Seawater concrete hydration process regulation and control method with carbon sequestration effect and seawater concrete

Abstract

The invention relates to a seawater concrete hydration process regulation and control method with a carbon sequestration effect, aiming at the problems of concentrated heat release, easy cracking and the like in early hydration of large-volume seawater concrete, the early hydration process is regulated and controlled by using CO2 in a mixing stage, the main hydration heat release peak is delayed by 0.5-3 hours, the peak value is reduced by 10-30%, the accumulated heat release in 72 hours is basically unchanged or slightly reduced, and the total hydration heat release is reduced by 10-30%. Therefore, the risks of thermal cracks and shrinkage cracks are reduced, and the carbon sequestration capacity is improved. The method comprises the following steps: adding a cementing material and aggregate into a closed reactor, and stirring until dry materials are uniformly mixed; air in the reactor is pumped out, and CO2 gas is injected into the reactor to reach preset air pressure; the method comprises the following steps: injecting seawater or artificial seawater into a reactor, uniformly mixing, enabling CO2 to be subjected to carbonation reaction with calcium and magnesium ions and hydration products in a system, and forming a compact shell layer on the surfaces of clinker particles and a slurry-aggregate interface by generated nano-scale CaCO3, calcium and magnesium carbonate and magnesium-containing calcium silicate hydrate; therefore, the main hydration heat release peak value of the seawater concrete is reduced and the peak value occurrence time is delayed.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a method for regulating the hydration process of seawater concrete that also has a carbon sequestration function, and seawater concrete. Background Technology

[0002] With the large-scale construction of coastal and marine engineering projects in my country, the demand for concrete in coastal and near-shore areas is increasing, and the direct utilization of marine resources in concrete has attracted widespread attention. Against this backdrop, using seawater as concrete mixing water can reduce freshwater usage and raw material transportation costs, improve seawater resource utilization, and alleviate the freshwater shortage problem in coastal areas to some extent.

[0003] However, seawater contains a high concentration of sodium. + Mg 2+ Cl - and SO4 2- Plasma. In the early stages of seawater-mixed concrete, these ions significantly accelerate the hydration process of cement clinker, causing the hydration peak to appear earlier and increasing the exothermic peak. While accelerated hydration is beneficial for the early strength development of concrete, for large-volume marine engineering components, excessive early exothermic heat can lead to concentrated internal temperature rise and increased temperature gradient, resulting in localized stress concentration and shrinkage cracking risks, severely impacting the long-term service performance and durability of the structure. Therefore, rationally controlling the early hydration process of seawater concrete and delaying the internal temperature rise of components is of great significance for reducing cracking, extending service life, and ensuring the safety and stability of coastal and marine engineering construction. On the other hand, cement clinker production itself is an industrial process with high carbon emission intensity. How to simultaneously achieve early hydration process control and carbon dioxide emission reduction in seawater concrete systems is a crucial scientific and engineering problem currently facing the development of green and low-carbon seawater concrete materials.

[0004] Current research has attempted to control the early hydration behavior of seawater concrete by adjusting the cementitious material system. For example, using a multi-component cementitious system with low early hydration activity or incorporating industrial solid waste can reduce early hydration heat release and control crack initiation and development. Studies have shown that simply adding mineral admixtures has limited effect on reducing the early hydration heat peak and often results in significant early strength loss, which is detrimental to early crack control and rapid structural commissioning. Furthermore, once the concrete material system is fixed during the design phase, it is difficult to flexibly adjust it according to different component cross-sectional dimensions, environmental conditions, and construction conditions during engineering construction, making it difficult to meet the fabrication needs of various types of marine engineering components.

