in the art will appreciate that the illustrated element boundaries (e.g., boxes, groups of boxes, or other shapes) in the figures represent one example of the boundaries. It may be that in some examples one element may be designed as multiple elements or that multiple elements may be designed as one element. In some examples, an element shown as an internal component of one element may be implemented as an external component in another and vice versa. Furthermore, elements may not be drawn to scale. Nonlimiting and non-exhaustive descriptions are described with reference to the following drawings. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating principles.

[0110] Figure 1 shows the relationship between the ratio of carbonated olivine to calcined clay versus compressive strength at 28 days.

[0111] Embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings in which like numerals represent like elements throughout the several figures, and in which example embodiments are shown. Embodiments of the claims may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. It must also be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Although any systems and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the preferred systems and methods are now described.

[0112] Some of the terms used to describe the present invention are set out below:

[0113] “Carbonated olivine” refers to a mix of magnesium carbonate defined by the chemical formula MgCOsand amorphous silica defined by the chemical formula SiO2. For example, carbonated olivine is a material obtained from the carbonation of natural olivine, as defined in the following description. During the carbonation, part of the magnesium in the natural olivine reacts with carbon dioxide to form magnesium carbonate (MgCOs) and part of the silica from the crystal structure in the natural olivine is released to form amorphous silica (SiC ). Carbonated olivine may contain residual unreacted olivine.

[0114] “Carbonation” refers to a wet process of introducing carbon dioxide, within a high-pressure reactor, to transform magnesium and silica present in natural olivine into magnesium carbonate (MgCO3) and amorphous silica (SiO2), wherein the combination of the magnesium carbonate and amorphous silica is carbonated olivine. When the carbonation reaction does not reach full conversion, the resulting material contains unreacted olivine.

[0115] “Carbonation degree” refers to the proportion of a starting material (natural olivine) that is converted into carbonate-containing phases during reaction with carbon dioxide. The carbonation degree of olivine feedstock is determined by thermogravimetric analysis (TGA) based on the mass loss recorded between approximately 450 °C and 900 °C with release of carbon dioxide. Owing to the magnitude of the mass loss being directly proportional to the quantity of carbonateformed, the mass loss provides a quantitative measure of the extent of carbonation. For example, a carbonated olivine having a carbonation degree of 90 weight percent indicates that approximately 90 weight percent of the carbonated product is composed of magnesium carbonate (MgCO3) and amorphous silica (SiO2) and the remaining fraction consists of unreacted or partially reacted constituents such as magnesium orthosilicate (Mg2SiO4) and iron oxide (FeO or Fe2O3).

[0116] “Cement based materials” refers to a material that comprises cement and water. Cement based materials can further comprise aggregates (such as sand, gravel, crushed rocks, lightweight aggregates and / or a combination thereof), admixtures (such as water reducing agents, plasticizers, air entering agents, retarders, setting accelerators, rheology modifiers and / or a combination thereof), additives (such as pigments, fibers, fillers, reinforcing elements, self-healing agents and / or a combination thereof) and / or a combination thereof. Examples of cement based materials include, but are not limited to, concrete, mortars, plasters and known construction chemical products such as screed and / or tile adhesives.

[0117] “Cement clinker” refers to an intermediary product produced in the manufacture of cement. The cement clinker may be present in the form of “cement clinker” (i.e. , not grounded). Alternatively or additionally, the cement clinker may be present in the form of “cement” (i.e., grounded and optionally mixed with gypsum; or, additives; or, admixtures; or, a combination thereof).

[0118] “Composite cement” refers to a cement that comprises a supplementary cementitious material. The composite cement may be used in cement based materials such as, but not limited to, concrete, mortars and known construction chemical products such as screed and / or tile adhesives.

[0119] “Olivine” refers to a magnesium iron silicate and is defined by the chemical formula: (Mg,Fe)2SiO4. The ratio of magnesium to iron varies between the two endmembers of the solid solution states for olivine: forsterite (Mg endmember: Mg2SiO4) and fayalite (Fe endmember: Fe2SiO4). Other names for olivine include chrysolite, serpentine, dunite, forsterite, magnesium iron silicate, magnesium iron solid solutionsilicate, forsterite-fayalite solid solution, nesosilicate, orthosilicate, ultramafic, alkali earth silicate, and, magnesium silicate.

[0120] “Portland cement” refers to a finely ground hydraulic binder made exclusively from Portland cement clinker and a small, controlled amount of calcium sulfate (such as gypsum) added only to regulate the setting time. In its 100% pure form, it contains no fillers, supplementary cementitious materials, pigments, or chemical additives, consisting solely of the characteristic clinker minerals — tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A), and tetracalcium aluminoferrite (C4AF) — formed by heating a precise mixture of limestone and clay-derived materials to clinkering temperature.

[0121] “Pozzolanic activity” refers to how quicky a mineral, such as a silicate (such as silica and / or alumina), reacts with calcium (Ca2+) or calcium hydroxide (Ca(OH)2) in the presence of water to form compounds having cementitious properties. The compounds having cementitious properties include, but are not limited to, calcium silicate hydrates, calcium aluminate hydrates and calcium silicate aluminate hydrates. Pozzolanic activity can be measured by any method known in the art, such as the “activity index test” or the “Frattini test”.

[0122] “Supplementary cementitious materials” or “SCMs” refers to a material that partially replaces cement clinker in cement. SCMs can have pozzolanic properties. Materials with pozzolanic properties are characterised by a content of reactive silica and / or alumina which form strength providing calcium silicate hydrates, calcium hydrates and / or calcium silicate aluminate hydrates when water is added. SCMs includes both latent hydraulic and pozzolanic materials. However, unreactive or only slightly reactive materials, such as but not limited to limestone, are differentiated from SCMs. SCMs improve the durability and strength of the final product and reduce the permeability of the final product. Examples of SCMs include, but are not limited to, ground granulated blast furnace slag, fly ash, burnt shale, glass powder, silica fume, natural pozzolana, calcined clays, pumice, opaline rock, metakaolin, olivine and / or carbonated olivine.“Weight percent” refers to the percentage weight in grams of a component of a composition in every 100 grams of a composition. For example, if a composite cement contains carbonated olivine at 10 weight percent, then there is 10 g of carbonated olivine for every 100 g of the composite cement.

