Composite micro-nano active slurry activated solid waste-based cementitious material and preparation method thereof

Abstract

This invention discloses a composite micro-nano active slurry for activating solid waste-based cementitious materials and its preparation method, aiming to solve the problems of slow reaction rate and low early strength in the ternary solid waste-based cementitious system of steel slag-blast furnace slag-gypsum. By mass percentage, the cementitious components include 20-35% steel slag, 45-65% blast furnace slag, and 8-20% desulfurized gypsum; and externally added 0.2-0.8% polyaluminum chloride and 2.3-9% composite micro-nano active slurry, accounting for 2.3% of the total mass of the cementitious components. The composite micro-nano active slurry is obtained by co-calcining alum-halothite composite, calcium sulfoaluminate, and calcium hydroxide in an aqueous medium through wet milling, and is added to the cementitious system as a whole without solid-liquid separation. The composite micro-nano active slurry of this invention works synergistically with polyaluminum chloride to improve the early and later strength of the solid waste-based cementitious material.

Description

Technical Field

[0001] This invention relates to the fields of solid waste resource utilization and cementitious materials technology, specifically to a composite micro-nano active slurry activated solid waste-based cementitious material and its preparation method. Background Technology

[0002] Steel slag, blast furnace slag, and desulfurized gypsum are all bulk solid wastes generated during industrial production. A ternary solid waste-based cementitious system based on steel slag, blast furnace slag, and gypsum can reduce cement clinker usage and improve the resource utilization level of solid waste. However, the active components of steel slag and blast furnace slag in this ternary system have slow dissolution rates, and gypsum mainly provides a sulfate environment and is difficult to initiate a rapid hydration reaction independently. This results in a slow reaction rate, insufficient early hydration product formation, and low early strength, limiting its application in applications requiring early strength, such as road base courses, repair mortars, and grouting materials.

[0003] To improve the early reaction rate of the aforementioned ternary system, existing methods typically involve adding activating components such as calcium sulfoaluminate or sulfoaluminate cement, calcium hydroxide, silicate cement clinker, and polyaluminum chloride. However, the problem is that while adding sulfoaluminate cement or cement clinker alone can improve strength at some ages, the increase is limited by the dosage and clinker ratio; adding polyaluminum chloride alone significantly improves later-age strength but has limited effect on early-age strength; polyaluminum sulfate and polyaluminum chloride usually exhibit a certain degree of salt activation and flocculation assistance, making it difficult to simultaneously address the problems of slow early-age reaction, uneven product distribution, and insufficient structural density in the steel slag-slag-gypsum system. Therefore, there is an urgent need for a composite activation method that can significantly improve the early reaction rate and early-age strength while maintaining low clinker and high solid waste utilization rates. Summary of the Invention

[0004] The purpose of this invention is to address the problems of slow reaction rate and low early strength in the ternary solid waste-based cementitious system of steel slag-blast furnace slag-gypsum, as well as the limited strengthening effect of using sulfoaluminate cement, cement clinker, calcium hydroxide, or polyaluminum chloride alone. This invention provides a composite micro-nano activated slurry-based cementitious material. This material combines polyaluminum chloride with a composite micro-nano activated slurry, and restricts calcium hydroxide to the wet milling activation stage, allowing it to primarily function as an alkaline regulating component to promote the release of active Si / Al species from calcined halloysite, rather than simply as a calcium supplement filler in the cementitious system.

[0005] This invention first co-calcines alum and halloysite to form a co-calcined alum-haloysite composite, then wet-mills the co-calcined alum-haloysite composite with calcium sulfoaluminate and calcium hydroxide in an aqueous medium, thereby obtaining a composite micro / nano active slurry. During the wet milling process, the calcined alum component provides active aluminum sulfoaluminate components; the calcined halloysite provides active aluminum silicate components while retaining some fibrous or tubular framework; and the calcium sulfoaluminate undergoes early hydration in the wet milling aqueous phase.

