Geopolymer concrete carbonization production integrated system based on gradient carbonization principle

Abstract

The invention belongs to the technical field of geopolymer concrete carbonization production systems, and particularly relates to a geopolymer concrete carbonization production integrated system based on a cascade carbonization principle. According to the invention, through activation and utilization of the building residue soil, cement high-energy-consumption products are reduced, high-temperature flue gas can be reused for carbonization maintenance, carbon dioxide can be utilized for many times based on a gradient carbonization pressure-equalizing principle, self-sufficiency of carbon emission and carbon utilization is realized, the discharge capacity is reduced, and the energy-saving and environment-friendly effects are achieved. The product quality can be improved, the resource utilization rate can be increased, the carbon emission can be reduced, the production process can be optimized, the cost can be reduced, the combination of a traditional cement plant, a concrete mixing plant and a prefabricated component factory can be realized, and an integrated transformation scheme is provided for the carbonization production of geopolymer concrete.

Description

Technical Field

[0001] The present invention belongs to the technical field of geopolymer concrete carbonization production systems, and in particular relates to an integrated geopolymer concrete carbonization production system based on a step-by-step carbonization principle. Background Art

[0002] Currently, geopolymer concrete uses industrial solid waste (such as fly ash and slag) or construction waste as siliceous and aluminous raw materials. This material is generated through an alkaline activator reaction to form a cementitious material, offering advantages such as low carbon content, high strength, and corrosion resistance. Existing technologies have achieved laboratory-level formulation optimization and small-scale pilot production, but industrialization faces significant bottlenecks. First, the complex and fluctuating composition of construction waste makes pretreatment difficult (requiring screening, crushing, and activation), leading to increased raw material homogenization costs. Second, the geopolymer reaction is sensitive to the concentration and ratio of activators (such as sodium silicate and sodium hydroxide). Industrial production requires precise control of process parameters (temperature, humidity, and reaction time), resulting in high equipment investment and maintenance costs.

[0003] At present, the efficiency of carbonization reaction is significantly affected by the mineral composition and pore structure of the raw materials. Inert impurities in construction waste (such as unburned organic matter) will hinder the diffusion of CO2, resulting in uneven carbonization. Secondly, the industrial-grade carbonization reaction comes from the collection of carbon dioxide after treatment of industrial waste gas, and there is heat waste and additional carbon emissions in the whole process. Thirdly, since industrial-grade carbonization requires a huge amount of carbon dioxide, the amount of carbon dioxide absorbed in the reactor is limited, resulting in a large amount of external emission waste.

[0004] Therefore, how to make full use of the significant carbon sequestration potential of construction waste polymer concrete combined with stepped carbonization technology, from the perspective of integrated raw material supply to carbonization curing and molding, to complete the closed loop of carbon emission and utilization, and at the same time, complete the production of construction waste polymer concrete carbonization curing components is of great significance. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of the aforementioned carbonization reaction, such as uneven carbonization, heat waste and additional carbon emissions, and the limited carbon dioxide absorption in the reactor leading to large amounts of wasteful emissions. The present invention provides an integrated carbonization production system for geopolymer concrete based on the principle of stepwise carbonization. The present invention adopts the following technical solutions: The integrated system for carbonization production of geopolymer concrete based on the principle of cascade carbonization includes the following steps: S1. Soil is taken from the project excavation as raw material, and the excavated soil is dried by drying equipment. The excavated soil is sieved to obtain powder, aggregate, and other types of excavated soil. The powder is heat-treated and calcined, and the calcined flue gas is injected into the flue gas storage tank. The powder, aggregate, and other types of excavated soil are then transferred to the storage tank; S2. Evenly mixing the powder and aggregate obtained in step S1 with the liquid, admixture, and additive to obtain geopolymer concrete. The precast components obtained from the geopolymer concrete are sent to a pre-curing room for pre-curing. S3. The flue gas storage tank in step S1 and the carbon dioxide replenishing device form a gas source device. The prefabricated components pre-cured in step S2 are fed into multiple series-connected kettles for carbonization curing. The gas source device is connected to each kettle, and the residual gas from the previous kettle is transferred to the next kettle. A gas concentration gradient is formed between the kettles, and the gas source device can replenish the gas concentration of each kettle. S4. The prefabricated components that have undergone carbonization curing in step S3 enter the natural curing stage, and the prefabricated components that have reached the design strength are transported to the project site for hoisting and installation.

[0006] The present invention forms a complete integrated production system, starting from the acquisition of raw materials, to the production of geopolymer concrete, pre-curing and carbonization curing of prefabricated components, and finally to natural curing and transportation to the project site for installation. Each link is closely connected and coordinated, which improves production efficiency and reduces the connection cost and time loss of intermediate links. It can improve product quality, increase resource utilization, reduce carbon emissions, optimize production processes and reduce costs, and help provide high-quality carbonization-cured prefabricated components for construction projects.

[0007] Specifically, taking soil from the project excavation as raw material slag can effectively utilize construction slag and expand the source of raw materials for geopolymer concrete. The present invention classifies slag into powder, aggregate and other types of slag through pre-treatment operations such as drying and screening, which can better control the quality of raw materials and make the various components of geopolymer concrete more homogeneous and stable, overcoming the problems caused by the complex composition and large fluctuations of construction slag. The present invention mixes the processed powder, aggregate with liquid, admixture and admixture to form geopolymer concrete, and utilizes the advantages of geopolymer concrete itself such as low carbon, high strength and corrosion resistance to produce products with excellent performance, thereby meeting the requirements for high quality and environmental protection of building materials.

[0008] The present invention utilizes multiple series-connected kettles for carbonization curing, transferring residual gas from the preceding kettle to the succeeding kettle, creating a gas concentration gradient between the kettles. This effectively addresses the previously observed uneven carbonization reaction. This concentration gradient guides the carbon dioxide gas gradually deeper into the prefabricated components, allowing them to fully react with the components according to the gas concentration gradient. This avoids uneven carbonization caused by inert impurities and ensures consistent carbonization and quality stability across the entire prefabricated component.

[0009] In addition, by forming a gas source device with the flue gas storage tank and the carbon dioxide replenishing device, the flue gas generated during the calcination process is fully utilized, and resource recycling and reuse is realized. Moreover, the gas source device is connected to each kettle body, and can replenish the gas concentration of each kettle body. Combined with the transfer of residual gas between kettle bodies, carbon dioxide is efficiently utilized in the entire carbonization system, minimizing the waste of external emissions caused by the limited absorption of carbon dioxide in the reactor, and reducing the waste of carbon dioxide resources. Compared with traditional industrial-grade carbonization reactions that have heat waste and additional carbon emissions, the present invention avoids additional heat loss and unnecessary carbon emissions by utilizing calcination flue gas, thereby reducing carbon emissions from the source.

[0010] Furthermore, calculated by mass, the geopolymer concrete includes 100-150 parts of heat-activated slag soil mixture, 500-600 parts of aggregate, 1000-1200 parts of crushed stone particles, 230-250 parts of water, 45-60 parts of admixture, and 30-60 parts of additives.

[0011] Specifically, the construction waste of the present invention is taken from engineering waste disposal sites, open-air stacking and mixing stations, and the construction waste is passed through an industrial-grade three-pass drum dryer with a drying temperature of 105°C and a drying time of 24 hours to allow free water and hygroscopic water to fully evaporate, ensuring that the waste is almost completely dry, that is, the moisture content is close to 0%.

[0012] Specifically, the completely dried slag is passed through an industrial screening machine to be screened into powder (less than 1.2 mm) and other categories. The powder can be mixed with other materials (such as cement raw materials) and mixed into a high-temperature calcination rotary kiln. The mixed powder is used for high-temperature calcination. At the same time, the emitted flue gas is injected into the flue gas storage tank after desulfurization, denitrification and dust removal, and the mixed powder is transferred to the powder storage tank.

[0013] Specifically, other types of slag are screened in spiral sand washers and then stored in fine aggregate storage tanks (particle size 1.2-4.75mm), coarse aggregate storage tanks (particle size 4.75-20mm), and other tanks. The slag and gravel particles in these tanks can be used for backfilling roadbeds and preparing geopolymer concrete. Furthermore, powders such as admixtures and additives are stored in steel silos, while liquids such as alkali activators and water are stored in steel containers.

[0014] Specifically, the heat-activated slag mixture is composed of powder and cement raw material in a mass ratio of 4:6. The cement raw material is composed of limestone, clay, and steel slag. After heat activation, the silica-alumina mineral structure within the heat-activated slag mixture is optimized, increasing the number of active sites and enabling better reaction with alkaline activators to form a cementitious material. During the formation of geopolymer concrete, this helps enhance the overall cementitious properties, making the concrete's internal structure denser, improving its strength and stability, and fully leveraging the inherent high strength of geopolymer concrete, thereby improving the load-bearing capacity of precast components and their ability to resist external forces.

[0015] Specifically, the mass ratio of fine aggregate to coarse aggregate in the aggregate is 1:2. Aggregate plays a supporting role in concrete. The appropriate amount of aggregate effectively fills the internal spaces of the concrete, resulting in a more optimal particle size distribution for geopolymer concrete, reducing porosity and increasing density. This not only helps to improve the concrete's compressive strength but also enhances its volume stability, reducing the risk of deformation during use due to factors such as temperature fluctuations and alternating dry and wet conditions, thereby ensuring the dimensional accuracy and long-term performance of precast components.

[0016] Specifically, crushed stone particles possess high hardness and strength. In geopolymer concrete, they reinforce the overall material's skeletal structure, working in conjunction with the aggregate to bear greater external loads and enhance the geopolymer concrete's compressive and flexural strength. Furthermore, crushed stone particles enhance the wear resistance of the concrete surface, making it more suitable for construction applications requiring high wear resistance, such as prefabricated components in ground structures like roads and parking lots, thereby extending the component's service life.

[0017] Specifically, a water content of 230-250 parts per million ensures thorough mixing of the solid raw materials, ensuring good fluidity and plasticity in the geopolymer concrete. This facilitates pouring and molding operations during precast component production, allowing the concrete to better fill molds and ensure the precast components maintain their shape and dimensions. The appropriate water content promotes the chemical reactions between the various components, promotes the formation of cementitious materials, and further improves the overall performance and uniformity of the concrete.

[0018] Specifically, admixtures can improve the performance and durability of geopolymer concrete, making it more adaptable to different construction environments and usage requirements. Admixtures such as water reducers can reduce water usage while maintaining concrete performance, further improving its strength. Air-entraining agents can introduce tiny bubbles, improving freeze-thaw resistance. Retarders can adjust the setting time of concrete, facilitating construction operations. Alkaline activators react with heat-activated powder and raw cement to form a cementitious material. During the formation of geopolymer concrete, they help enhance the overall cementitious properties, making the internal structure denser and improving its strength and stability.