[0123] A composite cement

[0124] In one example of the present disclosure, the composite cement comprises cement clinker, calcined clay and carbonated olivine. Alternatively, the composite cement comprises cement clinker, calcined clay and a mixture of olivine and carbonated

[0125] Preferably, the composite cement consists of cement clinker, calcined clay and carbonated olivine. Alternatively, the composite cement consists of cement clinker, calcined clay and a mixture of olivine and carbonated olivine.

[0126] Preferably, the ratio of carbonated olivine to calcined clay (carbonated olivine: calcined clay) is: from 6:0.1 to 1:1 by weight; or, from 3:0.2 to 2:0.2 by weight. More preferably, the ratio of carbonated olivine to calcined clay (carbonated olivine: calcined clay) is 3:0.2 to 2:0.2 by weight.

[0127] Preferably, the ratio of the mixture of olivine and carbonated olivine to calcined clay (mixture of olivine and carbonated olivine: calcined clay) is: from 6:0.1 to 1:1 by weight; or, from 3:0.2 to 2:0.2 by weight. More preferably, the ratio of the mixture of olivine and carbonated olivine to calcined clay (mixture of olivine and carbonated olivine: calcined clay) is 3:0.2 to 2:0.2 by weight.

[0128] Preferably, the calcined clay and carbonated olivine are present as a component of the composite cement at a combined weight of: from 15 to 99 weight percent; or, from 20 to 99 weight percent; or, from 25 to 97 weight percent; or, from 30 to 95 weight percent of the total weight of the composite cement. More preferably, the calcined clay and carbonated olivine are present as a component of the composite cement at a combined weight of from 30 to 95 weight percent of the total weight of the composite cement.Preferably, the calcined clay and the mixture of olivine and carbonated olivine are present as a component of the composite cement at a combined weight of: from 15 to 99 weight percent; or, from 20 to 99 weight percent; or, from 25 to 97 weight percent; or, from 30 to 95 weight percent of the total weight of the composite cement. More preferably, the calcined clay and the mixture of olivine and carbonated olivine are present as a component of the composite cement at a combined weight of from 30 to 95 weight percent of the total weight of the composite cement.

[0129] Preferably, the calcined clay is present as a component of the composite cement at: from 5 weight percent or greater; or, from 10 weight percent or greater; or, from 20 weight percent or greater; or, from 30 weight percent or greater; or, from 40 weight percent or greater; or, from 50 weight percent or greater of the total weight of the composite cement.

[0130] Preferably, the calcined clay is formed by the calcination of a clay wherein the clay comprises: kaolin clay; or, smectite clay; or, vermiculite clay; or, a combination thereof.

[0131] Preferably, the calcined clay comprises kaolinite at: from 15 to 95 weight percent; or, from 20 to 75 weight percent; or, from 25 to 55 weight percent; or, from 30 to 40 weight percent of the total weight of the calcined clay. More preferably, the calcined clay comprises kaolinite at from 30 to 40 weight percent of the total weight of the calcined clay.

[0132] Preferably, the cement clinker is: Ordinary Portland cement clinker; and / or, sulfate resistant cement clinker; and / or, low heat cement clinker; and / or, white cement clinker; and / or, low-alkali cement clinker; and / or, belite calciumsulfoaluminate ternesite (BCT) cement clinker; and / or, a combination thereof. More preferably, the cement clinker is Ordinary Portland cement clinker.

[0133] Preferably, the composite cement comprises the cement clinker at: from 1 to 80 weight percent; or, from 3 to 75 weight percent; or, from 5 to 70 weight percent of the total weight of the composite cement. More preferably, the composite cementcomprises the cement clinker at 5 to 70 weight percent of the total weight of the composite cement.

[0134] Preferably, the composite cement comprises the Ordinary Portland cement clinker at 5 to 70 weight percent of the total weight of the composite cement.

[0135] Preferably, the composite cement comprises, or consists of, cement clinker at from 5 to 70 weight percent of the total weight of the composite cement and a combination of calcined clay and carbonated olivine at from 30 to 95 weight percent of the total weight of the composite cement.

[0136] Preferably, the composite cement comprises, or consists of, cement clinker at from 5 to 70 weight percent of the total weight of the composite cement and a combination of calcined clay and the mixture of olivine and carbonated olivine at from 30 to 95 weight percent of the total weight of the composite cement.

[0137] The composite cement may comprise a further supplementary cementitious material (SCM).

[0138] Preferably, the further supplementary cementitious material (SCM) is: ground granulated blastfurnace slag (GGBFS); and / or, latent-hydraulic slag; and / or, pozzolanic slag; and / or, fly ash (FA); and / or, burnt shale; and / or, glass powder; and / or silica fume; and / or, natural pozzolana; and / or pumice; and / or, opaline rock; and / or, metakaolin; and / or, olivine; and / or, a combination thereof.

[0139] The SCM may be a material with pozzolanic properties. The material with pozzolanic properties may be: ground granulated blast furnace slag; and / or, fly ash; and / or, burnt shale; and / or, glass powder; and / or, silica fume; and / or, natural pozzolana; and / or, pumice; and / or, opaline rock; and / or, metakaolin; and / or, carbonated olivine; and / or, a combination thereof.

[0140] Preferably, the further supplementary cementitious material (SCM) is present at: from 1 to 30 weight percent; or, from 1.5 to 25 weight percent; or, from 2 to 20 weight percent of the total weight of the composite cement. More preferably, the furthersupplementary cementitious material (SCM) is present at from 2 to 20 weight percent of the total weight of the composite cement.

