Negative carbon cementing material in-situ mineralization intelligent stirring system and preparation method thereof

Abstract

The invention discloses a negative carbon cementing material in-situ mineralization intelligent stirring system and a preparation method thereof. According to the invention, the kinetic barrier of mineralization reaction is broken through multi-field coupling, the gas-liquid mass transfer efficiency and the crystal structure of the product are optimized, and the cooperation of efficient carbon sequestration, mechanical property gain and stable construction performance of the cementing material is realized; the method is suitable for large-scale preparation of low-carbon building materials such as industrial grade negative carbon concrete, geopolymer mortar and high-volume recycled aggregate concrete. The energy field cooperation mechanism fundamentally breaks through the mass transfer bottleneck of a traditional carbon injection technology, CO2 is dispersed into a nanoscale stable gas-liquid interface through the micro-nano bubble technology, the gas-liquid contact area is greatly expanded, and CO2 can rapidly permeate into internal pores of high-viscosity slurry. The ultrasonic vibration continuously breaks a hydration passivation layer on the surface of the gelling particles to expose more active reaction sites, and the microwave energy field accelerates the ion migration rate through molecular thermal motion to form an efficient synergistic chain, so that the mineralization fixation efficiency of CO2 is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of low-carbon building materials, and particularly relates to an in-situ mineralization intelligent stirring system for a negative-carbon cementitious material and a preparation method thereof. BACKGROUND

[0002] As the most used artificial material, the carbon emission reduction and carbon utilization (CCUS) of the production process of concrete has become the core of technological innovation. The cement and concrete industry contributes about 8% of the global carbon dioxide emissions, and the in-situ mineralization technology of concrete is considered as one of the most potential decarbonization paths because it can permanently store CO2 and improve material performance.

[0003] However, the existing CO2 in-situ mineralization stirring technology in the prior art has three engineering bottlenecks: first, the mass transfer efficiency is extremely low, the traditional large-bubble carbon injection method is easy to quickly float out in the viscous slurry, the gas-liquid contact area is insufficient, and most patents do not clearly specify the bubble generation mechanism and size control method, resulting in a low gas utilization rate of only 10%-15%; second, the reaction is seriously passivated, the CaCO3 generated in the early stage forms a dense passivation layer on the surface of the cementitious particles, making the reaction change from chemical control to diffusion control, and the carbonation degree is difficult to break through 20%, and the existing technology generally does not clarify the micro mechanism and feasible technical path of breaking the passivation layer; third, the rheological property and performance regulation are missing, the carbonation exothermic and ion intensity mutation easily cause the slurry to be false-condensed and lose flowability, at the same time, most patents lack the design of multi-field coupling mechanism and do not consider the influence of crystal type regulation on material density, and the shielding interference problem of microwave and metal parts is not solved, resulting in poor technology landing and limited performance improvement. SUMMARY

[0004] The purpose of the present application is to solve the above-mentioned problems, and to provide an in-situ mineralization intelligent stirring system for a negative-carbon cementitious material and a preparation method thereof.

[0005] The technical solution adopted by the present application is as follows: an in-situ mineralization intelligent stirring system for a negative-carbon cementitious material, comprising: a resonant stirring host, a multi-field coupling generating device, an external circulation micro-nano bubble carbon injection system, a sensing and monitoring module, and a digital twin intelligent control terminal; The stirring paddle of the resonant stirring host is integrally connected with the ultrasonic vibration node of the multi-field coupling generating device; The microwave module of the multi-field coupling generating device is connected with the metal shielding shell of the resonant stirring host through a waveguide interface, and the microwave energy penetrates through the microwave transparent ceramic lining of the host to act on the internal space.

[0006] The external circulation micro-nano bubble carbon injection system is connected with the cylinder side wall of the resonant stirring host through a tangential re-injection nozzle.

[0007] The torque sensor of the sensing and monitoring module is installed on the stirring shaft of the resonant mixer, the infrared temperature sensor is installed on the outer wall of the cylinder of the resonant mixer, the laser particle size sensor is connected to the circulation pipeline of the external circulation micro-nano bubble carbon injection system, and the graphene conductivity sensor is set at the slurry sampling port of the resonant mixer.

[0008] The digital twin intelligent control terminal establishes bidirectional communication connections with the drive motor of the resonant stirring host, the power controller of the multi-field coupling device, the high-pressure pump frequency converter of the external circulation micro-nano bubble carbon injection system, and the data acquisition unit of the sensing and monitoring module via an industrial bus.

[0009] In a preferred embodiment, the resonant stirring host has a sandwich structure consisting of a metal shielded shell, a thermal insulation layer, and a microwave-safe transparent ceramic liner. The ceramic liner is made of 99% alumina ceramic or silicon nitride, with a dielectric loss tangent tanδ < 0.001, microwave transmittance ≥ 95%, and Mohs hardness ≥ 9.

[0010] The stirring shaft is made of non-magnetic stainless steel and features a quarter-wavelength microwave choke. The stirring blades integrate multi-point distributed ultrasonic vibration nodes, employing a bending vibration mode, and are distributed along the shaft at different heights and angles. Radial vibration mode is also supported.

[0011] The resonant stirring host provides a quantitative basis for the staged stirring speed control of the resonant stirring host, the energy field parameter matching of the multi-field coupling generator, and the bubble injection rhythm of the external circulation micro-nano bubble carbon injection system through the reaction kinetic equation. By establishing a correlation model between reaction rate and energy field intensity, it guides the coordinated operation of each module.

[0012] The kinetic equation for the multi-energy field synergistic in-situ mineralization reaction of negative carbon cementitious materials is as follows: ; In the formula: r is the mineralization reaction rate, in units of mol / (L·s); k is the apparent rate constant, with units of k. Its value is determined by the temperature of the slurry and the cementitious material system; The concentration of free calcium ions in the slurry is expressed in mol / L. The concentration of dissolved CO2 in the slurry is expressed in mol / L. The ultrasonic power density of the multi-field coupling generator is expressed in W / L. The microwave power density of the multi-field coupling generator is expressed in W / g. N represents the stirring speed of the resonant mixer, expressed in r / min. α represents the reaction order of calcium ion concentration, with a value ranging from 0.6 to 0.9; β is the reaction order for CO2 concentration, with a value ranging from 0.4 to 0.7; γ is the ultrasonic power response order, with a value ranging from 0.2 to 0.4; δ is the microwave power response order, with a value ranging from 0.1 to 0.3; ε represents the reaction order at which the stirring speed is increased, and its value ranges from 0.3 to 0.5.