[0005] Therefore, it is necessary to propose a new integrated technology for regulating the hydration process and reducing carbon in seawater concrete, so as to achieve controllable early hydration behavior and efficient CO2 sequestration of large-volume seawater concrete while taking into account the utilization of seawater resources. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems in existing seawater concrete, such as concentrated early hydration heat release, large temperature gradient, susceptibility to thermal and shrinkage cracks, inefficient CO2 utilization, and difficulty in adjusting the concrete material system during construction. This invention proposes a method for regulating the hydration process of seawater concrete that also functions as a carbon sink, and the resulting seawater concrete. Based on fully utilizing seawater resources, CO2 is introduced during the mixing stage to regulate the early hydration process of the cement system, reducing the heat release rate of the main hydration peak, mitigating temperature rise and shrinkage risks. The concrete material system is then adjusted during the construction stage to meet engineering needs. Simultaneously, the calcium in the cement-seawater system is utilized. 2+ Mg 2+ Plasma enables in-situ mineral CO2 sequestration, thereby enhancing the overall carbon sequestration capacity of concrete. This invention is applicable to the preparation and application of large-volume seawater concrete in coastal and marine engineering structures such as seawalls, breakwaters, port terminals, and offshore wind power foundations.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] On the one hand, the present invention provides a seawater concrete that combines hydration process regulation and carbon sequestration capabilities, comprising the following steps:

[0009] (1) Add cementitious materials and aggregates to a closed reactor with good airtightness according to the concrete mix ratio, and stir until the dry materials are evenly mixed.

[0010] (2) Close and seal the reactor, use a vacuum pump to extract the air from the reactor, and after the internal pressure stabilizes, inject CO2 gas into the reactor so that the CO2 gas pressure P inside the reactor meets the following condition: 0.5 MPa <P≤1.5MPa;

[0011] (3) Under the condition of keeping the CO2 pressure basically constant, seawater or artificial seawater prepared according to the actual seawater ion concentration is injected into the reactor and stirred until the mixture is uniform, so that CO2 dissolves in large quantities in the early stage and reacts with Ca in the system. 2 + Mg 2+ The hydration products undergo carbonation reactions, generating nano-sized CaCO3, calcium magnesium carbonate, magnesium-containing hydrated calcium silicate, and chlorinated sulfoaluminate to form a dense shell on the surface of clinker particles and at the slurry-aggregate interface. These shells then act as nucleation points during the subsequent deceleration period, refining the pore structure and densifying the slurry-aggregate interface transition zone.

[0012] This invention introduces CO2 into the concrete mixing stage, allowing it to dissolve in large quantities in seawater or artificial seawater in the early stages. CO2 directly participates in the early hydration process, altering the pore solution chemical environment and interfacial reactions. This delays the appearance of the main hydration exothermic peak by 0.5–3 hours and reduces the peak value by 10%–30%, while the long-term (e.g., 72 hours) cumulative hydration exothermic effect remains essentially unchanged or only slightly decreases. This effectively controls the early hydration process without significantly weakening early strength development. Simultaneously, significant mineral consolidation is achieved during the mixing stage, resulting in a high CO2 consolidation volume per unit volume in fresh concrete within 24 hours. The closed reactor design further enhances CO2 utilization and facilitates precise adjustment at predetermined pressures and flow rates in concrete mixing plants and precast yards.

[0013] In some embodiments, the cementitious material is composed of cement and mineral admixtures, wherein cement accounts for 60% to 90% of the total mass of the cementitious material and mineral admixtures account for 10% to 40% of the total mass of the cementitious material.

[0014] In some embodiments, the aggregate is any one or a combination of two or more of river sand, sea sand, or manufactured sand.

[0015] In some embodiments, the mineral admixture has pozzolanic activity, reducing the calcium hydroxide content in the system through a pozzolanic reaction and forming a low-alkalinity, high-polymerization-degree hydrated calcium silicate gel, which facilitates CO2 mineralization and Mg... 2+ The formation of magnesium-containing hydrated calcium silicate further provides a reaction interface.

[0016] In some embodiments, the mineral admixture includes one or more of fly ash, slag powder, and / or ultrafine silica fume.

[0017] In some embodiments, the artificial seawater includes the following components at mass concentrations (g / L): NaCl: 19.62–29.44; MgCl₂·6H₂O: 8.88–13.32; Na₂SO₄: 3.27–4.91; CaC₂: 0.93–1.39; KCl: 0.556–0.834; NaHCO₃: 0.161–0.241; and also includes corresponding soluble inorganic salts based on differences in trace ions / trace elements in seawater from different regions. The adjustable ion concentration of seawater or artificial seawater provides parameter adjustment space for hydration processes and CO₂ sequestration under different marine engineering environments, and its applicability covers a variety of large-volume coastal and marine engineering structures.