[0006] Compared to adding calcium sulfoaluminate, sulfoaluminate cement, calcium hydroxide, cement clinker, or polyaluminum chloride alone, this invention utilizes the synergistic effect of polyaluminum chloride and a composite micro / nano active slurry. Before entering the steel slag-blast furnace gypsum ternary system, the composite micro / nano active slurry already forms well-dispersed micro / nano composite particles, active sulfoaluminate components, active silica-alumina components, and a fibrous or tubular halloysite framework. After the slurry is added to the cementing system as a whole, the hydration products can grow along the halloysite framework and its reaction interface, promoting the interweaving and connection of crystal-gel products, thereby improving the early strength, later strength, and structural density of the material.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: Composite micro-nano active slurry activates solid waste-based cementitious materials, comprising the following gel components by mass percentage: 20-35% steel slag, 45-65% blast furnace slag, 8-20% desulfurized gypsum; and externally incorporated polyaluminum chloride and composite micro-nano active slurry; The dosage of polyaluminum chloride is 0.2-0.8% of the total mass of the gelling components, and the dosage of composite micro-nano active slurry is 2.3-9% of the total mass of the gelling components. The composite micro-nano active slurry is obtained by wet milling co-calcined alum-haloite composite, calcium sulfoaluminate and calcium hydroxide in an aqueous medium. The composite micro-nano active slurry is added to the gelling components as a whole without solid-liquid separation.

[0008] Furthermore, the co-calcined alum-haloyite composite is obtained by mixing alum and halloyite at a mass ratio of 1:0.5-3 and then co-calcining them at 650-800℃ for 0.5-3 hours.

[0009] Within the calcination temperature range of 650-800℃, halloysite can be fully dehydroxylated and transformed into an amorphous aluminosilicate phase with high reactivity. At the same time, alum can be dehydrated and effectively composite modified with halloysite. When the temperature is below 650℃, halloysite is not fully dehydroxylated, and the composite has low activity. When the temperature is above 800℃, sulfate decomposition, sintering or crystallization of active components are likely to occur, resulting in decreased reactivity and increased energy consumption.

[0010] Furthermore, the mass ratio of alum to halloysite is 1:1-2, and the calcination temperature is 700-760℃; the halloysite is fibrous or tubular halloysite.

[0011] Further, the co-calcined alum-haloite composite, calcium sulfoaluminate, calcium hydroxide and water are mixed and wet-milled for 10-90 min to obtain a composite micro-nano active slurry; The water-to-solid mass ratio during wet grinding is 0.4-2.0:1, the mass ratio of grinding balls to solid materials is 5:1-20:1, the grinding speed is 200-600 r / min, and the D50 of the solid particles in the slurry after wet grinding is 300-800 nm, the average particle size is 0.5-1.0 μm, and the D90 is not greater than 2 μm.

[0012] During wet milling, at least some of the soluble components in the co-calcined alum-haloyite composite enter the aqueous phase. Under alkaline conditions and mechanical action, the calcined halloyite releases active silica-alumina components, and calcium sulfoaluminate undergoes early hydration, forming a slurry containing active components and micro / nano composite particles. Therefore, the composite micro / nano active slurry contains active sulfoalumina components provided by alum, active silica-alumina components provided by calcined halloyite, and an incompletely dissolved fibrous or tubular halloyite framework.

[0013] Furthermore, the amount of co-calcined alum-halothite composite is 0.8-2.5% of the total mass of the cementing components, the amount of calcium sulfoaluminate is 1-5% of the total mass of the cementing components, and the amount of calcium hydroxide is 0.5-1.5% of the total mass of the cementing components.

[0014] Furthermore, in the composite micro-nano active slurry, the amount of calcined alum-haloite composite is 1.2-2.2% of the total mass of the cementitious components, the amount of calcium sulfoaluminate is 2-4% of the total mass of the cementitious components, and the amount of calcium hydroxide is 0.6-1.2% of the total mass of the cementitious components.

[0015] Furthermore, in the composite micro-nano active slurry, the amount of calcined alum-haloite composite is 1.5% of the total mass of the cementitious components, the amount of calcium sulfoaluminate is 3% of the total mass of the cementitious components, and the amount of calcium hydroxide is 1.0% of the total mass of the cementitious components.

