Solid waste-based curing agent and application thereof

Abstract

The invention relates to a solid-waste-based curing agent and application thereof. The solid-waste-based curing agent comprises metal smelting solid waste, alkaline solid waste and coal-based solid waste according to the mass ratio of (4-7): 2: (1-2.5). The metal smelting solid waste is slag and / or steel slag; the alkaline solid waste is carbide slag; the coal-based solid waste is fly ash and / or coal gangue. According to the invention, common industrial solid wastes are utilized, and through mixing ratio adjustment and proper addition of a small amount of appropriate additives, the application scene requirements of various mucky soil flow state solidification such as foundation pit, comprehensive pipe gallery and pipe groove backfilling, mine and tunnel goaf backfilling, roadbed and pavement base filling, soft foundation treatment and the like can be met.

Description

Technical Field

[0001] This invention relates to a solid waste-based solidifying agent and its application. Background Technology

[0002] Traditional cement-based materials, as the main cementitious materials in the modern construction industry, have long faced the dual challenges of high carbon emissions and high energy consumption. Carbon emissions generated during cement production mainly originate from two sources: first, "process emissions" from the high-temperature calcination (approximately 1450℃) of limestone, accounting for 54%-60% of total emissions; and second, direct emissions from the combustion of fossil fuels for energy supply, accounting for approximately 35%. Statistics show that global cement production accounts for 7.5% of global anthropogenic emissions annually, making it the third largest source of carbon emissions after the power and steel industries.

[0003] Meanwhile, the inefficient utilization of industrial solid waste continues to exacerbate the environmental burden. Taking typical heavy industry as an example, large quantities of iron tailings, slag, and steel slag are generated annually. Their chemical composition is similar to that of cement, but traditional treatment methods mostly rely on landfill or open-air dumping, which not only occupies land resources but also poses a risk of heavy metal leaching. Although research shows that water-quenched slag can be used as a substitute raw material for cement, and that waste cement can be recycled through electric arc furnace regeneration technology, the global comprehensive utilization rate of solid waste is currently less than 30%. Given the current situation of high carbon emissions and inefficient solid waste utilization, the development of new green building materials and the improvement of solid waste resource utilization are urgently needed.

[0004] With the rapid advancement of urban infrastructure construction, the volume of waste soil from municipal works, rail transit, and construction is also increasing significantly. This waste soil primarily originates from tunnel boring machine excavation and foundation pit excavation, and the resulting silty soil is characterized by high water content, low strength, and fluidity. Open-air dumping or landfilling poses environmental pollution, safety hazards, and resource waste. Meanwhile, the traditional cement-based materials used in urban infrastructure construction also present a series of problems, including high carbon emissions and high energy consumption.

[0005] However, existing technologies for solid waste-based cementitious materials for soil solidification have several drawbacks, including high raw material pretreatment costs (such as red mud calcination and marine silt dewatering), complex material systems (cumbersome preparation processes and strict process requirements), limited soil compatibility (such as unsuitability for solidifying silty soil with high water content and inability to achieve fluid solidification of silty soil), and high carbon emissions. Furthermore, the raw materials used as solidifying agents are all too expensive. Summary of the Invention

[0006] The technical problem this invention aims to solve is to overcome at least one of the shortcomings of existing technologies, such as high raw material pretreatment costs, complex material systems, limited soil compatibility, and high carbon emissions, by providing a solid waste-based solidifying agent and its applications. This invention utilizes general industrial solid waste, and through adjustments to the mixing ratio and the appropriate addition of small amounts of suitable additives, it can meet the application requirements of various silty soil fluid solidification scenarios, including backfilling of foundation pits, integrated pipe corridors and trenches, backfilling of mining and tunnel goaf areas, roadbed and pavement base layer filling, and soft soil treatment.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution:

[0008] In a first aspect, the present invention provides a solid waste-based solidifying agent comprising metal smelting solid waste, alkaline solid waste and coal-based solid waste in a mass ratio of (4-7): 2: (1-2.5); wherein the metal smelting solid waste is slag and / or steel slag; the alkaline solid waste is carbide slag; and the coal-based solid waste is fly ash and / or coal gangue.

[0009] In this invention, the solid waste from metal smelting refers to the solid waste generated during the metal smelting process (including dry and wet processes). This solid waste mainly originates from the smelting, refining, and separation of metals, as well as subsequent waste gas and wastewater treatment processes.

[0010] In this invention, alkaline solid waste refers to waste that is alkaline and in solid form, generated during production, use, or disposal. Its alkalinity mainly comes from strong alkalis or alkaline substances such as sodium hydroxide, potassium hydroxide, calcium oxide, and magnesium oxide.

[0011] In this invention, coal-based solid waste refers to solid waste generated throughout the entire chain of coal mining, washing, processing, combustion, and chemical conversion. It includes both primary solid waste—such as coal gangue and coal slime—which are directly generated during the mining and washing stages, and modified solid waste—such as fly ash, bottom ash, and gasification slag—which are formed after high-temperature processes such as combustion or gasification.

[0012] In this invention, the blast furnace slag (GGBFS) refers to the solid waste slag generated during the iron and steel smelting process. The blast furnace slag may contain SiO2, Al2O3, and CaO. The SiO2 content is preferably 25%-40% by mass, more preferably 30%-35%, for example, 34.2%. The Al2O3 content is preferably 5%-20% by mass, more preferably 15%-20%, for example, 17.6%. The CaO content is preferably 30%-50% by mass, more preferably 30%-40%, for example, 34%. The particle size of the blast furnace slag may be 425-575 mesh, for example, 500 mesh.

