WO2025165296A1

WO2025165296A1 - Carbon dioxide-based cementitious product for buildings and soil improvement

Info

Publication number: WO2025165296A1
Application number: PCT/SG2025/050047
Authority: WO
Inventors: Jian Chu; Zheng Zhang; Kangda Wang; Shifan WU
Original assignee: Nanyang Technological University
Current assignee: Nanyang Technological University
Priority date: 2024-01-31
Filing date: 2025-01-21
Publication date: 2025-08-07
Anticipated expiration: 2026-07-31

Abstract

A method of making a carbon dioxide-based cementitious product includes: providing a calcium chloride solution and an ammonia source; and mixing the calcium chloride solution and the ammonia source with a bacteria solution (e.g., of Sporosarcina pasteurii) to obtain a cementitious product, wherein the cementitious product includes amorphous calcium carbonate. A cementitious product including an amorphous calcium carbonate (ACC) and a bacteria distributed thereon may be provided in the form of a slurry or a powder. A use of the cementitious product to treat a soil may include: forming the cementitious product from a mixture of calcium chloride and a bacteria solution; and adding the cementitious product to the soil to form a treated soil, wherein the cementitious product includes ACC. The treated soil includes calcite and the aggregate particles bonded together. The cementitious product may also be used to make building components.

Description

CARBON DIOXIDE-BASED CEMENTITIOUS PRODUCT

FOR BUILDINGS AND SOIL IMPROVEMENT

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority of Singapore application no. 10202400293W filed January 31 , 2024, the contents of which are hereby incorporated by reference in entirety for all purposes.

TECHNICAL FIELD

[0002] The present disclosure relates to buildings and soil improvement, and more particularly to the methods of building and soil improvement using a cementitious product that can involve lower carbon dioxide emissions.

BACKGROUND

[0003] The construction of various building elements and infrastructure, whether underground or above the ground) often require prior preparation of the soil or ground. This is particularly critical in foundation, excavation, and tunnelling works in soft ground. Grouting is often required for seepage control in soil or rocks Conventionally, Portland cement is used, e g., in jet grouting or deep cement mixing for soil treatment. However, the production of Portland cement generates a substantial amount of carbon dioxide (CO2) emissions.

SUMMARY

[0004] In one aspect, the present application discloses a method of making a carbon dioxidebased cementitious product. The method includes: providing a calcium chloride solution and an ammonia source; and mixing the calcium chloride solution and the ammonia source with a bacteria solution to obtain a cementitious product, wherein the cementitious product includes amorphous calcium carbonate.

[0005] The bacteria solution may include any one or more of the following: Sporosarcina pasteurii (DSM33), Bacillus megaterium, and a Pseudomonas species.

[0006] In another aspect, the present application discloses a cementitious product including an amorphous calcium carbonate (ACC) and a bacteria distributed thereon, wherein the cementitious product is in the form of a slurry or a powder.

[0007] In yet another aspect, the present application discloses a use of the cementitious product to treat a soil with aggregate particles, including: forming the cementitious product from a mixture of calcium chloride and a bacteria solution, and adding the cementitious product to the soil to form a treated soil, wherein the cementitious product includes amorphous calcium carbonate, and wherein the treated soil includes calcite and the aggregate particles bonded together.

[0008] In yet another aspect, the present application further discloses a use of the cementitious product to make a building component, including: forming the cementitious product from a mixture of calcium chloride and a bacteria solution; and providing a cement mixture of the cementitious product and aggregate particles in a mould to cast the building component, wherein the cementitious product includes amorphous calcium carbonate, and wherein the building component includes calcite and the aggregate particles bonded together.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In the following description, various embodiments of the invention are described with reference to the following drawings.

