System and method for producing concrete from brine

Abstract

System and method for producing a plurality of brine streams for use in producing concrete, comprising a selected brine stream production system configured to produce a monovalent and a polyvalent bri

Description

TECHNICAL FIELD

[0001] The present disclosure is directed to systems and methods for producing a plurality of brine streams for use in producing concrete. In addition, the present disclosure is directed to systems and methods for producing concrete from brine, in particular, though not exclusively, for producing 3D printable concrete using brine generated by seawater desalination plants. BACKGROUND

[0002] Desalination of seawater is a widely used method to produce drinking water in arid regions of the world. Such desalination processes produce brine as a byproduct, also known as reject brine. This is often disposed of into aquatic environments where it may negatively impact the environment. An environmentally sustainable technology to address this challenge is to valorise the brine into commercially valuable products instead of disposing it back into the sea.

[0003] The use of brine, brackish water or water from desalination plants for mixing with cement to form concrete is known - see for example US2023 / 0071790. However, such approaches have not been commercialised as there are several limitations associated with these existing approaches. Firstly, the resultant concrete generated by such processes sets very quickly (has a viscosity that rapidly increases once the brine is combined with the cement). This can place restrictions on the location of where the concrete is to be used as well as how the concrete is to be set. Furthermore, there are various components in brine which cause cracks and weak structure to the concrete object.

[0004] Other approaches which give better results, in terms of the viscosity and structure of the concrete object created from such concrete, are known such as that described in US 11,655,187. However, these approaches de not use brine and so do not provide environmentally sustainable technologies.

[0005] The present disclosure seeks to address at least some of these concerns. SUMMARY OF THE DISCLOSURE

[0006] The present disclosure seeks to use brine generated by seawater desalination instead of water in the production of concrete, including 3D (three-dimensional) printable concrete as well as conventional concrete, in order to reduce the use of concrete ingredients such as fresh / drinking water and cement. The reduction of cement advantageously would result in the production of environmentally friendly ‘green' concrete.

[0007] In order to provide printable concrete, it is desired to provide a concrete composition where the reaction time of the brine and the cement needs to be appropriate so as to allow the viscosity of the concrete mixture to increase at a slower rate than prior art compositions. Thus, when used in 3D printing, this prevents the concrete mixture from blocking up the nozzle of a 3D concrete printer. Furthermore, such a solution ideaHy has improved flowability, workability, buildability, dynamic yield and efficient setting time suitable for 3D printing of the concrete.

[0008] The disclosure is also directed to providing concrete which does not suffer from the characteristic limitations of the prior art methods. In this regard, it is to be noted that reinforcement of concrete has been attempted previously using different additives, including salt additives mixed with polymers or metals, water and brine. However, certain salt additives and brine components may lead to brittle concrete that would result in weak concrete structures. Such additives may also cause the concrete to set faster than the time required for the concrete to be processed and deposited by a 3D printer, thereby blocking (clogging up) the 3D printer.

[0009] Therefore, the present disclosure is directed towards systems and methods of producing ‘green’ concrete preferably with the optimal flowability, workability, buildability, and dynamic yield, as well as an efficient setting time to be used for 3D printing of concrete products.

[0010] There is disclosed herein systems and methods of desalinating seawater that produce brine streams of different mineral salt concentrations and use these streams for the production of a pumpable cementitious mixture (PCM) and pumpable brine mixture (PBM), which are combined to form a concrete mix that can be 3D printed. The use of a pumpable brine mixture with a controlled composition of selected minerals mitigates against the prior art problems of brittle concrete and enables the characteristics of the concrete mix to be made suitable for 3D printing.

[0011] A stream of low concentration brine can be used as a substitute for water when mixing with cement and a binder. Another stream or combination of streams of brine with a different concentration of a selected mineral salts can be used to create a curing accelerator of the process of generating and setting concrete.

[0012] By selecting a brine stream or combination of brine streams with a predetermined calcium ion concentration, the static yield stress and initial setting time of the concrete mix can be improved. Also, increasing the calcium ion concentration for example by increasing the proportion of high CaCb brine enhances the compressive strength of the concrete structure when tested at 28 days.

[0013] The present disclosure advantageously valorises the reject brine from desalination processes by using it in the production of 3D printable concrete, as well as conventional concrete. Applications of these concretes produced using reject brine include architectural structures, such as non-reinforced low-rise buildings and structural building components. Other applications include art installations and the fabrication of artificial synthetic reef elements. However, concrete produced with brine cannot be reinforced with steel, as the high chloride concentration in the brine would corrode the metal.

[0014] Some of the benefits of the systems and methods of producing concrete in accordance with the current disclosure, compared to concrete produced using potable water are: (i) improved quality and strength of the concrete resulting from including minerals in the brine, such as calcium, and optionally reducing minerals such as magnesium; (ii) reduction of the use of conventional concrete supplements such as cement mixed with calcium carbonate, as the brine contains high levels of calcium chloride which is found to be more beneficial for the compressive strength of the concrete than calcium carbonate; (iii) reduction of the volume of fresh / drinking water used for cement production; (iv) valorisation of the reject brine by repurposing a waste product and using it for a valuable and commercially viable product that is widely used in construction; and (v) improving the properties of the concrete mix such that it is suitable for 3D printing of concrete components of buildings, materials for restoration of coral reefs, as well as other commercial and decorative concrete products.

[0015] Commercialization of the techniques of the present disclosure enables ‘green’ concrete produced from brine as one of the main components of a concrete mix, and advantageously reduces CO? emissions by reducing the use of Portland cement, thus leading to a circular economy.

[0016] In a first aspect of the invention, there is provided a system for producing a plurality of brine streams for use in producing concrete, the system comprising: a selected brine stream production system configured to produce a monovalent brine and a polyvalent brine from seawater, and to produce at least one additional brine having a different mineral salt concentration to the monovalent brine and the polyvalent brine, wherein the monovalent brine and the at least one additional brine are for use in the production of concrete.

[0017] The selected brine stream production system may comprise a nanofiltration unit for separating the seawater into the monovalent brine and the polyvalent brine.

[0018] The system may further comprise a desalination system coupled to the selected brine stream production system.

[0019] The desalination system may comprise a reverse osmosis unit for processing a portion of the monovalent brine output from the nanofiltration unit into a reverse osmosis retentate and desalination water.

[0020] The selected brine stream production system may further comprise a brine concentration unit for processing the reverse osmosis retentate output from the reverse osmosis unit into a first additional brine.

[0021] The selected brine stream production system may further comprise at least one mineral settler and a boron removal unit for processing at least a portion of the first additional brine output from the brine concentration unit into a second additional brine.

[0022] The at least one mineral settler may comprise a calcium carbonate settler and a magnesium hydroxide settler.

[0023] The selected brine stream production system may further comprise at least one mineral removal unit for processing the polyvalent brine output from the nanofiltration unit into a third additional brine.

[0024] The at least one mineral removal unit may comprise a sulphate removal unit and a magnesium removal unit.

[0025] The monovalent brine, and the first additional brine or the second additional brine or the third additional brine or any combination thereof, may be used in the production of concrete.

[0026] In second aspect of the invention, there is provided a method for producing a plurality of brine streams for use in producing concrete, the method comprising: providing seawater to a selected brine stream production system to produce a monovalent brine and a polyvalent brine, and to produce at least one additional brine having a different mineral salt concentration to the monovalent brine and the polyvalent brine , wherein the monovalent brine and the at least one additional brine are for use in the production of concrete.

[0027] The seawater may be provided to a nanofiltration unit in the selected brine stream production system to separate the seawater into the monovalent brine and the polyvalent brine.

[0028] The method may further comprise processing a portion of the monovalent brine in a reverse osmosis unit comprised in a desalination system coupled to the selected brine stream production system to produce a reverse osmosis retentate and desalination water.

[0029] The method may further comprise processing the reverse osmosis retentate in a brine concentration unit to produce a first additional brine.

[0030] The method may further comprise processing at least a portion of the first additional brine in at least one mineral settler followed by a boron removal unit to produce a second additional brine.

[0031] The at least one mineral settler may comprise a calcium carbonate settler and a magnesium hydroxide settler.

[0032] The method may further comprise processing the polyvalent brine in at least one mineral removal unit to produce a third additional brine.

[0033] The at least one mineral removal unit may comprise a sulphate removal unit and a magnesium removal unit.

