A wet mineralization aid for recycling aggregates, a mineralization method and an auxiliary mineralization device

Abstract

The application relates to a wet mineralization auxiliary agent for recycling aggregate, a mineralization method and an auxiliary mineralization device, and relates to the technical fields of recycling aggregate processing and building materials. The mineralization auxiliary agent comprises the following components in parts by weight: 8-10 parts of polyethylene imine (PEI), 4-6 parts of calcium hydroxide and 1-3 parts of acetic acid. The mineralization auxiliary agent and the mineralization method provided by the application not only realize synchronous improvement of the performance of the aggregate and the carbon fixation efficiency, but also simplify the wet mineralization process, and provide a novel green technical scheme for industrialized high-performance recycled aggregate preparation.

Description

Technical Field

[0001] This invention relates to the field of recycled aggregate processing and building materials technology, and in particular to a wet mineralization aid, mineralization method and auxiliary mineralization device for recycled aggregates. Background Technology

[0002] With the acceleration of urbanization and the increase in construction and demolition activities, a large amount of construction waste has been generated, including recycled aggregates such as concrete blocks, bricks, and mortar. These recycled aggregates are formed through crushing and screening, but their physical and mechanical properties are relatively poor, exhibiting problems such as high water absorption, large porosity, low apparent density, and insufficient compressive and abrasion resistance, severely limiting their application in new concrete and building materials. Traditional methods for improving recycled aggregates often involve simple washing, screening, or heat treatment, but the effects are limited, especially in terms of improving pore structure and compressive strength, failing to meet the requirements of high-performance building materials.

[0003] In recent years, the use of carbon dioxide mineralization technology to improve the properties of recycled aggregates has attracted attention. This technology involves the reaction of CO2 with calcium in the aggregate. 2+ Mg 2+ Plasma reactions generate carbonate deposits, which fill pores, improve density and mechanical properties, and significantly reduce water absorption and crushing value. Existing technologies typically use single alkaline substances or inorganic salts as mineralization aids. While these can promote the mineralization of recycled aggregates to some extent, their solidification rate is slow, calcium carbonate deposition is uneven, and they are unlikely to significantly improve aggregate mechanical properties. During the mineralization process, a single aid system cannot simultaneously achieve high CO2 absorption and uniform calcium carbonate formation. Water easily penetrates the aggregate pores, causing pore water residue or rupture of the crystallized film on the aggregate surface, thereby reducing mineralization efficiency and limiting the long-term stability of aggregate performance improvements.

[0004] Therefore, there is an urgent need to develop a method for processing recycled aggregates that can efficiently carry out mineralization reactions under wet conditions, improve CO2 capture efficiency and calcium carbonate deposition uniformity, and significantly improve the water absorption, apparent density and compressive strength of recycled aggregates, so as to realize the high added value utilization of recycled aggregates and provide reliable raw material guarantee and technical support for the preparation of green building materials. Summary of the Invention

[0005] The purpose of this invention is to improve the shortcomings of existing technologies, such as low efficiency of wet mineralization of recycled aggregates, uneven calcium carbonate deposition, and limited improvement in the mechanical properties of aggregates, and to provide a wet mineralization aid, mineralization method, and auxiliary mineralization device for recycled aggregates.

[0006] The first aspect of this invention provides a wet mineralization aid for recycled aggregates, employing the following technical solution:

[0007] A wet mineralization aid for recycled aggregates comprises the following components in parts by weight: 8-10 parts polyethyleneimine (PEI), 4-6 parts calcium hydroxide, and 1-3 parts acetic acid.

[0008] By adopting the above technical solution, PEI, as the core mineralization promoter, provides CO2-loving sites through its abundant amino groups (-NH2 / -NH-), which can form ammonium carbonate complexes with CO2, improving the absorption efficiency and residence time of CO2 in the aqueous phase, thereby accelerating the formation rate of calcium carbonate; calcium hydroxide, as an alkaline reactant, dissolves in the aqueous phase to produce Ca. 2+ and OH - This provides the reaction conditions for carbonate formation and calcium carbonate deposition; acetic acid, when added directly to the mineralization solution, can activate the aggregate surface and promote Ca2+ deposition. The acetic acid is dissolved, and some of the acetic acid is neutralized by calcium hydroxide to generate acetate ions, which does not affect the overall alkaline environment. This helps to form a uniform calcium carbonate deposit, improves the mineralization effect, and allows calcium carbonate to be uniformly deposited on the surface and in the pores of the aggregate, thereby improving the stability of the pore structure and mechanical properties of the recycled aggregate.

[0009] Preferably, the wet mineralization aid for recycled aggregates comprises the following components in parts by weight: 8 parts polyethyleneimine (PEI), 5 parts calcium hydroxide, and 2 parts acetic acid.

[0010] A second aspect of the present invention provides a wet mineralization method for recycled aggregates, employing the aforementioned mineralization aid, comprising the following steps:

[0011] S1. Dissolve the mineralizing agent in water to prepare a mineralizing solution;

[0012] S2. Immerse the recycled aggregate to be mineralized into the mineralization solution prepared in S1, so that the mineralization solution fully wets the surface and pores of the recycled aggregate.