[0141] The composite cement may comprise a filler. The composite cement may comprise the filler at: from less than 10 weight percent; or, from less than 5 weight percent; or, from less than 1 weight percent of the total weight of the composite cement. The filler may be a mineral-based carbonate, such as: limestone; or, calcite; or, aragonite; or, vaterite; or, magnesium carbonate; or, dolomite; or, cement kiln dust; or, gypsum; or, a combination thereof.

[0142] The composite cement may not comprise a filler. The composite cement may not comprise limestone.

[0143] The composite cement may comprise, and / or be mixed with: admixtures; or, additives; or, a combination thereof. The admixtures can be: water reducing agents; or, plasticizers; or, air entering agents; or, retarders; or, setting accelerators; or, rheology modifiers; or, a combination thereof. The additives can be: pigments; or, fibers; or, reinforcing elements; or, self-healing agents; or, a combination thereof.

[0144] Advantageously, by replacing cement clinker with calcined clay and carbonated olivine (or a mixture of olivine and carbonated olivine) in the production of cement based materials, a cement based material can be formed that has a reduced carbon dioxide footprint and also has comparable physical properties to a cement based material that does not comprise calcined clay and carbonated olivine (or a mixture of olivine and carbonated olivine).

[0145] Further advantageously, carbonated olivine is a mix of magnesium carbonate defined by the chemical formula MgCOsand amorphous silica defined by the chemical formula SiO2. The characteristic morphology of carbonated olivine has a positive impact on the rheology of cement allowing a reduction in calcined clay, plasticiser and filler demand (of the cement based material).

[0146] Further advantageously, the low water demand of carbonated olivine as a SCMs does not negatively impact the workability of the composite cement. Thisadvantageously reduces the water demand and thus improves the overall climate footprint of the resultant cement based material.

[0147] Further advantageously, the use of carbonated olivine (or a mixture of olivine and carbonated olivine) and calcined clays allows a high cement or cement clinker replacement of the cement based material, further reducing the carbon dioxide footprint of the resultant cement based material.

[0148] A method of making the composite cement

[0149] In one example of the present disclosure, the composite cement is made by a method that comprises the following steps:

[0150] (a) providing cement clinker;

[0151] (b) providing calcined clay;

[0152] (c) providing carbonated olivine; or, providing a mixture of olivine and carbonated olivine; and

[0153] (d) combining the cement clinker, calcined clay and carbonated olivine; or, combining the cement clinker, calcined clay and the mixture of olivine and carbonated olivine.

[0154] Preferably, the method includes the additional step of grinding the cement clinker in step (a). Alternatively or additionally, the method includes the additional step of grinding the cement clinker, calcined clay and carbonated olivine as step (f).

[0155] Alternatively or additionally, the method includes the additional step of grinding the cement clinker, calcined clay and the mixture of olivine and carbonated olivine as step (f).

[0156] Preferably, the method of making the composite cement further comprises the additional step of providing admixtures and / or additives as step (e).

[0157] Preferably, when the composite cement includes an admixture(s) and / or an additive(s), the admixture(s) and / or additive(s) are:

[0158] (i) combined with the olivine during the preparation of carbonated olivine;(ii) combined with the cement clinker, calcined clay and carbonated olivine in step (d); or, combined with the cement clinker, calcined clay and the mixture of olivine and carbonated olivine in step (d);

[0159] (iii) combined with the cement clinker, calcined clay and carbonated olivine in step (f); or, combined with the cement clinker, calcined clay and the mixture of olivine and carbonated olivine in step (f); and / or

[0160] (iii) combined independently from each other.

[0161] A method of making carbonated olivine

[0162] In one example of the present disclosure, the composite cement comprises carbonated olivine. The carbonated olivine is prepared by reacting olivine with carbon dioxide in the presence of water. The reaction can be represented with the following equation:

[0163] Mg2SiO4 + 2CO2 — 2MgCOs + SiO2

[0164] Preferably, the olivine is reacted with the carbon dioxide in the presence of water at a pressure of: from 10 to 300 bar; or, from 25 to 250 bar; or, from 50 to 200 bar.

[0165] Preferably, the olivine is reacted with the carbon dioxide in the presence of water at a temperature of: from 50 to 350 °C; or, from 125 to 325 °C; or, from 150 to 300 °C. Preferably, the olivine is reacted with the carbon dioxide in the presence of water at a temperature of: from 100 to 350 °C; or, from 100 to 300 °C; or, from 100 to 250 °C.

[0166] Preferably, the olivine is reacted with the carbon dioxide in the presence of water at a pressure of from 50 to 200 bar and a temperature of from 150 to 300 °C.

[0167] Preferably, the olivine is reacted with the carbon dioxide in the presence of water at a pressure of from 50 to 200 bar and a temperature of from 100 to 250 °C.

[0168] Preferably, the olivine carbonation has a carbonation degree of carbonated olivine of: from 10 to 100 weight percent; or, from 40 to 99 weight percent; or, from 60 to 95 weight percent; or from 75 to 90 weight percent of the total weight of the carbonatedolivine based on the total amount of carbon dioxide released during thermal decomposition of the carbonated product as determined by thermogravimetric analysis (TGA).

[0169] Preferably, the olivine is crushed and milled into fine particles prior to the reaction with the carbon dioxide in the presence of water. Preferably, the olivine is milled to a particle size of: from 700 mesh (20 pm) to 50 mesh (300 pm); or, from 600 mesh (23 pm) to 100 mesh (150 pm); or, from 500 mesh (25 pm) to 170 mesh (90 pm).

[0170] Preferably, the olivine is crushed to a particle size of from 500 mesh (25 pm) to 170 mesh (90 pm).

[0171] The olivine may be reacted with the carbon dioxide in the presence of water and a catalyst. The catalyst may be a chelating agent. The chelating agent may be: oxalic acid; and / or, citric acid; and / or, fulvic acid; and / or, ethylenediaminetetraacetic acid (EDTA); and / or, nitrilotriacetic acid (NTA); and / or, a combination thereof. Preferably, the chelating agent is oxalic acid.