[0013] In this invention, the steel slag is an oxide formed by the reaction of impurities such as carbon, silicon, manganese, sulfur, and phosphorus discharged during the steelmaking process. The steel slag may contain SiO2, CaO, and Al2O3. The SiO2 content is preferably 10%-35% by mass, more preferably 10%-25%, for example, 12.1%. The CaO content is preferably 30%-60% by mass, more preferably 30%-35%, for example, 31.8%. The Al2O3 content is preferably 1%-15% by mass, more preferably 1%-5%, for example, 4.1%. The particle size of the steel slag may be 125-275 mesh, for example, 200 mesh.

[0014] In this invention, the carbide slag is the solid waste residue left after the hydrolysis of calcium carbide to generate acetylene gas. The carbide slag may contain CaO, Al2O3, and SiO2. Preferably, the mass content of CaO is >60%, more preferably >65%, for example, 67.95%. Preferably, the mass content of SiO2 is 1%-8%, more preferably 1%-5%, for example, 1.53%. Preferably, the mass content of Al2O3 is 0.5%-5%, more preferably 1%-5%, for example, 1.93%. The particle size of the carbide slag may be 125-275 mesh, for example, 200 mesh.

[0015] In this invention, the fly ash is a fine solid particle produced during the combustion process of coal-fired power generation or coal-fired industrial boilers. It is mainly composed of incompletely burned minerals (such as oxides of silicon, aluminum, iron, and calcium), and is a grayish-white or light gray powder. In this invention, the fly ash may contain SiO2, Al2O3, and CaO. The mass content of SiO2 is preferably 30%-60%, more preferably 40%-50%, for example, 43%. The mass content of Al2O3 is preferably 10%-30%, more preferably 20%-30%, for example, 23%. The mass content of CaO is preferably less than or equal to 10%, more preferably less than or equal to 3%, for example, 0.8%. The particle size of the fly ash can be 225-375 mesh, for example, 300 mesh.

[0016] In this invention, coal gangue refers to solid waste generated during coal mining, tunneling, and washing. In this invention, the coal gangue may contain SiO2, Al2O3, and CaO; the mass content of SiO2 is preferably 40%-65%, more preferably 50%-55%, for example 50.4%. The mass content of Al2O3 is preferably 10%-40%, more preferably 25%-30%, for example 29.2%. The mass content of CaO is preferably 1%-10%, more preferably 1%-5%, for example 3.9%. In this invention, the particle size of the coal gangue may be 300-400 mesh, for example 325 mesh.

[0017] In this invention, the mass ratio of the metal smelting solid waste to the alkaline solid waste can be (5-7):2, for example 5.5:2, 6:2 or 7:2.

[0018] In this invention, the mass ratio of the alkaline solid waste to the coal-based solid waste can be 2:(1-2), for example 2:1.5.

[0019] In this invention, the solid waste from metal smelting can be slag and steel slag, and the preferred mass ratio of the slag and the steel slag is (0.5-2):1, for example, 1:1.

[0020] In this invention, the coal-based solid waste can be fly ash and coal gangue, and the preferred mass ratio of fly ash to coal gangue is (0.5-2):1, for example, 1:1.

[0021] In this invention, the solid waste-based solidifying agent can be a solid waste-based solidifying agent applied to the fluid solidification of silty soil.

[0022] In a second aspect, the present invention provides a solid waste-based gel material, comprising silty soil, an additive, water, and a solid waste-based curing agent as described above; the mass of the additive accounts for 0.3%-1% of the mass of the solid waste-based curing agent; the mass ratio of the silty soil to the solid waste-based curing agent is (3-5):1; the additive is a vinyl polyethylene glycol ether-acrylic acid copolymer, a sodium salt of maleic acid-acrylic acid copolymer, or a sodium β-naphthalenesulfonate-formaldehyde condensate.

[0023] In this invention, the silty soil refers to soil formed during natural sedimentation or artificial filling, consisting of a mixture of fine-grained sediments (mainly clay and fine sand) and organic matter. It is a type of soft soil characterized by fine clay particles, high water content, and high compressibility, commonly found in low-lying wetland areas or artificial landfill sites. In this invention, the silty soil may contain SiO2, Al2O3, Fe2O3, CaO, and MgO. The SiO2 content is preferably 65%-70% by mass, for example, 69%. The Al2O3 content is preferably 10%-15% by mass, for example, 12.5%. The Al2O3 content is preferably 5%-10% by mass, for example, 6.17%. The Fe2O3 content is preferably 1%-5% by mass, for example, 3.88%. The water content of the silty soil can be 20%-70%, preferably 25%-30%, for example, 28%. The organic matter content of the silty soil can be 0.5%-1%, for example, 0.8%.

[0024] In some specific embodiments of the present invention, the mass ratio of the metal smelting solid waste, the alkaline solid waste and the coal-based solid waste is (5.5-7): 2: (1-2.5), for example (6-7): 2: (1-1.5).

[0025] In this invention, the mass of the additive may account for 0.6%-0.9% of the mass of the solid waste-based solidifying agent, for example, 0.75%.

[0026] In this invention, the mass ratio of the silty soil to the solid waste-based solidifying agent can be (3.3-4):1.

[0027] In this invention, the mass ratio of water to solid waste-based solidifying agent can be (1.5-2):1, for example, 1.8:1.

[0028] In this invention, the additive can be a polycarboxylate superplasticizer. For example, it can be a high-performance polycarboxylate superplasticizer of type HLX (standard). The pH of the polycarboxylate superplasticizer can be 5-6. The solid content of the polycarboxylate superplasticizer can be 35wt%-45wt%, preferably 35wt%-40wt%, for example 39.7wt%.

