Mould for curing precursor by carbonation and method for producing carbonate bonded article using such mould

Abstract

The present invention relates to a mold (1, 100, 101, 102) for curing a precursor by carbonation comprising a reaction compartment (2) configured to receive and cure the precursor, the reaction compartment (2) comprising a liquid impermeable wall (3) wherein the liquid impermeable wall (3) is permeable to CO2 such that CO2 is allowed to be supplied to the precursor through the wall (3) while preventing liquid water from escaping through the wall (3). The invention further relates to a method for producing a carbonate-bonded article by carbonation, comprising the supply of a precursor to a mould (1, 100, 101, 102) according to the invention, and to the use of a mould for obtaining such a carbonate-bonded article having a compressive strength of at least 4 MPa.

Description

Technical Field

[0001] The present invention relates to a mould for solidifying a precursor by carbonation. The present invention further relates to a method for producing a carbonate-bound article by carbonation. Background Art

[0002] The anthropogenic emission of CO2 is considered to be the cause of global climate change and potentially irreversible destructive effects on ecosystems and society. Various technologies designed to reduce the amount of greenhouse gases (such as CO2) in the atmosphere show that this is an active research area. The storage of CO2 provides the potential to prevent CO2 from entering the atmosphere (for example, by removing CO2 from industrial flue gases) or the potential way to extract CO2 already present in the atmosphere. The physical capture of CO2, such as injecting CO2 into depleted natural gas reservoirs under the seabed or in the deep sea, has not yet been proven to be a leak-proof technology option. On the other hand, chemical storage provides the potential to capture CO2 almost permanently.

[0003] Chemical sequestration can be achieved by carbonation. Carbonation is a process in which a carbonatable material is reacted with CO2 to form a carbonate precipitate. This process is also referred to as solidification by carbonation. Known carbonatable materials include alkaline earth metals (e.g., calcium and magnesium), transition metals, and post-transition metals, present as their oxides, hydroxides, or as silicate phases. The resulting carbonated products are primarily bonded by carbonates.

[0004] Typical examples of carbonated or carbonate-bound products are construction products and building products, such as concrete masonry blocks, concrete paving blocks, concrete slabs, bricks, concrete pipes, fiber cement boards and cement-bonded particle boards.

[0005] The first method of solidification by carbonation is a so-called "dry" method, in which the carbonatable material is provided as particles that are formed by compacting under pressure (typically in a mold) before solidification. The particles can contain a limited amount of water (typically up to 20% by weight based on the dry weight of the particles), which typically exists as moisture or hydrates. It is known that this limited amount of water allows the particles to be shaped more easily. The shaped particles are typically removed from the mold and then solidified by carbonation in a humid environment. The presence of water in the particles and / or the surrounding atmosphere allows the dissolution of alkali metals, transition metals and / or post-transition metals from the silicates and / or hydroxides in the particles. The dissolved alkali metals, transition metals and / or post-transition metals are reacted with the carbonate ions formed by the dissolution of CO2 in water, resulting in the formation of carbonates in the solution. The carbonates hold the other components of the granular material together, i.e., glue them together, producing a product based on carbonates.

[0006] Another method comprises (one or more) carbonatable materials (for example (one or more) carbonatable materials described above) is mixed with aqueous source (such as water) to form flowable mixture.Then mixture (also referred to as precursor, mixed precursor or suspension) is provided in mould for shaping mixture.Mold defines the shape or geometry of the carbonating article obtained.Can be supplied to mould by pouring mixture, optionally with making mixture or precursor vibration combination to remove any bubble of trapped air.Then make the mixture of shaping typically be exposed to CO in a heated environment or with CO contact, make (one or more) carbonatable materials and CO reaction, cause formation carbonate bonding article.

[0007] GB 392,340 discloses a method for producing synthetic building materials from lime. A slurry of slaked lime is aerated by contacting it with bubbles twice its volume. The foamed slaked lime slurry is then fed into a porous mold made of perforated or woven metal. The mold is then placed in a heated chamber or tunnel through which CO2 is circulated. The slaked lime is carbonated, and any water formed is expelled as water vapor due to the elevated temperature in the chamber or tunnel. A low-density carbonated material is obtained.

[0008] WO 2012 / 079173 discloses a concrete product obtained by carbonation in a mold. The mold comprises a core assembly having a plurality of perforations extending across at least one core of the core assembly. During carbonation, CO2 is injected through the perforations at elevated pressure (e.g., 350 kPa above atmospheric pressure) for a period of about 60 seconds or less.

[0009] The shortcoming of aforementioned mould comprises that mixture (or precursor or suspension) tends to fill the perforation of mould or mould core when being supplied in mould.When carbonating, the precursor material in perforation is also carbonating, and makes thus the removal (so-called demoulding) complication of carbonate-based (or carbonating) goods from mould.Another shortcoming is that the mixture of lower viscosity (or higher liquid / solid ratio) tends to leak from mould by perforation, for example, drips out.In addition, mixture and therefore carbonating goods tend to meet the perforation texture of mould or mould core, and this is normally undesirable.The other shortcoming of aforementioned method is the pressure that typically needs raising to be injected into precursor with CO2.

[0010] JP 2002127122 discloses a kind of mould for making concrete carbonation, and this mould has core member and air-permeable and water-permeable sheet material, and this sheet material is provided so that cover whole core member.The core member can be a honeycomb structure, and can be made of plastics, aluminium, iron, glass fibre or carbon fibre.In order to enhance strippability, the particle of foamed resin can be attached to the surface on the side contacting with moulded article of air-permeable and water-permeable sheet material.Mold allows the easier removal (strippability) of carbonation product and has better reusability.