[0013] S3. Wet mineralization reaction is carried out in the presence of CO2;

[0014] S4. After mineralization is completed, the aggregate is dried or used in the next step.

[0015] By adopting the above technical solution, the three additives work synergistically in the wet mineralization process: PEI captures and retains CO2, improving solubility and reaction residence time; calcium hydroxide provides Ca... 2+ And alkaline medium, so that CO3 2- It is generated and deposited as calcium carbonate; acetic acid promotes the activation of aggregate surface and Ca. 2+The soluble calcium carbonate crystals are formed and distributed uniformly. At the same time, the presence of acetic acid can also synergistically promote the dissolution and redeposition of Ca-based hydration products in the mineralization reaction, thereby improving the mineralization effect. Calcium carbonate is uniformly deposited on the surface and in the pores of the aggregate, improving the stability of the pore structure and mechanical properties of the recycled aggregate. Through this synergistic effect, the mineralization aid not only significantly enhances the ability of the recycled aggregate to absorb CO2, but also improves the uniformity and density of calcium carbonate deposition on the surface and in the pores of the aggregate.

[0016] Preferably, in the above-mentioned mineralization method, the concentrations of each component in the mineralization solution are: polyethyleneimine 0.5–0.7 g / L, calcium hydroxide 0.27–0.4 g / L, and acetic acid 0.07–0.2 g / L.

[0017] Preferably, the concentrations of each component in the mineralization solution are: polyethyleneimine 0.53 g / L, calcium hydroxide 0.33 g / L, and acetic acid 0.13 g / L.

[0018] Preferably, in the above-mentioned mineralization method, in step S3, the mineralization temperature is 40–60°C, the CO2 pressure is 0.1–0.2 MPa, and the mineralization time is 12–48 h.

[0019] Preferably, in the above-mentioned mineralization method, in step S3, the mineralization temperature is 50℃, the CO2 pressure is 0.15MPa, and the mineralization time is 24h.

[0020] By adopting the above technical solution and optimizing the mineralization conditions and parameters, the overall optimization of CO2 absorption efficiency, mineralization rate and calcium carbonate deposition uniformity is achieved while ensuring a significant improvement in the mechanical properties of aggregates. The aggregate water absorption rate and crushing value are reduced and the apparent density is increased. This method is suitable for the industrial preparation of high-performance recycled aggregates and provides a simple and efficient technical solution for the resource utilization of construction waste and the development of low-carbon green building materials.

[0021] A third aspect of the present invention provides an auxiliary mineralization apparatus for implementing the above-described mineralization method, comprising a tower body, wherein a movable screen, a water tank, a lifting component, an air supply component, and a spraying assembly are provided inside the tower body. The movable screen is slidably disposed inside the tower body and is used to place aggregates to be mineralized. The water tank is disposed inside the tower body and is used to fill mineralization liquid. The lifting component is connected to the movable screen and is used to drive the movable screen to rise and fall. The air supply component is used to provide CO2 into the tower body. The spraying assembly is disposed on the tower body and is used to circulate and spray the mineralization liquid in the water tank.

[0022] By adopting the above technical solution

[0023] In summary, this application includes at least one of the following beneficial technical effects:

[0024] 1. Through the synergistic effect of three auxiliary agents: PEI captures and retains CO2, improving solubility and reaction residence time; calcium hydroxide provides Ca... 2+ And alkaline medium, so that CO3 2- It is generated and deposited as calcium carbonate; acetic acid promotes the activation of aggregate surface and Ca. 2+ The soluble calcium carbonate crystals are formed and distributed uniformly. At the same time, the presence of acetic acid can also synergistically promote the dissolution and redeposition of Ca-based hydration products in the mineralization reaction, thereby improving the mineralization effect. Calcium carbonate is uniformly deposited on the surface and in the pores of the aggregate, improving the stability of the pore structure and mechanical properties of the recycled aggregate. Through this synergistic effect, the mineralization aid not only significantly enhances the ability of the recycled aggregate to absorb CO2, but also improves the uniformity and density of calcium carbonate deposition on the surface and in the pores of the aggregate.

[0025] 2. The mineralization method provided in this application not only simplifies the wet mineralization process, but also achieves simultaneous improvement in aggregate performance and carbon sequestration efficiency, providing a new green technology solution for the industrial preparation of high-performance recycled aggregates.

[0026] 3. The auxiliary mineralization device provided in this application improves the convenience and safety of mineralization operations. Attached Figure Description

[0027] Figure 1 This is a cross-sectional view of the auxiliary mineralization device provided in Embodiment 1 of this application.

[0028] Reference numerals: 1. Tower body; 11. Upper space; 12. Transition space; 13. Lower space; 14. Side door; 15. Heating element; 16. Side pipe; 2. Movable screen; 21. Sealing strip; 3. Water tank; 31. Liquid inlet pipe; 32. Liquid outlet pipe; 4. Lifting element; 5. Air supply element; 6. Spray assembly; 61. Spray pump; 611. Suction pipe; 612. Conveying pipe; 62. Spray pipe; 63. Spray head. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Modifications or equivalent substitutions made by those skilled in the art based on their understanding of the technical solutions of this invention, without departing from the spirit and scope of the invention, should all be covered within the protection scope of this invention.