[0172] The olivine may be reacted with the carbon dioxide in the presence of water and a salt. The salt may act as a catalyst. The salt may be: sodium bicarbonate; and / or, sodium carbonate; and / or, sodium chloride; and / or a combination thereof.

[0173] In one example of the present disclosure, the SCM carbonated olivine is prepared by a method set out in the paper titled “Kinetics and mechanism of mineral carbonation of olivine for CO2 sequestration” by F. Wang et al., Minerals Engineering 131 (2019), 185-197, which is hereby incorporated by reference in its entirety.

[0174] Cement based materials comprising the composite cement

[0175] In one example of the present disclosure, a cement based material comprises the composite cement.

[0176] Preferably, the cement based material is: concrete; or, mortar; or, plasters; or, screed; or, tile adhesives; or, a combination thereof.EXAMPLES

[0177] The following are non-limiting examples that discuss, with reference to tables and figures, the advantages of the present invention. The examples set forth herein are merely examples among other possible examples.

[0178] Example 1: Determining the compressive strength of cement based materials

[0179] In this non-limiting example, the compressive strength of a cement based material (mortar) comprising the composite cement as presently claimed was determined. As a comparison, the compressive strength of comparable cement based materials (mortar) was also determined.

[0180] Mortar was produced and tested following the EN 196-1:2016 standard. According to EN 196-1 :2016, mortar prisms for compressive strength testing were produced with a mixture of 450 (± 2) g cement or blended cement, 225 (± 1 ) g of water and one bag of 1 ,350 (± 5) g CEN Standard Sand. Mortar workability and consistency was evaluated with a mini slump test and the support of a manual flow table (EN 1015-18:2002 standard).

[0181] The cement used was Ordinary Portland Cement Cem I 52.5 R and met the requirements set by the European standard EN 197-1 :2011 on cements. The cement contained Ordinary Portland Cement clinker at from 95 to 100 weight percent by mass and minor additional constituents at from 0 to 5 weight % by mass of the total weight of the cement.

[0182] To keep the flow constant, a plasticiser (MasterSure HSE 1503 produced by Master Builders Solutions) was added.

[0183] The calcined clay was produced in a flash calciner at 850 °C. The calcined clay had a combined content of the silica and alumina of 86 weight percent of the total weight of the calcined clay, kaolinite content of 34 weight percent of the total weight of the calcined clay and a total clay content of 65 weight percent of the total weight of the calcined clay. After calcination, the calcined clay had an amorphous content of 35weight percent of the total weight of the calcined clay. The resultant calcined clay had a D50 of 23.3 pm measured by laser diffraction.

[0184] The carbonated olivine was produced via a wet process using a high pressure reactor. The process was performed using a carbon dioxide purity of 99.7 percent for four hours at 200 °C and 180 bar in the presence of sodium bicarbonate (NaHCOs). The starting material (olivine) had a magnesium oxide (MgO) content of 49.3 weight percent, a silica (SiC ) content of 41.6 weight percent and an iron oxide (FeO) content of 7.6 weight percent of the total weight of the starting material (olivine) measured by X-ray fluorescence (XRF) (Axios, Malvern Panalytical). The starting material had an olivine content of 89.4 weight percent of the total weight of the starting material measured by XRD (Bruker D2 Phaser instrument). The starting material (olivine) had a D50 of 7pm (measured by laser diffraction, Sympatec Helos). The starting material (olivine) was reacted with the carbon dioxide. The achieved product had a conversion rate (carbonation degree) of 90 weight percent of the total weight of the carbonated olivine. The carbonated olivine was a mix characterised by a magnesium carbonate (MgCO3) content of 60 weight percent and an amorphous silica (SiO2) content of 28.6 weight percent of the total weight of the carbonated olivine measured by XRD (Bruker D2 phaser instrument). The remaining part of the carbonated olivine included unreacted materials (such as olivine, and accessory minerals). The carbonated olivine had a D50 of 15.96 pm measured by laser diffraction.

[0185] The carbonation degree was calculated based on mass loss determined by Thermogravimetric analysis (TGA-Mettler Toledo TGA / DSC 3+) in the temperature range 450 °C to 900 °C. In this temperature range, magnesium carbonate in the solid carbonated product decomposes and carbon dioxide was released.

[0186] 2MgCOs + SiO2 -> 2MgO+ SiO2 + 2CO2

[0187] The release of carbon dioxide from the solid carbonated product resulted in a loss in mass of the solid material. The magnitude of the mass loss was directly proportional to the amount of carbonate formed, thereby providing a quantitative measure of the extent of carbonation.The cement, calcined clay and carbonated olivine were used as a dry powder, wherein the moisture content for the calcined clay and the carbonated olivine was below 0.2 by weight the total weight of the calcined clay and carbonated olivine (as measured with a thermogravimetric analysis performed up to 200 °C).

[0188] Mineralogical measurements were performed with XRD analysis with quantification of the Rietveld method.

[0189] The composition of five different cement based materials (mortar) and the measured compressive strength (CS) after two and twenty-eight days is shown in Table 1. The composition is shown relative to the amount of cement, calcined clay and carbonated olivine (without the standard sand). The plasticiser was added by need and is quantified in percentage by weight of cement (bwoc %).

[0190] Table 1: The composition of five different cement based materials (mortar) and the measured compressive strength (CS) after two and twenty-eight days. The amount of each component is as weight percentage of the total weight of the cement based material (mortar).

[0191] Component Fa Fb Fc Fd Fe

[0192] Cem 1 65 65 65 65 65 Calcined 35 NA 17.5 10 25

[0193] clay

[0194] Carbonated NA 35 17.5 25 10 olivine

[0195] Plasticiser 0.9 0 0.2 0.2 0.4 (bwoc %)

[0196] CS-2 days 24.1 25 23 23 23.2 (MPa)

[0197] CS-28 days 52.6 60.5 55 58 54

[0198] (MPa)

[0199]

[0200] As shown in Table 1, the carbonated olivine when used alone in substitution of CEMI is better performing than calcined clay when used alone in substitution of CEMI at 2 and 28 days. When the carbonated olivine is used together with calcined clays, for the same cement replacement level, the performances were enhanced in terms of mechanical development (in particular at 28 days) and rheology.