[0019] Specifically, admixtures include fly ash and slag. These admixtures can partially replace traditional cementitious materials like cement, reducing production costs. Furthermore, they continue to exert their own activity, participating in geopolymer reactions, further optimizing the concrete's microstructure and improving its density, impermeability, and other properties.

[0020] Furthermore, other types of slag are screened and loaded into fine aggregate storage tanks, coarse aggregate storage tanks and other tanks respectively. The other tanks are used to store crushed stone particles. The fine aggregate storage tank is used to store aggregates with a particle size of 1.2-4.75mm, and the coarse aggregate storage tank is used to store aggregates with a particle size of 4.75-20mm. The powder particle size is less than 1.2mm, and the crushed stone particle size is greater than 20mm.

[0021] Aggregates of different particle sizes form a more reasonable particle gradation when geopolymer concrete is formulated. This helps improve the working properties of concrete, such as fluidity and plasticity, making it easier to distribute evenly during the casting process and ensuring uniform performance in all parts of the precast component. Fine aggregates with smaller particle sizes can fill the voids in the skeleton formed by coarse aggregate, further reducing the porosity within the concrete, making the concrete structure more compact, and improving its compressive strength, impermeability and other performance indicators. For some precast components with high requirements for surface flatness and relatively thin thickness, the proportion of fine aggregate can be appropriately increased to achieve a more delicate surface effect; for precast components that need to withstand greater loads and have thicker structures, the amount of coarse aggregate can be increased to strengthen its skeleton support.

[0022] Furthermore, the drying temperature in step S1 is 100-110° C. for 24 consecutive hours, and the calcination temperature includes a low-temperature stage of 300-500° C., a dehydration stage of 500-700° C., and a calcination stage of 700-750° C.

[0023] Specifically, setting the drying temperature at 100-110°C for 24 hours can thoroughly remove free water and some bound water from the soil. Excessive moisture content can affect subsequent processing steps such as screening and mixing, as well as the performance of geopolymer concrete. This relatively mild temperature range prevents the destruction of active components in the soil or the initiation of unnecessary chemical reactions, thereby preserving the soil's original mineral composition and chemical activity to the greatest extent possible.

[0024] Specifically, the reaction activity of slag powder is stimulated by high-temperature calcination, which is mainly manifested in that high-temperature calcination converts clay minerals (such as kaolin) in the slag powder into metakaolin, which increases the dissolution rate of silicon and aluminum components, and then reacts with alkaline activators to generate a dense matrix structure, forming a polymer gelling material with a three-dimensional network structure.

[0025] Specifically, kaolin minerals in construction waste ( ) undergoes dehydroxylation reaction at high temperature, releasing structural water in stages: Low-temperature stage (300-500°C): Adsorbed and interlayer water evaporates, leading to initial expansion of the mineral structure. During the low-temperature calcination stage at 300-500°C, previously relatively stable components such as silicoaluminous minerals begin to activate, exposing more active sites. These active sites are subsequently better able to react with alkaline activators, thereby improving the cementitious properties of the geopolymer concrete and enhancing the cohesive strength of its internal structure, contributing to the strength and overall stability of the resulting precast components. The temperatures at this stage allow for the decomposition and volatilization of volatile impurities and unburned organic matter in the slag, achieving initial impurity removal and minimizing their adverse effects on subsequent geopolymer reactions and carbonation curing. This, for example, avoids uneven carbonization caused by organic matter hindering carbon dioxide diffusion.

[0026] Specifically, the key dehydration stage (500-700℃): When the temperature rises to the dehydration stage of 500-700℃, the deep-seated bound water in the slag can be further removed, allowing the raw materials to reach a higher degree of dryness. This temperature range will also promote the further optimization of the mineral structure in the slag, causing the crystal structure of components such as silica-alumina minerals to change, and the lattice energy to decrease, further activating the activity of the raw materials, enhancing their participation in the geopolymer reaction, and improving the ability of geopolymer concrete to generate cementitious materials, thereby improving the performance indicators of prefabricated components. Specifically, the hydroxyl group (-OH) is separated, the layered crystal structure is destroyed, and an amorphous / semi-crystalline metakaolin ( ), its atomic arrangement is disordered, the specific surface area is increased, and the active sites are exposed. It avoids the crystallization phase (>900℃ forms mullite), which meets the activity requirements. , has not yet decomposed on a large scale at 700℃ (decomposition temperature is about 825℃), which can reduce the free Generation, causing the alkalinity of the geopolymer system to fluctuate or Precipitation.

[0027] ( ) During the calcination stage at 700-750°C, the active components such as silica-alumina minerals in the slag are fully activated, and the internal chemical bonds are broken and reorganized to generate more highly active amorphous phase substances. After mixing with alkaline activators, these substances can react quickly and fully to generate high-quality cementitious materials, significantly enhancing the strength and durability of geopolymer concrete. After this stage of calcination, the mineral composition and activity of the raw materials basically reach a stable state. Preferably, the calcination temperature is set at 700°C, and the activity index changes after calcination at 700°C for 7 hours: XRD amorphous peak intensity: the peak band is slightly narrow, and a weak quartz peak may appear (the raw material contains quartz), and the amorphous peak accounts for ≥95%. BET specific surface area: 15m 2 / g or more. Volcanic ash activity index (28d): 100%-105%.

[0028] Furthermore, the geopolymer concrete is weighed, mixed and stirred according to a proportion, and quantitatively distributed into the component mold by a distribution machine, and then vibrated and compacted by a distribution turnover platform.

[0029] Specifically, during the mixing stage of geopolymer concrete, material weighing is primarily divided into aggregate, powder, and liquid weighing. All weighing is performed independently, using electronic scales and microcomputer control, with accuracy controlled to ≤2% for aggregate and ≤1% for powder, water, and admixtures. The materials are weighed and mixed according to the established ratio, using a twin-shaft forced concrete mixer. The materials are evenly distributed in fixed quantities into the component molds via a concrete distributor, and then vibrated and compacted using a concrete distribution platform.

[0030] Based on the “three-stage dispersion method” mixing sequence, the preparation of geopolymer concrete includes the following steps: T1: Place the mixture of coarse and fine aggregates and activated soil into a mixer and dry mix for 60-90 seconds at a medium speed (80-120 r / min). The purpose is to evenly cover the aggregate surface with cementitious material, disperse cementitious material agglomerates, and avoid segregation of wet-mixed aggregates and the formation of dry powder balls that are difficult to disperse. T2: Premixing the activator, admixtures, and additives + wet mixing: Dissolve solid NaOH in water in advance. After cooling, mix with water glass in a mass ratio of 2:8 and stir thoroughly. Pour the premixed activator solution, admixtures, and additives into a blender at a uniform speed. Stir at a low speed (50-80 rpm) for 120-180 seconds to ensure that the aggregate and cementitious material are fully wetted. Stir until no dry powder particles are visible and the aggregate surface is completely coated with the paste.

[0031] T3: Adjustment and Homogenization: Place the crushed stone particles into the mixer. Add a small amount of water according to the established mix ratio and based on fluidity. Once all water is added, mix at high speed (150-200 rpm) for 30 seconds to quickly improve uniformity. Then, mix at low speed (50-80 rpm). The total wet mixing time should not exceed 5 minutes to avoid premature hydration and excessive coagulation.

[0032] Specifically, thorough mixing allows for a uniform distribution of raw materials of varying particle sizes and properties within the concrete. For example, admixtures can be evenly dispersed throughout the system, better maximizing their effectiveness in regulating performance and improving durability. Fine aggregate can fully fill the gaps between coarse aggregates, creating a more balanced particle size distribution and a denser, more uniform concrete structure. This helps avoid localized performance variations caused by uneven raw material distribution, ensuring consistent quality and performance across all parts of precast components and enhancing overall reliability and stability.

[0033] Specifically, the use of a concrete placing machine for quantitative placement can accurately control the amount of material placed based on the size and shape of the component mold and the required amount of concrete. This can effectively avoid waste caused by excessive material placement and the subsequent need to clean up excess concrete. It also prevents situations where insufficient material placement leads to incomplete component formation and defects, thereby ensuring the dimensional accuracy and appearance quality of prefabricated components and improving material utilization and finished product qualification rates during the production process.

[0034] Specifically, after laying, the concrete is vibrated and compacted using a distribution platform. This vibration expels air from the concrete, further reducing the gaps between particles and allowing the materials to bind more tightly together. This improves the density of the concrete, avoids defects like honeycombing and holes, and creates a smoother surface for the precast components. This increased density helps enhance the compressive strength and impermeability of the precast components, allowing them to better withstand external loads and resist erosion from the outside environment, extending their service life.

[0035] Furthermore, the pre-curing in step S2 adopts a constant temperature and humidity environment, the temperature is controlled at 20-25°C, the humidity is maintained at above 95%, and the curing time is 24 hours.

[0036] The present invention first forms a supporting skeleton and retains the reaction potential through light polymerization, and then uses the carbonization process to activate the remaining activity, ultimately achieving the synergistic enhancement effect of "prepolymerization-carbonization-final coagulation".

[0037] The pre-curing process of this invention is not simply a matter of "waiting for solidification." Instead, it precisely controls five dimensions: mechanics, moisture, activity, process, and defects. This creates a reaction platform for carbonization curing that boasts a stable structure, optimal humidity, and controllable activity. The goal of pre-curing is to generate a small amount of gel through the initial polycondensation reaction of aluminosilicates, forming a rigid framework capable of withstanding the flow pressure of carbon dioxide gas. Simultaneously, the moisture in the pre-curing slurry slowly penetrates the pores of the aggregate, promoting the formation of nano-sized gel particles at the interface and enhancing the bond between the aggregate and the slurry.

[0038] Specifically, the assembly line automatically transports components from the vibrating distribution platform into the pre-curing room. Pre-curing is carried out in a constant temperature and humidity environment, controlled at 20-25°C and maintained at above 95%. Curing lasts for 24 hours, and the component strength reaches 15%-20% of the design strength, meeting the mechanical demolding force requirements and preventing damage to corners caused by premature demolding. Demolding is then completed. Pre-curing not only promotes a full reaction, accelerating the chemical reaction between the alkali-activated material in the geopolymer and the silicon-aluminum raw material to form a stable three-dimensional network structure, but also evaporates excess water in the pores, creating conditions for carbonization curing.

