A pre-mineralized carbide slag-slag composite material curing agent for constructing a high-efficiency hydration reaction system and application thereof

Abstract

The present application relates to a kind of pre-mineralization carbide slag-slag composite material curing agent for building efficient hydration reaction system and its application, the present application is first to the mixture of slag-carbide slag pre-mineralization modification, remodeling interface activity, and compound desulfurization gypsum, successfully build alkali-sulfate-mineralization multiple excitation system.Not only significantly improve the early and middle and late reaction activity of whole solid waste curing agent, effectively improve the unconfined compressive strength of solidified engineering slag, water stability, wet and dry cycle resistance and shrinkage resistance, more in realizing carbon dioxide efficient storage, realize the deep resource utilization of slag, carbide slag and desulfurization gypsum in engineering slag stabilization.

Description

Technical Field

[0001] This invention relates to a pre-mineralized carbide slag-slag composite material curing agent for constructing an efficient hydration reaction system and its application, belonging to the field of slag and soil improvement technology. Background Technology

[0003] Traditional slag stabilization technologies primarily use ordinary silicate cement as a solidifying agent. However, cement production is a typical high-energy-consuming and high-emission process, emitting approximately 0.8 to 1 ton of carbon dioxide per ton of cement produced. Furthermore, for waste slag with high moisture content and high clay content, using cement alone often suffers from limitations such as slow strength gain and susceptibility to shrinkage cracking. Utilizing industrial solid waste (such as slag, carbide slag, and desulfurized gypsum) for synergistic activation, combined with carbon dioxide mineralization technology, to prepare low-carbon solidification materials demonstrates enormous engineering application potential and significant environmental benefits.

[0004] However, existing composite solidification systems based on industrial solid waste still face serious limitations in reactivity during practical applications. On the one hand, the potential hydration activity of solid wastes such as slag is released slowly, often requiring a significant increase in the dosage of alkali activator to ensure strength. This not only increases material costs but may also lead to excessively high alkalinity in the leachate of the solidified soil, disrupting the surrounding ecological balance. On the other hand, while carbon dioxide mineralization technology can play a role in carbon sequestration and physical filling, under current technological conditions, the mineralization process often competes with the hydration reaction: excessive mineralization consumes calcium hydroxide in the system, causing the pH value to drop below the threshold for slag glass dissociation, resulting in severe interfacial passivation. This passivation causes the surface of slag particles to be coated with a dense calcium carbonate shell, cutting off the ion migration pathways required for the formation of subsequent hydration products. This limits the solidification effect of the solid waste solidifier, making it difficult to meet the performance requirements of high-grade roads and infrastructure projects.

[0005] Therefore, breaking down the kinetic barrier between mineralization and activation, and effectively enhancing the hydration reaction activity of the entire solid waste system, is a key scientific issue for realizing the large-scale and high-value application of industrial solid waste in the solidification of excavated soil in engineering projects. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a pre-mineralized carbide slag-slag composite material curing agent for constructing an efficient hydration reaction system and its application.

[0007] This invention first pre-mineralizes a mixture of slag and carbide slag, modifies and reshapes the interfacial activity, constructs an efficient hydration reaction system, and develops a novel green solidifying agent that can both comprehensively utilize industrial waste and seal carbon dioxide on a large scale, and significantly improve the mechanical properties and environmental stability of engineering slag soil. It has important scientific significance and engineering application value.

[0008] The present invention is achieved through the following technical solution.

[0009] In a first aspect, the present invention provides a pre-mineralized carbide slag-slag composite material curing agent for constructing an efficient hydration reaction system.

[0010] The curing agent is composed of the following raw materials in the following mass percentages:

[0011] Premineralized composite materials 70-90%, desulfurized gypsum 10-30%;

[0012] The pre-mineralized composite material is obtained by carbon dioxide mineralization modification of a mixture of slag and carbide slag. Before modification, the mass ratio of slag to carbide slag is (35~63):(7~35).

[0013] According to a preferred embodiment of the present invention, the pre-mineralized composite material is obtained by the following preparation method:

[0014] (1) Mix slag and carbide slag to obtain a mixture. Disperse the mixture in deionized water under stirring conditions to obtain a uniform solid-liquid slurry system. Use a pH monitoring system to obtain the pH change of the system in real time.

[0015] (2) After the system is in ionization equilibrium and the pH value is stable, gaseous CO2 is introduced into the slurry to carry out the mineralization reaction. When the pH value drops to 7.5±0.2, it is the mineralization termination threshold. Stop the gas supply and maintain the stirring state until the pH value is constant to ensure that the gas-solid-liquid three-phase reaction is sufficient and obtain the carbonation composite slurry.

