Preparation method of activated muck doped carbon sequestration type seawater and sea sand concrete

Abstract

The invention belongs to the technical field of building materials, and particularly relates to a preparation method of activated muck doped carbon sequestration type seawater and sea sand concrete, which comprises the following steps: S1, excavating and taking soil as raw material muck, and drying the taken muck; s2, screening the muck in the step S1 to obtain muck powder, activating the muck powder through heat treatment calcination, mixing the heat activated muck powder with metakaolin and water glass, and stirring to form a heat activated muck mixture; s3, the sea sand is screened and mixed with the gravel particles, cement is added, and a cement-based mixture is obtained; s4, the activated muck mixture, the cement-based mixture, seawater, an additive and an admixture are mixed and placed in a sealed carbonization box body, and the carbon sequestration type seawater and sea sand concrete is obtained. According to the invention, the thermally activated muck replacing part of cement is treated by metakaolin and water glass to facilitate formation of Friedel's salt, so that the curing capacity of chloride ions in seawater is improved, and the corrosion influence of free chloride ions on steel is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and in particular relates to a method for preparing carbon-fixing seawater sand concrete mixed with activated slag. Background Art

[0002] Traditional ordinary Portland cement concrete is usually made by mixing river sand, gravel, cement and pure water according to a predetermined mix ratio. At present, the sand and gravel resources in rivers, lakes and reservoirs are scarce and fresh water resources are precious, which has brought huge economic investment and brought many challenges to the environment. In addition, cement production requires a "two grinding and one burning" process, which consumes a lot of energy.

[0003] Seawater and sea sand concrete is subject to adverse conditions such as chloride ions, sulfate ions, magnesium ions, sodium ions and other inorganic salt ions, as well as shells, which accelerate the corrosion of steel bars and the deterioration of concrete, posing a safety hazard to the building structure. In order to avoid steel corrosion, FRP bars are usually developed to replace steel bars to avoid problems caused by chloride ions. At the same time, due to the long-term impact of seawater, the surface of sea sand is smooth, which is easy to be in poor contact with cementitious materials, has large pores, and insufficient bonding force, resulting in lower strength than river sand. In addition, chloride salts are natural early setting agents. Seawater and sea sand concrete has an early initial setting time due to the presence of sulfates and chloride salts in seawater. Sea sand is smoother due to hydraulic action and has a small specific surface area. The contact area between cementitious materials and sea sand is small and has a large air content. Due to its weak carbon fixation ability, it affects the mechanical properties and durability of concrete.

[0004] With the rapid development of urbanization and the shortage of land resources, my country has developed and utilized underground space on a large scale, resulting in a sharp increase in the stock of construction waste, which accounts for nearly 60% of the total construction and demolition waste. Most of the construction waste is transported to landfills, and a large amount of construction waste is piled up and cannot be used, which wastes high transportation costs and causes urban traffic jams, environmental pollution, and safety hazards.

[0005] In response to the country's "dual carbon strategy", replacing cement with appropriate slag while ensuring that there is no significant change in material strength, etc., and realizing the gradual disposal of construction slag has an important role in social development and green environment. Therefore, how to use slag for seawater sand concrete, improve the carbon fixation capacity of seawater sand concrete, and obtain low production cost, high strength, good working performance, and green environmental protection concrete is of great significance to the development of the current building materials industry. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings involved in the preparation process of the above-mentioned seawater and sea sand concrete, and to provide a method for preparing carbon-fixing seawater and sea sand concrete mixed with activated slag. The present invention adopts the following technical solutions: A method for preparing carbon-fixing seawater sand concrete mixed with activated slag, comprising the following steps: S1. Take soil from the project excavation as raw material slag, and dry the taken slag through drying equipment; directly obtain raw material slag from the project excavation, avoiding resource consumption and environmental impact caused by additional mining of new soil, achieving effective reuse of engineering slag, and reducing problems such as land occupation and possible environmental pollution caused by slag accumulation. Drying the slag with drying equipment can remove excess moisture, making the properties of the slag more stable in the subsequent processing process, which is conducive to accurately controlling the mix ratio of concrete, thereby ensuring the stability of concrete quality.

[0007] S2, the slag of step S1 is screened to obtain slag powder, the slag powder is activated by heat treatment and calcination, the heat-activated slag powder is mixed with metakaolin and water glass and stirred to form a heat-activated slag mixture; after screening to obtain slag powder, heat treatment and calcination are performed for activation. This process can change the internal structure of the slag, so that the originally wrapped substances are exposed or new active sites are generated, thereby improving the activity of the slag in concrete and enhancing its synergistic effect on cementitious materials such as cement. Water glass can adjust the alkaline environment of the system, which is conducive to the hydration reaction of minerals in an alkaline environment, thereby improving the strength and durability of concrete. Metakaolin has high activity and can react with water glass and the like to generate a product with gelling properties. After mixing with heat-activated slag, the gelling properties of the mixture can be further improved, the pores caused by the poor contact between sea sand and cementitious materials can be filled, the bonding force can be enhanced, and the mechanical properties of concrete can be improved.

[0008] S3, screening sea sand and mixing it evenly with crushed stone particles, adding cement to mix to obtain a cement-based mixture; screening sea sand and mixing it evenly with crushed stone particles can ensure a reasonable distribution of concrete aggregate particle size, avoid concrete inhomogeneity caused by excessive particle size differences, and improve the working performance of concrete. Specifically, this helps to form a more stable skeleton structure inside the concrete and improve the mechanical properties of concrete such as compression and flexural resistance. Adding cement to mix to obtain a cement-based mixture ensures the uniform distribution of cement between sea sand and crushed stone. Cement can wrap sea sand and crushed stone particles, form a cementitious product during the hydration process, bond the particles together, and further enhance the integrity and strength of the concrete.

[0009] S4. Mix the activated slag soil mixture, cement-based mixture, seawater, admixtures and admixtures and place them in a sealed carbonization box to obtain carbon-fixing seawater sand concrete mixed with activated slag soil. Mix various materials and place them in a sealed carbonization box to obtain carbon-fixing seawater sand concrete mixed with activated slag soil. In a sealed environment, a carbonization reaction will occur inside the concrete, absorbing carbon dioxide from the outside and fixing it in the concrete structure, which helps to reduce the carbon dioxide content in the atmosphere.

[0010] Specifically, the addition of activated slag and the sealed carbonization process work together to not only improve the durability problems of seawater and sea sand concrete, such as steel corrosion and concrete deterioration, which were originally caused by chloride ions, sulfate ions, etc., but also improve the comprehensive performance of concrete, such as strength and workability, making the concrete more green and environmentally friendly while meeting the requirements of building structures.

[0011] Friedel salt is a layered double hydroxide compound with a positively charged main layer and a negatively charged interlayer structure. It can adsorb and fix chloride ions through electrostatic action, hydrogen bonding and van der Waals force. In an environment with a pH greater than 12, Friedel salt can stably exist in an environment containing chloride ions. The aluminum phase provided by the hydration of calcium trialuminate C3A in cement can adsorb chloride ions, thereby generating Friedel salt. During the hydration process, calcium tetraaluminate iron C4AF in cement clinker will hydrate and release aluminum phases, which will combine with chloride ions in the solution to form Friedel salt in a chloride salt environment. Friedel salt can combine and fix chloride ions, thereby reducing the erosion and damage of chloride ions to cement-based materials. The formation of Friedel salt also helps to improve the durability and impermeability of cement-based materials. The aluminum oxide and silicon oxide of the metakaolin of the present invention generate Friedel salt with the clinker calcium trialuminate C3A in cement to achieve the solidification of chloride ions. The chloride ion solidification ability is related to the cement hydration product CSH gel (i.e., hydrated calcium silicate gel) and the Friedel salt content. In cement-based materials, the content of CSH gel generated by hydration is much greater than that of Friedel salt, but the chloride ion curing amount of Friedel salt accounts for 65-75% of the total chloride ion curing amount of cement-based materials, while the chloride ion curing amount of CSH gel accounts for only about 20-25%.

[0012] Furthermore, calculated by mass, the heat-activated slag mixture comprises 100-150 parts, sea sand 500-600 parts, cement 400-600 parts, crushed stone particles 1000-1200 parts, sea water 230-250 parts, admixture 6-10 parts, and admixture 30-60 parts.

[0013] Specifically, the heat-activated slag mixture can effectively utilize the construction slag without excessively affecting the original performance of the concrete. An appropriate amount of heat-activated slag mixture can give full play to its active advantages, fill the pores between sea sand and cementitious materials, and enhance the density of concrete. Its active ingredients can react with cement and other cementitious materials to generate additional cementitious products, enhance the bonding force of concrete, and thus improve the strength of concrete. Specifically, using 100-150 parts of heat-activated slag mixture can not only consume a large amount of construction slag and reduce the cost of building materials, but also reduce carbon emissions through the carbon fixation of slag, which meets environmental protection requirements.

[0014] Specifically, when 80-120 parts of construction waste are used, 30-40 parts of water glass are used, with a modulus of 2.31, a content of 42%, and a Baume degree of 50.

[0015] Water glass can form a stable aluminosilicate structure with better resistance and improve the freeze-thaw resistance of thermally activated slag-soil mixtures. Water glass contains a large amount of active silicon. In the thermally activated slag-soil mixture, these active silicons can react with aluminosilicates in metakaolin to form aluminosilicate gels with a three-dimensional network structure. This gel structure can fill the gaps between slag particles, making the mixture have better gelling properties. Compared with sodium hydroxide, it can not only provide an alkaline environment to promote the activation of minerals, but also directly participate in the polymerization reaction to form more aluminosilicate gels. Sodium hydroxide mainly stimulates activity by destroying and reconstructing the mineral structure. Sodium hydroxide is easy to cause alkali-aggregate reaction, resulting in expansion cracks in concrete or mortar. The presence of water glass helps to strengthen the chemical bonding between mineral particles. During the thermal activation process, the silicon-oxygen tetrahedron in water glass can interact with structural units such as aluminum-oxygen octahedron in slag to form more stable chemical bonds, such as Si-O-Al bonds. The formation of this chemical bond makes the structure of the mixture denser.