[0030] Unless otherwise specified, the reagents, instruments and equipment used in the following examples are all commercially available products. Other specific conditions not specified shall be performed in accordance with conventional conditions or the manufacturer's recommendations.

[0031] The Chinese definitions of chemical abbreviations in this application are based on the generally accepted understanding within the industry.

[0032] The sources of some of the raw materials used in this application are as follows:

[0033] Recycled aggregate: derived from construction waste recycling plants, made from crushed construction waste concrete, with a particle size of 4.75–9 mm and a water absorption rate of 6–10%;

[0034] Polyethyleneimine (PEI): Purchased from Maclean's, CAS No. 9002-98-6, purity ≥99%;

[0035] Calcium hydroxide (Ca(OH)2): purchased from Yuanfeng Chemical, CAS number 1305-62-0, purity ≥95%;

[0036] Acetic acid (CH3COOH): purchased from Maclean's, CAS number 64-19-7, purity ≥98%;

[0037] Unless otherwise specified, reagents and procedures should be based on industry-standard sources, specifications, and practices.

[0038] I. Implementation Examples

[0039] Example 1

[0040] This embodiment provides an auxiliary mineralization device for recycled aggregates. In this embodiment, terms such as "fixed installation," "fixed connection," and "fixed connection" are common fixing methods in the prior art, such as welding, riveting, and screws. Unless otherwise specified, terms such as "rotational connection" and "rotationally installed" in this embodiment refer to common rotational installation methods in the prior art. Components required for rotation, such as bearings, are not within the scope of protection of this application and will not be described in detail. The functions, control, and power supply methods of all electrical components are common technical means in the prior art, and this application has not improved them and are not within the scope of protection of this application. Therefore, this application will not describe them in detail.

[0041] Furthermore, the selection of materials and strength limitations for all components in this application can be made and arranged by those skilled in the art based on the site environment and the requirements of relevant national or industry standards, and are not within the scope of protection of this application. Therefore, this application will not elaborate on these points.

[0042] Reference Figure 1An auxiliary mineralization device for recycled aggregate includes a tower body 1. The tower body 1 is equipped with a movable screen 2, a water tank 3, a lifting component 4, an air supply component 5, and a spray assembly 6. The tower body 1 has an upper space 11, a transition space 12, and a lower space 13. The upper space 11 is located above the lower space 13 and the inner diameter of the upper space 11 is smaller than the inner diameter of the lower space 13. The transition space 12 is located between the upper space 11 and the lower space 13 and is used to connect the upper space 11 and the lower space 13.

[0043] Reference Figure 1 The movable screen 2 is located in the upper space 11. The outer diameter of the movable screen 2 is slightly smaller than the inner diameter of the upper space 11 (the distance is no more than 1 cm). The outer edge of the movable screen 2 is provided with a sealing strip 21, which is wrapped around the outer periphery of the movable screen 2. The lifting component 4 is located at the top of the tower body 1 and drives the movable screen 2 to move up and down between the upper space 11 and the lower space 13. In this embodiment, the lifting component 4 is a hydraulic cylinder. The driving end of the hydraulic cylinder extends into the upper space 11 and is coaxially fixed to the movable screen 2. In other feasible embodiments, the lifting component 4 can be replaced by other components with lifting functions, such as electric actuators, cylinders, etc.

[0044] Reference Figure 1 A side opening communicating with the upper space 11 is provided on the outer wall of the tower body 1. A side door 14 is rotatably provided on the side opening. The connection method and sealing means between the side door 14 and the tower body 1 are the same as those in the prior art of carbonization towers, and will not be described in detail here.

[0045] Reference Figure 1 The gas supply component 5 is installed on the tower body 1 and is used to supply carbon dioxide into the tower body 1. The gas supply component 5 is a carbon dioxide gas delivery pump. The gas inlet end of the delivery pump is connected to an external carbon dioxide gas source (gas cylinder or other gas storage equipment). The gas outlet end of the delivery pump extends into the upper space 11 through a gas delivery pipe. The tower body 1 is equipped with a detection device for detecting carbon dioxide pressure (not shown in the figure). The signal output end of the detection device is connected to an external control system. When the internal volume and temperature of the tower body 1 are determined, the pressure of carbon dioxide in the tower body 1 can be adjusted by adjusting the gas delivery rate.

[0046] Reference Figure 1 The transition space 12 extends downward in a funnel shape, connecting the upper space 11 and the lower space 13. The water tank 3 is fixed in the lower space 13, with its opening facing upward. The inner diameter of the water tank 3 is larger than the outer diameter of the movable screen 2. The water tank 3 is used to fill the mineralizing liquid. The outer wall of the tower body 1 is provided with an inlet pipe 31 for adding mineralizing liquid into the water tank 3. The outer wall at the bottom of the water tank 3 is provided with a drain pipe 32 for discharging mineralizing liquid. The drain pipe 32 extends outside the tower body 1. Both the inlet pipe 31 and the drain pipe 32 are provided with control valves (not shown in the figure) to control their opening and closing.