[0016] (3) The carbonated composite slurry is subjected to solid-liquid separation, collected, filtered, dried and crushed to obtain a pre-mineralized composite material.

[0017] According to a preferred embodiment of the present invention, in step (1), the slag dry material is S95 grade granulated blast furnace slag powder, the Ca(OH)2 content in the carbide slag dry material is ≥85%, and the particle size range of the slag dry material and carbide slag dry material is 0.0001mm~1mm.

[0018] According to the present invention, in step (1), the mass ratio of the slag to the carbide slag is (35~63):(7~35).

[0019] According to the present invention, in step (1), the dispersion in deionized water is carried out in a constant temperature water bath, and the water bath temperature is 20°C to 80°C, more preferably 20°C.

[0020] According to the present invention, in step (1), the mass ratio of deionized water to mixture is (2~10):1, and more preferably, the mass ratio of deionized water to mixture is (4~8):1.

[0021] According to the present invention, in step (1), the stirring speed is 300-800 r / min and the stirring time is 5-60 min.

[0022] According to the present invention, in step (2), the mineralization reaction uses CO2 gas with a volume fraction of 15%-100%, and more preferably, the mineralization reaction uses CO2 gas with a volume fraction of 100%.

[0023] According to the present invention, in step (2), the CO2 gas flow rate is controlled at 0.1-1.0 L / min, more preferably 0.4 L / min.

[0024] According to the present invention, in step (2), after stopping the aeration, the stirring time is continued for 10-30 minutes.

[0025] According to the present invention, in step (3), the drying conditions are drying to constant weight at 60-105°C, and more preferably, the drying conditions are drying at 105°C.

[0026] A preferred embodiment of the present invention is a pre-mineralized carbide slag-slag composite material curing agent for constructing an efficient hydration reaction system.

[0027] The curing agent is composed of the following raw materials in the following mass percentages:

[0028] Premineralized composite material 70%, desulfurized gypsum 30%;

[0029] In a second aspect, the present invention provides the application of the above-mentioned premineralized carbide slag-slag composite material curing agent.

[0030] The above-mentioned premineralized carbide slag-slag composite material curing agent is used to stabilize or solidify excavated slag in engineering projects.

[0031] According to a preferred embodiment of the present invention, the specific application method is as follows:

[0032] 1) The engineering waste soil to be treated is mechanically ground or crushed to a particle size ≤5mm and dried to constant weight to eliminate the interference of free water, thus obtaining pretreated waste soil;

[0033] 2) Add water to the pretreated slag and stir, then place it in a sealed environment for impregnation treatment to obtain uniform wet engineering slag;

[0034] 3) Add the above-mentioned premineralized carbide slag-slag composite material curing agent to the wet engineering waste soil, and stir until the curing agent and the waste soil particles are fully and evenly mixed to complete the stabilization or solidification treatment of the engineering waste soil.

[0035] According to a preferred embodiment of the present invention, in step 1), mechanical grinding or pulverization is performed until the particle size is ≤2 mm.

[0036] According to a preferred embodiment of the present invention, in step 1), drying is performed by placing the product in a constant temperature oven at 105℃±5℃ for 12 hours until constant weight is achieved.

[0037] According to a preferred embodiment of the present invention, in step 2), the mass ratio of pretreated slag to water is (3-5):1, and more preferably 4:1.

[0038] According to a preferred embodiment of the present invention, in step 2), the stirring time for adding water is 180~240s.

[0039] According to a preferred embodiment of the present invention, in step 2), the sealing and impregnation time is 12-24 hours, and more preferably 12 hours.

[0040] According to a preferred embodiment of the present invention, in step 3), the amount of premineralized carbide slag-slag composite material curing agent added is 8%-15% of the mass of the pretreated slag, and more preferably 10%.

[0041] According to a preferred embodiment of the present invention, in step 3), the stirring time is 180-300 s.

[0042] According to a preferred embodiment of the present invention, the stabilized engineering waste soil is placed in a standard curing chamber at a temperature of 20±2℃ and a relative humidity of ≥95%. The stabilized engineering waste soil is subjected to unconfined compressive strength tests, bearing capacity tests, water stability coefficient ratio tests, wet-dry cycle tests, and drying shrinkage tests in accordance with the standards of "Soil Stabilizing Admixtures" (CJT486-2015), "Highway Geotechnical Test Procedures" (JTG3430-2020), "Highway Engineering Inorganic Binder Stabilized Materials Test Procedures" (JTG 3441-2024), and "Standard Test Method for Wetting and Drying Test of Solid Wastes" (ASTM D4843-88).

