A solid waste-based swelling activator and its preparation method

Abstract

This invention relates to the field of low-carbon building materials technology, specifically to a solid waste-based expansive activator and its preparation method. The expansive activator is made from steel slag powder, blast furnace slag powder, fly ash, desulfurized gypsum powder, and modified attapulgite clay powder. Its core innovation lies in a specific two-step mineralization modification of the attapulgite clay: first, an anionic nucleating agent and sodium carbonate are added for the first mineralization step; then, a cationic confinement agent and sodium carbonate are added for the second mineralization step; finally, heat treatment is performed for shaping. This method constructs a stable gradient porous functional layer in situ on the surface of the attapulgite clay. After mixing and pre-hydrating with solid waste raw materials, it can synergistically reduce the water demand of the cementitious system, promote the growth of hydration products to improve early strength, and significantly inhibit drying shrinkage by uniformly distributing the expansive components through anchoring. This invention effectively solves the technical problems of low early strength and poor volume stability in solid waste-based low-carbon cementitious materials.

Description

Technical Field

[0001] This invention relates to the field of low-carbon building materials technology, and in particular to a solid waste-based expandable activator and its preparation method. Background Technology

[0002] In the field of low-carbon building materials, utilizing industrial solid waste (such as steel slag, mineral slag, and fly ash) to partially or completely replace cement clinker is an important technological direction. However, low-clinker or clinker-free cementitious systems generally face technical bottlenecks such as slow hydration, low early strength, and difficulty in controlling volume stability (especially drying shrinkage). To improve the performance of the system, mineral admixtures or additives with specific functions are often introduced.

[0003] Attapulgite clay, due to its unique layered chain structure and abundant surface active sites, has been attempted as a mineral admixture to exert nucleating agent and micro-aggregate filling effects. However, untreated attapulgite clay has significant drawbacks in application: its nanoscale crystal bundles are prone to agglomeration, making dispersion in cementitious materials difficult; its high specific surface area characteristics can significantly increase the water demand of the system, deteriorating workability; at the same time, its surface lacks stability in alkaline hydration environments, and the nucleation sites it provides are random and short-lived, making it difficult to continuously and effectively guide the orderly growth of hydration products, resulting in limited and unstable contribution to early strength development.

[0004] To overcome the aforementioned problems, some studies have attempted to modify the surface of attapulgite clay or directly add nucleating agents such as calcium carbonate. However, simple physical mixing or surface coating is insufficient to construct a stable and robust functional layer on the surface of attapulgite clay. The added calcium carbonate particles have weak bonding with the attapulgite clay matrix and are easily separated during mixing and curing, failing to form a stable composite interface. This limits their nucleation effect and does not significantly mitigate the side effect of reducing the high water demand of attapulgite clay itself. Furthermore, methods that rely solely on organic dispersants or polymers to improve dispersibility often show diminishing effects over time or under the influence of hydration products, failing to provide long-term, stable results.

[0005] In systems involving expanding components, such as calcium sulfoaluminate-based expansion sources introduced to compensate for shrinkage, ensuring the uniform distribution of these components in the slurry and the timely and appropriate generation of expansion stress is a significant challenge. In existing technologies, expanding components are typically simply mixed with cementitious materials. This can lead to localized over-expansion causing stress concentration, or insufficient localized expansion failing to effectively compensate for shrinkage, thus increasing the risk of system cracking. Therefore, in pursuing the dual goals of high early strength and high volumetric stability in low-carbon cementitious materials, how to synergistically address the three interrelated yet often contradictory issues of water demand, nucleation stability, and expansion uniformity at the molecular / microscopic scale through material design has become a critical challenge in this field. Summary of the Invention

[0006] In view of this, the purpose of this invention is to propose a solid waste-based expansion activator and its preparation method, so as to overcome the problems of high water demand, unstable nucleation effect, and uneven distribution of expansion components leading to shrinkage cracking risk in low-carbon cementitious materials caused by the direct use of attapulgite clay or its simple composites in the prior art.