[0010] FIG. 1 is a schematic diagram illustrating a method to prepare a cementitious product; [001 1] FIG. 2 is a schematic diagram of a set-up to form a test column using the ACC- biocement of the present disclosure;

[0012] FIG. 3 compares the unconfmed compressive (UC) strength of the ACC-biocement with that of Porland cement;

[0013] FIG. 4 shows the pH change during the curing or treatment of the ACC-biocement;

[0014] FIG. 5 shows the calcium carbonate in the test column;

[0015] FIG. 6 shows an SEM image of the crystal transformation process at 0 hour of reaction time;

[0016] FIG. 7 shows an SEM image of the crystal transformation process after 8 hours of reaction time;

[0017] FIG. 8 shows an SEM image of the crystal transformation process after 16 hours of reaction time;

[0018] FIG. 9 shows an SEM image of the crystal transformation process after 24 hours of reaction time;

[0019] FIG. 10 shows an SEM image of the crystal transformation process after 48 hours of reaction time; and

[0020] FIG. 11 shows an SEM image of the crystal transformation process after 96 hours of reaction time.

[0021] FIG. 12 to FIG. 16 illustrates a method of soil improvement using the cementitious product of the present disclosure;

[0022] FIG. 17 is a schematic drawing illustrating the construction of a road pavement using the cementitious product of the present disclosure; and

[0023] FIG. 18 is a schematic flow diagram illustrating a method of building and soil improvement according to embodiments of the present disclosure. DETAILED DESCRIPTION

[0024] The following detailed description is made with reference to the accompanying drawings, showing details and embodiments of the present disclosure for the purposes of illustration. Features that are described in the context of an embodiment may correspondingly be applicable to the same or similar features in the other embodiments, even if not explicitly described in these other embodiments. Additions and/or combinations and/or alternatives as described for a feature in the context of an embodiment may correspondingly be applicable to the same or similar feature in the other embodiments.

[0025] In the context of various embodiments, the articles “a”, “an” and “the” as used with regard to a feature or element include a reference to one or more of the features or elements.

[0026] Tn the context of various embodiments, the term “about” or “approximately” as applied to a numeric value encompasses the exact value and a reasonable variance as generally understood in the relevant technical field, e g., within 10% of the specified value.

[0027] As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

[0028] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. As used herein, the singular ‘a’ and ‘an’ may be construed as including the plural “one or more” unless apparent from the context to be otherwise.

[0029] Terms such as “first” and “second” are used in the description and claims only for the sake of brevity and clarity, and do not necessarily imply a priority or order, unless required by the context.

[0030] Some methods may be described in terms of steps merely to aid understanding and/or for convenient reference. The delineation between one step and another step may be merely for convenient reference in the present disclosure. It will be understood that in actual implementation there may not be a clear division or transition from one step to another subsequent step. There may be a certain amount of overlap among the steps and/or more than one step may occur or be performed concurrently in time, etc.

[0031] Reference to amorphous calcium carbonate (ACC) conventionally refers to an unstable phase of calcium carbonate. According to various embodiments of the present disclosure, a stable form of ACC is formed to serve at least to support or enable a distribution or a distributed deposition of a bacteria thereon. Examples of the bacteria include but are not limited to one or more selected from the following: Sporosarcina pasteurii (DSM33), Bacillus megaterium, and a Pseudomonas species. For the sake of brevity and convenience, in the present disclosure, a stable form of ACC with one or more bacteria species disposed thereon is referred to herein as a cementitious product or an ACC-biocement.

[0032] The viability of ACC-biocement was experimentally demonstrated. To aid understanding, FIG. 1 illustrates an exemplary system 200 for making the cementitious product of the present disclosure.

[0033] A calcium chloride solution and an ammonia source were provided (step 210) to a first chamber and mixed (step 220). In some of the experiments, carbide sludge and ammonium chloride were provided to a first chamber and mixed. In some examples, the calcium chloride may be extracted or provided from a process of mixing a calcium carbide sludge with an ammonium chloride solution.

[0034] The resulting solution may be filtered using vacuum filtration (step 230) to remove solid particles. The filtrate or filtered solution may also be referred to as a clarified solution.

[0035] A bacteria solution is injected to the clarified solution (step 240). In some examples, the mixture of calcium chloride and ammonia source may be filtered to obtain a clarified solution before the injection of the bacteria solution. In some examples, the bacteria may be any one or more selected from the group including: Sporosarcina pasteurii (DSM33), Bacillus megalerium, and a Pseudomonas species.