[0013] In a preferred embodiment, the multi-field coupling generator includes a dual-frequency ultrasonic module and a selectable-frequency microwave module. The ultrasonic module supports dual-frequency switching between 20kHz±2kHz and 40kHz±2kHz, as well as reverberation sweep frequency, with a power density of 50-200W / L. The microwave module can select a frequency of 915MHz or 2.45GHz, supports pulsed and continuous output, has a power density of 0.5-2.0W / g, and a duty cycle of 30%-70% in pulsed mode.

[0014] In a preferred embodiment, the external circulation micro / nano bubble carbon injection system includes a high-pressure pump, a multi-stage tandem Venturi cyclone shear generator, and tangential reinjection nozzles. The system operating pressure is 0.2-0.6 MPa, and the high-pressure pump output pressure is 0.3-0.5 MPa. The throat diameters of the multi-stage Venturi tubes are 8 mm, 6 mm, and 4 mm respectively, with a cavitation number σ ≤ 0.8. The generated CO2 micro / nano bubbles have a particle size of 50-500 nm, an absolute Zeta potential ≥ 30 mV, and remain stable in the slurry for ≥ 10 minutes.

[0015] In the core quantification process of the multi-stage Venturi vortex shear generator, the dynamic viscosity and density of the slurry are first obtained through rheological testing based on the initial mix proportions and temperature parameters of the slurry. Secondly, for the series structure of the multi-stage Venturi, the contraction ratio, expansion angle, and inlet length of each stage throat are parametrically modeled. Fluid dynamics simulation is then used to model the velocity distribution and pressure field changes under different throat sizes. Subsequently, a correction term for the saturated vapor pressure of CO2 in the slurry is introduced, extending the traditional cavitation number formula into a corrected model applicable to a gas-liquid-solid three-phase system. By calculating the cavitation values ​​under different inlet fluid pressures and equivalent throat diameters, the occurrence threshold and intensity range of the cavitation effect are analyzed. When the cavitation number is in the optimal range of 0.3-0.7, the sudden pressure drop at the Venturi throat will trigger a violent cavitation bubble collapse effect. Combined with the disturbance effect of the swirling shear blades, the introduced CO2 gas can be sheared and broken into micro-nano bubbles with a diameter of 10-50 μm. If the cavitation number is too high (>0.7), the cavitation effect is insufficient, the bubble particle size is too large and it is easy to aggregate and float, and it cannot be stably dispersed in high viscosity slurry. If the cavitation number is too low (<0.3), excessive cavitation will lead to secondary breakage of solid particles in the slurry, increase system energy consumption and affect the mechanical properties of cementitious materials. By establishing a correlation database between cavitation number, bubble generation efficiency, and particle size distribution, a precise design of a multi-stage Venturi cyclone shear generator can be achieved: the first-stage throat uses a smaller contraction ratio (1:3) and a lower inlet pressure (0.2MPa) to control the cavitation number at approximately 0.6, prioritizing the initial shear dispersion of CO2 gas; the second-stage throat uses a larger contraction ratio (1:5) and a higher inlet pressure (0.4MPa) to control the cavitation number at approximately 0.4, further refining the bubble particle size to below 20μm; the third-stage throat uses a medium contraction ratio (1:4) and a gradually varying inlet pressure (0.2-0.3MPa) to control the cavitation number at approximately 0.5, maintaining the suspension stability of micro- and nano-bubbles in the slurry, ultimately ensuring that the CO2 mineralization and fixation efficiency is increased by more than 30% during carbon injection, while the bubble residence time in the slurry is extended to more than 120s.

[0016] The formula for the corrected cavitation number is: ; In the formula: σc represents the corrected cavitation number applicable to high-viscosity cementitious slurries; p is the fluid pressure at the Venturi inlet (Pa); p_v is the saturated vapor pressure (Pa) of CO2 in the gel slurry; ρ is the density of the cementitious paste (kg / m³) 3 ); v is the average fluid velocity (m / s) at the cross-section of the Venturi throat. μ is the dynamic viscosity of the gel slurry (Pa·s); d is the equivalent diameter of the Venturi throat (m); k is the swirl shear correction factor, with a value ranging from 0.2 to 0.5, determined by the tilt angle and number of swirl blades.

[0017] In a preferred embodiment, the sensing and monitoring module includes a graphene conductivity sensor, a torque sensor, an infrared temperature sensor, and a laser particle size sensor. Each sensor monitors the mineralization reaction rate, apparent viscosity, reaction temperature, and bubble particle size distribution, respectively. The module is equipped with a high-speed wireless transmission module with a sampling frequency ≥10Hz to ensure the timeliness and stability of data transmission.

[0018] In a preferred embodiment, the digital twin intelligent control terminal constructs a thermoacoustic-fluid multi-field coupled digital twin model to achieve phased adaptive control. The control parameters cover stirring speed, ultrasonic frequency, amplitude, microwave power mode, and bubble injection parameters. The terminal is equipped with emergency control logic: when the slurry torque growth slope > 0.05 N·m / s, it automatically reduces the microwave power by 30% and switches to ultrasonic dual-frequency reverberation; when the conductivity change rate < 0.01 S / (m·min), it increases the microwave power to 1.5–2.0 W / g. The phased control is divided into three periods: during the dispersion carbon injection period, mechanical stirring operates at high speed, the ultrasonic module is activated at 20 kHz, the external circulation micro-nano bubble system is started, and the microwave module is turned off; during the nucleation and mineralization period, mechanical stirring operates at medium speed, the ultrasonic module switches to 40 kHz or dual-frequency reverberation, and the microwave module operates in pulse mode; during the curing and densification period, mechanical stirring operates at low speed, the ultrasonic module is intermittently activated, and the microwave module operates continuously at low power. When the conductivity stabilizes, the energy field and bubble system are turned off. The emergency control logic of the digital twin intelligent control terminal is as follows: when the slope of the slurry torque growth is >0.05 N·m / s, the microwave power is automatically reduced by 30% and the ultrasonic dual-frequency reverberation is switched; when the conductivity change rate is <0.01 S / (m·min), the microwave power is increased to 1.5-2.0 W / g.

[0019] In a preferred embodiment, a method for preparing a carbon negative cementitious material includes the following steps: S1: Add cementitious materials, aggregates, and mixing water, start the resonant mixing host at high speed, and simultaneously start the external circulation micro-nano bubble carbon injection system. Inject CO2 micro-nano bubbles into the mixing tank through the tangential back injection nozzle. At the same time, turn on the 20kHz ultrasonic band of the multi-field coupling generator to break up the cementitious particle agglomerates and peel off the initial hydration film, providing a uniform reaction substrate for the subsequent nucleation and mineralization stage, and ensuring that CO2 can fully contact the cementitious particles in the subsequent steps.