[0016] Specifically, the sea sand of the present invention comes from the Pearl River Estuary in South China, and its chemical composition has a chloride ion content of 0.062%, a shell content of 2%-30%, and a mud content of 0.75%. By particle size screening, the fineness modulus of sea sand is controlled to be 2.2-2.8. Sea sand plays a filling and supporting role in concrete, and cooperates with gravel to effectively resist external forces. The particle shape and size of sea sand can affect the working performance of concrete. Within this range, it can be ensured that the concrete has good fluidity and is convenient for construction operations. The amount of 500-600 parts of sea sand can make full use of local sea sand resources while meeting the needs of concrete production, reduce long-distance transportation costs and environmental impacts, and reduce dependence on scarce resources such as river sand.

[0017] Specifically, the cement type used is P·O42.5, and the density is controlled at 3100-3200kg / m 3 ,400-600 parts of cement paste can ensure that there is enough cement paste to wrap the sea sand and gravel particles. While controlling the production cost, cement can generate a large amount of hydration products during the hydration process, such as calcium silicate gel, which binds the aggregates together, provides sufficient strength and stability for the concrete, and can ensure that the concrete reaches the required mechanical properties such as compression and flexural strength.

[0018] Specifically, crushed stone particles form the skeleton structure of concrete, which can improve the overall compressive strength and durability. Compared with sea sand, crushed stone particles have a larger particle size, which can improve the impact resistance and wear resistance of concrete. Crushed stone particles can also improve the working performance of concrete. It can adjust the workability of concrete, prevent segregation of concrete during construction, and ensure the uniformity of the quality of concrete during pouring, vibrating, etc.

[0019] Specifically, the seawater of the present invention comes from Zhanjiang Port in South China, and its seawater components include 2198 mg / L sulfate, 800 mg / L magnesium ion, and an average pH value of 7.7, which is alkaline. Using seawater instead of fresh water for concrete mixing can alleviate the shortage of fresh water resources.

[0020] Specifically, adding admixtures can help concrete overcome performance defects caused by sea sand, seawater, etc., enhance the durability and stability of concrete, and help further improve the overall quality and service life of concrete. Specifically, the addition of admixtures can refine the microstructure of concrete, improve density and corrosion resistance. Admixtures work synergistically with cement to improve long-term performance.

[0021] Furthermore, the slag in step S1 is dried at 100-110°C for 24 hours, and the calcination temperature in step S2 is 700-750°C. In step S1, the slag is dried at 100-110°C for 24 hours. Under this temperature and time condition, it can be ensured that the free water and part of the bound water in the slag are fully removed. During the screening process, the thoroughly dried slag will not cause problems such as adhesion and agglomeration due to the presence of water, which will affect the screening accuracy, which is conducive to ensuring the quality uniformity of the slag powder. This mild and continuous drying condition will not damage the mineral composition and microstructure of the slag. The stable physical and chemical properties help to accurately control the reaction and performance changes of the slag in subsequent screening, calcination activation and other processes, thereby ensuring the quality stability of the final concrete.

[0022] Specifically, the calcination temperature in step S2 is 700-750°C. This calcination temperature range can effectively cause certain mineral components in the slag to undergo crystal transformation or decomposition reactions, thereby exposing more active points. The aluminosilicate minerals in the slag undergo dehydration, decomposition and other reactions to produce active amorphous phase substances, which greatly improve the activity of the slag, so that it can better synergize with cement and other cementitious materials in concrete. When calcined at 700-750°C, the internal structure of the slag is optimized and the pore structure is more reasonable. On the one hand, some unstable structural parts are removed, and on the other hand, the new structure formed is conducive to improving the adhesion between the slag and other materials, thereby improving the overall strength and durability of the concrete. The calcination temperature range of 700-750°C avoids excessive damage to the slag structure due to excessively high temperatures. If the temperature is too high, some components in the slag will be over-melted or irreversible chemical changes will occur, resulting in reduced activity or the production of harmful substances.

[0023] Furthermore, the admixture includes one or more of silica fume, sepiolite, and modified slag powder.

[0024] Specifically, silica fume has a very small particle size and can be evenly dispersed in concrete, acting as a bridge between cement particles, making the microstructure of concrete more compact and uniform, further improving the overall performance of concrete. Silica fume can improve the rheological properties of concrete. To a certain extent, it increases the cohesiveness of concrete, reduces the segregation and bleeding of concrete during construction, makes the working performance of concrete better, and facilitates construction operations.

[0025] The main component of silica fume is amorphous silicon dioxide, which can react with calcium hydroxide, a cement hydration product, to generate more hydrated calcium silicate gel. These gels fill the pores in the concrete, greatly improving the density of the concrete, thereby significantly improving the compressive and flexural strength of the concrete. Compared with concrete without silica fume, its early strength will be better. Since silica fume fills the pores inside the concrete, it reduces the channels for water and chloride ions and sulfate ions to enter the concrete, improves the concrete's impermeability, frost resistance and chemical corrosion resistance, thereby extending the service life of the concrete structure. In seawater sand concrete, it can absorb chloride ions and magnesium ions in seawater, reducing the erosion of these ions on steel bars and cementitious materials in the concrete.

[0026] Specifically, the addition of sepiolite can increase the fluidity and water retention of concrete. Its fibrous structure can play a role of lubrication and support in the concrete mixture, making the concrete easier to operate during mixing and pouring, while reducing the occurrence of bleeding and segregation. The fibrous structure of sepiolite can form a three-dimensional network structure inside the concrete, enhancing the integrity and stability of the concrete. This structure can effectively resist the expansion of cracks generated by concrete when subjected to external forces, and improve the crack resistance of concrete. Sepiolite itself has certain heat resistance. Sepiolite can protect the concrete structure to a certain extent, slow down the destruction rate of concrete, and improve the heat resistance limit of concrete.

[0027] Specifically, the activity of the modified slag powder is improved, and it can react quickly with calcium hydroxide in cement. More cementitious substances are generated to fill the pores inside the concrete, improving the density and strength of the concrete. It works synergistically with cementitious materials such as cement to optimize the performance of concrete. Using modified slag powder as an admixture can replace part of the cement to a certain extent, reduce the production cost of concrete, and at the same time realize the resource utilization of industrial waste residues and reduce pollution to the environment. Modified slag powder can improve the resistance of concrete to chemical erosion. In seawater and sea sand concrete, it can resist the erosion of sulfates, chlorides, etc. in seawater on concrete, reduce the risk of expansion and cracking of concrete, and improve the durability of concrete in harsh environments.

[0028] Preparation method of modified slag powder: M1. Mix S95 grade slag powder and ultrafine steel slag powder evenly, and grind the slag by a ball mill; Specifically, by weight, 70 parts of S95 grade slag powder and 20 parts of ultrafine steel slag powder can be ground by a ball mill for 2-4 hours, which can significantly increase the specific surface area of ​​the slag powder and make the particles finer and more uniform. This not only increases the contact opportunity between the slag powder and the cement hydration product, but also speeds up the reaction rate and enhances its reactivity. Finer particles enable the material to be better dispersed when mixed with water, reduce agglomeration, and improve fluidity. Ultrafine steel slag powder has active ingredients such as calcium oxide, silicon dioxide, and aluminum oxide. The mixing of ultrafine steel slag powder and slag powder can achieve complementary performance. The introduction of ultrafine steel slag powder further refines the particle size distribution of slag powder, which helps to form a denser microstructure in concrete, reduce porosity, and improve impermeability and density.

[0029] M2. Evenly mix the ground slag powder and hemihydrate gypsum; add triethanolamine and grind the slag in a ball mill for 4-8 hours. Calculated by mass, the hemihydrate gypsum is 10 parts and the triethanolamine is 0.5 parts. The grinding specific surface area is 520-550m² / kg. In an alkaline environment, hemihydrate gypsum can react with aluminum oxide and iron oxide in the slag to form a stable hydration product of tobermorite, thereby enhancing the gelling properties of the slag powder, improving the compressive and flexural strength of the concrete, and also improving the durability of the material, and enhancing the impermeability and resistance to chemical erosion.

[0030] In addition, hemihydrate gypsum will quickly hydrate to dihydrate gypsum after contact with water. In this process, gypsum can react with calcium aluminate in slag powder to form ettringite. ettringite is a kind of expansive crystal that can fill the pores in concrete, making the concrete more dense, thereby improving the strength and impermeability of concrete.

[0031] Specifically, triethanolamine can be adsorbed on the surface of slag powder particles to promote the hydration reaction of slag powder. The hydroxyl groups in the triethanolamine molecules can interact with the active ions in the slag to form hydrogen bonds, etc., to reduce the activation energy of the hydration reaction. Relative to ordinary slag powder, the hydration reaction can have higher strength in the early stage, and also has a positive impact on the later strength development of the material. As a grinding aid, triethanolamine can improve the particle shape and distribution of slag powder, reduce particle agglomeration, and improve its fluidity and workability. In addition, triethanolamine also has a certain water-reducing effect, can reduce the amount of water used in concrete, and improve the compactness and durability of concrete.

[0032] Furthermore, the admixture includes a retarder, an air entraining agent, and a water reducer. The retarder includes one or more of calcium ethylenediaminetetramethylenephosphonate, sodium carboxymethyl cellulose, sodium gluconate, and borax. The air entraining agent includes one or more of triterpenoid saponins, modified rosin acid soaps, and fatty alcohol polyoxyethylene ethers. The water reducer includes one or more of calcium lignin sulfonate, naphthalenesulfonic acid formaldehyde condensate, and a polycarboxylic acid-based water reducer whose main chain is a copolymer of methacrylic acid and methyl acrylate and whose side chain is a polyoxyethylene group.

