EA043300B1 - MULTI-STAGE HARDENING OF FUTURE PRODUCT BLANKS - Google Patents

Description

This application claims priority and benefit from United States Provisional Application No. 62/723,397, filed Aug. 27, 2018, the entire contents of which are incorporated herein.

Technical field

Disclosed herein are methods for curing articles such as preforms, associated devices and systems.

State of the art

In the present description, when a document, act or subject of knowledge is mentioned or discussed, this reference or discussion is not an admission that the document, act or subject of knowledge, or any combination thereof, was at the date of priority in the public domain, known to specialists in this field of technology, part of the general knowledge or otherwise constitute prior art under applicable law; or known to be relevant to an attempt to solve any problem related to an invention application. Hardening of raw or partially cured product blanks can be associated with a number of different technical problems, especially when such processes are carried out on a large scale. Issues such as efficiency, non-static processing conditions, consistency and reproducibility may arise. The present invention addresses these and other problems.

One example of a raw product or product blank that undergoes a curing process is concrete or cement. Concrete is especially ubiquitous. Our homes are most likely built with it, our infrastructure is built with it, as are most of our jobs. Conventional concrete is produced by mixing water and aggregates such as sand and gravel with Portland cement, with a material obtained by burning a mixture of crushed limestone and clay or materials of similar composition in a rotary kiln at a sintering temperature of about 1450°C. The production of Portland cement is not only an energy intensive process, but also a process that releases a significant amount of greenhouse gas (CO ₂ ). The cement industry accounts for approximately 5% of global anthropogenic CO2 emissions.

More than 60% of this CO2 comes from the chemical decomposition or calcination of limestone. The traditional production and use of concrete is not optimal in terms of both economics and environmental impact. These traditional concrete production technologies involve high energy consumption and carbon dioxide emissions, resulting in adverse greenhouse gas emissions into the atmosphere.

This led to the development of non-hydraulic cement formulations. Non-hydraulic cement refers to a cement that does not cure by reacting with water in a chemical reaction, but rather primarily cures by reaction with CO2 in any of its forms, such as _CO2 gas, CO2 in the form of carbon dioxide, H2CO3, or other forms. , which allow the reaction of CO2 with non-hydraulic cementitious material. The curing process is driven by carbon dioxide to form solid carbonate particles within the cured material, thus providing clear environmental benefits. For example, the non-hydraulic formulations Solidia Cement™ and Solidia Concrete™ have been described as revolutionary technologies, recognized for example as one of the top 100 new technologies by the R&D 100 awards. The production of both Solidia Cement™ and Solidia Concrete™ reduces carbon emissions by up to 70%, reduces fuel consumption by 30% and reduces water consumption by up to 80% compared to the production of traditional hydraulic concrete and/or Portland cement.

Traditional curing methods and devices for many material compositions, including conventional concrete as well as non-hydraulic concrete compositions, are made to process materials that undergo specific chemical reactions. However, in practice, the use of traditional methods and apparatus for curing blanks of future products presents certain technical problems. Problems associated with conventional curing methods and apparatus include their cost, operating and location limitations, the accuracy with which the curing process can be controlled and monitored in a consistent and repeatable manner, and the production of cured products with desired properties. Thus, there is a need for curing methods and apparatuses that provide increased versatility, accuracy, production, consistency, and cost savings.

As shown schematically in FIG. 1, 2, products 10 made of hydraulic cement or concrete composite materials, as well as non-hydraulic cement or concrete compositions, for example, concrete compositions containing calcium silicate, sand and aggregate, such as paving stones (any sizes) or blocks / slabs (again any size) can be made using the press 20 as a molding/manufacturing method. More specifically, the hollow molds 30 are supported by a support 40 such as steel (or plastic, or any other material of suitable strength) supports or flat trays. The concrete is then injected into the cavities 50 of the molds 30. Alternatively, the molds 30 are subjected to vibration to ensure optimal filling.

- 1 043300 molds 30 with concrete mix. After filling, the press 20 acts on the concrete placed in the mold 30. As a result, one or more compacts of products 10 are formed on the support 40. The compacts 10, together with the supports 40, then undergo a number of possible processing steps, such as drying, Ultimately cured in a chamber (not shown) to ensure strength. Once cured, the preforms (e.g., paving stones) are palletized by being removed from the supports 40 and stacked, typically by a machine, to form cubes of finished preforms or paving stones stacked on a transport platform, such as a pallet. Each cube may have, for example, about 540 (or more) paving stones stacked in a format of 10 paving stones on top of each other, while each layer contains 54 paving stones. It's called a paving cube. Such cubes of pavers can then be delivered to the customer. The main steps 60 associated with the above process are schematically illustrated in FIG. 3. As shown in the illustration, the components that make up the cement/concrete composition are dosed and mixed, fed into molds where they are pressed, thus forming one or more preforms. The preforms are then cured and then the fully cured preforms are stacked on a pallet for shipment to the customer. According to current large-scale manufacturing techniques, the curing process takes a very long time, for example 50 to 80 hours or even longer. During this long curing time, the paving stones remain on their supports or pressure plates. It is unprofitable to use plates for pressing for 50 to 80 hours due to the low economic and time efficiency of the entire process. The use of pressure plates throughout the curing process results in an undesirable burden on the manufacturer's pressing operations equipment and requires the manufacturer to purchase more pressure plates than in ideal situations.

In addition, paving stones are formed from non-hydraulic compositions such as Solidia Cement™ and Solidia Concrete™, mentioned above, using a gaseous reactant, i. carbon dioxide (CO ₂ ). Carbon dioxide acts as a reactant only if the materials to be carbonized cured contain a certain amount (eg 2 to 5 wt%) of water. Carbon dioxide first dissolves in water, and then turns into aqueous bicarbonate or carbonate ions, which then react with Ca ²⁺ ions in aqueous solution and passing into it from a non-hydraulic composition, forming well-bound calcium carbonate crystals/particles ( _CaCO3 ). On the other hand, such compounds cannot be cured if the pavers are completely dry. Thus, curing paving stones formed from such non-hydraulic compositions involves controlling the water content. Another disadvantage of keeping the paving stones on the press platen during the entire curing process is that the surfaces of the paving stones are in contact with the plates, this prevents or hinders the release of water from the workpiece, and also prevents or hinders direct exposure to the reagents in the curing chamber (for example, CO2 gas) .

Thus, there is a need for improved curing methods and a device that allows the pressed boards to be removed/processed and returned to the press machine as soon as possible, as well as to improve the exposure of the surfaces of the pressed blanks (for example, pavers/products) to the reagent(s) and facilitate extraction of water from them.

While certain aspects of conventional technology have been discussed to facilitate the disclosure of the invention, Applicants in no way waive these technical aspects and it is intended that the claimed invention may cover or include one or more of the conventional technical aspects described in the specification.

Disclosure of the essence of the invention

It has been found that the aforementioned disadvantages can be eliminated and certain advantages achieved by the present invention. For example, the methods, devices, and systems of the present invention provide preform curing that provides versatility, reproducibility, yield, density, and low cost.

To facilitate the description of the essence of the present invention, the disclosure contained herein, the blank products and/or cured products is a paving stone. However, it should be understood that the principles of the present invention are not limited. The principles described here apply to any number of different blanks or products, regardless of any specific references in the description of paving stones. For example, the method described herein can be used to produce concrete products, whereby the concrete product is optionally made from a binder matrix that hardens when exposed to carbon dioxide. In some embodiments of the invention, the concrete products are foam concrete products. In some embodiments, the concrete products are aerated concrete products. In some embodiments, the aerated concrete products are aerated concrete blocks and/or aerated concrete masonry element. In some embodiments, the implementation of foam concrete products are ventilated panels. In some embodiments of the invention, ventilated panels have additional structural reinforcement in the form of reinforcement. In other embodiments, the concrete products are cast concrete products such as tiles, concrete blocks, concrete slabs, wet cast slabs, and hollow core slabs.

Next, some features of the present invention will be described. It should be understood that the present invention covers any of the previously mentioned features, used alone or in combination with any other feature (or features) described in the following sections of the description or otherwise described herein, without limitation to their specific combinations. Thus, for example, the present invention is intended to cover any possible combination of the features of the claims contained in the present description, regardless of their location in the claims.