[0016] Furthermore, the mass ratio of steel slag, blast furnace slag, and desulfurized gypsum is 25-32:52-60:10-18; the dosage of polyaluminum chloride is 0.3-0.6% of the total mass of the cementitious components.

[0017] Furthermore, the mass ratio of steel slag, blast furnace slag, and desulfurized gypsum is 30:55:15; the dosage of polyaluminum chloride is 0.5% of the total mass of the cementitious components.

[0018] The alum is potassium alum, ammonium alum, or a combination thereof, preferably potassium alum. The alum contains aluminum and sulfate ions, and after calcination, it loses its water of crystallization to form anhydrous or low-hydrated sulfate active components. In a wet milling medium, its soluble components can release aluminum salt and sulfate active ions, effectively providing the system with active aluminum sulfide components, thus providing reactants for the formation of ettringite, aluminum-containing hydration products, and sulfoaluminate hydration products.

[0019] Halloysite is a natural hydrated aluminosilicate mineral, preferably in fibrous, tubular, or short fibrous morphology, and its chemical composition includes Al, Si, O, and structural hydroxyl groups. After calcination at 650-800℃, halloysite undergoes dehydroxylation and partial amorphization, forming a metahaloysite or amorphous aluminum-silica phase with high alkali solubility. This calcined halloysite more readily releases active silica-alumina components in the alkaline environment provided by calcium hydroxide; simultaneously, the incompletely dissolved fibrous or tubular framework can act as an interfacial bonding reinforcement and micro-filler.

[0020] The calcium sulfoaluminate can be calcium sulfoaluminate clinker, the calcium sulfoaluminate phase in sulfoaluminate cement, or a mineral component rich in calcium sulfoaluminate. In this invention, calcium sulfoaluminate from the above-mentioned different sources all serve to provide calcium ions, aluminate ions, and sulfate ions to generate ettringite, and their activation function on the cementitious system is essentially the same.

[0021] In this invention, calcium hydroxide primarily serves as an alkaline regulating component during the wet milling stage. Its function is to increase the pH value of the wet milling slurry, promote the breaking of the Si-O-Al structure and the dissolution of active Si / Al in calcined halloysite, and simultaneously provide a suitable alkaline environment for the early hydration of calcium sulfoaluminate and the formation of ettringite crystal nuclei.

[0022] The polyaluminum chloride is either solid or liquid. The polynuclear hydroxyaluminum species in the polyaluminum chloride can synergistically react with sulfate active ions, active Si / Al species in the wet grinding slurry, and Ca, Si, and Al components in the steel slag-blast furnace gypsum system.

[0023] The mechanism of action of this invention is as follows: First, the calcined alum component in the co-calcined alum-haloyite composite releases aluminum salt and sulfate active ions in the wet milling aqueous phase, providing active sulfoaluminate components. Second, calcium hydroxide maintains the alkaline environment of the wet milling process and promotes the dissolution of active silica-aluminate components in the amorphous aluminum-silicon phase formed after the dehydroxylation of calcined halloyite under mechanical milling. Third, calcium sulfoaluminate undergoes early hydration in the aluminum-containing, sulfate-containing, and alkaline aqueous phase, forming dispersed ettringite crystal nuclei.

[0024] When the composite micro-nano active slurry is added to the cementing component (steel slag-blast furnace slag-desulfurized gypsum system) without solid-liquid separation, the ettringite crystal nuclei in the slurry can lower the nucleation energy barrier of hydration products and accelerate the precipitation of early hydration products. The active silica-alumina components participate in the formation of C-(A)-SH gel, hydrated calcium aluminosilicate gel, and aluminum-containing gel structures. The incompletely dissolved fibrous or tubular halloysite framework provides bridging and micro-filling effects. Since halloysite itself continues to dissolve in an alkaline environment, its surface and the vicinity of the dissolution interface have high Si and Al concentrations, thus it is tightly bound to the generated ettringite crystals and hydrated calcium aluminosilicate gel, which helps to improve the matrix density and mechanical properties.

