EP3830054A1

EP3830054A1 - Fe-rich binder

Info

Publication number: EP3830054A1
Application number: EP19749690.4A
Authority: EP
Inventors: Lukas ARNOUT; Yiannis PONTIKES
Original assignee: Katholieke Universiteit Leuven
Current assignee: Katholieke Universiteit Leuven
Priority date: 2018-07-31
Filing date: 2019-07-31
Publication date: 2021-06-09
Also published as: CA3108144C; CL2021000255A1; WO2020025691A1; AU2019314882B2; GB201812450D0; AU2019314882A1; CA3108144A1

Abstract

The invention relates to binders for mortar or concrete comprising a mixture consisting of: a) from 40 to 95 wt% of an Fe-comprising glass or Fe-comprising metallurgical slag, wherein the glass or slag comprises more than 30 wt% Fe, expressed as Fe203, b) from 1 to 40 wt% of a calcium comprising additive, wherein the additive comprises more than 30 wt% Ca, expressed as calcium oxide and c) from 0.5 to 20 wt% of an alkali, wherein the sum of the percentages of a) b) and c) in the mixture, calculated on a dry basis, is 100%.

Description

FE-RICH BINDER

Field of the Invention

The present invention concerns the synthesis of a durable, sustainable and safe- to-use binder that contains a high total content of Fe-rich phases.

Background of the invention

In 2016, the cement industry produced around 4.2 billion tons of binder, emitting nearly 1.5 Gt of C0₂, representing around 5-8 % of the total anthropogenic CO2 emissions [Andrew (2018) Earth Syst. Sci. Data 10, 195-217 (2018)]. From a different perspective, that means that on an annual basis the global cement industry is emitting what Europe as a whole emits in the same timeframe. In light of the foregoing fact, alternative binders less aggressive to the environment, partially replacing Ordinary Portland Cement (OPC) are clearly needed. An efficient way of decreasing the environmental footprint of cement/concrete would be to substitute the use of classic Ordinary Portland Cement by secondary resources, that are otherwise down-cycled or landfilled.

In today's concrete industry a lot of industrial by-products are already incorporated as reactive cement replacer, inert filler or aggregate. In addition to their beneficial impact on the environment, by-products improved the properties of the final products [Siddique & Khan (2011) in "Supplementary Cementing Materials Springer", ISBN: 978-3-642-17865-8] : silica fume addition increases the strength of the concrete, ground granulated blast furnace slag has a beneficial impact on durability and acid resistance, limestone reduces the chemical shrinkage, whereas fly ash from coal combustion increases the alkali and chloride resistances. Other alternative materials such as Fe-rich slags from the Pb, Zn, Cu, Ni,... industry are currently mostly used as aggregates for asphalt, next to sandblasting [Dhir et al. (2017). Elsevier, ISBN: 978-0-08-100986-8]. The potential as an aggregate for concrete or as a supplementary cementitious material (SCM) has been proven in many studies, but the latter is not materialized in real life applications at the moment [Dhir et al. (2017) cited above] due to technical and logistic issues that have not been resolved. Alkali-activation : a blend of solids mixed with an alkali-source: Various binders, alternatives to Ordinary Portland Cement (OPC) with metallurgical residues incorporated, have been explored lately. Most of these works have focused on the area of blended cements, where the residue is behaving as pozzolana or latent hydraulic, or on the area of alkali activation.

Regarding the durability aspects of the alkali-activated systems, Ismail et al. (2013) [Constr. Build. Mater. 48, 1187-1201] mentioned that a denser Al- substituted calcium silicate hydrate (C-A-S-H) gel in alkali activated systems (AAS) concrete contributed to a higher durability under chloride exposure, while the inclusion of fly ash promoted the formation of more porous sodium aluminosilicate (N-A-S-H)-type gels, reducing the resistance to chloride ingress. Criado et a/. (2005) Fuel 84, 2048] studied the effect of curing conditions on the carbonation of the reaction products of alkali-activated fly ash systems. The atmospheric C0₂ reacted with the sodium present in the system, producing sodium bicarbonates instead, which reduces the amount of sodium available for the formation of N-A-S-H gel. The authors reported that the carbonation does not interrupt it. Contrarily, Fernandez-Jimenez et a/. (2007) [J. Mater. Sci. 42, 3055- 3065] reported the destruction of zeolite phases and de-alumination of N-A-S-H gel after immersion in HCI solution. Zhang et at. (2014) [Cem. Concr. Res. 64, 30-41] reported a decrease in the efflorescence rate due to the local reorganization and crystallization of N-A-S-H gels after hydrothermal curing. However, Skvara et at. (2012) [Ceram. -Silik. 56, 374-382], later reported that the alkalis (Na, K) can be almost completely leached from the investigated alkali-activated binder without compromising compressive strength. Leaching of a range of metals has been also found in works by the inventors, and so far, it has been impossible to achieve efficient immobilisation [Onisei et at. (2012) J. Haz. Mater. 205, 101-110; Iacobescu et a/. (2017) Front. Chem. Sci. Engin. 11, 317 - 327].

When properly designed, alkali activated binders can exhibit higher strengths than OPC-based concretes. Moreover, it is possible that alkali-activated binders are more durable and resistant to chloride, carbonate and sulphate ingression, due to their lower porosity and thus lower permeability [Duxson et at. (2007) J Mater Sci 42, 2917]. Being rather new systems, barriers do exist in the upscaling of alkali- activated concretes towards real-life applications.

Hybrid cements: a blend of solids mixed with an alkali-source and OPC: A possible way to reduce the amount of alkalis necessary to activate the precursor is by combining alkalis, OPC and the residue. This family of binders, often called hybrid, could incorporate a high content of industrial residues and needs only a small content (i.e. max 30 wt%) of OPC. Hybrid cements attract considerable attention both from the scientific and industrial community, and are seen as a pragmatic step forward. The work pursued so far has focused on alkali-activated blast furnace slag, as high calcium source, and on metakaolin, fly ash, etc. as low-calcium sources [Garcia-Lodeiro et at. (2012) Rom. J. Mater. 42, 330-335]. Incinerator ashes and blast furnace slag, due to their mineralogical and chemical composition, were found less responsive to alkaline activation than fly ash and hence they require a clinker content of at least 40 wt% to obtain acceptable strength values [Garcia-Lodeiro et at. (2017) Waste and Biomass Valorization 8, 1433-1440].

In these systems, both the residue and the activators employed are crucial factors. This is simply reflecting the fact that the performance is dependent on both ingredients and their interaction, the pH being a determining parameter [Garcia- Lodeiro et al. (2015) in "Handbook of Alkali -Activated Cements, Mortars and Concretes" Woodhead publishing, Oxford. 19-47]. For instance, in OPC, the phases prevailing are C-S-H and CH, at a slightly alkaline activating environment. In the hybrid cements, where only a fraction is OPC and the most abundant source are the Si,Ca,AI-rich by-products, additional phases or hybrid phases could form. In most of these hybrid systems, the activator is typically NaOH solely, but a combination of Na-silicates (i.e. water glass) could also be used [Palomo et al. (2007) J. Mater. Sci. 42, 2958-2966]; therefore, Na could replace Ca and if Al is present, it could convert from traditional poorly-crystalline C-S-H, into gels like N- A-S-H or (N,C)-A-S-H. For the (N,C)-A-S-H to occur, high Ca and low Al contents need to be present. The (N,C)-A-S-H is formed due to the similar ionic radius and electronegative potential of Na and Ca ions; Ca replaces the Na ions via an ion exchange mechanism reminiscent of the ones observed in clay and zeolites, maintaining the three-dimensional structure of the (N,C)-A-S-H-type gel [Engelhardt & Michel (1987), High resolution solid state RMN of silicates and zeolites, John Wiley & Sons, New Delhi; Garcia-Lodeiro et al. (2010) J. Am. Ceram. Soc. 93, 1934-1940]. These phases need typically higher alkali concentrations. Fly ash systems generate primarily (N,C)-A-S-H and some (N,C)-S-H gels. No (N,C)-A-S-H gels were detected in incinerator waste systems as reported by Garcia-Lodeiro et al. (2017) [Waste and Biomass Valorization 8, 1433-1440].