[0047] Reference Figure 1 The lower space 13 is equipped with a heating element 15 for heating the water tank 3. In this embodiment, the heating element 15 is an electric heating tube. The electric heating tube is spirally coiled on the bottom wall of the lower space 13 and abuts against the lower surface of the water tank 3. In other feasible embodiments, the electric heating tube can also be coiled on the outer wall and lower surface of the water tank 3. The control end of the electric heating tube extends out of the tower body 1 and is connected to an external power supply and control system. The water tank 3 is equipped with a temperature detector (not shown in the figure) for detecting the liquid temperature. The signal output end of the temperature detector is connected to the external control system.

[0048] Reference Figure 1 Multiple side pipes 16 are also provided at intervals on the outer wall of the tower body 1. The two ends of the side pipes 16 are connected to the upper space 11 and the water tank 3 respectively to realize the circulation of carbon dioxide gas.

[0049] Reference Figure 1 The spray assembly 6 is installed on the tower body 1 and connects the water tank 3 with the upper space 11. The spray assembly 6 includes a spray pump 61, a spray pipe 62 and a spray head 63. The spray pump 61 is fixed on the outer wall of the tower body 1 and its inlet end is connected to the water tank 3 through a suction pipe 611. The spray pipe 62 is fixed on the top wall of the upper space 11. The outlet end of the spray pump 61 is connected to the spray pipe 62 through a delivery pipe 612. There are multiple spray heads 63. The multiple spray heads 63 are spaced apart on the spray pipe 62 and the nozzles face downwards. The movable screen 2 is located below the spray head 63.

[0050] In this embodiment, the model and specifications of all detection elements are not limited, only that they have the corresponding detection function. In addition, other necessary components on the auxiliary mineralization device that are not described in this embodiment (such as pressure relief valves, inspection ports, etc.) are based on common components in the prior art. This application has not improved them, so they are not considered as limitations on this application.

[0051] The auxiliary mineralization device provided in this embodiment operates as follows: The prepared mineralization liquid is added to the water tank 3 through the inlet pipe 31. The side door 14 is opened, and the recycled aggregate to be mineralized is placed into the movable screen 2. After the side door 14 is closed and sealed, the heating element 15 is activated to heat the mineralization liquid to the specified temperature. The lifting element 4 is activated to move the movable screen 2 into the water tank 3 and immerse it in the mineralization liquid. Then, the gas supply element 5 is turned on to deliver carbon dioxide gas into the tower body 1. At the same time, the spray pump 61 is activated. After the mineralization liquid passes through the conveying pipe 612 and the spray pipe 62, it is sprayed out from the spray head 63, so that the upper CO2 gas is carried into the lower mineralization liquid. According to the set pressure, the gas delivery volume is adjusted. After the mineralization reaction is completed, the lifting component 4 drives the movable screen 2 to move up into the upper space 11. The mineralization liquid falls back into the water tank 3 through the screen holes. The sealing strip 21 is pressed against the movable screen 2 and the inner wall of the tower body 1. The gas pressure in the upper space 11 increases. At this time, the upper carbon dioxide gas enters the water tank 3 through the side pipe 16 to achieve balance, so as to improve the safety of operation. The mineralized aggregate is dried in the movable screen 2 (natural drying or hot air circulation drying can be selected). After drying, the side door 14 is opened, and the mineralized aggregate is removed before the next batch of aggregate is mineralized.

[0052] The mineralization of recycled aggregates using the auxiliary mineralization device provided in this embodiment is fully controllable, reduces carbon dioxide gas leakage, and improves operational safety.

[0053] Example 2

[0054] This embodiment provides a wet mineralization aid for recycled aggregates and a wet mineralization method.

[0055] A wet mineralization aid for recycled aggregates comprises the following components in parts by weight: 8 parts polyethyleneimine (PEI), 5 parts calcium hydroxide, and 2 parts acetic acid.

[0056] A wet mineralization method for recycled aggregates, using the auxiliary mineralization device provided in Example 1, includes the following steps:

[0057] S1. Dissolve the mineralizing agent in water to prepare a mineralizing solution.

[0058] Specifically, taking 15L of water as an example, first dissolve 5g of calcium hydroxide in water, stir evenly, then add 8g of PEI and stir thoroughly, and finally add 2g of acetic acid. After stirring evenly, a mineralized solution is obtained. At this time, the concentrations of each component in the mineralized solution are: polyethyleneimine 0.53 g / L, calcium hydroxide 0.33 g / L, and acetic acid 0.13 g / L.

[0059] S2. Immerse the recycled aggregate to be mineralized into the mineralization solution prepared in S1, so that the mineralization solution fully wets the surface and pores of the recycled aggregate.

[0060] Specifically, a sufficient amount of mineralizing liquid is prepared according to the volume of the water tank, the mineralizing liquid is added into the water tank, and then the recycled aggregate to be mineralized is placed in the movable screen. The lifting device is activated to make the movable screen descend into the water tank and be submerged in the mineralizing liquid, so that the mineralizing liquid fully wets the gaps between the recycled aggregate.