[0025] A method for preparing composite micro / nano-active slurry-activated solid waste-based cementitious materials includes the following steps: The co-calcined alum-haloite composite, calcium sulfoaluminate and calcium hydroxide were wet-milled together in water to obtain a composite micro-nano active slurry. The amount of water used in the wet milling was included in the total mixing water of the cementitious material. Steel slag, desulfurized gypsum and slag are mixed to obtain a cementitious component; The obtained composite micro-nano active slurry was added to the obtained gelling component without solid-liquid separation, and mixing water was added to the required total mixing water volume. The mixture was stirred evenly to obtain solid waste-based gelling material. The total mixing water volume is determined according to GB / T 17671 standard or target performance.

[0026] Compared with the prior art, the present invention has the following beneficial effects: This invention differs from the conventional approach of simply dry-mixing calcium hydroxide, calcium sulfoaluminate, and aluminosilicate powders before adding them to the cementing system. Its core lies in pre-constructing a composite micro / nano active slurry by pre-calcining an halloysite-alum co-calcined composite with an active calcium component through an alkaline wet milling process. This creates a slurry containing active aluminum sulfoaluminate components, active aluminum silicate components, a fibrous or tubular halloysite framework, submicron-sized particles, and ettringite crystal nuclei. When this activated slurry is introduced into the cementing system, it not only significantly increases the early hydration rate but also effectively improves the spatial distribution of hydration products on the surface and within the pores of the halloysite framework. This allows ettringite and hydrated calcium aluminosilicate gels to adhere to and intertwine, forming a denser network structure of hydration products. This results in a simultaneous improvement in the early mechanical properties and later strength development of the cementing material. Attached Figure Description

[0027] Figure 1 The image shows a scanning electron microscope (SEM) image of the co-calcined alum-haloysite composite obtained by co-calcining halloysite and alum.

[0028] Figure 2 This is a scanning electron microscope (SEM) image of uncalcined halloysite.

[0029] Figure 3 This is a scanning electron microscope (SEM) image of halloysite after calcination. Detailed Implementation

[0030] 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. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0031] In the following examples and comparative examples, SS represents steel slag, S represents blast furnace slag, DG represents desulfurized gypsum, PAC represents polyaluminum chloride, CAH represents co-calcined alum-haloite composite, CSA represents calcium sulfoaluminate or calcium sulfoaluminate phase in sulfoaluminate cement, C represents silicate cement clinker, CH represents calcium hydroxide, and ACS represents composite micro-nano active slurry obtained by wet milling of CAH, CSA and CH.

[0032] Unless otherwise specified, the dosage of SS, S, and DG is a percentage of the mass of the cementitious components; the dosage of PAC, CAH, CSA, and CH is based on the total mass of the basic cementitious components composed of SS, S, and DG.

[0033] The preparation method of CAH is as follows: Alum and halloysite are mixed at a mass ratio of 1:1.5, placed in a muffle furnace and heated to 750°C at 5°C / min, kept at the temperature for 2 hours, and then cooled to obtain CAH.

[0034] The preparation method of the ACS is as follows: CAH, CSA and CH are weighed and added to water at a water-to-solid mass ratio of 1.0:1. The mixture is wet-milled for 45 min to obtain ACS with a D50 of approximately 450 nm, an average particle size of approximately 0.65 μm, and a D90 not greater than 2 μm. This slurry is added to the gelling system as a whole without solid-liquid separation, and its water content is included in the total mixing water.

[0035] Example 1: This example provides a composite micro-nano active slurry activated solid waste-based cementitious material, whose cementitious components consist of 30% SS, 55% S and 15% DG, and are externally doped with 0.5% PAC and ACS; wherein ACS includes 1.0% CAH, 3% CSA and 1.0% CH by mass of the total cementitious components.

[0036] The cementitious material is prepared by the following method: SS, S and DG are mixed in proportion, PAC and ACS slurry are added, mixing water is added, and the mixture is stirred, molded, and cured under standard curing conditions to the specified age.