[0201] Figure 1 shows the relationship between the ratio of carbonated olivine to calcined clay versus compressive strength at 28 days. As shown in Figure 1 , when the carbonated olivine is used together with calcined clays, for the same cement replacement level (35 weight percent), the performance of the cement based material was enhanced in terms of mechanical development and rheology.

[0202] Overall, these results demonstrated that incorporating carbonated olivine, alone or in combination with calcined clay, at a cement substitution level of 35 weight percent yielded high-performance cement-based materials with fast strength gain, excellent 28-day compressive strength, and favourable fresh-state properties. The combined use of calcined clay and carbonated olivine provided a robust and efficient SCM solution suitable for high-performance, reduced-clinker cement formulations.

[0203] Example 2: Measurement of the global warming potential of the cement based materials of Example 1 and a cement based material made from cement (only)

[0204] In this non-limiting example, the global warming potential (GWP) of the cement based materials Fa to Fe of Example 1 was measured. In addition, the GWP of a cement based material made from cement (only) was analysed. The cement based material made from cement only is called Fref.

[0205] The carbonation process may have a global warming potential associated with energy and material inputs. The resulting carbonated olivine exhibits a GWP in the range of -0.15 to -0.40 KgCO2 / Kg. In a specific example, the carbonated olivine has a GWP of -0.30 KgCO2 / Kg.The value was calculated from considering the step of production (quarrying and crushing), shipping (from Norway to France), slurry preparation and handling (milling, mixing and preheating), reaction (heating), carbon dioxide preparation (carbon dioxide separation and compression) and post-processing (filtration and drying). A conversion rate of 90 percent from a starting olivine material that comprises 90 weight percent of the total weight of the starting olivine material is olivine (wherein 93 weight percent of the total weight of the starting olivine material is forsterite and 7 weight percent of the total weight of the starting olivine material is fayalite).

[0206] The GWP of Cem I and the plasticiser was determined from ICE Database V3.0 2019 and the GWP of calcined clay was determined from a scientific article from UN Environment et al., Eco-efficient cements: Potential economically viable solutions for a IOW-CO2 cement-based materials industry, Cement and Concrete Research 114 (2018) 2 -26.

[0207] The GWP of each material present in the cement based materials (mortar) is set out in Table 2.

[0208] Table 2: The GWP of each material present in the cement based materials (mortar).

[0209] Component GWP (kgCO2 / kg)

[0210] Cem 1 0.912

[0211] Calcined clay 0.275

[0212] Carbonated olivine -0.3

[0213] Plasticiser 1.88

[0214]

[0215] The GWP of each cement based material, Fa to Fe, from Example 1 is set out in Table 3. In addition, the GWP of a cement based material made from cement only (called Fref) is set out in Table 3.Table 3: The GWP of each cement based material, Fa to Fe, from Example 1 and a cement based material made from cement only (called Fref).

[0216] Component Fref Fa Fb Fc Fd Fe Cem 1 100 65 65 65 65 65 Calcined clay NA 35 NA 17.5 10 25 Carbonated NA NA 35 17.5 25 10 olivine

[0217] Plasticiser NA 0.9 0 0.2 0.2 0.4 GWP total

[0218] (kgCO2 / kg) 0.912 0.705 0.489 0.592 0.549 0.639

[0219]

[0220] Formulations incorporating both calcined clay and carbonated olivine (Fc, Fd, Fe) showed substantial environmental benefits. These blends delivered 35-40% GWP reduction relative to Fref while maintaining the high mechanical strength described in Example 1. The combined use of calcined clay and carbonated olivine therefore enabled a binder system that is both structurally efficient and significantly lower in embodied carbon dioxide than traditional cement.

[0221] Overall, the results demonstrated that substituting 35% of Portland cement with calcined clay, carbonated olivine, or mixtures thereof provided a marked reduction in environmental impact, with the lowest GWP values obtained when carbonated olivine is used either alone or at high ratios within the blend.

[0222] Example 3: High cement replacement with carbonated olivine and calcined clay: mechanical performances

[0223] In this non-limiting example, cement based material compositions comprising Portland cement, calcined clay, and carbonated olivine were prepared in order to assess their mechanical performance at high levels of clinker substitution. The cement based materials (in this example, mortar), identified as S1 to S4, contained 45 weight percent Portland cement and 55 weight percent of supplementary cementitious materials (SCMs) in varying proportions of calcined clay andcarbonated olivine of the total weight of the cement based materials, as shown in Table 4.

[0224] The cement based material, mortar, was produced and tested following the EN 196-1 :2016 standard. According to EN 196-1 :2016, mortar prisms for compressive strength testing were produced with a mixture of 450 (± 2) g cement or blended cement, 225 (± 1 ) g of water and one bag of 1 ,350 (± 5) g CEN Standard Sand.

[0225] Mortar workability and consistency was evaluated with a mini slump test and the support of a manual flow table (EN 1015-18:2002 standard). To keep the flow constant, a plasticiser (MasterSure HSE 1503 produced by Master Builders Solutions) was added.

[0226] The cement used was Ordinary Portland Cement Cem I 52.5 R and met the requirements set by the European standard EN 197-1 :2011 on cements. The cement contained Ordinary Portland Cement clinker at from 95 to 100 weight percent by mass and minor additional constituents at from 0 to 5 weight % by mass of the total weight of the cement.

[0227] The calcined clay was produced in a flash calciner at 850 °C. Mineralogical characterization was achieved before and after calcination using X-ray diffraction analysis with Brucker D2 Phases instrument with Rietveld method. Chemical analysis was performed by X-Ray Fluorescence (XRF) (Axios, Malvern Panalytical). The results are reported in Table 4:

[0228] Table 4. Chemical and mineralogical features of the two clays before and after calcination.