[0018] In some embodiments, in step (2), after the vacuum pump extracts the air inside the reactor to make the internal air pressure of the reactor not higher than 1000 Pa, CO2 gas is injected to ensure the purity of the internal CO2 and enhance the mass transfer rate at the interface between the CO2 gas phase and the cement paste.

[0019] In some embodiments, the CO2 is high-purity CO2 gas, and the stirring in step (3) is rapid stirring with a stirring rate of not less than 200 rpm and a stirring time of not more than 10 min. The total amount of mineralized CO2 accounts for 2% to 10% of the mass of the cementitious material. In this way, the participation of CO2 in the reaction process can be quantitatively limited from three dimensions: time, pressure, and CO2 input, so as to adjust the concrete material system during the engineering construction stage.

[0020] In some implementations, compared with seawater concrete without CO2 introduction, the seawater concrete prepared using the aforementioned seawater concrete hydration process control method exhibits a 0.5–3 hour delay in the appearance of the main hydration exothermic peak and a 10%–30% reduction in peak value in its hydration heat response index. This provides controllable indicators that can be judged engineeringly from the perspective of "hydration heat process – macroscopic temperature rise," achieving a clear correspondence between CO2 process parameters and the hydration process control effect.

[0021] On the other hand, the present invention provides a seawater concrete, which is prepared by mixing and hydration using the seawater concrete hydration process control method described above, which also has a carbon sink function.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) In this invention, CO2 is introduced during the concrete mixing stage. Through CO2 dissolution and early carbonation, the excessively rapid hydration of cement clinker during the accelerated period in the seawater environment is suppressed, the peak value of the main hydration exothermic peak is significantly reduced and the exothermic curve is smoothed. This is beneficial to reduce the temperature rise rate and internal-surface temperature difference of large-volume seawater concrete, and reduce the risk of thermal cracking and shrinkage cracking.

[0024] (2) Utilizing the abundant Ca in seawater 2+ Mg 2+ In addition, aluminum phase minerals in cementitious materials preferentially generate fine calcium carbonate, dolomite, magnesium-containing hydrated calcium silicate, and chlorinated sulfoaluminate products in the presence of CO2, which significantly improves the mineral retention efficiency of CO2, enabling fresh concrete to achieve a high CO2 retention per unit volume within 24 hours, thus realizing the coupling of marine concrete preparation process with carbon dioxide emission reduction.

[0025] (3) The carbonates and magnesium-containing hydrated calcium silicate gel generated in the early stage can serve as additional nucleation sites, allowing cement hydration products to continue to precipitate and settle during the deceleration period, further refining the pore structure and the dense paste-aggregate interface transition zone, thereby improving the concrete's impermeability, chloride ion intrusion resistance and overall durability while ensuring or slightly increasing the early compressive strength.

[0026] (4) The present invention adopts the method of introducing CO2 in the mixing stage to regulate the early hydration process. The process steps are similar to those of ordinary seawater concrete mixing process. It can be realized by simply adding a sealing and air supply module to the conventional mixing equipment. It has the advantages of good process adjustability, strong applicability, and easy promotion and application in coastal engineering component prefabrication yards and on-site mixing plants.

[0027] In summary, this invention combines three levels—"kinetic process + microstructure + macroscopic hydration thermal response"—to construct a complete mechanism chain for hydration process regulation and carbon sequestration synergy: Early stage: CO2 dissolution lowers the local pH value and consumes Ca(OH)2, inhibiting the accelerated and intense clinker hydration caused by seawater, thus reducing and smoothing the main peak; Mid-to-late stage: Early-formed carbonates and magnesium-containing hydrated calcium silicate serve as nucleation sites, promoting continuous hydration and ensuring 72 hours of cumulative heat release and strength development; Microstructure: The formation of a dense shell and a dense interface transition zone improves the concrete's impermeability and resistance to chloride ion intrusion, thereby achieving the controllable regulation of the early hydration process of seawater concrete and the synergistic unity of CO2 mineral sequestration. This is a method for regulating the hydration process of seawater concrete that also functions as a carbon sequestration agent. Attached Figure Description

[0028] The invention, its features and advantages will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0029] Figure 1 This is a graph showing the exothermic curves of the hydration process of seawater concrete under different artificially prepared seawater concentrations in Embodiment 1 of the present invention.