[0020] S2: After completing the dispersion and carbon injection in stage S1, adjust the stirring speed of the resonant stirring host to medium speed, switch the ultrasonic frequency band of the multi-field coupling generator to 40kHz, and turn on the microwave module pulse mode to maintain the slurry temperature at 40-50℃. Based on the torque data fed back by the sensor monitoring module in stage S1, adjust the ultrasonic amplitude and microwave power in real time to ensure the stable progress of the mineralization reaction and lay the foundation for the crystal transformation in the subsequent curing and densification stage.

[0021] S3: After the mineralization reaction in stage S2 reaches a stable state, reduce the stirring speed of the resonant stirring host to a low speed, adjust the ultrasonic system to intermittent operation mode, switch the microwave module to continuous low power output, and at the same time shut down the external circulation micro-nano bubble carbon injection system. Combined with the conductivity data fed back by the sensing and monitoring module in stage S2, fine-tune the microwave power to promote the directional transformation of crystal form, optimize the pore structure of the material, and finally complete the preparation of the negative carbon cementitious material.

[0022] In a preferred embodiment, in step S1, when the cementitious material system contains recycled aggregate, a pretreatment step is added before stage one: the recycled aggregate and cement slurry accounting for 5%-15% of the total cementitious material are put into the mixing host, the ultrasonic module is turned on at a frequency of 40-45kHz, the power density is 150-200W / L, and the treatment time is 0.5-2 minutes.

[0023] In a preferred embodiment, in step S2, the pulse duty cycle of the microwave module is 30%-70%, and when the slurry torque is monitored to be ≥80 N·m, the microwave power is reduced by 20%-40%, and the ultrasound is switched to dual-frequency reverberation mode.

[0024] In a preferred embodiment, in step S3, the micro-nano bubble system operates continuously in stages one to two and is shut down in stage three, with the bubble injection volume to cementitious material mass ratio being 0.05-0.1:1.

[0025] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. In this invention, the energy field synergy mechanism fundamentally breaks through the mass transfer bottleneck of traditional carbon injection technology. Micro-nano bubble technology disperses CO2 into a stable gas-liquid interface at the nanoscale, greatly expanding the gas-liquid contact area and allowing CO2 to quickly penetrate into the internal pores of high-viscosity slurry. Ultrasonic vibration continuously breaks down the hydration passivation layer on the surface of the gel particles, exposing more active reaction sites, while the microwave energy field accelerates ion migration rates through molecular thermal motion, forming a highly efficient synergistic chain. This results in an order-of-magnitude increase in CO2 mineralization and fixation efficiency, truly achieving the goal of negative carbon in industrial production.

[0026] 2. In this invention, crystal form orientation control technology plays a crucial role in the mineralization process. Early-formed aragonite crystals are uniformly dispersed in the slurry at the nanoscale, providing ample nucleation sites for subsequent crystal form transformation. As the reaction progresses, the aragonite gradually transforms into calcite crystals. This transformation, accompanied by volume expansion, precisely fills the capillary pores within the slurry, optimizing the material's pore structure at the microscopic level. Simultaneously, the calcium carbonate crystals generated by the mineralization reaction form tight chemical bonds with the cementitious matrix, significantly improving the material's density. This not only leads to rapid early strength growth but also fundamentally improves long-term durability properties such as resistance to chloride ion penetration and freeze-thaw cycles.

[0027] 3. In this invention, by constructing a dynamic rheological compensation mechanism, micro-nano bubbles form a lubrication effect similar to ball bearings in the slurry, effectively reducing the yield stress and plastic viscosity of the slurry and counteracting the thickening tendency of the slurry caused by carbonation. The digital twin control system monitors the rheological parameters of the slurry in real time. When false setting precursors are detected, the system automatically adjusts the multi-energy field parameter combination. Through the dispersion effect of ultrasonic vibration and the temperature control of microwaves, the system maintains the stability of the slurry's workability, ensuring that the concrete maintains good workability throughout the entire process of mixing, transportation, and pouring.

[0028] 4. This invention employs a modular design concept, and the external circulation bubble generation structure completely solves the industry problem of high-viscosity slurry clogging equipment, making micro-nano bubble technology truly suitable for industrial-grade continuous production needs. The microwave-transparent ceramic lining balances microwave permeability and wear resistance, capable of withstanding the high-intensity wear of concrete mixing over long periods. The 915MHz industrial-grade microwave system has sufficient penetration depth to meet the uniform heating requirements of large-volume concrete mixing. From silicate cement to geopolymers, from virgin aggregates to recycled aggregates, the system can achieve optimal mineralization effects through parameter adjustments, providing flexible negative carbon solutions for different engineering scenarios.

[0029] 5. In this invention, the dual-frequency ultrasonic crystal form control technology achieves directional intervention throughout the entire mineralization process through precise frequency switching; the microwave choke structure solves the compatibility problem between the microwave energy field and the metal stirring system; and the multi-level Venturi bubble generation technology enables the stable and large-scale generation of micro- and nano-bubbles. These technological innovations are not simply a superposition of functions, but rather a deep integration based on multi-field coupled reaction dynamics, forming an integrated technological barrier of "mechanism innovation - structural optimization - parameter matching - intelligent control." This makes it difficult for competitors to achieve equivalent performance through simple imitation, providing solid intellectual property protection for the industrial application of the technology. Attached Figure Description

[0030] Figure 1 This is an overall system block diagram of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0032] Example: Refer to Figure 1 A smart stirring system for in-situ mineralization of negative carbon cementitious materials includes: a resonant stirring host, a multi-field coupling generator, an external circulation micro-nano bubble carbon injection system, a sensing and monitoring module, and a digital twin smart control terminal. The stirring blades of the resonant stirring host are integrated and connected with the ultrasonic vibration node of the multi-field coupling generator; The microwave module of the multi-field coupling generator is connected to the metal shielding shell of the resonant stirring host through a waveguide interface, and the microwave energy acts on the internal space through the microwave transparent ceramic lining of the host.

[0033] The external circulation micro-nano bubble carbon injection system is connected to the side wall of the cylinder of the resonant stirring host through a tangential back injection nozzle.

[0034] The torque sensor of the sensing and monitoring module is installed on the stirring shaft of the resonant mixer, the infrared temperature sensor is installed on the outer wall of the cylinder of the resonant mixer, the laser particle size sensor is connected to the circulation pipeline of the external circulation micro-nano bubble carbon injection system, and the graphene conductivity sensor is set at the slurry sampling port of the resonant mixer.

[0035] The digital twin intelligent control terminal establishes bidirectional communication connections with the drive motor of the resonant stirring host, the power controller of the multi-field coupling device, the high-pressure pump frequency converter of the external circulation micro-nano bubble carbon injection system, and the data acquisition unit of the sensing and monitoring module via an industrial bus.