[0034] The monovalent brine, and the first additional brine or the second additional brine or the third additional brine or any combination thereof, may be for use in the production of concrete.

[0035] The first additional brine may have a higher concentration of mineral salts than the monovalent brine.

[0036] The second additional brine may comprise a low calcium chloride brine having a calcium chloride concentration in the range of from about 5,000 mg / L to about 100,000 mg / L.

[0037] The third additional brine may comprise a high calcium chloride brine having a calcium chloride concentration of at least about 200,000 mg / L.

[0038] The third additional brine may have a calcium chloride concentration in the range of from about 200,000 mg / L to about 350,000 mg / L.

[0039] In a third aspect of the invention, there is provided a system for producing concrete from brine, the system comprising: a selected brine stream production system configured to produce a monovalent brine and a polyvalent brine from seawater, and to produce at least one additional brine having a different mineral salt concentration to the monovalent brine and the polyvalent brine; and a concrete production unit into which at least a portion of the monovalent brine is fed together with a binder and an aggregate to produce a first mixture and into which the at least one additional brine is fed together with a binder and aggregate to produce a second mixture, the concrete production unit being configured to combine the first mixture and the second mixture to form concrete,

[0040] The selected brine stream production system may comprise a nanofiltration unit for separating the seawater into the monovalent brine and the polyvalent brine.

[0041] The system may further comprise a desalination system coupled to the selected brine stream production system.

[0042] The desalination system may comprise a reverse osmosis unit for processing a portion of the monovalent brine output from the nanofiltration unit into a reverse osmosis retentate and desalination water.

[0043] The selected brine stream production system may further comprise a brine concentration unit for processing the reverse osmosis retentate output from the reverse osmosis unit into a first additional brine.

[0044] The selected brine stream production system may further comprise at least one mineral settler and a boron removal unit for processing at least a portion of the first additional brine output from the brine concentration unit into a second additional brine.

[0045] The at least one mineral settler may comprise a calcium carbonate settler and a magnesium hydroxide settler.

[0046] The selected brine stream production system may further comprise at feast one mineral removal unit for processing the polyvalent brine output from the nanofiltration unit into a third additional brine.

[0047] The at least one mineral removal unit may comprise a sulphate removal unit and a magnesium removal unit.

[0048] The first additional brine or the second additional brine or the third additional brine or any combination of the additional brines may be used to produce the second mixture.

[0049] The concrete production unit may comprise a first mixer in which the first mixture is produced, a second mixer in which the second mixture is produced, and a third mixer in which the first mixture and the second mixture are combined to form the concrete.

[0050] The concrete production unit may comprise a 3D concrete printer.

[0051] The 3D concrete printer may comprise first and second progressive cavity pumps into which the first mixture and the second mixture output from the first and second mixers, respectively, are fed.

[0052] The 3D concrete printer may further comprise an in-line static mixer into which the first mixture and the second mixture are fed, via the first and second progressive cavity pumps, and combined to form concrete.

[0053] The 3D concrete printer may further comprise a nozzle into which the concrete is conveyed for the 3D printing of the concrete.

[0054] In a fourth aspect of the invention, there is provided a method for producing concrete from brine, the method comprising: a) providing seawater to a selected brine stream production system to produce a monovalent brine and a polyvalent brine, and to produce at least one additional brine having a different mineral salt concentration to the monovalent brine and the polyvalent brine; and b) conveying at least a portion of the monovalent brine to a concrete production unit and combining the monovalent brine with a binder and an aggregate to produce a first mixture; conveying the at least one additional brine to the concrete production unit and combining with a binder and an aggregate to produce a second mixture; and combining the first mixture and the second mixture in the concrete production unit to form concrete.

[0055] In a) the seawater may be provided to a nanofiltration unit in the selected brine stream production system to separate the seawater into the monovalent brine and the polyvalent brine.

[0056] a) may further comprise processing a portion of the monovalent brine in a reverse osmosis unit comprised in a desalination system coupled to the selected brine stream production system to produce a reverse osmosis retentate and desalination water.

[0057] a) may further comprise processing the reverse osmosis retentate in a brine concentration unit to produce a first additional brine.

[0058] a) may further comprise processing at ieast a portion of the first additionai brine in at ieast one minerai settier followed by a boron removal unit to produce a second additionai brine.

[0059] The at least one mineral settler may comprise a calcium carbonate settler and a magnesium hydroxide settler.

[0060] a) may further comprise processing the polyvalent brine in at least one mineral removal unit to produce a third additional brine,

[0061] The at least one mineral removal unit may comprise a sulphate removal unit and a magnesium removal unit.

[0062] The first additional brine or the second additional brine or the third additional brine or any combination of the additional brines may be conveyed to the concrete production unit to produce the second mixture.

[0063] The first additional brine may be conveyed to the concrete production unit to produce the second mixture.

[6064] The second additional brine and the third additional brine may be conveyed to the concrete production unit to produce the second mixture.

[0065] The second additional brine and the third additional brine may be combined in a ratio of approximately 3:2 to produce the second mixture.

[0066] The first mixture and the second mixture may be combined in an approximately 1:1 ratio to form the concrete.

[6067] The first additionai brine may have a higher concentration of mineral salts than the monovalent brine,

[0068] The second additional brine may be a low calcium chloride brine having a calcium chloride concentration in the range of from about 5,000 mg / L to about 100,000 mg / L.

[0069] The third additionai brine may be a high calcium chloride brine having a calcium chloride concentration of at least about 200,000 mg / L.

[6070] The third additional brine may have a calcium chloride concentration in the range of from about 200,000 mg / L to about 350,000 mg / L,

[0071] The monovalent brine for use in the production of the first mixture may be diluted with water, preferably the monovalent brine is diluted with water in an approximately 1:1 ratio.

[0072] The binder used to produce the first mixture may comprise one or more of Portland cement, calcined clay, ground-granulated blast-furnace slag or limestone powder.

[0073] The binder may comprise Portland cement, calcined clay and limestone powder.

[0074] The aggregate used to produce the first mixture may comprise sand, preferably wherein the sand is fine quartz

[0075] The aggregate to binder ratio in the first mixture may be approximately 1:1,

[0076] The monovalent brine to aggregate ratio in the first mixture may be approximately 0.28:1.

[0077] The first mixture may further comprise approximately 0.6 to 1 wt.% of a superplasticiser.

[0078] The first mixture may have a spread diameter of at least 150 mm in a slump flow test.

[0079] The first mixture may comprise from about 34 wt.% to about 52 wt.% sand, from about 17 wt.% to about 26 wt.% Portland cement, from about 10 wt.% to about 17 wt.% calcined clay, from about 5 wt.% to about 9 wt.% limestone powder, from about 10 wt.% to about 20 wt.% monovalent brine and from about 0.6 wt.% to about 1% wt.% superplasticiser, wherein the monovalent brine is diluted with water in an approximately 1:1 ratio.

[0080] The first mixture may comprise approximately 44 wt.% sand, 22 wt.% Portland cement, 14 wt.% calcined clay, 7 wt.% limestone powder, 12 wt.% monovalent brine and 1 wt.% superplasticiser, wherein the monovalent brine is diluted with water in an approximately 1:1 ratio.

[0081] The binder used to produce the second mixture may comprise limestone powder.

[0082] The aggregate used to produce the second mixture may comprise sand, preferably wherein the sand is fine quartz sand with a grain size of approximately 0.125 mm to 2 mm,

[0083] The aggregate to binder ratio in the second mixture may be approximately 1:1.

[0084] The at least one additional brine to binder ratio in the second mixture may be approximately 0.3:1.

[0085] The second mixture may comprise from about 34 wt.% to about 52 wt.% sand, from about 34 wt.% to about 52 wt.% limestone powder and from about 10 wt.% to about 20 wt.% of the at least one additional brine.

[0086] The second mixture may comprise approximately 44 wt.% sand, 44 wt.% limestone powder and 12 wt.% of the at least one additional brine.

[0087] The first mixture may be produced in a first mixer in the concrete production unit, the second mixture is produced in a second mixer in the concrete production unit, and the first mixture and the second mixture are combined in a third mixer in the concrete production unit to produce concrete.

[0088] The concrete production unit may comprise a 3D concrete printer and the first mixture and the second mixture output from the first and second mixers may be conveyed to first and second progressive cavity pumps, respectively, comprised in the 3D concrete printer.

[0089] The first mixture and the second mixture may be conveyed via the first and second progressive cavity pumps to an in-line static mixer comprised in the 3D concrete printer in which they may be combined to produce concrete.