[0043] The present invention also provides a method for evaluating the reactivity of the curing agent of the above-mentioned premineralized carbide slag-slag composite material.

[0044] The evaluation method for the reactivity of the premineralized carbide slag-slag composite material curing agent adopts the activity index and heat of hydration as the core evaluation indicators.

[0045] The steps for the activity index test are as follows:

[0046] a. Mix the above-mentioned premineralized carbide slag-slag composite material curing agent with P .O42.5 grade silicate cement is mixed at a 1:1 mass ratio to obtain a composite cementitious material. The composite cementitious material is then mixed with water at a water-to-cement mass ratio (water-cement ratio) of 0.5 to form a homogeneous slurry. 100% P... . O42.5 grade silicate cement was mixed with water in the same proportion to make pure cement paste as a control;

[0047] b. Inject the two groups of slurry into molds to make cubic specimens, with 3 parallel specimens for each group;

[0048] c. After molding, the specimens are cured in the mold for 24 hours. After demolding, they are transferred to a curing chamber for curing. The curing temperature is 20±1℃ and the relative humidity is ≥95%. The curing period is 28 days.

[0049] d. After reaching the curing age, the compressive strength of each group of specimens was measured; the ratio of the 28-day compressive strength of each group of specimens to the 28-day compressive strength of cement paste was used as the activity index.

[0050] The steps for testing the heat of hydration are as follows:

[0051] The exothermic behavior of the premineralized carbide slag-slag composite material curing agent during the hydration process was monitored using the isothermal microcalorimetry method. The mass ratio of water to composite material curing agent was 0.5, and the mass of dry powder of composite material curing agent was 10 mg.

[0052] The technical features and advantages of this invention are as follows:

[0053] 1. This invention first pre-mineralizes and modifies a mixture of slag and carbide slag to reshape its interfacial activity, and then combines it with desulfurized gypsum to successfully construct an alkali-sulfate-mineralization multi-activation system. This not only significantly improves the early and mid-to-late-stage reactivity of the solid waste solidifying agent, effectively enhancing the unconfined compressive strength, water stability, resistance to wet-dry cycles, and resistance to drying shrinkage of solidified engineering waste soil, but also achieves deep resource utilization of slag, carbide slag, and desulfurized gypsum in the stabilization of engineering waste soil while simultaneously realizing efficient carbon dioxide sequestration.

[0054] 2. This invention first pre-mineralizes a mixture of slag and carbide slag, achieving in-situ modification and activation of the slag particle surface. The invention utilizes the strongly alkaline environment generated by the dissolution of carbide slag to induce premature dissociation of the slag surface. During the mineralization stage, gaseous CO2 and calcium components in the carbide slag undergo heterogeneous nucleation on the slag particle surface, resulting in the in-situ growth of micro / nano-sized calcium carbonate crystal nuclei with high adsorption energy. This process effectively removes the acidic film from the slag surface and forms a large amount of highly active pozzolanic silica gel. This micro-interface reshaping of the crystal nucleus + gel avoids the dense encapsulation of active sites by the carbonized shell in traditional processes, fundamentally improving the reaction kinetics of the composite system.

[0055] 3. The stabilizing effect of the solidifying agent of this invention on engineering waste soil stems from the combined effect of core-shell induction and the synergistic interplay of multiphase products. The strength development of the solidified system is the result of the co-evolution of mineralization products, mineralization processes, and sulfate-inducing products. The micro-nano CaCO3 generated by pre-mineralization serves as a highly efficient nucleation site, significantly reducing the crystallization pressure of subsequent hydration products and inducing rapid transformation of calcium, silicon, and aluminum components in the system. The residual alkaline environment provided by the carbide slag and the sufficient SO4 provided by the desulfurized gypsum further enhance the stabilizing effect. 2- Through synergistic action, reactive aluminates rapidly react to generate a large number of acicular ettringite crystals. These crystals interweave within the pores of the soil particles, constructing a dense, fibrous three-dimensional network framework that provides early strength. As the reaction progresses, highly reactive silica gel and calcium ions continuously condense to form amorphous CSH gel. This gel, like glue, encapsulates and fills the pores between the ettringite framework and the soil clay particles, achieving overall densification of the soil structure through extremely strong interfacial adhesion, endowing the solidified body with excellent long-term mechanical properties and resistance to environmental erosion. Attached Figure Description

[0056] To make the technical solutions and working principles of the embodiments of the present invention clearer, the specific implementation methods of the present invention will be briefly described below with reference to the accompanying drawings. It should be understood that the drawings described herein are only for illustrating and explaining typical embodiments of the present invention and do not constitute a substantial limitation on the scope of protection of the present invention.