Prior studies have shown that the co-precipitation of these two gels in hybrid cements is possible [Alonso & Palomo (2001) Materials Letters 47, 55-62. Yip et al. (2005) Cem. Conor. Res. 35, 1688-1697; Palomo et al. (2007) J. Mater. Sci. 42, 2958-2966], although recent research has revealed that the two products do not develop singly as two separate gels, but they interact, undergoing structural and compositional changes in the process [Garcia-Lodeiro et at. (2011) Cem. Concr. Res. 41, 23-931]. The use of other alkaline activators is also possible with implications on the reaction products. Na₂C03 retarded gel precipitation, favouring the formation of secondary phases such as gaylussite and AFm-type species. Nonetheless, a larger proportion of gel phase appeared to precipitate than in the system activated with the most common solutions containing either NaOH or N- silicates. Additional work confirmed that Portland cement hydration is affected by the alkaline content (OH- concentration) and the presence of soluble silica.

Many cementitious systems have now been studied, including : alkali-activated OPC and blast furnace slag cement, alkali-activated OPC and phosphorus slag cement, alkali-activated OPC and fly ash cement, alkali-activated OPC and blast furnace slag/steel slag cement, a I kali -activated OPC and blast furnace slag/fly ash cement and alkali-activated multiple components blended cements [Shi et at. (2011) Cement Concrete Res. 41, 750-763].

As already presented above, the work on Si,Ca,AI-rich formulations covers alkali- activated formulations without and with OPC, the latter referred to as hybrid. In the case of Fe-rich formulations, only alkali-activated formulations have been reported. From a scientific point of view this is not surprisingly, as Fe is known to have only limited participation in the hydration products of cement. In view of the above, one would expect indeed low reactivity. On the other hand though, Fe-rich residues are produced in high volumes, thus there is a social and industrial push to find applications. A possible success in developing Fe-rich durable, sustainable and safe-to-use binders would be a breakthrough.

SUMMARY OF THE INVENTION

This invention provides a way to upcycle Fe-rich streams towards a novel binder that is durable, sustainable and safe-to-use. This is achieved by applying a sophisticated blend design that comprises at least three ingredients, that being the Fe-rich glass or Fe-rich metallurgical slag, the Ca source and the alkali source. As a result, the formulations described herein exhibit unprecedented durability and resistance to a range of environments. In detail, the invention refers to a multicomponent binder, said binder comprising an Fe-rich glass or Fe-rich metallurgical slag as the main component along with Ordinary Portland Cement and/or other Ca-rich resources, mineral residues, a sulphate source, alkalis and additives as minor components. These binders have several technical advantages: they exhibit low shrinkage, good strength development, have low leaching of metals, present a high chemical resistance, high freeze-thaw resistance and good behaviour in the event of a fire. Moreover, they are sustainable, considering they are made of by-products while being recyclable, and in addition, have a low cost and can be produced industrially today, as all ingredients are commercially available.

The present invention solves the problems of the related art by providing a composition that is a self-levelling, vibrational or pressable binder mix, where the mix is a binder, mortar or concrete, that can be subsequently cured at a range of temperatures and pressures, including hydrothermal curing. This delivers materials exhibiting a compressive strength higher than 5 MPa after 1 day and higher than 20 MPa after 28 days with low shrinkage, excellent freeze-thaw and good fire-resistance, and very good heavy metal immobilisation. In the event slags have been used also as aggregates in the mortar and concrete, it results in a recyclable formulation, where the mortar or concrete can be produced again after crushing the original product, simply by adding alkalis. This kind of binder can greatly reduce the footprint of concrete and potentially be more economically competitive.

In accordance with the purpose of the invention, as embodied and broadly described herein, the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given as an illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

The present invention allows to use iron comprising waste material into building materials with high compressive strength. The present invention allows to use ingredients comprising heavy metals. As explained below in the experimental section, leaching of heavy metals in the compositions and methods of the present invention is low.

The present invention provide materials and methods wherein carbon dioxide emission is lower than for comparable prior art methods and processes.

The invention is further summarised in the following statements:

1. A binder for mortar or concrete comprising a mixture consisting of:

a) from 40 to 90 or 95 wt% of an Fe-rich glass or Fe-rich metallurgical slag, b) from 1 to 40 wt% of a calcium-rich additive, and

c) from 0.5 to 20 wt% of an alkali, wherein the sum of these percentages in the mixture, calculated on a dry basis, is 100%.

In the context of the present invention "Iron-rich" refers to a composition, which contains more than 30 wt%, 40 wt%, 50 wt%, 75 wt% or 90 wt% of Fe calculated as if present in the form of Fe₂03.

Herein the calcium-rich additive is typically a water soluble additive

The present invention relates to a binder comprising at least a) an Fe-rich glass or Fe-rich metallurgical slag, b) a calcium-rich additive, andc) an alkali. These three component a, b and c together are referred as the "mixture". Although the binder and its ingredient are typically in a dry form, the binder may also exists as a water containing composition when prepared for immediate use, or during the preparation of the binder water containing compounds may be used in its preparation.

For the calculation of concentrations in the mixture, wt% are given as if the component are present in dry form.

As an example 50 g dry Fe rich glass, a solution of 30 g calcium rich additive in 100 g water, and 20 g KOH in 500 ml water, refers regardless of it water content to a mixture "a) 50 wt% of an Fe-rich glass b) 30 wt% of a e calcium-rich additive, and c) 20 wt% of an alkali, calculated on a dry basis, wherein the sum of these percentages, calculated on a dry basis, in the mixture is 100%.

Equally other ingredients added to the mixture are calculated as if dry ingredient are added to a dry mixture.

In the above "calcium rich" refers to a composition, which contains more than 30 wt%, 40 wt%, 50 wt%, 75 wt% or 90 wt% of Ca in the form of CaO or calculated as if present in the form of CaO.

Within the condition that the sum of a + b + c should be 100 %, the amount of a) b) and c) can range independent from each other: - from 40, 50 or 60 to 70, 80, 90 or 95 wt% of an Fe-rich glass or Fe-rich metallurgical slag,

from 1, 2, 5, or 10 to 20, 30, 35 or 40 wt% of a calcium-rich additive, and

- from 0.5, 1, 2.5, or 5 to 10, 12.5, 15, 17.5 or 20 wt% of an alkali,

In the above, as well in any other part of the application, when ranges are recited, any range between a lower value and a higher value is envisaged.

2. The binder according to statement 1, wherein the Fe-rich glass or Fe-rich metallurgical slag in the mixture comprises between 5 or 10 and 100 wt% amorphous glass. In alternative embodiments Fe-rich glass or Fe-rich metallurgical slag in the mixture comprises between 5, 10, 20, 30, or 40 up 60, 70, 80, 90 or 100 wt% amorphous glass.

3. The binder according to statement 1 or 2, wherein the Fe-rich glass or Fe-rich metallurgical slag in the mixture comprises the following, when expressed as oxide:

-FeO/Fe₂C>₃: 30, or 40 up to 50, 60 or 70 wt%

- Si0₂: 10, 15, 20, or 30 up to 35, 40, 45 or 50 wt%,

- CaO: 0, 5, 10 or 15 up to 30, 35, 40 or 45 wt%,

- AI₂O₃: 0, 5, or 10 up to 20, 25, or 30 wt%,

- MgO: 0, 2.5, or 5 up to 15, 17.5 or 20 wt%,

- Ti0₂: 0, 2.5, or 5 up to 15, 17.5 or 20 wt%, and

- Na₂0: 0, 0.5, 1, 2, or 5 up to 7, 8, 9, or 10 wt%.