[0090] The concrete may be deposited via a nozzle in the 3D concrete printer to form a 3D printed concrete product.

[0091] In a fifth aspect of the invention, there is provided a method for producing concrete from brine, the method comprising: combining a binder, an aggregate and a monovalent brine to produce a first mixture; combining a binder, an aggregate and least one additional brine having a different mineral salt concentration to the monovalent brine to produce a second mixture; and combining the first mixture and the second mixture to form concrete.

[0092] The monovalent brine may be obtained by processing seawater through a nanofiltration unit.

[0093] The monovalent brine for use in the production of the first mixture may be diluted with water, preferably the monovalent brine is diluted with water in an approximately 1:1 ratio.

[0094] A first additional brine may be used to produce the second mixture, the first additional brine having a higher concentration of mineral salts than the monovalent brine.

[0095] A second additional brine and a third additional brine may be used to produce the second mixture, the second additional brine having a low calcium chloride concentration in the range of from about 5,000 mg / L to about 100,000 mg / L and the third additional brine having a high calcium chloride concentration of at least about 200,000 mg / L.

[0096] The third additional brine may have a calcium chloride concentration in the range of from about 200,000 mg / L to about 350,000 mg / L.

[0097] The second additional brine and the third additional brine may be combined in a ratio of approximately 3:2 to produce the second mixture.

[0098] The first mixture and the second mixture may be combined in an approximately 1:1 ratio to form the concrete.

[0099] The binder used to produce the first mixture may comprise one or more of Portland cement, calcined clay, ground-granulated blast-furnace slag or limestone powder.

[0100] The binder may comprise Portland cement, calcined clay and limestone powder.

[0101] The aggregate used to produce the first mixture may comprise sand, preferably wherein the sand is fine quartz sand with a grain size of approximately 0.125 mm to 2 mm.

[0102] The aggregate to binder ratio in the first mixture may be approximately 1:1.

[0103] The monovalent brine to aggregate ratio in the first mixture may be approximately 0.28:1.

[0104] The first mixture further may comprise approximately 0.6 to 1 wt.% of a superplasticiser. [01 OS] The first mixture may have a spread diameter of at least 150 mm in a slump flow test.

[0106] The first mixture may comprise from about 34 wt.% to about 52 wt.% sand, from about 17 wt.% to about 26 wt.% Portland cement, from about 10 wt.% to about 17 wt.% calcined clay, from about 5 wt.% to about 9 wt.% limestone powder, from about 10 wt.% to about 20 wt.% monovalent brine and from about 0.6 wt.% to about 1% wt.% superplasticiser, wherein the monovalent brine is diluted with water in an approximately 1:1 ratio.

[0107] The first mixture may comprise approximately 44 wt.% sand, 22 wt.% Portland cement, 14 wt.% calcined clay, 7 wt.% limestone powder, 12 wt.% monovalent brine and 1 wt.% superplasticiser, wherein the monovalent brine is diluted with water in an approximately 1:1 ratio.

[0108] The binder used to produce the second mixture may comprise limestone powder.

[0109] The aggregate used to produce the second mixture may comprise sand, preferably wherein the sand is fine quartz sand with a grain size of approximately 0.125 mm to 2 mm.

[0110] The aggregate to binder ratio in the second mixture may be approximately 1:1.

[0111] The at least one additional brine to binder ratio in the second mixture may be approximately 0.3:1.

[0112] The second mixture may comprise from about 34 wt.% to about 52 wt.% sand, from about 34 wt.% to about 52 wt.% limestone powder and from about 10 wt.% to about 20 wt.% of the at least one additional brine.

[0113] The second mixture may comprise approximately 44 wt.% sand, 44 wt.% limestone powder and 12 wt.% of the at least one additional brine.

[0114] The concrete produced by the method may be suitable for 3D printing.

[0115] In a sixth aspect of the invention, there is provided a selected brine stream production system and desalination system for producing a plurality of brine streams for use in producing concrete, the system comprising: a nanofiltration unit for separating seawater into a monovalent brine and a polyvalent brine; a reverse osmosis unit for processing a portion of the monovalent brine output from the nanofiltration unit into a reverse osmosis retentate and desalination water; a brine concentration unit for processing the reverse osmosis retentate output from the reverse osmosis unit into a first additional brine; a calcium carbonate settier, a magnesium hydroxide settlerand a boron removal unit for processing at least a portion of the first additional brine output from the brine concentration unit into a second additional brine; a sulphate removal unit and a magnesium removal unit for processing the polyvalent brine output from the nanofiltration unit into a third additional brine; wherein the additional brines have different mineral salt concentrations to the monovalent brine and the polyvalent brine, and wherein the monovalent brine and any one or more of the additional brines are for use in the production of concrete.

[0116] In a seventh aspect of the invention, there is provided a method for producing a plurality of brine streams for use in producing concrete, the method comprising: providing seawater to a nanofiltration unit to separate the seawater into a monovalent brine and a polyvalent brine; processing a portion of the monovalent brine in a reverse osmosis unit to produce a reverse osmosis retentate and desalination water; processing the reverse osmosis retentate in a brine concentration unit to produce a first additional brine; processing at least a portion of the first additional brine in a calcium carbonate settier and a magnesium hydroxide settler followed by a boron removal unit to produce a second additional brine; processing the polyvalent brine in a sulphate removal unit and a magnesium removal unit to produce a third additional brine; wherein the additional brines have different mineral salt concentrations to the monovalent brine and the polyvalent brine, and wherein the monovalent brine and any one or more of the additional brines are for use in the production of concrete.

[0117] In an eighth aspect of the invention, there is provided a method for producing 3D printable concrete from brine, the method comprising: providing seawater to a nanofiltration unit to separate the seawater into a monovalent brine and a polyvalent brine; processing a portion of the monovalent brine in a reverse osmosis unit to produce a reverse osmosis retentate and desalination water; processing the reverse osmosis retentate in a brine concentration unit to produce a first additional brine; processing at least a portion of the first additional brine in a calcium carbonate settler and a magnesium hydroxide settler followed by a boron removal unit to produce a second additional brine; processing the polyvalent brine in a sulphate removal unit and a magnesium removal unit to produce a third additional brine; combining a binder, an aggregate, a superplasticiser and the monovalent brine to produce a first mixture; combining a binder, an aggregate and the first additional brine or a combination of the second additional brine and the third additional brine to produce a second mixture; and combining the first mixture and the second mixture to form concrete.

[0118] In a ninth aspect of the invention, there is provided a composition comprising approximately 44 wt.% sand, 22 wt.% Portland cement, 14 wt.% calcined clay, 7 wt.% limestone powder, 12 wt.% monovalent brine and 1 wt.% superplasticiser, wherein the monovalent brine is diluted with water in an approximately 1:1 ratio.

[0119] The monovalent brine may be obtained by processing seawater through a nanofiltration unit.

[0120] The diluted monovalent brine may have a composition as provided in Figure 8 column b).

[0121] In a tenth aspect of the invention, there is provided a composition comprising approximately 44 wt.% sand, 44 wt.% limestone powder and 12 wt.% brine,

[0122] The brine may have a composition as provided in Figure 9 column a).

[0123] The brine may have a composition as provided in Figure 9 column b).

[0124] In an eleventh aspect of the invention, there is provided a concrete mixture comprising the composition of any of paragraphs

[0118] to

[0120] and the composition of any of paragraphs

[0121] to

[0123] combined in an approximately 1:1 ratio,

[0125] The concrete mixture may be suitable for 3D printing.

[0126] In a twelfth aspect of the invention, there is provided a system for producing concrete from brine, the system comprising: a concrete production unit into which a monovalent brine is fed together with a binder and aggregate to produce a first mixture and into which at least one additional brine having a different mineral salt concentration to the monovalent brine is fed together with a binder and an aggregate to produce a second mixture, the concrete production unit being configured to combine the first mixture and the second mixture to form concrete.

[0127] The concrete production unit may comprise a first mixer in which the first mixture is produced, a second mixer in which the second mixture is produced, and a third mixer in which the first mixture and the second mixture are combined to form the concrete.

[0128] The concrete production unit may comprise a 3D concrete printer.

[0129] The 3D concrete printer may comprise first and second progressive cavity pumps into which the first mixture and the second mixture output from the first and second mixers, respectively, are fed.