[0036] The mixture of the bacteria solution, the calcium chloride and the ammonia source are mixed in a second chamber (step 250). The first chamber and the second chamber may be in controllable fluid communication, e g., via one or more valves and one or more pumps to control the fluid of materials from the first chamber to the second chamber.

[0037] In some examples, the mixture in the second chamber may include 1 mol/L (mole per liter) of calcium chloride; 2 mol/L of ammonia; and 10⁵ CFU/ml (colony-forming unit per milliliter) to 10⁹ CFU/ml of bacteria solution.

[0038] The mixture from the second chamber is atomized (e.g., the mixture of the bacteria solution, calcium chloride, and ammonia source) to obtain an aerosol (step 270). Tn some embodiments, the mixture may be atomized by providing pressurized carbon dioxide (CO2) to the mixture (step 260). In some examples, the pressurized carbon dioxide may be provided at a pressure of 350 kilopascals (kPa). In some examples, filtration is performed using a 0.22 pm nylon filter paper (step 290).

[0039] The aerosol is dried to obtain the cementitious product in a particulate form or a powder form (step 280). The dry form of the cementitious product may be formed into a slurry. It was found that the dry form of the cementitious product contained ACC in a sufficiently stable form such that the cementitious product may be conveniently and efficiently stored and transported.

[0040] According to another aspect of the disclosure, a cementitious product is produced by a process that may be described by equation (1) below:

Bacteria+2NH₃+CO₂+CaCl2+H2O Bac-CaCO₃ (Dried ACC)+2NH₄Cl . . . (1)

[0041] In some embodiments, the residual ammonium chloride obtained after filtration may be recycled (step 212) for use to extract calcium carbonate from carbide sludge. The process 200 as a whole minimizes the industrial waste produced and can contribute towards lower carbon emissions.

[0042] In another aspect, the present disclosure provides a method to treat a soil with aggregate particles. The method includes casting a cement mixture of one or aggregates particles and the cementitious product to form a cast article in a mould. The treatment includes curing the cast article in the mould using a cementation solution.

[0043] In another aspect, properties of an article formed from the cementitious product may be further enhanced. In some embodiments, the article may be cured or treated by application of a cementation solution.

[0044] In some embodiments, a cementation solution may be provided (e.g., poured onto or deposited on) to the article being moulded or cast In some embodiments, the cementitious product may be provided in conjunction with a cementation solution and provided to permeate through the soil that is under treatment. It is envisioned that there are many ways of using the ACC-biocement, e.g., in place of Portland cement, in combination with a cementation solution to improve a cementitious product that contains ACC-biocement, etc. In some examples, the cementation solution includes a source of calcium and urea. In some experiments, a cementation solution of 0.5M calcium and urea was used to achieve significant improvement in the properties of the resulting article.

[0045] There is no limit to the types and amount of aggregates that are selected for use with the cementitious product and/or the cementation solution. In some embodiments, the one or more aggregate particles selected from the group consisting of sand, clay, steel slag, and a coarse aggregate.

[0046] In an example 400 as shown in FIG. 2, 2.5 % of the cementitious product was mixed with a silica sand in a blender at a consistent velocity for a duration of 10 minutes. The mixture 410 of the silica sand and the cementitious product was cast into an acrylic mould or a PVC column 420. The mould may have a diameter of 50 mm and a height of 1 10 mm. A cementation solution 430 including 0.5M calcium chloride and urea was circulated by a peristaltic pump at a rate of lOml/min so that the cementation solution permeates the mixture of sand (silica) mixed with the cementitious product (e.g., ACC-bacteria). The resulting column 450 was tested at intervals, e.g., for a duration of 8 to 96 hours, to investigate the development of strength with continuous supply of calcium ions and urea.

[0047] It is believed that the bacteria present on the ACC particles of the cementitious product absorbed the urea and initiated the hydrolysis of the urea, leading to the production of carbonate, as depicted in Equation (2) below.