[0061] S3. Wet mineralization reaction is carried out in the presence of CO2.

[0062] Specifically, the heating element is activated to raise the temperature of the mineralizing solution to 40°C, and the gas supply element is activated to input CO2 gas into the tower. At the same time, the spray pump is activated, and the mineralizing solution circulates between the water tank and the spray pipe, so that the upper CO2 gas is carried into the lower mineralizing solution. The CO2 pressure in the tower is controlled at 0.1 MPa, and mineralization is carried out continuously for 12 hours.

[0063] S4. After mineralization is completed, the aggregate is dried or used in the next step.

[0064] Specifically, after mineralization is completed, the gas supply is turned off, the lifting mechanism is activated to drive the movable screen back to the upper space, and the CO2 in the upper space flows back to the mineralization liquid in the lower space to release pressure; the upper mineralized aggregate is dried (natural drying), and after drying, it is removed from the side door, while the next batch of aggregate enters the upper space, realizing continuous batch operation.

[0065] Example 3

[0066] This embodiment provides a wet mineralization aid for recycled aggregates and a wet mineralization method. The difference from Embodiment 2 is that the mineralization conditions are different. Specifically, the mineralization liquid temperature is 50°C, the CO2 pressure in the tower is 0.15 MPa, and the mineralization time is 24 h. The rest is the same as in Embodiment 2.

[0067] Example 4

[0068] This embodiment provides a wet mineralization aid for recycled aggregates and a wet mineralization method. The difference from Embodiment 2 is that the weight parts of the mineralization aid are: 8 parts of polyethyleneimine (PEI), 5 parts of calcium hydroxide, and 1 part of acetic acid. The mineralization conditions are also different. Specifically, the concentrations of each component in the mineralization solution are: 0.53 g / L of polyethyleneimine, 0.33 g / L of calcium hydroxide, and 0.07 g / L of acetic acid. The temperature of the mineralization solution is 50°C, the CO2 pressure in the tower is 0.15 MPa, and the mineralization time is 24 h. The rest is the same as in Embodiment 2.

[0069] Example 5

[0070] This embodiment provides a wet mineralization aid for recycled aggregates and a wet mineralization method. The difference from Embodiment 2 is that the weight parts of the mineralization aid are: 10 parts of polyethyleneimine (PEI), 5 parts of calcium hydroxide, and 2 parts of acetic acid. The mineralization conditions are also different. Specifically, the concentrations of each component in the mineralization solution are: 0.67 g / L of polyethyleneimine, 0.33 g / L of calcium hydroxide, and 0.13 g / L of acetic acid. The temperature of the mineralization solution is 50°C, the CO2 pressure in the tower is 0.1 MPa, and the mineralization time is 24 h. The rest is the same as in Embodiment 2.

[0071] Example 6

[0072] This embodiment provides a wet mineralization aid for recycled aggregates and a wet mineralization method. The difference from Embodiment 2 is that the weight parts of the mineralization aid are: 8 parts of polyethyleneimine (PEI), 5 parts of calcium hydroxide, and 3 parts of acetic acid. The mineralization conditions are also different. Specifically, the concentrations of each component in the mineralization solution are: 0.53 g / L of polyethyleneimine, 0.33 g / L of calcium hydroxide, and 0.2 g / L of acetic acid. The temperature of the mineralization solution is 60°C, the CO2 pressure in the tower is 0.2 MPa, and the mineralization time is 36 h. The rest is the same as in Embodiment 2.

[0073] Example 7

[0074] This embodiment provides a wet mineralization aid for recycled aggregates and a wet mineralization method. The difference from Embodiment 2 is that the weight parts of the mineralization aid are: 8 parts of polyethyleneimine (PEI), 4 parts of calcium hydroxide, and 2 parts of acetic acid. The mineralization conditions are also different, specifically: 0.53 g / L of polyethyleneimine, 0.27 g / L of calcium hydroxide, and 0.13 g / L of acetic acid; the mineralization liquid temperature is 50°C; the CO2 pressure in the tower is 0.15 MPa; and the mineralization time is 24 h. The rest is the same as in Embodiment 2.

[0075] Example 8

[0076] This embodiment provides a wet mineralization aid for recycled aggregates and a wet mineralization method. The difference from Embodiment 2 is that the weight parts of the mineralization aid are: 8 parts of polyethyleneimine (PEI), 6 parts of calcium hydroxide, and 2 parts of acetic acid. The mineralization conditions are also different, specifically: 0.53 g / L of polyethyleneimine, 0.40 g / L of calcium hydroxide, and 0.13 g / L of acetic acid. The mineralization liquid temperature is 50°C, the CO2 pressure in the tower is 0.15 MPa, and the mineralization time is 24 h. The rest is the same as in Embodiment 2.

[0077] Example 9

[0078] This embodiment provides a wet mineralization aid for recycled aggregates and a wet mineralization method. The difference from Embodiment 2 is that the weight parts of the mineralization aid are: 8 parts of polyethyleneimine (PEI), 5 parts of calcium hydroxide, and 2 parts of acetic acid. The mineralization conditions are also different, specifically: the mineralization liquid temperature is 50°C, the CO2 pressure in the tower is 0.15 MPa, and the mineralization time is 48 h. The rest is the same as in Embodiment 2.