3b The binder according to any one of the previous statements, wherein the Fe- comprising glass or Fe-comprising metallurgical slag in the mixture comprises the following, when expressed as oxide:

-FeO/Fe₂C>₃: 30-70 wt%

- S1O2: 10-50 wt%,

- CaO: 0-45 wt%,

- Al₂0₃:0-30 wt%,

- MgO: 0-20 wt%,

- Ti0₂: 0-20 wt%, and

- Na₂0: 0-10 wt%.

4. The binder according to any one of statements 1 to 3, wherein the Fe-rich glass or Fe-rich metallurgical slag in the mixture comprises, in a concentration below 15 wt% when expressed as oxides, one or more elements selected from the group consisting of K, Na, Ba, Mn, Zn, Pb, S, Cu, P, N, Cr, As, Mo and V. In specific embodiments said concentration is between 0.5, 1, 2, 2.5 or 5 wt% up to 10, 12.5 or 15 wt%. This value refers to the total of oxides, if more than one oxide is present.

5. The binder according to any one of statements 1 to 4, wherein the iron oxidation state ratio Fe²⁺/Fe³⁺ in the Fe-rich glass or Fe-rich metallurgical slag in the mixture is between 0.05 and 50, or between 0.05 and 100. In specific embodiments said ratio is between 0.05, 0.1, 0.5, 1, 2. 5 or 10 up to 20, 30, 40, 45, 50, 60, 80, 90 or 100. Alternatively, the iron oxidation state ratio state ratio Fe²⁺/(Fe²⁺ + Fe³⁺) in the Fe-comprising glass or Fe-comprising metallurgical slag in the mixture is between 0.05 and 1. Such as between 0.05, 0.1, 0.2 up to 0.5, 0.75, 0.9 or 1.

6. The binder according to any one of statements 1 to 5, wherein the binder has been ground to a specific Blaine surface between 1000 and 20000 cm²/g. In specific embodiments said surface is between 1000, 2000, or 5000 up to 10000, 15000, 17500 or 20000 cm²/g.

7. The binder according to any one of statements 1 to 6, wherein the calcium-rich additive of the mixture, is one or more selected from the group consisting of:

- a CEMI, CEMII, CEMIII, CEMIV, CEMV in accordance with the EN 197, and preferably a CEMI 52.5R, or any one of the eight types of Portland cement according to ASTM C150: type I, type IA, type II, type IIA, type III, type IIIA, type IV, and type Va,

- cement clinker,

- CaO, Ca(OH)₂, CaCC>₃,

- calcium aluminate cement,

- calcium sulpho aluminate cement,

- calcium sulpho ferro aluminate cement, and,

- a blend of a material containing a monocalcium-, dicalcium- or tricalcium-silicate. These silicates can occur in any one of the known polymorphs.

8. The binder according to any one of statements 1 to 7, wherein the alkali in the mixture is a:

- a Li, Na or K salt or a mixture thereof. Examples are silicate, aluminate, carbonate, sulphate, sulphide, nitrate, nitride or hydroxide, or

- a non-pure alkali coming from a side stream. Examples are bauxite residue, cement kiln dust, aluminium anodizing sludge, and spent Bayer liquor.

9. The binder according to any one of statements 1 to 8, further comprising a soluble calcium-sulphate source, in an amount of up to 10 wt% of said mixture. Examples are natural anhydrous, anhydrous, hemihydrate, dihydrate, ye'elimite, calcium sulpho aluminate cements, calcium sulpho ferro aluminate cements, and combinations of thereof. In specific embodiments the soluble calcium-sulphate source is present from 0.5, 1, 2, or 5 up to 7, 8, 9, or 10 wt% of said mixture.

10. The binder according to any one of statements 1 to 9, further comprising one or more additives, in an amount of up to, 1, 2, 3 4 or 5 wt% of said mixture, selected from the group consisting of a superplasticizer of polycarboxylate ether- based (PCE) polymer, a polyamide (PA) polymer, and a melamine polymer. Examples of superplasticers iare Melflux™ (BASF), sikaplast™ (Sika), viscocrete™ (Sika), Fluvicon™ (Demula), Dynamon™ series (Mapei) and™ADVA (GCPAP).

11. The binder according to any one of statements 1 to 10, further comprising one or more additives in an amount of up to 5, 10, 15, 20, 25 or 30 wt% of said mixture, selected from the group consisting of ground granulated blast furnace slag (GGBFS), fly ash and bottom ash from power and waste incineration plants, burnt shale, calcined clay, glass waste, BOF slag, AOD slag, stainless steel slag, cement kiln dust, quartz, limestone, silica fume and bauxite residue.

12. The binder according to any one of statements 1 to 11, in admixture with one or more of sand, gravel, water and an aggregate, such as wood, or polymers with a specific particle size distribution in the ranges between 0 and 45 mm, such as from 0, 2.5, 5, 10, up to 20, 30, 35, 40 or 45 mm.

13. The binder with admixture according to statement 12, where the binder is a self-levelling, vibrational or pressable mix.

14. Use of a binder according to any one of statements 1 to 13, in the preparation of a mortar or concrete.

15. A mortar or concrete comprising a binder according to any one of statements 1 to 14.

In the below methods statements 16 to 29, the same subranges applies as specified in the above statements 1 to 15.

16. A method of preparing a binder for mortar or concrete comprising the step of mixing :

c) from 0,5 to 20 wt% of an alkali, calculated on a dry basis, wherein the sum of these percentages in the mixture, calculated on a dry basis is 100%.

Herein, the calcium rich additive is typically water soluble.

17. The method according to statement 16, wherein the Fe-rich metallurgical slag in the mixture originates from a high temperature industrial process, including pyro-metallurgical processes. 18. The method according to statement 16 or 17, wherein the Fe-rich glass or Fe- rich metallurgical slag in the mixture comprises between 5 or 10 and 100 wt% amorphous glass.

19. The method according to any one of statement 16 to 18, wherein the Fe-rich glass or Fe-rich metallurgical slag in the mixture comprises the following, when expressed as oxide:

- FeO/Fe₂C>₃: 30-70 wt%

- S1O2: 10-50 wt%,

- CaO: 0-45 wt%,

- AI₂C>₃:0-30 wt%,

- MgO: 0-20 wt%,

- T1O2: 0-20 wt%, and

- Na20: 0-10 wt%.

19b The method according to any one of the above method statements, wherein the Fe-comprising glass or Fe-comprising metallurgical slag in the mixture comprises the following, when expressed as oxide:

-FeO/Fe₂C>₃: 30-70 wt%

- S1O2: 10-50 wt%,

- CaO: 0-45 wt%,

- Al₂0₃:0-30 wt%,

- MgO: 0-20 wt%,

- T1O2: 0-20 wt%, and

- Na20: 0-10 wt%.

20. The method according to any one of statements 16 to 19, wherein the Fe-rich glass or Fe-rich metallurgical slag in the mixture comprises, in a concentration below 15 wt% when expressed as oxides, one or more elements selected from the group consisting of K, Na, Ba, Mn, Zn, Pb, S, Cu, P, N, Cr, As, Mo and V.

21. The method according to statement any one of statements 16 to 20, where elements in the Fe-rich glass or Fe-rich metallurgical slag are present as metals, oxides, sulphates, carbonates or silicates and can exhibit different oxidation states.

22. The method according to any one of statements 16 to 21, wherein the iron oxidation state ratio Fe²⁺/Fe³⁺ in the Fe-rich glass or Fe-rich metallurgical slag in the mixture is between 0.05 and 50 or 0.05 and 100. Alternatively, the iron oxidation state ratio state ratio Fe²⁺/(Fe²⁺+ Fe³⁺) in the Fe-comprising glass or Fe- comprising metallurgical slag in the mixture is between 0.05 and 1. Such as between 0.05, 0.1, 0.2 up to 0.5, 0.75, 0.9 or 1.

