A composite cement comprising fly ash and carbonated olivine

Abstract

The present disclosure relates to a composite cement comprising carbonated olivine and ash, and in particular a composite cement comprising carbonated olivine and fly ash. The present disclosure also relates to methods of forming the composite cement comprising carbonated olivine and ash, and in particular a method of forming a composite cement comprising carbonated olivine and fly ash.

Description

[0001] Title: A composite cement comprising fly ash and carbonated olivine

[0002] FIELD OF THE INVENTION

[0003] The present disclosure relates to a composite cement comprising carbonated olivine and ash, and in particular a composite cement comprising carbonated olivine and fly ash. The present disclosure also relates to methods of forming a composite cement comprising carbonated olivine and ash, and in particular a method of forming a composite cement comprising carbonated olivine and fly ash.

[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 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 approximatelycombustion and limestone decomposition in calcination during the production of the cement 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), 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 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 ground granulated blast furnace slag). To address thisissue, fly ash has been used as a SCMs. However, the availability of fly ash is declining. This is because the primary source of fly ash is as a by-product from thermal power stations, such as coal-fired power stations, and such thermal power stations are being phased out globally in pursuit of net-zero emission targets.

[0011] In some cement based material formulations, cement clinker, fly ash and limestone are combined. Limestone can enhance the early mechanical strength of the cement based material produced, whilst the fly ash increased the strength of the cement based material at a later stage through pozzolanic reactions. In particular, limestone can optimise the porous structure of cement based materials, accelerate the precipitation of alite and stabilise ettringite. However, limestone does not exhibit pozzolanic behaviour and can be used only in a limited amount (for example, limestone can only replacement cement clinker by 20 weight percent or less of the total weight of the cement clinker prior to replacement). Furthermore, fly ash has reducing availability.

[0012] There is therefore a continued need for finding new types and sources of SCMs.

[0013] SUMMARY OF THE INVENTION

[0014] The present disclosure relates to a composite cement comprising carbonated olivine and ash, and in particular a composite cement comprising carbonated olivine and fly ash. The present disclosure also relates to methods of forming the composite cement comprising carbonated olivine and ash, and in particular a method of forming a composite cement comprising carbonated olivine and fly ash.

[0015] The development of low-carbon cement based materials requires a substantial reduction in cement clinker content while preserving mechanical performance and ensuring feasibility at industrial scale. Carbonated olivine represents a highly effective pathway to achieving deep carbon dioxide reductions. Beyond enabling significant clinker substitution, it contributes intrinsic carbon dioxide negativity through mineral carbonation, resulting in a markedly lower environmental footprint at the cement based material level. The strong pozzolanic reactivity of carbonated olivine supports both early and medium-age strength development of the cementbased material, allowing high levels of clinker replacement without compromising mechanical performance.

[0016] In parallel, the incorporation of additional supplementary cementitious materials (SCMs) such as fly ash can deliver further technical and economic advantages. Fly ash is a well-established pozzolanic material known to improve fresh workability, reduce heat of hydration, enhance long-term durability, and increase later-age strength, while typically lowering production costs. However, the long-term availability of fly ash is expected to decline as coal-based power generation continues to phase out, placing growing constraints on global SCM supply.

[0017] Against this backdrop, combining carbonated olivine with fly ash provides a flexible and resilient cement based material strategy. When available, fly ash can enhance performance and cost efficiency; meanwhile, carbonated olivine offers a stable, scalable, and deeply decarbonized substitution route that remains robust even as fly ash supplies diminish. Together, these materials form a synergistic system capable of delivering high eco-efficiency, reliable mechanical performance, and practical applicability in industrial cement and concrete production.

[0018] 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.

[0019] The present invention is as set out in the following clauses:

[0020] 1. A composite cement comprising:

[0021] cement clinker;

[0022] carbonated olivine; and

[0023] ash.

[0024] 2. The composite cement of clause 1 , wherein the composite cement consists of: cement clinker;

[0025] carbonated olivine; and

[0026] ash.3. The composite cement of clause 1 or clause 2, wherein the ash is fly ash.

[0027] 4. The composite cement of clause 3, wherein the fly ash is: siliceous fly ash; or, calcareous fly ash; or, class F fly ash; or, class C fly ash; or, a combination thereof.

[0028] 5. The composite cement of any one of clauses 1 to 4, wherein the ratio of carbonated olivine to ash (carbonated olivine: ash) is: from 6:0.1 to 1:1 by weight; or, from 3:0.2 to 2:0.2 by weight.

[0029] 6. The composite cement of any one of clauses 1 to 5, wherein the carbonated olivine and ash 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.

[0030] 7. The composite cement of any one of clauses 1 to 6, wherein the composite cement comprises ash at: from 5 to 45 weight percent; or, from 10 to 35 weight percent; or, from 15 to 25 weight percent of the total weight of the composite cement.