[0007] To achieve the above objectives, the present invention provides a solid waste-based expansion activator, which is made from the following raw materials by pre-hydration with water, drying and grinding: steel slag powder, blast furnace slag powder, fly ash, desulfurized gypsum powder and attapulgite clay modified powder. Preferably, the mass ratio of the steel slag powder, blast furnace slag powder, fly ash, desulfurized gypsum powder, and attapulgite clay modified powder is 400:300:200:50:50.

[0008] Furthermore, the modified attapulgite clay powder is prepared by the following steps: attapulgite clay and dispersant are dispersed in deionized water, calcium salt is added and the pH is adjusted to 11-13; an anionic stabilizing regulator is added to the resulting system, followed by a first sodium carbonate aqueous solution for the first step of mineralization, then a cation confinement regulator is added, followed by a second sodium carbonate aqueous solution for the second step of mineralization; subsequently, the resulting product is filtered, washed, dried and heat-treated for shaping.

[0009] Preferably, the mass ratio of the attapulgite clay, dispersant, deionized water, calcium salt, anion stabilizer, first sodium carbonate aqueous solution, cation confinement regulator, and second sodium carbonate aqueous solution is 50:5:500:30-35:5-6:112:5:110; wherein, the first sodium carbonate aqueous solution is prepared by anhydrous sodium carbonate and deionized water at a weight ratio of 12:100, and the second sodium carbonate aqueous solution is prepared by anhydrous sodium carbonate and deionized water at a weight ratio of 10:100.

[0010] Preferably, the attapulgite clay has a mesh size of 1250.

[0011] Preferably, the specific surface area of ​​the steel slag powder is 400-450 m². 2 / kg.

[0012] Preferably, the slag powder is grade S95 and the fly ash is grade II fly ash.

[0013] Preferably, the desulfurized gypsum powder contains ≥93% calcium sulfate dihydrate, has a particle size not exceeding 92μm, and more than 80% of the particles are in the range of 30-60μm.

[0014] Preferably, the dispersant is sodium lignosulfonate or naphthalene sulfonate formaldehyde condensate.

[0015] Preferably, the calcium salt is calcium chloride dihydrate or calcium acetate monohydrate.

[0016] Preferably, the anion stabilizing regulator is polyacrylic acid or polyaspartic acid; the cation confinement regulator is branched polyethyleneimine or polydiallyldimethylammonium chloride.

[0017] Preferably, the weight-average molecular weight of the anion stabilizing regulator is 1000-3000.

[0018] Preferably, the weight-average molecular weight of the cation confinement regulator is 20,000-40,000.

[0019] Preferably, the heat treatment is performed by heating the dried product to 350°C at a rate of 2°C / min in air and holding it at that temperature for 120 min.

[0020] Preferably, the water addition and prehydration is performed by: first dry mixing steel slag powder, blast furnace slag powder, fly ash, desulfurized gypsum powder and attapulgite clay modified powder, then adding deionized water to form uniform wet granules, sealing and curing at 40°C for 180 min, then drying at 60°C to constant weight and grinding until all of them pass through a 75 μm sieve.

[0021] Furthermore, the present invention also provides a method for preparing a solid waste-based swelling activator, comprising the following steps: (1) Add attapulgite clay and dispersant to deionized water for dispersion, add calcium salt and adjust pH to 12; (2) In the system obtained in step (1), first add an anion-stabilizing regulator, then add a first sodium carbonate aqueous solution for the first step of mineralization, then add a cation-confining regulator, and then add a second sodium carbonate aqueous solution for the second step of mineralization. (3) The product obtained in step (2) is filtered, washed, dried and heat-treated to shape it, so as to obtain attapulgite clay modified powder; (4) By mass fraction, steel slag powder, blast furnace slag powder, fly ash, desulfurized gypsum powder and attapulgite clay modified powder obtained in step (3) are mixed, pre-hydrated with water, and then dried and ground to obtain solid waste-based expansion activator.

[0022] Preferably, in step (1), after adding calcium salt, the mixture is stirred at 30°C for 30 min, and the pH is adjusted to 12 with calcium hydroxide and then stirred for another 60 min; in step (2), after heating the system to 40°C, an anion stabilizing regulator is added and stirred for 30 min, and then the first sodium carbonate aqueous solution is added dropwise within 10 min and stirred for another 20 min; then, while maintaining the temperature at 40°C, a cation confinement regulator is added and stirred for 10 min, and then the second sodium carbonate aqueous solution is added dropwise within 20 min and stirred for another 40 min.