CO(NH₂)₂ -2H₂O -^2NH₄+ - COj²~ ... (2)

[0048] The negatively charged Extracellular Polymeric Substances (EPS) excreted by bacteria is believed to attract calcium ions. This, in turn, induced regional saturation of calcium ions and pH elevation, facilitating the nucleation of calcium carbonate on the amorphous calcium carbonate particles, as shown in Equation (3) below.

ACC ~ Ca²⁺ + CDs²' ~^ACC ~ CaCO₃ ... (3)

[0049] The ACC particles may act as seeds for the growth of stable calcite, resulting in continuous precipitation. In some embodiments, the transformed calcite crystals may serve as a bonding agent, connecting the sand particles together, leading to an increase in strength (FIG. 3) and a reduction in permeability.

[0050] The mixture of the cementitious product and the sand was treated to a different duration from 8 hours to 672 hours (28 days) and the unconfined compressive (UC) strength of the mixture was measured. Referring to FIG. 3, an early strength of 1.7 MPa was achieved in 8 hours. The UC strength showed a continuous increase over time, reaching 8.5 MPa after 48 hours (2 days) of treatment (corresponding to the formation of calcite composites as seen in the SEM image of FIG. 10). [0051 ] UC tests on the same sand treated with Portland cement with the same cement content of 2.5% were also carried out. The UC strength of the cement treated sand was almost zero after 8 hours of curing and was only 0.1 MPa after 2 days’ curing. The cementitious product (ACC) treated sand gained full strength around 10 MPa after 7 days of curing whereas the Portland cemented treated sand only achieved the full strength after 28 days of curing. Hence, the curing time for the cementitious product treated sand can be greatly reduced by 75% compared to the traditional cement.

[0052] As shown in FIG. 4, the significant improvement in strength does not negatively impact the local environment. There was a negligible pH value fluctuation between 7 to 7.5, indicating no significant impact on local environment.

[0053] X-ray diffraction (XRD) analysis was performed to quantitatively examine the crystal transformation of calcium carbonate in the sand column, and the results are as shown in FIG. 5. The results indicate that the total calcium carbonate content increased with curing time, suggesting that bacteria attached to the cementitious product continuously hydrolyze urea to precipitate a large amount of calcium carbonate. Further, the ratio of calcite gradually increased from 25.4% at 8 hours to 92.8% at 96 hours of curing time. The vaterite content dropped from 7.9% to 1.9%, meaning at least 75% of the vaterite was transformed to calcite after the 96 hours of curing.

[0054] The crystal transformation of the calcium carbonate in the sand column was also visually inspected by taking SEM images. FIG. 6 to FIG. 11 are SEM images of the crystal transformation process taken at: (a) 0 hour; (b) 8 hours; (c) 16 hours; (d) 24 hours; (e) 48 hours; and (f) 96 hours of reaction time, respectively. Referring to the SEM images, the cementitious product covers the sand grains at the beginning (0 hours), rounded vaterite formation dominates after 8 hours. This suggests that during this period, mineral precipitates generated through bacteria activities initiate nucleation upon the nano-scale ACC particles of the cementitious product, which are subsequently transformed into micro-scale vaterite structure. Tn the 16' ¹¹ hour, nearly half of the vaterite have been transformed into calcite, effectively overlaying the sand surfaces. The time frame spanning from 40 hours to 48 hours supports the transformation of vaterite into calcite, while simultaneously fostering the expansion of existing calcite structures. This phenomenon results in the development of well-graded calcite arrangements, characterized by dimensions ranging from 1 micrometer to 50 micrometers, and these arrangements are interconnected to establish numerous robust contact points, thereby enhancing the overall strength. During the subsequent treatment period of 3 days to 4 days, the continuous introduction of fresh precipitates facilitates the growth of both vaterite and calcite, promoting their subsequent maturation into calcite, while also enabling their progression into larger calcite structures. This sequential process effectively fills pores between sand particles, layer by layer, linking sand particles through varying sizes of rhombohedral calcite formations.

[0055] In yet another aspect of the present disclosure, a method of forming a column is provided. The method may include a step of 610 of driving a casing 612 into a soil 602 (FIG.

