An additive for solidifying slag and its preparation method

Abstract

This invention belongs to the field of roadbed solidification technology and relates to an additive for solidifying slag and its preparation method. Calculated by weight, it includes the following components: 15-25 parts mineral admixture, 5-10 parts modified diatomaceous earth, 1-1.5 parts activator, and the balance cement, with a total mass of 100 parts. This application uses an activator and steel slag and blast furnace slag powder to prepare a solidification material. The combined effect of these two components can simultaneously improve the early and late strength of the solidified soil. Simultaneously, by modifying the diatomaceous earth, the dispersibility of diatomaceous earth and carbonaceous powder in the cementitious material is improved, enhancing the bonding performance of cement. Utilizing the property that diatomaceous earth and sodium polyacrylate aggregate in the aqueous environment and calcium oxide in cement to form water-insoluble crystalline substances, the strength and water erosion resistance of the solidified soil are improved.

Description

Technical Field

[0001] This invention belongs to the field of roadbed solidification technology, and particularly relates to an additive for solidifying slag and soil and its preparation method. Background Technology

[0002] Solidified soil involves adding admixtures to the soil, which trigger a series of physical and chemical reactions to solidify the soil, improve its physical and mechanical properties, reduce its water sensitivity, and enhance its water stability. Furthermore, the strength of the solidified soil can be adjusted by adding solidifying agents to adapt to on-site construction schedules and meet different engineering requirements. In China, cement, lime, fly ash, and mixtures of these materials are mainly used as solidification materials. However, these traditional solidification materials cannot directly treat naturally occurring acidic soils with high water content and high liquid limit.

[0003] Lime production is energy-intensive and environmentally unfriendly, and it results in poor water stability of the soil it improves, making it prone to secondary mudification. Cement-modified soil suffers from drying shrinkage and cracking. While curing agents are effective in treating high liquid limit clays, their generally high cost limits their application. Furthermore, the high moisture content of high liquid limit clays makes it difficult to mix with curing materials, thus affecting the curing effect.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the present invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The first objective of this invention is to provide an additive for solidifying construction waste, which, when added to construction waste, improves the solidification effect.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0007] An additive for solidifying slag soil comprises, by weight, 15-25 parts mineral admixture, 1-1.5 parts activator, 5-10 parts modified diatomaceous earth, and the balance cement, with a total weight of 100 parts for all components.

[0008] Preferably, the mineral admixture is a mixture of steel slag and slag powder in a mass ratio of 7–8:2–3. The steel slag is dried at 100–120℃ and then ground to obtain a specific surface area greater than 500 m². 2 / kg. Steel slag and slag powder promote the later-stage hydration of cement, while steel slag itself delays the early-stage hydration of cement, resulting in a relatively long induction period. In this application, dihydrate gypsum is used as a component of the activator. The dihydrate gypsum reacts with calcium aluminate hydrate in the cement hydration products to generate needle-like rod-shaped ettringite (AFt), which promotes the early-stage hydration of cement. This combines the activator with the mineral admixture to simultaneously improve the early and later-stage strength of the solidified soil.

[0009] Preferably, the activator is one or more of Ca(OH)₂, gypsum dihydrate, and anhydrous sodium sulfate. Specifically, it is prepared by mixing Ca(OH)₂, gypsum dihydrate, and anhydrous sodium sulfate in a mass ratio of 2:3:0.5. Ca(OH)₂ acts as a calcium ion supplement, releasing calcium ions that flocculate clay particles. Simultaneously, due to the high clay content in the soil, calcium ions can also react with diatomaceous earth and active substances such as SiO₂ and Al₂O₃ in the clay to form a gel compound called CASH. The OH⁻ released by Ca(OH)₂... - Ions neutralize the acidity of the soil and reduce the amount of H+ neutralized by cement. + The consumption of ions provides a favorable alkaline environment for cement hydration, allowing it to proceed fully. Simultaneously, the high pH environment promotes the dissolution of SiO2 and Al2O3 in the clay lattice, forming more gel compounds such as CSH and CASH. Gypsum dihydrate reacts with hydrated calcium aluminate from the cement hydration products to form needle-like rod-shaped ettringite (AFt). The expansion of AFt fills pores, reducing total porosity and decreasing the average pore size of the solidified soil, thus achieving a filling and compacting effect. Anhydrous sodium sulfate provides some SO42-. 2- The ions generate more ettringite and increase the salt concentration in the pore solution, effectively increasing the apparent cohesion of the clay and improving the strength and water stability of the solidified soil.