[0011] CN 217226056 U discloses a mold for manufacturing exterior wall decorative panels. The mold includes ventilation holes on its sides and bottom. A mesh is arranged on the mold to prevent concrete from flowing out through the holes.

[0012] US2020 / 0055778 discloses methods for producing shaped articles comprising synthetic marble-like materials. These methods include providing a slurry mixture in a mold or on a substrate, and then exposing the mixture to CO2. The mold is porous, allowing CO2 to be supplied to the slurry to be carbonated through its pores. The mold can be made of a variety of suitable materials, including metal, plastic, rubber, and ceramic.

[0013] A disadvantage of the aforementioned molds is that lower viscosity (or higher liquid / solid ratio) mixtures tend to leak, eg drip, from the mold through the perforations. Summary of the Invention

[0014] The present invention aims to overcome one or more of the above shortcomings. The object of the present invention is to provide a mold for solidifying a precursor by carbonation, wherein the precursor can have a liquid-to-solid ratio varying between a low value and a high value, including an aqueous suspension. Another object is to provide a mold that allows the precursor to be solidified in a uniform and uniform manner when present in the mold. Yet another object is to provide a mold that allows solidification at a higher rate than existing molds. Another object is to provide a mold in which CO2 can be provided to the precursor without the need for high pressure. Even further object is to provide a mold that allows the at least partially carbonated product to be easily demoulded.

[0015] It is also an object of the present invention to provide a process for producing carbonate-bound articles by carbonation from a wide range of precursors (low to high liquid-solid ratios), wherein the solidification is rapid and uniform.

[0016] The term "hydraulic binder" in the present disclosure means any material that hardens upon contact with water (eg by addition of water).

[0017] The term "binder" as used in this disclosure may refer to one or a combination of one or more carbonatable materials and one or more hydraulic binders (as defined above). The binder may also contain one or more inert materials, although the portion of inert materials will generally be kept at a low level. The binder is advantageously a granular or particulate material, advantageously having a particle size of less than 100 μm.

[0018] According to a first aspect of the present invention there is provided a mould for curing a precursor by carbonation as described in the accompanying claims.

[0019] The mold comprises a reaction compartment, such as a reaction volume, configured to receive a precursor and cure the precursor.

[0020] The reaction compartment comprises a liquid-impermeable wall. The term "liquid-impermeable" is used in this disclosure to prevent the passage or penetration of liquids (including both low-viscosity and high-viscosity substances, such as water). Therefore, in this disclosure, the term "liquid-impermeable wall" refers to a wall, i.e., a structure or barrier, that effectively prevents liquid from flowing or leaking through the wall in any direction.

[0021] The liquid-impermeable wall is permeable to CO2, allowing CO2 to be supplied to the precursor through the wall while preventing liquid water from escaping through the wall. In other words, and advantageously, at least a portion of the area of the wall exposed to the reaction compartment is permeable to CO2. Advantageously, at least a portion of the area of the wall exposed to the reaction compartment has a CO2 permeability of at least 0.001 GPU at 70°C and 20 bar, preferably at least 0.01 GPU at 70°C and 20 bar, more preferably at least 0.1 GPU at 70°C and 20 bar, such as at least 1 GPU at 70°C and 20 bar, or at least 10 GPU at 70°C and 20 bar.

[0022] Advantageously, at least a portion of the area of the wall exposed to the reaction compartment has a CO2 permeability between 0.001 GPU and 1000 GPU at 70°C and 20 bar, preferably between 0.01 GPU and 500 GPU at 70°C and 20 bar, more preferably between 0.01 GPU and 250 GPU at 70°C and 20 bar, or between 1 GPU and 100 GPU at 70°C and 20 bar.

[0023] Advantageously, the liquid-impermeable wall is permeable to water vapor.Thus, and advantageously, the liquid-impermeable wall can be considered to be substantially gas-permeable.

[0024] Advantageously, at least 1%, preferably at least 2%, more preferably at least 5%, such as at least 10% of the total wall area of the reaction compartment is made of a material permeable to CO2.

[0025] Advantageously, between 1% and 95%, preferably between 2% and 90%, such as between 5% and 80%, or between 10% and 75% of the total wall area of the reaction compartment is made of material permeable to CO2.

[0026] Advantageously, the material permeable to CO2 has a CO2 permeability of at least 0.001 GPU at 70°C and 20 bar, preferably at least 0.01 GPU at 70°C and 20 bar, more preferably at least 0.1 GPU at 70°C and 20 bar, such as at least 1 GPU at 70°C and 20 bar, or at least 5 GPU at 70°C and 20 bar.

[0027] Advantageously, the material permeable to CO2 has a CO2 permeability between 0.001 GPU and 1000 GPU at 70°C and 20 bar, preferably between 0.01 GPU and 500 GPU at 70°C and 20 bar, more preferably between 0.01 GPU and 250 GPU at 70°C and 20 bar, or between 0.01 GPU and 100 GPU at 70°C and 20 bar.

[0028] Advantageously, a portion of the area of the wall exposed to the reaction compartment (which is permeable to CO2, such as a material permeable to CO2) comprises or consists essentially of one or more of the following: silicone rubber (also known as polydimethylsiloxane, or PDMS), dimethyl silicone rubber, EPDM rubber, polyvinyl alcohol, polyethylene oxide (PEO), intrinsically microporous polymers (PIMs), thermally rearranged polymers and ethyl cellulose.

[0029] Advantageously, the liquid-impermeable wall comprises a reinforcement layer.Advantageously, the reinforcement layer comprises at least one through-opening, such as a hole or a perforation.