[0023] The beneficial effects of this invention are: First, the porous carbonate functional layer constructed and shaped in situ on the surface of attapulgite clay effectively reduced the specific surface energy of attapulgite particles and alleviated crystal bundle aggregation, thereby significantly reducing the negative impact of its introduction on the water demand of the cementing system and improving the fluidity and workability of the slurry. This inorganic functional layer remained structurally stable in the subsequent alkaline environment, providing numerous durable and robust nucleation sites for the deposition of hydration products.

[0024] Secondly, a specific mineralization process, involving first stabilizing the nuclei with polyacrylic acid and then confining them with branched polyethyleneimine, was employed to form a confined porous layer with a gradient structure on the surface of attapulgite. Even after heat treatment to remove organic matter, this structure retains abundant porosity and interfacial characteristics dominated by the inorganic framework, thus continuously exerting a strong nucleation-inducing effect and physical anchoring effect. This effectively promotes the uniform and dense growth of hydration products, especially early-stage hydration products, thereby enhancing the early mechanical strength of the material.

[0025] Furthermore, the modified attapulgite clay powder is embedded in a micro-hydration process of solid waste expansion components, primarily steel slag powder and mineral slag powder, allowing the modified powder to be in-situ anchored to the expansion component precursors (such as ettringite seed crystals). This pre-assembly mechanism ensures a more uniform spatial distribution of the expansion source within the final cementitious material matrix, enabling the expansion stress to be released gradually over a wider range, thereby significantly suppressing the tendency for drying shrinkage and cracking caused by uneven local expansion.

[0026] In summary, the solution provided by this invention starts with interface engineering and process control, enabling modified attapulgite clay to simultaneously serve as an efficient water-reducing component, a stable nucleation center, and a distribution regulator of the expansion phase. Ultimately, this achieves a synergistic improvement in low water consumption, high early strength, and excellent volume stability in a low-carbon cementitious material system. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0028] Raw material source and model: Attapulgite clay: Attapulgite / palmitite powder sold by Hebei Yayang Lithium Spodumene Co., Ltd., specification 1250 mesh, in powder form; Sodium lignosulfonate: Tokyo Chemical Industry Co., Ltd., product code L0098, methoxy content 5%-7%; Naphthalene sulfonate formaldehyde condensate: FDN type naphthalene-based high-efficiency water-reducing agent produced by Jiangsu Subote New Material Co., Ltd., brown powder, solid content ≥92%, density approximately 0.45 g / cm³. 3The main component is sodium salt of naphthalenesulfonic acid formaldehyde condensate, suitable for cement dispersion systems; Steel slag powder: Produced by Weifang Special Steel Group Co., Ltd., with a particle size D50 of approximately 10-15μm and a specific surface area of ​​approximately 400-450m². 2 / kg; Slag powder: Weifang Special Steel Group Co., Ltd. slag powder product S95 grade, specific surface area approximately 420m² 2 / kg; Fly ash: Grade II fly ash from Rizhao Steel Holding Group Co., Ltd., with a specific surface area of ​​approximately 350 m² / kg; 2 / kg; Desulfurized gypsum powder: Desulfurization by-product gypsum from Huaneng Group power plant, the main component is calcium sulfate dihydrate, the calcium sulfate dihydrate content is ≥93%, the particle size does not exceed 92μm and more than 80% of the particles are in the range of 30-60μm.