[0033] Specifically, the main function of the retarder is to delay the setting time of concrete, thereby providing a longer construction window, facilitating construction operations and adjustments. The retarder helps to maintain the good fluidity and plasticity of concrete, reduce bleeding and segregation, and improve the construction quality. The retarder can improve the impermeability, crack resistance and durability of concrete by improving the internal structure of concrete and reducing shrinkage cracks. Specifically, the dosage range of the retarder of the present invention can prolong the setting time of concrete, and increase the overall mechanical strength by adding other components, so that the early strength of the concrete of the present invention is not much different from the early strength of ordinary concrete without the application of the retarder, and maintains a certain strength when the setting time is delayed. The present invention has a more convenient construction time relative to ordinary concrete.

[0034] Specifically, since the chloride salts in seawater are natural early setting agents, they will cause the initial setting time of concrete to be advanced. Calcium ethylenediaminetetramethylenephosphonate can adjust the hydration process of cement so that the setting time of concrete meets the construction requirements, help maintain the good fluidity and pumpability of concrete, and facilitate construction operations, such as having enough time for the mixing, transportation, pouring and vibration of concrete. It can react with calcium ions and other components in cement to inhibit the rapid hydration of cement to a certain extent, thereby reducing the temperature stress and shrinkage cracks caused by rapid hydration inside the concrete. This helps to improve the crack resistance of concrete and enhance the durability of concrete structures. Specifically, sodium carboxymethyl cellulose can be adsorbed on the surface of cement particles to form a protective film, which hinders the contact between cement particles and water, thereby delaying the hydration reaction of cement and playing a retarding role. At the same time, it can absorb and retain moisture in concrete, reduce the evaporation of water in concrete during transportation and construction, and prevent the problem of excessive slump loss due to water loss in concrete. Sodium carboxymethyl cellulose can enhance the cohesiveness of concrete, prevent the segregation of sea sand due to its smooth surface, ensure the uniformity and stability of concrete during mixing and construction, and improve the quality of concrete. By improving the cohesiveness and water retention of concrete, sodium carboxymethyl cellulose helps to reduce the pores and microcracks inside concrete. This is very beneficial for improving the impermeability of concrete, can effectively prevent the intrusion of corrosive media such as seawater, and enhance the durability of concrete in seawater environments.

[0035] Specifically, sodium gluconate can accurately adjust the setting time of concrete. It can produce a significant retarding effect at a lower dosage. Sodium gluconate can improve the working performance of concrete and make the concrete have better fluidity and plasticity. During the hydration process of concrete, it can also participate in some chemical reactions, promote the uniform distribution of cement hydration products, and help improve the strength of concrete. At the same time, it can reduce the internal defects of concrete caused by premature setting, thereby improving the overall quality and durability of concrete.

[0036] Specifically, borax can react with calcium hydroxide and other ingredients in cement to form a relatively stable compound, thereby delaying the hydration reaction of cement. In seawater and sea sand concrete, this is very effective in overcoming the problem of premature initial setting time caused by chloride salts in seawater, and can extend the operable time of concrete and ensure the smooth progress of concrete construction. Borax can form a protective film inside the concrete, which can resist the erosion of harmful chemicals such as sulfates and chloride ions in seawater. In the early strength development stage of concrete, borax can make cement hydration products more evenly distributed, improve the stability of the early strength of concrete, and avoid damage to the concrete structure due to premature stress.

[0037] Specifically, when used alone or in combination, air-entraining agent components can play a positive role in improving concrete workability, frost resistance, durability, and other aspects, and comprehensively improve the comprehensive performance of concrete. Air-entraining agents help improve the construction quality of concrete, reduce construction problems caused by poor concrete performance such as segregation, bleeding, unevenness, etc., and ensure the overall quality of concrete structures.

[0038] Specifically, triterpenoid saponins can produce a large number of tiny bubbles in concrete as air entraining agents. These bubbles are evenly distributed inside the concrete and play a lubricating role, thereby effectively improving the workability of concrete. In seawater and sea sand concrete, this good fluidity helps to overcome the problem of poor workability caused by the smooth surface of sea sand, making concrete easier to mix, transport and pour. In a cold environment, when the water in the concrete freezes and expands in volume, the bubbles can buffer this expansion force, prevent the concrete from cracking due to excessive internal stress, thereby significantly improving the frost resistance of the concrete and extending the service life of the concrete structure. The bubbles introduced by triterpenoid saponins can cut off the capillary channels inside the concrete and reduce the permeability of the concrete. In a seawater environment, this helps to prevent the intrusion of harmful ions such as chloride ions and sulfate ions in seawater, reduce steel corrosion and chemical erosion of concrete, thereby enhancing the durability of concrete.

[0039] Specifically, modified rosin acid soap can reduce the surface tension of concrete, making it easier for concrete to wrap air and form bubbles during the mixing process. The bubbles are evenly distributed in the concrete and are not easy to burst, thereby improving the working performance of the concrete, such as fluidity and cohesion, making it easier for construction workers to operate and improving construction efficiency. The bubbles introduced can increase the elasticity of concrete to a certain extent. When concrete is subjected to external loads, the concrete around the bubbles can produce a certain elastic deformation, thereby absorbing and dispersing the load energy and reducing the risk of damage to the concrete structure. Stable bubbles can reduce the interconnected pores inside the concrete, reduce the diffusion rate of harmful ions in the concrete, and prevent the steel bars in the concrete from being corroded prematurely.

[0040] Preparation method of modified rosin acid soap: N1. Add rosin acid, anhydrous zinc chloride and sulfuric acid into a reaction vessel, raise the temperature to 110-120° C., and stir for 2-5 hours to obtain a dimerized rosin acid solution; Specifically, the amount of anhydrous zinc chloride is 0.5%-1% of the mass of rosin acid, the amount of sulfuric acid is 0.3%-0.8% of the mass of rosin acid, and the stirring speed is 150-200 rpm to promote the dimerization reaction of rosin acid.

[0041] N2, gradually add sodium hydroxide, control the saponification reaction temperature at 85-95°C, stir the reaction time for 2-3 hours, and obtain a saponification reaction product; the aqueous solution of sodium hydroxide reacts with dimerized rosin acid to generate dimerized rosin acid soap, the molar ratio of dimerized rosin to sodium hydroxide is 1:2-1:2.5, and the stirring speed is 200-300rpm.

[0042] N3. Separate, wash, dry and crush the saponification reactants to obtain modified rosin acid soap. Separate the dimerized rosin acid soap from the unreacted alkali solution and impurities by centrifugal separation, and then wash the dimerized rosin acid soap with hot water at a washing temperature of 70-80°C for 2-3 times to remove the residual alkali solution and impurities. Dry the washed dimerized rosin acid soap in a vacuum drying oven at 60-70°C for 4-6 hours to reduce the water content of the product to less than 3%. The dried product can be crushed by a pulverizer and sieved to obtain a dimerized rosin acid soap product with a sieve of 80-100 mesh.

[0043] Specifically, fatty alcohol polyoxyethylene ether can produce bubbles of uniform size. The polyoxyethylene ether segments in its molecular structure can form hydrogen bonds with water molecules, making the bubbles more stable in concrete, which helps to improve the fluidity and cohesion of concrete. The bubbles can disperse the stress inside the concrete. When the concrete is subjected to external forces or shrinks due to factors such as temperature changes, the bubbles can act as a buffer to reduce the generation of cracks. The bubbles produced by fatty alcohol polyoxyethylene ether can optimize the internal structure of concrete to a certain extent, making the concrete more compact and reducing performance defects caused by factors such as uneven aggregate accumulation.

[0044] Specifically, water reducers can improve the compression, tension, impermeability, and frost resistance of concrete by reducing water consumption and optimizing the internal structure of concrete, thereby extending the service life of concrete structures. In addition, water reducers can reduce the amount of cement used, reduce production costs, and reduce energy consumption and emissions caused by cement production. Furthermore, water reducers can increase the fluidity and pumpability of concrete, facilitate construction operations, and improve construction efficiency and quality.

[0045] Specifically, calcium lignin sulfonate can be adsorbed on the surface of cement particles, making the cement particles charged, thereby generating electrostatic repulsion. This repulsion can make the cement particles disperse more evenly in the water, release the water wrapped by the cement particles, effectively reduce the water consumption of concrete, and help improve the strength and durability of concrete. In seawater and sea sand concrete, calcium lignin sulfonate can reduce the water-cement ratio while maintaining the slump of concrete. This improves the fluidity of concrete, while enhancing the cohesiveness and water retention of concrete, effectively avoiding the segregation phenomenon that is easy to occur in sea sand due to its smooth surface, and facilitating the construction operation of concrete.

[0046] Specifically, naphthalenesulfonic acid formaldehyde condensate has a strong dispersing ability on cement particles and can significantly reduce the water consumption of concrete. At a lower dosage, it can produce a significant water-reducing effect, greatly reducing the water-cement ratio of concrete, thereby improving the strength of concrete. In seawater and sea sand concrete, high strength can better resist seawater erosion and other external forces. Naphthalenesulfonic acid formaldehyde condensate regulates the setting time of concrete to a certain extent. It can slow down the early hydration rate of cement and avoid the construction difficulties caused by too fast setting of concrete. Especially in concrete containing seawater, it helps to overcome the early setting problem caused by chloride salts in seawater and make the working performance of concrete more stable. By reducing the water-cement ratio, naphthalenesulfonic acid formaldehyde condensate can reduce the porosity inside the concrete and make the concrete more compact. This helps to improve the impermeability and chemical erosion resistance of concrete, prevent chloride ions and sulfate ions in seawater from invading the interior of concrete, thereby extending the service life of seawater and sea sand concrete structures.