[0030] Advantageously, the liquid-impermeable wall further comprises a second layer made of a second material that is liquid-impermeable and CO2-permeable. In other words, the second layer is made of a second liquid-impermeable material having a CO2 permeability as defined above, i.e. at least 0.001 GPU at 70°C and 20 bar.

[0031] The second layer advantageously covers the at least one through-opening. In other words, the at least one through-opening is advantageously closed by the second layer.

[0032] In the present disclosure, "enclosed" means that the second layer is arranged such that the entire surface area of the through-opening(s) in the reinforcing layer is blocked or sealed by the second layer, thereby ensuring that the wall is liquid-impermeable. Thus, liquids and also precursors cannot pass through the wall, while at the same time, gases, in particular CO2 and water vapor, can pass through the liquid-impermeable wall via the at least one through-opening and the gas-permeable second layer covering the through-opening(s).

[0033] Advantageously, the reinforcement layer comprises an open area between 1% and 95%, preferably between 2% and 90%, such as between 5% and 80%, or between 10% and 75%. In the present disclosure, "open area" means the ratio of the area of (one or more) through-openings to the total area of the reinforcement layer.

[0034] Advantageously, the reinforcing layer and the second layer are stacked. For example, the second layer can be arranged on one or both sides of the reinforcing layer. The liquid-impermeable wall can comprise two or more reinforcing layers and / or two or more second layers, which are advantageously stacked, for example, by alternating reinforcing layers and second layers.

[0035] Alternatively and also advantageously, the reinforcement layer is embedded in the second layer.

[0036] Advantageously, the reinforcement layer comprises or consists essentially of a polymer, steel, wood, and / or a wood-based material.

[0037] Advantageously, the polymer is selected from the group consisting of polyurethane, polyethylene, polypropylene, polystyrene and polycarbonate. Examples of polyethylene are high density polyethylene and ultra high density polyethylene.

[0038] Advantageously, the wood based material is selected from the group consisting of plywood, medium density fibreboard, high density fibreboard and optionally corrugated cardboard.Advantageously, the reinforcement layer comprises or consists essentially of wood.

[0039] Advantageously, the second material comprises or consists essentially of one or more of: silicone rubber (also known as polydimethylsiloxane, or PDMS), dimethyl silicone rubber, EPDM rubber, polyvinyl alcohol, polyethylene oxide (PEO), inherently microporous polymers (PIMs), thermally rearranged polymers, and ethyl cellulose.

[0040] As will be appreciated, the reinforcing layer provides form stability to the liquid-impermeable wall and, by extension, to the reaction compartment and mold. This allows for the production of carbonate-based articles having predefined geometries or shapes. In other words, the reinforcing layer ensures that the wall is sufficiently robust to ensure the volumetric stability of the precursor contained therein during use. For example, the wall is able to withstand forces and pressures exerted thereon by the precursor during use.

[0041] Advantageously, the reaction compartment comprises a bottom wall and one or more circumferential side walls. The one or more circumferential side walls advantageously, preferably completely surround the bottom wall. Advantageously, a liquid-impermeable wall forms at least one of the one or more circumferential side walls. Preferably, the liquid-impermeable wall also forms the bottom wall. Preferably, the top of the mold is open. Such an open top advantageously allows the precursor to be easily supplied to the mold, and in particular to the reaction compartment. Alternatively, the mold may further comprise a covering, such as a lid, for closing the top of the mold, particularly after the precursor is supplied to the mold.

[0042] According to a second aspect of the present invention, there is provided a mold assembly as described in the accompanying claims. Advantageously, the mold assembly comprises a mold according to the first aspect of the present invention. Advantageously, the mold assembly further comprises a supply system configured to supply a gas containing CO2 to the reaction compartment. Advantageously, the mold assembly is configured to supply at least a portion of the gas containing CO2 to the reaction compartment through the liquid-impermeable wall.

[0043] According to a third aspect of the present invention there is provided a method of producing a carbonate-bound article by carbonation as described in the accompanying claims.

[0044] The method comprises preparing a precursor. The precursor comprises a carbonatable compound. The precursor may be a precursor known in the art. Advantageously, the precursor comprises water, i.e., is a suspension or slurry. The precursor may further comprise a hydraulic binder.

[0045] The method further comprises supplying the precursor to a mould, thereby shaping the precursor.The mould is according to the first aspect of the invention. Advantageously, the precursor is supplied to a reaction compartment of the mould.

[0046] The method further comprises exposing the mold containing the shaped precursor to an atmosphere containing at least 0.5% by volume of CO2 at a temperature between 5°C and 120°C and at a pressure between 0.01 bar and 50 bar, wherein the pressure is expressed as an overpressure relative to atmospheric pressure.

[0047] Advantageously, the relative humidity is between 5% and 100%, such as between 10% and 100%.

[0048] Advantageously, the atmosphere comprises at least 1% by volume of CO2, such as at least 5% by volume of CO2, preferably at least 10% by volume of CO2, more preferably at least 20% by volume of CO2.

[0049] Advantageously, the pressure within the atmosphere is between 0.1 and 25 bar, such as between 0.2 and 10 bar, preferably between 0.5 and 5 bar, for example between 1 and 3 bar.

[0050] Advantageously, the temperature is between 10 and 110°C, such as between 15 and 100°C, preferably between 20 and 60°C.

[0051] When the mold containing the shaped precursor is exposed to the atmosphere, CO2 is contacted with the precursor, in particular with at least a portion of the carbonatable compound. Advantageously, CO2 contacts the precursor through a portion of the wall surface that is permeable to CO2.