[0031] 8. The composite cement of any one of clauses 1 to 7, wherein the cement clinker is: Ordinary Portland cement clinker; or, sulfate resistant cement clinker; or, low heat cement clinker; or, white cement clinker; or, low-alkali cement clinker; or, belite calciumsulfoaluminate ternesite (BCT) cement clinker; or, a combination thereof.

[0032] 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.

[0033] 10. The composite cement of any one of clauses 1 to 9, wherein the composite cement comprises, or consists of:

[0034] cement clinker at from 5 to 70 weight percent of the total weight of the composite cement; andcarbonated olivine and ash at a combined weight of 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).

[0036] 12. The composite cement of clause 11, wherein the further supplementary cementitious material (SCM) is: ground granulated blast furnace slag (GGBFS); or, burnt shale; or, glass powder; or silica fume; or, natural pozzolana; or, pumice; or, opaline rock; or, metakaolin; or, olivine; or; calcined clay; or, a combination thereof.

[0037] 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.

[0038] 14. The composite cement of any one of clauses 1 to 13, wherein the composite cement comprises a filler.

[0039] 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.

[0040] 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, magnesium carbonate; or, dolomite; or, cement kiln dust, or, gypsum; or, a combination thereof.

[0041] 17. The composite cement of any one of clauses 1 to 13, wherein the composite cement does not comprise a filler.

[0042] 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, magnesium carbonate; or, dolomite; or, cement kiln dust; or, gypsum; or, a combination thereof.

[0043] 19. The composite cement of any one of clauses 1 to 13, wherein the composite cement does not comprise limestone.

[0044] 20. The composite cement of any one of clauses 1 to 19, wherein the composite cement comprises: admixtures; or, additives; or, a combination thereof.

[0045] 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.

[0046] 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.

[0047] 23. A method of preparing the composite cement of any one of clauses 1 to 22, the method comprising the steps of:

[0048] (a) providing cement clinker;

[0049] (b) providing ash;

[0050] (c) providing carbonated olivine; and

[0051] (d) combining the cement clinker, ash and carbonated olivine.

[0052] 24. The method of clause 23, wherein the ash is fly ash.

[0053] 25. The method of clause 23 or clause 24, 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,

[0054] (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,(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.

[0055] 26. The method of any one of clauses 23 to 25, wherein the method further comprises the steps of:

[0056] (e) providing admixtures and / or additives; and / or

[0057] (f) grinding the cement clinker, carbonated olivine and / or ash.

[0058] 27. The method of clause 26, wherein the admixture and / or additives are:

[0059] (i) combined with the olivine during the preparation of carbonated olivine; (ii) combined with the cement clinker, ash and carbonated olivine in step (d); (iii) combined with the cement clinker, ash and carbonated olivine in step (f); and / or

[0060] (iv) combined independently from each other.

[0061] 28. A cement based material comprising the composite cement of any one of clauses 1 to 22.

[0062] 29. 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.

[0063] The present invention is also as set out in the following clauses:

[0064] 1A. A composite cement comprising:

[0065] cement clinker;

[0066] carbonated olivine; and

[0067] ash.

[0068] 2A. The composite cement of clause 1 A, wherein the composite cement consists of:

[0069] cement clinker;

[0070] carbonated olivine; and

[0071] ash.3A. The composite cement of clause 1 A or clause 2A, wherein the ash is fly ash; optionally,

[0072] wherein the fly ash is: siliceous fly ash; or, calcareous fly ash; or, class F fly ash; or, class C fly ash; or, a combination thereof.

[0073] 4A. The composite cement of any one of clauses 1 A to 3A, wherein the ratio of carbonated olivine to ash (carbonated olivine: ash) is: from 6:0.1 to 1:1 by weight; or, from 3:0.2 to 2:0.2 by weight; and / or,

[0074] wherein the carbonated olivine and ash 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,

[0075] wherein the composite cement comprises ash at: from 5 to 45 weight percent; or, from 10 to 35 weight percent; or, from 15 to 25 weight percent of the total weight of the composite cement; and / or,

[0076] wherein the cement clinker is: Ordinary Portland cement clinker; or, sulfate resistant cement clinker; or, low heat cement clinker; or, white cement clinker; or, low-alkali cement clinker; or, belite calciumsulfoaluminate ternesite (BCT) cement clinker; or, cement; or, a combination thereof; and / or,

[0077] 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; and / or,

[0078] wherein the composite cement comprises, or consists of:

[0079] cement clinker at from 5 to 70 weight percent of the total weight of the composite cement; and

[0080] carbonated olivine and ash at a combined weight of from 30 to 95 weight percent of the total weight of the composite cement.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,

[0081] wherein the further supplementary cementitious material (SCM) is: ground granulated blast furnace slag (GGBFS); or, burnt shale; or, glass powder; or silica fume; or, natural pozzolana; or, pumice; or, opaline rock; or, metakaolin; or, olivine; or; calcined clay; or, a combination thereof.

[0082] 6A. The composite cement of clause 5A, 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.