[0036] The resonant stirring unit has a sandwich structure consisting of a metal shielded shell, an insulation layer, and a microwave-safe transparent ceramic liner. The ceramic liner is made of 99% alumina ceramic or silicon nitride, with a dielectric loss tangent of tanδ < 0.001, microwave transmittance ≥ 95%, and Mohs hardness ≥ 9.

[0037] The stirring shaft is made of non-magnetic stainless steel and features a quarter-wavelength microwave choke. The stirring blades integrate multi-point distributed ultrasonic vibration nodes, employing a bending vibration mode, and are distributed along the shaft at different heights and angles. Radial vibration mode is also supported.

[0038] The resonant stirring host provides a quantitative basis for the staged stirring speed control of the resonant stirring host, the energy field parameter matching of the multi-field coupling generator, and the bubble injection rhythm of the external circulation micro-nano bubble carbon injection system through the reaction kinetic equation. By establishing a correlation model between reaction rate and energy field intensity, it guides the coordinated operation of each module.

[0039] The kinetic equation for the multi-energy field synergistic in-situ mineralization reaction of negative carbon cementitious materials is as follows: ; In the formula: r is the mineralization reaction rate, in units of mol / (L·s); k is the apparent rate constant, with units of k. Its value is determined by the temperature of the slurry and the cementitious material system; The concentration of free calcium ions in the slurry is expressed in mol / L. The concentration of dissolved CO2 in the slurry is expressed in mol / L. The ultrasonic power density of the multi-field coupling generator is expressed in W / L. The microwave power density of the multi-field coupling generator is expressed in W / g. N represents the stirring speed of the resonant mixer, expressed in r / min. α represents the reaction order of calcium ion concentration, with a value ranging from 0.6 to 0.9; β is the reaction order for CO2 concentration, with a value ranging from 0.4 to 0.7; γ is the ultrasonic power response order, with a value ranging from 0.2 to 0.4; δ is the microwave power response order, with a value ranging from 0.1 to 0.3; ε represents the reaction order at the stirring speed, with a value ranging from 0.3 to 0.5; The multi-field coupling generator includes a dual-frequency ultrasonic module and a selectable-frequency microwave module. The ultrasonic module supports dual-frequency switching between 20kHz±2kHz and 40kHz±2kHz, as well as reverberation sweep, with a power density of 50–200W / L. The microwave module can select between 915MHz or 2.45GHz frequencies, supports pulsed and continuous output, has a power density of 0.5–2.0W / g, and a duty cycle of 30%–70% in pulsed mode.

[0040] The external circulation micro / nano bubble carbon injection system includes a high-pressure pump, a multi-stage tandem Venturi cyclone shear generator, and tangential reinjection nozzles. The system operates at a pressure of 0.2-0.6 MPa, with the high-pressure pump output pressure at 0.3-0.5 MPa. The throat diameters of the multi-stage Venturi tubes are 8 mm, 6 mm, and 4 mm, respectively, with a cavitation number σ ≤ 0.8. The generated CO2 micro / nano bubbles have a particle size of 50-500 nm, an absolute Zeta potential ≥ 30 mV, and remain stable in the slurry for ≥ 10 minutes.

[0041] In the core quantification process of the multi-stage Venturi vortex shear generator, the dynamic viscosity and density of the slurry are first obtained through rheological testing based on the initial mix proportions and temperature parameters of the slurry. Secondly, for the series structure of the multi-stage Venturi, the contraction ratio, expansion angle, and inlet length of each stage throat are parametrically modeled. Fluid dynamics simulation is then used to model the velocity distribution and pressure field changes under different throat sizes. Subsequently, a correction term for the saturated vapor pressure of CO2 in the slurry is introduced, extending the traditional cavitation number formula into a corrected model applicable to a gas-liquid-solid three-phase system. By calculating the cavitation values ​​under different inlet fluid pressures and equivalent throat diameters, the occurrence threshold and intensity range of the cavitation effect are analyzed. When the cavitation number is in the optimal range of 0.3-0.7, the sudden pressure drop at the Venturi throat will trigger a violent cavitation bubble collapse effect. Combined with the disturbance effect of the swirling shear blades, the introduced CO2 gas can be sheared and broken into micro-nano bubbles with a diameter of 10-50 μm. If the cavitation number is too high (>0.7), the cavitation effect is insufficient, the bubble particle size is too large and it is easy to aggregate and float, and it cannot be stably dispersed in high viscosity slurry. If the cavitation number is too low (<0.3), excessive cavitation will lead to secondary breakage of solid particles in the slurry, increase system energy consumption and affect the mechanical properties of cementitious materials. By establishing a correlation database between cavitation number, bubble generation efficiency, and particle size distribution, a precise design of a multi-stage Venturi cyclone shear generator can be achieved: the first-stage throat uses a smaller contraction ratio (1:3) and a lower inlet pressure (0.2MPa) to control the cavitation number at approximately 0.6, prioritizing the initial shear dispersion of CO2 gas; the second-stage throat uses a larger contraction ratio (1:5) and a higher inlet pressure (0.4MPa) to control the cavitation number at approximately 0.4, further refining the bubble particle size to below 20μm; the third-stage throat uses a medium contraction ratio (1:4) and a gradually varying inlet pressure (0.2-0.3MPa) to control the cavitation number at approximately 0.5, maintaining the suspension stability of micro- and nano-bubbles in the slurry, ultimately ensuring that the CO2 mineralization and fixation efficiency is increased by more than 30% during carbon injection, while the bubble residence time in the slurry is extended to more than 120s.

[0042] The formula for the corrected cavitation number is: ; In the formula: σc represents the corrected cavitation number applicable to high-viscosity cementitious slurries; p is the fluid pressure at the Venturi inlet (Pa); p_v is the saturated vapor pressure (Pa) of CO2 in the gel slurry; ρ is the density of the cementitious paste (kg / m³) 3 ); v is the average fluid velocity (m / s) at the cross-section of the Venturi throat. μ is the dynamic viscosity of the gel slurry (Pa·s); d is the equivalent diameter of the Venturi throat (m); k is the swirl shear correction factor, with a value ranging from 0.2 to 0.5, determined by the tilt angle and number of swirl blades.

[0043] The sensing and monitoring module includes a graphene conductivity sensor, a torque sensor, an infrared temperature sensor, and a laser particle size sensor. Each sensor monitors the mineralization reaction rate, apparent viscosity, reaction temperature, and bubble particle size distribution, respectively. The module is equipped with a high-speed wireless transmission module with a sampling frequency ≥10Hz to ensure timely and stable data transmission.