[0052] Advantageously, the mould comprising the shaped precursor is exposed to atmosphere for enough duration so that at least a portion of the carbonatable compound and CO react. Carbonatable compound (or at least a portion thereof) and CO react therebetween to form a carbonate. As known in the art, these carbonates serve as a binder material in the goods obtained. In other words, the goods obtained are carbonate bonded goods. Advantageously, carbonate bonded goods mean that wherein carbonate contributes at least 15%, such as at least 20% or at least 25% to the ultimate compressive strength of goods.

[0053] Alternatively, the mold containing the shaped precursor may be exposed to the atmosphere as described above once or more times, ie, two or more times in total.

[0054] Advantageously, the carbonate-bonded product obtained has a compressive strength of at least 4 MPa, preferably at least 20 MPa, such as at least 30 MPa. Advantageously, the carbonate-bonded product obtained has a compressive strength between 4 MPa and 150 MPa, preferably between 20 MPa and 120 MPa, or between 30 MPa and 90 MPa.

[0055] The present invention further comprises the use of the mould according to the first aspect for obtaining a carbonate-bonded product having a compressive strength of at least 4 MPa, preferably at least 20 MPa, such as at least 30 MPa. Advantageously, the present invention comprises the use of the mould according to the first aspect for obtaining a carbonate-bonded product having a compressive strength of between 4 MPa and 150 MPa, preferably between 20 MPa and 120 MPa, or between 30 MPa and 90 MPa. The carbonate-bonded product may be, but is not limited to, a building product or a product used in construction.

[0056] Advantages of the mold of the present disclosure include, but are not limited to, the possibility of receiving a wide variety of precursors (i.e., two precursors with a low water to binder ratio and a high water to binder ratio). The mold provides sufficient form stability, i.e., volume stability, to shape the precursors and obtain a carbonate-bound article with a predefined shape or geometry.

[0057] An additional advantage of the mold of the present invention is that the CO can contact the carbonatable compound in the precursor from different sides or angles, allowing for more uniform and faster carbonation without requiring high pressure to inject the CO into the precursor. Furthermore, any excess water released as water vapor during the carbonation reaction can be easily vented or removed from the reaction compartment of the mold containing the precursor.

[0058] Yet further advantages include easy demoulding of carbonate-bonded articles. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Aspects of the present invention will now be described in more detail with reference to the accompanying drawings, in which like reference numerals indicate like features, and in which:

[0060] Figure 1 A mould according to the invention is schematically represented.

[0061] Figure 2 Another mould according to the invention is schematically shown.

[0062] Figure 3 A further mould according to the invention is schematically represented.

[0063] Figure 4 Yet another mould according to the invention is schematically represented.

[0064] Figure 5 denotes a liquid-impermeable wall according to the invention.

[0065] Figure 6 shows another liquid-impermeable wall according to the present invention.

[0066] Figure 7 represents a further liquid-impermeable wall according to the invention.

[0067] Figure 8 represents yet another liquid-impermeable wall according to the present invention.

[0068] Figure 9 represents yet another liquid-impermeable wall according to the present invention.

[0069] Figure 10 It shows a carbonate-bonded product obtained using the mold of the present invention.

[0070] Figure 11 Denotes a carbonate-bonded product obtained with a mould whose walls are covered with an airtight tape.

[0071] Figure 12 Shown are carbonate-bonded articles obtained with the moulds of the invention having different thicknesses.

[0072] Figure 13 Denotes carbonate-bonded products obtained using polystyrene moulds. DETAILED DESCRIPTION

[0073] Figure 1 A mold 1 is shown comprising a reaction compartment 2. The reaction compartment 2 comprises a liquid-impermeable wall 3. The reaction compartment 2 has an open side, here the top. The open side advantageously facilitates the supply of precursors to the reaction compartment 2. When the reaction compartment 2 has an open side, a liquid-impermeable covering, such as a lid (not shown), may optionally be provided to close or seal the reaction compartment 2. The liquid-impermeable covering is gas-permeable. The gas-permeable covering allows CO to be transferred through the covering toward the precursor during use of the mold, and any excess water vapor formed during use of the mold is released from the reaction compartment to the surrounding atmosphere.

[0074] At least a portion of the area of the wall exposed to the reaction compartment is gas permeable, and in particular permeable to CO 2. Advantageously, the liquid-impermeable and gas-permeable portion has a CO 2 permeability of at least 0.001 GPU at 70° C. and 20 bar as defined above.

[0075] Figure 2 Another mold 100 of the present invention is shown. Mold 100 comprises a reaction compartment 2 having a star-shaped cross section and having a liquid-impermeable wall 3. Reaction compartment 2 comprises a bottom wall 10, or bottom surface. Reaction compartment 2 further comprises a circumferential side wall 11. Circumferential side wall 11 completely surrounds bottom wall 10.

[0076] The bottom wall 10 and the circumferential side wall 11 are liquid-impermeable. At least a portion of the side wall 11 and / or the bottom wall 10 is gas-permeable, in particular CO2-permeable and preferably also water vapor-permeable, wherein gas-permeable and CO2-permeable are as described above.

[0077] Figure 3 Another mold 101 of the present invention is shown. Figure 1 and 2 Compared to the reaction compartments 2 of molds 1 and 100, mold 101 has a more complex shaped reaction compartment 2. Mold 101 includes liquid-impermeable walls 3 defining reaction compartment 2. A portion of the area of liquid-impermeable walls 3 exposed to reaction compartment 2 has a CO2 permeability of at least 0.001 GPU at 70°C and 20 bar.

[0078] Figure 4 A still further mould 102 is shown comprising a liquid-impermeable wall 3 and a reaction compartment 2. The wall 3 is curved.