23. The method according to any one of statements 16 to 22, wherein the binder has been ground to a specific Blaine surface between 1000 and 20000 cm²/g.

24. The method according to any one of statements 16 to 23, wherein the calcium- rich additive of the mixture, is one or more selected from the group consisting of:

- cement clinker,

- CaO,

- Ca(OH)₂,

- CaCC>₃,

- calcium aluminate cement,

- calcium sulpho aluminate cement,

- calcium sulpho ferro aluminate cement, and,

- a blend of a material containing a monocalcium-, dicalcium- or tricalcium-silicate, in any one of the known polymorphs.

25. The method according to any one of statements 16 to 24, wherein the alkali in the mixture is a:

- a Li, Na and K salt or a mixture thereof such as a silicate, aluminate, carbonate, sulphate, sulphide, nitrate, nitride or hydroxide, or

- a non-pure alkali coming from side streams such as bauxite residue, cement kiln dust, aluminium anodizing sludge, and spent Bayer liquor.

26. The method according to any one of statements 16 to 25, further adding a soluble calcium-sulphate source, in an amount of up to 10 wt% of said mixture, such as natural anhydrous, anhydrous, hemihydrate, dihydrate, ye'elimite, calcium sulpho aluminate cements, calcium sulpho ferro aluminate cements, and combinations of the previous.

27. The method according to any one of statements 16 to 26, further adding one or more additives, in an amount of up to 5 wt% of said mixture, selected from the group consisting of a superplasticizer of polycarboxylate ether-based (PCE) polymer, a polyamide (PA) polymer, and a melamine polymer, such as Melflux™ (BASF), sikaplast™ (Sika), viscocrete™ (Sika), Fluvicon™ (Demula), Dynamon™ series (Mapei) or™ADVA (GCPAP). 28. The method according to any one of statements 16 to 27, further adding one or more additives in an amount of up to 30 wt% of said mixture, selected from the group consisting of ground granulated blast furnace slag (GGBFS), fly ash and bottom ash from power and waste incineration plants, burnt shale, calcined clay, glass waste, BOF slag, AOD slag, stainless steel slag, cement kiln dust, quartz, limestone, silica fume and bauxite residue.

29. The method according to any one of statements 16 to 28, further adding one or more of sand, gravel, water and an aggregate, such as wood, or polymers with a specific particle size distribution in the ranges between 1.00 and 45 mm.

30. The binder with admixture according to statement 29, where the binder is a self-levelling, vibrational or pressable mix.

31. A method of preparing a mortar or cement, comprising the steps of: -preparing a binder in accordance to the method of any one of statements 16 to 28 or providing a binder according to any one of statements 1 to 11,

- adding sand, gravel or an aggregate, such as wood, and polymers with a specific particle size distribution in the ranges between 1 and 45 mm.

32. The method according to statement 31, further adding water to obtain a self- levelling, vibrational or pressable mortar or cement.

Further embodiments of the invention are set forth in the following statements:

33. The main component (>50 wt%) of the binder is an Fe-rich glass or Fe-rich metallurgical slag that has the following properties:

- The material originates from a high-temperature industrial process

- The amorphous glass phase of the above mentioned material is between 10 and 100 wt%

-The chemical composition of the base elements in the bulk/amorphous glass phase is:

- Fe0/Fe₂03: 20-70 wt%SiC>2: 10-50 wt%

- CaO: 0-45 wt%

- AI₂C>₃:0-30 wt%

- MgO: 0-20 wt%

- Ti0₂: 0-20 wt%

- Minor elements below 15 wt% include but are not limited to K₂0, Na₂0, BaO, MnO, ZnO, PbO, SO3, S, Cu, Cu₂S, CuO, P₂Os, NiO,Cr₂C>₃, As₂C>₃, MoOx, VOx - In the list of major and minor elements above, the metals mentioned can be present as metals, oxides, sulphates, carbonates and silicates or other phases, and can exhibit different oxidation states

- The iron oxidation state ratio should be: Fe²⁺/Fe³⁺: 0.05-50

- Ground to a specific Blaine surface between 1000 and 20000 cm²/g

As the reactive water soluble calcium addition (<50 wt% of the dry binder) the following sources can be used :

- All CEMI-CEMV in accordance with the EN 197 and preferably a CEMI 52.5R

- Pure cement clinker

- CaO and Ca(OH)₂

- calcium aluminate cements

- calcium sulpho aluminate cements

- calcium sulpho ferro aluminate cements

- Any blend of materials that contains monocalcium-, dicalcium- or tricalcium- silicates, in any one of the known polymorphs

Mineral additions to fine tune certain properties can be added up to 30 wt% of the dry binder. This non exhaustive list of additions includes: ground granulated blast furnace slags (GGBFS), fly ash from power and waste incineration plants, burnt shale, calcined clays, glass waste, BOF slag, AOD slag, stainless steel slag, cement kiln dust, quartz, limestone, silica fume, bauxite residue, ...

Alkali's can be added to enhance the solubility of the Fe-rich glass or Fe-rich metallurgical slag in additions up to 15 wt% of the dry binder. The source of the alkalis can be any one of the following :

a single component or a mixture of all Li, Na and K salts such as: silicates, aluminates, carbonates, sulphates, sulphides, nitrates, nitrides and hydroxides. Non-pure alkalis coming from side streams such as: bauxite residue, cement kiln dust, aluminium anodizing sludge, as well as spent Bayer liquor.

The alkalis can be added after being dissolved in water, or as a dry powder Up to 10 wt% of a soluble calcium-sulphate source can be added. This non exhaustive list includes: natural anhydrous, anhydrous, hemihydrate, dihydrate, ye'elimite, sulpho aluminate cements, combinations of the previous.

Up to 5 wt% of additives such as a superplasticizer of polycarboxylate ether-based (PCE) polymer, polyamide (PA) polymer or melamine polymers can be added. Examples used during the development of the binder are: Melflux (BASF), sikaplast (Sika), viscocrete (Sika), Fluvicon (Demula), Dynamon series (Mapei), ADVA (GCPAP), among others. 34. The composition according to statement 33 where the composition is further being mixed with sand and gravel or other aggregates, being inorganic or organic in nature and including among others slags, wood, and polymers, with a specific particle size distribution in the ranges between 0 and 32 mm.

35. The composition according to statement 34, where after adding water in a water/binder ratio of 0.15 - 0.55, a composition for reinforcements, a composition for fillers, a composition for preformed parts, that composition being paste, mortar or concrete, is formed.

36. The composition according to any one of statements 33 to 35 , where the binder, mortar or concrete is a self-levelling, vibrational or pressable mix.

37. The composition according to any one of statements 33 to 36, where the composition is used for the fabrication of monoliths, that monolith being a building or a structural element, or any other shaped element, including aggregates.

38. The composition according to any one of the previous statements 33 to 37, where the compositions can be cured from -10 °C up to hydrothermal curing at 300°C, where the relative humidity ranges from 10 to 100 % and pressures from 1 to 85 bar.

39. The composition according to any one of statements 33 to 38 that can deliver compressive strengths between 5 MPa and 80 MPa after 1 day of room temperature curing, and between 20 MPa and 170 MPa after 28 days of room temperature curing.

40. The composition according to any one of statements 33 to 39 that can deliver compressive strengths between 5 MPa and 270 MPa after 1 day curing at elevated temperatures

41. The composition according to any one of statements 33 to 40 that can immobilize heavy metals such as As, V, Mo, Zn, Pb, Cr, Ni, Cu, Ba, Zn, Mn, Co, Cd, Sb, Sn and not only.

42. The composition according to any one of statements 33 to 41, that shows no or little damage after 50 freeze thaw cycles in air, water and water with de-icing salts.