[0037] Example 2 is basically the same as Example 1, except that: ACS includes 1.5% CAH, 3% CSA and 1.0% CH by total mass of gelling components.

[0038] Example 3 is basically the same as Example 1, except that: ACS includes 2.0% CAH, 3% CSA and 1.0% CH by total mass of gelling components.

[0039] Example 4 is basically the same as Example 2, except that the PAC doping amount is 0.4%, the CSA doping amount is 2%, and the CH doping amount is 0.8%.

[0040] Example 5 is basically the same as Example 2, except that the mass ratio of SS, S and DG is 28:57:15, that is, the gelling component is composed of 28% SS, 7% S and 15% DG.

[0041] Comparative Example 1: This comparative example is a blank group. The gelling components consist of 30% SS, 55% S and 15% DG, without any external admixtures PAC, ACS (CAH, CSA and CH).

[0042] Comparative Example 2: The gelling component of this comparative example consists of 29% SS, 55% S, and 15% DG, with CSA added to replace SS, i.e., 1% CSA was added directly to the gelling component in the form of dry powder.

[0043] Comparative Example 3: The gelling component of this comparative example consists of 27% SS, 55% S, and 15% DG, with CSA added to replace SS, i.e., 3% CSA was added and directly added to the gelling component in the form of dry powder.

[0044] Comparative Example 4: The gelling components of this comparative example consist of 25% SS, 55% S, and 15% DG, with CSA added to replace SS, i.e., 5% CSA was added.

[0045] Comparative Example 5: The gelling components of this comparative example consist of 29% SS, 55% S, and 15% DG, with C replacing SS, i.e., 1% C was added.

[0046] Comparative Example 6: The gelling components of this comparative example consist of 27% SS, 55% S, and 15% DG, with C replacing SS, i.e., 3% C was added.

[0047] Comparative Example 7: The gelling components of this comparative example consist of 25% SS, 55% S, and 15% DG, with C added to replace SS, i.e., 5% C was added.

[0048] Comparative Example 8: The gelling components of this comparative example consist of 30% SS, 55% S, and 15% DG, with 0.2% PAC added externally, and no ACS added.

[0049] Comparative Example 9: The gelling components of this comparative example consist of 30% SS, 55% S, and 15% DG, with 0.5% PAC added externally, and no ACS added.

[0050] Comparative Example 10: The gelling components of this comparative example consist of 30% SS, 55% S, and 15% DG, with 1.0% PAC added externally, and no ACS added.

[0051] Comparative Example 11: The gelling components of this comparative example consist of 30% SS, 55% S, and 15% DG, with external admixtures of 0.5% PAC, 1.5% CAH, 3% CSA, and 1.0% CH added directly to the gelling components in dry powder form without co-wet milling.

[0052] The raw material ratios and addition methods for the examples and comparative examples are shown in Table 1 below.

[0053] Table 1

[0054] The flexural strength, compressive strength, and setting time of the examples and comparative examples were tested, and the results are shown in Tables 2 and 3 below.

[0055] Table 2

[0056] Table 3

[0057] As shown in Table 2, the 3-day and 28-day compressive strengths of the blank group (Comparative Example 1) were 14.6 MPa and 25.2 MPa, respectively, indicating that the basic activity of the steel slag-slag-desulfurized gypsum ternary system was low. The addition of CSA (Comparative Examples 2 to 4) or C (Comparative Examples 5 to 7) alone improved the strength to some extent, but the early strength remained low or required a reduction in the steel slag content. The addition of PAC (Comparative Examples 9 and 10) alone at a dosage of 0.5% achieved a 28-day compressive strength of 46.1 MPa, but the 3-day compressive strength was only 17.6 MPa, indicating limited early strengthening effect; the strength decreased at all ages when the dosage increased to 1.0%. Adding CAH, CSA, and CH in dry powder form to PAC at 0.5% (Comparative Example 11) increased the 3-day and 28-day compressive strengths to 21.2 MPa and 48.5 MPa, respectively. In Examples 1 to 5, CAH, CSA, and CH were co-wet-milled and then added as a whole in the form of ACS slurry. The 3-day and 28-day compressive strengths of each example were higher than those of the corresponding dry powder addition groups. Among them, the 3-day and 28-day compressive strengths of Example 2 reached 23.2 MPa and 52.4 MPa, respectively, which were significantly better than those of the comparative examples. The above results show that the present invention constructs a composite micro-nano active slurry by co-wet milling, which allows each activating component to fully exert its synergistic effect and achieves simultaneous improvement in the early and late strength of solid waste-based cementitious materials.