[0057] Figure 1 The image shows a scanning electron microscope image of the solidified construction waste soil in Example 2 at 5000x magnification.

[0058] Figure 2 The image shows a scanning electron microscope image of the solidified engineering waste soil in Example 3 at 5000x magnification.

[0059] Figure 3 The image shows a scanning electron microscope image of the solidified engineering waste soil in Example 5 at 5000x magnification.

[0060] Figure 4 The image shows a scanning electron microscope image of the solidified construction waste soil in Comparative Example 1 at 5000x magnification.

[0061] Figure 5 The results show the activity index of different pre-mineralized composite curing agents;

[0062] Figure 6 The cumulative hydration exothermic results are for different pre-mineralized composite material curing agents;

[0063] Figure 7 The results show the unconfined compressive strength of the solidified engineering waste soil in different embodiments;

[0064] Figure 8The bearing capacity ratio results of solidified engineering waste soil in different embodiments;

[0065] Figure 9 The results show the water stability coefficients of the solidified engineering waste soil in different embodiments;

[0066] Figure 10 Results of wet-dry cycle performance of solidified engineering waste soil in different embodiments;

[0067] Figure 11 The results show the drying shrinkage properties of stabilized engineering waste soil in different embodiments. Detailed Implementation

[0068] Example 1

[0069] A pre-mineralized carbide slag-slag composite material curing agent, wherein the curing agent is composed of the following components in weight percentage:

[0070] Pre-mineralized composite material 70%, desulfurized gypsum 30%

[0071] The preparation steps of the pre-mineralized composite material are as follows:

[0072] (1) Mix the slag and carbide slag in a mass ratio of 1:1 to obtain a mixture. Add the mixture to deionized water and stir and disperse at 300 rpm for 40 min at a constant temperature of 20℃. Use a pH meter to monitor the alkalinity evolution of the slurry in real time. The mass ratio of deionized water to the mixture is 6:1.

[0073] (2) After the pH value stabilizes, CO2 gas is introduced. The CO2 gas flow rate is controlled at 0.4 L / min. When the pH value drops to 7.4, the CO2 is introduced and stirring is continued for 30 min until the pH value stabilizes. This ensures that the mineralization reaction is complete and pre-mineralized composite slurry is obtained.

[0074] (3) The premineralized composite slurry was subjected to solid-liquid separation, collected, filtered, and dried at 105℃ to constant weight to obtain the premineralized composite material.

[0075] The application method of the curing agent for premineralized carbide slag-slag composite materials is as follows:

[0076] 1) The engineering waste soil to be treated is mechanically crushed to a particle size ≤2mm, and then placed in a constant temperature oven at 105℃ for 12 hours to constant weight to obtain pretreated waste soil;

[0077] 2) Add water to the pretreated slag and stir for 180 seconds. The mass ratio of pretreated slag to water is 4:1. After stirring, place the material in a sealed environment for 12 hours to obtain uniform wet engineering slag.

[0078] 3) Add the above-mentioned premineralized carbide slag-slag composite material curing agent to the wet engineering waste soil, stir for 180s until the curing agent and the waste soil particles are fully mixed and uniform, and complete the stabilization or curing treatment of the engineering waste soil. The amount of curing agent is 10% of the mass of the pretreated waste soil.

[0079] Example 2

[0080] A pre-mineralized carbide slag-slag composite material curing agent, wherein the curing agent is composed of the following components in weight percentage:

[0081] Pre-mineralized composite material 70%, desulfurized gypsum 30%

[0082] The premineralized composite material was prepared according to Example 1, except that slag and carbide slag were mixed in a mass ratio of 3:1.

[0083] The application method of the curing agent for premineralized carbide slag-slag composite materials is as follows:

[0084] 1) The engineering waste soil to be treated is mechanically crushed to a particle size ≤2mm, and then placed in a constant temperature oven at 105℃ for 12 hours to constant weight to obtain pretreated waste soil;

[0085] 2) Add water to the pretreated slag and stir for 180 seconds. The mass ratio of pretreated slag to water is 4:1. After stirring, place the material in a sealed environment for 12 hours to obtain uniform wet engineering slag.