[0229] SiOz+AhOs AI2O3 / SiO2Kaolin Total clay Amorphous content content content (before (before (after calcination) calcination) calcination). (%) (%) (%) Calcined 93.7 0.41 56 73.5 56

[0230] clay 2

[0231]

[0232] The carbonated olivine was produced via a wet process using a high pressure reactor. The process was performed using a carbon dioxide purity of 99.7 percent for four hours at 200 °C and 180 bar in the presence of sodium bicarbonate (NaHCOs). The starting material (olivine) had a magnesium oxide (MgO) content of 49.3 weight percent, a silica (SiC ) content of 41.6 weight percent and an iron oxide (FeO) content of 7.6 weight percent of the total weight of the starting material (olivine) measured by X-ray fluorescence (XRF) (Axios, Malvern Panalytical). The starting material had an olivine content of 89.4 weight percent of the total weight of the starting material measured by XRD (Bruker D2 Phaser instrument). The starting material (olivine) had a D50 of 7pm (measured by laser diffraction, Sympatec Helos). The starting material (olivine) was reacted with the carbon dioxide. The achieved product had a conversion rate (carbonation degree) of 90 weight percent of the total weight of the carbonated olivine. The carbonated olivine was a mix characterised by a magnesium carbonate (MgCO3) content of 60 weight percent and an amorphous silica (SiO2) content of 28.6 weight percent of the total weight of the carbonated olivine measured by XRD (Bruker D2 phaser instrument). The remaining part of the carbonated olivine included unreacted materials (such as olivine and accessory minerals). The carbonated olivine had a D50 of 15.96 pm measured by laser diffraction.

[0233] The carbonation degree was calculated based on mass loss determined by Thermogravimetric analysis (TGA-Mettler Toledo TGA / DSC 3+) in the temperature range 450 °C to 900 °C. In this temperature range, magnesium carbonate in the solid carbonated product decomposes and carbon dioxide was released.

[0234] 2MgCOs + SiO2 -> 2MgO+ SiO2 + 2CO2

[0235] The release of carbon dioxide from the solid carbonated product resulted in a loss in mass of the solid material. The magnitude of the mass loss was directly proportional to the amount of carbonate formed, thereby providing a quantitative measure of the extent of carbonation.The cement, calcined clay and carbonated olivine were used as a dry powder, wherein the moisture content for the calcined clay and the carbonated olivine was below 0.2 by weight percent of the total weight of the calcined clay and carbonated olivine (as measured with a thermogravimetric analysis performed up to 200 °C).

[0236] The composition of four different cement based materials (mortar) with calcined clay 2 and carbonated olivine as an SCM and the measured compressive strength (CS) after two, seven and twenty-eight days is shown in Table 5. The composition of the four different cement based materials (mortar) is shown relative to the amount of cement, calcined clay and carbonated olivine (without the standard sand). The plasticiser was added by need and is quantified in percentage by weight of cement (bwoc %).

[0237] Table 5: Binder Mix design with carbonated olivine and calcined clay 2 and relative strength at 2, 7 and 28 days.

[0238] Component (%) S1 S2 S3 S4 Cem 1 45 45 45 45 Calcined clay 2 55 NA 20 45 Carbonated olivine NA 55 35 10

[0239] Plasticiser 1.26 0.13 0.35 0.91 (bwoc %)

[0240] CS-2 days 14.3 9.7 9.5 11.7 (MPa)

[0241] CS-7days 29.4 17.6 20.8 26.7 (MPa)

[0242] CS-28 days 43.1 39.0 44.0 43.9

[0243] (MPa)

[0244]

[0245] Despite the high replacement level, all cement based materials exhibited excellent compressive strength development. These values demonstrated that the combination of calcined clay and carbonated olivine enabled mechanical performance comparable to or exceeding traditional Portland-cement-based systems, even at clinker replacement levels of 55 weight percent. The S3 blend,containing 20% calcined clay and 35% carbonated olivine, achieved the highest strength (44.0 MPa), showing a positive interaction between the two SCMs.

[0246] A further advantage of the cement based materials lies in their reduced plasticiser demand, particularly in compositions containing higher proportions of carbonated olivine. S3 and S4 formulations required less plasticizer amount compared to S1 , demonstrating that carbonated olivine contributes to favourable fresh-state properties, improving workability without requiring high admixture dosages.

[0247] Taken together, these results show that blended binders comprising calcined clay and carbonated olivine provide a robust mechanical performance, improved rheological behaviour, and operational advantages in terms of reduced admixture consumption. These characteristics make the described binder system particularly suitable for low carbon cement applications requiring high structural performance.

[0248] A previously published study by M. Grigoletto (thesis abstract available publicly only) reports 28 day strengths of approximately 30 MPa for ternary binders containing carbonated olivine and calcined clays at 50% clinker replacement. In contrast, the present example demonstrates significantly higher mechanical strengths (39-44 MPa) at an even higher clinker replacement level (55%), thereby illustrating a clear performance improvement and an advancement over the referenced prior art.

[0249] Example 4: Measurement of the global warming potential and the environmental performance of the cement based materials of Example 3 and a cement based material made from cement (only)

[0250] In this non-limiting example, the global warming potential (GWP) of the cement based materials S1 to S4 of Example 3 was measured. In addition, the GWP of a cement based material made from cement (only) was analysed. The cement based material made from cement only is called Fref. having a compressive strength of 64.3 MPa at 28 days.

[0251] The carbonation process may have a global warming potential associated with energy and material inputs. The resulting carbonated olivine exhibits a GWP in therange of -0.15 to -0.40 KgCC / Kg. In a specific example, the carbonated olivine has a GWP of -0.30 KgCO2 / Kg.

[0252] The value was calculated from considering the step of production (quarrying and crushing), shipping (from Norway to France), slurry preparation and handling (milling, mixing and preheating), reaction (heating), carbon dioxide preparation (carbon dioxide separation and compression) and post-processing (filtration and drying). A conversion rate of 90 percent from a starting olivine material that comprises 90 weight percent of the total weight of the starting olivine material is olivine (wherein 93 weight percent of the total weight of the starting olivine material is forsterite and 7 weight percent of the total weight of the starting olivine material is fayalite).