[0079] Example 10

[0080] This embodiment provides a wet mineralization aid for recycled aggregates and a wet mineralization method. The difference from Embodiment 2 is that the weight parts of the mineralization aid are: 10 parts of polyethyleneimine (PEI), 5 parts of calcium hydroxide, and 2 parts of acetic acid. The mineralization conditions are also different, specifically: the mineralization liquid temperature is 50°C, the CO2 pressure in the tower is 0.15 MPa, the mineralization time is 24 h, the drying method is to circulate hot air in the upper space, the hot air temperature is 80°C, the initial relative humidity is 40%, the hot air velocity is 1-3 m / s, and the ventilation drying time is 3 h. The rest is the same as in Embodiment 2. In other feasible embodiments, the hot air drying conditions can be adjusted accordingly.

[0081] The specific differences between Examples 2-10 are shown in Table 1:

[0082] Table 1 Raw material ratio and operating parameters

[0083]

[0084] II. Comparative Example

[0085] Comparative Example 1

[0086] This comparative example provides a wet mineralization method, which differs from Example 2 in that no mineralization aid is used, and an equal amount of water is used to replace the mineralization solution. The remaining operations are the same as in Example 2.

[0087] Comparative Example 2

[0088] This comparative example provides a wet mineralization method. The difference from Example 2 is that only PEI is used as the mineralization aid, the amount of PEI added remains unchanged, and the rest of the operation is the same as in Example 2.

[0089] Comparative Example 3

[0090] This comparative example provides a wet mineralization method, which differs from Example 2 in that only calcium hydroxide is used as the mineralization aid, the amount of calcium hydroxide added remains unchanged, and the rest of the operation is the same as in Example 2.

[0091] Comparative Example 4

[0092] This comparative example provides a wet mineralization method. The difference from Example 2 is that only acetic acid is used as the mineralization aid, the amount of acetic acid added remains unchanged, and the rest of the operation is the same as in Example 2.

[0093] Comparative Example 5

[0094] This comparative example provides a wet mineralization method, which differs from Example 2 in that the mineralization aid includes 8 parts PEI and 5 parts calcium hydroxide, and no acetic acid is used. The remaining operations are the same as in Example 2.

[0095] Comparative Example 6

[0096] This comparative example provides a wet mineralization method, which differs from Example 2 in that the mineralization aid includes 8 parts PEI and 2 parts acetic acid, and no calcium hydroxide is used. The remaining operations are the same as in Example 2.

[0097] Comparative Example 7

[0098] This comparative example provides a wet mineralization method, which differs from Example 2 in that the mineralization aid includes 5 parts calcium hydroxide and 2 parts acetic acid, and PEI is not included. The remaining operations are the same as in Example 2.

[0099] III. Performance Test Experiments and Results

[0100] To evaluate the effect of mineralization additives on the performance improvement of recycled aggregates, this experiment tested the water absorption, apparent density, and crushing value of the mineralized recycled aggregates. All tests were conducted in accordance with the current national standard and industry specification: GB / T17431.2-2010 "Test Methods for Concrete Aggregates Part 2: Coarse Aggregates". All measurements were performed at least multiple times, and the average value was taken.

[0101] 1. Water absorption rate

[0102] Water absorption rate is used to evaluate the water absorption resistance and porosity improvement effect of mineralized aggregates. The specific operation is as follows: Take samples of the same batch of recycled aggregates after mineralization and before mineralization to measure the water absorption rate. Screen particles with a particle size range of 4.75-9mm. Slowly immerse the dried sample in deionized water, with the water depth ≥20mm above the top of the sample and the water temperature 20±2°C. Let it stand and soak for 24 hours to ensure that the aggregate fully absorbs water. After soaking, take out the sample and let it stand at room temperature for 1-2 minutes. Gently wipe off the free water adhering to the surface with a damp cloth and weigh the saturated surface dry weight (SSD weight). Place the sample in an oven at 105±5°C to dry to constant weight (weigh twice consecutively, with an interval of 2 hours, and the mass change does not exceed 0.2%). Weigh the dry weight and calculate the water absorption rate according to the following formula:

[0103]

[0104] 2. Apparent density

[0105] Apparent density is used to evaluate the overall compactness and volumetric properties of recycled aggregate after mineralization, reflecting the effect of mineralization deposition in filling pores. The specific operation is as follows: Take the same batch of recycled aggregate before and after mineralization (no need to screen the particle size), remove dust and impurities, place the entire batch of aggregate on an electronic balance and weigh the total dry weight W (kg), accurate to 0.01 kg. Select a graduated cylinder or other container, record the container's own weight, and ensure that the inside of the container is clean and free of adhering substances. Slowly pour the aggregate into the container, avoiding aggregate breakage or the formation of irregular accumulation voids. Use the water displacement method or the water displacement method to determine the volume, record the volume of liquid discharged or measure the water level change, and obtain the total aggregate volume V (m3). Calculate the overall apparent density according to the following formula:

[0106]

[0107] 3. Crushing value

[0108] The crushing value is used to evaluate the mechanical strength and compressive properties of recycled aggregates after mineralization, reflecting the improvement effect of mineralization deposition on the compressive strength of aggregates. The specific operation is as follows: Take a mineralized aggregate sample with a particle size of 4.75–9 mm, remove impurities and dust, weigh the initial weight, use a standard crusher, check the instrument's integrity, calibrate the pressure sensor, and set the pressure increase rate to meet the standard requirements. Evenly load the aggregate into the crusher's pressure plate, avoiding aggregate accumulation in one corner to ensure uniform force distribution. Apply pressure slowly according to national or industry standards until the aggregate is crushed. Record the maximum pressure and crushing process. After crushing, sieve the particles to remove powder, and weigh the total weight W of the crushed particles (pressure should be applied slowly during operation to avoid instantaneous impact causing aggregate crushing; crushed particles should be weighed immediately to prevent environmental humidity or moisture from affecting the results). Calculate the crushing value according to the following formula:

[0109]

[0110] 4. Results

[0111] Random samples were taken from untreated recycled aggregates in the raw materials and tested simultaneously with recycled aggregates treated in Examples 2-10 and Comparative Examples 1-7. The test results are shown in Table 2.

[0112] Table 2 Comparison of the performance of recycled aggregates in different groups

[0113] Group Water absorption rate (%) <![CDATA[Apparent density (kg / m 3 ).]]> Crushing value (%) raw and unprocessed 6.80 2495 19.8 Example 2 5.02 2574 16.5 Example 3 4.91 2578 16.3 Example 4 5.13 2572 16.75 Example 5 4.85 2583 16.15 Example 6 4.82 2590 16.0 Example 7 5.12 2566 16.7 Example 8 4.92 2585 16.4 Example 9 4.81 2594 15.95 Example 10 4.75 2595 15.85 Comparative Example 1 5.75 2510 18.4 Comparative Example 2 5.45 2530 17.7 Comparative Example 3 5.35 2534 17.65 Comparative Example 4 5.42 2532 17.8 Comparative Example 5 5.14 2555 17.0 Comparative Example 6 5.22 2553 17.15 Comparative Example 7 5.13 2558 17.0

[0114] As shown in the table, the example group significantly outperformed the comparative group in all performance indicators, demonstrating the significant advantages of the synergistic effect of the three additives. In the experiment, water absorption rate, as the core indicator of aggregate pore filling and hydrophobicity, indicates that the lower the value, the weaker the aggregate's water absorption capacity and the higher the degree to which the pores are filled by calcium carbonate deposition. The water absorption rate of unmineralized aggregate (Comparative Example 1) was approximately 5.75%, reflecting that the pore structure was still loose, and water easily entered the aggregate interior. Single additive treatments (Comparative Examples 2-4) showed slight improvement, with PEI alone reducing the water absorption rate to approximately 5.45%, calcium hydroxide alone to approximately 5.35%, and acetic acid alone to approximately 5.42%, showing that the ability of a single component to improve pore size is limited. The combination of two additives (Comparative Examples 5-7) further reduced the water absorption rate to approximately 5.13%–5.22%, fully demonstrating the synergistic effect of PEI and calcium carbonate. 2+ The synergistic effect between acetic acid activating the aggregate surface, and the further reduction of water absorption rate in the three-adjuvant synergistic system (Examples 2-10) to 4.75%–5.13%, indicates that the three adjuvants work together through different mechanisms to capture CO2 and reduce Ca2+. 2+ The combined effects of generation and pore surface activation significantly enhance pore filling efficiency. In a comprehensive comparison, the water absorption rate of the example group is not only the lowest, but also the values ​​are concentrated and the fluctuations are small, indicating that the system has good controllability and stability for aggregate pore structure.

[0115] In terms of apparent density, the density of the original recycled aggregate is 2495 kg / m³. 3 The density of unmineralized aggregate is approximately 2510 kg / m³. 3 The single-agent treatment slightly increased the yield to 2530–2534 kg / m³. 3 The combined use of two adjuvants has been further improved to 2553-2558 kg / m³. 3 The example group with the synergistic system of the three adjuvants showed the best performance, with an apparent density of 2566–2595 kg / m³. Analysis revealed that the three adjuvants system provides CO2 capture sites through PEI and soluble Ca through calcium hydroxide. 2+ The activation effect of ions and acetic acid on the pore surface makes the mineralization reaction more uniform and complete, and the calcium carbonate deposition more compact, thereby effectively improving the overall density of the aggregate. In addition, extending the mineralization time or appropriately increasing the temperature and CO2 pressure, such as in Example 9 (48-hour mineralization) and Example 10 (hot air circulation drying), can further increase the aggregate density, indicating that the system can still maintain excellent performance under industrial conditions.