12). The method may include a step 620 of placing a geotextile sock 622 inside the casing (FIG.

13). The method may include a step 624 of providing a mixture in the geotextile sock 622, in which the mixture includes sand and the cementitious product. The method may include a step 630 of removing the casing 632 after curing the mixture, leaving behind a column 644 of the cementitious product 634 embedded in the soil (FIG. 14).

[0056] In some embodiments, the method 640 may further include a step 642 of injecting the cementation solution to the column and curing the cementitious product to produce a column characterized by an enhanced strength (FIG. 15).

[0057] The method described above may be applied to enhance the bearing capacity of the geotextile encased columns (GEC). GEC have been used as a method to treat soft soil. Untreated, the sand inside the GEC may not be properly compacted and the axial bearing capacity of the GEC columns is limited. The cementitious product can be used to treat the sand inside the GEC columns in order to enhance the bearing capacity of the GEC columns. The strength of the improved soil 652 can be increased using the present method such that a building or such structure 654 may be built on the “improved” soil (FIG. 16).

[0058] FIG. 12 to FIG. 16 may also be referred to for another example of the treatment process. Firstly, a GEC is stalled by driving in a steel casing into the soft soil and then placing a seamless cylindrical closed bottom geotextile “sock” inside the casing before sand (or gravel) mixed with the cementitious product is poured into the geotextile lined column. A GEC is formed after the extraction of the steel casing. Secondly, the sand (or gravel) in the column is further solidified by injecting a solution containing a 0.5M cementation solution into the sand column. The rate of injection depends on the volume of the sand column and also the permeability of the bottom soil layers. In this example, the geotextile “sock” may be left in the ground.

[0059] Application of the cementitious product in prefabrication of building materials [0060] Various precast units such as bricks, beams, plates, and column may be manufactured by mixing the aggregate particles such as sands, clay, steel slag and coarse aggregate, with the cementitious product and casting the mixture into the desired shapes using moulds.

[0061] An example is shown in FIG 17 which illustrates a method of constructing road pavement using the cementitious product of the present disclosure. The mixture 720 of the cementitious product and the aggregate particles such as sand or the other granular materials can be poured into a mould 710 followed by the densification using a concrete vibrator Then, a cementation solution 713 may be poured on top of the pavement until the cementation solution is 5 cm above the road pavement surface for curing. The casting of the pavement may take two days to complete. The method can effectively reduce the construction duration while ensuring comparable strength to be achieved. [0062] As schematically represented in FIG. 18, a method 100 according to embodiments of the present disclosure may include a formation of a cementitious product or ACC-biocement (step 110). The method 100 may further include an enhancement of the properties of an article formed using the cementitious product or ACC-biocement, including but not limited to an application of a cementation solution thereto (step 120).

[0063] Benefits

[0064] Based on the above, it can be appreciated that the processes of making and using the proposed cementitious product or the proposed cement would result in an overall general reduction in the total amount of carbon dioxide emissions, as compared to the production and use of Portland cement.

[0065] In some of the embodiments described above, e.g., by recycling sludge and other waste materials, it is possible to achieve a carbon negative cement. Examples of waste that can be used may include various industrial waste products that contain calcium.

[0066] At the same time, the proposed cementitious product or the proposed cement can be used in a wide range of applications, including but not limited to ground improvement, concreting, or both.

[0067] The proposed cementitious product or proposed cement was experimentally verified to have relatively low impact on the environment. For example, the pH value of sand treated with the proposed cementitious product fluctuated insignificantly between 7 and 7.5.

[0068] Advantageously, the experiments also indicated that the curing time for the proposed cement can be greatly reduced by 75%, as compared to conventional Portland cement.

[0069] Further, as described above, there is evidence of an effective promotion of the formation of calcite. These and other beneficial features may be implemented by way of various embodiments. [0070] According to various embodiments of the present disclosure, a method includes providing a calcium chloride solution and an ammonia source; and mixing the calcium chloride solution and the ammonia source with a bacteria solution to obtain a cementitious product, the cementitious product may include amorphous calcium carbonate.