[0029] Example 1: Step S1: Add 500g of deionized water to a mixing container, then add 50g of attapulgite clay and 5g of sodium lignosulfonate in sequence. Stir at 2000rpm for 10min at 25℃, then switch to 600rpm for 20min. Finally, disperse the mixture with ultrasonic at 40kHz for 20min to obtain a dispersion slurry. Step S2: Heat the slurry obtained in step S1 to 30°C and stir at 600 rpm. Separately, dissolve 30g of calcium chloride dihydrate in 200g of deionized water to obtain a calcium salt solution. Add the calcium salt solution dropwise to the dispersed slurry and stir for 30 min. Then add calcium hydroxide to adjust the pH to 12 and continue stirring for 60 min. Step S3: Heat the slurry obtained in step S2 to 40°C and stir at 600 rpm. Add 10g of polyacrylic acid solution (weight average molecular weight 2000, 50wt% aqueous solution) and stir for 30 min. Then dissolve 12g of anhydrous sodium carbonate in 100g of deionized water to obtain sodium carbonate solution A. Add sodium carbonate solution A dropwise over 10 min and continue stirring for 20 min. Step S4: Keep the slurry obtained in step S3 at 40°C and stir at 600 rpm. Separately, add 5g of branched polyethyleneimine (weight average molecular weight 25000) to 45g of deionized water to prepare a polyethyleneimine solution. First, add 50g of polyethyleneimine solution and stir for 10min. Then, dissolve 10g of anhydrous sodium carbonate in 100g of deionized water to obtain sodium carbonate solution B. Add sodium carbonate solution B dropwise over 20min and continue stirring for 40min. Step S5: Filter the slurry obtained in step S4 to obtain a solid filter cake. First, wash the filter cake multiple times with deionized water. Then, take 10g of deionized water to prepare 1g of silver nitrate solution as a test solution. Take 1mL of the last washing filtrate and mix it with 1mL of silver nitrate solution until no white precipitate is produced, which is the washing endpoint. Step S6: The wet solid obtained in step S5 is dried at 105°C to constant weight to obtain dry powder. The dry powder is heated to 350°C at 2°C / min in air atmosphere and kept at that temperature for 120 min, and then cooled naturally to obtain attapulgite clay modified powder. Step S7: Weigh 400g of steel slag powder, 300g of blast furnace slag powder, 200g of fly ash, 50g of desulfurized gypsum powder, and 50g of attapulgite clay modified powder. First, dry mix for 5 minutes, then add 80g of deionized water and stir at 300 rpm for 5 minutes to form uniform wet granules. Then seal and let stand at 40℃ for 180 minutes. After that, dry at 60℃ to constant weight and grind until all of them pass through a 75μm sieve to obtain a pre-hydrated solid waste-based expansion activator semi-finished product. The obtained semi-finished product is then dry-milled again by ball milling for 10 minutes and homogenized by passing through a 75μm sieve to obtain a solid waste-based expansion activator.

[0030] Example 2: The difference from Example 1 is that in step S1, 5g of sodium lignosulfonate is replaced with 5g of naphthalene sulfonate formaldehyde condensate, while keeping 50g of attapulgite clay and 500g of deionized water unchanged; the remaining steps are the same as in Example 1.

[0031] Example 3: The difference from Example 1 is that in step S2, 30g of calcium chloride dihydrate is replaced with 35g of calcium acetate monohydrate; the remaining steps are the same as in Example 1.

[0032] Example 4: The difference from Example 1 is that in step S3, 10g of polyacrylic acid solution was replaced with 6g of polyaspartic acid solid (weight average molecular weight 2000) and dissolved in 54g of deionized water before being added; in step S4, 5g of branched polyethyleneimine was replaced with 5g of polydiallyldimethylammonium chloride (weight average molecular weight 30000) and diluted with deionized water to 50g before being added; the remaining steps are the same as in Example 1.

[0033] Example 5: The difference from Example 1 is that the amount of polyacrylic acid solution added in step S3 is adjusted from 10g to 14g; the amount of branched polyethyleneimine in step S4 remains unchanged at 5g; the remaining steps are the same as in Example 1.

[0034] Example 6: The difference from Example 1 is that in step S3, polyacrylic acid is replaced with solid polyacrylic acid with an average molecular weight of about 100,000. 4g of solid polyacrylic acid is dissolved in 96g of deionized water and then added. In step S4, 5g of branched polyethyleneimine is kept unchanged. The remaining steps are the same as in Example 1.

[0035] Comparative Example 1: The difference from Example 1 is that in step S7, 50g of attapulgite clay modified powder is replaced with 50g of attapulgite clay; the other conditions are the same as in Example 1.