[0047] Specifically, polycarboxylic acid-based water reducers have excellent water-reducing properties, which can significantly improve the slump and expansion of concrete, while reducing the amount of water and cement. The polyoxyethylene groups in its side chains can provide a steric hindrance effect, ensuring good dispersion of cement particles even in complex seawater environments. At the same time, it can also enhance the slump retention capacity of concrete, allowing the concrete to maintain good fluidity for a long time, which is convenient for transportation and pouring during construction. The synergistic effect of the main chain and the side chain gives it excellent dispersion properties for cement particles. It can achieve efficient water reduction effects at extremely low dosages and maintain the dispersion stability of cement particles. It can accurately control the amount of water, optimize the mix ratio of concrete, and obtain higher strength and better working performance.

[0048] Specifically, polycarboxylate-based water reducers can improve the comprehensive performance of seawater and sea sand concrete. They can reduce the shrinkage of concrete, reduce the occurrence of cracks, and improve the crack resistance of concrete. In addition, by reducing porosity, they can also enhance the impermeability and chemical corrosion resistance of concrete, significantly improving the durability and long-term stability of concrete in seawater environments.

[0049] Preparation method of polycarboxylic acid water reducer with main chain composed of methacrylic acid and methyl acrylate copolymer and side chain composed of polyoxyethylene: P1. At 60-80°C, methacrylic acid, methyl acrylate, ammonium persulfate and thioglycolic acid are added dropwise to the methoxy polyethylene glycol methacrylate solution to form a mixed solution; P2. Keep the reaction at 60-80°C for 2-4 hours. After the reaction is completed, cool the reaction solution to room temperature and adjust the pH value with water glass solution to obtain a polycarboxylic acid-based water reducer product.

[0050] Specifically, the molecular weight of methoxy polyethylene glycol methacrylate is 1000-5000, and its purity is greater than 95%. Methoxy polyethylene glycol methacrylate is stirred evenly with water to obtain a solution with a mass fraction of 30%-50%. Under nitrogen protection, the methoxy polyethylene glycol methacrylate solution is added to a flask and placed in a constant temperature water bath at 60-80°C. The molar ratio of methacrylic acid to methyl acrylate is 1:1-3:1, the amount of ammonium persulfate is 1%-5% of the total mass of methacrylic acid and methyl acrylate, and the amount of thioglycolic acid is 0.5%-2% of the total mass of methacrylic acid and methyl acrylate. After the reaction is completed, the reaction solution is cooled to room temperature, and the pH value is adjusted to 6-7 with a water glass solution with a mass fraction of 20%-30%.

[0051] Further, in step S4, the sealed carbonization box is connected to the carbon dioxide tank, and stirring is performed at a temperature of 50-70° C. and a carbonization pressure of 0.4 MPa for 4-5 minutes.

[0052] Specifically, a temperature of 50-70°C helps to accelerate the reaction rate of carbon dioxide with minerals in the activated slag and cement hydration products, thereby improving the carbonization efficiency. Higher temperatures provide more energy for the reaction, allowing carbon dioxide to react more effectively with substances such as calcium hydroxide to generate carbonization products such as calcium carbonate, thereby enhancing the mechanical properties of concrete. At this temperature, the moisture distribution in the concrete is more reasonable, which helps the newly generated carbonization products to better fill the pores. At the same time, the temperature increase will not be too high to cause excessive evaporation of moisture in the concrete or damage to the material properties, ensuring the stability of the concrete during the carbonization process, which is beneficial to improving the strength and density of the concrete.

[0053] Specifically, a carbonization pressure of 0.4 MPa can make it easier for carbon dioxide to penetrate into the concrete. Higher pressure can overcome the resistance of the pore structure inside the concrete to the diffusion of carbon dioxide, allowing more carbon dioxide to contact and react with the active ingredients in the concrete, further increasing the carbonization depth, and helping carbon dioxide to be more evenly distributed inside the concrete, avoiding excessive or insufficient local carbonization. The carbonization reaction under pressure conditions can make the internal structure of the concrete denser, improving its impermeability and durability.

[0054] Specifically, a stirring time of 4-5 minutes can ensure sufficient mixing and contact between the various components of the concrete and the carbon dioxide gas, improving the uniformity and effectiveness of the reaction. The stirring process helps to form a uniform and fine bubble network, which not only participates in the carbonization reaction, but also improves the workability and durability of the concrete. During the stirring process, the newly generated carbonized products can better fill the pores, interact with other components, and enhance the integrity of the concrete. This helps to improve the mechanical properties and durability of the concrete, making it more stable and reliable in subsequent use, and better able to resist problems such as seawater erosion and steel corrosion.

[0055] Furthermore, the chloride ion solidification amount of the activated slag mixture accounts for 65-75% of the total chloride ion solidification amount in the carbon-fixing seawater and sea sand concrete mixed with activated slag.

[0056] In some embodiments of the present invention, the aluminum oxide and silicon oxide of metakaolin react with the clinker C3A in cement to generate Friedel salt to achieve the solidification of chloride ions. When the amount of metakaolin reaches 20%, the solidification effect is optimal. The chloride ion solidification ability is related to the content of CSH gel and Friedel salt, which are the products of cement hydration. In the cement-based material of the present invention, the content of CSH gel generated by hydration is much greater than that of Friedel salt, but the chloride ion solidification amount of Friedel salt accounts for 70% of the total chloride ion solidification amount of the cement-based material, while the chloride ion solidification amount of CSH gel accounts for only about 25%.

[0057] Specifically, chloride ions in seawater react with some components in concrete to produce expansion stress, causing cracks in the concrete. The activated slag mixture effectively alleviates this chemical erosion by solidifying a large amount of chloride ions, enabling concrete to better resist chemical corrosion in complex environments such as seawater and maintain structural integrity, thereby reducing the risk of steel corrosion and extending the service life of concrete structures. Reducing chloride ion erosion not only protects the steel bars, but also avoids cracking and spalling of concrete caused by corrosion, thereby improving the stability and bearing capacity of the structure.

[0058] Furthermore, the thermally activated slag powder includes silicon dioxide, aluminum oxide, calcium oxide and magnesium oxide.

[0059] Specifically, in some embodiments, the heat-activated slag powder has oxides calculated by mass percentage as follows: 55.25% silicon dioxide, 35.3% aluminum oxide, 0.925% calcium oxide, 0.628% magnesium oxide, and the rest are other oxides.

[0060] Specifically, in the concrete system, silicon dioxide reacts with calcium hydroxide, a cement hydration product. This reaction will generate more calcium silicate gel, which can fill the pores between sea sand and cementitious materials in seawater and sea sand concrete, making the concrete more compact, thereby improving the strength and impermeability of the concrete. The generated calcium silicate gel can effectively prevent the intrusion of chloride ions and sulfate ions in seawater, and silicon dioxide can adjust the rheological properties of concrete. It can make concrete have better cohesion, reduce the segregation phenomenon caused by the smooth surface of sea sand, ensure the uniformity of concrete during mixing, transportation and pouring, and thus improve the working performance of concrete.

[0061] Specifically, alumina can participate in complex gelling reactions in concrete. It can react with other components in cement and other admixtures to form aluminate phases, which can further react with calcium hydroxide to generate products with gelling properties. This reaction helps to enhance the integrity of concrete and improve the early strength of concrete. Alumina can form stable chemical bonds inside concrete and enhance the bonding between mineral phases inside concrete. Thereby improving the corrosion resistance of concrete. Due to the stabilizing effect of alumina on the internal structure of concrete, it can indirectly improve the working performance of concrete. It can keep concrete in good fluidity and plasticity for a long time, which is convenient for construction operations. At the same time, the stable structure also helps to improve the durability of concrete.

[0062] Specifically, calcium oxide can directly participate in the hydration reaction of cement in the concrete system. It reacts with water to form calcium hydroxide, which can react with other active ingredients such as silicon dioxide, aluminum oxide, etc. to form cementitious products, thereby providing strength for concrete. The presence of calcium oxide keeps a certain alkaline environment inside the concrete. In seawater and sea sand concrete, steel bars are easily corroded by chloride ions, etc., and the alkaline environment can form a passivation film on the surface of the steel bars, preventing harmful substances such as chloride ions from directly contacting the steel bars, thereby preventing steel bars from rusting and improving the durability of the concrete structure. An appropriate amount of calcium oxide can improve the workability of concrete. It can make concrete easier to mix evenly during the mixing process, improve the fluidity of concrete, and to a certain extent reduce the bleeding of concrete, ensure the uniformity of concrete quality, and facilitate the construction operation of concrete.

[0063] Specifically, magnesium oxide can play a role in compensating shrinkage in concrete. During the hardening process of concrete, shrinkage will occur due to the evaporation of water and chemical reactions. Magnesium oxide reacts with water to form magnesium hydroxide, and its volume expansion can compensate for the shrinkage of concrete, thereby reducing the shrinkage stress inside the concrete, avoiding cracks in the concrete due to shrinkage, and preventing seawater from invading the interior of the concrete through cracks. Magnesium hydroxide is an alkaline substance, which can react with acidic substances in seawater, such as sulfate ions, to neutralize and reduce the erosion of concrete by acidic substances. At the same time, the presence of magnesium oxide can also increase the alkalinity inside the concrete, enhance the protective effect on steel bars, reduce the risk of steel bar corrosion, and improve the durability of concrete in seawater environments. Magnesium oxide can improve the working performance of concrete. It can make the concrete smoother during mixing and improve the fluidity and plasticity of concrete. From a microstructural point of view, magnesium oxide can refine the pores in the concrete and make the microstructure of the concrete denser, thereby improving the strength and impermeability of the concrete. Furthermore, the ratio of heat-activated slag: metakaolin: water glass in the heat-activated slag mixture is 1:0.2:0.25-0.5.