[0010] Preferably, the modified diatomaceous earth is prepared by mixing diatomaceous earth with sodium polyacrylate, a coupling agent, and carbonaceous powder in a mass ratio of 20–40: 5–8: 1–3: 5–10. Diatomaceous earth has an acidic surface and contains a large number of silanol groups, exhibiting high surface energy and hydrophilicity. This application significantly improves the oleophilicity of the diatomaceous earth surface by adding sodium polyacrylate and a silane coupling agent, thereby enhancing the dispersibility of diatomaceous earth and carbonaceous powder in cementitious materials and improving the bonding performance of cement. Based on this, the present invention modifies diatomaceous earth, utilizing the property that diatomaceous earth and sodium polyacrylate can combine with calcium oxide in cement in an aqueous environment to form water-insoluble crystalline substances, thus increasing the degree of cement hydration and improving curing strength and resistance to water erosion.

[0011] Preferably, the main component of diatomaceous earth is SiO2, with a particle size of 10-80 μm. In this invention, the particle sizes of diatomaceous earth and carbonaceous powder are similar, ensuring a uniform structural distribution of the modified diatomaceous earth after mixing and improving the bonding performance of cement.

[0012] Preferably, the sodium polyacrylate has a viscosity of 400–600 mPa·s and a molecular weight of 2 million–3 million.

[0013] Preferably, the carbonaceous powder is waste fruit tree branches with a particle size ≤74μm. The carbon content of the fruit tree branches is 35% to 50%, and the lignin they contain is a key component of the vascularized plant support tissue. As a high-hardness composite aggregate, it fills the pores of the cementitious material, further improving the strength of the cementitious material in the solidified soil after hardening.

[0014] Preferably, the coupling agent is a silane coupling agent. The silane coupling agent is γ-(methacryloyloxy)propyltrimethoxysilane.

[0015] As a preferred method, the preparation of modified diatomaceous earth includes the following steps:

[0016] (1) Remove the bark from the surface of waste fruit tree branches with a diameter of 5-35 mm, and then place the fruit tree branches outdoors to dry naturally for 1-3 months until the moisture content drops to less than 10%. Then place the crushed fruit tree branches into a 70℃ drying oven and dry them with forced air until constant weight. After drying, crush the fruit tree branches into powder with a particle size ≤1 mm using a pulverizer, then use an ultrafine crusher for fine crushing, and finally grind them and pass them through a 200-mesh sieve to obtain carbon-based powder.

[0017] (2) Weigh out sodium polyacrylate, add 10 times the amount of deionized water, and stir until the sodium polyacrylate is completely dissolved to obtain a sodium polyacrylate solution.

[0018] (3) Mix diatomaceous earth with sodium polyacrylate solution and coupling agent at 50-80℃ for 30 minutes, dry, ball mill for 2 hours, and pass through a 200-mesh sieve to obtain pre-modified diatomaceous earth.

[0019] (4) Mix the carbonaceous powder in (1) with the pre-modified diatomite in (3) evenly to obtain modified diatomite.

[0020] Preferably, the cement is grade PO 42.5.

[0021] The second objective of this invention is to provide a method for preparing an additive for construction waste, which is then added to construction waste to improve the strength of the solidified soil.

[0022] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0023] A method for preparing an additive for solidifying slag and soil includes the following steps:

[0024] S01: Weigh each component according to the mass ratio and set aside;

[0025] S02: Mix mineral admixtures and modified diatomaceous earth evenly to obtain mixture one;

[0026] S03: Add activator and mix evenly, then add cement and mix to obtain curing additive.