[0044] A digital twin intelligent control terminal constructs a thermoacoustic-fluid multi-field coupled digital twin model to achieve phased adaptive control. Control parameters include stirring speed, ultrasonic frequency, amplitude, microwave power mode, and bubble injection parameters. The terminal is equipped with emergency control logic: when the slurry torque growth slope > 0.05 N·m / s, it automatically reduces microwave power by 30% and switches to ultrasonic dual-frequency reverberation; when the conductivity change rate < 0.01 S / (m·min), it increases microwave power to 1.5–2.0 W / g. The phased control is divided into three periods: during the dispersion carbon injection period, mechanical stirring operates at high speed, the ultrasonic module is activated at 20 kHz, the external circulation micro-nano bubble system is started, and the microwave module is turned off; during the nucleation and mineralization period, mechanical stirring operates at medium speed, the ultrasonic module switches to 40 kHz or dual-frequency reverberation, and the microwave module operates in pulse mode; during the curing and densification period, mechanical stirring operates at low speed, the ultrasonic module is intermittently activated, and the microwave module operates continuously at low power. When the conductivity stabilizes, the energy field and bubble system are turned off. The emergency control logic of the digital twin intelligent control terminal is as follows: when the slope of the slurry torque increase is >0.05 N·m / s, the microwave power is automatically reduced by 30% and the ultrasonic dual-frequency reverberation is switched; when the conductivity change rate is <0.01 S / (m·min), the microwave power is increased to 1.5-2.0 W / g. A method for preparing a negative carbon cementitious material, the method using the aforementioned in-situ mineralization intelligent stirring system for negative carbon cementitious materials, includes the following steps: S1: Add cementitious materials, aggregates, and mixing water, start the resonant mixing host at high speed, and simultaneously start the external circulation micro-nano bubble carbon injection system. Inject CO2 micro-nano bubbles into the mixing tank through the tangential back injection nozzle. At the same time, turn on the 20kHz ultrasonic band of the multi-field coupling generator to break up the cementitious particle agglomerates and peel off the initial hydration film, providing a uniform reaction substrate for the subsequent nucleation and mineralization stage, and ensuring that CO2 can fully contact the cementitious particles in the subsequent steps.

[0045] S2: After completing the dispersion and carbon injection in stage S1, adjust the stirring speed of the resonant stirring host to medium speed, switch the ultrasonic frequency band of the multi-field coupling generator to 40kHz, and turn on the microwave module pulse mode to maintain the slurry temperature at 40-50℃. Based on the torque data fed back by the sensor monitoring module in stage S1, adjust the ultrasonic amplitude and microwave power in real time to ensure the stable progress of the mineralization reaction and lay the foundation for the crystal transformation in the subsequent curing and densification stage.

[0046] S3: After the mineralization reaction in stage S2 reaches a stable state, reduce the stirring speed of the resonant stirring host to a low speed, adjust the ultrasonic system to intermittent operation mode, switch the microwave module to continuous low power output, and at the same time shut down the external circulation micro-nano bubble carbon injection system. Combined with the conductivity data fed back by the sensing and monitoring module in stage S2, fine-tune the microwave power to promote the directional transformation of crystal form, optimize the pore structure of the material, and finally complete the preparation of the negative carbon cementitious material.

[0047] In step S1, when the cementitious material system contains recycled aggregate, a pretreatment step is added before stage one: the recycled aggregate and cement slurry accounting for 5%-15% of the total cementitious material are put into the mixing host, the ultrasonic module is turned on at a frequency of 40-45kHz, the power density is 150-200W / L, and the treatment time is 0.5-2 minutes.

[0048] In step S2, the pulse duty cycle of the microwave module is 30%-70%. When the slurry torque is monitored to be ≥80 N·m, the microwave power is reduced by 20%-40%, and the ultrasound is switched to dual-frequency reverberation mode.

[0049] In step S3, the micro-nano bubble system runs continuously from stage one to stage two and is shut down in stage three. The ratio of bubble injection volume to cementitious material mass is 0.05-0.1:1.

[0050] Example 1: Preparation of industrial-grade negative carbon silicate cement concrete: The mix proportions include: P·O 42.5 cement 320kg / m³ 3 680kg / m³ of river sand 3 5-25mm continuously graded crushed stone 1100kg / m³ 3 High-purity food-grade CO2 (≥99.9%) and 144kg of mixing water (water-cement ratio 0.45) are used. This product is suitable for large-volume continuous production scenarios such as precast concrete component plants and commercial concrete mixing plants. The single batch mixing capacity can reach 6m³. 3 .

[0051] The pretreatment preparation includes: preheating the crushed stone to 30°C to avoid the low temperature slurry reducing the mineralization reaction rate; and dehydrating the CO2 gas through a molecular sieve drying tower to achieve a water content of ≤10ppm to prevent bubble aggregation and failure.

[0052] The preparation process includes the following steps: 1. Dispersed carbon injection period (0-60s): 1-1: Add all solid raw materials, start the mixing host in high-speed mode (35r / min), the blade linear velocity reaches 2.8m / s, and break up the mechanical agglomerates of aggregate and cement within 10s, reducing the agglomerate particle size from the initial 500μm to below 80μm; 1-2: The external circulation micro-nano bubble system is started, the high-pressure pump output pressure is stabilized at 0.4MPa, the three-stage Venturi generator (throat diameter 8mm / 6mm / 4mm) generates 100-300nm CO2 micro-nano bubbles, which are injected into the mixing tank at a speed of 12m / s through the tangential reinjection nozzle, and the bubble diffusion uniformity in the slurry reaches 95%; 1-3: The ultrasonic system is activated in 20kHz low-frequency high-energy mode with a power density of 150W / L. Eight ultrasonic vibration nodes on the impeller are synchronously excited, and the microjet peels away the initial hydration film on the surface of cement particles. (Ca...) 2 ⁺ The dissolution rate is increased by 40% compared to the case without ultrasound.

[0053] 2. Nucleation and mineralization period (60-180s) 2-1: The stirring speed was reduced to 25 r / min, and the ultrasonic system was switched to 40 kHz medium frequency high density mode to induce the directional generation of aragonite crystal nuclei. At 120 s, the proportion of aragonite crystal nuclei reached 75%, laying the foundation for subsequent crystal transformation. 2-2: The 915MHz microwave system was started in pulse mode (50% duty cycle) with a power density of 1.2W / g. The slurry temperature was maintained at 45℃ through volumetric heating effect, and the activation energy of the mineralization reaction was reduced by 25%. 2-3: Sensor closed-loop control: When the torque sensor monitoring value rises to 80 N·m (corresponding to a slurry yield stress of 300 Pa), the microwave power automatically drops to 0.8 W / g, the ultrasonic switch is switched to a 20 kHz + 40 kHz dual-frequency reverberation mode, and the slurry yield stress drops back to below 200 Pa, completely avoiding carbonization and false coagulation.