[0029] Thirdly, the present invention provides a solid waste-based slurry, comprising an additive, water, and the aforementioned solid waste-based solidifying agent; the additive accounts for 3%-6% of the mass of the solid waste-based solidifying agent; the additive is desulfurized gypsum or silanol.

[0030] In this invention, the desulfurization gypsum (also known as flue gas desulfurization gypsum or FGD gypsum) is a solid byproduct generated after the combustion of sulfur-containing fuels such as coal and oil, using a wet lime-gypsum desulfurization process (FGD) to absorb and oxidize sulfur dioxide in the flue gas. In this invention, the desulfurization gypsum may contain one or more of the following: CaSO4·0.5H2O, SiO2, Al2O3, CaO, sodium oxide, calcium carbonate, and calcium sulfite. Preferably, the mass content of CaSO4·0.5H2O is 70%-95%, more preferably 80%-90%. Preferably, the mass content of SiO2 is less than or equal to 4%, more preferably less than or equal to 1%. Preferably, the mass content of Al2O3 is less than or equal to 2%, more preferably less than or equal to 1%, for example, 0.9%. Preferably, the mass content of CaO is less than or equal to 1%, for example, 0.8%.

[0031] In this invention, the mass of the additive can account for 4%-5% of the mass of the solid waste-based solidifying agent.

[0032] In this invention, the mass ratio of water to solid waste-based solidifying agent can be (0.8-2):1, for example 0.8:1, 0.82:1, 0.84:1, 0.88:1, 1:1, 1.64:1 or 2:1.

[0033] In this invention, the silanol salt is sodium silanolate and / or sodium methylsilanolate.

[0034] In this invention, the additive can be an organosilicon waterproofing agent. The pH value of the organosilicon waterproofing agent can be ≥13.

[0035] Thirdly, the present invention provides an application of a solid waste-based solidifying agent, which is applied to the fluid solidification of silty soil; the fluid solidification of the silty soil is carried out by backfilling, roadbed filling or soft soil treatment; the backfilling is carried out using the solid waste-based gel material as described above; the roadbed filling or soft soil treatment is carried out using the solid waste-based slurry as described above.

[0036] In this invention, the fluidized solidification of silty soil (also known as fluidized solidified soil) refers to the process of pumping and pouring soft silty soil with high water content and low strength in a fluid state, and then gradually hardening it into a solid soil with certain strength and water resistance during the curing process.

[0037] In this invention, backfilling refers to transforming the engineering waste soil obtained on-site into a fluid liquid mixture; after pouring, it rapidly hardens through a physical-chemical curing reaction, ultimately resulting in a solidified soil body with controllable strength, impermeability, and low settlement.

[0038] In this invention, the roadbed filling refers to adding a curing agent directly to the soft soil or weak foundation on-site, and using a special mixing device to fully mix the curing agent with the soil, so that the soil forms a "hard shell layer" with high strength and low permeability in situ.

[0039] In this invention, the soft soil treatment refers to injecting a low-flowability, high-concentration grout into the soil. The grout forms "bubbles" at the orifice, which, through compression, compact the surrounding soil particles and eliminate pores, thereby increasing the soil density and strength.

[0040] In this invention, the backfilling scenario can be a foundation pit, pipe gallery, pipe trench, mine goaf, or tunnel goaf.

[0041] In this invention, the scenario of roadbed filling can be the roadbed or the bottom of the road base.

[0042] In this invention, during the roadbed filling, the mass ratio of the silty soil to the solid waste-based solidifying agent can be (10-20):1, for example, 10:1.

[0043] In this invention, during the soft soil treatment, the mass ratio of the silty soil to the solid waste-based solidifying agent can be (10-20):1, for example, 20:1.

[0044] Without violating common sense in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0045] The positive and progressive effects of this invention are as follows:

[0046] (1) The curing agent of the present invention utilizes a high proportion of various industrial solid wastes, discards silica fume, fiber and chemical expansion agent, which can greatly reduce the stockpiling and discharge of solid wastes, and also eliminates the need for the traditional cement-based material-related "two grinding and one burning" process. The carbon emission factor is significantly reduced, effectively reducing the negative impact on the environment and reducing energy consumption.

[0047] (2) The curing agent of the present invention utilizes a high proportion of various industrial solid wastes. Compared with traditional cement-based materials, it can reduce production costs, not only achieving "waste treatment with waste", but also solving the problem of difficult disposal of large amounts of silty soil.

[0048] (3) The curing agent of the present invention has a wide range of applications, including backfilling of foundation pits, integrated pipe corridors and pipe trenches, backfilling of mining and tunnel goaf areas, roadbed filling, soft soil treatment, etc., and has broad application prospects.

[0049] (4) The curing agent of the present invention is a mixture of various industrial solid wastes in a specific ratio, which makes it have good mechanical properties, durability and long-term performance when finally applied, and can meet the application requirements in the fields of soil solidification. Detailed Implementation

[0050] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0051] The specific information of the raw materials used in the following examples and comparative examples is as follows. Unless otherwise specified, the content % in this invention refers to the mass content.

[0052] The silty soil, taken from the Shanghai Pudong Airport area, consists of SiO2, Al2O3, Fe2O3, CaO, and MgO. By mass percentage, its SiO2 content is 69.0%, Al2O3 content is 12.5%, CaO content is 6.17%, and Fe2O3 content is 3.88%. Its physical properties are shown in the table below (mass percentage).

[0053]

[0054] Slag: 500-mesh S95 grade slag powder, purchased from Jiewei Environmental Protection Materials, with SiO2 content of 34.2%, Al2O3 content of 17.6%, and CaO content of 34.0%.