[0083] 7A. The composite cement of any one of clauses 1 A to 6A, wherein the composite cement comprises a filler; optionally,

[0084] 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,

[0085] wherein the filler is a mineral-based carbonate; optionally, wherein the mineral-based carbonate is: limestone; or, calcite; or, aragonite; or, vaterite, 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 6A, wherein the composite cement does not comprise a filler; optionally,

[0087] wherein the filler is a mineral-based carbonate; optionally, wherein the mineral-based carbonate is: limestone; calcite; or, aragonite; or, vaterite, magnesium carbonate; or, dolomite; or, cement kiln dust; or, gypsum; or, a combination thereof.

[0088] 9A. The composite cement of any one of clauses 1 A to 6A, wherein the composite cement does not comprise limestone.10A. The composite cement of any one of clauses 1A to 9A, wherein the composite cement comprises: admixtures; or, additives; or, a combination thereof; optionally,

[0089] 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,

[0090] wherein the additives are: pigments; or, fibers; or, reinforcing elements; or, self-healing agents; or, a combination thereof.

[0091] 11A. A method of preparing the composite cement of any one of clauses 1A to 10A, the method comprising the steps of:

[0092] (a) providing cement clinker;

[0093] (b) providing ash;

[0094] (c) providing carbonated olivine; and

[0095] (d) combining the cement clinker, ash and carbonated olivine.

[0096] 12A. The method of clause 11A, wherein the ash is fly ash; and / or,

[0097] wherein the carbonated olivine is prepared by reacting olivine with carbon dioxide in the presence of water; optionally,

[0098] (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,

[0099] (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,

[0100] (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.

[0101] 13A. The method of clause 11A or clause 12A, 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 dioxidereleased during thermal decomposition of the carbonated olivine as determined by thermogravimetric analysis (TGA).

[0102] 14A. The method of any one of clauses 11A to 13A, wherein the method further comprises the steps of:

[0103] (e) providing admixtures and / or additives; and / or

[0104] (f) grinding the cement clinker, carbonated olivine and / or ash; optionally,

[0105] wherein the admixture and / or additives are:

[0106] (i) combined with the olivine during the preparation of carbonated olivine; (ii) combined with the cement clinker, ash and carbonated olivine in step (d); (iii) combined with the cement clinker, ash and carbonated olivine in step (f); and / or

[0107] (iv) combined independently from each other.

[0108] 15A. A cement based material comprising the composite cement of any one of clauses 1A to 10A.

[0109] 16A. Use of the composite cement of any one of clauses 1A to 10A for improving carbon dioxide performance of cement and / or cement based materials, while maintaining the mechanical properties, as compressive strength.

[0110] 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).

[0111] DETAILED DESCRIPTION

[0112] 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 thefigures 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.

[0113] Figure 1 presents the cumulative heat release normalised by weight of cement for cement based materials comprising carbonated olivine and / or fly ash.

[0114] 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.

[0115] 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.

[0116] Some of the terms used to describe the present invention are set out below:

[0117] “Biomass ash” refers to a by-product produced from the combustion of biomass materials, such as but not limited to, wood, crops and other organic matter.“Calcareous fly ash” refers to a by-product produced from exhaust gases that are produced during the combustion of pulverised coal at thermal power plants.

[0118] Calcareous fly ash contains a high amount of calcium oxide compared to other fly ashes. For example, calcareous fly ash contains from 10 weight percent or greater of calcium oxide.

[0119] “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 (SiCh). Carbonated olivine may contain residual unreacted olivine.

[0120] “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.

[0121] “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 carbonate formed, 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 theremaining fraction consists of unreacted or partially reacted constituents such as magnesium orthosilicate (Mg2SiO4) and iron oxide (FeO and / or Fe2O3).

[0122] “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.

[0123] “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).

[0124] “Class C fly ash” refers to a fly ash that has a high calcium oxide content compared to other fly ashes. For example, Class C fly ash contains from 20 weight percent or greater of calcium oxide. Class C fly ash is sourced from, but not limited to the following sources, subbituminous and lignite coals.

[0125] Class F fly ash” refers to a fly ash that has a low calcium oxide content compared to other fly ashes. For example, Class F fly ash contains from 7 or below of calcium oxide. Class F fly ash is sourced from, but not limited to the following sources, bituminous coal and anthracite coal.

[0126] “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.“Fly ash” refers to a by-product produced from exhaust gases that are produced during the combustion of pulverised coal in thermal power plants. At high temperatures in the thermal power plants, mineral components in the coal melt and form fused droplets. The fused droplets are fly ash.

[0127] “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 solution silicate, forsterite-fayalite solid solution, nesosilicate, orthosilicate, ultramafic, alkali earth silicate, and, magnesium silicate.

[0128] “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.

[0129] “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”.