In accordance with one aspect, the present invention relates to a method for forming a plurality of cured concrete products, each of which is cured and has a compressive strength, and the method includes the introduction of a fluid mixture with the composition of the concrete components in a plurality of forms; molding the fluid mixture within a plurality of molds with one or more punches, thereby forming a plurality of preforms; partially curing the preforms to a value sufficient to provide a compressive strength that is lower than the compressive strength of the cured article, wherein a plurality of pre-curings of the preforms are carried out; collecting at least a portion of the plurality of precured preforms to form a stack having a predetermined geometric shape; and curing the stack of pre-cured blanks to a value sufficient to achieve a compressive strength of the cured article, thereby producing a stack of cured articles having a predetermined geometric shape.

The method also includes sending a stack of cured articles having a predetermined geometric shape to a customer.

A method in which the components included in the composition include one or more cement components that provide the possibility of obtaining carbonate, and one or more aggregates.

A process wherein one or more carbonate-producing cement components contain calcium silicate.

A process in which the liquid mixture contains water.

A method wherein at least one of the injection and molding steps includes one or more of pouring, vibrating, pressing, extruding, or foaming.

A method in which one or more supports is a pressure plate.

A method in which one or more plates are metal.

A process in which a plurality of blanks form paving stones, concrete blocks, tiles, hollow core slabs, wet cast slabs, concrete slabs, foam concrete products, aerated concrete products, aerated concrete masonry elements or vented panels.

A method in which the compressive strength of the precured preforms is sufficient to allow the preforms to be removed from the support while the preforms remain substantially intact.

A process wherein the compressive strength of the precured preforms is from about 2000 to about 5000 psi. inch and measured in accordance with ASTM C140 (American Society for Testing and Materials standard).

A method in which the compressive strength of the cured article is at least about 8000 psi. inch and measured in accordance with ASTM C140.

A method wherein the step of partially curing the preforms includes introducing the preforms and one or more supports into the pre-curing chamber.

A method in which the step of partially curing the preforms includes exposing the preforms and one or more supports to carbon dioxide, air, or a mixture thereof for a predetermined period of time.

A method wherein the step of partially curing the preforms includes exposing the preforms to carbon dioxide for a period of time from about 60 to about 600 minutes and a temperature from about 50 to about 120°C.

The method, in which the stage of partial curing of the blanks further includes heating at least one metal support.

A method in which the heating of at least one metal support includes heating by an electric heating system.

A method wherein the step of combining a plurality of precured blanks includes removing the precured blanks from the surface of one or more supports.

A process in which precured blanks are removed from one or more supports by an automatic palletizer or material handling and handling system.

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A method in which the given geometric shape is a cube.

A method in which the cube contains about 480 or more precured preforms.

A method wherein the step of curing the pre-cured preforms includes introducing a stack of pre-cured preforms into a curing chamber.

A method wherein the step of curing the precured preforms includes exposing the precured preforms to carbon dioxide for a period of about 10 to about 24 hours and a temperature of about 60 to about 95°C.

The method wherein the step of partially curing the preforms or the step of curing the pre-cured preforms further comprises introducing a heated gas into the pre-curing chamber or curing chamber from a location proximate the bottom of the pre-curing chamber or curing chamber.

The method, wherein the step of partially curing the preforms or the step of curing the pre-cured preforms further comprises venting heated gas from the pre-curing chamber or curing chamber from a location near the top of the pre-curing chamber or curing chamber.

The method wherein the step of curing the pre-cured preforms further includes placing the stack of pre-cured preforms on a movable platform to move the stack of pre-cured preforms from one end of the curing chamber to the opposite end.

A method wherein the blanks and their supports have a sample volume and the pre-cure chamber has an internal volume, and wherein the ratio of the internal volume of the pre-cure chamber to the volume of the sample is from about 1.05 to about 1.15.

A method in which a stack of pre-cured preforms having a predetermined geometric shape has a sample volume and a curing chamber has an internal volume, and in which the ratio of the internal volume of the curing chamber to the volume of the sample is from about 1.05 to about 1.15.

Brief description of the drawings

Fig. 1 is a schematic representation of an apparatus and method for molding one or more preforms from a liquid mixture.

Fig. 2 is a representation of one or more blanks resulting from the use of the equipment and procedures shown in FIG. 1 located on the surface of the support.

Fig. 3 is a flow chart of a typical procedure for molding cured concrete products.

Fig. 4 shows a device for curing one or more preforms.

Fig. 5 is a view of the construction of a curing chamber in accordance with some embodiments of the present invention.

Fig. 6 - an image of a stack of blanks forming a certain geometric figure, and, if necessary, a platform.

Fig. 7 is a view of the construction of a curing chamber in accordance with additional optional embodiments of the present invention.

Fig. 8 depicts the principles of the method and construction of a curing chamber in accordance with a further optional embodiment of the present invention.

Fig. 9 is a schematic representation of the principles of the method and construction of the curing chamber in accordance with yet another optional embodiment of the present invention.

Implementation of the invention

As used herein, the term preform refers to an uncured or partially cured preform or article. In some embodiments of the invention, the workpiece is a cement or concrete (composite) product.

The term carbonate production as used herein refers to material that reacts with CO ₂ via carbonization. The material is not capable of forming carbonate unless it reacts with CO ₂ via carbonization under the conditions described here. In some embodiments, the carbonate producing material may take the form of cement or concrete (composite).

The description refers to a liquid mixture, which is a mixture from which a preform can be molded or otherwise obtained having the desired geometric shape and dimensions.

Used in the description, the term essentially intact means the preservation, for the most part, the overall shape and structure of the workpiece or product. This term does not exclude the formation of relatively minor damage or crumbling of the workpiece, as long as its overall shape and structure is maintained.

The singular forms of the noun used here are also intended for the plural forms of the noun, unless the context clearly indicates otherwise. Besides,

- 4 043300 the use of the union or is intended to include unions and/or, unless the context clearly indicates otherwise.

The preposition about is an approximation term and is intended to include minor changes in literally stated amounts as understood by those skilled in the art. Such options include, for example, standard deviations associated with methods commonly used to measure constituent amounts of simple substances or components of a composite material, or other properties and characteristics. All meanings characterized by the preposition about described above are also intended to indicate the exact numerical values disclosed in the document. Moreover, all ranges include the upper and lower limits, as well as all values within these limits.

Any compositions described herein are intended to cover compositions that consist of, include, in essence, the various components identified in the present description, and also contain them, unless expressly indicated otherwise.

Some of the abbreviations used here mean the following:

ER = timely extraction (timely removal) of pressed slabs of paving stones;

PCC = blank for paving in the form of a bar;

VBUF = vertical flow from bottom to top;

CV = chamber volume (for pre-curing and for curing);

SV = sample volume (the sample may be a block or paving stone on their pressing supports, or may be blocks or stones stacked and tightly packed together to form a particular geometric shape, such as a disjoint cube or rectangular prism, for curing with or without an additional platform);

CC = continuous curing of individual paving stones entering a chamber from one side, where paving stones can be placed by means of a conveying and loading system on a moving (continuous or intermittent) conveyor, and exiting the same chamber from the other side.

Obtaining a liquid composition for the production of a workpiece.

It is contemplated that the principles of the present invention may find application to, and are not necessarily limited to, a variety of different compositions and structures. Thus, the following information should be characterizing the invention, but is not limited to examples of the composition and structure of the blanks. In some embodiments, curable preforms suitable for the curing methods, devices, and compositions of the present invention may be made from a carbonate-forming material. In accordance with additional and particular cases of the invention curable preforms suitable for curing methods, devices and compositions of the present invention can be made from calcium silicate and/or magnesium silicate and/or magnesium hydroxide.