[0055] Steel slag: Grade 1 steel slag powder with a mesh size of 200, purchased from Jiewei Environmental Protection Materials, with a SiO2 content of 12.1%, a CaO content of 31.8%, and an Al2O3 content of 4.1%.

[0056] Fly ash: 300 mesh Class F low-calcium fly ash, purchased from Jiewei Environmental Protection Materials, with SiO2 content of 43.0%, Al2O3 content of 23.0%, and CaO content of 0.8%.

[0057] Finely ground coal gangue: 325 mesh coal gangue powder, purchased from Jiewei Environmental Protection Materials, with SiO2 content of 50.4%, Al2O3 content of 29.2%, and CaO content of 3.9%.

[0058] Carbide slag: 200-mesh carbide slag, purchased from Jiewei Environmental Protection Materials, with a CaO content of 67.95%, SiO2 content of 1.53%, and Al2O3 content of 1.93%. Cement: PO 42.5 ordinary Portland cement, purchased from Shanghai Huilv E-commerce Co., Ltd.

[0059] The polycarboxylate high-performance water-reducing agent, model HLX (standard type), is a transparent or pale yellow liquid. Its main component is a copolymer of vinyl-polyoxyethylene ether and acrylic acid, with a mass ratio of vinyl-polyoxyethylene ether to acrylic acid of approximately 12.86:1. It has a slightly acidic odor, a pH value of 6.0, and a solid content of 39.7%. It was purchased from Shanxi Feike New Materials Co., Ltd.

[0060] Sodium polyacrylate, a white powder or granules, is a polymer compound with hydrophilic and hydrophobic groups, purchased from Shandong Yousuo Chemical Technology Co., Ltd.

[0061] Sodium hexametaphosphate, in colorless and transparent glass flake form, with a specific gravity of 2.484 (20℃), was purchased from Shandong Yousuo Chemical Technology Co., Ltd.

[0062] BASF PA25 CL FR is a sodium salt of a water-soluble polymer compound—maleic acid-acrylic acid copolymer—with a content of 45%. It appears as a colorless or pale yellow viscous liquid or gel, and is readily soluble in water. It was purchased from Zhejiang Sandu Chemical Co., Ltd.

[0063] Naphthalene-based water-reducing agent, model FDN-C, is a yellow-brown powder. Its core active ingredient is sodium β-naphthalenesulfonate-formaldehyde condensate, which is easily soluble in water. It has stable physicochemical properties, good performance, and good dispersibility. It was purchased from Shandong Yousuo Chemical Technology Co., Ltd.

[0064] Sodium lignosulfonate, model 215F, is a brown powder that is easily soluble in water. It was purchased from Zhejiang Sandu Chemical Co., Ltd.

[0065] Calcium lignosulfonate, model CA45, is a pale yellow to dark brown powder, purchased from Zhejiang Sandu Chemical Co., Ltd.

[0066] Desulfurized gypsum is a slightly yellow powdery solid, with CaSO4·0.5H2O as its main component, accounting for 90%. It differs from ordinary gypsum powder in its physical composition. Desulfurized gypsum powder also contains silicon dioxide, sodium oxide, calcium carbonate, calcium sulfite, etc., with SiO2 content of 1.0%, Al2O3 content of 0.9%, and CaO content of 0.8%. It was purchased from Hongguan Gypsum Enterprise Store.

[0067] Quicklime is a white granular or powdery substance with a CaO content ≥98.0%. The product was purchased from Tianjin Juhengda Chemical Co., Ltd.

[0068] The instant-dissolving water glass has a modulus of 3.0 and a molecular formula of Na2O·3SiO2. It appears as a white powdery solid and was purchased from Henan Huifeng New Materials Co., Ltd.

[0069] Anhydrous sodium carbonate, white powder, readily soluble in water, its aqueous solution is alkaline, with a Na2CO3 content ≥99.8%, was purchased from Tianjin Zhiyuan Chemical Reagent Co., Ltd.

[0070] The organosilicon waterproofing agent, whose main components are sodium methylsilanolate and high-boiling sodium silanolate, is a colorless or pale yellow transparent liquid with a pH value ≥13 and a specific gravity of 1.1-1.3. It has excellent durability and is sourced from Shandong Yousuo Chemical Technology Co., Ltd.

[0071] Example 1: Solid waste-based gel material for backfilling

[0072] Specific backfilling scenarios include foundation pits, pipe galleries, pipe trenches, mine goaf areas, and tunnel goaf areas. Specific formulations are as follows:

[0073] Example 1-1

[0074] Mix 0.875 kg of slag, 0.875 kg of steel slag, 0.5 kg of carbide slag, 0.125 kg of fly ash, and 0.125 kg of finely ground coal gangue (mass ratio 35: 35: 20: 5: 5) to form a solid waste-based silty soil solidifying agent.

[0075] Mix the above-mentioned curing agent with 10 kg of silty soil, and then add 0.01875 kg of polycarboxylate high-performance water-reducing agent (accounting for 0.75% of the above-mentioned curing agent).

[0076] Then, 4.5 kg of water (1.8 times the amount of the above-mentioned curing agent) is added, and after stirring evenly, a solid waste-based gel material for backfilling fluidized solidified soil is obtained, which can be transported by pumping.

[0077] Examples 1-2

[0078] The difference from Example 1-1 is that the additive in the solid waste-based gel material is replaced with BASF PA25CL FR.

[0079] Examples 1-3

[0080] The difference from Example 1-1 is that the additives in the solid waste-based gel material are replaced with naphthalene-based water-reducing agents.