[0039] Specifically, at a temperature of 20-25°C, the reaction between the heat-activated slag-soil mixture, admixtures, and alkaline activators proceeds smoothly. This prevents the chemical reaction rate from being too slow due to low temperatures, leading to prolonged setting and hardening times and insufficient early strength development in the concrete. It also prevents undesirable phenomena such as excessive evaporation of water and internal temperature stresses in the concrete due to high temperatures. This reduces the likelihood of quality defects such as cracking and uneven strength caused by temperature factors, ensuring the quality stability of precast components. A temperature of 20-25°C helps generate more high-quality cementitious materials, steadily improving the internal structural strength of geopolymer concrete.

[0040] Specifically, a high humidity environment provides sufficient moisture for the formation of the cementitious material in geopolymer concrete. Sufficient humidity ensures the reaction proceeds continuously, preventing interruptions or incomplete reactions caused by insufficient moisture. This promotes the production of more hydration products, enhances the concrete's bonding properties, creates a denser internal structure, and improves the overall strength and durability of precast components. Maintaining high humidity effectively prevents rapid surface moisture loss from geopolymer concrete, as this can cause surface shrinkage and, in turn, shrinkage cracks, compromising the appearance and structural integrity of precast components.

[0041] Specifically, a 24-hour curing period can give geopolymer concrete enough time to develop early strength. The chemical reactions between the various components continue, and the cementitious materials are continuously generated and filled in the pores of the concrete, so that the concrete gradually changes from a plastic state to a hardened state with a certain load-bearing capacity. This ensures that the prefabricated components have sufficient strength in subsequent demolding, transportation and other operations, and are not prone to breakage, deformation, etc., thereby improving the yield of the production process.

[0042] Furthermore, the calcined flue gas in step S1 is sent to a dust collector for dust removal after being cooled by a heat exchanger to cool the high-temperature decomposition gas, and then sent to a desulfurization bed, a drying bed, and a precision adsorption bed for desulfurization, drying, dust removal, and removal of nitrogen oxides, and finally sent to a flue gas storage tank.

[0043] The carbon dioxide used in the carbonization curing of the present invention is preferably obtained by using the flue gas generated by the high-temperature calcined slag rotary kiln and subjected to desulfurization, denitrification and dust removal treatment, and the deficiency is supplemented by a carbon dioxide tanker.

[0044] The high-temperature rotary kiln flue gas used in this process uses external combustion technology to heat the raw meal fed into the high-temperature calcining rotary kiln. This heats the raw meal inside the kiln by burning fuel outside the kiln, producing a high concentration of CO2. Furthermore, since the fuel and material are not in direct contact, the decomposed calcium oxide is highly active and can directly absorb SOx released from the raw material. The high-temperature decomposed gas is first cooled in a heat exchanger before being sent to a dust collector for dust removal. It is then sent to a desulfurization bed, a drying bed, and a precision adsorption bed for further desulfurization, drying, dust removal, and removal of impurities such as nitrogen oxides before being sent to a flue gas storage tank. The waste heat from the fuel combustion flue gas and the residual heat from the high-temperature CO2 cooling can be recovered in a waste heat boiler to generate electricity or used to preheat the air required for fuel combustion.

[0045] Specifically, calcination flue gas is typically very hot. If it enters subsequent equipment such as dust collectors and desulfurization beds directly, the high temperature could damage these components, affecting their normal operation and service life. Using a heat exchanger to cool the high-temperature decomposition gas brings the flue gas temperature down to a level that can be tolerated by subsequent treatment equipment. This avoids problems such as increased equipment maintenance costs and process interruptions caused by high temperatures, ensuring the continuity and effectiveness of the entire flue gas treatment process.

[0046] Specifically, calcination flue gas often contains a large amount of particulate matter. Dust removal by a dust collector can effectively intercept and remove solid particulate matter such as dust and fly ash from the flue gas, making the exhaust gas cleaner and reducing dust pollution to the atmospheric environment. Flue gas is sent to a desulfurization bed for desulfurization treatment. The desulfurizer reacts chemically with sulfur dioxide, converting it into a relatively harmless substance, thereby significantly reducing the sulfur dioxide content in the flue gas. Using a precision adsorption bed to remove nitrogen oxides from the flue gas can accurately capture and remove nitrogen oxides, further purifying the flue gas and reducing nitrogen oxide emissions into the atmosphere.

[0047] Specifically, high humidity can affect the further utilization and storage of flue gas. Drying the flue gas in a drying bed removes excess moisture, bringing the flue gas to an appropriate dryness level. This facilitates long-term storage of the flue gas in storage tanks and prevents corrosion of the storage tanks or degradation of flue gas quality due to condensation.

[0048] Furthermore, the carbon dioxide replenishing device includes a carbon dioxide tanker and an electric heating vaporizer. The carbon dioxide tanker is equipped with a low-temperature liquid CO2 storage tank. The electric heating vaporizer has a power of 50kW and controls the heating rate at 0.5-1.0m 3 / min.

[0049] Carbon dioxide tanker replenishment: The tanker is equipped with a low-temperature liquid CO2 storage tank (-196℃), and the heating rate (0.5-1.0m 3 / min) to avoid a sudden drop in the temperature inside the kettle caused by direct introduction of gas.

[0050] Specifically, CO2 tankers are equipped with cryogenic liquid CO2 storage tanks, enabling large quantities of CO2 to be stored and transported in liquid form. Compared to gaseous storage, liquid CO2 can hold more CO2 in the same volume, greatly improving storage efficiency. This can reduce the frequency of CO2 replenishment and reduce transportation and other related costs. It also ensures sufficient CO2 reserves during the carbonation maintenance process, avoiding production interruptions due to insufficient gas supply and ensuring production continuity.

[0051] Specifically, the 50kW electric heating vaporizer reduces the operating cost of the entire carbon dioxide replenishment device, controls the heat supply rate at 0.5-1.0m³ / min, and can stably convert cryogenic liquid CO2 into gaseous carbon dioxide at a set rate, ensuring that the carbon dioxide flow entering each kettle body for carbonization curing is uniform and the concentration is stable. This helps maintain a good gas concentration gradient between the kettle bodies, ensuring that the carbonization curing reaction proceeds smoothly and orderly, and avoiding problems such as uneven carbonization and low reaction efficiency caused by too fast or too slow carbon dioxide supply rate.

[0052] Furthermore, the prefabricated components are cured separately in series with kettles arranged along the steps, the number of kettles is at least four, and the remaining gas of the last kettle is discharged or connected to the gas source device.

[0053] Specifically, the multi-reactor cascade carbonization process improves the CO2 utilization rate to more than 85% through the "equal pressure connection-gradient utilization-residual gas reuse" method, and realizes the efficient flow of gas among multiple reactors through pressure balance and concentration gradient design.

[0054] 1) Ideal gas state equation The formula for equalizing pressure after connection: , usually the pressure in the kettle is consistent with the atmospheric pressure before the gas is injected. , the amount of CO2 obtained in kettle 2 , realize unpowered gas redistribution and avoid direct waste.

[0055] 2) Mass transfer driving force formed by concentration gradient The prefabricated components that have undergone pre-curing are sent into kettle 1, kettle 2, kettle 3 and kettle 4 in sequence through the assembly line. The carbonization curing time is 7 hours. Carbon dioxide is injected into kettle 1 through a flue gas storage tank or a carbon dioxide tanker via a gas source device. Carbonization curing can be achieved by using the equalization pressure principle. Starting from kettle 1, part of the residual gas after the reaction is injected into kettle 2. Similarly, carbonization curing can be achieved in kettles 3 and 4. The carbon dioxide content in the residual gas that cannot be used after the entire batch reaction is less than 10%, which is discharged or collected for reuse. The entire carbonization curing has high utilization efficiency.

[0056] The first stage (high-concentration reaction in kettle 1): The prefabricated component is placed in kettle 1, and the CO2 concentration is 15%–20%. It preferentially reacts with the highly active sites on the surface of the component to form a dense carbonate shell. The second stage (equalizing the pressure to kettle 2 and replenishing the gas): the prefabricated components are transferred to kettle 2, and the residual gas after the reaction in kettle 1 is injected into kettle 2. A small amount of new gas is added until the concentration is between 10% and 15%. The remaining CO2 diffuses into the middle layer of the component and reacts with the secondary active sites. At this time, the shell layer formed on the surface can guide the gas to penetrate into the interior to avoid "short circuit"; The third stage (equalizing the pressure to kettle 3 and supplementing the gas): the prefabricated components are transferred to kettle 3, and the residual gas after the reaction in kettle 2 is injected into kettle 3, and a small amount of new gas is added until the concentration is between 5% and 10%; The fourth stage (equalizing the pressure to kettle 4 and supplementing the gas): the prefabricated components are transferred to kettle 4, and the residual gas after the reaction in kettle 3 is injected into kettle 4, and a small amount of new gas is supplemented until the concentration is between 3% and 8%; Of course, in some embodiments, the prefabricated components that have passed the third stage can be transferred directly, and part of the residual gas in kettle 3 is transferred to kettle 4 and then directly discharged or transferred to other equipment connected to the gas source device. The reaction-pressure equalization process is repeated, so that low-concentration CO2 is "extracted" step by step in multiple kettles, and the final exhaust gas concentration can be reduced to below 5% (the traditional exhaust gas concentration of a single kettle is about 15%).

[0057] 3) Concentration-pressure linkage control: When the CO2 concentration of kettle 1 is less than 15% and the pressure is less than 105kPa, first connect kettle 2 to equalize the pressure, and then calculate the gas supply volume based on the concentration difference (target 15%) (Formula:

[0058] Kettles 2, 3, and 4 use a "pressure equalization before gas replenishment" approach to avoid direct high-pressure gas replenishment, which can cause pressure shock on component surfaces (pressure surge rate ≤ 5kPa / min). Compared to replenishing high-pressure gas while the same kettle is already under a certain pressure, this approach reduces the impact of gas replenishment on the prefabricated component surfaces. Naturally, gas delivery can be stopped when the gas concentration in the kettle is within the operating range.

[0059] Specifically, a CO2 consumption model was established based on historical data. When multiple reactors are linked together, the gas consumption per unit component of a single reactor is reduced by 35% compared to when a single reactor operates independently (taking a 100mm thick wall panel as an example, it is reduced from 12kg / m³ to 7.8kg / m³).