[0058] As shown in Table 3, the initial setting time of the blank group (Comparative Example 1) was 580 min, and the final setting time was 880 min, which was relatively long. The initial and final setting times of the PAC 0.5% single-admixture group (Comparative Example 9) were 610 min and 895 min, respectively, which were longer than those of the blank group, indicating that the addition of PAC alone had a certain delaying effect on setting. After adding CAH, CSA, and CH in dry powder form to the PAC 0.5% group (Comparative Example 11), the initial and final setting times were shortened to 390 min and 640 min, respectively, and the setting was significantly accelerated. In Example 2, CAH, CSA, and CH were wet-milled together and then added as a whole in the form of ACS slurry, which further shortened the initial and final setting times to 350 min and 610 min, respectively, which were shortened by about 40 min and 30 min, respectively, compared with the dry powder addition group. The above results show that by pre-wetting to form a composite micro-nano active slurry, the present invention enables the uniform dispersion of ettringite crystal nuclei during the wet grinding stage, effectively avoiding the risk of uncontrolled coagulation caused by localized concentrated hydration of calcium sulfoaluminate in the main cementitious system, and achieving reasonable control of coagulation time.

[0059] Electron microscopy was performed on uncalcined halloysite, halloysite calcined alone, and the co-calcined alum-haloysite composite obtained by co-calcining halloysite with alum.

[0060] Figure 2 This is a scanning electron microscope (SEM) image of uncalcined halloysite. Figure 2 As can be seen, uncalcined halloysite has a loose fibrous or tubular morphology, with a smooth fiber surface and few active sites.

[0061] Figure 3 This is a scanning electron microscope (SEM) image of halloysite after calcination. Figure 3 It is evident that after calcination, the fiber morphology of halloysite exhibits a certain degree of collapse and adhesion, while the surface remains relatively smooth and the active groups are not sufficiently exposed.

[0062] Figure 1 This is a scanning electron microscope (SEM) image of the co-calcined alum-haloysite composite obtained by co-calcining halloysite and alum. Figure 1 It is evident that after co-calcination with alum, the fibrous framework of halloysite is well preserved, exhibiting a dense and intact structure. Simultaneously, active clusters formed by the decomposition of alum are uniformly distributed on the fiber surface. These two elements are interlocked, forming a micro-nano composite structure with a fibrous framework as support and highly dispersed active substances. Compared to uncalcined halloysite, the surface roughness of the co-calcined composite is significantly increased, providing numerous active attachment sites for the nucleation and growth of hydration products. Compared to halloysite calcined alone, the co-calcined composite maintains a more complete fiber morphology and a more uniform distribution of active particles. This indicates that the introduction of alum effectively inhibits structural collapse during the high-temperature calcination process of halloysite, while achieving synergistic activation and modification of halloysite through surface etching and loading of active components.

[0063] Based on the above results, this invention addresses the problems of slow reaction rate and low early strength in the steel slag-slag-gypsum ternary system by co-calcining an alum-haloite composite, calcium sulfoaluminate, and calcium hydroxide together with water to form a composite micro-nano active slurry, which is then synergistically added to the cementing system with polyaluminum chloride. The overall addition of this slurry enables the rapid formation and densification of ettringite and C-(A)-SH gel, improving both the early and later strength of the material.

[0064] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention used to illustrate the technical solutions of the present invention, and are not intended to limit the invention, nor are they intended to limit the patent scope of the present invention. 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 or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. That is to say, any changes or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but whose technical problems are still consistent with the present invention, should be included within the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention to other related technical fields are similarly included within the patent protection scope of the present invention.