[0081] Examples 1-4

[0082] The difference from Example 1-1 is that the curing agent is replaced with 0.75 kg slag, 0.75 kg steel slag, 0.5 kg carbide slag, 0.25 kg fly ash, and 0.25 kg ground coal gangue (mass ratio of 30: 30: 20: 10: 10).

[0083] Examples 1-5

[0084] The difference from Example 1-1 is that the curing agent is replaced with 0.6875 kg slag, 0.6875 kg steel slag, 0.5 kg carbide slag, 0.3125 kg fly ash, and 0.3125 kg ground coal gangue (mass ratio of 27.5: 27.5: 20: 12.5:12.5).

[0085] Comparative Example 1-1

[0086] The difference from Example 1-1 is that no additives are added to the solid waste-based gel material.

[0087] Comparative Examples 1-2

[0088] The main difference between this traditional cement-based gel material and Example 1-1 is that the curing agent is replaced with 1.875 kg of cement and 0.625 kg of fly ash (in a mass ratio of 3:1), and no admixtures are used.

[0089] Comparative Examples 1-3

[0090] The difference from Example 1-1 is that the curing agent is replaced with 0.85 kg slag, 0.85 kg steel slag, 0.8 kg carbide slag, 0 kg fly ash, and 0 kg ground coal gangue (mass ratio of 34: 34: 32: 0: 0).

[0091] Comparative Examples 1-4

[0092] The difference from Example 1-1 is that the additive in the solid waste-based gel material is replaced with sodium hexametaphosphate.

[0093] Comparative Examples 1-5

[0094] The difference from Example 1-1 is that the additives in the solid waste-based gel material are replaced with sodium polyacrylate.

[0095] Comparative Examples 1-6

[0096] The difference from Example 1-1 is that the additive in the solid waste-based gel material is replaced with sodium lignosulfonate 215F.

[0097] Comparative Examples 1-7

[0098] The difference from Example 1-1 is that the additive in the solid waste-based gel material is replaced with calcium lignosulfonate CA45.

[0099] The allocation ratios of each group in Example 1 are summarized in the table below.

[0100]

[0101] Example 1: Backfill Performance Prediction

[0102] 1. Test subjects: All gel materials in Example 1.

[0103] 2. Testing standards: The test methods for fluidity and compressive strength shall be in accordance with the Technical Specification for Application of Self-Compacting Concrete JGJ / T 283-2012 and the Standard for Geotechnical Test Methods GB / T 50123, respectively.

[0104] 3. Test results: See the table below.

[0105]

[0106] In Comparative Examples 1-2, using traditional cement-based materials, the predicted backfill performance showed a 3-day strength of only 0.5 MPa, a 28-day strength of only 1.5 MPa, and a flowability of only 150 mm, which failed to meet the relevant performance requirements. In Comparative Examples 1-3, no fly ash was added. Although it had some advantages in strength, it still could not meet the backfill performance requirements, and its later strength growth was low. In Comparative Examples 1-4, sodium hexametaphosphate was used as an admixture. The resulting solid waste-based gel material had low compressive strength and poor flowability, failing to meet the backfill performance requirements.

[0107] In Example 1, a variety of admixtures were selected for comparison. It was found that polycarboxylate superplasticizer was more suitable as an admixture for backfilling. Its fluidity can reach 200 mm, and it can be used for backfilling in narrow and irregular areas (such as foundation pits and trenches). No vibration is required. At the same time, BASF PA25 CL FR and naphthalene-based superplasticizers also have better performance as admixtures.

[0108] Application Example 1: Backfilling

[0109] Specific backfilling scenarios include foundation pits, pipe galleries, pipe trenches, mine goaf areas, and tunnel goaf areas, as detailed below:

[0110] The solid waste-based gel material in Example 1 is transported to the foundation pit, pipe gallery, pipe trench, mining goaf, or tunnel goaf using a concrete mixer truck for pouring and backfilling. During the pouring process, it should start from one end and proceed continuously, pouring in layers, and utilizing its fluidity to allow it to self-level.

[0111] In summary, this invention utilizes locally sourced materials, including on-site construction waste and industrial solid waste, resulting in low cost and compliance with low-carbon and environmentally friendly principles.

[0112] Example 2: Solid waste-based slurry for roadbed filling

[0113] The application of roadbed filling is generally applied to the bottom of the roadbed (soil layer) or the base course (cement layer). The specific formula is as follows:

[0114] Example 2-1

[0115] Mix 0.275 kg of slag, 0.275 kg of steel slag, 0.2 kg of calcium carbide slag, 0.125 kg of fly ash, and 0.125 kg of finely ground coal gangue (mass ratio 27.5: 27.5: 20: 12.5: 12.5) evenly to form a solid waste-based silty soil solidifying agent.

[0116] Add 0.05 kg of desulfurized gypsum (accounting for 5% of the total mass of the above curing agent), then add 0.84 kg of water (accounting for 84% of the total mass of the above curing agent), mix evenly, and obtain solid waste slurry for roadbed filling.

[0117] Example 2-2

[0118] Mix 0.35 kg of slag, 0.35 kg of steel slag, 0.2 kg of carbide slag, 0.05 kg of fly ash, and 0.05 kg of finely ground coal gangue (in a mass ratio of 35:35:20:5:5) evenly to form a solid waste-based silty soil solidifying agent.

[0119] Add 0.05 kg of desulfurized gypsum (accounting for 5% of the total mass of the above curing agent), then add 0.88 kg of water (accounting for 88% of the total mass of the above curing agent), mix evenly, and obtain solid waste slurry for roadbed filling.