[0064] Specifically, metakaolin has high volcanic ash activity and can interact with active components in thermally activated slag, such as silica and alumina. In the concrete system, this combination can produce a synergistic gelling effect, generating more gelling products, such as calcium silicate gel and calcium aluminate gel. These gelling products can fill the pores inside the concrete, especially the pores between sea sand and the cementitious material, making the concrete more compact, thereby effectively improving the strength and impermeability of the concrete.

[0065] Specifically, compared with ordinary heat-activated slag mixed only with alkaline substances, the addition of kaolin can improve the early strength of concrete, reduce the shrinkage deformation of concrete by optimizing the hydration reaction, and improve the overall stability of concrete. By optimizing the hydration products, the concrete's impermeability, frost resistance and chemical corrosion resistance can be improved, thereby enhancing the durability of concrete. Using these industrial waste residues as raw materials for concrete can reduce the production cost of concrete and improve economic benefits.

[0066] Specifically, the heat-activated slag and water glass are mixed in a ratio of 1:0.25-0.5. As an activator, water glass can promote the dissolution of silicon-aluminum minerals in the slag, release more active silica and alumina, thereby enhancing the activity of the heat-activated slag, allowing it to better participate in the gelling reaction and improve the strength of the concrete. In seawater and sea sand concrete, the alkaline environment can also form a passivation film on the surface of the steel bars, protecting the steel bars from corrosion by harmful ions such as chloride ions, and improving the durability of the concrete structure. At the same time, an appropriate amount of water glass can control the reaction speed and avoid unstable concrete performance due to too fast a reaction.

[0067] Furthermore, the crushed stone particles include basalt and granite, with a particle size of 5-25 mm and an apparent density of 2600-2800 kg / m 3 .

[0068] Specifically, basalt and granite have high compressive strength and wear resistance. When used as crushed stone particles, they can significantly improve the overall strength and durability of concrete. These rocks are highly resistant to weathering and can resist erosion in the natural environment, thereby extending the service life of concrete structures. The crushed stone particle size ranges from 5-25mm, and this particle size distribution is conducive to forming a compact and uniform concrete structure. Smaller particle sizes can fill the gaps between larger particles, improving the density of concrete.

[0069] At the same time, this particle size range also facilitates the mixing, transportation and pouring of concrete, ensuring smooth construction. The apparent density is in the range of 2600-2800kg / m³, indicating that the crushed stone particles have moderate quality and compactness. This helps to form a stable skeleton structure in the concrete, improving the bearing capacity and compressive strength of the concrete. In addition, this apparent density also helps to reduce the deadweight of the concrete.

[0070] Optionally, in some embodiments, the present invention takes building waste soil and removes water at high temperature, passes through a graded sieve, grinds the powder, and then heat-activates and calcines at 700-750°C to activate the reaction activity. Then, a water glass solution is mixed with metakaolin to dissolve Si oxides, so as to react with cement clinker C3A to generate Friedel salt to achieve the solidification of chloride ions. This is determined by the fact that the chloride ion solidification capacity is related to the content of CSH gel and Friedel salt, a cement hydration product. The content of CSH gel generated by hydration is much greater than that of Friedel salt, but the chloride ion solidification amount of Friedel salt accounts for 70% of the total chloride ion solidification amount of cement-based materials, while the chloride ion solidification amount of CSH gel accounts for only about 25%.

[0071] Take sea sand and screen it to remove the shells. Then control the particle size and gradation by screening, mix it evenly with crushed stone, and then add ordinary Portland cement P·O42.5 to mix.

[0072] Finally, the treated metakaolin, water glass, slag, air entraining agent, retarder, water reducing agent, seawater, sea sand, cement, crushed stone particles, admixtures, etc. are mixed through various steps, stirred and placed in a sealed carbonization box. The retarder mainly delays the initial setting time, and the air entraining agent dissolves large bubbles into dispersed small bubbles under the condition of unchanged strength. The admixture is used to improve the density and bite force between the cementitious material and the aggregate. Before use, the sealed carbonization box is first exhausted with a vacuum pump and connected to the carbon dioxide tank. The temperature is controlled at 60-70℃ and the carbonization pressure is 0.4MPa to achieve carbonization while stirring. The stirring time is 4-5min, so that the carbon dioxide gas is filled in the dispersed small bubbles in the seawater and sea sand concrete. The stirred seawater and sea sand concrete is injected into the mold for standard maintenance.

[0073] Compared with the prior art, the present invention has the following advantages: 1. The present invention replaces part of the thermally activated slag of cement, and after being treated with metakaolin and water glass, more silicon oxides are dissolved, which is conducive to the formation of Friedel salt, thereby improving the solidification ability of chloride ions in seawater and reducing the corrosion effect of free chloride ions on steel; 2. The present invention makes reasonable use of seawater and sea sand concrete, which is beneficial to saving freshwater resources and the ecological environment, and achieves better durability of seawater and sea sand concrete by controlling the content of free chloride ions; 3. The present invention targets the common large pores in seawater and sea sand, adopts admixtures and mineral admixtures to improve the chemical bonding between materials, optimizes the large pores into small pores, and combines driven carbonization to further improve the carbon fixation capacity. DETAILED DESCRIPTION

[0074] In order to make those skilled in the art more clearly understand the technical solution of the present invention, the following examples are listed for illustration. Unless otherwise specified, the raw materials, reagents or devices used in the following embodiments can be obtained from conventional commercial channels or can be obtained by existing known methods.

[0075] The present invention will be further described below in conjunction with specific embodiments: A method for preparing carbon-fixing seawater sand concrete mixed with activated slag, comprising the following steps: S1. Take soil from the project excavation as raw material slag, and dry the taken slag by drying equipment; the slag in step S1 is dried at 100-110°C for 24 hours continuously; S2, the slag in step S1 is screened to obtain slag powder, the slag powder is activated by heat treatment and calcination, and the heat-activated slag powder is mixed with metakaolin and water glass and stirred to form a heat-activated slag mixture; the calcination temperature in step S2 is 700-750°C; the heat-activated slag powder includes silicon dioxide, aluminum oxide, calcium oxide, and magnesium oxide; the heat-activated slag: metakaolin: water glass in the heat-activated slag mixture is 1:0.2:0.25-0.5; S3, sieve the sea sand and mix it evenly with the crushed stone particles, add cement and mix to obtain a cement-based mixture; the crushed stone particles include basalt and granite, the crushed stone particles have a particle size of 5-25mm, continuous grading, and an apparent density of 2600-2800kg / m 3； S4, mixing the activated slag mixture, cement-based mixture, seawater, admixtures and admixtures in a sealed carbonization box to obtain carbon-fixing seawater and sea sand concrete mixed with activated slag; the admixtures include one or more of silica fume, sepiolite and modified slag powder; The following materials are used in the following embodiments, specifically: admixtures include retarders, air entraining agents, and water reducers, the retarder includes one or more of calcium ethylenediaminetetramethylenephosphonate, sodium carboxymethylcellulose, sodium gluconate, and borax, the air entraining agent includes one or more of triterpenoid saponins, modified rosin acid soaps, and fatty alcohol polyoxyethylene ethers, the fatty alcohol polyoxyethylene ether adopts BASF's Disponil A 3065 non-ionic linear fatty alcohol polyoxyethylene ether mixture, the water reducer includes one or more of calcium lignin sulfonate, naphthalenesulfonic acid formaldehyde condensate, and a polycarboxylic acid water reducer with a main chain composed of a copolymer of methacrylic acid and methyl acrylate and a side chain of polyoxyethylene; the naphthalenesulfonic acid formaldehyde condensate adopts Shuer's whshuer dispersant CNF.

[0076] In step S4, the sealed carbonization box is connected to the carbon dioxide tank, and stirring is performed at a temperature of 50-70° C. and a carbonization pressure of 0.4 MPa for 4-5 minutes.

[0077] The seawater from Zhanjiang Port in South China is used. Its seawater composition includes 2198mg / L sulfate, 800mg / L magnesium, and an average pH value of 7.7, which is alkaline.

[0078] The sea sand from the Pearl River Estuary in South China is used. Its chemical composition includes 0.062% chloride ion, 2%-30% shell content, and 0.75% mud content. Through particle size screening, the fineness modulus of the sea sand is controlled to be 2.2-2.8.

[0079] The cement model is P·O42.5, and the density is controlled at 3100-3200kg / m 3 .

[0080] Calculated by mass, the heat-activated slag mixture includes 100-150 parts, sea sand 500-600 parts, cement 400-600 parts, crushed stone particles 1000-1200 parts, sea water 230-250 parts, admixture 6-10 parts, and admixture 30-60 parts.

[0081] The chloride ion solidification capacity of the activated slag mixture accounts for 65-75% of the total chloride ion solidification capacity of the carbon-fixing seawater sand concrete mixed with activated slag.

[0082] Preparation method of modified slag powder: M1. Mix the S95 grade slag powder and the ultrafine steel slag powder evenly, and grind the slag by a ball mill for 2 hours; Calculated by mass, there are 70 parts of S95 grade slag powder and 20 parts of ultrafine steel slag powder.

[0083] M2. Mix the ground slag powder and hemihydrate gypsum evenly; add triethanolamine and grind the slag in a ball mill for 4 hours. The grinding specific surface area is 520m² / kg.

[0084] Preparation method of modified rosin acid soap: N1. Add rosin acid, anhydrous zinc chloride and sulfuric acid into a reaction vessel, raise the temperature to 110° C., and stir for 2 hours to obtain a dimerized rosin acid solution; The amount of anhydrous zinc chloride used is 1% of the mass of rosin acid, the amount of sulfuric acid used is 0.5% of the mass of rosin acid, and the stirring speed is 150 rpm.

[0085] N2, gradually add sodium hydroxide, control the saponification reaction temperature at 85°C, stir the reaction time for 2 hours, and obtain a saponification reaction product; the aqueous solution of sodium hydroxide reacts with dimerized rosin acid to generate dimerized rosin acid soap, the molar ratio of dimerized rosin to sodium hydroxide is 1:2, and the stirring speed is 200rpm.