[0030] Figure 2 This is a cumulative heat release curve of the hydration process of seawater concrete under different artificially prepared seawater concentrations in Embodiment 1 of the present invention. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but these are not intended to limit the scope of the invention.

[0032] The execution order of actions, steps, etc. in the apparatus and methods shown in the claims, specification, and drawings can be implemented in any order, unless a specific order is explicitly specified, and as long as the output of the preceding processing is not used in the subsequent processing.

[0033] The reaction devices, reaction raw materials, detection instruments, etc. involved in the following examples are all commercially available. The detection methods used are prior arts that can be retrieved, and the technologies not detailed in the following effect examples are prior arts that can be retrieved.

[0034] The present invention first provides a method for regulating the hydration process of seawater concrete with carbon sequestration ability, which includes the following steps:

[0035] (1) Add the cementitious material and aggregate into a closed reactor with good airtightness according to the concrete preparation ratio, and stir until the dry materials are evenly mixed; preferably, the cementitious material consists of cement and mineral admixture, where the cement accounts for 60% - 90% of the total mass of the cementitious material, and the mineral admixture accounts for 10% - 40% of the total mass of the cementitious material; the aggregate is any one or a combination of two or more of river sand, sea sand or manufactured sand; further, the mineral admixture has pozzolanic activity, and reduces the calcium hydroxide content in the system through pozzolanic reaction and forms hydrated calcium silicate gel with low alkalinity and high polymerization degree, providing a reaction interface for the CO2 mineralization reaction and further generation of magnesium-containing hydrated calcium silicate. For example, the mineral admixture includes one or a combination of two or more of fly ash, slag powder and / or ultra-fine silica fume; 2+ For example, the mineral admixture includes one or a combination of two or more of fly ash, slag powder and / or ultra-fine silica fume;

[0036] (2) Close and seal the reactor, use a vacuum pump to evacuate the air inside the reactor, and after the internal air pressure is stable, inject CO2 gas into the reactor so that the CO2 air pressure P in the reactor satisfies: 0.5 MPa < P ≤ 1.5 MPa; preferably, after the vacuum pump evacuates the air inside the reactor to make the internal air pressure not higher than 1000 Pa, inject high-purity CO2 gas.

[0037] (3) Under the condition of keeping the CO2 air pressure basically unchanged, inject seawater or artificial seawater prepared according to the actual seawater ion concentration into the reactor, and stir rapidly (the stirring rate is not less than 200 rpm) until the mixture is evenly mixed, so that a large amount of CO2 dissolves in the early stage and reacts with Ca 2+ 、Mg 2+The hydration products undergo carbonation, generating nano-sized CaCO3, calcium magnesium carbonate, and magnesium-containing hydrated calcium silicate, which form a dense shell on the surface of clinker particles and at the slurry-aggregate interface. These shells act as nucleation points during the subsequent deceleration phase, refining the pore structure and densifying the slurry-aggregate interface transition zone. Preferably, the artificial seawater contains the following components at mass concentrations (g / L): NaCl: 19.62–29.44; MgCl2·6H2O: 8.88–13.32; Na2SO4: 3.27–4.91; CaC2: 0.93–1.39; KCl: 0.556–0.834; NaHCO3: 0.161–0.241; and includes corresponding soluble inorganic salts based on differences in trace ions / trace elements in seawater from different regions. Examples of such inorganic salts include halides, borates / boric acid, silicates, nitrates, or phosphates. The stirring time should not exceed 10 minutes, and the total mineralized CO2 content should account for 2% to 10% of the mass of the cementitious material.