[0120] Comparative Example 2-1

[0121] Using traditional cement-based materials, 0.75 kg of cement and 0.25 kg of fly ash are mixed evenly, and then 1 kg of water is added and mixed evenly to obtain a slurry.

[0122] Comparative Example 2-2

[0123] Mix 0.2 kg of slag, 0.2 kg of steel slag, 0.3 kg of carbide slag, 0.1 kg of fly ash, and 0.1 kg of finely ground coal gangue (in a mass ratio of 20:20:30:10:10) evenly to form a solidifying agent.

[0124] Add 0.1 kg of desulfurized gypsum (accounting for 10% of the total mass of the above curing agent), then add 0.8 kg of water (accounting for 80% of the total mass of the above curing agent), mix well, and obtain a slurry.

[0125] Comparative Examples 2-3

[0126] Mix 0.2 kg of slag, 0.2 kg of steel slag, 0.3 kg of carbide slag, 0.1 kg of fly ash, and 0.1 kg of finely ground coal gangue (in a mass ratio of 20:20:30:10:10) evenly to form a solidifying agent.

[0127] Add 0.05 kg of desulfurized gypsum (accounting for 5% of the total mass of the above curing agent), then add 0.76 kg of water (accounting for 76% of the total mass of the above curing agent), mix well, and obtain a slurry.

[0128] Comparative Examples 2-4

[0129] Mix 0.2 kg of slag, 0.2 kg of steel slag, 0.3 kg of carbide slag, 0.1 kg of fly ash, and 0.1 kg of finely ground coal gangue (in a mass ratio of 20:20:30:10:10) evenly to form a solidifying agent.

[0130] Add 0.1 kg of quicklime (accounting for 11% of the total mass of the above curing agent), then add 0.8 kg of water (accounting for 80% of the total mass of the above curing agent), mix well, and obtain the slurry.

[0131] Comparative Examples 2-5

[0132] Mix 0.2 kg of slag, 0.2 kg of steel slag, 0.3 kg of carbide slag, 0.1 kg of fly ash, and 0.1 kg of finely ground coal gangue (in a mass ratio of 20:20:30:10:10) evenly to form a solidifying agent.

[0133] Add 0.05 kg of quicklime and 0.05 kg of water glass (totaling 11% of the total mass of the curing agent), then add 0.8 kg of water (totaling 80% of the total mass of the curing agent), mix well, and obtain the slurry.

[0134] Comparative Examples 2-6

[0135] Mix 0.2 kg of slag, 0.2 kg of steel slag, 0.3 kg of carbide slag, 0.1 kg of fly ash, and 0.1 kg of finely ground coal gangue (in a mass ratio of 20:20:30:10:10) evenly to form a solidifying agent.

[0136] Add 0.05 kg of quicklime and 0.05 kg of anhydrous sodium carbonate (totaling 11% of the total mass of the curing agent), then add 0.8 kg of water (totaling 80% of the total mass of the curing agent), mix well, and obtain the slurry.

[0137] Comparative Examples 2-7

[0138] Mix 0.35 kg of slag, 0.35 kg of steel slag, 0.2 kg of carbide slag, 0.05 kg of fly ash, and 0.05 kg of finely ground coal gangue (in a mass ratio of 35:35:20:5:5) evenly to form a solidifying agent.

[0139] Then add 0.8 kg of water (accounting for 80% of the total mass of the above curing agent), mix well, and obtain the slurry.

[0140] Comparative Examples 2-8

[0141] Mix 0.25 kg of slag, 0.25 kg of steel slag, 0.4 kg of carbide slag, 0.05 kg of fly ash, and 0.05 kg of finely ground coal gangue (in a mass ratio of 25:25:40:5:5) evenly to form a solidifying agent.

[0142] Then add 0.8 kg of water (accounting for 80% of the total mass of the above curing agent), mix well, and obtain the slurry.

[0143] The allocation ratios of each group in Example 2 are summarized in the table below.

[0144]

[0145] Example 2: Prediction of In-situ Solidification and Stabilization Performance of Roadbed Filling

[0146] 1. Test objects: all the slurries in Example 2.

[0147] 2. Testing Method:

[0148] (1) Operation process: In order to predict the in-situ solidification and stabilization of the product in Example 2 after the roadbed filling, 10 kg of silty soil (10 times the mass of the solidifying agent) was added to the slurry to obtain the gel material, and its performance was tested.

[0149] (2) Testing standards: "Specifications for Testing Geotechnical Engineering for Highways" (JTG E40) and "Specifications for Testing Inorganic Binder Stabilized Materials for Highway Engineering" (JTG E51).

[0150] 3. Test results: See the table below.

[0151]

[0152] In Comparative Example 2-1, using traditional cement-based materials, the 7-day unconfined compressive strength was only 1.8 MPa, and the CBR value was 65%. In Comparative Examples 2-4 and 2-5, quicklime and fast-dissolving water glass were used as admixtures, respectively, resulting in lower compressive strength and CBR values, making them unsuitable for in-situ solidification and stabilization of roadbeds.

[0153] In Example 2, by adjusting the proportions of various solid wastes and selecting a suitable admixture, desulfurized gypsum, a material with superior performance can be obtained. Based on this, the silty soil solidifier prepared in Example 2 can be applied to in-situ solidification and stabilization of roadbeds, exhibiting good solidification effects.

[0154] Application Example 2: Roadbed Filling

[0155] The application of roadbed filling is generally to the bottom of the roadbed (soil layer) or the base course (cement layer), as detailed below:

[0156] The slurry prepared in Example 2 is pumped to a high-powered mixing head and mixed with the in-situ silty soil while being solidified and advanced to fill the roadbed or the bottom of the road base. The silty soil is about 10 times the mass of the solidifying agent.