[0130] “Siliceous fly ash” refers to a by-product produced from exhaust gases that are produced during the combustion of pulverised coal and thermal power plants.Siliceous fly ash is primarily composed of SiC>2, along with AI2O3 and Fe2Os.

[0131] Siliceous fly ash is a pozzolanic material.

[0132] “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.

[0133] “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.

[0134] A composite cement

[0135] In one example of the present disclosure, the composite cement comprises cement clinker, ash and carbonated olivine. Alternatively, the composite cement comprises cement clinker, ash and a mixture of olivine and carbonated olivine.

[0136] Preferably, the composite cement consists of cement clinker, ash and carbonated olivine. Alternatively, the composite cement consists of cement clinker, ash and a mixture of olivine and carbonated olivine.

[0137] Preferably, the ash is; fly ash; or, biomass ash; or, a combination thereof.

[0138] More preferably, the ash is fly ash.Preferably, the fly ash is: siliceous fly ash; or, calcareous fly ash; or, class F fly ash; or, class C fly ash; or, a combination thereof. Preferably, the fly ash has a sulfur trioxide (SO3) content of less than 3 weight percent by mass and a LOI of 7 percent or lower.

[0139] Preferably, the fly ash comprises SiC>2, AI2O3 and Fe2Os at a combined weight percentage of: from 70 weight percent or greater; or, from 75 weight percent or greater; or, from 80 weight percent or greater of the total weight of the fly ash.

[0140] Preferably, the ratio of carbonated olivine to ash (carbonated olivine: ash) 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 ash (carbonated olivine: ash) is from 3:0.2 to 2:0.2 by weight.

[0141] Preferably, the ratio of the mixture of olivine and carbonated olivine to ash (mixture of olivine and carbonated olivine: ash) 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 ash (mixture of olivine and carbonated olivine: ash) is from 3:0.2 to 2:0.2 by weight.

[0142] Preferably, the carbonated olivine and ash 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 carbonated olivine and ash 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.

[0143] Preferably, ash 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, ash 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.Preferably, the composite cement comprises ash at: from 5 to 45 weight percent; or, from 10 to 35 weight percent; or, from 15 to 25 weight percent of the total weight of the composite cement. More preferably, the composite cement comprises ash at from 15 to 25 weight percent of the total weight of the composite cement.

[0144] Preferably, the cement clinker is: Ordinary Portland cement clinker; or, sulfate resistant cement clinker; or, low heat cement clinker; or, white cement clinker; or, low-alkali cement clinker; or, belite calciumsulfoaluminate ternesite (BCT) cement clinker; or, a combination thereof. More preferably, the cement clinker is Ordinary Portland cement clinker.

[0145] Preferably, 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. More preferably, the composite cement comprises the cement clinker at 5 to 70 weight percent of the total weight of the composite cement.

[0146] Preferably, the composite cement comprises the Ordinary Portland cement clinker at 5 to 70 weight percent of the total weight of the composite cement.

[0147] 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 ash and carbonated olivine at from 30 to 95 weight percent of the total weight of the composite cement. More 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 fly ash and carbonated olivine at from 30 to 95 weight percent of the total weight of the composite cement.

[0148] 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 ash and the mixture of olivine and carbonated olivine at from 30 to 95 weight percent of the total weight of the composite cement. More preferably, the composite cement comprises, or consists of, cement clinker at from 5 to 70 weight percent ofthe total weight of the composite cement and a combination of fly ash and the mixture of olivine and carbonated olivine at from 30 to 95 weight percent of the total weight of the composite cement.

[0149] The composite cement may comprise a further supplementary cementitious material (SCM).

[0150] Preferably, the further supplementary cementitious material (SCM) is: ground granulated blast furnace slag (GGBFS); or, burnt shale; or, glass powder; or silica fume; or, natural pozzolana; or, pumice; or, opaline rock; or, metakaolin; or, olivine; or; calcined clay; or, a combination thereof.

[0151] The SCM may be a material with pozzolanic properties. The material with pozzolanic properties may be: ground granulated blastfurnace slag (GGBFS); and / or, burnt shale; and / or, glass powder; and / or, silica fume; and / or, natural pozzolana; and / or, calcined clays; and / or, pumice; and / or, opaline rock; and / or, metakaolin; and / or,; and / or, carbonated olivine; and / or, a combination thereof.

[0152] 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 further supplementary cementitious material (SCM) is present at from 2 to 20 weight percent of the total weight of the composite cement.

[0153] 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.

[0154] The composite cement may not comprise a filler. The composite cement may not comprise limestone.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.

[0155] Advantageously, by replacing cement clinker with ash 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 that also has comparable physical properties to a cement based material that does not comprise ash and carbonated olivine (or a mixture of olivine and carbonated olivine).

[0156] Further advantageously, carbonated olivine is a mix of magnesium carbonate defined by the chemical formula MgCOsand amorphous silica defined by the chemical formula SiCh. The characteristic morphology of carbonated olivine has a positive impact on the rheology of cement allowing a reduction in ash, plasticiser and / or filler demand (of the cement based material).