[0060] The present invention sets at least four kettle bodies in series, which can build a continuous carbon dioxide concentration gradient between the kettle bodies. As the prefabricated components pass through these kettle bodies in sequence, carbon dioxide gradually flows from the front kettle body with a higher initial concentration to the rear, and its concentration decreases in each kettle body in sequence. This concentration gradient allows carbon dioxide to fully react with all parts and layers of the prefabricated components. In the front kettle body with a high concentration, carbon dioxide can first fully react with the high-activity sites on the surface of the component, and as the concentration decreases, it enters the subsequent kettle body and can continue to penetrate into the interior of the component to react with the secondary active sites, thereby achieving more comprehensive and fuller utilization of carbon dioxide gas, avoiding the waste caused by the discharge of gas due to insufficient reaction in a single kettle body, greatly improving the utilization rate of carbon dioxide, and reducing production costs and carbon emission pressure on the environment.

[0061] Optionally, in some embodiments, when the residual gas from the last kettle is connected to the gas source device, the residual gas is recycled and reused. Even after the reaction and utilization of the previous kettles, the residual gas may still contain a certain amount of carbon dioxide. After being reintroduced into the gas source device and processed accordingly, it can be used again in the carbonization and curing process of each kettle, forming a closed loop of gas resource recycling, further reducing the amount of additional carbon dioxide replenished, and lowering production costs.

[0062] Optionally, in some embodiments, when the residual gas is discharged, the carbon dioxide content in the residual gas is relatively low due to the "step-by-step extraction" of multiple kettles. The discharged residual gas has little impact on the environment and meets the requirements of environmental emission standards.

[0063] Specifically, if the prefabricated components are cured in the same kettle for 7 hours and the carbon dioxide concentration of the input gas source is maintained at 15-20%, the surface of the prefabricated components will carbonize too quickly, hindering the internal reaction, resulting in insufficient carbonization depth, decreased utilization in the later stage of the reaction, resulting in CO2 waste, and concentrated reaction heat, thereby exacerbating temperature stress.

[0064] Specifically, if the initial carbon dioxide concentration of the input gas source of the prefabricated components in the same kettle body is 20% and cured for 7 hours, several situations may occur. First, under ideal conditions, during the 7 hours in the same kettle body, without adding carbon dioxide, the initial carbon dioxide concentration will drop from 20% to below 10%, and the prefabricated components can successfully complete the 7-hour curing.

[0065] Second, the same kettle is continuously monitored and the consumption rate of carbon dioxide is higher than expected. New carbon dioxide is added after 2 hours, and then again after 2 hours of full reaction, and then again after 3 hours of full reaction or the gas is directly discharged. Such operation, directly adding high-pressure gas under a certain pressure, is likely to cause pressure shock on the surface of the component, resulting in increased local brittleness.

[0066] Third, continuous monitoring of the same kettle body shows that the consumption rate of carbon dioxide is lower than expected. It is necessary to discharge some carbon dioxide after 2 hours, discharge some carbon dioxide again after 2 hours of full reaction, and discharge some carbon dioxide again after 3 hours of full reaction to continue the reaction or directly discharge the gas. Such operations will result in direct waste of some unused carbon dioxide.

[0067] Optionally, in some embodiments, the present invention provides multiple kettle bodies. At the initial stage of the reaction, the valve bodies of two adjacent kettle bodies are opened. After the adjacent kettle bodies are pressurized, the concentration of the latter kettle body will be lower than the expected concentration. Without emitting carbon dioxide and causing waste, the workpiece is transferred to the next kettle body through the assembly line, the valve bodies of the two adjacent kettle bodies are closed, and the kettle bodies form a sealed space. The carbon dioxide concentration in the kettle body is replenished or not, and then the reaction continues.

[0068] Alternatively, in some embodiments, the present invention employs multiple kettles. At the end of the reaction, the valves of two adjacent kettles are opened. After the pressures in the adjacent kettles are equalized, the concentration in the next kettle approaches the expected concentration. Without wasting carbon dioxide, the workpiece is transferred to the next kettle via an assembly line, and carbon dioxide is replenished or not replenished depending on the concentration of the kettle. The valves of the two adjacent kettles are closed, forming a sealed space within the kettle, and the reaction then continues.

[0069] Optionally, in some embodiments, when the prefabricated component moves out of the previous kettle body, the cavity of the previous kettle body is opened, and the cavity of the next kettle body is opened and connected. The prefabricated component can be transferred to the next kettle body through a mobile conveying chain on the assembly line, or a clamp or a manipulator and other equipment. By closing the valve body of the kettle body and the kettle body cavity, the prefabricated component can react with carbon dioxide in the next kettle body.

[0070] Through the initial 15%-20% rapid reaction of carbon dioxide, the mid-term stable penetration of 10%-15% carbon dioxide, and the late 5%-10% deep carbonization of carbon dioxide, the "shell effect" can be avoided, making the carbonization depth of prefabricated components more uniform, with better compressive strength and durability, and a low risk of microcracks.

[0071] Optionally, in some embodiments, the carbon dioxide content in the tail gas of the present invention is much greater than the carbon dioxide content in the air, and can be discharged into a recovery device for condensation and circulated to a carbon dioxide tanker for standby use.

[0072] Optionally, in some embodiments, the carbon dioxide in the tail gas of the present invention can be transferred to a flue gas storage tank and mixed with the original carbon dioxide that has undergone desulfurization, denitrification and dust removal, and then further transferred to the gas source device.

[0073] Optionally, in some embodiments, the carbon dioxide in the tail gas of the present invention can be transferred to a gas source device to dilute the high concentration of carbon dioxide.

[0074] Furthermore, step S4 also includes carbonized layer defect repair and efflorescence treatment.

[0075] Specifically, during the carbonization curing process, some defects in the carbonized layer may appear, such as localized uneven carbonization, tiny pores, or weak areas. By repairing carbonized layer defects, filling pores, and strengthening weak areas, the structure of the carbonized layer becomes denser and more uniform, thereby improving the overall quality of the prefabricated component. Its ability to resist the penetration of external corrosive media is enhanced, which can effectively delay the occurrence of problems such as internal steel corrosion in the component, greatly improving the durability of the prefabricated component during long-term use.

[0076] Specifically, if there are "honeycomb-like" uncarbonized areas on the surface (area > 5%), apply 1% sodium silicate solution (modulus 2.0) with a brush to promote secondary carbonization of the surface (the strength of the defective area will increase to more than 90% of the surrounding area within 7 days).

[0077] Specifically, the efflorescence phenomenon usually causes white stains and streaks to appear on the surface of prefabricated components. The precipitated alkaline substances may continue to react with substances such as carbon dioxide in the air, further affecting the performance of the component surface. For example, it may cause the surface to become loose and peeling, affecting the aesthetics of components such as decorative prefabricated components and facade components. Through efflorescence treatment, these efflorescence traces that affect the appearance can be effectively removed, and the original color and texture of the prefabricated component surface can be restored, thereby improving its appearance quality.

[0078] Specifically, the alkali treatment method is to use a soft brush to remove the white sodium carbonate crystals on the surface, and then spray 0.5% polyacrylate emulsion (solid content 30%) to form a hydrophobic film to prevent secondary migration of water (water absorption rate is reduced by 40%).

[0079] In addition, after carbonization curing, geopolymer concrete enters the subsequent natural curing stage. Through humidity control and time effect under normal temperature environment, the internal areas where carbonization has not completely reacted are prompted to continue to undergo secondary gelation reaction and carbonate crystal growth, ultimately achieving microstructural stability, continuous strength growth and improved durability.

[0080] Specifically, the natural curing stage includes the following steps: 1) Continuous utilization of unreacted active ingredients A. Condensation of residual silica-alumina gel: After carbonization and curing, 20%–30% of unreacted amorphous aluminum-silicon phase remains in the slurry, such as an incompletely depolymerized network. In the natural curing environment of room temperature and humidity, the condensation reaction continues under alkaline conditions to form a denser three-dimensional polymer gel, thereby improving the structural continuity (the gel porosity drops from 25% after carbonization to below 20%).

[0081] B. Secondary crystallization of carbonates: The bicarbonate generated by carbonization slowly transforms into calcium carbonate / sodium carbonate crystals (particle size grows from 50nm to 200nm) during humidity fluctuations, filling the gel pores and enhancing the interfacial adhesion (interface strength increases by 15%–20%).

[0082] 2) Material migration driven by humidity gradient During the initial natural curing period (1–3 days), the high humidity (moisture content 10%–15%) inside the component promotes the migration of free Na⁺ and Al³⁺ ions to the carbonized layer, where they react with residual CO₂ to form additional carbonates, achieving a synergistic effect of “surface strengthening + internal supplementary reaction”. In the later stage (after 7 days), as the humidity drops, water slowly evaporates from the inside to the surface, carrying unreacted silica-alumina colloid to deposit in the pores, forming a self-healing gelling film (thickness 1–2 μm), blocking harmful pores (pores with a pore size > 50 nm are reduced by 30%).

[0083] 3) Maintenance site planning Zoning management: Divided into a transition zone (1–3 days) and a stable zone (more than 4 days). The transition zone is equipped with a spray system (atomized particles ≤ 50 μm) and a temperature and humidity recorder (accuracy ±2% RH, ±1°C). The stable zone uses a movable sunshade to adjust the light; Stacking method: Thin-walled components (wall panels): placed vertically on steel shelves (tilted 10° to prevent tipping), with rubber pads (2cm thick to reduce contact stress) used to isolate layers; Thick and large components (foundation blocks): stack horizontally, raise the bottom layer by 15 cm to prevent moisture, and separate each layer with wooden planks (30 cm apart to ensure ventilation at the bottom).

[0084] Intelligent monitoring system: IoT sensors are installed in each maintenance area to upload temperature and humidity data to the central control room in real time. When the humidity is <50% or >75%, an alarm is automatically triggered (response time ≤5 minutes); 1% of the components are sampled every week for rebound hammer strength testing, and a "curing time-strength growth" curve is established. If the strength growth of a batch within 3 days is <10%, the parameters of the carbonization curing stage are traced to see if they are abnormal.

[0085] Lifting and shipping Compared with ordinary concrete precast components, the characteristics of geopolymer concrete, such as "highly brittle carbonized layer + relatively weak interface bonding", result in much higher requirements for stress dispersion, surface protection and environmental control during lifting and transportation than ordinary concrete.

[0086] Precast geopolymer concrete components require moisture protection during long-distance transportation (humidity < 60%) to prevent the carbonized layer from absorbing moisture, which can cause the surface to turn white. This is because the carbonized layer of geopolymer contains soluble carbonates, which easily precipitate white frost after absorbing moisture. During high-temperature transportation, shade is required (surface temperature < 45°C) to prevent the carbonized layer from overheating and cracking. Insulation is required at low temperatures (temperature > 0°C). This is because the carbonized layer of geopolymer has a higher coefficient of thermal expansion than ordinary concrete, resulting in more significant thermal stress. Finally, components that have reached their designed strength are transported by trailer to the project site for hoisting and installation.