[0157] In summary, the silty soil solidifier of this invention can be applied to roadbed filling, and still has good solidification effect even with low admixture dosage. The in-situ soil mixing and solidification method results in high construction efficiency and speed, significantly shortening the setting time of the solidified soil layer (1-2 days earlier than traditional cement-based materials), which is beneficial to the progress of construction.

[0158] Example 3: Solid waste-based slurry for soft soil treatment

[0159] Example 3-1

[0160] Mix 0.15 kg of slag, 0.15 kg of steel slag, 0.1 kg of carbide slag, 0.05 kg of fly ash, and 0.05 kg of finely ground coal gangue (in a mass ratio of 30:30:20:10:10) evenly to form a solid waste-based silty soil solidifying agent.

[0161] Add 0.025 kg of silicone waterproofing agent (5% of the total mass of the curing agent). Then add 0.82 kg of water (1.64 times the total mass of the curing agent) and mix well to form a solid waste slurry for soft soil treatment.

[0162] Example 3-2

[0163] Mix 0.175 kg of slag, 0.175 kg of steel slag, 0.1 kg of carbide slag, 0.025 kg of fly ash, and 0.025 kg of finely ground coal gangue (mass ratio 35: 35: 20: 5: 5) evenly to form a solid waste-based silty soil solidifying agent.

[0164] Add 0.025 kg of silicone waterproofing agent (5% of the total mass of the curing agent). Then add 1 kg of water (twice the total mass of the curing agent) and mix well to form a solid waste slurry for soft soil treatment.

[0165] Example 3-3

[0166] Mix 0.1375 kg of slag, 0.1375 kg of steel slag, 0.1 kg of calcium carbide slag, 0.0625 kg of fly ash, and 0.0625 kg of finely ground coal gangue (mass ratio 27.5: 27.5: 20: 12.5: 12.5) evenly to form a solid waste-based silty soil solidifying agent.

[0167] Add 0.025 kg of silicone waterproofing agent (5% of the total mass of the curing agent). Then add 1 kg of water (twice the total mass of the curing agent) and mix well to form a solid waste slurry for soft soil treatment.

[0168] Comparative Example 3-1

[0169] Using traditional cement-based materials, 0.75 kg of cement and 0.25 kg of fly ash are mixed evenly, and then 1 kg of water is added and mixed evenly to obtain a slurry.

[0170] The allocation ratios of each group in Example 3 are summarized in the table below.

[0171]

[0172] Example 3: Performance Prediction of Soft Foundation Treatment

[0173] 1. Test objects: all the slurries in Example 3.

[0174] 2. Testing Method:

[0175] (1) Operation process: In order to predict the use of the product in soft soil treatment in Example 3, 10 kg of silty soil (20 times the mass of the above-mentioned curing agent) was added to the solid waste base slurry to obtain gel material, and its performance was tested.

[0176] (2) Testing standard: Code for Geotechnical Investigation (GB 50021).

[0177] 3. Test results: See the table below.

[0178] 7-day test results

[0179]

[0180] 28-day test results

[0181]

[0182] Application Example 3: Soft Foundation Treatment

[0183] The slurry prepared in Example 3 is injected into the silty soil soft base layer through pre-set boreholes using a press to fill voids and compact the soil. The silty soil is approximately 20 times the mass of the solidifying agent.

[0184] Therefore, the curing agent of this invention exhibits better curing effect than cement-based materials in soft soil treatment, and still maintains excellent mechanical properties even with low admixture dosage. The invention offers simple and flexible post-construction construction, with no dust or noise generated during the process, making it environmentally friendly and pollution-free. It can adapt to complex geological formations and has a wide range of applications (such as foundation reinforcement, underground seepage prevention, and foundation pit support). After construction, it demonstrates excellent mechanical properties, stable quality, and forms a continuous integral structure with strong impermeability and minimal post-construction settlement, far lower than that of cement-based materials under the same conditions.

Claims

1. A solid waste-based solidifying agent, characterized in that, It includes solid waste from metal smelting, alkaline solid waste and coal-based solid waste in a mass ratio of (4-7): 2: (1-2.5); the solid waste from metal smelting is slag and / or steel slag; the alkaline solid waste is carbide slag; and the coal-based solid waste is fly ash and / or coal gangue.

2. The solid waste-based solidifying agent as described in claim 1, characterized in that, It meets one or more of the following conditions: (1) The mass ratio of the metal smelting solid waste to the alkaline solid waste is (5-7): 2, for example 5.5: 2, 6: 2 or 7: 2; (2) The mass ratio of the alkaline solid waste to the coal-based solid waste is 2:(1-2), for example 2:1.5; (3) The solid waste from metal smelting is slag and steel slag, and the mass ratio of the slag and the steel slag is preferably (0.5-2):1, for example 1:1; (4) The coal-based solid waste is fly ash and coal gangue, and the mass ratio of fly ash to coal gangue is preferably (0.5-2):1, for example 1:

1.