[0086] 3) Add the above-mentioned pre-mineralized carbide slag-slag composite material curing agent to the wet engineering waste soil, and stir for 180 seconds until the curing agent and soil particles are fully and evenly mixed to complete the stabilization or solidification treatment of the engineering waste soil. The amount of curing agent used is 10% of the mass of the pre-treated waste soil. The solidified engineering waste soil is observed under a scanning electron microscope at 5000x magnification. Figure 1 ,pass Figure 1 An extremely dense and continuous microstructure was observed. The sample contained a large number of regularly shaped, sharply defined cubic or rhombohedral crystals, which are calcite precipitates generated by the carbonation reaction. These calcium carbonate crystals are uniform in size and densely distributed, effectively filling the pores within the solidified soil. More importantly, almost no obvious pores or cracks were visible between the crystals, indicating that the large number of calcium carbonate crystals produced by synergistic carbonation not only acted as physical fillers as micro-aggregates but also intertwined tightly with the CSH gel generated in the system, forming a highly integrated hardened framework structure.

[0087] Example 3

[0088] A pre-mineralized carbide slag-slag composite material curing agent, wherein the curing agent is composed of the following components in weight percentage:

[0089] Pre-mineralized composite material 70%, desulfurized gypsum 30%

[0090] The premineralized composite material was prepared according to Example 1, except that slag and carbide slag were mixed in a mass ratio of 5:1.

[0091] The application method of the curing agent for premineralized carbide slag-slag composite materials is as follows:

[0092] 1) The engineering waste soil to be treated is mechanically crushed to a particle size ≤2mm, and then placed in a constant temperature oven at 105℃ for 12 hours to constant weight to obtain pretreated waste soil;

[0093] 2) Add water to the pretreated slag and stir for 180 seconds. The mass ratio of pretreated slag to water is 4:1. After stirring, place the material in a sealed environment for 12 hours to obtain uniform wet engineering slag.

[0094] 3) Add the above-mentioned pre-mineralized carbide slag-slag composite material curing agent to the wet engineering waste soil, and stir for 180 seconds until the curing agent and soil particles are fully and evenly mixed to complete the stabilization or solidification treatment of the engineering waste soil. The amount of curing agent used is 10% of the mass of the pre-treated waste soil. The solidified engineering waste soil is observed under a scanning electron microscope at 5000x magnification. Figure 2 Although the number of calcium carbonate crystals is relatively small compared to Figure 1 It's slightly less, but it still maintains a good structural integrity.

[0095] Example 4

[0096] A pre-mineralized carbide slag-slag composite material curing agent, wherein the curing agent is composed of the following components in weight percentage:

[0097] Pre-mineralized composite material 70%, desulfurized gypsum 30%

[0098] The premineralized composite material was prepared according to Example 1, except that slag and carbide slag were mixed in a mass ratio of 7:1.

[0099] The application method of the curing agent for premineralized carbide slag-slag composite materials is as follows:

[0100] 1) The engineering waste soil to be treated is mechanically crushed to a particle size ≤2mm, and then placed in a constant temperature oven at 105℃ for 12 hours to constant weight to obtain pretreated waste soil;

[0101] 2) Add water to the pretreated slag and stir for 180 seconds. The mass ratio of pretreated slag to water is 4:1. After stirring, place the material in a sealed environment for 12 hours to obtain uniform wet engineering slag.

[0102] 3) Add the above-mentioned premineralized carbide slag-slag composite material curing agent to the wet engineering waste soil, stir for 180s until the curing agent and the waste soil particles are fully mixed and uniform, and complete the stabilization or curing treatment of the engineering waste soil. The amount of curing agent is 10% of the mass of the pretreated waste soil.

[0103] Example 5

[0104] A pre-mineralized carbide slag-slag composite material curing agent, wherein the curing agent is composed of the following components in weight percentage:

[0105] Pre-mineralized composite material 70%, desulfurized gypsum 30%

[0106] The premineralized composite material was prepared according to Example 1, except that slag and carbide slag were mixed in a mass ratio of 9:1.

[0107] The application method of the curing agent for premineralized carbide slag-slag composite materials is as follows:

[0108] 1) The engineering waste soil to be treated is mechanically crushed to a particle size ≤2mm, and then placed in a constant temperature oven at 105℃ for 12 hours to constant weight to obtain pretreated waste soil;

[0109] 2) Add water to the pretreated slag and stir for 180 seconds. The mass ratio of pretreated slag to water is 4:1. After stirring, place the material in a sealed environment for 12 hours to obtain uniform wet engineering slag.