[0157] Further advantageously, the low water demand of carbonated olivine as a SCM does not negatively impact the workability of the composite cement. This advantageously reduces the water demand and thus improves the overall climate footprint of the resultant cement based material.

[0158] Further advantageously, the use of carbonated olivine (or a mixture of olivine and carbonated olivine) and ash 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.

[0159] A method of making the composite cement

[0160] In one example of the present disclosure, the composite cement is made by a method that comprises the following steps:

[0161] (a) providing cement clinker;(b) providing ash;

[0162] (c) providing carbonated olivine; or, providing a mixture of olivine and carbonated olivine; and

[0163] (d) combining the cement clinker, ash and carbonated olivine; or, combining the cement clinker, ash and the mixture of olivine and carbonated olivine.

[0164] The ash can be fly ash; or, biomass ash; or, a combination thereof. Preferably, the ash is fly ash.

[0165] 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, ash and carbonated olivine as step (f). Alternatively or additionally, the method includes the additional step of grinding the cement clinker, ash and the mixture of olivine and carbonated olivine as step (f).

[0166] Preferably, the method of making the composite cement further comprises the additional step of providing admixtures and / or additives as step (e).

[0167] Preferably, when the composite cement includes an admixture(s) and / or an additive(s), the admixture(s) and / or additive(s) are:

[0168] (i) combined with the olivine during the preparation of carbonated olivine; (ii) combined with the cement clinker, ash and carbonated olivine in step (d); or, combined with the cement clinker, ash and the mixture of olivine and carbonated olivine in step (d);

[0169] (iii) combined with the cement clinker, ash and carbonated olivine in step (f); or, combined with the cement clinker, ash and the mixture of olivine and carbonated olivine in step (f); and / or

[0170] (iii) combined independently from each other.

[0171] A method of making carbonated olivine

[0172] In one example of the present disclosure, the composite cement comprises carbonated olivine. The carbonated olivine is prepared by reacting olivine withcarbon dioxide in the presence of water. The reaction can be represented with the following equation:

[0173] Mg2SiO4 + 2CO2 — 2MgCOs + SiO2

[0174] 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.

[0175] 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.

[0176] 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.

[0177] 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 carbonated olivine based on the total amount of carbon dioxide released during thermal decomposition of the carbonated product as determined by thermogravimetric analysis (TGA).

[0178] 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.

[0179] 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).

[0180] Preferably, the olivine is crushed to a particle size of from 500 mesh (25 pm) to 170 mesh (90 pm).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.

[0181] 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.

[0182] 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 etal., Minerals Engineering 131 (2019), 185-197, which is hereby incorporated by reference in its entirety.

[0183] Cement based materials comprising the composite cement

[0184] In one example of the present disclosure, a cement based material comprises the composite cement.

[0185] Preferably, the cement based material is: concrete; or, mortar; or, plasters; or, screed; or, tile adhesives; or, a combination thereof.

[0186] EXAMPLES

[0187] 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.

[0188] Example 1: Determining the compressive strength of cement based materials

[0189] In this non-limiting example, the compressive strength of a cement based material (mortar) comprising the composite cement as presently claimed was determined. Asa comparison, the compressive strength of comparable cement based materials (mortar) was also determined.

[0190] 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).

[0191] The cement was partly replaced with siliceous fly ash and carbonated olivine. The cement, siliceous fly ash and carbonated olivine were combined and then water added to the combined materials to form the mortar.

[0192] 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.

[0193] The fly ash used was a commercially available siliceous fly ash. The siliceous fly ash met the requirements for application in cement. The siliceous fly ash had a calcium oxide (CaO) content of 6 weight percent, silicon dioxide (SiO2) content of 55 weight percent, alumina (AI2O3) content of 27 weight percent and an iron oxide (Fe2Os) content of 7 weight percent based on the total weight of the siliceous fly ash (measured by X-ray fluorescence (XRF), Axios, Malvern Panalytical). The siliceous fly ash had a D50 of 14.88 pm (measured by laser diffraction, Sympatec Helos).

[0194] 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 (SiCh) 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 (olivine) had an olivine content of 89.4 weight percent of the total weight of the starting material (olivine) 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.

[0195] 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.

[0196] 2MgCOs + SiO2->2MgO+ SiO2 + 2CO2

[0197] 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.

[0198] The cement, siliceous fly ash and carbonated olivine were used as a dry powder, wherein the moisture content for the siliceous fly ash and the carbonated olivine was below 0.2 by weight the total weight of the siliceous fly ash and carbonated olivine (as measured with a thermogravimetric analysis performed up to 200 °C).

[0199] The composition of six different cement based materials (mortar) and the measured compressive strength (CS) after seven and twenty-eight days is shown in Table 1.The composition is shown relative to the amount of cement, fly ash and carbonated olivine (without the standardised quartz sand).