[0087] Compared with the prior art, the present invention has the following advantages: The present invention activates and utilizes construction waste, reducing the high-energy consumption of cement products. At the same time, the high-temperature flue gas can be reused for carbonization curing. At the same time, based on the principle of stepped carbonization equalization, carbon dioxide can be reused multiple times to achieve self-sufficiency in carbon emissions and carbon utilization, reducing external emissions, improving product quality, increasing resource utilization, reducing carbon emissions, optimizing production processes and reducing costs. It realizes the combination of traditional cement plants, concrete mixing plants and prefabricated component plants, and provides an integrated transformation plan for geopolymer concrete carbonization production. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1 This is a schematic diagram of the integrated system for carbonization production of geopolymer concrete based on the step-by-step carbonization principle of the present invention.

[0089] Figure 2 FIG. 1 is a schematic diagram of an embodiment of a carbonization curing chamber of the present invention.

[0090] Figure 3 FIG. 1 is a schematic diagram of an embodiment of a carbonization curing chamber of the present invention.

[0091] Figure 4 FIG. 1 is a schematic diagram of an embodiment of a carbonization curing chamber of the present invention.

[0092] Figure 5 FIG. 1 is a schematic diagram of an embodiment of a carbonization curing chamber of the present invention. DETAILED DESCRIPTION

[0093] In order to make those skilled in the art more clearly understand the technical solutions of the present invention, the following examples are given 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.

[0094] The present invention will be further described below in conjunction with specific embodiments: like Figure 1 As shown, the integrated system for carbonization production of geopolymer concrete based on the step-by-step carbonization principle includes the following steps: S1. Soil excavated from the project is used as raw material, which is dried in a three-pass drum dryer. The soil is then screened using a mobile sand washing machine to produce powder, aggregate, and other types of soil. The powder and cement raw meal are then calcined in a high-temperature rotary kiln. The calcined flue gas is then injected into a flue gas storage tank, while the powder, aggregate, and other types of soil are transferred to a storage tank. The processed powder is loaded into the slag powder storage tank, and other types of slag are loaded into the fine aggregate storage tank, coarse aggregate storage tank and other tanks after screening. The other tanks are used to store crushed stone particles. The fine aggregate storage tank is used to store aggregates with a particle size of 1.2-4.75mm, and the coarse aggregate storage tank is used to store aggregates with a particle size of 4.75-20mm. The powder particle size is less than 1.2mm, and the crushed stone particle size is greater than 20mm. The drying temperature in step S1 is 100-110°C for 24 hours, and the calcination temperature includes a low-temperature stage of 300-500°C, a dehydration stage of 500-700°C, and a calcination stage of 700°C; S2. The powder and aggregate from step S1 are mixed with the liquid, admixture, and admixture in a forced mixing chamber to obtain geopolymer concrete. The geopolymer concrete is weighed and mixed according to a proportion, and quantitatively distributed into the component mold by a distribution machine. The geopolymer concrete is then vibrated and compacted by a distribution turnover platform. The precast component obtained by the geopolymer concrete is sent to a pre-curing room for pre-curing. The pre-curing in step S2 adopts a constant temperature and humidity environment with a temperature controlled at 20-25° C. and a humidity maintained at above 95% for 24 hours. S3, the calcined flue gas in step S1 is sent to the dust collector for dust removal after cooling down the high-temperature decomposition gas through the heat exchanger, and then sent to the desulfurization bed, drying bed, and precision adsorption bed for desulfurization, drying, dust removal and removal of nitrogen oxides, and finally sent to the flue gas storage tank; the carbon dioxide replenishment device includes a carbon dioxide tanker and an electric heating vaporizer, the carbon dioxide tanker is equipped with a low-temperature liquid CO2 storage tank, the electric heating vaporizer has a power of 50kW and controls the heating rate at 0.5-1.0m 3 / min; the calcination flue gas of step S1 and the carbon dioxide supplement device form a gas source device, and the prefabricated components pre-cured in step S2 are sent to a carbonization curing chamber having multiple series-connected kettles through an assembly line, and the gas source devices are respectively connected to each kettle, and the residual gas of the previous kettle is transferred to the next kettle by equalizing the pressure, forming a gas concentration gradient between the kettles, and the gas source device supplements the gas concentration of each kettle; the prefabricated components are cured separately in the series-connected kettles arranged along the steps, and the number of kettles is at least four, and the residual gas of the last kettle is discharged to the outside or connected to the flue gas storage tank, the carbon dioxide tanker, or the gas source device; S4. The prefabricated components that have undergone carbonization curing in step S3 enter the natural curing stage. Step S4 also includes repairing carbonized layer defects and efflorescence treatment. The prefabricated components that have reached the designed strength are transported to the project site for hoisting and installation.

[0095] Calculated by mass, the geopolymer concrete includes 100-150 parts of heat-activated slag soil mixture, 500-600 parts of aggregate, 1000-1200 parts of crushed stone particles, 230-250 parts of water, 45-60 parts of admixture, and 30-60 parts of admixture.

[0096] Admixtures include alkali activators, retarders, air entraining agents, and water reducers. Alkaline activators include sodium hydroxide and water glass. Retarder includes sodium carboxymethyl cellulose and sodium gluconate. Air entraining agents include modified rosin acid soap and BASF's Disponil A3065 non-ionic linear fatty alcohol polyoxyethylene ether mixture. Water reducers include one or more of naphthalenesulfonic acid formaldehyde condensate and polycarboxylic acid water reducers with a main chain composed of a copolymer of methacrylic acid and methyl acrylate and a side chain of polyoxyethylene. Naphthalenesulfonic acid formaldehyde condensate adopts Shuer's whshuer dispersant CNF.

[0097] Admixtures include silica fume and modified slag powder.

[0098] The mass ratio of the thermally activated slag mixture to the alkali activator is 1:0.05-0.2; The heat-activated slag mixture is specifically mixed with powder and cement raw material, wherein the mass ratio of powder to cement raw material is 4:6, and the cement raw material is composed of limestone, clay and steel slag; The mass ratio of fine aggregate to coarse aggregate in the aggregate is 1:2; Preparation method of modified slag powder: M1. Mix S95 grade slag powder and ultrafine steel slag powder evenly, and grind the slag in a ball mill for 2 hours; Calculated by mass, 70 parts of S95 grade slag powder and 20 parts of ultrafine steel slag powder.

[0099] M2. Evenly mix the ground slag powder with hemihydrate gypsum; add triethanolamine and grind the slag in a ball mill for 4 hours. The grinding specific surface area is 520m² / kg.

[0100] Preparation method of modified rosin acid soap: N1. Add rosin acid, anhydrous zinc chloride and sulfuric acid to 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 the rosin acid, the amount of sulfuric acid used is 0.5% of the mass of the rosin acid, and the stirring speed is 150 rpm.

[0101] 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 the dimerized rosin acid to form dimerized rosin acid soap, the molar ratio of dimerized rosin to sodium hydroxide is 1:2, and the stirring speed is 200 rpm.

[0102] N3. Separate the dimerized rosin acid soap from unreacted alkali and impurities by centrifugation. Wash the dimerized rosin acid soap three times with hot water at 70°C to remove residual alkali and impurities. Dry the washed dimerized rosin acid soap in a vacuum drying oven at 70°C for 6 hours to reduce the moisture content to below 3%. The dried product can be crushed in a grinder and sieved to obtain a 100-mesh dimerized rosin acid soap product.

[0103] Preparation method of a polycarboxylic acid water reducer with a main chain composed of a copolymer of methacrylic acid and methyl acrylate and a side chain composed of polyoxyethylene: P1. At 80°C, methacrylic acid, methyl acrylate, ammonium persulfate and thioglycolic acid were 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 water reducer product.

[0104] Specifically, the molecular weight of methoxy polyethylene glycol methacrylate is 3000, and its purity is greater than 95%. The methoxy polyethylene glycol methacrylate is mixed with water to obtain a 50% by weight solution. 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 used is 2% of the total weight of the methacrylic acid and methyl acrylate, and the amount of thioglycolic acid used is 0.5% of the total weight of the methacrylic acid and methyl acrylate.

[0105] 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.

[0106] The preparation of geopolymer concrete includes the following steps: T1: Place the mixture of coarse and fine aggregates and activated soil into a mixer and dry mix for 60-90 seconds at a medium speed (80-120 r / min). The purpose is to evenly cover the aggregate surface with cementitious material, disperse cementitious material agglomerates, and avoid segregation of wet-mixed aggregates and the formation of dry powder balls that are difficult to disperse. T2: Premix the activator, admixtures, and additives + wet mix: Dissolve solid NaOH in one-third water in advance. After cooling, mix with water glass in a mass ratio of 2:8 and stir thoroughly. Pour the premixed activator solution, admixtures, and additives into a blender at a uniform speed. Stir at a low speed (50-80 rpm) for 120-180 seconds to ensure that the aggregate and cementitious material are fully wetted. Stir until no dry powder particles are visible and the aggregate surface is completely coated with the paste.

[0107] T3: Adjustment and Homogenization: Add the crushed stone particles to the mixer. Add the remaining water according to the established mix ratio and the fluidity. After all the water is added, mix at high speed (150-200 rpm) for 30 seconds to quickly improve the homogenization. Then, mix at low speed (50-80 rpm). The total wet mixing time should not exceed 5 minutes to avoid premature hydration and excessive coagulation.

[0108] Example 1 The geopolymer concrete includes 100 parts of heat-activated slag soil mixture, 500 parts of aggregate, 1000 parts of crushed stone particles, 230 parts of water, 45 parts of admixture, and 30 parts of admixture.

[0109] The admixtures include 20 parts of alkali activator, 10 parts of retarder, 10 parts of air entraining agent, and 5 parts of water reducer. The alkali activator includes sodium hydroxide and water glass, the retarder is sodium carboxymethyl cellulose, the air entraining agent is BASF's Disponil A 3065 non-ionic linear fatty alcohol polyoxyethylene ether mixture, and the water reducer is Shuer's whshuer dispersant CNF.

[0110] The admixture includes 15 parts of silica fume and 15 parts of modified slag powder.