The term calcium silicate as used herein generally refers to natural minerals or synthetic materials that are composed of one or more groups of calcium silicate phases. Examples of calcium silicate phases capable of forming carbonate include CS (wollastonite or pseudowollastonite, and sometimes with the formula CaSiO ₃ or CaO-SiC), C ₃ S ₂ (rankinite, and sometimes with the formula Ca ₃ Si2O7 or 3CaO2-SiO2), C2S ( belite, e-Ca ₂ SiO ₄ or agvit, Ca7Mg (SiO ₄ ) ₄ or bredigite, a-Ca ₂ SiO ₄ or y-Ca ₂ SiO ₄ , and sometimes with the formula: Ca ₂ SiO ₄ or 2CaO-SiO2). Amorphous phases can also form carbonate depending on their composition. Each of these materials may include one or more other metal ions and oxides (for example, aluminum, magnesium, iron, or manganese oxides) or mixtures thereof, or may include some magnesium silicate in natural or synthetic form(s) ranging from trace amounts ( 1%) to about 50% or more by weight. Examples of substances that do not form carbonates or are inert phases include gehlenite/melilite ((Ca, Na, K) ₂ [(Mg, Fe ²⁺ , Fe ³⁺ , Al, Si) ₃ O7]) and crystalline silica ( _SiO2 ). The calcium silicate phases, which provide the formation of carbonates, which are part of the calcium silicate, are not strongly hydrated when exposed to water. Due to this, composite materials obtained using calcium silicate as a binder do not create significant strength when interacting with water. The provision of strength is controlled by exposing composite materials containing calcium silicate to specific curing modes in the presence of CO2.

As used herein, the term magnesium silicate refers to natural minerals or synthetic materials that are composed of one or more groups of magnesium-containing and silicon-containing compounds, including, for example, Mg ₂ SiO ₄ (also known as forsterite) and Mg ₃ Si ₄ O ₁₀ (OH) ₂ (also known as talc) and CaMgSiO ₄ (also known as monticellite), each of which may include one or more other metal ions and oxides (eg oxides of calcium, aluminium, iron or manganese) or mixtures thereof, or may include some silicate calcium in natural or synthetic form(s) ranging from trace amounts (1%) to about

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50% by weight or more.

In exemplary embodiments of the invention, ground calcium silicate is used.

The ground calcium silicate may have an average particle size of about 1 to 100 microns (e.g., about 1 to about 80 microns, about 1 to about 60 microns, about 1 to about 50 microns, about 1 to about 40 microns, about 1 to about 30 µm, about 1 to about 20 µm, about 1 to about 10 µm, about 1 to about 5 µm, about 5 to about 90 µm, about 5 to about 80 µm, about 5 to about 70 µm, about 5 to about 60 µm, about 5 to about 50 µm, about 5 to about 40 µm, about 10 to about 80 µm, about 10 to about 70 µm, about 10 to about 60 µm, about 10 to about 50 µm, about 10 to about 40 µm, about 10 to about 30 µm, about 10 to about 20 µm, about 1 µm (magnetic powder test), 10, 15 , 20, 25, 30, 40, 50, 60, 70, 80, 90 or 100 µm.

The ground calcium silicate may have a bulk density of from about 0.5 to about 3.5 g/ml (for example, 0.5, 1.0, 1.5, 2.0, 2.5, 2.8, 3.0 or 3.5 g/ml) and a bulk density of about 1.0 to about 1.2 g/ml.

The ground calcium silicate may have a Blaine specific surface area ^from about 150 to about 700 m ² /kg ).

In exemplary uses of the calcium silicate composition, the ground calcium silicate particles have a total particle diameter of 10% greater than 1 micron in a volumetric particle size distribution. Any suitable aggregates may be used to form composite materials from the carbonate-forming composition of the present invention, such as those containing calcium oxide or silica-containing materials. Aggregates may include inert materials such as trapping, building sand, rounded fine gravel.

In some preferred embodiments of the invention, lightweight aggregates such as perlite or vermiculite can also be used as aggregates. Materials such as industrial waste (eg fly ash, slag, quartz dust) can also be used as fine fillers. Many aggregates may have any suitable average particle size and size distribution.

In some embodiments, many aggregates have an average particle size in the range of about 0.25 to about 25 mm (e.g., about 5 to about 20 mm, about 5 to about 18 mm, about 5 to about 15 mm, from about 5 to about 12 mm, about 7 to about 20 mm, about 10 to about 20 mm, about 1/8, about 1/4, about 3/8, about 1/2, about 3/4).

The composition of the composite material may also include chemical additives, such as plasticizers, retarders, accelerators, dispersants and other rheological modifiers. Some commercially available chemical additives such as Glenium™ 7500 from BASF® Chemical, HC-300 from SIKA and Acumer™ from Dow Chemical Company may also be included. In some embodiments of the invention, one or more pigments may be uniformly or substantially non-uniformly dispersed in the binder matrices, depending on the desired composite material. The pigment may be any suitable pigment including, for example, oxides of various metals (eg iron oxide black, cobalt oxide and chromium oxide). The pigment may be any color or any shade, for example selected from black, white, blue, grey, pink, green, red, yellow and brown. The pigment may be present in any suitable amount depending on the desired composite material, for example in an amount of from about 0.0 to about 10% by weight.

The main advantage of the composition used is that it provides the formation of carbonates to obtain composite materials that can be used in various fields.

It is assumed that the following reactions occur during the carbonization of calcium silicate:

CaSiOs (s) + CO2 (g) -> CaCOs (s) + SiC>2 (s) (1)

Ca ₃ Si ₂ O ₇ (s) + 3CO2 (g) 3CaCO (s) + 2SiO ₂ (s) (2)

Ca ₂ SiO ₄ (s) + 2CO ₂ (g) 2CaCO (s) + SiO ₂ (s) (3)

Typically, CO ₂ is introduced as a gas phase which dissolves in an infiltration medium such as water. The dissolution of CO2 forms acidic carbonic forms (such as carbonic acid, H ₂ CO ₃ ), which lowers the pH of the solution. A weakly acidic solution incongruently dissolves calcium from the calcium silicate phases, then carbon dioxide is converted into aqueous carbonate ions. Calcium can be leached from calcium-containing amorphous phases by a similar mechanism. The released calcium cations and aqueous carbonate groups (such as HCO ₃ ^- , CO2 ^{3 -} and Ca(HCO3) ₂ ) lead to the precipitation of insoluble solid carbonates. Silicon compounds during the course of chemical reactions (1)-(3) are converted into SiO ₂ (s) and are mineral particles.

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CaCO ₃ resulting from these or any other CO2 carbonation reactions described herein may exist as one or more of several substances that crystallize in various forms of CaCO ₃ (eg, calcite, aragonite, and vaterite). The CaCO ₃ particles are preferably in the form of calcite, but may also be present as aragonite or vaterite or as a combination of two or three substances crystallizing in different forms (e.g. calcite/aragonite, calcite/vaterite, aragonite/vaterite or calcite/aragonite /vaterite).

Any suitable grade of CO2 can be used depending on the desired carbonization result. For example, industrial grade CO2 with a purity of about 99%, which is commercially available from various industrial gas companies such as Praxair, Inc., Linde AG, Air Liquide, etc., can be used. The CO2 for supply can be stored in large pressurized tanks as liquid carbon dioxide contained at such a temperature that the required saturation vapor pressure is maintained, for example, approximately 300 psi. inch. This gas is then piped into the CO2 curing (carbonization) housing or chamber. In the simplest system, CO2 is forced through the housing at a controlled rate, sufficient to force out ambient air in the housing. In general, the purge time will depend on the size of the chamber or housing and the CO ₂ gas flow rate. In many systems, this purge process can be completed in minutes to get the CO ₂ concentration to a reasonable level so that curing can then take place. In simple systems, CO ₂ gas is then introduced into the system at a predetermined rate to maintain a CO ₂ concentration sufficient to initiate the curing reaction.

Carbonization, for example, can be accomplished by reacting with CO2 using a controlled hydrothermal liquid phase sintering (HLPS) process to create bonding elements that hold the various components of the composite material together. For example, in preferred embodiments, CO2 is used as a reactive agent, leading to the reaction of CO2 and the creation of binders in the resulting composite materials with a carbon footprint that is unparalleled in any existing manufacturing technology. The HLPS process is thermodynamically driven by the free energy of the chemical reaction(s) and the decrease in surface energy (area) caused by crystal growth. The kinetics of the HLPS process proceed at a reasonable rate at low temperature because a solution (aqueous or non-aqueous) is used to transport reactive species instead of using a high melting point liquid or high temperature crystalline medium.