[0038] The above-mentioned methods for regulating the hydration process of seawater concrete introduce CO2 into the mixing stage of seawater concrete, constructing a complete mechanism chain of hydration process regulation and carbon sink synergy: Early stage: CO2 dissolution reduces local pH value and consumes Ca(OH)2, inhibiting the rapid and intense hydration of clinker accelerated by seawater, reducing and smoothing the main peak; Middle and late stages: The carbonates and magnesium-containing hydrated calcium silicates generated in the early stage serve as nucleation sites, promoting continuous hydration and ensuring 72 hours of cumulative heat release and strength development; Microstructure: Formation of a dense shell and a dense interface transition zone, improving impermeability and resistance to chloride ion intrusion.

[0039] This invention also provides a seawater concrete, prepared by mixing and hydration using the seawater concrete hydration process control method described above. This seawater concrete exhibits high strength, high impermeability, and high resistance to chloride ion intrusion. Compared to seawater concrete without CO2 introduction, the seawater concrete prepared using the aforementioned seawater concrete hydration process control method shows a 0.5–3 h delay in the appearance of the main hydration exothermic peak and a 10%–30% reduction in peak value, while the long-term (e.g., 72 h) cumulative hydration exothermic response remains essentially unchanged or only slightly reduced.

[0040] To further aid in understanding the technical solution of this invention, several specific implementation examples are provided below to describe the technical solution of this invention in more detail.

[0041] Example 1

[0042] This embodiment uses silicate cement as an example to illustrate the specific implementation process of the seawater concrete hydration process control method that also has a carbon sink function in this invention.

[0043] The cementitious material used was PI 52.5 ordinary Portland cement, and the aggregate was any one or a combination of two or more of river sand, sea sand, or manufactured sand. Artificially prepared simulated seawater was used as mixing water, and CO2 gas was used as the carbonation gas source. The mass proportions of each component were as follows: 500 parts cementitious material, aggregate allocated according to the concrete design, 200 parts artificially prepared simulated seawater (two solutions, one with high ion concentration and one with low ion concentration, were prepared for comparative testing), and 30 parts CO2 gas for carbonation.

[0044] The preparation steps are as follows:

[0045] (1) Put the cementitious material and aggregate into a closed reactor and dry mix for 30 seconds to make the cementitious material and aggregate evenly mixed.

[0046] (2) Close the reactor and seal it, turn on the vacuum pump, and extract the air inside the reactor until the air pressure inside the reactor is not higher than 1000 Pa.

[0047] (3) Inject CO2 gas into the reactor to make the CO2 pressure inside the reactor reach 0.5~1.5 MPa; for example, use 1 MPa;

[0048] (4) Simulated seawater is continuously introduced into the reactor under rapid stirring, and the stirring time is controlled to be about 10 minutes to make the concrete mixture uniform.

[0049] (5) After stirring, open the exhaust valve to discharge the residual CO2 inside the reactor, then open the reactor cover, take out the mixture, and place it in a sealed bag or other sealed container to prevent the surface moisture from evaporating too quickly.

[0050] Figure 1 is a schematic diagram of the isothermal calorimetric test results of this embodiment. In the figure, A-M0, A-M1, and A-M2 represent samples mixed with pure water, low seawater concentration, and high seawater concentration, respectively, without CO2 treatment. C-M0, C-M1, and C-M2 represent samples mixed with pure water, low seawater concentration, and high seawater concentration, respectively, after CO2 carbonization treatment. The results show that, compared with seawater concrete without CO2 introduction, the peak value of the main hydration peak of the seawater concrete in this embodiment is reduced by about 20%. Figure 2 The cumulative heat release curve for 72 hours in this embodiment shows that the cumulative heat release for 72 hours is only slightly reduced. This indicates that in the seawater environment, CO2 stirring mainly plays an inhibitory and regulatory role in the early hydration process, and has little impact on the degree of hydration in the middle and late stages. This is beneficial to maintaining a relatively sufficient hydration reaction and strength development while controlling the early temperature rise and cracking risk.

[0051] The process in this embodiment is similar to that of ordinary seawater concrete mixing, and can be implemented simply by adding a sealing and air supply module to the mixing equipment.