[0110] 3) Add the above-mentioned pre-mineralized carbide slag-slag composite material curing agent to the wet engineering waste soil, and stir for 180 seconds until the curing agent and soil particles are fully and evenly mixed to complete the stabilization or solidification treatment of the engineering waste soil. The amount of curing agent used is 10% of the mass of the pre-treated waste soil. The solidified engineering waste soil is observed under a scanning electron microscope at 5000x magnification. Figure 3 ,pass Figure 3 It can be seen that although the number of clear and regular calcite crystals has decreased, there are no large gaps and pores between the grains, and the structure is relatively dense.

[0111] Comparative Example 1

[0112] A slag-carbide slag-desulfurized gypsum curing agent, wherein the curing agent is composed of the following components in weight percentage:

[0113] Slag 63%, calcium carbide slag 7%, desulfurized gypsum 30%.

[0114] The application method of slag-carbide slag-desulfurized gypsum curing agent is as follows:

[0115] 1) The engineering waste soil to be treated is mechanically ground or crushed until the particle size is ≤2mm, and then placed in a constant temperature oven at 105℃±5℃ for 12h to constant weight to obtain pretreated waste soil.

[0116] 2) Add water to the pretreated slag and stir for 180 seconds. The mass ratio of pretreated slag to water is 4:1. After stirring, place the material in a sealed environment for 12 hours to obtain uniform wet engineering slag.

[0117] 3) Add slag-carbide slag-desulfurized gypsum solidifying agent to the wet construction waste soil, and stir for 180 seconds until the solidifying agent is fully and evenly mixed with the waste soil particles. This completes the stabilization or solidification treatment of the construction waste soil. The amount of solidifying agent used is 10% of the mass of the pretreated waste soil. The solidified construction waste soil is observed under a scanning electron microscope at 5000x magnification. Figure 4 ,pass Figure 4 As can be seen, the image shows a distinctly loose matrix with numerous gaps and pores (dark areas) between the particles, lacking a continuous cementing phase to tightly bind the particles together.

[0118] Performance testing

[0119] 1. Evaluation of the reactivity of the curing agent:

[0120] (1) Activity index

[0121] The curing agent was mixed with P·O 42.5 grade cement at a 50% mass substitution rate, and cubic specimens with a side length of 70.7 mm (3 parallel samples per group) were prepared at a water-cement ratio of 0.5. After standard curing for 28 days, their compressive strength was measured, and the percentage value of the strength of each group of specimens to the strength of the pure cement control group was calculated. This value was used as the activity index. The test results are shown in Table 1. Figure 5 .

[0122] Table 1. Test results of curing agent reactivity

[0123]

[0124] (2) Heat of hydration

[0125] The exothermic behavior of the pre-mineralized carbide slag-slag composite material and desulfurized gypsum curing agent during the hydration process was monitored using isothermal microcalorimetry. The water-cement ratio was 0.5, and the mass of the dry powder tested was 10 mg. The test results are shown in Table 2. Figure 6 .

[0126] Table 2 Test results of heat of hydration of curing agent

[0127]

[0128] From Table 1, Table 2, Figure 5 , Figure 6 The results show that, compared with the solidifier in Comparative Example 1, the soil solidifier in Example 5 exhibited a significant improvement in both the 28-day reactivity index and the 7-day cumulative heat release. The synergistic carbonation pretreatment of calcium carbide slag and blast furnace slag in the solidifier significantly enhanced its activity. This strongly demonstrates the promoting effect of pre-mineralization treatment on the reaction kinetics of the solidifier system. After pre-mineralization, the highly active silica gel generated in situ on the surfaces of the blast furnace slag and calcium carbide slag promoted the formation of more cementing products through the pozzolanic reaction, while the micro / nano-sized CaCO3 particles generated during the mineralization process exerted a nucleation-inducing effect, significantly reducing the nucleation potential energy of hydration products. The dramatic increase in heat release directly reflects the enhanced intensity of the hydration reaction within the system, indicating the formation of a more compact microstructure inside the solidified body.