43. The composition according to any one of statements 33 to 42 that shows low shrinkage, that being in the range of 2000 pm/m at 28 days of curing.

44. The composition according to statements 33 to 43, that can be easily recycled when crushed and milled after life service. The new binder when activated again delivers more than 50 % of the strength of the original binder due to the unreacted Fe-rich glass or Fe-rich metallurgical slag. 45. The composition according to any one of the previous statements 33 to 44 that can be considered in some cases as a low heat producing binder, thus able to be used in large volume applications.

46. The composition according to any one of the previous statements 33 to 45, that has a high chemical resistance against sulphates and acids due to the low amount of CSH and portlandite formed during the hardening process.

47. The composition according to any one of the previous statements 33 to 46, that can meet the requirements of the ISO 834-1, Eurocode 1 hydrocarbon fire curve and RWS curve for firing testing.

48. A binder comprising more than 50 wt% of an Fe-rich glass or Fe-rich metallurgical slag which originates from a high temperature industrial pyro- metallurgical process, wherein the amorphous glass phase of the binder is between 10 and 100 wt%,

-wherein the chemical composition of the base elements in the bulk/amorphous glass phase is

Fe0/Fe203: 20-70 wt%

Si0₂: 10-50 wt%

CaO: 0-45 wt%

AI₂C>₃ : 0-30 wt%

MgO: 0-20 wt%

Ti0₂: 0-20 wt%

-wherein the binder comprises minor elements below 15 wt% such as K₂0, Na₂0, BaO, MnO, ZnO, PbO, SO3, S, Cu, Cu₂S, CuO, P₂Os, NiO,Cr₂C>₃, As₂C>₃, MoOx or VOx,

-wherein metals in the binder can be present as metals, oxides, sulphates, carbonates and silicates or other phases, and can exhibit different oxidation states, -wherein the iron oxidation state ratio Fe²⁺/Fe³⁺ is between 0.05 and 50 and -wherein Ground to a specific Blaine surface is between 1000 and 20000 cm²/g.

49. The binder according to statement 48, comprising in a concentration of <50 wt% of the dry binder, a reactive water soluble calcium addition selected from one or more of the group consisting of:

- a CEMI-CEMV in accordance with the EN 197 and preferably a CEMI 52.5R,

- Pure cement clinker,

- CaO and Ca(OH)₂ ,

- calcium aluminate cements,

- calcium sulpho aluminate cements,

- calcium sulpho ferro aluminate cements, and, - a blend of a material containing a monocalcium-, dicalcium- or tricalcium-silicate, in any one of the known polymorphs.

50. The binder according to statement 48 or 49, comprising a mineral addition up to 30 wt% of the dry binder.

51. The binder according to statement 50, wherein the mineral addition is one or more selected from the group of ground granulated blast furnace slag (GGBFS), fly ash from power and waste incineration plants, burnt shale, calcined clay, glass waste, BOF slag, AOD slag, stainless steel slag, cement kiln dust, quartz, limestone, silica fume and bauxite residue.

52. The binder according to any one of statements 48 to 51, comprising an alkali in addition up to 15 wt% of dry binder.

53. The binder according statements 48 to 52, wherein the source of alkali is one or more selected from the group consisting of:

- a single component or a mixture of all Li, Na and K salts such as silicates, aluminates, carbonates, sulphates, sulphides, nitrates, nitrides and hydroxides, and-a non-pure alkali coming from side streams such as bauxite residue, cement kiln dust, aluminium anodizing sludge, and spent Bayer liquor,

wherein the alkali can be added after being dissolved in water, or as a dry powder.

54. The binder according to any one of statements 48 to 53, comprising up to 10 wt% of a soluble calcium-sulphate source, such as natural anhydrous, anhydrous, hemihydrate, dihydrate, ye'elimite, sulpho aluminate cements, and combinations of the previous.

55. The binder according to any one of statements 48 to 54, comprising up to 5 wt% of additives such as a superplasticizer of polycarboxylate ether-based (PCE) polymer, polyamide (PA) polymer or melamine polymers, such as Melflux (BASF), sikaplast (Sika), viscocrete (Sika), Fluvicon (Demula), Dynamon series (Mapei), ADVA (GCPAP).

56. The binder according to any one of the previous statements 48 to 55, where the binder is further being mixed with sand and gravel or other aggregates, such as wood, and polymers with a specific particle size distribution in the ranges between 0 and 32 mm.

57. The binder according to any one of the previous statements 48 to 56, where the binder is a self-levelling, vibrational or pressable mix.

58. The binder according to any one of the previous statements 48 to 57, which immobilizes heavy metals such as As, V, Mo, Zn, Pb, Cr, Ni, Cu, Ba, Zn, Mn, Co, Cd, Sb or Sn. 59. Use of a binder according to any one of statements 48 to 58, in the preparation of a mortar or concrete.

60. A mortar or concrete comprising a binder according to any one of statements 48 to 58.

Detailed description of embodiments of the invention

The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims.

Several documents are cited throughout the text of this specification. Each of the documents herein (including any manufacturer's specifications, instructions etc.) are hereby incorporated by reference; however, there is no admission that any document cited is indeed prior art of the present invention.

The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non- limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention. Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

It is to be noticed that the term "comprising", used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising means A and B" should not be limited to the devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

Similarly it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any one of the claimed embodiments can be used in any combination.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only. Each and every claim is incorporated into the specification as an embodiment of the present invention. Thus, the claims are part of the description and are a further description and are in addition to the preferred embodiments of the present invention. Each of the claims set out a particular embodiment of the invention. The following terms are provided solely to aid in the understanding of the invention.

It was found that the mineralogy of Fe-silicate slag has a profound influence on its reactivity for IP synthesis and the properties of synthesized mortars [Onisei, et a/. Proceedings of the 3rd International Slag Valorisation Symposium, Leuven, Belgium], explaining poor mechanical properties in earlier work [Bell & Kriven (2009) In "Mechanical Properties and Performance of Engineering Ceramics and Composites IV", John Wiley & Sons, 301-312]. More specifically, the reactivity can be boosted drastically by fast cooling (water quenching) of the slag after the metallurgical process, increasing the fraction of the amorphous component [Pontikes et at. (2013) Applied Clay Science 73, 93-102]. Mortars made using these fast cooled slags are seen to have compressive strengths that exceed those of OPC [Kriskova et al. (2015) J. Sustainable Metallurgy 1, 240-251]. The final Fe- rich IP was stipulated to contain Fe in the 3⁺ oxidation state [as already reported by Lemougna et al. cited above], even though most Fe-rich precursors contain Fe²⁺. Interestingly, recent results have shown that having Fe²⁺ in the precursor slag is actually preferred over Fe³⁺, leading to faster reaction kinetics and higher compressive strengths. Combining the results from Mossbauer and XANES renders an average 5-fold coordinated iron to be the most probable. Recent unpublished work reveals the atomic structure of Fe-rich binder using pair distribution function analysis. The mechanism of formation at the nano-scale was revealed by ex situ Mossbauer spectroscopy and in situ X-ray pair distribution function analysis and consists of 3 stages: dissolution of the precursor, formation of a Fe²⁺ silicate in which the Fe is homogeneously distributed in the silicate network and the oxidation to Fe³⁺ which leads to clustering of the Fe species on the nanoscale (clusters of 2- 5 FeO_x units). The strength of this resulting binder is mainly controlled by the chemical composition of the precursor, e.g. Fe/Ca molar ratio of the slag, while the kinetics are largely controlled by the chemistry of the activating solution, e.g. Si0₂/Na₂0 molar ratio of the silicate solution. The latter leads to the ability to decouple workability and mechanical performance and flexibly change them independently, which is a key benefit with respect to OPC. This paves the way to a more efficient material use in specific applications. The present invention describes a binder where at least 40 to50 wt% of the OPC is replaced by a finely ground Fe-rich glass or Fe-rich metallurgical slag. The remaining 50 to 60 wt% is reserved for additions that include OPC, alkali activators, sulphates, additives - such as plasticizers but not only restricted to that - and mineral additions. The obtained binder exhibits good early and late strength, durability in terms of freeze-thaw, acids and fire-resistance. This binder is also able to immobilize heavy metals that are frequently present in Pb, Cu, Zn, Ni,... metallurgy slags. When crushed and milled after life service, the products made out of it can be easily recycled by alkali activation while keeping at least 50 percent of the original strength, assuming there was at least 70 wt% total slag content in the initial product. By the combination of OPC and alkali activation, the cost and environmental footprint of the binder is kept as low as possible.