[0036] Comparative Example 2: The difference from Example 1 is that in step S6, after drying the wet solid obtained in step S5 to constant weight at 105°C to obtain dried powder, 50g of the dried powder is directly used in step S7, without raising the temperature to 350°C at 2°C / min and holding it at that temperature for 120min in air; the remaining conditions are the same as in Example 1. The solid waste-based expanding activator of Comparative Example 2 is prepared according to the above steps.

[0037] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that in step S3, instead of adding 10g of polyacrylic acid solution, 10g of deionized water is added; the other conditions are the same as in Example 1. The solid waste-based swelling activator of Comparative Example 3 was prepared according to the above steps.

[0038] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that in step S4, instead of adding 50g of polyethyleneimine solution, 50g of deionized water is added; the other conditions are the same as in Example 1. The solid waste-based swelling activator of Comparative Example 4 was prepared according to the above steps.

[0039] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is as follows: In step S3, 50g of polyethyleneimine solution from step S4 is added in advance and stirred for 10 minutes, then 12g of anhydrous sodium carbonate is dissolved in 100g of deionized water to obtain sodium carbonate solution A, and sodium carbonate solution A is added dropwise over 10 minutes while stirring for another 20 minutes; In step S4, 10g of polyacrylic acid solution is added and stirred for 30 minutes, then 10g of anhydrous sodium carbonate is dissolved in 100g of deionized water to obtain sodium carbonate solution B, and sodium carbonate solution B is added dropwise over 20 minutes while stirring for another 40 minutes; the remaining conditions are the same as in Example 1.

[0040] Comparative Example 6: The difference between Comparative Example 6 and Example 1 is that in step S4, instead of adding 50g of polyethyleneimine solution first, 10g of anhydrous sodium carbonate is dissolved in 100g of deionized water to obtain sodium carbonate solution B. Sodium carbonate solution B is then added dropwise over 20 minutes while stirring for another 40 minutes. Then, 50g of polyethyleneimine solution is added and stirred for 10 minutes. The remaining conditions are the same as in Example 1. The solid waste-based expanding activator of Comparative Example 6 is prepared according to the above steps.

[0041] Performance testing: P·O 42.5 ordinary Portland cement was used as the reference cementitious material. For the neat mortar samples with standard consistency and water content, 460g of ordinary Portland cement and 40g of the tested solid waste-based expansive activator were weighed out for each group. The mixture was first dry-mixed for 120s, and then deionized water was added and stirred according to the test specifications. For the mortar samples used for tests of mortar flowability, mortar mechanical properties, and natural drying shrinkage, 414g of ordinary Portland cement, 36g of the tested solid waste-based expansive activator, 1350g of ISO standard sand, and 225g of deionized water were weighed out for each group. The mixture was then mixed according to the specified procedure and molded.

[0042] Standard consistency water consumption: The test was conducted in accordance with GB / T 1346-2024. The standard consistency water consumption was determined using a Vicat apparatus. The amount of water added when the test needle sinks to 6 mm from the bottom plate was taken as the standard consistency water consumption. Each sample was tested in parallel 3 times, and the arithmetic mean was taken as the final result.

[0043] Mortar flowability: The test was conducted according to GB / T 2419-2005. The mortar was placed in a flowability truncated cone mold, vibrated and then lifted. The mold was then lifted and 25 jumps were completed on a jumping table within 25 seconds. The two mutually perpendicular diameters after the mortar flow were measured, and the average value was taken as the mortar flowability. Each sample was tested in parallel 3 times, and the arithmetic mean was taken as the final result.

[0044] Mechanical properties of mortar: Tested according to GB / T 17671-2021. The specimens were molded in 40mm×40mm×160mm molds. Three specimens were prepared for each age and cured according to standard. The flexural strength was tested first at 3d, 7d and 28d, and then the compressive strength was tested with 6 half prisms. The arithmetic mean of the results was taken.