[0086] N3. Separate the dimerized rosin acid soap from the unreacted alkali solution and impurities by centrifugal separation, and then wash the dimerized rosin acid soap with hot water at a washing temperature of 70°C for 3 times to remove the residual alkali solution and impurities. Dry the washed dimerized rosin acid soap in a vacuum drying oven at 70°C for 6 hours to reduce the water content of the product to less than 3%. The dried product can be crushed by a pulverizer and sieved to obtain a dimerized rosin acid soap product with a 100-mesh sieve.

[0087] Preparation method of polycarboxylic acid water reducer with main chain composed of methacrylic acid and methyl acrylate copolymer and side chain composed of polyoxyethylene: P1. At 80°C, methacrylic acid, methyl acrylate, ammonium persulfate and thioglycolic acid are added dropwise to the methoxy polyethylene glycol methacrylate solution to form a mixed solution; P2. Keep the reaction at 80°C for 4 hours. After the reaction is completed, cool the reaction solution to room temperature and adjust the pH value with sodium hydroxide solution to obtain a polycarboxylic acid-based water-reducing agent product.

[0088] Specifically, the molecular weight of methoxy polyethylene glycol methacrylate is 3000, and its purity is greater than 95%. Methoxy polyethylene glycol methacrylate is uniformly stirred with water to obtain a solution with a mass fraction of 50%. Under nitrogen protection, the methoxy polyethylene glycol methacrylate solution is added to a flask and placed in a constant temperature water bath at 80°C. The molar ratio of methacrylic acid to methyl acrylate is 1:1, the amount of ammonium persulfate is 2% of the total mass of methacrylic acid and methyl acrylate, and the amount of thioglycolic acid is 0.5% of the total mass of methacrylic acid and methyl acrylate.

[0089] After the reaction was completed, the reaction solution was cooled to room temperature and the pH value was adjusted to 7 with a 30% by mass sodium hydroxide solution.

[0090] Example 1 A method for preparing carbon-fixing seawater sand concrete mixed with activated slag, comprising the following steps: S1, taking soil from the project excavation as raw material slag, and drying the taken slag by drying equipment; the slag in step S1 is dried at 100°C for 24 hours continuously; S2, the slag in step S1 is screened to obtain slag powder, the slag powder is activated by heat treatment and calcination, and the heat-activated slag powder is mixed with metakaolin and water glass and stirred to form a heat-activated slag mixture; the calcination temperature in step S2 is 700° C. The heat-activated slag powder includes silicon dioxide, aluminum oxide, calcium oxide, and magnesium oxide; the heat-activated slag: metakaolin: water glass in the heat-activated slag mixture is 1:0.2:0.25; S3, sieve the sea sand and mix it evenly with the crushed stone particles, add cement and mix to obtain a cement-based mixture; the crushed stone particles include basalt and granite, the crushed stone particles have a particle size of 5-25mm, continuous grading, and an apparent density of 2700kg / m 3； S4, mixing the activated slag soil mixture, cement-based mixture, seawater, admixtures and admixtures and placing them in a sealed carbonization box to obtain carbon-fixing seawater and sea sand concrete mixed with activated slag soil; the admixtures include silica fume, sepiolite and modified slag powder; The admixtures include retarders, air entraining agents, and water reducers. The retarders include calcium ethylenediaminetetramethylenephosphonate and borax. The air entraining agents include triterpenoid saponins and modified rosin acid soaps. The water reducers include naphthalenesulfonic acid formaldehyde condensates, polycarboxylic acid water reducers with a main chain composed of a copolymer of methacrylic acid and methyl acrylate and a side chain of polyoxyethylene. In step S4, the sealed carbonization box is connected to the carbon dioxide tank, and stirring is performed at a temperature of 70° C. and a carbonization pressure of 0.4 MPa for 4 minutes.

[0091] Calculated by mass, there are 120 parts of heat-activated slag mixture, 550 parts of sea sand, 500 parts of cement, 1,100 parts of crushed stone particles, 240 parts of seawater, 8 parts of admixture, and 50 parts of admixture.

[0092] The chloride ion solidification capacity of the activated slag mixture accounts for 70% of the total chloride ion solidification capacity of the carbon-fixing seawater sand concrete mixed with activated slag.

[0093] Example 2 A method for preparing carbon-fixing seawater sand concrete mixed with activated slag, comprising the following steps: S1, taking soil from the project excavation as raw material slag, and drying the taken slag by drying equipment; the slag in step S1 is dried at 110°C for 24 hours continuously; S2, the slag in step S1 is screened to obtain slag powder, the slag powder is activated by heat treatment and calcination, and the heat-activated slag powder is mixed with metakaolin and water glass and stirred to form a heat-activated slag mixture; the calcination temperature in step S2 is 700° C. The heat-activated slag powder includes silicon dioxide, aluminum oxide, calcium oxide, and magnesium oxide; the heat-activated slag: metakaolin: water glass in the heat-activated slag mixture is 1:0.2:0.35; S3, screen the sea sand and mix it evenly with the crushed stone particles, add cement and mix to obtain a cement-based mixture; the crushed stone particles include basalt and granite, the crushed stone particles have a particle size of 5-25mm, continuous grading, and an apparent density of 2800kg / m 3； S4, mixing the activated slag soil mixture, cement-based mixture, seawater, admixtures and admixtures and placing them in a sealed carbonization box to obtain carbon-fixing seawater and sea sand concrete mixed with activated slag soil; the admixtures include silica fume and sepiolite; The admixtures include retarders, air entraining agents, and water reducers. The retarders include borax, the air entraining agents include triterpenoid saponins, and the water reducers include calcium lignin sulfonate. In step S4, the sealed carbonization box is connected to the carbon dioxide tank, and stirring is performed at a temperature of 70° C. and a carbonization pressure of 0.4 MPa for 4 minutes.

[0094] Calculated by mass, there are 100 parts of heat-activated slag mixture, 500 parts of sea sand, 400 parts of cement, 1000 parts of crushed stone particles, 230 parts of sea water, 6 parts of admixture, and 30 parts of admixture.

[0095] The chloride ion solidification capacity of the activated slag mixture accounts for 65% of the total chloride ion solidification capacity of the carbon-fixing seawater sand concrete mixed with activated slag.

[0096] Example 3 A method for preparing carbon-fixing seawater sand concrete mixed with activated slag, comprising the following steps: S1, taking soil from the project excavation as raw material slag, and drying the taken slag by drying equipment; the slag in step S1 is dried at 110°C for 24 hours continuously; S2, the slag in step S1 is screened to obtain slag powder, the slag powder is activated by heat treatment and calcination, and the heat-activated slag powder is mixed with metakaolin and water glass and stirred to form a heat-activated slag mixture; the calcination temperature in step S2 is 750° C. The heat-activated slag powder includes silicon dioxide, aluminum oxide, calcium oxide, and magnesium oxide; the heat-activated slag: metakaolin: water glass in the heat-activated slag mixture is 1:0.2:0.5; S3, the sea sand is screened and mixed evenly with the crushed stone particles, and cement is added to obtain a cement-based mixture; the crushed stone particles include basalt and granite, the crushed stone particles have a particle size of 5-25mm, continuous grading, and an apparent density of 2600kg / m 3； S4, mixing the activated slag soil mixture, cement-based mixture, seawater, admixtures and admixtures and placing them in a sealed carbonization box to obtain carbon-fixing seawater and sea sand concrete mixed with activated slag soil; the admixtures include one or more of silica fume and modified slag powder; The admixtures include retarders, air entraining agents, and water reducers. The retarders include calcium ethylenediaminetetramethylenephosphonate and sodium carboxymethyl cellulose. The air entraining agents include modified rosin acid soap and fatty alcohol polyoxyethylene ether. The water reducers include calcium lignin sulfonate and naphthalenesulfonic acid formaldehyde condensate. In step S4, the sealed carbonization box is connected to the carbon dioxide tank, and stirring is performed at a temperature of 50° C. and a carbonization pressure of 0.4 MPa for 5 minutes.

[0097] Calculated by mass, there are 150 parts of heat-activated slag mixture, 600 parts of sea sand, 600 parts of cement, 1200 parts of crushed stone particles, 250 parts of sea water, 10 parts of admixture, and 60 parts of admixture.

[0098] The chloride ion solidification capacity of the activated slag mixture accounts for 70% of the total chloride ion solidification capacity of the carbon-fixing seawater sand concrete mixed with activated slag.

[0099] Example 4 A method for preparing carbon-fixing seawater sand concrete mixed with activated slag, comprising the following steps: S1, taking soil from the project excavation as raw material slag, and drying the taken slag by drying equipment; the slag in step S1 is dried at 100°C for 24 hours continuously; S2, the slag in step S1 is screened to obtain slag powder, the slag powder is activated by heat treatment and calcination, and the heat-activated slag powder is mixed with metakaolin and water glass and stirred to form a heat-activated slag mixture; the calcination temperature in step S2 is 700° C.; the heat-activated slag powder includes silicon dioxide, aluminum oxide, calcium oxide, and magnesium oxide; the heat-activated slag: metakaolin: water glass in the heat-activated slag mixture is 1:0.2:0.4; S3, sieve the sea sand and mix it evenly with the crushed stone particles, add cement and mix to obtain a cement-based mixture; the crushed stone particles include basalt and granite, the crushed stone particles have a particle size of 5-25mm, continuous grading, and an apparent density of 2700kg / m 3； S4, mixing the activated slag mixture, cement-based mixture, seawater, admixtures and admixtures and placing them in a sealed carbonization box to obtain carbon-fixing seawater and sea sand concrete mixed with activated slag; the admixtures include sepiolite and modified slag powder; The admixtures include retarders, air entraining agents, and water reducers. The retarders include sodium carboxymethyl cellulose and sodium gluconate. The air entraining agents include triterpenoid saponins and fatty alcohol polyoxyethylene ethers. The water reducers include calcium lignin sulfonate and naphthalenesulfonic acid formaldehyde condensates. In step S4, the sealed carbonization box is connected to the carbon dioxide tank, and stirring is performed at a temperature of 70° C. and a carbonization pressure of 0.4 MPa for 4 minutes.