[0027] The solidification additive prepared in this application is added to the engineering waste soil. The liquid limit of the engineering waste soil is 61.5 wL / %, and the main chemical components are SiO2, Al2O3, and Fe2O3, with a content of more than 90%. The dosage of the solidification additive is 15%.

[0028] In summary, the present invention has the following beneficial effects:

[0029] This application uses an activator and mineral admixtures (steel slag, slag powder) to prepare a curing material that can simultaneously promote the early and late hydration of cement. Simultaneously, by modifying diatomaceous earth, the dispersibility of diatomaceous earth and carbonaceous powder in the cementitious material is improved, enhancing the cement's bonding performance. Furthermore, utilizing the property that diatomaceous earth and sodium polyacrylate can aggregate with calcium oxide in the cement in an aqueous environment to form water-insoluble crystalline substances, the degree of cement hydration is increased, thereby improving the curing strength and resistance to water erosion. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a component analysis diagram of the engineering waste soil used in Example 1 of the present invention;

[0032] Figure 2 This is a SEM image of the curing additive after it has been added in Example 1 of the present invention. Detailed Implementation

[0033] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific implementation methods, features and effects of an additive for solidification of slag and soil, its preparation method and its application method according to the present invention are described in detail below.

[0034] Sources of raw materials used in the examples:

[0035] Material composition Commercially available steel slag Guizhou Iron and Steel Group Steelmaking Plant Slag powder Jiande City Xin'anjiang Yonghe Plastics Factory diatomite Yu Sheng Sodium polyacrylate Shandong Wanhua Chemical Technology Co., Ltd. γ-(methacryloyloxy)propyltrimethoxysilane Nanjing Quanxi Chemical <![CDATA[Ca(OH)2]]> Suzhou Runjie Environmental Protection New Materials Co., Ltd. Gypsum dihydrate Nantong Haigao Machinery Factory Anhydrous sodium sulfate Heze Chemical cement Dezhou Zhonglian Dam Cement Co., Ltd.

[0036] Example 1

[0037] An additive for solidifying slag and soil comprises, by weight, 25 parts mineral admixture, 1.5 parts activator, 10 parts modified diatomaceous earth, and the balance cement, with a total weight of 100 parts.

[0038] The mineral admixture is a mixture of steel slag and slag powder in a mass ratio of 7:3.

[0039] The activator was prepared by mixing Ca(OH)2, gypsum dihydrate, and anhydrous sodium sulfate in a mass ratio of 2:3:0.5.

[0040] Modified diatomaceous earth is prepared by mixing diatomaceous earth with sodium polyacrylate, coupling agent and carbonaceous powder in a mass ratio of 40:8:2:9.

[0041] The preparation method of modified diatomaceous earth includes the following steps:

[0042] (1) Remove the bark from the surface of waste fruit tree branches with a diameter of 5-35 mm, and then place the fruit tree branches outdoors to dry naturally for 1-3 months until the moisture content drops to less than 10%. Then place the crushed fruit tree branches into a 70℃ drying oven and dry them with forced air until constant weight. After drying, crush the fruit tree branches into powder with a particle size ≤1 mm using a pulverizer, then use an ultrafine crusher for fine crushing, and finally grind them and pass them through a 200-mesh sieve to obtain carbon-based powder.

[0043] (2) Weigh out sodium polyacrylate, add 10 times the amount of deionized water, and stir until the sodium polyacrylate is completely dissolved to obtain a sodium polyacrylate solution.

[0044] (3) The diatomaceous earth was mixed with sodium polyacrylate solution and coupling agent at 60°C for 30 minutes, dried and then ball-milled for 2 hours and passed through a 200-mesh sieve to obtain pre-modified diatomaceous earth.

[0045] (4) Mix the carbonaceous powder in (1) with the pre-modified diatomite in (3) evenly to obtain modified diatomite.