[0129] In Examples 1-5, with further optimization of the curing agent components, the reactivity and exothermic reaction of the system showed a trend of first increasing and then decreasing. This is mainly due to the synergistic effect between the alkaline depolymerization of the carbide slag and the pre-mineralized products. The high concentration of OH- released from the dissolution of the carbide slag... - A strongly alkaline environment was established, which effectively induced further depolymerization of the glassy network in the slag during mineralization, accelerating the breaking of Si-O and Al-O bonds, thereby releasing more active silicon-aluminum monomers. The synergistic effect of CaCO3 crystal nucleation generated during mineralization, the strong alkalinity-accelerated depolymerization of the carbide slag, and the sulfate-induced activation of the desulfurized gypsum led to an increase in the reactivity of the curing agent.

[0130] 2. Tests for compressive strength, load-bearing ratio, water stability coefficient, resistance to wet-dry cycles, and shrinkage:

[0131] (1) The unconfined compressive strength of the solidified engineering slag was tested at 7 days, 14 days, 28 days and 56 days in accordance with the Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering (JTG 3441-2024);

[0132] (2) Conduct a bearing ratio test on the solidified engineering waste soil in accordance with the "Specifications for Geotechnical Testing of Highways" (JTG 3430-2020);

[0133] (3) Water stability tests were conducted on the solidified engineering waste soil for 7 days, 14 days, 28 days and 56 days in accordance with the "Soil Stabilizing Admixtures" (CJT 486-2015);

[0134] (4) Conduct wet-dry cycle tests on the solidified engineering waste soil according to the Standard Test Method for Wetting and Drying Test of Solid Wastes (ASTM D4843-88);

[0135] (5) Drying shrinkage tests were conducted on the solidified engineering slag at 1 day, 3 days, 7 days, 14 days, and 28 days in accordance with the "Test Procedure for Inorganic Binder Stabilized Materials in Highway Engineering" (JTG 3441-2024). The test results are shown in Table 3. The unconfined compressive strength, bearing ratio, water stability coefficient, wet-dry cycle properties, and drying shrinkage are shown in Table 3. Figure 7-11 .

[0136] Table 3. Test results of unconfined compressive strength, bearing ratio, water stability coefficient, wet-dry cycle properties, and drying shrinkage of different solidification engineering waste soils.

[0137]

[0138] Compared to Comparative Example 1, the solidified engineering waste soil in Example 5 exhibited improved 7-day, 14-day, 28-day, and 56-day unconfined compressive strength, bearing capacity ratio, 7-day water stability coefficient, 14-day water stability coefficient, 28-day water stability coefficient, and 56-day water stability coefficient. Furthermore, it showed reduced mass loss during wet-dry cycles, and decreased shrinkage strain at 1, 3, 7, 14, and 28 days. This indicates that the synergistic mineralization pretreatment of calcium carbide slag and blast furnace slag fundamentally improved the structural integrity of the solidified engineering waste soil under complex environments. This is mainly due to the rapid ionization of gaseous CO2 in the alkaline liquid phase created by the calcium carbide slag during the aqueous mineralization stage. This ionization induces selective dissolution of calcium and silicon components from the surface of solid particles, resulting in a reduction in particle size and effective removal of the acidic passivation layer on the surface. This process not only forms a large amount of silica gel components with high pozzolanic activity but also firmly attaches the in-situ generated micro-nano-sized calcium carbonate particles to the blast furnace slag surface. These particles serve as highly efficient nucleation sites, significantly reducing the nucleation energy barrier for subsequent hydration reactions.

[0139] Compared to Example 5, the unconfined compressive strength, bearing capacity ratio, and water stability coefficient of the solidified engineering waste soil in Examples 1-4 were all increased, while the mass loss and shrinkage strain during the wet-dry cycle were reduced. This is because the solidification effect of the solidifying agent in Examples 1-5 on the engineering waste soil is the result of the synergistic effect of mineralization, alkali-accelerated depolymerization, and sulfate activation. The pre-mineralization synergistic treatment of carbide slag and blast furnace slag transforms it into a pre-assembled active platform rich in metastable states. When compounded desulfurized gypsum is contacted with waste soil and water, a large amount of silica gel components with high pozzolanic activity react with the Ca in the desulfurized gypsum. 2+ Ions and SO4 2-Ionic reaction. Under the nucleation induction of the mineralized product nano-CaCO3, the system rapidly generates a large number of needle-like ettringite crystals. These crystals interweave within the pores of the slag particles, constructing a three-dimensional network framework in the early stages of strength development. With increasing age, the highly reactive silicon components in the mineralized powder continuously condense with calcium ions in the system, generating a large amount of amorphous CSH gel. This gel, as a matrix material, fills the interior of the ettringite framework and the pores between slag particles, achieving a significant refinement of the pore structure. This dense structure composed of "framework + filling" not only improves macroscopic mechanical strength but also significantly alleviates shrinkage caused by moisture migration through the micro-expansion compensation effect of ettringite, fundamentally improving the durability of solidified engineering slag.