Together, the bonding elements form an interconnected bonding matrix that provides a strong connection and holds the composite material together. For example, microstructural binders may be a binder containing a core of unreacted calcium silicate phase that does not contain carbonate, completely or partially surrounded by a silicon shell of various thicknesses, which is completely or partially enclosed in particles of CaCO ₃ ; a bonding element comprising a silicon core formed by the carbonation of a calcium silicate phase to form a carbonate, wholly or partly surrounded by a silicon shell of varying thickness, which is wholly or partly enclosed in CaCO ₃ particles; a bonding element comprising a silicon core formed by carbonation of a calcium silicate phase to form a carbonate and completely or partially enclosed in CaCO ₃ particles; a binder containing a core from a phase that does not provide the formation of carbonate, completely or partially enclosed in particles of CaCO ₃ ; a connecting element containing a multi-phase core consisting of silicon formed by carbonization of the calcium silicate phase, providing the formation of carbonate, and partially reacted calcium silicate, and the multi-phase core is completely or partially surrounded by a silicon shell of various thicknesses, which is completely or partially enclosed in CaCO3 particles; a connecting element containing a multi-phase core, consisting of a phase that does not provide the formation of carbonate, and partially reacted calcium silicate, and the multi-phase core is completely or partially surrounded by a shell of silicon of various thicknesses, which is completely or partially enclosed in CaCO ₃ particles; a binder containing particles of partially reacted calcium silicate without a distinct core and a shell of silicon enclosed in particles of CaCO ₃ ; and a binder containing porous particles without a distinct shell of silicon, enclosed in particles of CaCO ₃ .

The silicon-rich sheath typically varies in thickness within the bonding element and typically varies from about 0.01 to about 50 microns from bonding to bonding element. In some preferred embodiments, the silicon-rich shell has a thickness in the range of about 1 to about 25 microns. The term silicon-rich generally refers to a silicon content that is significant among the components of the material, eg, the silicon concentration is greater than about 50% by volume. The remainder of the silicon shell consists primarily of CaCO3, eg 10% to about 50% CaCO3 by volume.

The silicon-rich shell may also include inert or unreacted particles, such as from 10% to about 50% melilite by volume. The silicon-rich shell typically has a transition from a portion consisting primarily of silicon to a portion containing primarily CaCO ₃ . Silicon and

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CaCO ₃ may be present as mixed or isolated regions. The silicon-rich shell also has varying silicon content, typically ranging from about 50% to about 90% by volume from binder to binder (eg, from about 60% to about 80%). In some embodiments, the silicon-rich shell typically has a silicon content in the range of about 50 to about 90% by volume and a CaCO ₃ content in the range of about 10 to about 50% by volume. In some embodiments, the silicon-rich shell has a silicon content in the range of about 70 to about 90% by volume and a CaCO ₃ content in the range of about 10 to about 30% by volume. In some embodiments, the silicon-rich shell has a silicon content in the range of about 50 to about 70% by volume and a CaCO ₃ content in the range of about 30 to about 50% by volume.

The silicon-rich shell may surround the core with varying degrees of coverage anywhere from about 1% to about 99% (eg, from about 10% to about 90%). In some embodiments, a silicon-rich shell surrounds the core with less than about 10% coverage. In some embodiments, a silicon-rich cladding of various thicknesses surrounds the core with a coverage greater than about 90%.

The connecting element can be of any size and any regular or irregular, solid or hollow structure, which may be somehow determined by the choice of raw materials and the manufacturing process, taking into account the intended application. Exemplary structures include cubes, cuboids, prisms, disks, pyramids, polyhedra or polyhedral particles, cylinders, spheres, cones, rings, tubes, crescents, needles, fibers, filaments, flakes, spheres, subspheres, beads, granules, oblong bodies, rods , scales, etc.

The plurality of binders may have any suitable average particle size and size distribution depending on the desired properties and performance of the composite article. In some embodiments of the invention, for example, a plurality of binders have an average particle size in the range

from approximately 1 to about 100 micron (For example, from about 1 up to about 80 micron, from approximately 1 before approximately 60 micron, from approximately 1 before approximately 50 micron, from approximately 1 before approximately 40 micron, from approximately 1 before approximately thirty micron, from approximately 1 before approximately 20 micron, from approximately 1 before approximately 10 micron, from approximately 5 before approximately 90 micron, from approximately 5 before approximately 80 micron, from approximately 5 before approximately 70 micron, from approximately 5 before approximately 60 micron, from approximately 5 before approximately 50 micron, from approximately 5 before approximately 40 micron, from approximately 10 before approximately 80 micron, from approximately 10 before approximately 70 micron, from approximately 10 before approximately 60 micron, from approximately 10 before approximately 50 micron, from approximately 10 before approximately 40 µm, from about 10 before about 30 micron or

about 10 to about 20 µm).

The interconnected network of binding elements (bonding matrix) may also include a plurality of large or small filler particles, which may be made of any suitable material, have any suitable particle size and size distribution. In some preferred embodiments of the invention, for example, the filler particles are made from a calcium carbonate-rich material such as limestone (eg ground limestone). In some materials, the filler particles are made from one or more materials based on SiO ₂ or silicates, such as quartz, mica, granite and feldspar (eg ground quartz, ground mica, ground granite, ground feldspar).

In some embodiments, the filler particles may include natural, synthetic, and recyclable materials such as glass, recyclable glass waste, coal slag, fly ash, calcium carbonate rich material, and magnesium carbonate rich material.

In some embodiments, the plurality of filler particles have an average particle size in the range of about 5 to about 7 mm (e.g., about 5 to about 5 mm, about 5 to about 4 mm, about 5 to about 3 mm, from about 5 to about 2 mm, about 5 µm to about 1 mm, about 5 µm to about 500 µm, about 5 µm to about 300 µm, about 20 µm to about 5 mm, about 20 µm to about 4 mm , from about 20 µm to about 3 mm, from about 20 µm to about 2 mm, from about 20 µm to about 1 mm, from about 20 to about 500 µm, from about 20 to about 300 µm, from about 100 µm to about 5 mm, about 100 µm to about 4 mm, about 100 µm to about 3 mm, about 100 µm to about 2 mm, or about 100 µm to about 1 mm).

The weight ratio of binders to filler particles can be any suitable ratio depending on the intended use of the composite article. For example, the weight ratio of binders to filler particles may be in the range of about (50 to 99): about (1 to 50), e.g., about (60 to 99): about (1 to 40), about (from 80 to 99): about (1 to 20), about (90 to 99): about (1 to 10), about (50 to 90): about (10 to 50) or about (50 to 70): about (30 to 50). In some embodiments of the invention, depending on the application, the weight ratio of binders to filler particles can be in the range of about (10 to 50): about (50 to 90), for example, about (30 to 50): about (50 up to 70), about (from 40 to 50): about (from 50 to 60).

Preforms suitable for curing in accordance with the principles of the present invention typically have significant porosity. When a preform is molded from a material that produces carbonate, CO ₂ must diffuse throughout the preform so that it can react with the chemical components of the preform at all depths and in sufficient volume to create the desired physical and chemical properties inside the carbon dioxide-saturated product. Because the diffusion of CO2 gas is much faster than the diffusion of CO2 dissolved in water or any of its associated aqueous forms, it is desirable that the pores of the preform be opened to facilitate diffusion of CO2 gas through them. On the other hand, the presence of water may be necessary to facilitate the carbonate formation reaction. For example, in relation to calcium silicate, as described in the document, the dissolution of CO 2 forms acidic compounds (such as carbon dioxide, H ₂ CO ₃ ), which leads to a decrease in the pH of the solution. A slightly acidic solution dissolves calcium species incongruently from the calcium silicate phases. The released calcium cations and dissociated carbonate particles can lead to the formation of the binders described above. The amount of water contained in the preforms is chosen in such a way as to ensure adequate diffusion of carbon dioxide, as noted above. For example, in accordance with certain non-limiting embodiments of the invention, the preform may contain water in an amount of 2 to 5% by weight.

Obtaining a liquid mixture to obtain one or more blanks.