[0116] Regarding the crushing value, the unmineralized aggregate had a crushing value of approximately 18.4%, while the single-agent system reduced it to approximately 17.65%–17.8%, the dual-agent combination to approximately 17.0%–17.15%, and the synergistic system of three additives significantly reduced it to 15.85%–16.75%, demonstrating the most significant effect on compressive strength enhancement. Analysis showed that the synergistic system of three additives formed a uniform and dense calcium carbonate deposition network in the aggregate pores, enhancing the internal structural stability of the aggregate and significantly improving its compressive strength. Furthermore, experimental results indicated that an appropriate PEI content could enhance CO2 capture efficiency, and calcium hydroxide provided sufficient Ca... 2+ Ions, acetic acid activate the pore surface and assist calcium carbonate deposition. Under the synergistic effect of the three, the aggregate crushing value is significantly lower than that of single or dual additive systems.

[0117] Further comparative analysis revealed that single additives had limited effect in improving aggregate properties, while the combination of two additives, although exhibiting a certain synergistic effect, was still lower than that of the three-additive system. The water absorption rate of the aggregates obtained by mineralization in Examples 2-10 was concentrated between 4.75% and 5.13%, and the apparent density was between 2566 and 2595 kg / m³. 3 The crushing value was between 15.85% and 16.75%, demonstrating excellent overall performance; while in the comparative groups, the water absorption rate of the dual-agent combination of PEI+Ca(OH)2 or PEI+acetic acid was approximately 5.13% to 5.22%, and the apparent density was approximately 2553 to 2558 kg / m³. 3 The crushing value was approximately 17.0%–17.15%, lower than the three-agent system but higher than the single-agent group and the unmineralized group, indicating that the dual-agent combination can achieve a certain synergistic effect, but it is far less than the overall effect of the three-agent system. The single-agent group showed relatively limited improvement in water absorption, apparent density, and crushing value, indicating that the mechanism of action of a single component is difficult to simultaneously cover pore filling and Ca. 2+ Provides surface activation function.

[0118] In summary, the synergistic system of the three additives has significant advantages in optimizing the pore structure, enhancing density, and improving the mechanical properties of recycled aggregates. It not only significantly reduces water absorption, significantly increases apparent density, and decreases crushing value, but also further optimizes aggregate performance by adjusting the ratio of PEI, calcium hydroxide, and acetic acid, as well as the mineralization time, CO2 pressure, and temperature. Overall, the optimal ratio of industrial mineralization additives is 10 parts PEI, 5 parts calcium hydroxide, and 2 parts acetic acid. The optimal industrial mineralization conditions are: mineralization liquid temperature of 50℃, CO2 pressure in the tower of 0.15MPa, mineralization time of 24h, and hot air circulation drying.

[0119] The mineralization additives and mineralization methods provided in this application not only achieve simultaneous improvement in aggregate performance and carbon sequestration efficiency, but also simplify the wet mineralization process, providing a new green technology solution for the industrial preparation of high-performance recycled aggregates.

Claims

1. A wet mineralization aid for recycled aggregates, characterized in that, It includes the following components by weight: 8-10 parts polyethyleneimine (PEI), 4-6 parts calcium hydroxide, and 1-3 parts acetic acid.

2. The wet mineralization aid according to claim 1, characterized in that, It includes the following components by weight: 10 parts polyethyleneimine (PEI), 5 parts calcium hydroxide, and 2 parts acetic acid.

3. A wet mineralization method for recycled aggregates, characterized in that, The use of the mineralization aid according to claim 1 or 2 includes the following steps: S1. Dissolve the mineralizing agent in water to prepare a mineralizing solution; S2. Immerse the recycled aggregate to be mineralized into the mineralization solution prepared in S1, so that the mineralization solution fully wets the surface and pores of the recycled aggregate. S3. Wet mineralization reaction is carried out in the presence of CO2; S4. After mineralization is completed, the aggregate is dried or used in the next step.

4. The mineralization method according to claim 3, characterized in that, The concentrations of each component in the mineralization solution are as follows: polyethyleneimine 0.5–0.7 g / L, calcium hydroxide 0.27–0.4 g / L, and acetic acid 0.07–0.2 g / L.

5. The mineralization method according to claim 4, characterized in that, The concentrations of each component in the mineralization solution are: polyethyleneimine 0.67 g / L, calcium hydroxide 0.33 g / L, and acetic acid 0.13 g / L.

6. The mineralization method according to claim 3, characterized in that, In S3, the mineralization temperature is 40–60℃, the CO2 pressure is 0.1–0.2 MPa, and the mineralization time is 12–48 h.

7. The mineralization method according to claim 6, characterized in that, In S3, the mineralization temperature is 50℃, the CO2 pressure is 0.15 MPa, and the mineralization time is 24h.

8. An auxiliary mineralization apparatus for implementing the mineralization method according to claim 3, characterized in that, The system includes a tower body, which is equipped with a movable screen, a water tank, a lifting device, an air supply device, and a spray assembly. The movable screen is slidably disposed within the tower body and is used to place aggregates to be mineralized. The water tank is disposed within the tower body and is used to fill the mineralization liquid. The lifting device is connected to the movable screen and is used to drive the movable screen to move up and down. The air supply device is used to provide CO2 into the tower body. The spray assembly is disposed on the tower body and is used to circulate and spray the mineralization liquid in the water tank.

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