[0253] The GWP of Cem I and the plasticiser was determined from ICE Database V3.0 2019 and the GWP of calcined clay was determined from a scientific article from UN Environment et al., Eco-efficient cements: Potential economically viable solutions for a IOW-CO2 cement-based materials industry, Cement and Concrete Research 114 (2018) 2 -26.

[0254] The GWP of each material present in the cement based materials (mortar) is set out in Table 2.

[0255] The GWP of each cement based material, S1 to S4, from Example 3 is set out in Table 6. In addition, the GWP of a cement based material made from cement only (called Fref) is set out in Table 6.

[0256] Table 6: The GWP of each cement based material, S1 to S4, from Example 3 and a cement based material made from cement only (called Fref).

[0257] Component Fref S1 S2 S3 S4

[0258] Cem 1 100 45 45 45 45

[0259] Calcined clay NA 55 NA 20 45

[0260] Carbonated NA NA 55 35 10

[0261] olivine

[0262] Plasticiser NA 1.26 0.13 0.35 0.91

[0263]

[0264] GWP total

[0265] (kgCO2 / kg) 0.912 0.584 0.247 0.367 0.520

[0266]

[0267] The GWP results demonstrated a substantial reduction in carbon dioxide emissions for all cement based material. While the reference Portland cement reference exhibited a GWP of 0.912 kg CO2 / kg, the cement based materials S1-S4 showed significantly reduced impacts, with values as low as 0.247 kg CO2 / kg for S2 (Table 6). This corresponds to a 73% reduction in embodied CO2relative to conventional cement.

[0268] To enable a performance-based comparison between the cement based materials, two environmental-mechanical indicators were calculated:

[0269] (1) Strength-Normalized GWP ( )

[0270] GWP (kg CO2e per kg cement based material)

[0271] =fc (MPa)

[0272] Wherein fcis the compressive strength of the material and a lower indicates a more eco-efficient cement based materials.

[0273] (2) Relative Eco-Efficiency vs Reference

[0274] r- „• • ( / c / / c,ref)

[0275] Eco-efficiency ratio =(Gwp / Gwp >()

[0276]

[0277] Wherein this ratio is dimensionless.

[0278] Values >1 indicate better performance per unit environmental burden compared to traditional CEM I.

[0279] The eco-efficiency index used herein is consistent with established performance-based indicators such as strength-normalized GWP commonly applied in cement based material efficiency analysis.The results are shown in Table 7. The environmental performances presented in Table 7 were calculated based on the mechanical results reported in Example 3, Table 5, and the GWP values reported in Example 4, Table 6.

[0280] Table 7: Environmental performance of the different cement based materials containing carbonated olivine and calcinated clay in different amounts.

[0281] <p = GWP / Strength Eco-Efficiency Ratio vs Cement based material

[0282] (kg CO2 / (kg-MPa)) Fref

[0283] Fref 0.01418 1.00

[0284] S1 0.01356 1.05

[0285] S2 0.00635 2.23

[0286] S3 0.00833 1.70

[0287] S4 0.01186 1.20

[0288]

[0289] Notably, binder S2 exhibited a <p value of 0.00635, corresponding to a reduction of more than a factor of two relative to the reference cement (<p = 0.01418), thereby indicating substantially enhanced environmental efficiency.

[0290] Eco efficiency values greater than 1 indicate superior environmental performance per unit of mechanical strength compared to the reference cement. The S2 and S3 compositions demonstrated especially strong performance, with S2 achieving an eco-efficiency ratio of 2.23, meaning that the binder delivers 123% more mechanical performance per unit of CO2emitted relative to reference Portland cement.

[0291] These results confirm that the sinergy of calcined clay and carbonated olivine, thus the combination not only maintains mechanical strength but also dramatically reduces environmental impact, offering a binder concept that is simultaneously high performance, low carbon, and resource efficient.

[0292] The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosedresult, as appropriate, may, separately, or in any combination of such features, be utilized for realizing the invention in diverse forms thereof.

[0293] Although certain example aspects of the invention have been described, the scope of the appended claims is not intended to be limited solely to these examples. The claims are to be construed literally, purposively, and / or to encompass equivalents.

Claims

CLAIMS1. A composite cement comprising:cement clinker;calcined clay; and,carbonated olivine; or, a mixture of carbonated olivine and olivine.

2. The composite cement of claim 1 , wherein the composite cement consists of: cement clinker;calcined clay; and,carbonated olivine; or, a mixture of carbonated olivine and olivine.

3. The composite cement of claim 1 or claim 2, wherein the ratio of carbonated olivine to calcined clay (carbonated olivine: calcined clay); or, the ratio of the mixture of olivine and carbonated olivine to calcined clay (mixture of olivine and carbonated olivine: calcined clay), is: from 6:0.1 to 1:1 by weight; or, from 3:0.2 to 2:0.2 by weight; and / or,wherein the calcined clay and carbonated olivine; or, the calcined clay and the mixture of olivine and carbonated olivine, are present as a component of the composite cement at a combined weight of: from 15 to 99 weight percent; or, from 20 to 99 weight percent; or, from 25 to 97 weight percent; or, from 30 to 95 weight percent of the total weight of the composite cement; and / or,wherein the calcined clay is present as a component of the composite cement at: from 5 weight percent or greater; or, from 10 weight percent or greater; or, from 20 weight percent or greater; or, from 30 weight percent or greater; or, from 40 weight percent or greater; or, from 50 weight percent or greater of the total weight of the composite cement; and / or,wherein the calcined clay is formed by the calcination of a clay wherein the clay comprises: kaolin clay; or, smectite clay; or, vermiculite clay; or, a combination thereof; and / or,wherein the calcined clay comprises kaolinite at: from 15 to 95 weight percent; or, from 20 to 75 weight percent; or, from 25 to 55 weight percent; or, from 30 to 40 weight percent of the total weight of the calcined clay; and / or,wherein the cement clinker is: Ordinary Portland cement clinker; and / or, sulfate resistant cement clinker; and / or, low heat cement clinker; and / or, white cement clinker; and / or, low-alkali cement clinker; and / or, belite calciumsulfoaluminate ternesite (BCT) cement clinker; and / or, cement; and / or, a combination thereof; and / or,wherein the composite cement comprises the cement clinker at: from 1 to 95 weight percent; or, from 3 to 75 weight percent; or, from 5 to 70 weight percent of the total weight of the composite cement4. The composite cement of any one of claims 1 to 3, wherein the composite cement comprises, or consists of:cement clinker at from 5 to 70 weight percent of the total weight of the composite cement; anda combination of calcined clay and carbonated olivine at from 30 to 95 weight percent of the total weight of the composite cement; or, calcinated clay and the mixture of olivine and carbonated olivine at a combined weight of from 30 to 95 weight percent of the total weight of the composite cement.