The liquid mixture can be obtained or otherwise produced for one or more preforms having the desired geometric shape and dimensions. There are no particular restrictions on suitable shapes or sizes of blanks. For example, blanks can be provided in the form of paving stones, concrete blocks, roof tiles, concrete slabs, wet cast slabs and hollow core concrete slabs, aerated concrete products, foam concrete products, aerated concrete wall stones, porous concrete panels. Likewise, a particular process or technique for molding the liquid mixture into a preform having the desired geometry and dimensions is not particularly limited. Any conventional molding technique may be used and is intended to be used within the scope of the present invention. Suitable forming methods include, but are not limited to, casting, forming, fiber casting, pressing, extrusion and/or foaming. As one specific, non-limiting example, the conventional pressing technique as described above and illustrated in FIG. 12.

Regardless of the particular technology used for molding, according to some aspects of the present invention, molding can be carried out using one or more supports, such as support 40 in FIG. 1-2. The support can assist in the formation of blanks in many possible ways. For example, the liquid mixture is subjected to pressure on the surfaces of the support to facilitate the molding process. However, the special role of the support in the molding process is not so limited. Thus, the support can be used as a separate element, in addition to the actual pressing means, whereby, after the blanks have already been formed into separate elements, the formed blanks can also then be placed on the surface of the support. A number of different possible uses of the support in the molding process are also possible and provided by the principles of the present invention.

According to some possible embodiments of the present invention, the supports may be in the form of what are known in the art as pressure plates. Such press plates may be formed from a variety of materials as long as they provide the required degree of rigidity to support one or more preforms on their surface. Suitable materials include plastics, metals and composite materials. According to one embodiment of the present invention, the support may be formed, at least in part, from metal. It is contemplated that the support may be made entirely of a metal alloy, or possibly a composite material including a metal component. Regardless of this, according to this embodiment, the support can be made electrically conductive. This feature has the advantage of allowing heating and efficient transfer of thermal energy to the preforms in subsequent curing steps. In some embodiments, the metal support may be heated using electrocontact heating techniques to raise the temperature of the blanks located on its surface.

Pre-curing of one or more blanks.

In accordance with some embodiments of the present invention, one or more blanks

- 9 043300 are optionally subjected to a partial or pre-curing process. The main criterion for developing an appropriate partial or pre-curing procedure is to ensure that one or more preforms have sufficient strength to be removed from one or more supports and remain substantially undamaged. As an additional possible objective or criteria for developing an appropriate partial or pre-curing procedure, is to ensure that one or more blanks have sufficient strength to support the weight of several additional blanks stacked on top of them, such as a body of stone, for the bottom row of a palletized cube of blanks formed for final curing as described later in this document.

As mentioned earlier, the ability to remove blanks from their supports before curing is complete provides a number of advantages and disadvantages. First, the supports, or press plates, can be returned more quickly for use in subsequent press and production operations, resulting in efficiency gains in that fewer press plates need to be used for production to achieve the same production volume. . Secondly, the carbonate forming cementitious concrete compositions of the present invention benefit from maximum exposure to the gaseous reactant (eg carbon dioxide) as well as controlled moisture loss. The presence of a large surface of the workpiece in contact with the surface of the support or pressing plate prevents both the entry of gaseous reagent into the workpiece and the release of moisture from it. Removing blanks from supports or press plates can increase and improve the efficiency of further curing operations. Thirdly, the early removal of the workpiece from their supports allows them to be assembled into a stack having a given geometric shape. This stack can take the form of a cube or other geometric figure tightly folded from blanks. Subjecting such a tightly packed cube or other shape to further curing operations may be advantageous compared to curing preforms placed on supports individually in terms of moisture retention/loss of building material properties and heat retention by the preforms during further curing operations. Fourth, early removal of the blanks from their supports allows them to be stacked for transport after final curing, eliminating the need for a post-processing step.

The strength of the partially or pre-cured preforms can be characterized by any appropriate quantity such as tensile strength, compressive strength, or both. As a non-limiting example, one or more preforms may be partially or pre-cured to a compressive strength of about 2000 to about 5000 psi. inch or from about 2400 to about 4500 psi. inch measured using ASTM C140. Minimum strength, at least about 2000 psi. inch is preferred to provide the workpiece with sufficient strength to be machined without substantially damaging the product. On the other hand, partial or pre-curing of preforms to achieve compressive strength well in excess of 5000 psi. inch, may be disadvantageous in terms of reducing the amount of water contained in the preform, which may prevent additional curing operations and limit the final compressive strength of the cured product (for example, at least about 8000 psi).

According to some embodiments of the invention, partial or pre-curing of preforms includes introducing the preforms and one or more supports into a pre-curing chamber, and in the case of preforms formed from a carbonate-forming cement/concrete composition, exposing the preforms and their supports to an atmosphere containing carbon dioxide. , air or a mixture thereof, for a given period of time. The specific conditions used in the chamber may vary depending on the design of the chamber itself, the chemical nature of the components that form the cement/concrete composition of the blanks, the desired degree of pre-cured strength, etc. Generally speaking, in some non-limiting examples, the partial or pre-curing procedure may be carried out at one or more of the following operating modes: from about 4 to about 200°C, from about 50 to about 130°C, or from about 60 up to about 85°C; curing time from about 60 to about 600 minutes, from about 60 to about 360 minutes, from about 60 to about 300 minutes, from about 60 to about 240 minutes, from about 60 to about 180 minutes, from about 60 to about 120 minutes, or about 60 to about 90 minutes; pressure from about 0.01 to about 0.04 psig. inch, relative humidity from about 1 to about 80% and a CO ₂ concentration from about 1 to about 99%.

According to one additional embodiment, the supports 40 may be made of a conductive material such as metal and the supports may be heated by a suitable technique such as heating with an electrical heating system. This additional heating of the supports can occur during the entire pre-curing time. During this heating, the preforms are pre-cured, or the supports may only be heated for a portion of the total pre-curing time, such as during the initial ramp-up period (eg, the first 1 hour of pre-curing). In accordance with this additional embodiment of the invention, the possibility of increasing the temperature of the workpieces 10 is provided by heating the supports 40 in contact with them.

Additional optional and non-limiting principles for the partial or pre-curing process for one or more preforms and their supports may include one or more of:

(1) flow rate of carbon dioxide through the pre-curing chamber: about 1 to about 250 L/min, about 10 to about 125 L/min, or about 40 to about 80 L/min;

(2) CO ₂ gas temperature at the pre-curing chamber inlet: about 4 to about 225°C or about 90 to about 100°C;

(3) continuous operation temperature of the pre-curing chamber: about 4 to about 200°C, about 50 to about 130°C, or about 60 to about 85°C;

(4) pressure in the pre-curing chamber: about 0.05 to about 1.0 inches of water, about 0.3 to about 0.7 inches of water, or about 0.4 to about 0.5 inches of water ;

(5) time to reach 50°C in the pre-curing chamber: up to about 1 hour, or about 20 minutes, or less;

(6) time to reach 70°C in the pre-curing chamber: up to about 3 hours, or about 90 minutes, or less;

(7) time to reach 30 to 40% relative humidity (RH) in the pre-curing chamber: up to about 1 hour, or about 30 minutes, or less;

(8) time to reach 10% relative humidity in the pre-curing chamber: about 90 minutes, or about 60 minutes, or less;

(9) time to reach 5% relative humidity in the pre-curing chamber: about 2.5 hours, or about 2 hours, or less;

(10) residual water (remaining in the paving stones at the end of the partial or pre-curing process) as a percentage by weight of the individual paving stone: about 0.5 to about 3%, about 1 to about 2.5%, or about 1.2 to about 1.6%;

(11) compressive strength (measured using ASTM C140) of stones at the end of partial or pre-cure: about 1500 to about 8000 psi. inch, from about 2000 to about 5000 psi. inch or about 2500 to about 3500 psi. inch.

The specific arrangement of the partial or pre-curing chamber itself is not particularly limited as long as it is capable of providing appropriate partial or pre-curing conditions for the preforms and their supports.