[0046] A method for preparing an additive for solidifying slag and soil includes the following steps:

[0047] S01: Weigh each component according to the mass ratio and set aside;

[0048] S02: Mix mineral admixtures and modified diatomaceous earth evenly to obtain mixture one;

[0049] S03: Add activator and mix evenly, then add cement and mix to obtain curing additive.

[0050] Example 2

[0051] An additive for solidifying slag and soil comprises, by weight, 20 parts mineral admixture, 1.5 parts activator, 5 parts modified diatomaceous earth, and the balance cement, with a total weight of 100 parts.

[0052] The mineral admixture is a mixture of steel slag and slag powder in a mass ratio of 8:2.

[0053] Modified diatomaceous earth is prepared by mixing diatomaceous earth with sodium polyacrylate, coupling agent and carbonaceous powder in a mass ratio of 30:6:2:8.

[0054] The preparation method of modified diatomaceous earth includes the following steps:

[0055] (1) Remove the bark from the surface of waste fruit tree branches with a diameter of 5-35 mm, and then place the fruit tree branches outdoors to dry naturally for 1-3 months until the moisture content drops to less than 10%. Then place the crushed fruit tree branches into a 70℃ drying oven and dry them with forced air until constant weight. After drying, crush the fruit tree branches into powder with a particle size ≤1 mm using a pulverizer, then use an ultrafine crusher for fine crushing, and finally grind them and pass them through a 200-mesh sieve to obtain carbon-based powder.

[0056] (2) Weigh out sodium polyacrylate, add 10 times the amount of deionized water, and stir until the sodium polyacrylate is completely dissolved to obtain a sodium polyacrylate solution.

[0057] (3) The diatomaceous earth was mixed with sodium polyacrylate solution and coupling agent at 70°C for 30 minutes, dried and then ball-milled for 2 hours and passed through a 200-mesh sieve to obtain pre-modified diatomaceous earth.

[0058] (4) Mix the carbonaceous powder in (1) with the pre-modified diatomite in (3) evenly to obtain modified diatomite.

[0059] A method for preparing an additive for solidifying slag and soil includes the following steps:

[0060] S01: Weigh each component according to the mass ratio and set aside;

[0061] S02: Mix mineral admixtures and modified diatomaceous earth evenly to obtain mixture one;

[0062] S03: Add activator and mix evenly, then add cement and mix to obtain curing additive.

[0063] Example 3

[0064] An additive for solidifying slag soil comprises, by weight, 15 parts mineral admixture, 1 part activator, 5 parts modified diatomaceous earth, and the balance cement, with a total weight of 100 parts.

[0065] The mineral admixture is a mixture of steel slag and slag powder in a mass ratio of 7:3.

[0066] Modified diatomaceous earth is prepared by mixing diatomaceous earth with sodium polyacrylate, coupling agent and carbonaceous powder in a mass ratio of 35:7:2:7.

[0067] The preparation method of modified diatomaceous earth includes the following steps:

[0068] (1) Remove the bark from the surface of waste fruit tree branches with a diameter of 5-35 mm, and then place the fruit tree branches outdoors to dry naturally for 1-3 months until the moisture content drops to less than 10%. Then place the crushed fruit tree branches into a 70℃ drying oven and dry them with forced air until constant weight. After drying, crush the fruit tree branches into powder with a particle size ≤1 mm using a pulverizer, then use an ultrafine crusher for fine crushing, and finally grind them and pass them through a 200-mesh sieve to obtain carbon-based powder.

[0069] (2) Weigh out sodium polyacrylate, add 10 times the amount of deionized water, and stir until the sodium polyacrylate is completely dissolved to obtain a sodium polyacrylate solution.

[0070] (3) The diatomaceous earth was mixed with sodium polyacrylate solution and coupling agent at 80°C for 30 minutes, dried and then ball-milled for 2 hours and passed through a 200-mesh sieve to obtain pre-modified diatomaceous earth.

[0071] (4) Mix the carbonaceous powder in (1) with the pre-modified diatomite in (3) evenly to obtain modified diatomite.