[0045] Natural drying shrinkage: The test was conducted according to JGJ / T 70-2009. The specimens were molded in a 40mm×40mm×160mm mold with a length measuring head. After molding, the specimens were left to stand at 20℃ for 4 hours and the surface was smoothed. Then, they were placed in an environment with a temperature of (20±2)℃ and a relative humidity of more than 90% for 7 days before demolding. After demolding, the specimens were placed in an environment with a temperature of (20±2)℃ and a relative humidity of (60±5)% for 4 hours to measure the initial length. The length change was measured at 7 days and 28 days. The natural drying shrinkage value was calculated based on the initial length. Three specimens were prepared for each sample, and the arithmetic mean of the results was taken.

[0046] Table 1 Performance Test Results

[0047] Data Analysis: As can be seen from the data in Table 1, the solid waste-based expansive activator prepared by this invention maintains good mortar workability while keeping the standard consistency water requirement low, and ensures stable growth of flexural and compressive strength with age, while effectively suppressing natural drying shrinkage. This indicates that the porous carbonate / carbonate functional layer constructed in situ on the surface of attapulgite clay can still retain a stable inorganic nucleation interface after low-temperature heat treatment. After entering the prehydration system composed of steel slag powder, blast furnace slag powder, fly ash, and desulfurized gypsum powder, it can promote more uniform generation of hydration products and improve particle packing. At the same time, the modified powder forms in-situ anchorage of the expansive components during the micro-water prehydration process, making the spatial distribution of the expansion effect more balanced. This is beneficial to the early strength development of low-carbon cementitious materials and also to the long-term requirements of volume stability for new wall materials.

[0048] As can be seen from the data in Example 1 and Comparative Example 1 in Table 1, after replacing the modified attapulgite clay powder with unmodified attapulgite clay, the standard consistency water requirement increased significantly, the mortar fluidity decreased, and both strength development and shrinkage control were adversely affected. The main reason is that attapulgite clay without surface mineralization and low-temperature setting still maintains strong crystal bundle aggregation and high specific surface area characteristics, which both competes for free water and makes it difficult to provide a continuous and stable nucleation interface, leading to uneven distribution of expansion components during prehydration. Therefore, the in-situ construction of porous carbonate / carbonate functional layers is not simply a matter of surface coating, but rather a key process that balances reducing water demand, stabilizing nucleation, and achieving uniform expansion.

[0049] As can be seen from the data in Table 1 for Example 1 and Comparative Example 2, if low-temperature heat treatment is lacking after surface mineralization for shaping, the overall performance is lower than that of Example 1, and the retention of shrinkage inhibition is insufficient. It is speculated that this is because the unshaped surface structure is more prone to local rearrangement or loosening during subsequent alkaline environment and micro-water pre-hydration processes, making it difficult to maintain a continuous porous inorganic interface over a long period. This weakens the uniformity of nucleation, interface anchoring, and expansion release. This indicates that low-temperature heat treatment is not an auxiliary step, but a crucial step in transforming the aforementioned mineralized structure into a stable functional layer.

[0050] As can be seen from the data in Table 1 for Example 1 and Comparative Example 3, simply omitting polyacrylic acid adversely affects the system's water consumption, fluidity, strength, and shrinkage. The main reason is that polyacrylic acid plays a crucial role in stabilizing the initial crystal nuclei and regulating early epitaxial growth during the initial mineralization process. Without this step, carbonates are more likely to precipitate disorderly or form coarse, discrete deposits, resulting in insufficient continuity of the subsequently formed functional layers. Therefore, the role of polyacrylic acid is not merely to introduce organic components, but to lay the structural foundation for subsequent confined growth and is one of the prerequisites for obtaining a stable nucleation interface.

[0051] As can be seen from the data in Table 1 for Example 1 and Comparative Example 4, while the system retains polyacrylic acid but lacks branched polyethyleneimine, it is still superior to the unmodified or unstructured scheme. However, it does not reach the balanced level of Example 1, especially in terms of shrinkage control and later strength. The reason for this is likely that while the initial nucleation stage can generate a finer initial mineralization layer, without subsequent charge reversal and confined growth, the outer structure cannot form a gradient distribution, and the interface anchoring and pore structure control are insufficient, resulting in the presence of crystal nuclei but no complete functional layer. Therefore, with only initial nucleation and lacking subsequent confinement, it is difficult to obtain the comprehensive performance shown in Example 1, indicating that the two-step mineralization is not a simple addition but rather involves an amplification effect.