[0079] Figure 5The liquid impermeable wall 31 is schematically shown. The liquid impermeable wall 31 can be used to Figures 1 to 4 in molds 1, 100, 101 and 102.

[0080] The wall 31 comprises a reinforcement layer 4. The reinforcement layer 4 comprises a plurality of through openings. The cross-sectional shape and size (surface area) of the through openings 6 can vary. For example, the cross section can be circular, rectangular, or star-shaped. The through openings 6 can be positioned at a constant distance from each other (e.g., Figure 5 ), or may be randomly distributed (not shown). Advantageously, the open area of the reinforcement layer is advantageously between 1% and 90%, such as between 5% and 80%.

[0081] The wall 31 further comprises a second layer 5 made of a second material that is liquid-impermeable and CO2-permeable, wherein the permeability to CO2 is as described above, ie the second material has a CO2 permeability of at least 0.001 GPU at 70° C. and 20 bar.

[0082] Advantageously, the second material is as described above. Preferred examples of silicone rubber include, but are not limited to, dimethyl silicone rubber, phenyl silicone rubber, and fluorosilicone rubber. The second material may further comprise and consist essentially of polyethylene, particularly low-density polyethylene, polypropylene, polypropylene oxide (PPO), PEO-PPO, polyurethane, thermoplastic elastomer-PIM (TPE-PIM), PIM-polyimide (PIM-PI), or a combination of two or more thereof.

[0083] The second layer 5 covers all (one or more) through-openings 6. The inventors surprisingly found that CO2 can pass through the wall 31 at a sufficient rate at a pressure of about atmospheric pressure or at an overpressure of up to 5 bar, such as 3 bar, and therefore no elevated pressure is required. In other words, CO2 can pass through the wall 31 at a sufficient rate without a substantial pressure difference between the outside and the inside of the reaction compartment.

[0084] The reinforcing layer 4 and the second layer 5 are stacked. The second layer 5 is arranged on the side of the reinforcing layer 4 facing the interior of the reaction compartment (not shown), that is, the side that comes into contact with the precursor during use. This allows for reducing or even preventing the deposition of precursor material within at least a portion of the through-opening 6. The inventors have found that by doing so, when the mold is used, the resulting article can be demoulded more easily. This is primarily because the precursor material is prevented from adhering, attaching, or anchoring to the reinforcing layer 4 during use of the mold.

[0085] Advantageously, the second material 5 has a thickness between 0.25 mm and 25 mm, such as between 0.5 mm and 20 mm, or between 1 mm and 15 mm. It will be understood that the thickness depends inter alia on the composition of the second material 5.

[0086] Figure 6 Schematically shown is another liquid-impermeable wall 32. The liquid-impermeable wall 32 comprises a reinforcement layer 40 and a second layer 50 arranged on one side of the reinforcement layer, the reinforcement layer comprising a plurality of through openings 60. The second layer 50 is as described above.

[0087] The liquid impermeable wall 32 is Figure 5 The difference of the liquid-impermeable wall 31 of FIG. 5 is that the reinforcement layer 40 is a net or grid. For example, the reinforcement layer 40 can be made of steel, such as stainless steel.

[0088] The second layer 50 is attached to the mesh (reinforcement layer 40) and covers the through openings 60. The attachment may be achieved by gluing or by other attachment methods known in the art.

[0089] Figure 7 Another liquid-impermeable wall 33 is schematically shown. The liquid-impermeable wall 33 comprises a reinforcement layer 41 and a plurality of second layers, the reinforcement layer comprising a plurality of through openings 61. The wall 33 and Figure 5 The wall 31 of the embodiment of the present invention differs in that the CO2 permeable second material of the plurality of second layers 51 is only arranged in the through-openings 61. Therefore, the second material at least partially fills the through-openings 61. The second material of the plurality of second layers 51 may be the same for each second layer 51 or may be different.

[0090] According to the present disclosure, "at least partially filled" means that the through-opening(s) are filled with the second material such that the surface area of the through-opening is completely covered with the second material and the volume of the second material in the through-opening is at least 1% of the total volume of the through-opening. Advantageously, the volume of the second material in the through-opening is at least 2%, preferably at least 5%, for example at least 10%, or at least 20% of the total volume of the through-opening.

[0091] Figure 8 Schematically shown is yet another liquid-impermeable wall 34. The liquid-impermeable wall 34 comprises a reinforcement layer 42 comprising a plurality of through-openings 62, such as perforations.

[0092] Wall 34 further comprises a plurality of second layers 52, 152 made of a second material that is liquid-impermeable and CO2-permeable. The plurality of second layers 52 at least partially fill perforations 62. The second materials of second layers 52, 152 can be the same or different. Second materials 52, 152 can be provided using methods known in the art.

[0093] Figure 9Schematically shown is a liquid-impermeable wall 35. The wall 35 comprises a reinforcing layer 8 embedded in a second layer 7 made of a CO2 permeable material. In other words, the reinforcing layer 8 is arranged so that it is surrounded by the second layer 7 in the liquid-impermeable wall 35.

[0094] The reinforcement layer 8 may comprise or may be a mesh or grid (e.g. Figure 9 ). Alternatively, or in addition, the reinforcement layer 8 may include, but is not limited to, threads, cords, or a textile structure, such as a woven structure, a knitted fabric, or a non-woven structure (not shown).

[0095] The reinforcing compound 8 may comprise or essentially consist of known reinforcing materials such as steel (eg stainless steel), glass, carbon-based compounds (eg carbon fibers), polymers (eg cellulose-based fibers such as flax or hemp), or ceramics.

[0096] Alternatively, or in addition to the reinforcement layer, the wall may comprise a reinforcement compound provided as fibres, particles or granulates dispersed within a CO2 permeable region of the wall, such as the second layer (not shown).