[0054] 3. Cultivation and densification period (180-240s) 3-1: The stirring speed was reduced to 15 r / min, the microwave system was switched to continuous low power mode (0.6 W / g), the slurry temperature was maintained at 40℃, and the conversion of aragonite to calcite was promoted, with a conversion rate of 0.008 mol / (L·s); 3-2: The ultrasonic system operates intermittently (3 seconds on, 2 seconds off), and the pulsed vibration accelerates ion diffusion, allowing calcite crystals to uniformly fill the capillary pores, resulting in a 12% reduction in porosity compared to the baseline group; 3-3: When the graphene conductivity sensor reading stabilizes at 0.8 S / m (corresponding to a mineralization reaction completion rate of ≥90%), the bubble system, microwave and ultrasound are automatically shut off. After continuing low-speed stirring for 30 seconds, the material is discharged. The coefficient of variation of the slurry uniformity is ≤3%.

[0055] The performance comparison of industrial-grade negative carbon silicate cement concrete is shown in the table below: Performance index Benchmark group (traditional stirring process) Experimental group (process of the present application) Improvement / improvement range 3d compressive strength (MPa) 32.0 42.3 +32.2% 28d compressive strength (MPa) 50.2 56.8 +13.1% 28d splitting tensile strength (MPa) 3.3 3.9 +18.2% CO2 sequestration rate (%) 6.1 18.5 +203.3% Initial fluidity (mm) 225 220 -2.2% 1h fluidity loss rate (%) 28 12 -57.1% 28d chloride ion resistance electric flux (C) 1850 980 -47.0% Fast freeze-thaw cycle times (times) 220 300 +36.4% Capillary absorption of water (kg / m 2 ·h) 1.2 0.78 -35.0% Example 2: High-content recycled aggregate concrete repair – integrated mineralization (2.45GHz microwave-adapted refined repair): The raw material composition includes: P·O 42.5 cement 280kg / m³ 3 It contains 50% recycled coarse aggregate (particle size 5-20mm, derived from demolished C30 concrete beams, crushing index 28%, water absorption rate 8.5%), 56kg fly ash (replacing 20% ​​cement), CO2 gas, and 134.4kg mixing water (water-cement ratio 0.48), suitable for scenarios such as old building component recycling, road base repair, and municipal engineering renovation.

[0056] Pretreatment preparation includes: after screening and high-pressure washing, the recycled aggregate is soaked in saturated lime water for 24 hours to replenish the calcium inside the aggregate. 2 ⁺ Reserves to improve the efficiency of mineralization remediation.

[0057] The preparation process specifically includes the following steps: 1. Pretreatment and repair period (0-60s): Add recycled aggregate and 10% by mass of cement slurry (about 33.6kg), start the mixing host in low speed mode (15r / min); turn on the ultrasonic system in 45kHz high frequency mode with a power density of 180W / L. The micro-jet generated by the vibration node forces the cement slurry to penetrate into the micro-cracks (width 0.05-0.2mm) of the recycled aggregate. The CaCO3 crystals generated by pre-mineralization fill the crack depth to more than 80%, and the surface bonding strength of the aggregate is increased by 25%.

[0058] 2. Dispersed carbon injection period (60-120s): Add the remaining cement, fly ash and mixing water, increase the stirring speed to 35r / min, and quickly mix to form a uniform slurry; start the external circulation micro-nano bubble system, with the high-pressure pump at 0.35MPa, generating 150-400nm CO2 bubbles, which are injected through tangential nozzles. The bubbles remain stable in the slurry for up to 10 minutes, and the gas-liquid contact area is increased by 3 times compared to ordinary bubbles.

[0059] 3. Nucleation and mineralization period (120-240s): The stirring speed is reduced to 25r / min, and the ultrasonic is switched to dual-frequency reverberation mode (20kHz+40kHz) for 90s to enhance the mineralization reaction in the interfacial transition zone (ITZ). The CaCO3 crystal formation rate in the ITZ reaches 0.01mol / (L·s); the 2.45GHz microwave system is started in pulse mode (60% duty cycle) with a power density of 1.0W / g to maintain the slurry temperature at 42℃ and promote the interfacial bonding between recycled aggregate and new slurry; sensor control: when the torque increases to 75N·m, the microwave power is reduced to 0.7W / g to avoid false setting of the slurry.

[0060] 4. Cultivation and densification period (240-300s): Reduce the stirring speed to 15r / min, switch the microwave to continuous low power (0.5W / g); run the ultrasonic intermittently to promote the transformation of aragonite to calcite at the ITZ, and reduce the thickness of the interface transition zone from 40μm in the reference group to 25μm; when the conductivity stabilizes at 0.75S / m, turn off all energy field systems, continue stirring for 30s and discharge the material.

[0061] The performance comparison of high-content recycled aggregate concrete is shown in the table below: Performance index Traditional process (no pretreatment + ordinary carbon injection) Process of the present application (ultrasonic pretreatment + micro-nano bubble carbon injection) Improvement / improvement range 3d compressive strength (MPa) 30.2 38.6 +27.8% 28d compressive strength (MPa) 45.6 52.4 +14.9% Recycled aggregate bonding strength (MPa) 2.1 2.93 +39.5% CO2 sequestration rate (%) 7.2 17.2 +138.9% Interface transition zone thickness (μm) 42 25 -40.5% Interface transition zone density (%) 68 99 +45.6% 28d sulfate attack resistance grade KS8 KS12 4 levels of improvement 1h fluidity loss rate (%) 32 15 -53.1% Example 3: Parameter optimization and performance verification of a multi-stage Venturi micro / nano bubble generator: To address the problem of unstable CO2 bubble dispersion in high-viscosity cementitious slurries (such as high-dosage slag slurries and geopolymer slurries), the structural parameters of a multi-stage Venturi cavitation generator were optimized to adapt to the large-scale production scenarios of negative carbon geopolymers and high-dosage solid waste cementitious materials.

[0062] Structural parameters and cavitation number calculation: A three-stage tandem Venturi tube system was used, with throat diameters of 8mm, 6mm, and 4mm respectively. The inlet pressure was 0.5MPa, the fluid velocity was 1.8m / s, and the cavitation number σ=0.8 (satisfying the significant cavitation condition). The generated CO2 micro-nano bubbles had a particle size distribution of 80-250nm, a Zeta potential of -38mV, and remained stable in the cement slurry for 12 minutes. The gas-liquid mass transfer efficiency reached 92%, which is 28% higher than that of a single-stage Venturi system.