According to one illustrative and non-limiting example, partial or pre-curing 100 may be provided with the components and design features schematically and generally illustrated in FIG. 4. As shown in the figure, the partial or pre-curing apparatus 100 may include a pre-curing chamber 120. The pre-curing chamber 120 may be of any suitable shape or size and may be made of any suitable material. In some non-limiting examples, the pre-curing chamber 120 may be made of a hard material such as metal, ceramic, or plastic. In particular cases, the pre-curing chamber 120 may be made of a metallic material such as aluminium. According to additional embodiments of the invention, the pre-curing chamber may be made of a material having insulating properties to improve heat retention within it. Alternatively, the pre-curing chamber may be made of a metallic material, such as aluminum, and additionally comprise an insulating material. In accordance with a further embodiment of the invention, the pre-curing chamber 120 may be made of a flexible material. The flexible material may take any suitable shape, but preferably has some degree of heat resistance and at least resists penetration into the material of gaseous reactants contained in the interior of the pre-cure chamber 120. According to one embodiment of the invention, the flexible pre-cure chamber 120 may be formed from woven material coated with polymer. The pre-curing chamber 120, however formed, has a hollow interior cavity with a predetermined interior volume of the chamber, as shown in the CV of FIG. 4.

As shown further in FIG. 4, the blanks 10, together with their supports 40, are placed inside the pre-cure chamber 120, and a door or end cap (not shown) is used to seal the blanks 10 and their supports 40 within the pre-cure chamber so that operating conditions within the chamber can be controlled. pre-curing 11 043300. Exemplary pre-curing chamber conditions are detailed above. In some aspects, a support system 130, such as shelving/shelving systems, may be additionally provided within the pre-curing chamber 120 to accommodate and position the preforms 10 and their supports 40 during partial or pre-curing. The pre-curing chamber 120 may optionally be provided with a suitable gas circulation system to provide an atmosphere within the pre-curing chamber. When used to partially or pre-cure a carbonate-forming cement/concrete composition, apparatus 120 includes appropriate features to introduce CO ₂ into the interior of the pre-cure chamber. Such structural elements may include gas inlets 140 and gas outlets 150, as shown further in FIG. 4. It should be understood that both the location and the number of gas inlets 140 and/or gas outlets 150 may vary depending on the size of the pre-curing chamber, desired flow rates, and so on. In some non-limiting examples, pre-curing chamber 120 has 1-16, 1-12, 1-8, or 1-4 gas inlets 140. According to further exemplary embodiments, gas inlets 140 may be arranged in any suitable manner. For example, one or more gas inlets 140 may be located near the bottom of the pre-curing chamber 120. This arrangement may be advantageous because the gas introduced through the gas inlets 140 may be heated. When the heated gas enters the interior of the pre-cure chamber 120, it tends to rise vertically towards the top of the pre-cure chamber and thus naturally diffuse into the preforms 10 located inside the pre-cure chamber. The heated gas naturally moves to one or more gas outlets 150, which may optionally be provided at a location near the top of the pre-curing chamber 120.

According to another embodiment, as shown in FIG. 5, pre-cure chamber 120 and items loaded therein for partial or pre-cure can be designed such that the internal volume (CV) of pre-cure chamber 160 120 is only slightly larger than the total volume of preforms and their supports (SV) loaded. into it, as shown schematically in the figure. Thus, for example, pre-curing chamber 120 may be designed to have a ratio of chamber internal volume (CV) to preform/support volume (SV) of from about 1.05 to about 1.15. This design of the chamber pre-curing 120 allows you to more effectively control its modes of operation. This, in turn, makes it possible to achieve optimal curing conditions more quickly and complete the overall partial or pre-curing process in a shorter period of time compared to chambers having a less efficient design.

After completion of the partial or pre-curing process, the blanks 10 and their supports 40 are removed from the pre-curing chamber and the blanks 10 are removed from the supports 40. The blanks 10 may be removed from the supports 40 either manually or using any suitable device or equipment. In some examples, blanks 10 can be removed from supports 40 using a conventional automatic palletizer (not shown), and blanks 10 are placed in a predetermined geometric shape, such as a cube. This example is, of course, indicative, as any number of suitable geometries are possible, with or without the aid of a mechanical device or equipment. Suitable geometries formed by the ejected blanks 10 may be a cube, a pyramid, a cone, a 3D truncated cone, a cylinder, a 3D pentagon, a 3D hexagon, a 3D heptagon, a 3D octagon, or a 3D nonagon. According to some particular embodiments of the invention, the number of blanks 10 obtained in one partial or preliminary curing process is sufficient to form one or more of the above geometries. As an embodiment, blanks 10 may be obtained from several partial or pre-batch curing operations, assembled, and used to form one or more of the aforementioned geometries. It is contemplated that, within the principles of the present invention, any suitable number of partially or pre-cured preforms 10 may be assembled and used to form one or more of the aforementioned geometries. According to illustrative and non-limiting examples, 480 or more or 540 or more blanks can be assembled to form the aforementioned geometric figure, which is then subjected to further curing operations as a single structure. In accordance with additional special cases, the blanks can be paving stones, and the collection of blanks can form a cube of paving stones.

Curing chamber and process characteristics.

A collection of pre-cured preforms assembled into one or more of the above geometries can then be further cured together as one

- 12 043300 or several unified structures. One such stack 170 is schematically illustrated in FIG. 6 in the form of a three-dimensional cube located on an additional platform 180, such as a pallet. As previously mentioned, any suitable number of precured preforms can be used to form such a configuration. Non-limiting examples include 480 or more pre-cured blanks or 540 or more pre-cured blanks. The main criterion for the development of an appropriate curing process is that it provides pre-cured preforms with the desired strength characteristics at the end of the curing step. The strength of the cured products can be characterized by any appropriate value, such as tensile strength, compressive strength, or both. By way of example, without limitation, one or more cured articles may be cured to a compressive strength of about 8,000 to about 17,000 psi. inch, from about 9000 to 15000 psi. inch or at least from about 9200 psi. inch measured using ASTM C140. Minimum strength of at least about 8000 psi. inch is preferred to provide the cured product with sufficient strength to meet certain industry standards used in the specific application for which the cured product is intended, such as paving stone, slabs, and the like. Curing to such an extent that it provides strength values significantly higher than the accepted standard minimum strength is uneconomical and unnecessary.

In accordance with some particular cases of the invention, the curing of blanks having a certain geometric shape includes the introduction of a stack 170, optionally located on a platform 180, into the curing chamber, and in the case of pre-cured blanks formed from a cement/concrete composition that provides the formation of carbonate, exposure of the blanks to an atmosphere containing carbon dioxide, air or a mixture thereof, for a specified period of time. The specific conditions used in the chamber may vary depending on the design of the chamber itself, the chemical nature of the components that form the cement/concrete composition of the blanks, the desired degree of strength, etc. According to some non-limiting examples, the curing process can be carried out at one or more of the following conditions: from about 4 to about 200°C, from about 50 to about 30°C, from about 60 to about 95°C, from about 88 to about 95°C; curing time from about 6 to about 24 hours; pressure from about 0.01 to about 0.04 psig. inch, relative humidity from about 1 to about 80% and a CO ₂ concentration from about 1 to about 99%.

Additional optional and non-limiting curing modes for the production of cured articles may include one or more of the following:

(1) carbon dioxide flow rate in the curing chamber: about 1 to about 250 L/min, about 10 to about 125 L/min, or about 50 to about 80 L/min;

(2) temperature of CO2 gas entering the curing chamber: about 4 to about 225°C, about 90 to about 40°C, or about 110 to about 20°C;

(3) continuous operation temperature of the curing chamber: about 4 to about 200°C, about 50 to about 130°C, or about 88 to about 95°C;

(4) curing chamber pressure: about 0.05 to about 1.0 inches of water, about 0.3 to about 0.7 inches of water, or about 0.5 inches of water;

(5) time to reach 50°C in the curing chamber: up to about 2 hours, or about 60 minutes, or less;

(6) time to reach 75°C in the curing chamber: up to about 5 hours, or about 150 minutes, or less;

(7) time to reach 95° C. in curing chamber: up to about 10 hours, or about 4 hours, or less;

(8) time to reach 30 to 40% relative humidity in the curing chamber: up to about 4 hours, or about 30 minutes, or less;

(9) time to reach 10% relative humidity in the curing chamber: up to about 6 hours, or about 100 minutes, or less;

(10) time to reach 5% relative humidity in the curing chamber: up to about 2.5 hours, or about 2 hours, or less;

(11) residual water (remaining in the paving stone or concrete at the end of the curing process) in wt % of an individual stone: about 0.1 to about 2%, about 0.3 to about 1.5%, or about 0 .2 to about 0.9%;

(12) compressive strength (measured using ASTM C140) of products at the end of the curing process: about 8,000 to about 17,000 psi. inch or from about 9,000 to about 15,000 psi. inch.