[0097] The present invention further relates to a method for producing a carbonate-bound article by carbonation as described above. Optionally, after supplying the precursor to the mold and before or during the step of exposing the mold containing the shaped precursor to CO2, the shaped precursor is vibrated in the mold. Vibrating the shaped precursor can help remove air bubbles trapped in the precursor.

[0098] Precursor can be any precursor that comprises carbonatable compound.Carbonatable compound can be any carbonatable compound known in the art.Especially, carbonatable compound can comprise the source of alkali metal, alkaline earth metal or transition metal, for example its silicate, oxide, hydroxide or sulfate.

[0099] Carbonatable compounds can be obtained from naturally occurring rocks and minerals, and / or from residues (eg, by-products or waste products) from industrial processes such as steel or cement manufacturing.

[0100] Advantageously, the carbonatable compound is provided as a granular material (i.e., a material consisting of particles). The particles can have different sizes. The particles can have a wide or narrow particle size distribution. Advantageously, at least 50% by volume of the granular carbonatable material has a particle size less than 2mm, preferably less than 1mm, more preferably less than 0.5mm. Advantageously, at least 50% by volume of the granular material has a particle size greater than 15 μm, more preferably greater than 20 μm, such as greater than 25 μm. The particle size can be determined by means of techniques and devices known in the art, for example, by means of laser diffraction, particularly for particles with a particle size lower than 1mm or 0.5mm.

[0101] Optionally, the precursor may comprise further additives, such as hydraulic binders, plasticizers (eg so called superplasticizers), acids, caustic materials or salts.The optional hydraulic binder, the optional plasticizer and the further optional additives may be compounds known in the art.

[0102] Advantageously, the precursor is obtained by adding the carbonatable compound and optional additives to water, thereby obtaining the precursor.The precursor may be a suspension, a slurry or a slurry of the carbonatable compound in water.

[0103] Advantageously, the carbonate bonded article obtained has a green strength that is enough to allow the demoulding of the article. Alternatively, the article can be exposed to a CO comprising at least 0.5 volume % after demoulding through one or more additional steps of an atmosphere. Such (one or more) additional steps can be carried out (i.e., the article has enough green strengths) without the need for the article being placed in a mold. Compared with the carbonation only carried out in the mold, this type of additional step allows obtaining a higher degree of carbonation of the article, particularly in a shorter time period. It is known that a higher degree of carbonation contributes to an increase in the intensity, particularly its compressive strength, of the carbonate bonded article.

[0104] When the article undergoes a further exposure step, it may be exposed to an atmosphere comprising at least 0.5% by volume of CO 2 at a temperature between 5° C. and 120° C. and at a pressure between 0.1 bar and 50 bar.

[0105] Example

[0106] Example 1

[0107] The precursor was prepared by adding quartz sand, crushed argex, coarse aggregate and a d 50 The binder (which comprises a carbonatable material according to the definition given above) is mixed with water at a value of 0.40 and a water / solid (or liquid / solid) ratio of 0.09. The binder is an electric arc furnace (EAF) stainless steel slag comprising calcium silicate.

[0108] Three different molds are provided. All three molds have Figure 1 The geometry shown in FIG has internal dimensions of 16 cm long, 4 cm wide and 4 cm high. The thickness of the side and bottom walls is 2 cm. The top side is left open.

[0109] The first mold is made of silicone rubber. The second mold is made of silicone rubber and its outer surface is covered with aluminum tape. The third mold is made of silicone rubber and its outer surface is covered with polytetrafluoroethylene (PTFE) tape.

[0110] An equal amount of precursor is supplied to all three molds.The mold containing the shaped precursor is then placed in an atmosphere containing CO2 for at least partially carbonating the carbonatable compound.

[0111] One carbonation cycle was performed by exposing the mold containing the shaped precursor to the conditions of Table 1.

[0112] Afterwards, the carbonate-bonded articles were evaluated for strength and demolding. First, they were evaluated for sufficient strength to allow for demolding in a single piece. If the strength was deemed sufficient, the demolding of the article was evaluated by examining whether demolding was easy or difficult and how the demolded article looked.

[0113] Table 1: Process parameters of the carbonation cycle

[0114] <![CDATA[Volume % CO2]]> temperature pressure relative humidity Duration Loop 1 50% by volume 30℃ 3 bar 75％ 48h

[0115] The article obtained with the first mold has sufficient strength to allow demoulding. Demolding is easy and a smooth surface is obtained ( Figure 10 The articles obtained with the second and third molds (ie having outer sides covered with aluminum and PTFE tapes, respectively) did not show sufficient strength for demoulding in one piece ( Figure 11 For the product obtained with the third mold after demoulding).

[0116] Example 2

[0117] Four different molds were provided. All four molds were made of silicone rubber and had the dimensions and wall thicknesses shown in Table 2. The top side was left open.

[0118] Table 2: Internal mold dimensions and wall thickness

[0119] length width high thickness Mold 1 4cm 4cm 4cm 0.3cm Mold 2 4 cm 4cm 4cm 2cm Mold 3 16 cm 4cm 4cm 1cm Mold 4 16 cm 4cm 4cm 2cm

[0120] All four moulds were supplied with the precursor of Example 1. The moulds containing the shaped precursors were then placed in an atmosphere containing CO2 for at least partial carbonation of the carbonatable compound.