Claims

1. A pre-mineralized carbide slag-slag composite material curing agent for constructing an efficient hydration reaction system, said curing agent being composed of the following raw materials in weight percentages: Premineralized composite materials 70-90%, desulfurized gypsum 10-30%; The pre-mineralized composite material is obtained by carbon dioxide mineralization modification of a mixture of slag and carbide slag. Before modification, the mass ratio of slag to carbide slag is (35~63):(7~35).

2. The pre-mineralized carbide slag-slag composite material curing agent according to claim 1, characterized in that, The pre-mineralized composite material is obtained by the following preparation method: (1) Mix slag and carbide slag to obtain a mixture. Disperse the mixture in deionized water under stirring conditions to obtain a uniform solid-liquid slurry system. Use a pH monitoring system to obtain the pH change of the system in real time. (2) After the system is in ionization equilibrium and the pH value is stable, gaseous CO2 is introduced into the slurry to carry out the mineralization reaction. When the pH value drops to 7.5±0.2, it is the mineralization termination threshold. Stop the gas supply and maintain the stirring state until the pH value is constant to ensure that the gas-solid-liquid three-phase reaction is sufficient and obtain the carbonation composite slurry. (3) The carbonated composite slurry is subjected to solid-liquid separation, collected, filtered, dried and crushed to obtain a pre-mineralized composite material.

3. The pre-mineralized carbide slag-slag composite material curing agent according to claim 2, characterized in that, In step (1), the slag dry material is S95 grade granulated blast furnace slag powder, the Ca(OH)2 content in the carbide slag dry material is ≥85%, and the particle size range of the slag dry material and carbide slag dry material is 0.0001mm~1mm. In step (1), the mass ratio of the slag to the carbide slag is (35~63):(7~35). The dispersion in deionized water is carried out in a constant temperature water bath, and the water bath temperature is 20℃~80℃.

4. The pre-mineralized carbide slag-slag composite material curing agent according to claim 2, characterized in that, In step (1), the mass ratio of deionized water to the mixture is (2~10):1, the stirring speed is 300-800 r / min, and the stirring time is 5-60 min.

5. The pre-mineralized carbide slag-slag composite material curing agent according to claim 2, characterized in that, In step (2), the mineralization reaction uses CO2 gas with a volume fraction of 15%-100%, and more preferably, the mineralization reaction uses CO2 gas with a volume fraction of 100%.

6. The pre-mineralized carbide slag-slag composite material curing agent according to claim 2, characterized in that, In step (2), the CO2 gas flow rate is controlled at 0.1-1.0 L / min, more preferably 0.4 L / min. After the gas flow is stopped, the stirring time is continued for 10-30 min. In step (3), the drying conditions are drying to constant weight at 60-105℃.

7. A pre-mineralized carbide slag-slag composite material curing agent for constructing an efficient hydration reaction system, said curing agent being composed of the following raw materials in weight percentages: The pre-mineralized composite material accounts for 70%, and the desulfurized gypsum accounts for 30%.

8. The application of the premineralized carbide slag-slag composite material curing agent according to claim 1, for stabilizing or curing excavated slag in engineering projects.

9. The application according to claim 8, characterized in that, The specific application methods are as follows: 1) The engineering waste soil to be treated is mechanically ground or crushed to a particle size ≤5mm and dried to constant weight to eliminate the interference of free water, thus obtaining pretreated waste soil; 2) Add water to the pretreated slag and stir, then place it in a sealed environment for impregnation treatment to obtain uniform wet engineering slag; 3) Add the above-mentioned premineralized carbide slag-slag composite material curing agent to the wet engineering waste soil, and stir until the curing agent and the waste soil particles are fully and evenly mixed to complete the stabilization or solidification treatment of the engineering waste soil.

10. The application according to claim 9, characterized in that, In step 1), the material is mechanically ground or pulverized to a particle size ≤2mm. In step 1), the material is dried in a constant temperature oven at 105℃±5℃ for 12 hours until constant weight. In step 2), the mass ratio of pretreated slag to water is (3-5):

1. In step 2), the water is added and stirred for 180~240s. In step 2), the sealing and impregnation time is 12~24h. In step 3), the amount of premineralized carbide slag-slag composite material curing agent added is 8%-15% of the mass of the pretreated slag.

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