[0130] The 3D concrete printer may further comprise an in-line static mixer into which the first mixture and the second mixture are fed, via the first and second progressive cavity pumps, and combined to form concrete.

[0131] The 3D concrete printer may further comprise a nozzle into which the concrete is conveyed for the 3D printing of the concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0132] Embodiments of the disclosure will now be described, by way of example, with reference to the accompanying drawings, in which:

[0133] Figure 1a is a block diagram overview of a system according to an embodiment of the present disclosure, showing a selected brine stream production system for producing a plurality of different brine streams for use in the production of concrete;

[0134] Figure 1b is a block diagram overview of a system according to another embodiment of the present disclosure, where the system comprises the selected brine stream production system shown in Figure la and a concrete production unit in which the brine streams are used in the production of two mixtures for concrete production;

[0135] Figure 1c is a block diagram overview of a system according to another embodiment of the present disclosure, comprising the selected brine stream production system and concrete production unit shown in Figure 1b, wherein the concrete production unit comprises a 3D printer for printing concrete structures;

[0136] Figure 2 is a block diagram showing the details of a system for producing a plurality of different brine streams for use in the production of concrete according to an embodiment of the present disclosure;

[0137] Figure 3a is a schematic overview of the various different brine streams and desalinated water that can be produced according to an embodiment of the present disclosure;

[0138] Figure 3b is a more detailed illustration of a method of producing a plurality of different brine streams, as well as desalinated water, according to an embodiment of the present disclosure;

[0139] Figure 3c is a block diagram overview of the system shown in Figure 2;

[0140] Figure 4 schematically shows a set-on-demand lab-scale 3D concrete printer (3DCP);

[0141] Figure 5a is a block diagram of various features of the set-on-demand lab-scaie 3DCP shown in Figure 4;

[0142] Figure 5b is a flowchart of the method of operation of the set-on-demand lab-scale 3DCP shown in Figures 4 and 5a;

[0143] Figure 6 is a table showing the compositions of brine streams according to various embodiments of the present disclosure;

[0144] Figure 7a is a table showing the weight percentages of aggregate used depending on the aggregate grain size according to various embodiments of the present disclosure;

[0145] Figure 7b is a table showing the weight percentages of components used in the binder and mortars according to various embodiments of the present disclosure;

[0146] Figure 8 is a table showing the compositions of two brine streams used in various embodiments of the present disclosure;

[0147] Figure 9 is a table showing the compositions and physical properties of two brine streams used in various embodiments of the present disclosure;

[0148] Figure 10 shows a method of producing concrete according to various embodiments of the present disclosure. DETAILED DESCRIPTION

[0149] Various exemplary embodiments and details are described hereinafter, with reference to the figures when relevant. It should be noted that the figures may or may not be drawn to scale and that elements of similar structures or functions are represented by like reference numerals throughout the figures. It should also be noted that the figures are only intended to facilitate the description of the embodiments. They are not intended as an exhaustive description of the disclosure or as a limitation of the scope of the disclosure. In addition, an illustrated embodiment needs not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced in any other embodiments even if not so illustrated, or if not so explicitly described.

[0150] The figures are schematic and simplified for clarity, and they merely show details which aid understanding of the disclosure, while other details have been left out. Throughout, the same reference numerals are used for identical or corresponding parts.

[0151] Figure 1a shows a schematic overview of an exemplary system 100 of the disclosure. Here a selected brine stream production system 106 is used to generate a plurality of different brine streams 104a / b / c / d having different concentrations of mineral salts. Some of the brine 104a output from the selected brine stream production system 106 is passed to a conventional desalination system 102 which generates a desalination brine 104. This desalination brine 104 is passed back to the selected brine stream production system 106 for further processing. One or more of the multiple different brine streams 104a / b / c / d output from the selected brine stream production system 106 can subsequently be used in the production of concrete, e.g. two, three or four of the streams can be used.

[0152] The desalination brine 104 described above refers to a brine produced by a desalination system 102. However, it will be understood that any brine stream output by the desalination system 102 and further processed by a subsequent system / unit as described herein is also a desalinated brine. In embodiments of the disclosure wherein the desalination system 102 comprises a reverse osmosis unit that generates a desalination brine 104, the output of the desalination system 102 is referred to herein as a “reverse osmosis (RO) retentate”. This will be furtherdescribed below in reference to Figure 2.

[0153] The brine streams 104a / b / c / d output from the selected brine stream production system 106 can either be directly input to a concrete production unit 216 (as shown in Figure 1 b) or can be stored for use at a later time and / or in a different location. For example, in an embodiment, the concrete production unit 216 may be located adjacent the selected brine stream production system 106 and so the brine streams 104a / b / c / d are directed from the selected brine stream production system 106 directly to the concrete production unit. In another embodiment, the concrete production unit may be located far from the selected brine stream production system 106 and even on a different production site to the selected brine stream production system 106. In this other embodiment, the brine streams 104a / b / c / d may be stored and transported to the concrete production unit as necessary.

[0154] Figure 1b shows a block diagram of another embodiment of the system 100. As in the embodiment shown in Figure 1a, the system 100 herein comprises a selected brine stream production system 106 that is used to generate a plurality of different brine streams 104a / b / c / d having different concentrations of mineral salts. Some of the brine 104a output from the selected brine stream production system 106 is passed to a conventional desalination system 102 which generates desalination brine 104. This desalination brine 104 is passed back to the selected brine stream production system 106 for further processing. The brine streams 104a / b / c / d are subsequently used in the production of a first mixture 108 and a second mixture 110, wherein the first mixture 108 and the second mixture 110 further comprise binding materials (binders), which for the first mixture 108 may include cement. In an embodiment, brine stream 104a is used in the production of the first mixture 108 and one or more of brine streams 1Q4b / c / d are used in the production of the second mixture 110, The first mixture 108 and the second mixture 110 are mixed together in a concrete production unit 216 to produce concrete (also referred to herein as a concrete mixture). The concrete mixture can be used in the production of mouldable concrete products or printable concrete products. Therefore, the physical properties of the first mixture 108 and the second mixture 110 may be such that they are suitable for use in a printer of concrete structures, such as a 3D printer, e.g. the mixtures may be pumpable through the various components of the 3D printer, such as the nozzle, by virtue of having an appropriate viscosity and flowability. Accordingly, where the first and second mixtures 108, 110 are to be used in a 3D printer, they are also referred to herein as pumpable mixtures. This is further discussed below with reference to Figure 1c.

[0155] Figure 1c shows a block diagram of another embodiment of the system 100, wherein the concrete production unit 216 comprises a 3D printer 112. In this embodiment, the first mixture 108 may also be referred to as a pumpable cementitious mixture (PCM) and the second mixture 110 may also be referred to as a pumpable brine mixture (PBM). As described above for Figure 1b, the PCM 108 and the PBM 110 further comprise binding materials (binders), which for the PCM 108 may include cement. In an embodiment, brine stream 104a is used in the production of the PCM 108 and one or more of brine streams 104b / c / d are used in the production of the PBM 110. The PCM 108 and the PBM 110 are mixed together in the 3D printer to produce a printable concrete mixture that can be used to print concrete structures / products.

[0156] Figure 2 shows in more detail a selected brine stream production system 106 for the production of selected brine streams 104a / b / c / d for use in concrete production, for example in the production of mouldable concrete or printable concrete, according to an embodiment of the present disclosure. This figure also shows how the desalination system 102 and the selected brine stream production system 106 are integrated with each other.

[0157] The selected brine stream production systems 106 comprises a nanofiltration system / unit 202, a brine concentration unit 206, minerai settiers 208, a boron removal unit 210, and mineral removal units 212, 214. The desalination system 102 is coupled to and integrated with the selected brine stream production system 106 as shown, and comprises a reverse osmosis unit 204. The desalination and selected brine stream production systems 102, 106 produce selected brine streams 104a / b / c / d which are then used in the production of concrete and desalinated water.

[0158] In the current embodiment shown in Figure 2, seawater 200 is treated through the nanofiltration system / unit 202, which separates it into a nano-filtered monovalent permeate 104a comprising monovalent ions (also referred to herein as a monovalent brine, a monovalent brine stream, or a 3-1 reverse osmosis (RO) feed brine), and a polyvalent brine 220 comprising polyvalent ions. At least a portion of the monovalent permeate 104a is sent for concrete production, for example in a concrete production unit 216, to be used as mixing water for cement. The portion of the monovalent permeate 104a output / recovered for concrete production can also be referred to as stream #1 3-1 RO feed brine and can be diluted with water, which may be any suitable water including tap water or desalinated water, as is described in further detail below.