[0121] Carry out carbonation cycle by making the mould that comprises shaped precursor be exposed to the corresponding conditions of table 3.By changing the duration of carbonation cycle, carry out three variants of carbonation process.Variant 1 comprises 1 30 hour cycle, variant 2 comprises 1 36 hour cycle, and variant 3 comprises 1 42 hour cycle.In other words, make one mould of every type (therefore a total of four different moulds) carbonation according to the parameter of variant 1.Make one mould of every type (therefore a total of four different moulds) carbonation according to the parameter of variant 2.And make one mould of every type (therefore a total of four different moulds) carbonation according to the parameter of variant 3.This allows to study the influence of the duration of the carbonation process of each mould.

[0122] Table 3: Process parameters of carbonation cycle

[0123] <![CDATA[Volume % CO2]]> temperature pressure relative humidity Duration Variant 1 50% by volume 30℃ 3 bar 75％ 30h Variant 2 50% by volume 30℃ 3 bar 75％ 36h Variant 3 50% by volume 30℃ 3 bar 75％ 42h

[0124] Afterwards, as explained in Example 1, each carbonate-bonded article was evaluated for strength and demoulding.

[0125] Note that for all three variations of the carbonation process, the carbonation process was carried out using mold 1 (4 cm thick with a thickness of 0.3 cm). 3 Sufficient strength and easy demoulding were achieved with Molds 2 and 4 (cubic mold) and Mold 3 (16 cm*4 cm*4 cm prismatic mold with a thickness of 1 cm), whereas with Molds 2 and 4 having a thickness of 2 cm, the products did not have sufficient strength to allow proper demoulding even after a carbonation process duration of 42 hours.

[0126] Figure 12 The articles obtained after 36 hours of cycling are shown. Article 200 obtained with mold 1 and article 201 obtained with mold 3 show no damage and have smooth sides, while article 202 obtained with mold 2 and article 203 obtained with mold 4 show significant damage and cannot be demolded in one piece.

[0127] Example 3

[0128] Three different molds are provided. All three molds have Figure 1 The geometry shown in FIG has internal dimensions of 16 cm long, 4 cm wide and 4 cm high. The thickness of the side and bottom walls is 1 cm. The top side is left open.

[0129] The first mold was a reference mold and was made of steel. The second mold was a reference mold and was made of polystyrene. The third mold was mold 3 of Example 2.

[0130] All three moulds were supplied with an equal amount of the precursor of Example 1. The mould containing the shaped precursor was then placed in an atmosphere containing CO2 for at least partial carbonation of the carbonatable compound.

[0131] Five carbonation cycles were performed by exposing the mold containing the shaped precursor to the corresponding conditions of Table 4.

[0132] After each cycle, the carbonate bonded articles were evaluated for strength and demoulding as explained in Example 1.

[0133] Table 4: Process parameters of the carbonation cycle

[0134]

[0135]

[0136] The article obtained in the steel mold did not have sufficient strength to allow demolding after cycles 1, 2, and 3. Although the article did show sufficient strength after cycle 4, demolding was difficult and required the use of a hammer. The demolded article showed severe signs of damage.

[0137] The article obtained in the polystyrene mould showed cracks and rough sides after demoulding. The mould itself had cracks in the bottom wall and the side walls were clearly deformed, as seen from the Figure 13 Visible in.

[0138] The article obtained in the silicone rubber mold of the present invention allows demoulding already after cycle 2. Furthermore, demoulding is easy and the article obtained has smooth side surfaces.

[0139] Example 4

[0140] Two precursors were tested. Precursor 1 contained stainless steel slag as the carbonatable material, various fine and coarse aggregates, and approximately 8% water by weight, based on the total weight of the precursor. Precursor 2 contained BOF slag as the carbonatable material, various fine and coarse aggregates, and approximately 8% water by weight, based on the total weight of the precursor.

[0141] Each precursor was added to a Figure 1 The geometry shown in the figure is molded with internal dimensions of 4 cm long, 4 cm wide and 4 cm high. The top side is left open. The wall thickness is 3 mm and the wall is made of silicone rubber.

[0142] The mold containing the precursor was exposed to an atmosphere containing 50% by volume of CO 2 at 40° C., 3 bar and at a relative humidity of 10%.

[0143] Determine until the duration of complete carbonation. Precursor 1 was completely carbonated after 9 hours, and precursor 2 was completely carbonated after 48 hours. This shows, depending on the composition of the precursor, it is possible to obtain complete carbonation after the short duration that is less than 12 hours.

[0144] Example 5

[0145] The precursor was prepared by adding quartz sand (Rhine sand 0-3m), quartzite aggregate (2-5mm) and a 12μm d 50 A binder (which comprises a carbonatable material according to the definition given above) of 500 mg / L is mixed with water such that the water / binder ratio is 0.356. A superplasticizer is further added.

[0146] A mold made of silicone rubber and having internal dimensions of 40 mm x 40 mm x 40 mm is provided. The precursor is supplied to the mold. The mold containing the shaped precursor is then placed in an atmosphere containing CO2 for at least partially carbonating the carbonatable compound.

[0147] Carbonation was performed by exposing the mold containing the shaped precursor to the conditions of Table 5. Three different carbonation durations were tested: 12 hours, 24 hours, and 48 hours.

[0148] The carbonate-bonded products (i.e., one product / carbonation duration) were then evaluated for ultrasonic pulse velocity ("UPV" in Table 6), compressive strength ("CS" in Table 6), and total carbon content ("TC" in Table 6). Compressive strength was tested according to test standard EN 196-1, and total carbon content was measured using an Analytikjena multi EA4000 device.