[0052] Example 2

[0053] This embodiment provides a method for controlling the hydration process of seawater concrete that also functions as a carbon sink. The implementation process is similar to that of Embodiment 1, except that the cementitious material in this embodiment consists of cement and mineral admixtures, with cement accounting for 60%–90% of the total mass of the cementitious material and the mineral admixtures accounting for 10%–40%. The mineral admixtures exhibit pozzolanic activity, reducing the calcium hydroxide content in the system through a pozzolanic reaction and forming a low-alkalinity, high-polymerization-degree hydrated calcium silicate gel, which facilitates CO2 mineralization and Mg... 2+ Further, magnesium-containing hydrated calcium silicate is generated to provide a reaction interface. For example, the mineral admixture includes one or more combinations of fly ash, slag powder, and / or ultrafine silica fume. Taking a cementitious material composed of 75% cement and 25% mineral admixture, the mineral admixture is fly ash. Test results show that, compared with seawater concrete without CO2 introduction, the peak value of the main hydration peak of the seawater concrete in this embodiment is reduced by about 25%, and the cumulative heat release over 72 hours is reduced by 5%.

[0054] Example 3

[0055] This embodiment provides a seawater concrete, comprising cementitious materials, aggregates, seawater or artificially prepared seawater, CO2 gas, and possibly water-reducing agents and other admixtures. Its hydration process employs the seawater concrete hydration process control method described in Example 1 or Example 2. By adjusting parameters such as the concentration of ions in the seawater or artificially prepared seawater, the pressure of the CO2 gas, and the CO2 reaction time, the material system of the prepared seawater concrete can be adjusted. This provides parameter adjustment space for the hydration process and CO2 retention under different marine engineering environments and construction requirements, and its applicability covers various large-volume structures in coastal and marine engineering projects. The compressive strengths of several 72-hour hardened seawater concrete cubes were 21.3, 24.1, 26.9, 22.0, 23.7, and 24.9 MPa, respectively. Furthermore, the porosity of the 72-hour hardened seawater concrete decreased by 21.7%, 20.9%, and 22.1% (based on a control sample without CO2 introduction), respectively, and its chloride ion permeability decreased by 16.8%, 19.5%, and 22.7%, respectively.

[0056] As can be seen from the above description, this invention uses natural seawater or artificial seawater prepared according to the actual seawater ion concentration as mixing water, and systematically analyzes the Na in seawater. + Mg 2+ Cl⁻, SO₄ 2⁻ Based on the accelerating effect of plasma on the early hydration process and the resulting temperature rise and cracking problems, this paper proposes a control strategy that introduces CO2 and seawater ions synergistically during the mixing stage. This is achieved by utilizing the abundant Ca in seawater. 2+Mg 2+ In addition, aluminum phase minerals in cementitious materials preferentially generate fine CaCO3, dolomite, magnesium-containing hydrated calcium silicate, and chlorinated sulfoaluminate and other characteristic products under CO2 conditions, thus constructing a "seawater ion-hydration-carbonation" coupling mechanism.

[0057] This invention addresses key engineering problems in large-volume seawater concrete, such as concentrated early hydration heat release, large temperature gradient, susceptibility to cracking, and inefficient CO2 utilization. It proposes using CO2 to regulate the early hydration process during the mixing stage, delaying the main hydration heat release peak by 0.5–3 hours and reducing the peak value by 10%–30%, while maintaining or slightly reducing the cumulative heat release over 72 hours. This significantly reduces the temperature rise rate and temperature difference, lowering the risk of thermal and shrinkage cracks. Furthermore, the concrete material system is adjusted during the construction phase to meet engineering needs, while simultaneously improving overall carbon sequestration capacity. The seawater concrete of this invention possesses excellent properties such as high strength, high impermeability, and high resistance to chloride ion intrusion, making it particularly suitable for large-volume seawater concrete applications such as seawalls, breakwaters, port terminals, and offshore wind power foundations. It focuses on solving the integrated problem of hydration heat, temperature field, crack control, and carbon reduction in large-volume components. This invention achieves a synergistic unity of hydration heat regulation, durability improvement, and CO2 mineral sequestration without significantly increasing later-stage processes. It results in shorter construction periods and simpler construction processes, facilitating large-scale promotion in coastal prefabrication yards and mixing plants.

[0058] The preferred embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and the devices and structures not described in detail should be understood as being implemented in a conventional manner in the art. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the present invention. This does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention's technical solutions still fall within the protection scope of the present invention.