Claims

1. A composite micro-nano activated slurry for activating solid waste-based cementitious materials, characterized in that, It includes the following gel components by mass percentage: 20-35% steel slag, 45-65% blast furnace slag, 8-20% desulfurized gypsum; and externally added polyaluminum chloride and composite micro-nano active slurry; The dosage of polyaluminum chloride is 0.2-0.8% of the total mass of the gelling components, and the dosage of composite micro-nano active slurry is 2.3-9% of the total mass of the gelling components. The composite micro-nano active slurry is obtained by wet milling co-calcined alum-haloite composite, calcium sulfoaluminate and calcium hydroxide in an aqueous medium. The composite micro-nano active slurry is added to the gelling components as a whole without solid-liquid separation.

2. The cementitious material according to claim 1, characterized in that, The co-calcined alum-haloyite composite was obtained by mixing alum and halloyite at a mass ratio of 1:0.5-3 and then co-calcining them at 650-800℃ for 0.5-3 hours.

3. The cementitious material according to claim 2, characterized in that, The mass ratio of alum to halloysite is 1:1-2, and the calcination temperature is 700-760℃; the halloysite is fibrous or tubular halloysite.

4. The cementitious material according to claim 1, characterized in that, The co-calcined alum-haloite composite, calcium sulfoaluminate, calcium hydroxide and water were mixed and wet-milled for 10-90 min to obtain a composite micro-nano active slurry. The water-to-solid mass ratio during wet grinding is 0.4-2.0:1, the mass ratio of grinding balls to solid materials is 5:1-20:1, the grinding speed is 200-600 r / min, and the D50 of the solid particles in the slurry after wet grinding is 300-800 nm, the average particle size is 0.5-1.0 μm, and the D90 is not greater than 2 μm.

5. The cementitious material according to claim 1, characterized in that, The amount of co-calcined alum-halothite composite is 0.8-2.5% of the total mass of the cementing components, the amount of calcium sulfoaluminate is 1-5% of the total mass of the cementing components, and the amount of calcium hydroxide is 0.5-1.5% of the total mass of the cementing components.

6. The cementitious material according to claim 5, characterized in that, In the composite micro-nano active slurry, the amount of calcined alum-haloite composite is 1.2-2.2% of the total mass of the cementitious components, the amount of calcium sulfoaluminate is 2-4% of the total mass of the cementitious components, and the amount of calcium hydroxide is 0.6-1.2% of the total mass of the cementitious components.

7. The cementitious material according to claim 5, characterized in that, In the composite micro-nano active slurry, the amount of calcined alum-haloite composite is 1.5% of the total mass of the cementitious components, the amount of calcium sulfoaluminate is 3% of the total mass of the cementitious components, and the amount of calcium hydroxide is 1.0% of the total mass of the cementitious components.

8. The cementitious material according to claim 1, characterized in that, The mass ratio of steel slag, blast furnace slag and desulfurized gypsum is 25-32:52-60:10-18; the dosage of polyaluminum chloride is 0.3-0.6% of the total mass of the cementitious components.

9. The cementitious material according to claim 8, characterized in that, The mass ratio of steel slag, blast furnace slag, and desulfurized gypsum is 30:55:15; the dosage of polyaluminum chloride is 0.5% of the total mass of the cementitious components.

10. The method for preparing composite micro-nano activated slurry-based solid waste cementitious material according to any one of claims 1-9, characterized in that, Includes the following steps: The co-calcined alum-haloite composite, calcium sulfoaluminate and calcium hydroxide were wet-milled together in water to obtain a composite micro-nano active slurry. The amount of water used in the wet milling was included in the total mixing water of the cementitious material. Steel slag, desulfurized gypsum and slag are mixed to obtain a cementitious component; The obtained composite micro-nano active slurry was added to the obtained gelling component without solid-liquid separation, and mixing water was added to the required total mixing water volume. The mixture was stirred evenly to obtain solid waste-based gelling material. The total mixing water volume is determined according to GB / T 17671 standard or target performance.

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