[0072] A method for preparing an additive for solidifying slag and soil includes the following steps:

[0073] S01: Weigh each component according to the mass ratio and set aside;

[0074] S02: Mix mineral admixtures and modified diatomaceous earth evenly to obtain mixture one;

[0075] S03: Add activator and mix evenly, then add cement and mix to obtain curing additive.

[0076] Example 4

[0077] An additive for solidifying slag soil comprises, by weight, 25 parts mineral admixture, 1.2 parts activator, 8 parts modified diatomaceous earth, and the balance cement, with a total weight of 100 parts.

[0078] The mineral admixture is a mixture of steel slag and slag powder in a mass ratio of 8:2.

[0079] Modified diatomaceous earth is prepared by mixing diatomaceous earth with sodium polyacrylate, coupling agent and carbonaceous powder in a mass ratio of 20:5:1:5.

[0080] The preparation method of modified diatomaceous earth includes the following steps:

[0081] (1) Remove the bark from the surface of waste fruit tree branches with a diameter of 5-35 mm, and then place the fruit tree branches outdoors to dry naturally for 1-3 months until the moisture content drops to less than 10%. Then place the crushed fruit tree branches into a 70℃ drying oven and dry them with forced air until constant weight. After drying, crush the fruit tree branches into powder with a particle size ≤1 mm using a pulverizer, then use an ultrafine crusher for fine crushing, and finally grind them and pass them through a 200-mesh sieve to obtain carbon-based powder.

[0082] (2) Weigh out sodium polyacrylate, add 10 times the amount of deionized water, and stir until the sodium polyacrylate is completely dissolved to obtain a sodium polyacrylate solution.

[0083] (3) The diatomaceous earth was mixed with sodium polyacrylate solution and coupling agent at 50°C for 30 minutes, dried and then ball-milled for 2 hours and passed through a 200-mesh sieve to obtain pre-modified diatomaceous earth.

[0084] (4) Mix the carbonaceous powder in (1) with the pre-modified diatomite in (3) evenly to obtain modified diatomite.

[0085] A method for preparing an additive for solidifying slag and soil includes the following steps:

[0086] S01: Weigh each component according to the mass ratio and set aside;

[0087] S02: Mix mineral admixtures and modified diatomaceous earth evenly to obtain mixture one;

[0088] S03: Add activator and mix evenly, then add cement and mix to obtain curing additive.

[0089] Comparative Example 1

[0090] An additive for solidifying slag soil comprises, by weight, 50 parts mineral admixture, 1.5 parts activator, 10 parts modified diatomaceous earth, and the balance cement, with a total weight of 100 parts for all components.

[0091] The mineral admixture is a mixture of steel slag and slag powder in a mass ratio of 7:3.

[0092] Modified diatomaceous earth is prepared by mixing diatomaceous earth with sodium polyacrylate, coupling agent and carbonaceous powder in a mass ratio of 40:8:2:9.

[0093] The preparation method of modified diatomaceous earth includes the following steps:

[0094] (1) Remove the bark from the surface of waste fruit tree branches with a diameter of 5-35 mm, and then place the fruit tree branches outdoors to dry naturally for 1-3 months until the moisture content drops to less than 10%. Then place the crushed fruit tree branches into a 70℃ drying oven and dry them with forced air until constant weight. After drying, crush the fruit tree branches into powder with a particle size ≤1 mm using a pulverizer, then use an ultrafine crusher for fine crushing, and finally grind them and pass them through a 200-mesh sieve to obtain carbon-based powder.

[0095] (2) Weigh out sodium polyacrylate, add 10 times the amount of deionized water, and stir until the sodium polyacrylate is completely dissolved to obtain a sodium polyacrylate solution.

[0096] (3) The diatomaceous earth was mixed with sodium polyacrylate solution and coupling agent at 60°C for 30 minutes, dried and then ball-milled for 2 hours and passed through a 200-mesh sieve to obtain pre-modified diatomaceous earth.

[0097] (4) Mix the carbonaceous powder in (1) with the pre-modified diatomite in (3) evenly to obtain modified diatomite.