[0063] The performance comparison of Venturi bubble generators with different structures is shown in the table below: Performance index Single-stage Venturi Two-stage Venturi Three-stage Venturi (present application) Improvement range (vs single-stage) Bubble average particle size (nm) 850 420 160 -81.2% 100-200nm bubble proportion (%) 12 45 85 +608.3% Zeta potential absolute value (mV) 22 28 38 +72.7% Bubble stability in slurry (min) 5 8 12 +140% Gas-liquid mass transfer efficiency (%) 72 85 92 +27.8% CO2 solubility enhancement factor 1.8 2.9 4.2 +133.3% Unit energy consumption of air bubbles (kW·h / m 3 ) 0.11 0.095 0.08 -27.3% Adapted maximum slurry viscosity (Pa·s) 0.08 0.12 0.2 +150% In summary: In this invention, the energy field synergy mechanism fundamentally breaks through the mass transfer bottleneck of traditional carbon injection technology. Micro-nano bubble technology disperses CO2 into stable gas-liquid interfaces at the nanoscale, greatly expanding the gas-liquid contact area and allowing CO2 to quickly penetrate into the internal pores of high-viscosity slurries. Ultrasonic vibration continuously breaks down the hydration passivation layer on the surface of the gelling particles, exposing more active reaction sites, while the microwave energy field accelerates ion migration rates through molecular thermal motion, forming a highly efficient synergistic chain. This results in an order-of-magnitude increase in CO2 mineralization and fixation efficiency, truly achieving the goal of negative carbon in industrial production.

[0064] In this invention, crystal form orientation control technology plays a crucial role in the mineralization process. Early-formed aragonite crystals are uniformly dispersed in the slurry at the nanoscale, providing ample nucleation sites for subsequent crystal form transformation. As the reaction progresses, the aragonite gradually transforms into calcite crystals. This transformation, accompanied by volume expansion, precisely fills the capillary pores within the slurry, optimizing the material's pore structure at the microscopic level. Simultaneously, the calcium carbonate crystals generated by the mineralization reaction form tight chemical bonds with the cementitious matrix, significantly improving the material's density. This not only leads to rapid early strength growth but also fundamentally improves long-term durability properties such as resistance to chloride ion penetration and freeze-thaw cycles.

[0065] In this invention, a dynamic rheological compensation mechanism is constructed, in which micro- and nano-bubbles form a lubrication effect similar to ball bearings in the slurry, effectively reducing the yield stress and plastic viscosity of the slurry and counteracting the thickening tendency of the slurry caused by carbonation. A digital twin control system monitors the rheological parameters of the slurry in real time. When signs of false setting are detected, the system automatically adjusts the multi-energy field parameter combination. Through the dispersion effect of ultrasonic vibration and the temperature control of microwaves, the system maintains the stability of the slurry's workability, ensuring that the concrete maintains good workability throughout the entire process of mixing, transportation, and pouring.

[0066] This invention employs a modular design concept, and the external circulation bubble generation structure completely solves the industry problem of high-viscosity slurry clogging equipment, making micro-nano bubble technology truly suitable for industrial-grade continuous production needs. The microwave-transparent ceramic lining balances microwave permeability and wear resistance, capable of withstanding the high-intensity wear of concrete mixing over long periods. The 915MHz industrial-grade microwave system has sufficient penetration depth to meet the uniform heating requirements of large-volume concrete mixing. From silicate cement to geopolymers, from virgin aggregates to recycled aggregates, the system can achieve optimal mineralization effects through parameter adjustments, providing flexible negative carbon solutions for different engineering scenarios.

[0067] In this invention, dual-frequency ultrasonic crystal form control technology achieves directional intervention throughout the entire mineralization process through precise frequency switching; the microwave choke structure solves the compatibility problem between microwave energy fields and metal stirring systems; and the multi-level Venturi bubble generation technology enables the stable and large-scale generation of micro- and nano-bubbles. These technological innovations are not simply a superposition of functions, but rather a deep integration based on multi-field coupled reaction dynamics, forming an integrated technological barrier of "mechanism innovation – structural optimization – parameter matching – intelligent control." This makes it difficult for competitors to achieve equivalent performance through simple imitation, providing solid intellectual property protection for the industrial application of the technology.

[0068] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the term "comprising" or any other variations thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0069] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A smart stirring system for in-situ mineralization of negative carbon cementitious materials, characterized in that: include: The components include a resonant stirring host, a multi-field coupling generator, an external circulation micro-nano bubble carbon injection system, a sensing and monitoring module, and a digital twin intelligent control terminal. The stirring blades of the resonant stirring host are integrated and connected to the ultrasonic vibration node of the multi-field coupling generator. The microwave module of the multi-field coupling generator is connected to the metal shielding shell of the resonant stirring host through a waveguide interface, and microwave energy is applied to the internal space through the microwave transparent ceramic lining of the host. The external circulation micro-nano bubble carbon injection system is connected to the cylinder side wall of the resonant stirring host through a tangential back injection nozzle; The torque sensor of the sensing and monitoring module is installed on the stirring shaft of the resonant mixer, the infrared temperature sensor is installed on the outer wall of the cylinder of the resonant mixer, the laser particle size sensor is connected to the circulation pipeline of the external circulation micro-nano bubble carbon injection system, and the graphene conductivity sensor is set at the slurry sampling port of the resonant mixer. The digital twin intelligent control terminal establishes bidirectional communication connections with the drive motor of the resonant stirring host, the power controller of the multi-field coupling device, the high-pressure pump frequency converter of the external circulation micro-nano bubble carbon injection system, and the data acquisition unit of the sensing and monitoring module via an industrial bus.

2. The intelligent stirring system for in-situ mineralization of negative carbon cementitious materials as described in claim 1, characterized in that: The resonant stirring host is a sandwich structure consisting of a metal shielded shell, a thermal insulation layer, and a microwave transparent ceramic liner; the ceramic liner is 99% alumina ceramic or silicon nitride, with a dielectric loss tangent tanδ < 0.001, microwave transmittance ≥ 95%, and Mohs hardness ≥ 9. The stirring shaft is made of non-magnetic stainless steel, and a quarter-wavelength microwave choke is installed on the shaft body; The kinetic equation for the multi-energy field synergistic in-situ mineralization reaction of the negative carbon cementitious material in the resonant stirring host is as follows: ； In the formula: r is the mineralization reaction rate, in units of mol / (L·s); k is the apparent rate constant, with units of . Its value is determined by the temperature of the slurry and the cementitious material system; The concentration of free calcium ions in the slurry is expressed in mol / L. The concentration of dissolved CO2 in the slurry is expressed in mol / L. The ultrasonic power density of the multi-field coupling generator is expressed in W / L. The microwave power density of the multi-field coupling generator is expressed in W / g. N represents the stirring speed of the resonant mixer, expressed in r / min. α represents the reaction order of calcium ion concentration, with a value ranging from 0.6 to 0.9; β is the reaction order for CO2 concentration, with a value ranging from 0.4 to 0.7; γ is the ultrasonic power response order, with a value ranging from 0.2 to 0.4; δ is the microwave power response order, with a value ranging from 0.1 to 0.3; ε represents the reaction order at which the stirring speed is increased, and its value ranges from 0.3 to 0.