[0071] In some embodiments, the method may further include mixing a calcium carbide sludge with an ammonium chloride solution to provide the calcium chloride solution and the ammonia source.

[0072] In some embodiments, the method may further include filtering the calcium chloride solution and the ammonia source to obtain a clarified solution before injecting the bacteria solution to the clarified solution.

[0073] In some embodiments, the bacteria solution may include any one or more of the following: Sporosarcinapasteurii (DSM33), Bacillus megaterium, and a Pseudomonas species. [0074] In some embodiments, the method may further include a step of atomizing a mixture of the bacteria solution with the calcium chloride solution and the ammonia source to obtain an aerosol.

[0075] In some embodiments, the step of atomizing may include providing pressurized carbon dioxide to the mixture.

[0076] In some embodiments, the pressurized carbon dioxide may be provided at a pressure of 350 kPa.

[0077] In some embodiments, the method may further include a step of drying the aerosol to obtain the cementitious product.

[0078] In some embodiments, the step of drying may include drying the aerosol with a hot air stream.

[0079] In some embodiments, the step of drying may produce the cementitious product in a powder form. [0080] Tn some embodiments, the method may further include obtaining a residual ammonium chloride solution; and recycling the residual ammonium chloride solution by using the residual ammonium chloride solution to mix with the calcium carbide sludge.

[0081] In some embodiments, the aerosol may be obtained from: 1 mol/L of the calcium chloride; 2 mol/L of the ammonia source, and 10⁵ CFU/ml to 10⁹ CFU/ml of the bacteria solution

[0082] In some embodiments, the method may further include mixing the cementitious product with any one or more aggregate particles selected from the group consisting of sand, clay, steel slag, and a coarse aggregate.

[0083] In some embodiments, the method may further include curing a cement mixture permeated with a cementation solution, the cement mixture including the cementitious product and one or more aggregate particles. The cementation solution may include a calcium source and urea, and a product of the curing may include calcite binding the one or more aggregate particles.

[0084] In some embodiments, the method may further include casting the cement mixture of one or more aggregate particles and the cementitious product to form a cast article in a mould; a step of immersing the cast article in the cementation solution; and curing the cast article in the mould before demoulding the cast article from the mould to form a precast article.

[0085] In some embodiments, the step of immersing may include pouring the cementation solution over the cast article to form a pavement, the cementation solution including 0.5M calcium and urea.

[0086] In some embodiments, the step of immersing may include injecting the cementation solution into the cement mixture of the one or more aggregate particles and the cementitious product, the cementation solution including 0.5M calcium chloride and urea. [0087] Tn some embodiments, the method may further include forming a column, including: driving a casing into a soil, placing a geotextile sock inside the casing; providing the cement mixture in the geotextile sock, the one or more aggregates of the cement mixture including sand; and removing the casing after the curing of the cement mixture.

[0088] In some embodiments, the cementitious product may include an amorphous calcium carbonate and a bacteria distributed thereon, the cementitious product may be in the form of a slurry or a powder.

[0089] In some embodiments, the cementitious product may be used to treat a soil with aggregate particles, including: forming the cementitious product from a mixture of calcium chloride and a bacteria solution, and adding the cementitious product to the soil to form a treated soil. The cementitious product may include amorphous calcium carbonate, and the treated soil may include calcite and the aggregate particles bonded together.

[0090] In some embodiments, the cementitious product may be used to make a building component, including: forming the cementitious product from a mixture of calcium chloride and a bacteria solution; and providing a cement mixture of the cementitious product and aggregate particles in a mould to cast the building component. The cementitious product may include amorphous calcium carbonate, and the building component may include calcite and the aggregate particles bonded together.

[0091] All examples described herein, whether of apparatus, methods, materials, or products, are presented for the purpose of illustration and to aid understanding, and are not intended to be limiting or exhaustive Modifications not involving inventive effort may be made by one of ordinary skill in the art without departing from the scope of the claimed invention.

Claims

1. A method comprising: providing a calcium chloride solution and an ammonia source; and mixing the calcium chloride solution and the ammonia source with a bacteria solution to obtain a cementitious product, wherein the cementitious product includes amorphous calcium carbonate.