The term alkali activation implies the addition of an alkali source (hydroxide, carbonate, sulphate...) which leads to a subsequent enhanced reactivity and finally a water-insoluble, hard and dense material. The reaction products can be resembling the typical cement formulations, i.e. there is crystal growth. The term Inorganic Polymer, IP can be considered as a subfamily of the alkali activated materials. As defined by IUPAC, the term Inorganic Polymer defines a polymer or polymer network with a skeletal structure that does not include carbon atoms [http://goldbook.iupac.org/IT07515.html. Accessed 23/08/2017]. Moreover, the nature of the reaction products is not crystalline. In the present context, the term IP is used to describe not only the nature of the materials themselves but also the processing route of their synthesis. In particular, it is implied that IPs are formed after mixing the following components: a solid precursor, which is itself a mixture of solids, and an alkaline activator, which can be solid or in a solution. The resulting paste can set and harden usually at room temperature. The solid precursors most often used in the literature, are fly ash from coal combustion, metakaolin, as well as ground granulated blast furnace slag. With respect to the alkaline activators, these are usually concentrated solutions of Na,K-hydroxides and Na,K-silicates. In literature, other terms are also widely used, e.g. geopolymers, alkali-activated materials, low-temperature synthesized aluminosilicate glasses, etc. The reaction mechanism to form IPs involves dissolution of the solid precursor by alkaline hydrolysis, gelation and finally rearrangement and reorganisation, to a three- dimensional network. Fe-rich cements have been described in the literature but without any reference on hybrid cements: all publications are describing formulations that are Fe-rich, OPC-free. These can be categorised according to the kind of precursor. In a first group, the Fe-rich precursor is of analytical grade, and emphasis is placed on the atomic structure obtained. Perera et a/. (2007) [J. Eur. Ceramic Soc. 27, 2697- 2703] introduced Fe as FeO(OH) into a metakaolin-based geopolymer and concluded that the Fe occupies octahedral sites either as isolated ions or oxyhydroxide aggregates, suggesting that it was not incorporated into the geopolymer structure. Bell and Kriven [(2009) In "Mechanical Properties and Performance of Engineering Ceramics and Composites IV", John Wiley & Sons, 301-312.] synthesized Fe geopolymers from synthetic Fe₂C>₃.2SiC>₂ powder and potassium silicate solution to produce K₂0.Fe₂0₃.4Si0₂.13H₂0, but the resulting material was water-soluble and rubbery, requiring nearly one year to harden.

In a second group, the Fe-phase is present in ores or minerals. Lemougna et at. (2013) [J. Mater. Sci. 48, 5280-5286.] investigated the role of iron in the formation of geopolymers from volcanic ashes. Using ⁵⁷Fe Mossbauer spectroscopy, they identified both ferrous and ferric sites in the ashes, arising from the presence of both amorphous and crystalline ferroan forsterite, a mineral of the olivine-type, and augite, a mineral of the pyroxene-type. The authors suggest that upon alkali-activation, the Fe²⁺-bearing phase ferroan forsterite does not participate in, or interfere with, the geopolymer-forming reaction. However, a significant proportion of the Fe²⁺ in augite reacts with the alkali solution to form new ferric sites. Obonyo et al. (2014) [ Sustainability 6, 5535-5553], studied the suitability of two partially amorphous Fe-rich laterites as precursors for IPs. Different compositions including up to 35 wt% calcined laterite additions (for promoting reactivity) and river sand were prepared. The results (good mechanical properties, stability in water) indicated effective transformation and endurance of the newly formed products. It is believed that Fe plays a major role in this inorganic polymerization process, mainly because its accumulation in the clay matrix promotes the disorganization of kaolinite, the principal mineral of laterites, enhancing the dissolution and the later polymerization/ polycondensation.

In another most innovative group, Fe-phases are present in residues, either from metallurgical slags, and thus with residues originating from high temperature processes, or hydrometallurgical processes, and thus from relatively low temperatures. Regarding the slags, four subgroups can be identified depending on the precursor: Fe-Mg slags, Fe-Ni slags, secondary copper slags, and lead slags and secondary lead slags. Work on hydrometallurgical residues is also advancing, as evidenced by recent publications; a view on IPs with bauxite residue can be retrieved from Hertel et a/. (2016) [J. Sustain. Metall. 2, 394-404], and from the references cited therein. Considering that the research domain is vast, the works cited above are only indicative, in order to illustrate the intense activity. More information can be retrieved in the PhD thesis of Peys (2018) [Inorganic Polymers from Ca0-Fe0-Si02 Slag : Processing, Reaction Mechanism and Molecular Structure, KU Leuven] .

In the latter group, where Fe-phases are present in residues, metallurgical slags are most often used. It is known that metals such as Pb, Zn, Ni and Cu are most often produced by a pyrometallurgical process and substantial volumes of Fe-rich silicate slags emerge as side-streams. In general, these metallurgical slags mainly consist of iron, silica and aluminium oxide. A significant amount of CaO and/or MgO might also be present whereas also Ti0₂, Cr₂C>₃, MnO, Na₂0, K₂0, etc. can be found as minor components. They contain no more than 0.5% copper, 0.15% nickel, 0.03% cobalt, 1-1.5% zinc and 0.2% lead [Shi et al. (2006). "Alkali- Activated Cements and Concretes." Taylor & Francis, NY, USA.] but exceptions do exist where the metal content is higher. They can exist as semi-amorphous or as crystalline solids depending on the slag cooling conditions [Pontikes et a/. (2013) Applied Clay Science 73, 93-102] . The slags are generally mostly vitreous (90- 95%), around the fayalite domain (Fe₂Si0₄), with a small amount of crystalline phases. The iron oxidation state is mostly bivalent and the AI₂C>3 level is mainly below 10 wt%.

Slag bulk compositions can be plotted on ternary phase diagrams, [Piatak et al. (2015) Applied Geochemistry 57 , 236-266] . Studies that discussed slags produced from the extraction of Cu, in addition to possibly Pb and Zn, were grouped together as Cu (+ base metals) slag. Note however that there is not one ternary that is representative of 100% of the mass of all samples in a slag type. Since the ternaries are unlikely to depict all possible crystalline phases they can only be used to gain insight into the most likely crystalline phases.

Due to the fact that these Pb, Cu, Zn, Ni,... slags usually have a low content of CaO and MgO, they exhibit pozzolanic properties. Meaning that the material possesses little or no cementitious value, but in powder form and in the presence of water can chemically react with calcium hydroxide (Ca(OH)₂) to form compounds possessing cementitious properties. By increasing the CaO and MgO content, the materials can exhibit cementitious properties and can be used in the form of blended cements. As an alkali activated material, it has been reported that copper-slag cements exhibited compressive strengths from 40 to 80 MPa in both normal and steam curing conditions. However, no industrial application towards binders today permits the use of such slags.

EXAMPLES

Example 1. Characterisation of raw materials

The following raw materials have been used in the examples given below.

Table 1 : Chemical composition of main elements of the base raw materials

* GGBFS: ground granulated blast furnace slags

Table 2: XRD of the base raw materials

Table 3: Physical characterization of the base raw materials

All compressive strength values mentioned in the examples below were measured on 4x4x16 cm³ mortar samples. Example 2. Preparation and curing of a vibrational mortar

A mixture with the composition of the below table is designed.