[0159] A portion of the nano-filtered monovalent permeate 104a can be further processed through the desalination system 102 comprising a reverse osmosis (RO) unit 204, to produce desalinated water 218 and a desalination brine 104, also referred to herein as a reverse osmosis (RO) retentate. Due to the separation of the desalinated water 218 from the monovalent permeate 104a input to the RO unit 204, the RO retentate 104 has a higher mineral salt concentration than the monovalent permeate 104a.

[0160] The RO retentate 104 can be further processed in the brine concentration unit 206, to produce a first additional brine 104b. In an embodiment of the disclosure, the brine concentration unit 206 comprises a mechanical vapour recompression (MVR) concentration unit. The first additional brine 104b, can therefore also be referred to as an MVR brine or a concentrated MVR brine. The mineral salt concentration of the MVR brine 1Q4b is higher than the mineral salt concentration of the RO retentate 104 and thus is also higher than the mineral salt concentration of the monovalent permeate 104a. At least a portion of the MVR brine 104b may be output for concrete production, for example in a concrete production unit 216, and this portion of MVR brine 104b may also be referred to as stream #2 concentrated MVR brine.

[0161] At least a portion of the MVR brine 104b may be further processed in one or more mineral settlers 208, which in an embodiment comprises calcium carbonate and magnesium hydroxide settlers, followed by the boron removal unit 210 to produce a second additional brine 104c. The second additional brine 104c may also be referred to as low CaCb brine or stream #3 low CaCh brine. The concentration of CaCb in this brine is typically in the range of from about 5,000 mg / L to about 100,000 mg / L, suitably from about 20,000 mg / L to about 80,000 mg / L, suitably from about 40,000 mg / L to about 60,000 mg / L. This second additional brine 104c is output for use in concrete production.

[0162] The polyvalent brine 220 may be processed in the selected brine stream production system 106 to generate a third additional brine stream 104d. In particular, the polyvalent brine 220 may be processed through at least one mineral removal unit to remove unwanted contaminants from the polyvalent brine 220 stream. In embodiments of the present disclosure, the polyvalent brine 220 is processed in a sulphate removal unit 212, followed by a magnesium removal unit 214, to produce the third additional brine 104d, also herein referred to as a high CaCh brine or stream #4 high CaCh brine. The concentration of CaCb in this brine is typically at least about 200,000 mg / L. Increasing the concentration of CaCh ions, results in a higher stiffness of the final concrete produced. Although this may be a favourable property of the final concrete, in embodiments wherein the concrete is generated in a 3D printer and used to print concrete structures, too high a concentration of CaCh ions may adversely affects the printing of the concrete. For example, the concrete mixture generated in the 3D printer may be too stiff to be printed and may result in a blockage of the printer. Therefore, in embodiments where the concrete mixture is generated in a 3D printer, and the high CaCb brine 104d is used in the production of the concrete mixture, the concentration of CaCL in the high CaCh brine 104d is typically in the range of from about 200,000 mg / L to about 350,000 mg / L, and suitably from about 200,000 mg / L to about 260,000 mg / L.

[0163] Figure 3a shows an exemplary method used in this system 100 to produce the various brine streams 104a / b / c / d from seawater using the desalination and selected brine stream production systems 102, 106. The seawater 200 is input to the selected brine stream production system 106, which is integrated with the desalination system 102, as described above, to produce a plurality of brine streams 104a / b / c / d and desalinated water 218. As described above, up to four different brine streams can be produced for use in the production of concrete. It is possible to produce fewer brine streams, for example one, two or three brine streams by stopping the process at a chosen point. For example, it is possible to produce solely the monovalent permeate 104a for use in the production of concrete by stopping the process after seawater nanofiltration. Also, for example, it is possible to produce solely the monovalent permeate 104a and the third additional brine 104c, without the need to use the desalination system 102. Instead of stopping the process at a certain point, it is possible to produce all four brine streams as described above and then to simply select which ones are to be used in concrete production. Any one or more of the brine streams can be selected for use in the production of concrete. In certain embodiments, the monovalent permeate 104a is used in the production of concrete, and one or more of the first, second or third additional brine streams 104b / c / d is also used in the production of concrete. In certain embodiments, the monovalent permeate 104a and the first additional brine 104b are used in the production of concrete. In certain embodiments, the monovalent permeate 104a, the second additional brine 104c and the third additional brine 104d are used in the production of concrete,

[0164] Figure 3b shows a flow diagram of the method of Figure 3a in more detail. In a first step, seawater is treated, at Step 302, using nanofiltration to produce a nano-filtered monovalent brine and a polyvalent brine.

[0165] A portion of the monovalent brine is output for concrete production (stream #1 3-1 RO feed brine) and a portion is subsequently processed, at Step 308, in a reverse osmosis unit to produce desalinated water and a reverse osmosis retentate,

[0166] The reverse osmosis retentate is subsequently processed, at Step 310, in a brine concentration unit to produce a first additional brine, also referred to herein as a concentrated mechanical vapour recompression (MVR) brine.

[0167] A portion of the MVR brine is output for concrete production (stream #2 concentrated MVR brine) and a portion is then processed, at Step 312, in calcium carbonate and magnesium hydroxide settlers.

[0168] The output from the calcium carbonate and magnesium hydroxide settlers is subsequently processed, at Step 314, in a boron removal unit to produce a second additional brine, also referred to herein as stream #3 low CaCh brine, which is output for concrete production.

[0169] The polyvalent brine output from the nanofiltration step is processed in a first mineral settler to remove, at Step 304, sulphate.

[0170] Subsequently, the output from the first mineral settler is processed in a second mineral settler to remove, at Step 306, magnesium to produce a third additional brine, also referred to herein as stream #4 high CaCb brine, which is output for concrete production.

[0171] Steps 304 and 306 may occur simultaneously to Steps 308 to 314. Alternatively, Steps 304 and 306 may occur prior to or subsequently to Steps 308 to 314. Accordingly, the numbering of these steps does not necessarily reflect the sequence in which they occur.

[0172] Figure 3c shows a block diagram overview of the selected brine stream production system 106 and desalination system 102 as shown in Figure 2.

[0173] Generally, as described herein, the brine streams 104a / b / c / d produced using the system and method of the disclosure, are used to produce two composites, namely a first mixture and a second mixture that are combined to form a concrete mixture. The first mixture and the second mixture further comprise at least one binder, which for the first mixture may include cement, and an aggregate. In an embodiment, brine stream 104a is used in the production of the first mixture and one or more of brine streams 104b / c / d are used in the production of the second mixture. The first mixture can also be referred to as a cementitious mixture and the second mixture can also be referred to as a brine mixture.

[0174] In embodiments where the first and second mixtures are to be used in or are suitable for use in a 3D printer for the production of 3D printable concrete, the first mixture can be referred to as a pumpable cementitious mixture (PCM) and the second mixture can be referred to as a pumpable brine mixture (PBM). The use of a particular combination of brine streams for the brine mixture / PBM produces concrete with different characteristics. The appropriate brine stream is selected to provide the appropriate characteristics for the particular application of the produced concrete.

[0175] For ease, the discussion that follows refers primarily to the first and second mixtures as the PCM and the PBM as it relates to mixtures that are particularly suitable for use in the 3D printing of concrete. However, these mixtures can also be used in the production of mouldable concrete.

[0176] Binding materials that may be used in the PCM and / or the PBM include CEM I 52.5 Portland cement (PC), calcined clay (CC), ground-granulated blast-furnace slag (GGBS) and limestone powder (LP). In an embodiment, the CC contains about 50% of metakaolin and is purchased from Argeco, France. Suitably, Portland cement (PC) is present in the PCM only. Suitably, the PCM may comprise a combination of Portland cement (PC), calcined clay (CC) and limestone powder (LP). Suitably, the PBM may comprise limestone powder (LP).

[0177] Suitably, where the binder for the PCM comprises a combination of Portland cement (PC), calcined clay (CC) and limestone powder (LP): the wt.% of PC in the binder may be in the range of from about 40 wt.% to about 60 wt.%, suitably from about 45 wt.% to about 55 wt.%, suitably from about 48 wt.% to about 52 wt.%; the wt. % of CC in the binder may be in the range of from about 25 wt.% to about 40 wt.%, suitably from about 28 wt.% to about 37 wt.%, suitably from about 30 wt.% to about 35 wt.%; and the wt.% of LP in the binder may be in the range of from about 12 wt.% to about 20 wt.%, suitably from about 15 wt.% to about 18 wt.%.