[0111] The heat-activated slag mixture is specifically mixed with powder and cement raw material, wherein the mass ratio of powder to cement raw material is 4:6, and the cement raw material is composed of limestone, clay and steel slag; The mass ratio of fine aggregate to coarse aggregate in the aggregate is 1:2; like Figure 2 As shown, the prefabricated components manufactured in the above manner are transported along the assembly line into the carbonization curing chamber. First, the prefabricated components enter kettle 1, where the initial CO2 concentration is 20%. The CO2 concentrations in kettles 2, 3, and 4 are close to the CO2 concentration in air. Once kettle 1 is sealed, the CO2 preferentially reacts with the highly active sites on the component's surface, forming a dense carbonate shell. After two hours of reaction in kettle 1, the prefabricated components consume 8% of the CO2. In the second stage, the gas valve between kettle 1 and kettle 2 is opened, and the prefabricated component is transferred to kettle 2 along the assembly line. The residual gas after the reaction in kettle 1 is injected into kettle 2. At this time, kettle 1 and kettle 2 form an equal pressure, and the CO2 concentration in kettle 1 and kettle 2 is 6%. After 5 minutes of automatic balancing, the gas valve between kettle 1 and kettle 2 is closed, and new gas is added until the CO2 concentration in kettle 2 reaches 15%. After kettle 2 is sealed, the remaining CO2 diffuses into the middle layer of the component and reacts with the secondary active sites. At this time, the shell layer formed on the surface can guide the gas to penetrate into the interior to avoid "short circuit". The prefabricated component consumes 6% of the CO2 after 2 hours of reaction in kettle 2. In the third stage, the air valve between kettle 2 and kettle 3 is opened, and the prefabricated components are transferred to kettle 3 along the assembly line. The residual gas after the reaction in kettle 2 is injected into kettle 3. At this time, kettle 2 and kettle 3 form an equal pressure, and the CO2 concentration in kettle 2 and kettle 3 is 4.5%. After 5 minutes of automatic balancing, the air valve between kettle 2 and kettle 3 is closed, and a small amount of new air is added until the CO2 concentration in kettle 3 reaches 6%. After kettle 3 is sealed, the remaining CO2 diffuses to promote deep carbonization, ensuring sufficient internal reaction; the prefabricated components consume 4% of the CO2 after 3 hours of reaction in kettle 3; The prefabricated components that have passed the third stage can be directly transferred out of the carbonization curing room. The gas valve between kettle 3 and kettle 4 is opened, and part of the residual gas in kettle 3 is transferred to kettle 4. At this time, kettle 3 and kettle 4 form equal pressure, and the gas valve between kettle 3 and kettle 4 is closed. Kettle 4 collects 1% CO2 and discharges it directly.

[0112] At this point, the air source device supplies air to Kettle 1, with an initial CO2 concentration of 20% in Kettle 1, 4.5% in Kettle 2, 1% in Kettle 3, and close to the CO2 concentration in air in Kettle 4. The next batch of precast components follows the assembly line into the carbonization curing room, where carbonization curing continues according to the above steps.

[0113] Example 2 Calculated by mass, geopolymer concrete includes 150 parts of heat-activated slag soil mixture, 600 parts of aggregate, 1200 parts of crushed stone particles, 250 parts of water, 60 parts of admixture, and 60 parts of additives.

[0114] The admixtures include 30 parts of alkali activator, 15 parts of retarder, 5 parts of air entraining agent, and 10 parts of water reducer. The alkali activator includes sodium hydroxide and water glass, the retarder is sodium gluconate, the air entraining agent is modified rosin acid soap, and the water reducer is 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.

[0115] The admixture includes 40 parts of silica fume and 20 parts of modified slag powder.

[0116] The heat-activated slag mixture is specifically mixed with powder and cement raw material, wherein the mass ratio of powder to cement raw material is 4:6, and the cement raw material is composed of limestone, clay and steel slag; The mass ratio of fine aggregate to coarse aggregate in the aggregate is 1:2; like Figure 3 As shown, the prefabricated components manufactured in the above manner are transported along the assembly line into the carbonization curing chamber. First, the prefabricated components enter kettle 1, where the initial CO2 concentration is 20%. The CO2 concentrations in kettles 2, 3, 4, and 5 are close to the CO2 concentration in air. Once kettle 1 is sealed, the CO2 preferentially reacts with the highly active sites on the component's surface, forming a dense carbonate shell. After 1.5 hours of reaction in kettle 1, the prefabricated components consume 6% of the CO2. In the second stage, the gas valve between kettle 1 and kettle 2 is opened, and the prefabricated component is transferred to kettle 2 along the assembly line. The residual gas after the reaction in kettle 1 is injected into kettle 2. At this time, kettle 1 and kettle 2 form an equal pressure, and the CO2 concentration in kettle 1 and kettle 2 is 7%. After 5 minutes of automatic balancing, the gas valve between kettle 1 and kettle 2 is closed, and a small amount of new gas is added until the CO2 concentration in kettle 2 reaches 14%. After kettle 2 is sealed, the remaining CO2 diffuses into the middle layer of the component and reacts with the secondary active sites. At this time, the shell layer formed on the surface can guide the gas to penetrate into the interior, avoiding "short circuit"; the prefabricated component consumes 5% of the CO2 after 1.5 hours of reaction in kettle 2; In the third stage, the gas valve between kettle 2 and kettle 3 is opened, and the prefabricated components are transferred to kettle 3 along the assembly line. The residual gas after the reaction in kettle 2 is injected into kettle 3. At this time, kettle 2 and kettle 3 form an equal pressure, and the CO2 concentration in kettle 2 and kettle 3 is 4.5%. After 5 minutes of automatic balancing, the gas valve between kettle 2 and kettle 3 is closed, and a small amount of new gas is added until the CO2 concentration in kettle 3 reaches 8%. After kettle 3 is sealed, the remaining CO2 diffuses to promote deep carbonization, ensuring sufficient internal reaction; the prefabricated components consume 4% of the CO2 after reacting in kettle 3 for 1.5 hours; In the fourth stage, the air valve between kettles 3 and 4 is opened, and the prefabricated components are transferred to kettle 4 along the assembly line. The residual gas after the reaction in kettle 3 is injected into kettle 4. At this time, kettles 3 and 4 form an equal pressure, and the CO2 concentration in kettles 3 and 4 is 2%. After 5 minutes of automatic balancing, the air valve between kettles 3 and 4 is closed, and a small amount of new air is added until the CO2 concentration in kettle 3 reaches 5%. After kettle 4 is sealed, the remaining CO2 diffuses to promote deep carbonization, ensuring sufficient internal reaction; the prefabricated components consume 3% of the CO2 after reacting in kettle 4 for 2.5 hours; The prefabricated components that have passed the fourth stage can be directly transferred out of the carbonization curing room. The gas valve between kettle 4 and kettle 5 is opened, and part of the residual gas in kettle 4 is transferred to kettle 5. At this time, kettle 4 and kettle 5 form equal pressure, and the gas valve between kettle 4 and kettle 5 is closed. The 1% CO2 collected in kettle 4 is converted into liquid through the condensation recovery device and transferred to the carbon dioxide tanker.

[0117] At this point, the gas source device supplies air to Kettle 1, with an initial CO2 concentration of 20% in Kettle 1, 7% in Kettle 2, 4.5% in Kettle 3, and 1% in Kettle 4. Kettle 5 is close to the CO2 concentration in air. The next batch of precast components follows the assembly line into the carbonization curing room, where carbonization curing continues according to the above steps.

[0118] Example 3 Calculated by mass, geopolymer concrete includes 150 parts of heat-activated slag soil mixture, 550 parts of aggregate, 1,100 parts of crushed stone particles, 240 parts of water, 47.5 parts of admixtures, and 40 parts of additives.

[0119] The admixtures include 7.5 parts of alkali activator, 15 parts of retarder, 10 parts of air entraining agent, and 15 parts of water reducer. The alkali activator includes sodium hydroxide and water glass, the retarder is sodium carboxymethyl cellulose, the air entraining agent is modified rosin acid soap, and the water reducer is Shuer's whshuer dispersant CNF.

[0120] The admixture includes 20 parts of silica fume and 20 parts of modified slag powder.

[0121] The heat-activated slag mixture is specifically mixed with powder and cement raw material, wherein the mass ratio of powder to cement raw material is 4:6, and the cement raw material is composed of limestone, clay and steel slag; The mass ratio of fine aggregate to coarse aggregate in the aggregate is 1:2; like Figure 4 As shown, the prefabricated components manufactured in the above manner are transported along the assembly line into the carbonization curing chamber. First, the prefabricated components enter kettle 1, where the initial CO2 concentration is 20%. The CO2 concentrations in kettles 2, 3, 4, and 5 are close to the CO2 concentration in air. Once kettle 1 is sealed, the CO2 preferentially reacts with the highly active sites on the component's surface, forming a dense carbonate shell. After 1.5 hours of reaction in kettle 1, the prefabricated components consume 2% of the CO2. In the second stage, the gas valve between kettle 1 and kettle 2 is opened, and the prefabricated component is transferred to kettle 2 along the assembly line. The residual gas after the reaction in kettle 1 is injected into kettle 2. At this time, kettle 1 and kettle 2 form an equal pressure, and the CO2 concentration in kettle 1 and kettle 2 is 9%. After 5 minutes of automatic balancing, the gas valve between kettle 1 and kettle 2 is closed, and a small amount of new gas is added until the CO2 concentration in kettle 2 reaches 15%. After kettle 2 is sealed, the remaining CO2 diffuses into the middle layer of the component and reacts with the secondary active sites. At this time, the shell layer formed on the surface can guide the gas to penetrate into the interior to avoid "short circuit"; the prefabricated component consumes 2% of CO2 after 2 hours of reaction in kettle 2; In the third stage, the air valve between kettle 2 and kettle 3 is opened, and the prefabricated components are transferred to kettle 3 along the assembly line. The residual gas after the reaction in kettle 2 is injected into kettle 3. At this time, kettle 2 and kettle 3 form an equal pressure, and the CO2 concentration in kettle 2 and kettle 3 is 6.5%. The initial CO2 concentration in kettle 3 is maintained between 5-10% without adding carbon dioxide. After 5 minutes of automatic balancing, the air valve between kettle 2 and kettle 3 is closed. After kettle 3 is sealed, the remaining CO2 diffuses to promote deep carbonization, ensuring sufficient internal reaction. The prefabricated components consume 1.5% of the CO2 after 2 hours of reaction in kettle 3. In the fourth stage, the gas valve between kettle 3 and kettle 4 is opened, and the prefabricated component is transferred to kettle 4 along the assembly line. The residual gas after the reaction in kettle 3 is injected into kettle 4. At this time, kettle 3 and kettle 4 form equal pressure, and the CO2 concentration in kettle 3 and kettle 4 is 2.5%. After 5 minutes of automatic balance, the gas valve between kettle 3 and kettle 4 is closed, and a small amount of new gas is added until the CO2 concentration in kettle 4 is 3%, and the CO2 concentration in kettle 4 is maintained between 3-8%. When the initial CO2 concentration in kettle 4 is lower than 3%, carbon dioxide is added. After kettle 4 is in a closed state, the remaining CO2 diffuses to promote deep carbonization, ensuring sufficient internal reaction; the prefabricated component consumes 0.5% of CO2 after reacting in kettle 4 for 1.5 hours; The prefabricated components that have passed the fourth stage can be directly transferred out of the carbonization curing room. The gas valve between kettle 4 and kettle 5 is opened, and part of the residual gas in kettle 4 is transferred to kettle 5. At this time, kettle 4 and kettle 5 form equal pressure, and the gas valve between kettle 4 and kettle 5 is closed. Kettle 5 collects 1.25% CO2 and transfers it to the flue gas storage tank.