[0200] Table 1 : The composition of six different cement based materials (mortar) and the measured compressive strength (CS) after seven and twenty-eight days. The amount of each component is as a weight percentage of the total weight of the cement based material (mortar).

[0201] Component Fref Fa Fb Fc Fd Fe Cem 1 100 70 70 70 64 64 Fly ash NA 30 NA 10 15 21 Carbonated NA NA 30 20 21 15 olivine

[0202] CS-7days 56.64 37.74 39.36 39.2 34.84 33.80 (MPa)

[0203] CS-28 days 64.34 43.96 57.69 57.68 50.46 51.00 (MPa)

[0204]

[0205] Advantageously, the partial substitution of cement with siliceous fly ash does not affect the workability of the cement based material (mortar) or the water demand of the cement based material (mortar).

[0206] Further advantageously, the use of carbonated olivine with fly ash allows partial substitution of the less available fly ash with carbonated olivine and improves the technical performance of the cement based material (mortar) contributing to an increase in strength development at seven and twenty-eight days. This is visible in Fc and Fd (as shown in Table 1), where good performances are maintained even for a high clinker replacement.

[0207] 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)

[0208] In this non-limiting example, the global warming potential (GWP) of the cement based materials Fref and Fe of Example 1 was measured.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 KgCCh / Kg. In a specific example, the carbonated olivine has a GWP of -0.30 KgCO2 / Kg.

[0209] 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).

[0210] The GWP of Cem I and fly ash was determined from ICE Database V3.02019.

[0211] The GWP of each material present in the cement based materials (mortar) is set out in Table 2.

[0212] Table 2: The GWP of each material present in the cement based materials (mortar).

[0213] Component GWP (kgCO2 / kg)

[0214] Cem I 0.912

[0215] Fly ash 0.00

[0216] Carbonated olivine -0.3

[0217]

[0218] The GWP of each cement based material, Fref to Fe, from Example 1 is set out in Table 3.Table 3: The GWP of each cement based material, Fref to Fe, from Example 1. Component Fref Fa Fb Fc Fd Fe Cem 1 100 70 70 70 64 64 Fly ash NA 30 NA 10 15 21 Carbonated NA NA 30 20 21 15 olivine

[0219] GWP total

[0220] (kgCO2 / kg) 0.912 0.638 0.548 0.578 0.520 0.538

[0221]

[0222] As shown in Table 3, owing to the low GWP contribution (zero) from the fly ash and the negative GWP contribution of the carbonated olivine, the cement based materials that comprise fly ash and carbonated olivine as a replacement to cement clinker have a low carbon footprint (up to 40 % lower than cement based materials that do not contain the replacement materials). At the same time, the mechanical strength of the cement based material is the same or improved.

[0223] To enable a performance-based comparison between the cement based materials set out in Tables 1 and 3, two environmental-mechanical indicators were calculated:

[0224] (1) Strength-Normalized GWP ( )

[0225] GWP (kg CO2e per kg cement based material)

[0226] =fc (MPa)

[0227] Wherein fcis the compressive strength of the material and a lower indicates a more eco-efficient cement based material.

[0228] (2) Relative Eco-Efficiency vs Reference

[0229] C / c / / c,ref)

[0230] Eco-efficiency ratio =

[0231]

[0232] (GWP / GWPref)

[0233] Wherein this ratio is dimensionless.Values >1 indicate better performance per unit environmental burden compared to traditional CEM I.

[0234] The eco-efficiency index used herein is consistent with established

[0235] performance-based indicators such as strength-normalized GWP commonly applied in cement based material efficiency analysis.

[0236] The results are shown in Table 4. The environmental performances presented in Table 4 were calculated based on the mechanical results reported in Example 1 and the GWP values reported in Example 2.

[0237] Table 4: Environmental performance of the different cement based materials containing carbonated olivine and fly ashes in different amounts.

[0238] <p = GWP / Strength Eco-Efficiency Ratio vs Cement based material

[0239] (kg CO2 / (kg MPa)) Fref

[0240] Fref 0.01418 1.00

[0241] Fa 0.01452 0.98

[0242] Fb 0.00950 1.49

[0243] Fc 0.01001 1.41

[0244] Fd 0.01030 1.37

[0245] Fe 0.01055 1.34

[0246]

[0247] As shown in Table 4, the cement based materials incorporating carbonated olivine (Fb, Fc, Fd, Fe) exhibited a markedly superior environmental-mechanical performance balance, delivering 34% to 49% higher strength per unit GWP relative to the reference cement based material (CEM I) (Fref). This demonstrated that the carbonated-olivine containing cement based materials not only reduced environmental impact but also yielded a higher mechanical return for each unit of embodied carbon. By contrast, although the cement based material containing 30% fly ash (Fa) achieves a reduction in GWP, the associated strength loss was sufficiently pronounced that its overall strength-normalised impact performance became slightly inferior to that of the reference cement based material (Fref), indicating no net gain in eco-efficiency.Accordingly, the results demonstrated that the incorporation of carbonated olivine into blended cements provided a dual and synergistic environmental and mechanical advantage, surpassing the benefits achievable through clinker reduction alone. Not only did the carbonated olivine contribute direct carbon dioxide negative effects and enhanced strength development, but the combined use of carbonated olivine with fly ash further amplified overall cement based material performance. This synergy between carbonated olivine and fly ash resulted in a composite cement based material that delivered markedly improved eco-efficiency relative to formulations relying solely on conventional SCMs, thereby confirming the advantageous interaction of these components within the blended cement based material matrix.