[0178] A suitable aggregate for use in the PCM and PBM is fine quartz sand with a grain size (grain diameter) of about 0.125 mm to about 2 mm. Depending on the grain size of the sand, the PCM and PBM composites / mortars described below comprise different weight percentages of sand. These weight percentages are given in Figure 7a.

[0179] To ensure a minimum flowability of the PCM, a superplasticiser can be added to the PCM mortar. Suitably, where the PCM mortar comprises a combination of PC, CC and LP as binder, together with sand, brine (brine stream 104a) and superplasticiser: the wt.% of sand in the mortar may be in the range of from about 34 wt.% to about 52 wt.%, suitably from about 37 wt.% to about 50 wt.%, suitably from about 40 wt.% to about 48 wt.%, suitably from about 42 wt.% to about 46 wt.%; the wt.% of PC in the mortar may be in the range of from about 17 wt.% to about 26 wt.%, suitably from about 20 wt.% to about 24 wt.%, suitably from about 21 wt.% to about 23 wt.%; the wt.% of CC in the mortar may be in the range of from about 10 wt.% to about 17 wt.%, suitably from about 12 wt.% to about 16 wt.%, suitably from about 13 wt.% to about 15 wt.%; the wt.% of LP in the mortar may be in the range of from about 5 wt.% to about 9 wt.%, suitably from about 6 wt.% to about 8 wt.%; the wt.% of brine in the mortar may be in the range of from about 10 wt.% to about 20 wt.%, suitably from about 11 wt.% to about 15 wt.%; and the wt.% of superplasticiser in the mortar may be in the range of from about 0.6 wt.% to about 1 wt.%.

[0180] Suitably, where the PBM mortar comprises binder (limestone powder), brine (one or more of brine streams 104b / c / d) and sand: the wt.% of binder in the mortar may be in the range of from about 34 wt.% to about 52 wt.%, suitably from about 37 wt.% to about 50 wt.%, suitably from about 40 wt.% to about 48 wt.%, suitably from about 42 wt.% to about 46 wt.%; the wt.% of brine in the mortar may be in the range of from about 10 wt.% to about 20 wt.%, suitably from about 11 wt.% to about 15 wt.%; and the wt.% of sand in the mortar may be in the range of from about 34 wt.% to about 52 wt.%, suitably from about 37 wt.% to about 50 wt.%, suitably from about 40 wt.% to about 48 wt.%, suitably from about 42 wt.% to about 46 wt.%.

[0181] In a test environment, the system and method described above were tested using ‘synthetic’ brine streams prepared based on the mass balance calculations of the brine streams produced at a brine management plant. Figures 6 and 8 are tables showing these synthetic brine streams 104a / b / c / d and these streams are expected to replicate brine streams 104a / b / c / d that would be produced at a full-scale desalination plant. These brine streams were selected because their compositions were the most suitable for 3D printed concrete (3DPC). Different concentrations of synthetic brine were prepared, corresponding to the different streams in Figure 3a, where the major limiting factor was the saturation point of the salt used. The change in concentrations was achieved by modifying the salt content in each of the prepared brines. The 3-1 RO feed brine (Stream #1) concentration was also changed to make it appropriate for the PCM; however this was achieved through dilutions with tap water or desalinated water as described in further detail below. Although tap water and desalinated water are appropriate diluting agents, tap water provides a lower cost option which is industrially beneficial. The results using these brine streams support the scaling up of the system to apply to brine streams created from full scale desalination plants, as described in further detail below in the Example.

[0182] In one embodiment, the PCM is developed using limestone calcined clay-based materials and is mixed with 3-1 RO feed brine (Stream #1) 104a, which acts as mixing water. The binder used in the PCM comprises 50 wt.% PC, 16.7 wt.% LP, and 33.3 wt.% CC. The aggregate-to-binder and mixing water-to-binder mass ratios are 1.0 (also referred to as 1:1) and 0.28 (also referred to as 0.28:1), respectively, for the PCM. In order to be pumped, the minimum flowability of the PCM is such that in a slump flow test a spread diameter larger than 150 mm is achieved. To satisfy this flowability requirement, 0.6 to 1 wt.% of polycarboxylate ether (PCE)-based superplasticizer (SP) is added to the PCM. In accordance with the wt.% of the binder components described above, the mortar for PCM contains approximately 44 wt.% sand, 22 wt.% PC, 14 wt.% CC, 7 wt.% LP, 12 wt.% 3-1 RO feed brine (Stream #1), and 1 wt.% superplasticizer. Figure 7b shows the weight percentages of the binder components and the relative weight percentages of the mortar components.

[0183] In a preferred embodiment, the mixing water for the PCM is a low concentration brine that has the composition of the ‘Target concentration water mixing brine’ shown in column b) of Figure 8. which shows the ion concentrations. This is achieved using the 3-1 RO feed brine (Stream #1) 104a, which has the composition shown in column a) of Figure 8, and diluting it with water, suitably tap water (preferable due to low cost) or desalinated water 218 generated from the desalination system 102. The final target concentration is achieved by combining 50% 3-1 RO feed brine (Stream #1) 104a and 50% tap water / desalinated water.

[0184] In an embodiment, the PBM is developed using a limestone-based mixture (LB) and is mixed with brine, which acts as a concrete accelerator. Exemplary compositions of the concrete accelerator brines are shown in Figure S - see columns c), e) and i). The brine-to-binder ratio used in the LB mixture is approximately 0.3 (also referred to as 0.3:1), where the binder is LP. The mortar forthe PBM comprises approximately 44% sand, 44% LP, and 12% brine. [018S] In an embodiment, the brine used as a concrete accelerator in the PBM is made with a combination of the Stream #3 low CaCI? brine 104c (see, for example, column i) of Figure 6) and the Stream #4 high CaCI? brine 104d (see, for example, column e) of Figure 6). At a certain proportion of 40% Stream #4 104d and 60% Stream #3 104c, the combination of the two streams outperforms using either stream individually and the exact composition of this combination is presented in column g) of Figure 6, which shows the mineral salt concentrations, and column b) of Figure 9, which shows the ion concentrations.

[0186] In an embodiment, the concrete accelerator in the PBM is made using Stream #2 concentrated MVR brine 104b, as this stream has favourable properties as a curing accelerator. Figure 6 column c) and Figure 9 column a) show the exact composition of the concentrated brine out of MVR. The choice of brine stream to be used as a concrete accelerator in the PBM is based on the required characteristics of the concrete. The combination of 40% Stream #4 104d and 60% Stream #3 104c, leads to stronger concrete than when using Stream #2. However, the use of Stream #2 as a concrete accelerator reduces the risks of corrosion and blocking of the 3D printer. Accordingly, the appropriate streams are selected for different required properties of the produced concrete.

[0187] In an embodiment, the brine mixture / PBM, the cementitious mixture / PCM and the concrete mix (concrete mixture) are produced according to the method 1000 shown in Figure 10.

[0188] In an embodiment, the cementitious mixture / PCM is produced by the following method. Tap water, 3-1 RO feed brine (Stream #1) 104a, or a combination thereof, and superplasticizer are added to a HOBART planetary mixing machine (first mixer). The binding materials and cement are then slowly added to the HOBART planetary mixing machine and mixed at a low speed of 60 rpm for 4 minutes (Step 1002). The mixing is stopped, and the bottom and walls of the container are scraped for 30 seconds, at Step 1004. At Step 1006, the mixing is resumed at a fast speed of 124 rpm for 2.5 minutes. The mixing is stopped to collect the cementitious mixture / PCM product at Step 1008.

[0189] in an embodiment, the brine mixture / PBM is produced by the following method. 40% high CaCl2+60% low CaCh (normal concentration brine) or Stream #2 concentrated MVR brine 104b are added to a HOBART planetary mixing machine (second mixer). Subsequently, the above-described binding materials are slowly added to the HOBART planetary mixing machine and mixed at a low speed of 60 rpm for 4 minutes (Step 1010). The mixing is stopped, and the bottom and wails of the container are scraped for 30 seconds, at Step 1012. At Step 1014, the mixing is resumed at a fast speed of 124 rpm for 2.5 minutes. The mixing is stopped to collect the brine mixture / PBM product at Step 1016.