5.

3. The intelligent stirring system for in-situ mineralization of negative carbon cementitious materials as described in claim 1, characterized in that: The multi-field coupling generator includes a dual-frequency ultrasonic module and a selectable-frequency microwave module.

4. The intelligent stirring system for in-situ mineralization of negative carbon cementitious materials as described in claim 1, characterized in that: The external circulation micro-nano bubble carbon injection system includes a high-pressure pump, a multi-stage series Venturi cyclone shear generator, and a tangential reinjection nozzle. The output pressure of the high-pressure pump is 0.3-0.5 MPa. The throat diameters of the multi-stage Venturi tubes are 8 mm, 6 mm, and 4 mm, respectively, and the cavitation number σ≤0.

8. The generated CO2 micro-nano bubbles have a particle size of 50-500 nm, an absolute value of Zeta potential ≥30 mV, and are stable in the slurry for ≥10 minutes. In the core quantification process of the multi-stage Venturi vortex shear generator, the dynamic viscosity and density of the slurry are first obtained through rheological testing based on the initial mix proportions and temperature parameters of the slurry. Secondly, for the series structure of the multi-stage Venturi, the contraction ratio, expansion angle, and inlet length of each stage throat are parametrically modeled, and the velocity distribution and pressure field changes under different throat sizes are simulated using fluid dynamics simulation. Subsequently, a correction term for the saturated vapor pressure of CO2 in the slurry is introduced, extending the traditional cavitation number formula to a corrected model applicable to a gas-liquid-solid three-phase system. By calculating the cavitation values ​​under different inlet fluid pressures and equivalent throat diameters, the occurrence threshold and intensity range of the cavitation effect are analyzed. The corrected cavitation number formula is as follows: ； In the formula: σc represents the corrected cavitation number applicable to high-viscosity cementitious slurries; p is the fluid pressure at the Venturi inlet; p_v is the saturated vapor pressure of CO2 in the cementitious slurry; ρ is the density of the cementitious paste; v is the average fluid velocity at the cross-section of the Venturi throat; μ is the dynamic viscosity of the cementitious slurry; d is the equivalent diameter of the Venturi throat; k is the swirl shear correction factor, with a value ranging from 0.2 to 0.5, determined by the tilt angle and number of swirl blades.

5. The intelligent stirring system for in-situ mineralization of negative carbon cementitious materials as described in claim 1, characterized in that: The sensing and monitoring module includes a graphene conductivity sensor, a torque sensor, an infrared temperature sensor, and a laser particle size sensor; each sensor is responsible for monitoring the mineralization reaction rate, apparent viscosity, reaction temperature, and bubble particle size distribution.

6. The intelligent stirring system for in-situ mineralization of negative carbon cementitious materials as described in claim 1, characterized in that: The digital twin intelligent control terminal constructs a thermoacoustic flow multi-field coupled digital twin model to achieve phased adaptive control; The control parameters include stirring speed, ultrasonic frequency, amplitude, microwave power mode, and bubble injection parameters. The emergency control logic of the digital twin intelligent control terminal is as follows: when the slope of the slurry torque growth is >0.05 N·m / s, the microwave power is automatically reduced by 30% and the ultrasonic dual-frequency reverberation is switched; when the conductivity change rate is <0.01 S / (m·min), the microwave power is increased to 1.5-2.0 W / g.

7. A method for preparing a carbon negative cementitious material, characterized in that: The preparation method uses the intelligent stirring system for in-situ mineralization of negative carbon cementitious materials as described in any one of claims 1 to 6, and the method includes the following steps: S1: Add cementitious materials, aggregates and mixing water, start the resonant mixing host to run at high speed, and simultaneously start the external circulation micro-nano bubble carbon injection system. Inject CO2 micro-nano bubbles into the mixing tank through the tangential back injection nozzle. At the same time, turn on the 20kHz ultrasonic band of the multi-field coupling generator to break up the cementitious particle agglomerates and peel off the initial hydration film, providing a uniform reaction substrate for the subsequent nucleation and mineralization stage. S2: After completing the dispersion and carbon injection in stage S1, adjust the stirring speed of the resonant stirring host to medium speed, switch the ultrasonic frequency band of the multi-field coupling generator to 40kHz, turn on the microwave module pulse mode to maintain the slurry temperature at 40-50℃, and adjust the ultrasonic amplitude and microwave power in real time based on the torque data fed back by the sensor monitoring module in stage S1. S3: After the mineralization reaction in stage S2 reaches a stable state, reduce the stirring speed of the resonant stirring host to a low speed, adjust the ultrasonic system to intermittent operation mode, switch the microwave module to continuous low power output, and at the same time shut down the external circulation micro-nano bubble carbon injection system. Combined with the conductivity data fed back by the sensing and monitoring module in stage S2, fine-tune the microwave power to promote the directional transformation of crystal form, optimize the pore structure of the material, and finally complete the preparation of the negative carbon cementitious material.

8. The intelligent stirring system for in-situ mineralization of negative carbon cementitious materials as described in claim 7, characterized in that: In step S1, when the cementitious material system contains recycled aggregate, a pretreatment step is added before stage one: the recycled aggregate and cement slurry accounting for 5%-15% of the total cementitious material are put into the mixing host, the ultrasonic module is turned on at a frequency of 40-45kHz, the power density is 150-200W / L, and the treatment time is 0.5-2 minutes.

9. The intelligent stirring system for in-situ mineralization of negative carbon cementitious materials as described in claim 7, characterized in that: In step S2, the pulse duty cycle of the microwave module is 30%-70%. When the slurry torque is monitored to be ≥80 N·m, the microwave power is reduced by 20%-40%, and the ultrasound is switched to dual-frequency reverberation mode.

10. The intelligent stirring system for in-situ mineralization of negative carbon cementitious materials and its preparation method as described in claim 7, characterized in that: In step S3, the micro-nano bubble system operates continuously from stage one to stage two and is shut down in stage three. The ratio of bubble injection volume to cementitious material mass is 0.05-0.1:1.

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