Curing a stack of preforms together as a single structure (e.g., 170) provides certain benefits and advantages that are not provided by conventional curing methods that typically carry out the entire curing operation on preforms located on the surface of a support or pressure plate (e.g., 10, 40). Such benefits include, but are not limited to:

- 13 043300 (1) the temperature distribution profile of a single structure is more uniform compared to the interior of the chamber loaded with preforms stacked on supports, and the supports act as physical separators and insulators between different layers of preforms;

(2) the relative humidity profile of a single structure is more uniform compared to the interior of a chamber loaded with workpieces stacked on supports, and the supports and workpieces located on them are more susceptible to changes in the composition of the gas flow from level to level and in different areas of the interior of the chamber ;

(3) the distribution of water vapor within a single structure as a whole tends to be more uniform and resistant to overdrying of the outer surfaces and areas of the workpieces compared to workpieces laid on supports; and (4) dense stacking of blanks to form a single structure having a certain geometric shape, provides a minimum difference between the internal volume of the chamber (CV) and the volume of the stack of blanks (SV), which allows for greater efficiency and control of the interior of the chamber.

The specific design of the curing chamber itself is not particularly limited as long as it is capable of providing appropriate curing conditions for the stack of preforms. According to one particular embodiment of the invention, curing can be carried out in the same chamber as the pre-curing process. Thus, the curing chamber may have the same structure and features as the pre-curing chamber as previously described, and the previous description of the features for it is the same. For example, the curing chamber may have the same features and may be made of the same materials as the previously described chamber illustrated schematically in FIG. 4. To the extent necessary to accommodate the stack of blanks (eg, 170), the support system or rack 130 used to accommodate the supports 40 may not be included or removed from the interior of the chamber 120. Moreover, as previously discussed above, the curing chamber can be designed in such a way that its internal volume (CV) is only slightly larger than the volume of the stack of blanks (SV). In this regard, referring to FIG. 5, element 120 may refer to a curing chamber, and element 160 may schematically represent a stack of preforms 170 and any additional platform 180. In some embodiments of the invention, the ratio of the internal volume of the curing chamber 120 to the volume of the stack of preforms, or CV/SV, is from about 1 .05 to about 1.15. As previously described, minimizing this ratio allows for better and more efficient control of the curing chamber 120. As shown in FIG. 7, according to some alternative embodiments of the invention, chamber 120 may be enlarged or designed with sufficient volume to accommodate multiple stacks of preforms 170A, 170B, 170C. Each stack of preforms 170A-170C may be provided with a structural element to render it movable within chamber 120. Any suitable technique may be provided for this. In one example, rails 135 may be laid along the bottom 145 of chamber 120, and platforms 180 are provided with wheels 155 that allow them to be mounted on and moved on rails 135 so that platforms 180 and stacks of blanks 170 can move along rails 135 within the chamber. 120 from one end of the chamber to the other. Where possible, adjacent platforms 180/stacks 170 are located close to each other and possibly connected to each other 165 like train cars. This close proximity minimizes the difference between the internal volume of the chamber (CV) and the total volume of the sample platforms 180/stack 170 (SV).

In accordance with some embodiments of the invention, the curing may be performed in a separate chamber, different from the chambers for the partial or pre-curing stage. The following will describe some additional design features of the curing chambers and operating conditions in accordance with aspects of the present invention.

Vertical straight-through chamber (VBUF) and curing process specifications.

As previously described and shown in FIG. 4, one or more gas inlets 140 may be provided in the side(s) of the chamber. Alternatively, the curing chamber is constructed such that it has a permeable feature at the bottom or floor of the chamber that allows heated reactant gas (eg, containing CO ₂ gas) to enter the preform stack from the bottom thereof, and the heated reactant gas passes upward through workpiece pores.

In FIG. 8 shows a special case of such an arrangement. As shown, device 200 includes a chamber 210, shown in an exploded isometric view, which includes a floor or bottom surface 220. A permeable member 230 is provided in the floor or bottom surface 220 of chamber 210. The permeable member 230 may be made from any suitable material. and have any suitable shape. According to one embodiment of the invention, the permeable element 230 is made in the form of a steel lattice. As shown in FIG. 8, a gaseous reactant, such as gaseous CO ₂ or a mixture of air or another gas and CO ₂ , is introduced through the permeable member 230 and flows upward through the platform 180 and through the stack of preforms 170 as indicated by the arrows depicted in FIG. 8. As the heated gas rises, it cools slightly as it permeates the stack of preforms, thus providing an in situ thermal gradient so that the chemical reactant gas flows from the hotter regions (i.e. from below) to the upper cooler regions. zones. Thus, fast heating modes are possible in chamber 210. Chamber 210 may include one or more gas outlets at its top (eg, FIG. 4, 150).

The chamber 210 may also be designed to have only a slightly larger internal volume (CV) than the volume of the workpiece stack 170 and its support 180 disposed therein (SV). This feature is schematically illustrated in Fig. 5. Thus, in accordance with this embodiment, the ratio (CV/SV) of the internal volume of the curing chamber (CV) to the volume of the sample (SV) is preferably from about 1.05 to about 1.15. Minimizing this ratio allows effective mode control within chamber 210.

In accordance with another additional embodiment of the invention, the VBUF chamber 210 can also be increased in size so that it can accommodate a plurality of stacks of blanks 170 and their additional platforms 180. In accordance with this embodiment of the invention, a plurality of stacks of blanks 170 and their additional platforms are preferably placed tightly and close together to reduce the CV/SV ratio. For example, the CV/SP ratio with this arrangement is within the previously described range of about 1.05 to about 1.15.

According to a further embodiment of the invention, the device shown in FIG. 7 can be modified using the VBUF concept by constructing the floor 145 of the chamber 120 with a large permeable element 230 such as a steel grate. Alternatively, the floor 145 can be modified by providing a plurality of spaced apart permeable elements 230.

These embodiments provide the arrangement shown in FIG. 7, with the added benefit of the previously described vertical upward flow of reactant gas, which facilitates curing of the preforms.

Additional and preferred features of the VBUF curing chamber for the production of cured preforms may include one or more of the following:

(1) flow rate of carbon dioxide into the VBUF curing chamber: about 1 to about 250 L/min, about 10 to about 125 L/min, or about 50 to about 80 L/min;

(2) VBUF curing chamber inlet CO ₂ gas temperature: about 4 to about 250°C, about 90 to about 200°C, or about 140 to about 150°C (VBUF inlet gas temperature means gas temperature on the bottom surface of the platform 180/stack 170, which is on the permeable element 230;

(3) VBUF camera continuous operating temperature: about 4 to about 200°C, about 50 to about 120°C, or about 80°C to about 98°C;

(4) VBUF chamber pressure: about 0.05 to 1.0 inches of water, or about 0.3 to about 0.7 inches of water, or about 0.5 inches of water;

(5) time to reach 50°C in the VBUF chamber: up to about 20 minutes, or about 10 minutes, or less;

(6) time to reach 75°C in the VBUF chamber: up to about 1 hour, or about 30 minutes, or less;

(7) time to reach 90° C. in the VBUF chamber: up to about 2 hours, or about 1 hour, or less;

(8) time to reach 30 to 40% relative air humidity (RH) in the VBUF chamber: up to about 1 hour, or about 30 minutes, or less;

(9) time to reach 10% relative humidity in the VBUF chamber: up to about 90 minutes, or about 30 minutes, or less;

(10) Time to reach 5% relative humidity in the VBUF chamber: up to about 2.5 hours, or about 1 hour, or less.