[0149] Table 5: Carbonation process parameters

[0150] <![CDATA[Volume % CO2]]> temperature pressure relative humidity Carbonation 35% to 40% by volume 40℃ 3 bar gauge pressure 85％-90％

[0151] Table 6: Ultrasonic pulse velocity, compressive strength and carbon content as a function of carbonation duration

[0152] Duration UPV CS (MPa) TC (%) 12h 3490±30 16.7±1.4 0.61 24h 3760±20 31.9±0.5 0.88 48h 3920±10 34.5±1.1 0.98

[0153] It is clear from Table 6 that all parameters typically used to evaluate the quality of concrete (i.e., ultrasonic pulse velocity, compressive strength, and carbon content) increase with increasing carbonation duration. The increase from 12 hours of carbonation to 24 hours of carbonation is more pronounced than the increase from further carbonation for an additional 24 hours (48 hours versus 24 hours).

Claims

1. A mould (1) for solidifying a precursor by carbonation, the mould comprising a reaction compartment (2) configured to receive the precursor and solidify the precursor, wherein the reaction compartment (2) comprises liquid-impermeable walls (3, 30, 31, 32, 33, 34, 35), characterised in that The liquid-impermeable wall is permeable to CO2, allowing CO2 to be supplied to the precursor through the wall (3, 30, 31, 32, 33, 34, 35) while preventing liquid water from escaping through the wall (3, 30, 31, 32, 33, 34, 35).

2. The mold (1) for solidifying a precursor by carbonation according to claim 1, wherein At least a portion of the area of the wall exposed to the reaction compartment has a CO2 permeability of at least 0.001 GPU at 70°C and 20 bar, preferably between 0.01 GPU and 500 GPU at 70°C and 20 bar, preferably wherein at least 1%, preferably at least 5%, of the total wall area of the reaction compartment is made of a material having a CO2 permeability of at least 0.001 GPU at 70°C and 20 bar, preferably between 0.01 GPU and 500 GPU at 70°C and 20 bar.

3. A mould (1) for solidifying a precursor by carbonation according to any one of the preceding claims, wherein The liquid-impermeable wall is permeable to water vapor.

4. A mould (1) for solidifying a precursor by carbonation according to any one of the preceding claims, wherein Between 5% and 80% of the total wall area of the reaction compartment is made of material permeable to CO2.

5. A mould (1) for solidifying a precursor by carbonation according to any one of the preceding claims, wherein The liquid-impermeable wall (3, 31, 32, 33, 34) comprises a reinforcing layer (4, 40, 41, 42) comprising at least one through-opening (6, 60, 61, 62), wherein the liquid-impermeable wall comprises a second layer (5, 50, 51, 52) made of a second material that is liquid-impermeable and CO2-permeable, wherein the second layer (5, 50, 51, 52) covers the through-opening (6, 60, 61, 62), preferably wherein the reinforcing layer (4, 40, 41, 42) comprises an open area between 5% and 80%.

6. The mold (1) according to claim 5, wherein The reinforcement layer and the second layer are stacked, or wherein the reinforcement layer is embedded in the second layer.

7. A mould (1) for solidifying a precursor by carbonation according to any one of claims 5 to 6, wherein The reinforcement layer (4, 40, 41, 42) comprises a polymer selected from the group consisting of polyurethane, polyethylene, polypropylene, polystyrene and polycarbonate, and / or comprises steel, wood and / or a wood-based material selected from the group consisting of plywood, medium density fiberboard, high density fiberboard and optionally corrugated cardboard, preferably wood.

8. A mould (1) for solidifying a precursor by carbonation according to any one of claims 5 to 7, wherein The second material comprises or consists of one or a combination of silicone rubber, dimethyl silicone rubber, ethylene propylene diene monomer rubber, polyvinyl alcohol, polyethylene oxide, an intrinsic microporous polymer, a thermally rearranged polymer, and ethyl cellulose.

9. A mould (1) for solidifying a precursor by carbonation according to any one of the preceding claims, wherein At least a portion of the liquid-impermeable wall (3) comprises one or more of silicone rubber, dimethyl silicone rubber, EPDM rubber, polyvinyl alcohol, polyethylene oxide, inherently microporous polymers, thermally rearranged polymers and ethyl cellulose.

10. Mould (1) for solidifying a precursor by carbonation according to any one of the preceding claims, wherein The reaction compartment (2) comprises a bottom wall (10) and one or more circumferential side walls (11) completely surrounding the bottom wall (10), wherein the liquid-impermeable wall (3, 31, 32, 33, 34, 35) forms at least one of the one or more circumferential side walls (11) and preferably forms the bottom wall (10), preferably wherein the top of the mold is open.

11. A mould assembly comprising a mould (1) according to any one of the preceding claims, and a supply system configured to supply a gas containing CO2 to the reaction compartment (2), wherein the mould assembly is configured to supply at least a portion of the gas containing CO2 to the reaction compartment (2) through the liquid-impermeable wall (3).

12. A method for producing a carbonate-bound product by carbonation, comprising: - preparing a precursor comprising a carbonatable compound, - supplying the precursor to a mold (1) so as to shape the precursor, - exposing the mould (1) containing the shaped precursor to an atmosphere comprising at least 0.5% by volume of CO2 at a temperature between 5°C and 120°C and at a pressure between 0.01 bar and 50 bar for a sufficient duration to react at least a portion of the carbonatable compound with CO2, thereby obtaining a carbonate-bound article, wherein the pressure is expressed as an overpressure relative to atmospheric pressure, Characterized in that the mold (1) is a mold according to any of the preceding claims.

13. The method according to claim 11, wherein The atmosphere comprises at least 10% by volume of CO2.

14. The method according to claim 11 or claim 12, wherein: This pressure is between 0.5 and 5 bar.

15. Use of the mould according to any one of claims 1 to 10 for obtaining a carbonate-bound article having a compressive strength of at least 4 MPa.

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