[0098] A method for preparing an additive for solidifying slag and soil includes the following steps:

[0099] S01: Weigh each component according to the mass ratio and set aside;

[0100] S02: Mix mineral admixtures and modified diatomaceous earth evenly to obtain mixture one;

[0101] S03: Add activator and mix evenly, then add cement and mix to obtain curing additive.

[0102] Comparative Example 2

[0103] An additive for solidifying slag soil comprises, by weight, 25 parts mineral admixture, 1.5 parts activator, and the balance cement, with a total weight of 100 parts.

[0104] The mineral admixture is a mixture of steel slag and slag powder in a mass ratio of 7:3.

[0105] A method for preparing an additive for solidifying slag and soil includes the following steps:

[0106] S01: Weigh each component according to the mass ratio and set aside;

[0107] S02: Add the activator to the mineral admixture and mix evenly, then add cement and mix to obtain a curing additive.

[0108] Comparative Example 3

[0109] An additive for solidifying slag soil comprises, by weight, 5 parts mineral admixture, 1.5 parts activator, 5 parts modified diatomaceous earth, and the balance cement, with a total weight of 100 parts.

[0110] The mineral admixture is a mixture of steel slag and slag powder in a mass ratio of 7:3.

[0111] Modified diatomaceous earth is prepared by mixing diatomaceous earth with sodium polyacrylate, coupling agent and carbonaceous powder in a mass ratio of 40:8:2:9.

[0112] The preparation method of modified diatomaceous earth includes the following steps:

[0113] (1) Remove the bark from the surface of waste fruit tree branches with a diameter of 5-35 mm, and then place the fruit tree branches outdoors to dry naturally for 1-3 months until the moisture content drops to less than 10%. Then place the crushed fruit tree branches into a 70℃ drying oven and dry them with forced air until constant weight. After drying, crush the fruit tree branches into powder with a particle size ≤1 mm using a pulverizer, then use an ultrafine crusher for fine crushing, and finally grind them and pass them through a 200-mesh sieve to obtain carbon-based powder.

[0114] (2) Weigh out sodium polyacrylate, add 10 times the amount of deionized water, and stir until the sodium polyacrylate is completely dissolved to obtain a sodium polyacrylate solution.

[0115] (3) The diatomaceous earth was mixed with sodium polyacrylate solution and coupling agent at 60°C for 30 minutes, dried and then ball-milled for 2 hours and passed through a 200-mesh sieve to obtain pre-modified diatomaceous earth.

[0116] (4) Mix the carbonaceous powder in (1) with the pre-modified diatomite in (3) evenly to obtain modified diatomite.

[0117] A method for preparing an additive for solidifying slag and soil includes the following steps:

[0118] S01: Weigh each component according to the mass ratio and set aside;

[0119] S02: Mix mineral admixtures and modified diatomaceous earth evenly to obtain mixture one;

[0120] S03: Add activator and mix evenly, then add cement and mix to obtain curing additive.

[0121] Performance testing

[0122] The solidification additive prepared in this application was added to the engineering waste soil. The liquid limit of the engineering waste soil was 61.5 wL / %, and its main chemical components were SiO2, Al2O3, and Fe2O3, with a content of over 90%, as follows: Figure 1The image shows the mineral composition analysis of the engineering waste soil in this application, with the solidification additive dosage being 15%.

[0123] Cylindrical specimens (φ50*50mm) were compacted at the optimal moisture content and then bagged and cured in a standard curing room for 7 days. Specimens undergoing water stability testing were immersed in water for 24 hours on the last day. The specimens were then subjected to 7-day unconfined compressive strength and water stability tests.

[0124] serial number Optimal moisture content / % <![CDATA[Maximum dry density g / cm 3 > 7d unconfined strength (MPa) Water stability coefficient % Example 1 27.8 1.579 5.84 72.7 Example 2 28.2 1.566 4.85 59.8 Example 3 28.5 1.561 4.72 58.8 Example 4 28 1.567 4.91 55.35 Comparative Example 1 29 1.553 3.65 47.56 Comparative Example 2 28.3 1.564 3.52 41.73 Comparative Example 3 27.9 1.577 5.25 60.44

[0125] The data shows that the solidification additives used in this application can improve the physical and mechanical properties of the soil, reduce its water sensitivity, and enhance its water stability.