3. The solid waste-based solidifying agent as described in claim 1, characterized in that, It meets one or more of the following conditions: (1) The slag contains SiO2, Al2O3 and CaO; the mass content of SiO2 is preferably 25%-40%, more preferably 30%-35%, for example 34.2%; the mass content of Al2O3 is preferably 5%-20%, more preferably 15%-20%, for example 17.6%; the mass content of CaO is preferably 30%-50%, more preferably 30%-40%, for example 34%; (2) The steel slag contains SiO2, CaO and Al2O3; the mass content of SiO2 is preferably 10%-35%, more preferably 10%-25%, for example 12.1%; the mass content of CaO is preferably 30%-60%, more preferably 30%-35%, for example 31.8%; the mass content of Al2O3 is preferably 1%-15%, more preferably 1%-5%, for example 4.1%; (3) The carbide slag contains CaO, Al2O3 and SiO2; the mass content of CaO is preferably >60%, more preferably >65%, for example 67.95%; the mass content of SiO2 is preferably 1%-8%, more preferably 1%-5%, for example 1.53%; the mass content of Al2O3 is preferably 0.5%-5%, more preferably 1%-5%, for example 1.93%; (4) The fly ash contains SiO2, Al2O3 and CaO; the mass content of SiO2 is preferably 30%-60%, more preferably 40%-50%, for example 43%; the mass content of Al2O3 is preferably 10%-30%, more preferably 20%-30%, for example 23%; the mass content of CaO is preferably less than or equal to 10%, more preferably less than or equal to 3%, for example 0.8%; (5) The coal gangue contains SiO2, Al2O3 and CaO; the mass content of SiO2 is preferably 40%-65%, more preferably 50%-55%, for example 50.4%; the mass content of Al2O3 is preferably 10%-40%, more preferably 25%-30%, for example 29.2%; the mass content of CaO is preferably 1%-10%, more preferably 1%-5%, for example 3.9%; (6) The particle size of the coal gangue is 300-400 mesh, for example 325 mesh.

4. A solid waste-based gel material, characterized in that, It comprises silty soil, additives, water, and a solid waste-based solidifying agent as described in any one of claims 1-3; the mass of the additives accounts for 0.3%-1% of the mass of the solid waste-based solidifying agent; the mass ratio of the silty soil to the solid waste-based solidifying agent is (3-5):1; the additives are vinyl polyethylene glycol ether-acrylic acid copolymer, sodium salt of maleic acid-acrylic acid copolymer, or sodium β-naphthalenesulfonate-formaldehyde condensate.

5. The solid waste-based gel material as described in claim 4, characterized in that, It meets one or more of the following conditions: (1) The mass ratio of the metal smelting solid waste, the alkaline solid waste and the coal-based solid waste is (5.5-7): 2: (1-2.5), for example (6-7): 2: (1-1.5); (2) The mass of the additive accounts for 0.6%-0.9% of the mass of the solid waste-based solidifying agent, for example, 0.75%; (3) The mass ratio of the silty soil to the solid waste-based solidifying agent is (3.3-4):1; (4) The mass ratio of the water to the solid waste-based solidifying agent is (1.5-2):1, for example, 1.8:1; (5) The silty soil contains SiO2, Al2O3, Fe2O3, CaO and MgO; the mass content of SiO2 is preferably 65%-70%, for example 69%; the mass content of Al2O3 is preferably 10%-15%, for example 12.5%; the mass content of Al2O3 is preferably 5%-10%, for example 6.17%; the mass content of Fe2O3 is preferably 1%-5%, for example 3.88%; (6) The moisture content of the silty soil is 20%-70%, preferably 25%-30%, for example 28%; (7) The organic matter content of the silty soil is 0.5%-1%, for example 0.8%.

6. A solid waste-based slurry, characterized in that, It includes an additive, water, and a solid waste-based solidifying agent as described in any one of claims 1-3; the additive accounts for 3%-6% of the mass of the solid waste-based solidifying agent; the additive is desulfurized gypsum or silanol.

7. The solid waste-based slurry as described in claim 6, characterized in that, It meets one or more of the following conditions: (1) The mass of the additive accounts for 4%-5% of the mass of the solid waste-based solidifying agent; (2) The mass ratio of water to solid waste-based solidifying agent is (0.8-2):1, for example 0.8:1, 0.82:1, 0.84:1, 0.88:1, 1:1, 1.64:1 or 2:1; (3) The desulfurized gypsum contains one or more of CaSO4·0.5H2O, SiO2, Al2O3, CaO, sodium oxide, calcium carbonate, and calcium sulfite; the mass content of CaSO4·0.5H2O is preferably 70%-95%, more preferably 80%-90%; the mass content of SiO2 is preferably less than or equal to 4%, more preferably less than or equal to 1%; the mass content of Al2O3 is preferably less than or equal to 2%, more preferably less than or equal to 1%, for example 0.9%; the mass content of CaO is preferably less than or equal to 1%, for example 0.8%. (4) The silanol salt is sodium silanolate and / or sodium methylsilanolate.

8. An application of a solid waste-based solidifying agent, characterized in that, It is applied to the fluid solidification of silty soil; the fluid solidification of silty soil is carried out by backfilling, roadbed filling or soft soil treatment; The backfilling is carried out using the solid waste-based gel material as described in claim 4 or 5; the roadbed filling or the soft soil treatment is carried out using the solid waste-based slurry as described in claim 6 or 7.

9. The application of the solid waste-based solidifying agent as described in claim 8, characterized in that, It meets one or two of the following conditions: (1) When the roadbed is filled, the mass ratio of the silty soil to the solid waste-based solidifying agent is (10-20): 1, for example, 10: 1; (2) During the soft soil treatment, the mass ratio of the silty soil to the solid waste base solidifying agent is (10-20): 1, for example, 20:

1.

10. The application of the solid waste-based solidifying agent as described in claim 8, characterized in that, It meets one or two of the following conditions: (1) The backfilling scenario is a foundation pit, pipe gallery, pipe trench, mining goaf or tunnel goaf; (2) The scenario of roadbed filling is the roadbed or the bottom of the road base.

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