Vertical bottom-up direct-flow continuous curing chamber (CC-VBUF) and characteristics of the curing process.

The present invention also contemplates further modifications to the aforementioned VBUF camera design. One such modified VBUF 200' circuit is shown in FIG. 9. As shown in the figure, the modified VBUF chamber 210' is provided with a modified chamber floor 220' and a modified vent 230'. In accordance with some additional aspects, a moving conveyor with a carrier grate or grate 230' as the precured surface of the work holder 10 forms the bottom of the CC-VBUF chamber. The movement of the conveyor can be continuous or intermittent. The precured blanks 10 are placed on the grate/grate 230' in a single layer. Thus, unlike the previous embodiments described here, after the preforms have been subjected to the pre-curing process, they are removed from their supports 40 but are not assembled or assembled into any particular post-curing shape as a single structure. Preferably they are placed on the conveyor 230' in a single layer with close

- 15 043300 location for further curing in CC-VBUF. This form, in the form of a single layer of pre-cured blanks 10 in the CC-VBUF chamber, allows curing to be completed with

CO2 in much less time. For example, curing of pre-cured preforms 10 can be completed in 6 hours or less. The preferred ratio of CV to SV of a VBUF chamber is the same as that of a VBUF chamber (ie, CV/SV = about 1.05 to about 1.15).

The pre-cured blanks to be cured enter from one side of the CC-VBUF chamber and the conveyor moves them in the direction of the horizontal arrows shown in FIG. 9 to move the cured products to the other side of the chamber. According to some additional embodiments, the cured articles can then be collected by a suitable device and prepared for shipment. According to one example, the cured articles may be assembled by a stacking machine and stacked to form a geometric shape such as a cube. Geometric figure 170 may be formed on support 180 to facilitate transportation.

The chemical reagent gas (e.g. CO2 or a mixture of air and/or another gas and CO2) is introduced from the bottom of a grate or grate, in principle identical in design to that used in the operation of the VBUF chamber, as indicated by the vertical arrows in FIG. 9. The speed at which the conveyor belt 230' moves can be used to determine the total curing time and hence the total residence time of the articles in the CC-VBUF chamber 210'. Alternatively, the conveyor 220' may move the products 10 to a specific location within the chamber 210', stop for a predetermined time, and then begin its movement to allow the products 10 to exit the chamber 210'. except for a fast and short workpiece entry and exit on each side of the CC-VBUF 210'. Minimizing the CV/SV ratio (eg, CV/SV = about 1.05 to about 1.15) makes it easier to maintain an even distribution of temperature and relative humidity in chamber 210'. The carbon dioxide flow rate, temperature and relative humidity in the CC-VBUF 210' chamber are the same or the same as those indicated above for the VBUF 210 chamber.

According to a further embodiment of the invention, the device shown in FIG. 7 can be modified using the CC-VBUF principle described above by forming the floor 145 of the chamber 120 as a movable conveyor 220'. In other words, rails 135 and wheels 155 can be replaced by a movable conveyor 220' having a gas-permeable belt 230'. This design change provides the arrangement shown in FIG. 7, with the added benefit of the above-described vertical upward flow of the gaseous reactant, which facilitates curing of the preforms. After the completion of the main curing phase, regardless of the specific conditions, chamber design, or methods used, the cured products are prepared for shipment or delivered to the customer. This particular step of the process covers a wide range of activities specific to the production of cured preforms. For example, the cured articles may simply be moved to a specific plant location for the final removal of the cured articles from the plant in which they are manufactured for transport to a customer. In accordance with another embodiment, the notification may be sent to a third party that performs the process of retrieving and transporting the cured articles to the customer. Such notices are intended to help you understand this stage. The dispatch of a stack of cured articles to a customer does not in any way imply that the actual delivery or transport of the cured articles takes place at this stage.

In view of the foregoing, it is clear that a number of advantages of the invention are provided and other advantages are achieved.

Since various changes can be made to the methods and compositions described above without departing from the spirit of the invention, it is intended that all materials contained in the above description should be interpreted as illustrative and not restrictive. It is intended that the present invention cover any possible set of features of the invention, regardless of the materiality of those features. Any numerical values expressing the quantities of ingredients, components, reaction conditions, etc. used in the description should be interpreted as covering the exact numerical values defined here, as well as modified taking into account the preposition about. While the numerical ranges and parameters set forth herein are approximations, the numerical values given are intended to be the most accurate. However, any numerical value may inherently contain error or inaccuracy, as is evident from the standard deviation found in the respective measurement methods. None of the specifics herein should be interpreted as a reference to 35 U.S.C. § 112 § 6 unless the term means is explicitly used.

Claims (13)

1. A method for forming a plurality of cured concrete products, each of which has the compressive strength of a cured product, including: the introduction of a fluid mixture with the composition of the concrete components in a variety of forms; molding said fluid mixture within a plurality of molds with one or more supports, thereby forming a plurality of product blanks; partially curing the article blanks to a value sufficient to provide a compressive strength that is lower than the compressive strength of the cured article, thereby forming a plurality of pre-cured blanks; combining at least a portion of a plurality of pre-cured blanks to form a stack having a given geometric configuration, said geometric configuration being a three-dimensional shape, and combining the pre-cured blanks is removing them from the surface of said one or more supports and stacking these pre-cured blanks one on top of the other; introducing the obtained stack of pre-cured blanks into the curing chamber; curing said stack of precured slabs to a value sufficient to achieve compressive strength of the cured article, thereby obtaining a stack of cured articles having said geometric configuration, wherein the step of curing the precured slabs comprises exposing the precured slabs to carbon dioxide for a period of time from about 6 to about 24 hours and temperatures from about 60 to about 95°C. 2. The method of claim 1, further comprising sending a stack of cured articles having a predetermined geometric configuration to a customer. 3. The method of claim 1, wherein said composition comprises one or more carbonate producing cement components and one or more aggregates, said one or more cement components optionally containing calcium silicate and said fluid mixture optionally containing water. . 4. The method according to claim 1, in which at least one of the stages of introduction and molding includes one or more of the stages: pouring, vibrating, pressing, extrusion or foaming. 5. The method of claim 1 wherein the one or more supports is a pressure platen. 6. The method of claim 1, wherein the plurality of blanks form paving stones, concrete blocks, roof tiles, hollow core concrete slabs, wet cast slabs, concrete slabs, foam concrete products, aerated concrete products, aerated concrete masonry elements or ventilated panels. 7. The method of claim 1 wherein the compressive strength of the precured preforms is from about 2000 psi. inch (about 13.8 MPa) to about 5000 psi. inch (about 34.5 MPa), measured in accordance with ASTM C140, and the compressive strength of the cured product is at least about 8000 psi. inch (approximately 55.2 MPa), measured in accordance with CASTMC 140. 8. The method of claim 1, wherein the step of partially curing the preforms further comprises heating at least one support. 9. The method of claim 1, wherein the precured preforms are removed from one or more supports, optionally by an automatic palletizer or material handling and loading system. 10. The method according to claim 1, in which the given geometric configuration is a cube. 11. The method of claim 1, wherein the step of partially curing the preforms or the step of curing the pre-cured preforms comprises introducing the preforms or pre-cured preforms into the pre-curing chamber or curing chamber, respectively, and further comprising introducing heated gas into the pre-curing chamber or curing chamber from a location located near the bottom of the pre-curing chamber or curing chamber, as well as removing heated gas from the pre-curing chamber or curing chamber from a location located near the top of the pre-curing chamber or curing chamber. 12. The method of claim 1, wherein the step of curing the precured preforms further comprises introducing the preforms into the curing chamber, placing the stack of precured preforms on a movable platform to move the stack of precured preforms from one end of the curing chamber to the opposite end. 13. The method of claim 1, wherein the step of partially curing the preforms or the step of curing the pre-cured preforms comprises introducing the preforms or pre-cured preforms into a pre-curing chamber or curing chamber, respectively, wherein - 17 043300 blanks or pre-cured blanks and their substrates have a sample volume, and the pre-curing chamber or curing chamber has an internal volume, and in which the ratio of the internal volume of the pre-curing chamber or curing chamber to the volume of the sample is from about 1.05 to about 1 ,15.