[0248] While any SCM decreases the clinker factor and thus lowers the GWP, the performance of carbonated olivine is particularly significant because it is inherently carbon dioxide negative. This means that its addition not only prevents additional emissions but also introduces embodied carbon sequestration, contributing to a substantial reduction in the overall cement based material level GWP even in the presence of other SCMs such as fly ash.

[0249] Example 3: Cumulative heat release of cement based materials having carbonated olivine and fly ash as SCMs

[0250] In this non-limiting example, the hydration behaviour and interactive effects of two supplementary cementitious materials (SCMs) relevant to the present application — carbonated olivine (OC) and fly ash (FA) — when jointly employed as binary replacements for ordinary Portland cement (OPC) was investigated. The objective was to quantify the synergistic hydration response arising from combined OC-FA incorporation, where “synergy” is defined as a cumulative heat release that exceeds the theoretical linear sum of the individual contributions expected from OC and FA when each acts independently.

[0251] Isothermal calorimetry provided a direct measurement of the heat released during cement hydration and supplementary cementitious material (SCM) reactions. When two SCMs were combined (e.g., carbonated olivine and fly ash), their interaction maylead to hydration behaviour that deviates from the simple linear superposition of the individual SCM responses. This deviation is commonly referred to as synergy. A positive synergic effect implies that the combined system exhibits a higher degree of reactivity than expected from the individual SCM components alone.

[0252] In this example, the hydration kinetic was assessed by isothermal calorimetry (8-channel TAM Air isothermal calorimeter) and expressed as normalized cumulative heat per gram of cement. The cement based materials (as pastes) were measured for 7 days at 20 °C.

[0253] The synergy was quantified by comparing the measured cumulative heat release of binary SCM blends (i.e. , cement based materials (as pastes) that comprise carbonated olivine and fly ash) to the ideal heat calculated via linear interpolation of the corresponding single-SCM system (i.e., cement based materials (as pastes) that comprise carbonated olivine or fly ash). The composition of such cement based materials (as pastes) is set out in Table 5.

[0254] To determine whether the cement based materials (as pastes) that comprise carbonated olivine and fly ash exhibit synergy owing to the presence of carbonated olivine and fly ash, an ideal (non-interactive) heat value Hidea| was calculated for each cement based material by linearly combining the heats of the single-SCM references (i.e., cement based materials (as pastes) that comprise carbonated olivine or fly ash) according to their internal fractions within the 40% replacement of cement:

[0255] ^ideal =x’ #OC40 + (1 “x) ’ ^FA40

[0256] wherein:

[0257] • HOC4O represents the cumulative heat release measured for a cement based material paste containing 40 weight percent carbonated olivine of the total weight of the cement based material (wherein the carbonated olivine is the sole SCM replacement);• #FA4O represents the cumulative heat release measured for a cement based material paste containing 40 weight percent fly ash of the total weight of the cement based material (wherein the fly ash is the sole SCM replacement); and

[0258] • x represents the fraction of OC within the 40 weight percent SCM portion of the binary cement based material paste (i.e. , a cement based material paste that comprises carbonated olivine and fly ash), calculated by the equation below:

[0259] _ OC replacement

[0260]

[0261]

[0262] The synergy is defined as:

[0263] Synergy — HbienC| — H^eai.

[0264] Cement based material pastes having the composition set out in Table 5 were prepared. The water / powder ratio (cement and SCM) was fixed at 0.5. All cement based material pastes had a total cement replacement of 40 weight percent of the total weight of the cement based material paste.

[0265] All the materials used are the same reported in Example 1.

[0266] Table 5. Composition of the cement based material pastes, wherein OPC is Ordinary Portland Cement, OC is carbonated olivine and FA is fly ash.

[0267] 30 OC- 10 oc- 20 OC- Component OPC 40 OC 40 FA

[0268] 10 FA 30 FA 20 FA CEM 152.5R

[0269] 100 60 60 60 60 60 (%)

[0270] Carbonated

[0271] olivine (OC) 0 40 0 30 10 20 (%)

[0272] Fly Ash (FA)

[0273] 0 0 40 10 30 20

[0274] (%)

[0275]

[0276] In Figure 1 , the cumulative heat release of all cement based material paste formulations is shown, normalised by the mass of cement present in each cement based material paste.