[0100] Calculated by mass, there are 130 parts of heat-activated slag mixture, 540 parts of sea sand, 450 parts of cement, 1,100 parts of crushed stone particles, 240 parts of seawater, 8 parts of admixtures, and 50 parts of admixtures.

[0101] The chloride ion solidification capacity of the activated slag mixture accounts for 70% of the total chloride ion solidification capacity of the carbon-fixing seawater sand concrete mixed with activated slag.

[0102] Example 5 A method for preparing carbon-fixing seawater sand concrete mixed with activated slag, comprising the following steps: S1, taking soil from the project excavation as raw material slag, and drying the taken slag by drying equipment; the slag in step S1 is dried at 110°C for 24 hours continuously; S2, the slag in step S1 is screened to obtain slag powder, the slag powder is activated by heat treatment and calcination, and the heat-activated slag powder is mixed with metakaolin and water glass and stirred to form a heat-activated slag mixture; the calcination temperature in step S2 is 750° C. The heat-activated slag powder includes silicon dioxide, aluminum oxide, calcium oxide, and magnesium oxide; the heat-activated slag: metakaolin: water glass in the heat-activated slag mixture is 1:0.2:0.3; S3, sieve the sea sand and mix it evenly with the crushed stone particles, add cement and mix to obtain a cement-based mixture; the crushed stone particles include basalt and granite, the crushed stone particles have a particle size of 5-25mm, continuous grading, and an apparent density of 2650kg / m 3； S4, mixing the activated slag soil mixture, cement-based mixture, seawater, admixtures and admixtures and placing them in a sealed carbonization box to obtain carbon-fixing seawater and sea sand concrete mixed with activated slag soil; the admixtures include silica fume, sepiolite and modified slag powder; The admixtures include a retarder, an air entraining agent, and a water reducer. The retarder includes one or more of calcium ethylenediaminetetramethylenephosphonate and borax. The air entraining agent includes triterpenoid saponin and modified rosin acid soap. The water reducer includes a naphthalenesulfonic acid formaldehyde condensate, a polycarboxylic acid water reducer whose main chain is a copolymer of methacrylic acid and methyl acrylate and whose side chain is polyoxyethylene. In step S4, the sealed carbonization box is connected to the carbon dioxide tank, and stirring is performed at a temperature of 70° C. and a carbonization pressure of 0.4 MPa for 5 minutes.

[0103] Calculated by mass, there are 140 parts of heat-activated slag mixture, 550 parts of sea sand, 550 parts of cement, 1150 parts of crushed stone particles, 230 parts of sea water, 7 parts of admixtures, and 50 parts of admixtures.

[0104] The chloride ion solidification capacity of the activated slag mixture accounts for 75% of the total chloride ion solidification capacity of the carbon-fixing seawater sand concrete mixed with activated slag.

[0105] Comparative Example 1 The main difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, kaolin: water glass is not added to the slag powder in step S2, and in step S4, the activated slag powder, cement-based mixture, seawater, admixture and additives are mixed and placed in a sealed carbonization box, and the remaining steps and component parameters of Comparative Example 1 are the same as those of Example 1.

[0106] Comparative Example 2 The main difference between Comparative Example 2 and Example 2 is that in Comparative Example 2, all the admixtures in step S2 are silica fume. The remaining steps and component parameters of Comparative Example 2 are the same as those of Example 2.

[0107] Comparative Example 3 The main difference between Comparative Example 3 and Example 1 is that the admixture is omitted in Comparative Example 3, and the amount of admixture added is supplemented to the crushed stone particles. The remaining steps and component parameters of Comparative Example 3 are the same as those of Example 1.

[0108] Comparative Example 4 The main difference between Comparative Example 4 and Example 1 is that the admixture is omitted in Comparative Example 4, and the amount of admixture added is supplemented to the sea sand. The remaining steps and component parameters of Comparative Example 4 are the same as those of Example 1.

[0109] Comparative Example 5 The main difference between Comparative Example 5 and Example 1 is that in Comparative Example 5, the activated slag soil mixture, cement-based mixture, seawater, admixture and admixture of step S4 are mixed to obtain seawater and sea sand concrete mixed with activated slag soil. The remaining steps and component parameters of Comparative Example 5 are the same as those of Example 1.

[0110] Comparative Example 6 The main difference between Comparative Example 6 and Example 2 is that the sealed carbonization box is connected to the carbon dioxide tank, and stirring is performed at a temperature of 80° C. and a carbonization pressure of 0.4 MPa for 4 minutes. The remaining steps and component parameters of Comparative Example 6 are the same as those of Example 2.

[0111] Comparative Example 7 The main difference between Comparative Example 7 and Example 1 is that the slag in step S1 is sieved to obtain slag powder, the slag powder is mixed with metakaolin and water glass and stirred to form a slag mixture, and in step S4, the slag mixture, cement-based mixture, seawater, admixture, and admixture are mixed and placed in a sealed carbonization box. The remaining steps and component parameters of Comparative Example 7 are the same as those of Example 1.

[0112] Comparative Example 8 The main difference between Comparative Example 8 and Example 1 is that the calcination temperature in step S2 is 900° C. The remaining steps and component parameters of Comparative Example 8 are the same as those of Example 1.

[0113] Comparative Example 9 The main difference between Comparative Example 9 and Example 1 is that the ratio of thermally activated slag: metakaolin: water glass is 1:0.5:0.25. The remaining steps and component parameters of Comparative Example 9 are the same as those of Example 1.

[0114] Comparative Example 10 The main difference between Comparative Example 10 and Example 1 is that the ratio of thermally activated slag: metakaolin: water glass is 1:0.2:1. The remaining steps and component parameters of Comparative Example 10 are the same as those of Example 1.

[0115] The testing standard is the RCM method in GB / T50082-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete" for chloride ion permeability test; GB / T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete" for compressive strength and flexural strength test. GB / T50080 is used for slump test.

[0116] The test data are shown in Table 1 and Table 2: Table 1: Performance test results of Examples 1-5

[0117] Table 2: Performance test results of comparative examples 1-10

[0118] Specifically, as can be seen from Table 1, Examples 1-5 exhibit good mechanical properties, anti-permeability and processing properties. In Examples 1-5, by replacing part of the cement with heat-activated slag, after being treated with metakaolin and water glass, more silicon oxides are dissolved, which is conducive to the formation of Friedel salt, thereby improving the curing ability of chloride ions in seawater and reducing the corrosion effect of free chloride ions on steel. Examples 1-5 target the common large pores in seawater and sea sand, use admixtures and mineral admixtures to improve the chemical bonding between materials, and optimize the large pores to small pores for this purpose, combined with driven carbonization, to further improve the carbon fixation capacity, and by making good use of seawater and sea sand concrete, it is beneficial to save freshwater resources and the ecological environment, and by controlling the free chloride ion content, better durability of seawater and sea sand concrete is achieved.

[0119] As can be seen from Table 2, the compressive strength and flexural strength of Comparative Example 1 are both worse than those of Example 1. Compared with Example 1, Comparative Example 1 does not add kaolin: water glass to the slag powder in step S2, and in step S4, the activated slag powder, cement-based mixture, seawater, admixture, and admixture are mixed and placed in a sealed carbonization box. Water glass can adjust the alkaline environment of the system, which is conducive to the hydration reaction of minerals under alkaline conditions, thereby improving the strength and durability of concrete. Kaolin has high activity and can react with water glass and the like to generate a gelling product. After mixing with activated slag, the gelling properties of the mixture can be further improved, the pores caused by the lax contact between sea sand and cementitious materials can be filled, the bonding force can be enhanced, and the mechanical properties of concrete can be improved. This mixing and stirring helps to form a more uniform and dense structure at the microscopic level, fill the pores inside the concrete, reduce defects, and improve the overall performance of the concrete. Therefore, the mechanical properties and anti-permeability properties of Comparative Example 1 are worse than those of Example 1.

[0120] Comparative Example 2 Compared with Example 2, Comparative Example 2 uses all silica fume as the admixture in step S2. The fibrous structure of the sepiolite in Example 2 can form a three-dimensional network structure inside the concrete, enhancing the integrity and stability of the concrete. Sepiolite is a natural porous mineral material with an extremely high specific surface area and rich pore structure, which can significantly enhance the adsorption and fixation capacity of carbon dioxide, and can greatly improve the carbonization efficiency by working with silica fume. The porous structure of sepiolite helps to stabilize the bubbles inside the concrete, prevent the bubbles from breaking or merging, thereby optimizing the pore distribution of the concrete, and further improving its impermeability and freeze-thaw resistance. The mechanical properties and anti-permeability properties of Comparative Example 2 are worse than those of Example 2.

[0121] Compared with Example 1, Comparative Example 3 omits the admixture. Silica fume can improve the cohesiveness, impermeability, frost resistance and chemical corrosion resistance of concrete. The fibrous structure of sepiolite can form a three-dimensional network structure inside the concrete to enhance the integrity and stability of the concrete. Modified slag powder can improve the chemical corrosion resistance of concrete. Therefore, the detection performance of Comparative Example 3 is worse than that of Example 1.

[0122] Comparative Example 4 Compared with Example 1, the additive is omitted in Comparative Example 4. The retarder helps to maintain the good fluidity and plasticity of the concrete, reduce bleeding and segregation, and improve the construction quality. The air entraining agent can play a positive role in improving the workability of concrete, improving frost resistance, enhancing durability, and comprehensively improving the comprehensive performance of concrete. The water reducer can improve the compression, tension, impermeability, and frost resistance of concrete, and extend the service life of the concrete structure. The early strength of Comparative Example 4 is slightly stronger, but the later strength is worse than that of Example 4. Therefore, the detection performance of Comparative Example 4 is worse than that of Example 1.