Claims

1. A method for regulating the hydration process of seawater concrete that also functions as a carbon sink, characterized in that, Includes the following steps: (1) Add cementitious materials and aggregates to a closed reactor with good airtightness according to the concrete mix ratio, and stir until the dry materials are evenly mixed. (2) Close and seal the reactor, use a vacuum pump to extract the air from the reactor, and after the internal pressure stabilizes, inject CO2 gas into the reactor so that the CO2 gas pressure P inside the reactor meets the following condition: 0.5 MPa <P≤1.5MPa; (3) Under the condition of keeping the CO2 pressure basically constant, seawater or artificial seawater prepared according to the actual seawater ion concentration is injected into the reactor and stirred until the mixture is uniform, so that CO2 dissolves in large quantities in the early stage and reacts with Ca in the system. 2+ Mg 2+ The hydration products undergo carbonation reactions, generating nano-sized CaCO3, calcium magnesium carbonate, magnesium-containing hydrated calcium silicate, and chlorinated sulfoaluminate to form a dense shell on the surface of clinker particles and at the slurry-aggregate interface. These shells then act as nucleation points during the subsequent deceleration period, refining the pore structure and densifying the slurry-aggregate interface transition zone.

2. The method for regulating the hydration process of seawater concrete with carbon sequestration function as described in claim 1, characterized in that, The cementitious material is composed of cement and mineral admixtures, wherein cement accounts for 60% to 90% of the total mass of the cementitious material, and mineral admixtures account for 10% to 40% of the total mass of the cementitious material.

3. The method for regulating the hydration process of seawater concrete with carbon sequestration function as described in claim 1, characterized in that, The aggregate is any one or a combination of two or more of river sand, sea sand, or manufactured sand.

4. The method for regulating the hydration process of seawater concrete with carbon sequestration function as described in claim 2, characterized in that, The mineral admixture exhibits pozzolanic activity, reducing the calcium hydroxide content in the system through a pozzolanic reaction and forming a low-alkalinity, high-polymerization-degree hydrated calcium silicate gel, which facilitates CO2 mineralization and Mg... 2+ The formation of magnesium-containing hydrated calcium silicate further provides a reaction interface.

5. The method for regulating the hydration process of seawater concrete with carbon sequestration function as described in claim 4, characterized in that, The mineral admixture includes one or more of fly ash, slag powder and / or ultrafine silica fume.

6. The method for regulating the hydration process of seawater concrete with carbon sequestration function as described in claim 1, characterized in that, The artificial seawater contains the following components with mass concentrations: NaCl: 19.62–29.44 g / L; MgCl2·6H2O: 8.88~13.32 g / L; Na2SO4: 3.27~4.91 g / L; CaC2: 0.93~1.39 g / L; KCl: 0.556~0.834 g / L; NaHCO3: 0.161~0.241 g / L; It also includes corresponding soluble inorganic salts based on the differences in trace ions / trace elements in seawater from different regions.

7. The method for regulating the hydration process of seawater concrete with carbon sequestration function as described in claim 1, characterized in that, In step (2), after the vacuum pump extracts the air from the reactor to ensure that the internal pressure of the reactor is not higher than 1000 Pa, CO2 gas is injected.

8. The method for regulating the hydration process of seawater concrete with carbon sequestration function as described in claim 1, characterized in that, The CO2 is high-purity CO2 gas. In step (3), the stirring is rapid stirring with a stirring rate of not less than 200 rpm and a stirring time of not more than 10 min. The total amount of mineralized CO2 accounts for 2% to 10% of the mass of the cementitious material.

9. The method for regulating the hydration process of seawater concrete with carbon sequestration function as described in claim 1, characterized in that, Compared with seawater concrete without CO2 introduction, the seawater concrete prepared by the seawater concrete hydration process control method has a 0.5-3h delay in the appearance time of the main hydration exothermic peak and a 10%-30% reduction in the peak value in the hydration thermal response index.

10. A type of seawater concrete, characterized in that, The seawater concrete with carbon sequestration function is prepared by mixing and hydration using the method for controlling the hydration process of seawater concrete as described in any one of claims 1 to 9.

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