Table 4: composition of vibrational mortar

After 5 minutes of mixing in a 3 litre Hobart mixer, a vibrational mortar was obtained. After curing at room temperature the compressive strength was: at 1 day: 14 MPa, at 7 days: 31 MPa, 28 days: 56 MPa, 90 days: 68 MPa. Shrinkage at 28 days was 620 pstrain. After 2 days curing at 60°C and 100 % RH, the compressive strength was 71 MPa. The carbon footprint of this mortar is 55 kg CC>2-eq/tonne, calculated using the Ecoinvent database (https://www.ecoinvent.org/database/ecoinvent-35/ecoinvent-35.html; accessed July 25, 2019) Example 3. Preparation and curing of a free flowing mortar (I)

A mixture with the composition of the below table is designed.

Table 5: composition of free flowing mortar

After 5 minutes of mixing in a 3 litre Hobart mixer, a free flowing mortar was obtained. After curing at room temperature the compressive strength was: at 1 day: 7 MPa, at 7 days: 18 MPa, 28 days: 43 MPa. After 2 days curing at 60°C and 100 % RH, the compressive strength was 41 MPa. The surface loss after 50 freeze thaw cycles with de-icing salts was 12 g/m². The carbon footprint of this mortar is 62 kg CC>2-eq/tonne, calculated using the Ecoinvent database.

Example 4. Preparation and curing of a free flowing paste(I)

A mixture with the composition of the below table is designed.

Table 6: composition of free flowing paste

After 5 minutes of mixing in a 3 litre Hobart mixer, a free flowing paste was obtained. Na-silicate mod 1.6 is a dry sodium silicate powder with a molar Si0₂ / Na₂0 ratio of 1.6. After curing at room temperature the compressive strength was: at 2 days: 21 MPa, 7 days: 43 MPa, 28 days: 86 MPa. After the standard Flemish column leaching test, the tested critical heavy metals in bold were above the limit that is acceptable for building materials in Flanders, Belgium:

Table 7: heavy metal leaching parameters

The leaching values of Ba, Cd, Cr, Co, Cu, Pb, Ni were far below the accepted limits. The 5 metals above are the most critical ones. Still, the materials made with this formulation will not meet the regulations and this is an example where the mix design developed herein will deliver superior performance; see Example 5. Example 5. Preparation and curing of a free flowing paste (II)

A mixture with the composition of the below table is designed.

Table 8: composition of free flowing paste

After 5 minutes of mixing in a 3 litre Hobart mixer, a free flowing paste was obtained. After curing at room temperature the compressive strength was: at 1 day: 5 MPa, 2 days: 12 MPa, 7 days: 27 MPa, 28 days: 42 MPa. The carbon footprint of this mortar is 97 kg CC>2-eq/tonne, calculated using the Ecoinvent database.

After the standard Flemish column leaching test, all tested critical heavy metals were below the detectable limit (BDL) that is acceptable for building materials in Flanders, Belgium.

Table 9: heavy metal leaching parameters

The leaching values of As, Sb, Ba, Cd, Cr, Co, Cu, Pb, Mo, Ni, V, Zn are now all below the accepted limits and are in most cases a factor 10 lower than in example 3. Example 6. Preparation and curing of a free flowing mortar (II)

A mixture with the composition of the below table is designed.

Table 10: composition of free flowing mortar

After 10 minutes of mixing in a 3 litre Hobart mixer a free flowing mortar was obtained. K-silicate mod 2.2 is a dry potassium silicate powder with a molar Si0₂ / l\la₂0 ratio (mod) of 2.2. After curing at room temperature the compressive strength was: at 1 day: 52 MPa, at 7 days: 128 MPa, 28 days: 153 MPa. After 2 days curing at 60°C and 100 % RH, the compressive strength was 181 MPa. The surface loss after 50 freeze thaw cycles with de-icing salts was 0 g/m².

Example 7 Preparation and curing of a free flowing mortar (III)

A mixture with the composition of the below table is designed.

Table 11 : composition of free flowing mortar

After 10 minutes of mixing in a 3 litre Hobart mixer a free flowing mortar was obtained. K-silicate mod 2.2 is a dry potassium silicate powder with a molar Si0₂ / Na₂0 ratio of 2.2. After curing at room temperature the compressive strength was: at 1 day: 68 MPa, 7 days: 113 MPa, 28 days: 141 MPa. After 2 days curing at 60°C and 100 % RH, the compressive strength was 161 MPa. The carbon footprint of this mortar is 109 kg C0₂-eq/tonne, calculated using the Ecoinvent database. The surface loss after 50 freeze thaw cycles with de-icing salts was 0 g/m². Example 8. Preparation and curing of a free flowing mortar (IV)

A mixture with the composition of the below table is designed.

Table 12: composition of free flowing mortar

After 5 minutes of mixing in a 3 litre Hobart mixer a free flowing mortar was obtained. After curing at room temperature the compressive strength was: at 1 day: 7 MPa, 7 days: 23 MPa, 28 days: 45 MPa. The carbon footprint of this mortar is 63 kg CC>2-eq/tonne, calculated using the Ecoinvent database.

Example 9. Preparation and curing of a free flowing mortar (V)

A mixture with the composition of the below table is designed.

Table 13: composition of free flowing mortar

After 5 minutes of mixing in a 3 litre Hobart mixer a free flowing mortar was obtained. After curing at room temperature the compressive strength was: at 1 day: 9 MPa, at 7 days: 19 MPa, 28 days: 48 MPa. The carbon footprint of this mortar is 66 kg CC>2-eq/tonne, calculated using the Ecoinvent database. Example 10. Preparation and curing of a free flowing mortar (V)

A mixture with the composition of the below table is designed.

Table 14: composition of free flowing mortar

After 5 minutes of mixing in a 3 litre Hobart mixer a free flowing mortar was obtained. After curing at room temperature the compressive strength was: at 1 day: 7 MPa, 7 days: 17 MPa, 28 days: 41 MPa. The carbon footprint of this mortar is 77 kg CC>2-eq/tonne, calculated using the Ecoinvent database. The shrinkage at 28 days was 480 pstrain.

Example 11. Preparation and curing of a free flowing mortar (VI)

A mixture with the composition of the below table is designed. Table 15: composition of free flowing mortar

After 5 minutes of mixing in a 3 litre Hobart mixer a free flowing mortar was obtained. After curing at room temperature the compressive strength was: at 1 day: 5 MPa, 7 days: 24 MPa, 28 days: 37 MPa. The carbon footprint of this mortar is 77 kg CC>2-eq/tonne, calculated using the Ecoinvent database.

Claims

1. A binder for mortar or concrete comprising a mixture consisting of:

a) from 40 to 95 wt% of an Fe-comprising glass or Fe-comprising metallurgical slag, wherein the glass or slag comprises more than 30 wt%

Fe, expressed as Fe₂C>₃,

b) from 1 to 40 wt% of a calcium comprising additive, wherein the additive comprises more than 30 wt% Ca, expressed as calcium oxide and c) from 0.5 to 20 wt% of an alkali,

wherein the sum of the percentages of a), b) and c) in the mixture, calculated on a dry basis, is 100%.

2. The binder according to claim 1, wherein the Fe-comprising glass or Fe- comprising metallurgical slag in the mixture comprises between 5 and 100 wt% amorphous glass.

3. The binder according to claim 1 or 2, wherein the Fe-comprising glass or Fe-comprising metallurgical slag in the mixture comprises, when expressed as oxide:

- 30-70 wt% Fe0/Fe₂0₃,

- 10-50 wt% Si0₂,

- 0-45 wt% CaO,

- 0-30 wt% AI₂C>₃,

- 0-20 wt% MgO,

- 0-20 wt% Ti0₂, and

- 0-10 wt% Na₂0.