5. The composite cement of any one of claims 1 to 4, wherein the composite cement comprises a further supplementary cementitious material (SCM); optionally,wherein the further supplementary cementitious material (SCM) is: ground granulated blastfurnace slag (GGBFS); and / or, latent-hydraulic slag; and / or, pozzolanic slag; and / or, fly ash (FA); and / or, burnt shale; and / or, glass powder; and / or silica fume; and / or, natural pozzolana; and / or pumice; and / or, opaline rock; and / or, metakaolin; and / or, olivine; and / or, a combination thereof; and / or,wherein the further supplementary cementitious material (SCM) is present at: from 1 to 30 weight percent; or, from 1.5 to 25 weight percent; or, from 2 to 20 weight percent of the total weight of the composite cement.

6. The composite cement of any one of claims 1 to 5, wherein the composite cement comprises a filler; optionally,wherein the composite cement comprises the filler at: from less than 10 weight percent; or, from less than 5 weight percent; or, from less than 1 weight percent of the total weight of the composite cement; and / or,wherein the filler is a mineral-based carbonate; optionally, wherein the mineral-based carbonate is: limestone; or, calcite; or, aragonite; or, vaterite; or, magnesium carbonate; or, dolomite; or, cement kiln dust; or, gypsum; or, a combination thereof.

7. The composite cement of any one of claims 1 to 5, wherein the composite cement does not comprise a filler; optionally,wherein the filler is a mineral-based carbonate; optionally, wherein the mineral-based carbonate is: limestone; or, calcite; or, aragonite; or, vaterite; or, magnesium carbonate; or, dolomite; or, cement kiln dust; or, gypsum; or, a combination thereof8. The composite cement of any one of claims 1 to 5, wherein the composite cement does not comprise limestone.

9. The composite cement of any one of claims 1 to 8, wherein the composite cement comprises: admixtures; or, additives; or, a combination thereof; optionally,wherein the admixtures are: water reducing agents; or, plasticizers; or, air entering agents; or, retarders; or, setting accelerators; or, rheology modifiers; or, a combination thereof; and / or,wherein the additives are: pigments; or, fibers; or, reinforcing elements; or, self-healing agents; or, a combination thereof.

10. A method of preparing the composite cement of any one of claims 1 to 9, the method comprising the steps of:(a) providing cement clinker;(b) providing calcined clay;(c) providing carbonated olivine; or, providing a mixture of olivine and carbonated olivine; and(d) combining the cement clinker, calcined clay and carbonated olivine; or, combining the cement clinker, calcined clay and the mixture of olivine and carbonated olivine.

11. The method of claim 10, wherein the carbonated olivine is prepared by reacting olivine with carbon dioxide in the presence of water; optionally,(i) wherein the olivine is reacted with the carbon dioxide in the presence of water at a pressure of: from 10 to 300 bar; or, 25 to 250 bar; or, from 50 to 200 bar; and / or,(ii) wherein the olivine is reacted with the carbon dioxide in the presence of water at a temperature of: from 50 to 350 °C; or, from 125 to 325 °C; or, from 150 to 300 °C; or, from 100 to 300 °C; or, from 100 to 250 °C; and / or,(iii) wherein the olivine is reacted with the carbon dioxide in the presence of water at a pressure of from 50 to 200 bar and a temperature of 150 to 300 °C.

12. The method of claim 10 or claim 11 , wherein the carbonated olivine has a carbonation degree of: from 10 to 100 weight percent; or, from 40 to 99 weight percent; or, from 60 to 95 weight percent; or, from 75 to 90 weight percent of the total weight of the carbonated olivine based on the total amount of carbon dioxide released during thermal decomposition of the carbonated olivine as determined by thermogravimetric analysis (TGA).

13. The method of any one of claims 10 to 12, wherein the method further comprises the steps of:(e) providing admixtures and / or additives; and / or(f) grinding the cement clinker, carbonated olivine and / or calcined clay; or, grinding the cement clinker, the mixture of olivine and carbonated olivine, and / or calcinated clay.

14. The method of claim 13, wherein the admixture and / or additives are:(i) combined with the olivine during the preparation of carbonated olivine; (ii) combined with the cement clinker, calcined clay and carbonated olivine in step (d); or, combined with the cement clinker, calcinated clay and the mixture of olivine and carbonated olivine in step (d);(iii) combined with the cement clinker, calcined clay and carbonated olivine in step (f); or, combined with the cement clinker, calcinated clay and the mixture of olivine and carbonated olivine in step (f); and / or(iv) combined independently from each other.

15. A cement based material comprising the composite cement of any one of claims 1 to 9.

16. Use of the composite cement of any one of claims 1 to 9 for improving carbon dioxide performance of cement and / or cement based materials, while maintaining the mechanical properties, as compressive strength.

17. The use of the composite cement of claim 16, wherein the composite cement exhibits an eco-efficiency ratio greater than 1, indicating improved environmental performance relative to cement based materials based on only Portland cement (CEM I).

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