2. The method as recited in claim 1, further comprising mixing a calcium carbide sludge with an ammonium chloride solution to provide the calcium chloride solution and the ammonia source.

3. The method as recited in claim 2, further comprising filtering the calcium chloride solution and the ammonia source to obtain a clarified solution before injecting the bacteria solution to the clarified solution.

4. The method as recited in any one of claims 1 to 3, wherein the bacteria solution comprises any one or more of the following: Sporosarcina pasteurii (DSM33), Bacillus megaterium, and a Pseudomonas species.

5. The method as recited in any one of claims 1 to 4, further comprising atomizing a mixture of the bacteria solution with the calcium chloride solution and the ammonia source to obtain an aerosol.

6. The method as recited in claim 5, wherein the atomizing comprises providing pressurized carbon dioxide to the mixture.

7. The method as recited in claim 6, wherein the pressurized carbon dioxide is provided at a pressure of 350 kPa.

8. The method as recited in any one of claims 5 to 7, further comprising drying the aerosol to obtain the cementitious product.

9. The method as recited in claim 8, wherein the drying comprises drying the aerosol with a hot air stream.

10. The method as recited in claim 8 or claim 9, wherein the drying produces the cementitious product in a powder form.

11. The method as recited in claim 3, further comprising: obtaining a residual ammonium chloride solution; and recycling the residual ammonium chloride solution by using the residual ammonium chloride solution to mix with the calcium carbide sludge.

12. The method as recited in claim 5, wherein the aerosol is obtained from: 1 mol/L of the calcium chloride; 2 mol/L of the ammonia source; and 10⁵ CFU/ml to 10⁹ CFU/ml of the bacteria solution.

13. The method as recited in any one of claims 1 to 12, further comprising: mixing the cementitious product with any one or more aggregate particles selected from the group consisting of sand, clay, steel slag, and a coarse aggregate.

14. The method as recited in any one of claims 1 to 13, further comprising: curing a cement mixture permeated with a cementation solution, the cement mixture including the cementitious product and one or more aggregate particles, wherein the cementation solution includes a calcium source and urea, and wherein a product of the curing includes calcite binding the one or more aggregate particles.

15. The method as recited in claim 14, comprising: casting the cement mixture of one or more aggregate particles and the cementitious product to form a cast article in a mould; a step of immersing the cast article in the cementation solution, and curing the cast article in the mould before demoulding the cast article from the mould to form a precast article.

16. The method of claim 15, wherein the step of immersing comprises pouring the cementation solution over the cast article to form a pavement, the cementation solution including 0.5M calcium and urea.

17. The method of claim 15, wherein the step of immersing comprises injecting the cementation solution into the cement mixture of the one or more aggregate particles and the cementitious product, the cementation solution including 0.5M calcium chloride and urea.

18. The method as recited in claim 14, further comprising: forming a column, comprising: driving a casing into a soil; placing a geotextile sock inside the casing; providing the cement mixture in the geotextile sock, the one or more aggregates of the cement mixture including sand; and removing the casing after the curing of the cement mixture.

19. A cementitious product made according to the method as recited in any one of claims 1 to 18, the cementitious product comprising an amorphous calcium carbonate and a bacteria distributed thereon, wherein the cementitious product is in the form of a slurry or a powder.

20. A use of the cementitious product of claim 19 to treat a soil with aggregate particles, comprising: forming the cementitious product from a mixture of calcium chloride and a bacteria solution; and adding the cementitious product to the soil to form a treated soil, wherein the cementitious product includes amorphous calcium carbonate, and wherein the treated soil includes calcite and the aggregate particles bonded together.

21. A use of the cementitious product of claim 19 to make a building component, comprising: forming the cementitious product from a mixture of calcium chloride and a bacteria solution; and providing a cement mixture of the cementitious product and aggregate particles in a mould to cast the building component, wherein the cementitious product includes amorphous calcium carbonate, and wherein the building component includes calcite and the aggregate particles bonded together.