[0126] In Comparative Example 1, an excessive amount of mineral admixtures were used, which partially replaced cement, thus reducing the Ca required for cement hydration. 2+ The absence of ions significantly reduces the strength of the solidified soil, indicating that this application can improve the solidification effect by limiting the proportion of each component.

[0127] In Comparative Example 2, no modified diatomaceous earth was used. The data comparison shows that the maximum dry density was only slightly increased, and the 7-day unconfined strength and water stability coefficient were lower than those in Comparative Example 1. This indicates that the use of modified diatomaceous earth can generate more gel compound CASH and improve the solidification strength of the solidified soil.

[0128] In Comparative Example 3, the cement content was 88.5 parts, accounting for 13.3%, which made it have the best mechanical properties. However, its solidification mainly relied on the cement itself to bind and increase the maximum dry density. Therefore, the compressive strength of the solidified soil was significantly improved, but the water erosion resistance of the solidified soil was not significantly improved, so the water stability coefficient was only slightly improved.

[0129] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An additive for slag solidification, characterized by, The components include 15-25 parts of mineral admixture, 1-1.5 parts of activator, 5-10 parts of modified diatomite, and the balance of cement, the total mass of the components is 100 parts; The modified diatomite is prepared by mixing diatomite, sodium polyacrylate, coupling agent and carbon powder in a mass ratio of 20-40:5-8:1-3:5-10, the carbon powder is waste fruit tree branches with a particle size of ≤74 μm, and the carbon content of the fruit tree branches is 35%-50%.

2. The additive for solidification of sludge according to claim 1, characterized by, The mineral admixture is a mixture of steel slag and slag powder in a mass ratio of 7-8:2-3.

3. The additive for solidification of sludge according to claim 1, characterized by, The activator is one or more of Ca(OH)2, dihydrate gypsum and anhydrous sodium sulfate.

4. The additive for solidification of sludge according to claim 1, characterized by, The main component of the diatomite is SiO2, and the particle size is 10-80 μm.

5. The additive for solidification of sludge according to claim 1, characterized by The viscosity of the sodium polyacrylate is 400-600 mPa·s, and the molecular weight is 2-3 million.

6. The additive for solidification of sludge according to claim 1, wherein The coupling agent is a silane coupling agent.

7. The additive for solidification of sludge according to claim 1, wherein The preparation method of the modified diatomite includes the following operation steps: (1) The waste fruit tree branches with a diameter of 5-35 mm are subjected to surface peeling treatment, and then the fruit tree branches are naturally dried outdoors for 1-3 months to reduce the moisture content to less than 10%, and then the fruit tree branches are crushed into pieces and placed in a 70°C drying oven for air drying to constant weight, the dried fruit tree branches are crushed to a particle size of ≤1 mm by a pulverizer, and then finely crushed by a superfine crusher, and finally ground, and sieved through a 200 mesh sieve to obtain a carbon powder; (2) The sodium polyacrylate is weighed, 10 times the amount of deionized water is added, and stirred until the sodium polyacrylate is completely dissolved to obtain a sodium polyacrylate solution; (3) The diatomite is mixed with the sodium polyacrylate solution and the coupling agent at 50-80°C for 30 minutes, and then dried and ball milled for 2 hours by a ball mill, and sieved through a 200 mesh sieve to obtain a pre-modified diatomite; (4) The carbon powder in (1) is mixed with the pre-modified diatomite in (3) to obtain a modified diatomite.

8. The method of claim 1, wherein the additive for solidification of sludge is prepared by adding the additive to the sludge. The method includes the following steps: S01: each component is weighed according to the mass ratio for standby; S02: the mineral admixture is mixed with the modified diatomite to obtain a mixture one; S03: the activator is added and mixed uniformly, and then the cement is added and mixed to obtain the solidification additive.

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