[0190] In the embodiment shown in Figure 5a, which shows a 3D printer and is described in more detail later, the HOBART planetary mixing machines used to produce the PBM and PCM are directly connected to the progressive cavity pumps 504a, 504b comprised in the 3D printer.

[0191] In an embodiment, the concrete mix for use in a 3D printer is produced by the fallowing method. The PCM and PBM are separately conveyed to an in-line static mixer of a 3D printer, such as that shown in Figure 5a. The PCM and PBM are then mixed, at Step 1018, in the in-line static mixer. In Step 1020, the mixing is stopped and the resulting concrete mix is conveyed to a nozzle of the 3D printer from the in-line static mixer.

[0192] In an embodiment, the brine mixture and the cementitious mixture are used in the production of mouldable concrete according to the following method. The brine mixture and cementitious mixture are added to a HOBART planetary mixing machine (third mixer). The brine mixture and cementitious mixture are mixed, at Step 1018, at a low speed of 60 rpm for 30 seconds, in Step 1020, the mixing is stopped and the resulting concrete mix may be collected from the HOBART planetary mixing machine.

[0193] In a preferred embodiment, the cementitious mixture / PCM and the brine mixture / PBM added to the third HOBART planetary mixing machine or in-line static mixer are in a 1:1 mass ratio. By using this mass ratio, the Portland cement content in the final mixture is about 250 kg / m3, which is much lower than most of the proposed 3D printable cementitious materials, thereby supporting the environmentally friendly characteristics of this concrete.

[0194] The combination of the preferred PBM and preferred PCM in a 1:1 mass ratio, has the following associated advantages over the other embodiments described herein: (i) lowest dynamic yield stress and apparent viscosity of the PBM; (ii) suitable initial setting time of the final concrete mixture (45 to 90 minutes); (ill) highest static yield stress of the final concrete mixture; and (iv) a compressive strength of at least 30 MPa of the final concrete mixture at 28 days.

[0195] The calcium ion concentration has a significant impact on the static yield stress and initial setting time of the concrete mix, which are important factors for the buildability of 3D printable cementitious materials. In mixtures containing both high and low CaCb brine, increasing the proportion of high CaCb brine enhances the compressive strength at 28 days.

[0196] Turning now to the printing of concrete using a 3D printer. Figure 4 schematically shows a set-on-demand lab-scale 3D concrete printer (3DCP) with a corresponding block diagram in Figure Sa, and the associated method of operation in Figure Sb. The PCM and PBM composites used for 3D printing do not need to display high stiffness as required by a One-Component (IK) 3D printing process. The optimal stiffness and yield stress of the PCM and PBM for the 3D printer described herein, is achieved using the preferred embodiments of the PCM and PBM described in previously.

[0197] In an embodiment shown in Figure 4, a 3DCP 400 comprises at least two pumps 402a, 402b and an inline mixer 404. The two pumps 402a, 402b receive mixtures or materials such as a PCM or PBM as described in embodiments herein. The mixtures or materials are conveyed to the inline static mixer 404 to be combined (mixed) and printed to form 3D printed concrete structures 406.

[0198] In an embodiment shown in Figure 5a, the 3DCP 500 comprises three components: a three degree of freedom Computer Numerical Control (CNC) machine 502, two progressive cavity pumps 504a, 504b, and a customized printhead 506 attached to an in-line static mixer 508. The printhead 506 uses a twin-pipe system which comprises a metal pipe 510 with two inlets and a static in-line mixer 508 with 16 mixing baffles. The CNC machine 502, controlled by a computer 512 to control the 3D printer and in particular the movement of the print head, operates within a printing volume of 290 mm in height (the printing height is about 255 mm), 1100 mm in length, and 720 mm in width. Two commercial PFT Swing-M conveying pumps 504a, 504b (hopper volume of 38 litres) based on a rotor-stator configuration are employed. Two PFT material hoses (maximum pressure of 40 bar) with an inner diameter of 25 mm and a length of 5 m are used to connect the printhead and conveying pumps. The inner diameter of the pipe is 25 mm. Each baffle of the static in-line mixer 508 has a thickness of about 3 mm and a length of about 40 mm. Two adjacent baffles rotate in opposite directions. The printhead 506 is attached to a nozzle 514, which has an inner diameter of 25 mm.

[0199] In an embodiment shown in Figure 5b, the method of printing concrete is shown. Two pumpable composites, for example PBM and PCM, are mixed and conveyed, at Step 522, to the printhead using two progressive cavity pumps. The two composites are in-line mixed, at Step 524, in the printhead and deposited, at Step 526, via the nozzle to form a printed filament / layer.

[0200] Example of generating 3D printable concrete

[0201] In this example, a concrete mixture was generated and used to print concrete structures using a 3D printer. The concrete mixture was generated by combining a PBM and a PCM in a 1:1 ratio in an inline static mixer of a 3D printer. The 3D printer of this example comprised the set-on-demand labscale 3D concrete printer schematically shown in Figure 5a and described above. The method of operation is also described above in relation to Figure 5b.

[0202] The PCM was generated using binder, aggregate (sand), mixing water and superplasticizer. The binder comprised 50 wt.% PC, 16.7 wt.% LP, and 33.3 wt.% CC. The mortar for the PCM contained approximately 44 wt.% sand, 22 wt.% PC, 14 wt.% CC, 7 wt.% LP, 12 wt.% diluted 3-1 RO feed brine (Stream #1 - dikited as described below), and 1 wt.% superplasticizer, as described above.

[0203] The mixing water for the PCM was a iow concentration brine having the composition of the ‘Target concentration water mixing brine’ shown in column b) of Figure 8. This was achieved using Stream #1 3-1 RO feed brine 104a, which has the composition shown in column a) of Figure 8, and diluting it with tap water. The final target concentration was achieved by combining 50% Stream #1 3-1 RO feed brine 104a and 50% tap water.

[0204] The PBM was generated using an aggregate and a binder mixed with brine. The binder comprised 100 wt.% LP and the brine was used as a concrete accelerator. The mortar for the PBM comprised approximately 44% sand, 44% LP, and 12% brine.

[0205] Different brine compositions were tested for use as a concrete accelerator in the PBM. The different brine compositions included: Stream #2 concentrated MVR brine 104b (composition shown in column c) of Figure 6 and column a) of Figure 9); Stream #4 high CaCh brine 104d (composition shown in column e) of Figure S); Stream #3 low CaCh brine 104c (composition shown in column i) of Figure 6); and a mixture of 40% Stream #4 high CaCh brine 104d and 60% Stream #3 low CaCi? brine 104c (composition shown in column b) of Figure 9). The mixture of 40% Stream #4 high CaCh brine 104d and 60% Stream #3 low CaCh brine 104c is also referred to herein as 40% high CaCI;'+60% iow CaCh.

[0206] To determine the most favorable concrete accelerator, several physical characteristics of the PBM and the printed concrete were measured. The measured physical characteristics of the PBM include the dynamic yield stress and the plastic viscosity, and the results are shown in Table 1 below.

[0207] Table 1: Physical characteristics of the PBM using different brine streams as the concrete accelerator. Brine stream MVR High CaCb Low CaCh 40% High CaCl2+60% Low CaCI2 Dynamic Yield Stress (Pa) 2082.2 2343.2 1666.8 2021.2 Plastic Viscosity (Pas) 34.6 49.0 13.6 23.6 Requirement Low dynamic yield stress and plastic viscosity are beneficial to pumpability

[0208] The measured physical characteristics of the final concrete mixture include the initial setting time, the buildabiilty, the static yield stress and the compressive strength at 28 days. Buildability is an indicator of better durability of the final concrete mixture and therefore it was preferable that at least 10 layers of concrete could be stacked without collapsing, wherein each layer had an optimal width and length of about 30 mm. To ensure good durability of the final concrete mixture, the buildability was assessed by whether seventeen layers of concrete could be stacked without collapsing, wherein each layer had a length and width of from about 25 mm to about 50 mm, and a thickness of from about 12 mm to about 30 mm. These results are shown in Table 2 below.