[0277] All cement based material pastes containing supplementary cementitious materials (SCMs) exhibited an apparently higher normalised cumulative heat release compared to the OPC control (the cement based material comprising 100% OPC). This outcome was consistent with the fact that: (i) the measured heat of hydration is expressed per unit of residual cement, while the total thermal output reflects contributions from both cement hydration and SCM-related reactions; and (ii) at a 40% replacement level, the reduced cement content decreases the normalisation denominator, thereby increasing the apparent heat per gram of cement. The observed trend confirms that the combined presence of OC and FA does not inhibit cement hydration and instead contributes to a slightly elevated cumulative heat release per unit cement, indicating active participation in hydration processes.

[0278] Notably, the cement based material paste comprising 20-20 OC-FA demonstrated the highest normalised intensity, suggesting a particularly favourable interactive effect between the two SCMs.

[0279] Table 6. The cumulative heat and calculated synergy for all the cement based material pastes set out in Table 5 at 72 and 168 hours (h).

[0280] Cement Normalized Normalized

[0281] Calculated Calculated based cumulative cumulative

[0282] synergy at 72 h synergy at 168 material heat ( J / g heat (J / g

[0283] (J / g cement) h (J / g cement) pastes cement) 72 h cement) 168 h

[0284] 40 OC 42.6425 50.5214 / /

[0285] 40 FA 43.9581 51.1765 / /

[0286] 30 OC-10 FA 43.5053 51.2649 +0.534 +0.580

[0287] 10 OC-30 FA 44.4552 51.9954 +0.826 +0.983

[0288] 20 OC-20 FA 44.2045 51.9544 +0.904 +1.105

[0289]

[0290] The data reported in Table 6 demonstrated a clear non-linear enhancement in hydration heat when carbonated olivine and fly ash are used jointly, compared to thebehaviour predicted by linear dilution of the individual SCM system. The excess heat released above the ideal baseline indicated that OC and FA mutually activate each other beyond their independent reactivity.

[0291] All binary blends outperformed their ideal linear benchmarks, proving that OC and FA interacted cooperatively. The synergic enhancement increased between 72 h and 168 h, indicating that later-age hydration processed most from the interaction. In particular the cement based material paste comprising 20 OC-20 FA provided the strongest synergy at both ages, with a synergy magnitude at 168 h exceeding +1.1 J / g cement, confirming a sustained and significant departure from ideal

[0292] non-interactive behaviour.

[0293] 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 disclosed result, as appropriate, may, separately, or in any combination of such features, be utilized for realizing the invention in diverse forms thereof.

[0294] 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;carbonated olivine; andash.

2. The composite cement of claim 1, wherein the composite cement consists of: cement clinker;carbonated olivine; andash.

3. The composite cement of claim 1 or claim 2, wherein the ash is fly ash; optionally,wherein the fly ash is: siliceous fly ash; or, calcareous fly ash; or, class F fly ash; or, class C fly ash; or, a combination thereof.

4. The composite cement of any one of claims 1 to 3, wherein the ratio of carbonated olivine to ash (carbonated olivine: ash) 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 carbonated olivine and ash 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 composite cement comprises ash at: from 5 to 45 weight percent; or, from 10 to 35 weight percent; or, from 15 to 25 weight percent of the total weight of the composite cement; and / or,wherein the cement clinker is: Ordinary Portland cement clinker; or, sulfate resistant cement clinker; or, low heat cement clinker; or, white cement clinker; or, low-alkali cement clinker; or, belite calciumsulfoaluminate ternesite (BCT) cement clinker; or, cement; 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 cement; and / or,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; andcarbonated olivine and ash 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 blast furnace slag (GGBFS); or, burnt shale; or, glass powder; or silica fume; or, natural pozzolana; or, pumice; or, opaline rock; or, metakaolin; or, olivine; or; calcined clay; or, a combination thereof.

6. The composite cement of claim 5, 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.

7. The composite cement of any one of claims 1 to 6, 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, magnesium carbonate; or, dolomite; or, cement kiln dust, or, gypsum; or, a combination thereof.

8. The composite cement of any one of claims 1 to 6, 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; calcite; or, aragonite; or, vaterite, magnesium carbonate; or, dolomite; or, cement kiln dust; or, gypsum; or, a combination thereof.

9. The composite cement of any one of claims 1 to 6, wherein the composite cement does not comprise limestone.

10. The composite cement of any one of claims 1 to 9, 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.

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

12. The method of claim 11 , wherein the ash is fly ash; and / or,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.

13. The method of claim 11 or claim 12, 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).

14. The method of any one of claims 11 to 13, 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 ash; optionally,wherein the admixture and / or additives are:(i) combined with the olivine during the preparation of carbonated olivine; (ii) combined with the cement clinker, ash and carbonated olivine in step (d); (iii) combined with the cement clinker, ash 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 10.

16. Use of the composite cement of any one of claims 1 to 10 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 environmentalperformance relative to cement based materials based on only Portland cement (CEM I).

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