[0052] As can be seen from the data in Table 1 for Examples 1, 5, and 6, the performance significantly decreased when the branched polyethyleneimine was added earlier or after the second stage of carbonate addition. The decrease was even more pronounced in the case of a completely reversed addition order. This indicates that the process of stabilizing the polyacrylic acid nucleus first and then confining it with branched polyethyleneimine is not an arbitrary, interchangeable parallel relationship, but rather a coupled process with strict timing requirements. If the cation-dominated interface is formed first, it easily interferes with the uniform formation of the preceding carbonate nuclei; if branched polyethyleneimine is added later, it is more likely to remain adsorbed on the surface, making it difficult to construct a continuous gradient-confined porous layer. Therefore, the order set in this invention produces a synergistic effect, demonstrating a significant structural advantage of 1+1 greater than 2.

[0053] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A solid waste-based swelling activator, characterized in that, It is made from the following raw materials through prehydration with water, drying and grinding: steel slag powder, blast furnace slag powder, fly ash, desulfurized gypsum powder and attapulgite clay modified powder; The modified attapulgite clay powder is prepared by the following steps: attapulgite clay and dispersant are dispersed in deionized water, calcium salt is added and the pH is adjusted to 11-13; an anionic stabilizing regulator is added to the resulting system, followed by a first sodium carbonate aqueous solution for the first step of mineralization, then a cation confinement regulator is added, followed by a second sodium carbonate aqueous solution for the second step of mineralization; subsequently, the resulting product is filtered, washed, dried and heat-treated for shaping. The anion stabilizing regulator is polyacrylic acid or polyaspartic acid; the cation confinement regulator is branched polyethyleneimine or polydiallyldimethylammonium chloride.

2. The solid waste-based swelling activator according to claim 1, characterized in that, The mass ratio of the steel slag powder, blast furnace slag powder, fly ash, desulfurized gypsum powder, and attapulgite clay modified powder is 400:300:200:50:

50.

3. The solid waste-based swelling activator according to claim 1, characterized in that, The attapulgite clay has a mesh size of 1250.

4. The solid waste-based swelling activator according to claim 1, characterized in that, The specific surface area of ​​the steel slag powder is 400-450 m². 2 / kg; the slag powder is grade S95; the fly ash is grade II fly ash; the desulfurized gypsum powder contains ≥93% calcium sulfate dihydrate, with a particle size not exceeding 92μm and more than 80% of the particles having a particle size in the range of 30-60μm.

5. The solid waste-based swelling activator according to claim 1, characterized in that, The dispersant is sodium lignosulfonate or naphthalene sulfonate formaldehyde condensate.

6. The solid waste-based swelling activator according to claim 1, characterized in that, The calcium salt is calcium chloride dihydrate or calcium acetate monohydrate.

7. The solid waste-based swelling activator according to claim 1, characterized in that, The weight-average molecular weight of the anion-stabilizing regulator is 1000-3000; the weight-average molecular weight of the cation-confining regulator is 20000-40000.

8. The solid waste-based swelling activator according to claim 1, characterized in that, The heat treatment is performed by heating the dried product to 350°C at a rate of 2°C / min in air and holding it at that temperature for 120 min.

9. A method for preparing a solid waste-based swelling activator according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Add attapulgite clay and dispersant to deionized water for dispersion, add calcium salt and adjust pH to 12; (2) In the system obtained in step (1), first add an anion-stabilizing regulator, then add a first sodium carbonate aqueous solution for the first step of mineralization, then add a cation-confining regulator, and then add a second sodium carbonate aqueous solution for the second step of mineralization. (3) The product obtained in step (2) is filtered, washed, dried and heat-treated to shape it, so as to obtain attapulgite clay modified powder; (4) By mass fraction, steel slag powder, blast furnace slag powder, fly ash, desulfurized gypsum powder and attapulgite clay modified powder obtained in step (3) are mixed, pre-hydrated with water, and then dried and ground to obtain solid waste-based expansion activator.

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