[0209] Table 2: Physical characteristics of printed concrete using different brine streams as the concrete accelerator in the PBM. Brine stream Stream #2 MVR Stream #4 High Stream #3 Low CaCb CaCb 40% High CaCh+60% Low CaCb Initial Setting Time (min) 66.0 Less than 10 86.8 50.4 Requirement In the range of 45-90 min Buildability yes yes yes yes Requirement Stack 17 layers without collapsing Static Yield Stress (Pa) 84.9 Not measured due to fast 50.7 setting time 137.6 Requirement High static yield stress is good for buildability performance At least 50 Pa 28 Days Compressive Strength (MPa) 38.4 37.4 27.5 31.7 Requirement At least 30 MPa

[0210] The required ranges of physical characteristics for the PBM and the final concrete mixture have been given in Tables 1 and 2, respectively. Specifically, as the PBM has to be pumped in order to be conveyed to the inline static mixer of the 3D printer, the PBM has to meet pumpability requirements. These requirements include having relatively low dynamic yield stress and low plastic viscosity. From the results shown in Table 1, the lowest dynamic yield stress and plastic viscosity were achieved when using the Stream #3 low CaCh brine as the concrete accelerator in the PBM. However, relatively low dynamic yield stress and plastic viscosity values were also achieved when using either the 40% high CaCb+60% low CaCh brine mixture or the Stream #2 MVR as the concrete accelerator.

[0211] Furthermore, the final concrete mixture should ideally have an initial setting time in the range of 45 to 90 minutes. This requirement is fulfilled by using any of the Stream #2 MVR concentrated brine, the Stream #3 low CaCb brine or the mixture of 40% high CaCb+60% low CaCi?, as a concrete accelerator.

[0212] Additionally, any of the four streams tested as a concrete accelerator in the PBM satisfy the buildability requirement i.e. seventeen layers of concrete can be sequentially stacked without collapse of the printed structure.

[0213] Although the Stream #3 low CaCb brine resulted in the lowest dynamic yield stress and plastic viscosity of the PBM, the characteristics of the concrete mixture shown in Table 2 indicate that other brine streams resulted in a stronger concrete. For example, the compressive strength after 28 days of printing for Stream #3 did not meet the minimum requirement of having a value of at least 30 MPa (see Table 2). Static yield stress is strongly correlated with the buildability performance of the freshly printed concrete mixture and therefore a relatively high static yield stress of the concrete mixture results in a strong concrete and thus strong buildability. The highest static yield stress was achieved using the mixture of 40% high CaCb+60% low CaCb as concrete accelerator,

[0214] In addition, an increase in CaCb concentration resulted in a higher compressive strength after 28 days of printing, as indicated by the compressive strength values of the concrete mixtures produced using either the mixture of 40% high CaCb+60% low CaCb or the Stream #4 high CaCb brine compared to the Stream #3 low CaCb brine. However, the compressive strength was highest for concrete generated using the Stream #2 MVR concentrated brine, wherein Stream #2 MVR concentrated brine has a higher concentration of other salts than the mixture of 40% high CaCb+60% low CaCb as shown by the higher TDS value in Figure 9. [021S] The results shown in Tables 1 and 2 support that a combination of 40% Stream #4 W4d and 60% Stream #3 104c (40% high CaCb+60% low CaCb) outperforms using either stream individually to produce concrete. In particular, the use of only Stream #4 high CaCb led to a concrete mixture that settled too fast to be appropriate for 3D printing of concrete structures, even though the compressive strength of the printed concrete at 28 days was higher using Stream #4 high CaCb than for the combination of 40% Stream #4 W4d and 60% Stream #3 104c. Furthermore, using the mixture of 40% high CaCb+60% low CaCb resulted in a concrete mixture that had a higher static yield strength and compressive strength after 28 days compared to the concrete produced using Stream #3 low CaCb.

[0216] The results shown in Table 2 further support that concrete produced using the mixture of 40% high CaCb+60% low CaCb has a higher static yield strength but a lower compressive strength at 28 days compared to concrete produced using Stream #2 MVR concentrated brine. Accordingly, the appropriate streams can be selected depending on the required properties of the produced concrete.

[0217] Variations of the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain features are recited in mutually different dependent claims does not indicate that a combination of these claims cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

05 01 261. A method for producing concrete from brine, the method comprising:combining a binder, an aggregate and a monovalent brine to produce a first mixture;combining a binder, an aggregate and a first additional brine or a second additional brine or a third additional brine or any combination thereof to produce a second mixture, the additional brines having a different mineral salt concentration to the monovalent brine, the first additional brine having a higher concentration of mineral salts than the monovalent brine, the second additional brine having a low calcium chloride concentration in the range of from 5,000 mg / L to 100,000 mg / L and the third additional brine having a high calcium chloride concentration of at least 200,000 mg / L; andcombining the first mixture and the second mixture to form concrete.

2. The method according to claim 1, wherein the monovalent brine is obtained by processing seawater through a nanofiltration unit.

3. The method according to claim 1 or 2, wherein the monovalent brine for use in the production of the first mixture is diluted with water, preferably wherein the monovalent brine is diluted with water in an approximately 1:1 ratio, preferably wherein the diluted monovalent brine has a composition as provided in Figure 8 column b).

4. The method according to any of claims 1 to 3, wherein the third additional brine has a calcium chloride concentration in the range of from 200,000 mg / L to 350,000 mg / L.

5. The method according to any of claims 1 to 4, wherein the first additional brine is used to produce the second mixture.

6. The method according to any of claims 1 to 5, wherein the second additional brine and the third additional brine are used to produce the second mixture and are combined in a ratio of approximately 3:2 to produce the second mixture.

7. The method according to any of claims 1 to 6, wherein the first mixture and the second mixture are combined in an approximately 1:1 ratio to form the concrete.

8. The method according to any of claims 1 to 7, wherein the binder used to produce the first mixture comprises one or more of Portland cement, calcined clay, ground-granulated blast-furnace slag or limestone powder.

9. The method according to claim 8, wherein the binder comprises Portland cement, calcined clay and limestone powder.05 01 2610. The method according to any of claims 1 to 9, wherein the aggregate used to produce the first mixture comprises sand, preferably wherein the sand is fine quartz sand with a grain size of approximately 0.125 mm to 2 mm.

11. The method according to any of claims 1 to 10, wherein the aggregate to binder ratio in the first mixture is approximately 1:1.

12. The method according to any of claims 1 to 11, wherein the monovalent brine to aggregate ratio in the first mixture is approximately 0.28:1.

13. The method according to any of claims 1 to 12, wherein the first mixture further comprises approximately 0.6 to 1 wt.% of a superplasticiser.

14. The method according to claim 13, wherein the first mixture has a spread diameter of at least 150 mm in a slump flow test.

15. The method according to any of claims 1 to 14, wherein the first mixture comprises from 34 wt.% to 52 wt.% sand, from 17 wt.% to 26 wt.% Portland cement, from 10 wt.% to 17 wt.% calcined clay, from 5 wt.% to 9 wt.% limestone powder, from 10 wt.% to 20 wt.% monovalent brine and from 0.6 wt.% to 1 wt.% superplasticiser, wherein the monovalent brine is diluted with water in an approximately 1:1 ratio, preferably wherein the diluted monovalent brine has a composition as provided in Figure 8 column b).

16. The method according to any of claims 1 to 15, wherein the first mixture comprises approximately 44 wt.% sand, 22 wt.% Portland cement, 14 wt.% calcined clay, 7 wt.% limestone powder, 12 wt.% monovalent brine and 1 wt.% superplasticiser, wherein the monovalent brine is diluted with water in an approximately 1:1 ratio, preferably wherein the diluted monovalent brine has a composition as provided in Figure 8 column b).

17. The method according to any of claims 1 to 16, wherein the binder used to produce the second mixture comprises limestone powder.

18. The method according to any of claims 1 to 17, wherein the aggregate used to produce the second mixture comprises sand, preferably wherein the sand is fine quartz sand with a grain size of approximately 0.125 mm to 2 mm.

19. The method according to any of claims 1 to 18, wherein the aggregate to binder ratio in the second mixture is approximately 1:1.

20. The method according to any of claims 1 to 19, wherein the brine to binder ratio in the second mixture is approximately 0.3:1.

21. The method according to any of claims 1 to 20, wherein the second mixture comprises from 34 wt.% to 52 wt.% sand, from 34 wt.% to 52 wt.% limestone powder and from 10 wt.% to 20 wt.% brine.

22. The method according to any of claims 1 to 21, wherein the second mixture comprises approximately 44 wt.% sand, 44 wt.% limestone powder and 12 wt.% brine.

23. The method according to any of claims 1 to 22, wherein the concrete produced by the method is suitable for 3D printing.05 01 26

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