4. The binder according to any one of claims 1 to 3, wherein the Fe-comprising glass or Fe-comprising metallurgical slag in the mixture comprises, in a concentration below 15 wt% when expressed as oxide, one or more elements selected from the group consisting of K, Na, Ba, Mn, Zn, Pb, S, Cu, P, N, Cr, As, Mo and V.

5. The binder according to any one of claims 1 to 4, wherein the iron oxidation state ratio Fe²⁺/Fe³⁺ in the Fe-comprising glass or Fe-comprising metallurgical slag in the mixture is between 0.05 and 100, or the iron oxidation state ratio Fe²⁺/ (Fe²⁺ + Fe³⁺) in the Fe-comprising glass or Fe- comprising metallurgical slag in the mixture is between 0.05 and 1.

6. The binder according to any one of claims 1 to 5, wherein the binder has a specific Blaine surface between 1000 and 20000 cm²/g.

7. The binder according to any one of claims 1 to 6, wherein the calcium- comprising additive of the mixture, is one or more selected from the group consisting of:

- cement clinker,

- CaO, Ca(OH)₂, CaCC>₃,

- calcium aluminate cement,

- calcium sulpho aluminate cement,

- calcium sulpho ferro aluminate cement, and,

- a blend of a material containing a monocalcium-, dicalcium- or tricalcium- silicate, in any one of the known polymorphs.

8. The binder according to any one of claims 1 to 7, wherein the alkali in the mixture is a:

- a Li, Na or K salt or a mixture thereof such as a silicate, aluminate, carbonate, sulphate, sulphide, nitrate, nitride or hydroxide, or

9. The binder according to any one of claims 1 to 8, further comprising a soluble calcium-sulphate source, in an amount of up to 10 wt% of said mixture, such as natural anhydrous, anhydrous, hemihydrate, dihydrate, ye'elimite, calcium sulpho aluminate cements, calcium sulpho ferro aluminate cements, and combinations thereof.

10. The binder according to any one of claims 1 to 9, further comprising one or more additives, in an amount of up to 5 wt% of said mixture, selected from the group consisting of a superplasticizer of polycarboxylate ether- based (PCE) polymer, a polyamide (PA) polymer, and a melamine polymer, such as Melflux™ (BASF), sikaplast™ (Sika), viscocrete™ (Sika), Fluvicon™ (Demula), Dynamon™ series (Mapei) or™ADVA (GCPAP).

11. The binder according to any one of claims 1 to 10, further comprising one or more additives in an amount of up to 30 wt% of said mixture, selected from the group consisting of ground granulated blast furnace slag (GGBFS), fly ash and bottom ash from power and waste incineration plants, burnt shale, calcined clay, glass waste, BOF slag, AOD slag, stainless steel slag, cement kiln dust, quartz, limestone, silica fume and bauxite residue.

12. The binder according to any one of claims 1 to 11, in admixture with one or more of sand, gravel, water and an aggregate, such as wood or polymers with a specific particle size distribution in the ranges between 0 and 45 mm .

13. The binder with admixture according to claim 12, where the binder is a self- levelling, vibrational or pressable mix.

14. Use of a binder according to any one of claims 1 to 13, in the preparation of a mortar or concrete.

15. A mortar or concrete comprising a binder according to any one of claims 1 to 13. 16. A method of preparing a binder for mortar or concrete comprising the step of mixing :

a) from 40 to 95 wt% of an Fe-comprising glass or Fe-comprising metallurgical slag, wherein the glass or slag comprises more than 30 wt% Fe, expressed as Fe₂03,

b) from 1 to 40 wt% of a calcium-comprising additive, wherein the additive comprises more than 30 wt% Ca, expressed as calcium oxide, and c) from 0.5 to 20 wt% of an alkali,

wherein the sum of the percentages of a) b) and c) in the mixture, calculated on a dry basis, is 100%.

17. The method according to claim 16, wherein the Fe-comprising metallurgical slag in the mixture originates from a high temperature industrial process, including pyro-metallurgical processes.

18. The method according to claim 16 or 17, wherein the Fe-comprising glass or Fe-comprising metallurgical slag in the mixture comprises between 5 and 100 wt% amorphous glass, or the iron oxidation state ratio Fe²⁺/ (Fe²⁺

+ Fe³⁺) in the Fe-comprising glass or Fe-comprising metallurgical slag in the mixture is between 0.05 and 1.

19. The method according to any one of claim 16 to 18, wherein the Fe- comprising glass or Fe-comprising metallurgical slag in the mixture comprises the following, when expressed as oxide:

- 30-70 wt% Fe0/Fe₂03,

- 10-50 wt% S1O2,

- 0-45 wt% CaO,

- 0-30 wt% AI2O3,

- 0-20 wt% MgO,

- 0-20 wt% T1O2, and

- 0-10 wt% Na₂0. 20. The method according to any one of claims 16 to 19, wherein the Fe- comprising glass or Fe-comprising metallurgical slag in the mixture comprises, in a concentration below 15 wt% when expressed as oxides, one or more elements selected from the group consisting of K, Na, Ba, Mn, Zn, Pb, S, Cu, P, N, Cr, As, Mo and V.

21. The method according to any one of claims 16 to 20, where elements in the Fe-comprising glass or Fe-comprising metallurgical slag are present as metals, oxides, sulphates, carbonates or silicates and can exhibit different oxidation states.

22. The method according to any one of claims 16 to 21, wherein the iron oxidation state ratio Fe²⁺/Fe³⁺ in the Fe-comprising glass or Fe-comprising metallurgical slag in the mixture is between 0.05 and 100. 23. The method according to any one of claims 16 to 22, wherein the binder has been ground to a specific Blaine surface between 1000 and 20000 cm²/g. The method according to any one of claims 16 to 23, wherein the calcium- comprising additive of the mixture, is one or more selected from the group consisting of:

- cement clinker,

- CaO,

- Ca(OH)₂,

- CaCC>₃,

- calcium aluminate cement,

- calcium sulpho aluminate cement,

- calcium sulpho ferro aluminate cement, and,

The method according to any one of claims 16 to 24, wherein the alkali in the mixture is a:

The method according to any one of claims 16 to 25, further adding a soluble calcium-sulphate source, in an amount of up to 10 wt% of said mixture, such as natural anhydrous, anhydrous, hemihydrate, dihydrate, ye'elimite, calcium sulpho aluminate cements, calcium sulpho ferro aluminate cements, and combinations thereof.

The method according to any one of claims 16 to 26, further adding one or more additives, in an amount of up to 5 wt% of said mixture, selected from the group consisting of a superplasticizer of polycarboxylate ether-based (PCE) polymer, a polyamide (PA) polymer, and a melamine polymer, such as Melflux™ (BASF), sikaplast™ (Sika), viscocrete™ (Sika), Fluvicon™ (Demula), Dynamon™ series (Mapei) or™ADVA (GCPAP).

28. The method according to any one of claims 16 to 27, further adding one or more additives in an amount of up to 30 wt% of said mixture, selected from the group consisting of ground granulated blast furnace slag (GGBFS), fly ash and bottom ash from power and waste incineration plants, burnt shale, calcined clay, glass waste, BOF slag, AOD slag, stainless steel slag, cement kiln dust, quartz, limestone, silica fume and bauxite residue.

29. The method according to any one of claims 16 to 28, further adding one or more of sand, gravel, water and an aggregate, such as wood or polymers with a specific particle size distribution in the ranges between 1 and 45 mm .

30. A method of preparing a mortar or cement, comprising the steps of:

-preparing a binder in accordance to the method of any one of claims 16 to 28, or providing a binder according to any one of claims 1 to 10,

31. The method according to claim 30, further adding water to obtain a self- levelling, vibrational or pressable mortar or cement.