[0122] At this point, the gas source device supplies air to Kettle 1, with an initial CO2 concentration of 20% in Kettle 1, 6.5% in Kettle 2, 2.5% in Kettle 3, and 1.25% in Kettle 4. Kettle 5 is close to the CO2 concentration in air. The next batch of precast components follows the assembly line into the carbonization curing room, where carbonization curing continues according to the above steps.

[0123] Example 4 Calculated by mass, geopolymer concrete includes 120 parts of heat-activated slag soil mixture, 600 parts of aggregate, 1200 parts of crushed stone particles, 250 parts of water, 50 parts of admixture, and 50 parts of additives.

[0124] The admixtures include 12 parts of alkali activator, 15 parts of retarder, 11 parts of air entraining agent, and 12 parts of water reducer. The alkali activator includes sodium hydroxide and water glass. The retarder is 10 parts of sodium carboxymethyl cellulose and 5 parts of sodium gluconate. The air entraining agent is 5 parts of modified rosin acid soap and 6 parts of BASF's Disponil A 3065 non-ionic linear fatty alcohol polyoxyethylene ether mixture. The water reducer is 5 parts of Shuer's whshuer dispersant CNF and 7 parts of a polycarboxylic acid-based water reducer with a main chain composed of a copolymer of methacrylic acid and methyl acrylate and a side chain of polyoxyethylene. The admixture includes 20 parts of silica fume and 30 parts of modified slag powder.

[0125] The heat-activated slag mixture is specifically mixed with powder and cement raw material, wherein the mass ratio of powder to cement raw material is 4:6, and the cement raw material is composed of limestone, clay and steel slag; The mass ratio of fine aggregate to coarse aggregate in the aggregate is 1:2; like Figure 5As shown, the prefabricated components manufactured in the above manner are transported along the assembly line into the carbonization curing chamber. First, the prefabricated components enter kettle 1, where the initial CO2 concentration is 20%. The CO2 concentrations in kettles 2, 3, and 4 are close to the CO2 concentration in air. Once kettle 1 is sealed, the CO2 preferentially reacts with the highly active sites on the component's surface, forming a dense carbonate shell. After two hours of reaction in kettle 1, the prefabricated components consume 8% of the CO2. In the second stage, the gas valve between kettle 1 and kettle 2 is opened, and the prefabricated component is transferred to kettle 2 along the assembly line. The residual gas after the reaction in kettle 1 is injected into kettle 2. At this time, kettle 1 and kettle 2 form an equal pressure, and the CO2 concentration in kettle 1 and kettle 2 is 6%. After 5 minutes of automatic balancing, the gas valve between kettle 1 and kettle 2 is closed, and a small amount of new gas is added until the CO2 concentration in kettle 2 reaches 15%. After kettle 2 is sealed, the remaining CO2 diffuses into the middle layer of the component and reacts with the secondary active sites. At this time, the shell layer formed on the surface can guide the gas to penetrate into the interior to avoid "short circuit". The prefabricated component consumes 4% of CO2 after 2 hours of reaction in kettle 2. In the third stage, the gas valve between kettle 2 and kettle 3 is opened, and the prefabricated components are transferred to kettle 3 along the assembly line. The residual gas after the reaction in kettle 2 is injected into kettle 3. At this time, kettle 2 and kettle 3 form equal pressure, and the CO2 concentration in kettle 2 and kettle 3 is 5.5%. After 5 minutes of automatic balancing, the CO2 concentration in kettle 3 is maintained between 3-8%. When the initial CO2 concentration in kettle 3 is lower than 3%, carbon dioxide is replenished. The gas valve between kettle 2 and kettle 3 is closed. After kettle 3 is sealed, the remaining CO2 diffuses to promote deep carbonization, ensuring sufficient internal reaction. The prefabricated components consume 2% of CO2 after 3 hours of reaction in kettle 3. The prefabricated components that have passed the third stage can be directly transferred out of the carbonization curing room. The gas valve between kettle 3 and kettle 4 is opened, and part of the residual gas in kettle 3 is transferred to kettle 4. At this time, kettle 3 and kettle 4 form equal pressure, and the gas valve between kettle 3 and kettle 4 is closed. Kettle 4 collects 1.75% CO2 and transfers it to the gas source device.

[0126] At this point, the air source device supplies air to Kettle 1, with an initial CO2 concentration of 20% in Kettle 1, 5.5% in Kettle 2, 1.75% in Kettle 3, and close to the CO2 concentration in air in Kettle 4. The next batch of precast components follows the assembly line into the carbonization curing room, where carbonization curing continues according to the above steps.

[0127] Comparative Example 1 Compared with Example 1, the prefabricated components prepared in Example 1 were cured in the same kettle for 7 hours, and the carbon dioxide concentration of the input gas source was maintained at 15-20%. When the carbon dioxide concentration in the kettle was <15% and the pressure was <105 kPa, carbon dioxide was continuously added to the kettle. After 7 hours, the prefabricated components were transferred, and the kettle discharged the remaining 15% of CO2 to the outside.

[0128] Comparative Example 2 Compared with Example 2, the initial concentration of carbon dioxide in the air source input to the prefabricated components in the same kettle was 20%. After curing for 7 hours without adding carbon dioxide, the initial concentration of carbon dioxide decreased from 20% to below 10%. The prefabricated components successfully completed the 7-hour curing, and the kettle discharged the remaining 3% of CO2 to the carbon dioxide tanker.

[0129] Comparative Example 3 Compared with Example 3, the initial concentration of carbon dioxide in the prefabricated component's input gas source in the same kettle body is 20%. The same kettle body is continuously monitored, and it is necessary to discharge 3% of carbon dioxide to 15% to the flue gas storage tank or the outside world after 1.5 hours, and discharge 6.5% of carbon dioxide to the flue gas storage tank or the outside world after 2 hours of full reaction, and discharge 1.5% of carbon dioxide to the flue gas storage tank or the outside world after 2 hours of full reaction, and discharge 1.25% of carbon dioxide to the flue gas storage tank after 2 hours of full reaction.

[0130] Comparative Example 4 Compared with Example 4, the initial concentration of carbon dioxide in the gas source input to the prefabricated component in the same kettle is 20%. The same kettle is continuously monitored and it is necessary to add 3% of carbon dioxide to 15% after 2 hours. After 2 hours of full reaction, 5.5% of carbon dioxide is discharged to the gas source device or the outside world. After 3 hours of full reaction, 3.5% of carbon dioxide is discharged to the gas source device.

[0131] Compressive strength and flexural strength tests were carried out in accordance with GB / T50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete". The mechanical property test data of the prefabricated components of Examples 1-4 and Comparative Examples 1-4 are shown in Tables 1 and 2: Table 1: Performance test results of Examples 1-4

[0132] Table 2: Performance test results of comparative examples 1-4

[0133] The present invention provides a plurality of kettle bodies. In the initial stage of the reaction, the valve bodies of two adjacent kettle bodies are opened. After the adjacent kettle bodies are pressure-equalized, the concentration of the latter kettle body will be lower than the expected concentration. Without emitting carbon dioxide and causing waste, the workpiece is transferred to the next kettle body through the assembly line. The valve bodies of the two adjacent kettle bodies are closed, and the kettle bodies form a sealed space. The carbon dioxide concentration in the kettle body is replenished or not, and then the reaction is continued. In the later stage of the reaction, the valve bodies of the two adjacent kettle bodies are opened. After the adjacent kettle bodies are pressure-equalized, the concentration of the latter kettle body is close to the expected concentration. Without emitting carbon dioxide and causing waste, the workpiece is transferred to the next kettle body through the assembly line. The carbon dioxide concentration in the kettle body is replenished or not. The valve bodies of the two adjacent kettle bodies are closed, and the kettle bodies form a sealed space, and then the reaction is continued.

[0134] Through the initial 15%-20% rapid reaction of carbon dioxide, the mid-term stable penetration of 10%-15% carbon dioxide, and the late 5%-10% deep carbonization of carbon dioxide, the "shell effect" can be avoided, making the carbonization depth of prefabricated components more uniform, with better compressive strength and durability, and a low risk of microcracks.

[0135] In Examples 1-4, during the carbonization curing process, the prefabricated components produced do not require carbon dioxide emissions at any stage of the reaction. In multiple series-connected kettles, the residual gas from the preceding kettle is transferred to the succeeding kettle, forming a gas concentration gradient between the kettles. When the gas concentration in a kettle is insufficient, the gas source device replenishes the concentration in the kettle. The residual gas from the last kettle is discharged externally or connected to the gas source device, a flue gas storage tank, or a carbon dioxide tanker. The concentration of the residual gas discharged from the last kettle is less than 2%.

[0136] In Examples 1-4, the prefabricated components react in a concentration gradient during the carbonization curing process. The reaction process first reacts from the high-activity sites on the surface of the prefabricated components, then diffuses to the middle layer of the prefabricated components, and finally extends into the inner layer of the prefabricated components. This prevents the surface of the prefabricated components from carbonizing too quickly, hindering internal reactions and resulting in insufficient carbonization depth. It also reduces the waste of CO2 caused by the decreased utilization rate in the later stage of the reaction, avoids the concentration of reaction heat, and thus exacerbates temperature stress. The compressive strength and flexural strength of the prefabricated components made of the geopolymer concrete in Examples 1-4 can meet the mechanical strength requirements of the construction project, and can also meet the requirements of green environmental protection and reduced carbon dioxide emissions.