[0123] Comparative Example 5 Compared with Example 1, in Comparative Example 5, the activated slag mixture, cement-based mixture, seawater, admixture, and admixture of step S4 are mixed to obtain seawater and sea sand concrete mixed with activated slag. In a sealed environment, a carbonization reaction occurs inside the concrete, absorbing external carbon dioxide and fixing it in the concrete structure, which helps to reduce the carbon dioxide content in the atmosphere. Carbon dioxide can react more effectively with substances such as calcium hydroxide to generate carbonization products such as calcium carbonate, thereby enhancing the mechanical properties of the concrete. Higher pressure can overcome the resistance of the internal pore structure of the concrete to the diffusion of carbon dioxide, allowing more carbon dioxide to contact and react with the active ingredients in the concrete, further improving the carbonization depth, and helping carbon dioxide to be more evenly distributed inside the concrete, avoiding excessive or insufficient local carbonization. The carbonization reaction under pressure conditions can make the internal structure of the concrete more compact, improve its impermeability and durability, and help to form a uniform and fine bubble network during the mixing process. These bubbles not only participate in the carbonization reaction, but also improve the workability and durability of the concrete. During the mixing process, the newly generated carbonization products can better fill the pores, interact with other components, and enhance the integrity of the concrete. Therefore, the detection performance of Comparative Example 5 is worse than that of Example 1.

[0124] Comparative Example 6 Compared with Example 2, in step S4 of Comparative Example 6, the sealed carbonization box is connected to the carbon dioxide tank, and stirring is performed at a temperature of 80°C and a carbonization pressure of 0.4MPa, and the stirring time is 4min. When the temperature is higher than 70°C, the evaporation rate of water inside the concrete will be significantly accelerated. During the carbonization process, excessive water evaporation leads to the destruction of the internal pore structure of the concrete, making it impossible for the generated carbonization products such as calcium carbonate to effectively fill the pores, but instead the pores increase, thereby reducing the strength of the concrete. Therefore, the detection performance of Comparative Example 6 is slightly worse than that of Example 2.

[0125] Comparative Example 7 Compared with Example 1, in Comparative Example 7, the slag in step S1 is screened to obtain slag powder, and the slag powder is mixed with metakaolin and water glass and stirred to form a slag mixture. In step S4, the slag powder, cement-based mixture, seawater, admixture, and admixture are mixed and placed in a sealed carbonization box. The calcination temperature range can effectively cause certain mineral components in the slag to undergo crystal transformation or decomposition reactions, thereby exposing more active points. The aluminosilicate minerals in the slag undergo dehydration, decomposition and other reactions to produce active amorphous phase substances, which greatly improves the activity of the slag, so that it can better synergize with cement and other cementitious materials in concrete. When calcined at 700-750°C, the internal structure of the slag is optimized and the pore structure is more reasonable. On the one hand, some unstable structural parts are removed, and on the other hand, the new structure formed is conducive to improving the adhesion between the slag and other materials, thereby improving the overall strength and durability of the concrete. Therefore, the detection performance of Comparative Example 7 is slightly worse than that of Example 1.

[0126] Comparative Example 8 Compared with Example 1, the calcination temperature of step S2 in Comparative Example 8 is 900°C, and the excessive temperature causes excessive damage to the slag structure. If the temperature is too high, some components in the slag will be over-melted or undergo irreversible chemical changes, resulting in reduced activity or the production of harmful substances. For example, silicate minerals, carbonate minerals, organic matter and glass phase substances in the slag will decompose or produce by-products, thereby affecting their ability to form gels with cement. The organic gas produced by the decomposition of organic matter will increase the porosity of the slag, affecting its density and mechanical properties. Therefore, the detection performance of Comparative Example 8 is slightly worse than that of Example 1.

[0127] Comparative Example 9 Compared with Example 1, Comparative Example 9 adjusts the ratio of heat-activated slag: metakaolin: water glass to 1:0.5:0.25. In Example 1, the heat-activated slag and metakaolin are matched in a ratio of 1:0.2. The addition of heat-activated slag and metakaolin can accelerate the early hydration reaction of concrete, improve the early strength of concrete, reduce the shrinkage deformation of concrete by optimizing the hydration reaction, improve the overall stability of concrete, and improve the impermeability, frost resistance and chemical erosion resistance of concrete by optimizing the hydration product, thereby enhancing the durability of concrete. The increase of metakaolin will lead to a decrease in the fluidity of concrete, increase the difficulty of construction, accelerate the slump loss of concrete, and affect the pumping performance of concrete. Therefore, the detection performance of Comparative Example 9 is slightly worse than that of Example 1.

[0128] Compared with Example 1, Comparative Example 10 adjusts the ratio of heat-activated slag: metakaolin: water glass to 1:0.2:1, and the heat-activated slag and water glass are matched in a ratio of 1:0.25-0.5. Water glass, as an activator, can promote the dissolution of silicon-aluminum minerals in the slag, release more active silicon dioxide and aluminum oxide, thereby enhancing the activity of the heat-activated slag, allowing it to better participate in the gelling reaction and improve the strength of the concrete. Excessive water glass cannot control the reaction speed, and the performance of the concrete will be unstable due to the too fast reaction. Therefore, the detection performance of Comparative Example 10 is slightly worse than that of Example 1.

[0129] The present invention replaces part of the thermally activated slag of cement, and after being treated with metakaolin and water glass, more silicon oxides are dissolved, which is conducive to the formation of Friedel salt, thereby improving the solidification ability of chloride ions in seawater and reducing the corrosion effect of free chloride ions on steel. The present invention makes reasonable use of seawater and sea sand concrete, is beneficial to saving freshwater resources and the ecological environment, and achieves better durability of seawater and sea sand concrete by controlling the content of free chloride ions; The present invention targets the common macropores in seawater and sea sand, adopts admixtures and mineral admixtures to improve the chemical bonding between materials, optimizes the macropores into small pores, and combines driven carbonization to further improve the carbon fixation capacity.

[0130] The above is a preferred embodiment of the present invention. Relevant personnel in this technical field may make several improvements and modifications without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing carbon-fixing seawater sand concrete mixed with activated slag, characterized in that: The following steps are involved: S1. Take soil from the project excavation as raw material slag, and dry the taken slag through drying equipment; S2, the slag in step S1 is screened to obtain slag powder, the slag powder is activated by heat treatment and calcination, and the heat-activated slag powder is mixed with metakaolin and water glass and stirred to form a heat-activated slag mixture; S3, screening sea sand and mixing it evenly with crushed stone particles, adding cement to mix to obtain a cement-based mixture; S4. The activated slag soil mixture, cement-based mixture, seawater, admixture and admixture are mixed and placed in a sealed carbonization box to obtain carbon-fixing seawater and sea sand concrete mixed with activated slag soil.

2. The method for preparing carbon-fixing seawater and sea sand concrete mixed with activated slag according to claim 1, characterized in that: Calculated by mass, the heat-activated slag mixture includes 100-150 parts, sea sand 500-600 parts, cement 400-600 parts, crushed stone particles 1000-1200 parts, sea water 230-250 parts, admixture 6-10 parts, and admixture 30-60 parts.

3. The method for preparing carbon-fixing seawater and sea sand concrete mixed with activated slag according to claim 1, characterized in that: The slag in step S1 is dried at 100-110°C for 24 hours, and the calcination temperature in step S2 is 700-750°C.

4. The method for preparing carbon-fixing seawater and sea sand concrete mixed with activated slag according to claim 1, characterized in that: The admixture includes one or more of silica fume, sepiolite, and modified slag powder.

5. The method for preparing carbon-fixing seawater and sea sand concrete mixed with activated slag according to claim 1, characterized in that: The admixtures include retarders, air entraining agents, and water reducers. The retarder includes one or more of calcium ethylenediaminetetramethylenephosphonate, sodium carboxymethyl cellulose, sodium gluconate, and borax. The air entraining agent includes one or more of triterpenoid saponins, modified rosin acid soaps, and fatty alcohol polyoxyethylene ethers. The water reducer includes one or more of calcium lignin sulfonate, naphthalenesulfonic acid formaldehyde condensate, and a polycarboxylic acid-based water reducer whose main chain is a copolymer of methacrylic acid and methyl acrylate and whose side chain is a polyoxyethylene.

6. The method for preparing carbon-fixing seawater and sea sand concrete mixed with activated slag according to claim 1, characterized in that: In step S4, the sealed carbonization box is connected to the carbon dioxide tank, and stirring is performed at a temperature of 50-70° C. and a carbonization pressure of 0.4 MPa for 4-5 minutes.

7. The method for preparing carbon-fixing seawater and sea sand concrete mixed with activated slag according to claim 1, characterized in that: The chloride ion solidification capacity of the activated slag mixture accounts for 65-75% of the total chloride ion solidification capacity of the carbon-fixing seawater sand concrete mixed with activated slag.

8. The method for preparing carbon-fixing seawater and sea sand concrete mixed with activated slag according to claim 1, characterized in that: The thermally activated slag powder includes silicon dioxide, aluminum oxide, calcium oxide and magnesium oxide.

9. The method for preparing carbon-fixing seawater and sea sand concrete mixed with activated slag according to claim 1, characterized in that: The ratio of heat-activated slag: metakaolin: water glass in the heat-activated slag mixture is 1:0.2:0.25-0.

5.

10. The method for preparing the carbon-fixing seawater and sea sand concrete mixed with activated slag according to claim 1, characterized in that: The crushed stone particles include basalt and granite, with a particle size of 5-25mm and an apparent density of 2600-2800kg / m 3 .

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