[0137] Furthermore, Examples 1-4 of the present invention reduce high-energy consumption cement products through the activation and utilization of construction waste, and the high-temperature flue gas can be reused for carbonization curing. At the same time, based on the principle of stepped carbonization equalization, carbon dioxide can be utilized multiple times to achieve self-sufficiency in carbon emissions and carbon utilization, reduce external emissions, improve product quality, increase resource utilization, reduce carbon emissions, optimize production processes and reduce costs, realize the combination of traditional cement plants, concrete mixing plants and prefabricated component plants, and provide an integrated transformation plan for geopolymer concrete carbonization production.

[0138] Furthermore, the geopolymer concrete components used in Examples 1-4 of the present invention can maintain good mechanical properties under various conditions: carbon dioxide consumption is in line with expectations, carbon dioxide consumption is higher than expectations, and carbon dioxide consumption is lower than expectations. Moreover, when the number of carbon dioxide emissions or transfers is only once, the total amount of carbon dioxide emitted or transferred can be kept below 10% of the initial total amount of carbon dioxide in the kettle 1, effectively reducing the waste of carbon dioxide.

[0139] In Comparative Example 1, the prefabricated component is cured in the same kettle for 7 hours, and the carbon dioxide of the input gas source is maintained at a concentration of 15-20%. The surface layer of the prefabricated component will carbonize too quickly, hindering the internal reaction, resulting in insufficient carbonization depth, CO2 waste caused by the decline in utilization rate in the later stage of the reaction, and concentrated reaction exothermic heat, thereby exacerbating temperature stress. Relative to Example 1, Example 1 reacts rapidly by 15%-20% carbon dioxide in the initial stage, stably penetrates 10%-15% carbon dioxide in the mid-term, and deeply carbonizes 5%-10% carbon dioxide in the later stage, which can avoid the "shell effect", making the carbonization depth of the prefabricated component more uniform, with better compressive strength and durability, and low risk of microcracks. Therefore, the mechanical strength of the prefabricated component of Example 1 is higher than that of Comparative Example 1, and Example 1 finally discharges 1% carbon dioxide, which is lower than the 15% carbon dioxide discharged by Comparative Example 1.

[0140] In Comparative Example 2, under ideal conditions, the initial CO2 concentration in the same kettle body decreased from 20% to below 10% over the course of 7 hours without the addition of CO2. The prefabricated components successfully completed the 7-hour curing period, and the mechanical properties of Comparative Example 2 were comparable to those of Example 2. In Example 2, 1% of the CO2 collected by kettle 4 was converted into liquid by the condensation recovery device and transferred to a CO2 tanker. In Comparative Example 2, the kettle body discharged the remaining 3% CO2 to the CO2 tanker. During the subsequent preparation process of Example 2, kettle 1 was supplemented with 13% CO2, resulting in an initial CO2 concentration of 20%. Kettle 2 had a CO2 concentration of 7%, kettle 3 had a CO2 concentration of 4.5%, kettle 4 had a CO2 concentration of 1%, and kettle 5 had a CO2 concentration close to the CO2 concentration in air. According to calculations based on Example 2, during the subsequent continuous reaction process, the CO2 concentration required to be wasted in each batch of prefabricated components was far less than 3%. During the continuous production process, the overall gas supply of the gas source device can be reduced, and the energy consumed in the conversion process of the condensation recovery device can be reduced.

[0141] In Comparative Example 3, the same kettle body was continuously monitored, and the consumption rate of carbon dioxide was lower than expected. The emitted carbon dioxide was higher than the utilized carbon dioxide. It was necessary to emit part of the carbon dioxide to the flue gas storage tank or the outside world, or supplement part of the air for dilution, in the first stage, emit part of the carbon dioxide to the flue gas storage tank or the outside world, or supplement part of the air for dilution, in the second stage, emit part of the carbon dioxide to the flue gas storage tank or the outside world, or supplement part of the air for dilution, and in the third stage, emit part of the carbon dioxide to the flue gas storage tank or the outside world, or supplement part of the air for dilution. Overall, the mechanical strength of Comparative Example 3 is not much different from that of Example 3. Some of the unused carbon dioxide is directly wasted, and the pipeline needs to continuously replenish and emit carbon dioxide, which can easily lead to fatigue of the inner wall of the pipeline.

[0142] During the subsequent continuous preparation process of Example 3, 7.75% of CO2 was added to kettle 1, resulting in an initial CO2 concentration of 20%, a CO2 concentration of 6.5% in kettle 2, a CO2 concentration of 2.5% in kettle 3, and a CO2 concentration of 1.25% in kettle 4. This concentration in kettle 5 is close to the CO2 concentration in air. According to the calculations in Example 3, during the subsequent continuous reaction process, the concentration of CO2 wasted in each batch of prefabricated components is far less than 3%. This reduces the overall gas supply of the gas source device and the number of times carbon dioxide is transferred to the flue gas storage tank during the continuous production process.

[0143] In Comparative Example 4, the same kettle was continuously monitored, and the carbon dioxide consumption rate was higher than expected. New carbon dioxide was added after 2 hours, and carbon dioxide was discharged after 2 hours of full reaction. The gas was directly discharged after 3 hours of full reaction. Overall, the mechanical strength of Comparative Example 4 was not much different from that of Example 4. Some unused carbon dioxide was discharged to the gas source device, and the pipeline needed to continuously replenish and discharge carbon dioxide, which easily led to fatigue of the pipeline inner wall. The proportion of admixtures and additives used in Example 4 was higher than that in Example 1. Therefore, the mechanical properties of Example 4 were slightly higher than those of Example 1.

[0144] During the subsequent preparation process of Example 4, 14% CO2 was added to kettle 1, resulting in an initial CO2 concentration of 20%, a CO2 concentration of 5.5% in kettle 2, a CO2 concentration of 1.75% in kettle 3, and a CO2 concentration close to the CO2 concentration in air in kettle 4. According to the calculations in Example 4, during the subsequent continuous reaction process, the overall concentration of CO2 wasted in each batch of prefabricated components will be less than 3%. During the continuous production process, the overall gas supply volume of the gas source device can be reduced, and the number of times carbon dioxide is transferred to the gas source device can be reduced.

[0145] The above is a preferred embodiment of the present invention. Relevant personnel in this technical field can 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 scope of protection of the present invention.

Claims

1. The integrated system for carbonization production of geopolymer concrete based on the principle of step-by-step carbonization is characterized by: The following steps are involved: S1. Soil is taken from the project excavation as raw material, and the excavated soil is dried by drying equipment. The excavated soil is sieved to obtain powder, aggregate, and other types of excavated soil. The powder is heat-treated and calcined, and the calcined flue gas is injected into the flue gas storage tank. The powder, aggregate, and other types of excavated soil are then transferred to the storage tank; S2. Evenly mixing the powder and aggregate obtained in step S1 with the liquid, admixture, and additive to obtain geopolymer concrete. The precast components obtained from the geopolymer concrete are sent to a pre-curing room for pre-curing. S3. The flue gas storage tank in step S1 and the carbon dioxide replenishing device form a gas source device. The prefabricated components pre-cured in step S2 are sent to a carbonization curing chamber having multiple kettles connected in series. The gas source device is connected to each kettle respectively. The residual gas from the previous kettle is transferred to the next kettle, forming a gas concentration gradient between the kettles. The gas source device replenishes the gas concentration of each kettle. S4. The prefabricated components that have undergone carbonization curing in step S3 enter the natural curing stage. The prefabricated components that have reached the design strength are transported to the project site for hoisting and installation.

2. The integrated system for carbonization production of geopolymer concrete based on the step-by-step carbonization principle according to claim 1 is characterized by: Calculated by mass, the geopolymer concrete includes 100-150 parts of heat-activated slag soil mixture, 500-600 parts of aggregate, 1000-1200 parts of crushed stone particles, 230-250 parts of water, 45-60 parts of admixture, and 30-60 parts of admixture.

3. The integrated system for carbonization production of geopolymer concrete based on the step-by-step carbonization principle according to claim 1 is characterized in that: After screening, other types of slag are loaded into fine aggregate storage tanks, coarse aggregate storage tanks and other tanks respectively. Other tanks are used to store crushed stone particles, fine aggregate storage tanks are used to store aggregates with a particle size of 1.2-4.75mm, coarse aggregate storage tanks are used to store aggregates with a particle size of 4.75-20mm, and the powder particle size is less than 1.2mm.

4. The integrated system for carbonization production of geopolymer concrete based on the step-by-step carbonization principle according to claim 1 is characterized by: The drying temperature in step S1 is 100-110° C. for 24 consecutive hours, and the calcination temperature includes a low-temperature stage of 300-500° C., a dehydration stage of 500-700° C., and a calcination stage of 700-750° C.

5. The integrated system for carbonization production of geopolymer concrete based on the step-by-step carbonization principle according to claim 1 is characterized by: Geopolymer concrete is weighed and mixed according to the proportion, and is quantitatively distributed into the component mold by a distribution machine, and then vibrated and compacted by a distribution turnover platform.

6. The integrated system for carbonization production of geopolymer concrete based on the stepwise carbonization principle according to claim 1 is characterized by: The pre-curing in step S2 adopts a constant temperature and humidity environment, with the temperature controlled at 20-25°C and the humidity maintained at above 95%, and the curing time is 24 hours.

7. The integrated system for carbonization production of geopolymer concrete based on the step-by-step carbonization principle according to claim 1 is characterized by: The calcined flue gas in step S1 is sent to a dust collector for dust removal after being cooled by a heat exchanger to cool the high-temperature decomposition gas. The gas is then sent to a desulfurization bed, a drying bed, and a precision adsorption bed for desulfurization, drying, dust removal, and removal of nitrogen oxides. The flue gas is finally sent to a flue gas storage tank.

8. The integrated system for carbonization production of geopolymer concrete based on the step-by-step carbonization principle according to claim 1 is characterized in that: The carbon dioxide replenishment device includes a carbon dioxide tanker and an electric heating vaporizer. The carbon dioxide tanker is equipped with a low-temperature liquid CO2 storage tank. The electric heating vaporizer has a power of 50kW and controls the heating rate at 0.5-1.0m 3 / min.

9. The integrated system for carbonization production of geopolymer concrete based on the step-by-step carbonization principle according to claim 1 is characterized by: The prefabricated components are cured separately in series with kettle bodies arranged along the steps. The number of kettle bodies is at least four, and the residual gas of the last kettle body is discharged to the outside or connected to the gas source device.

10. The method for preparing an integrated geopolymer concrete carbonization production system based on the stepwise carbonization principle according to claim 1, characterized in that: Step S4 also includes carbonized layer defect repair and efflorescence treatment.

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