A composite grouting material and a preparation method thereof

Abstract

This invention discloses a composite grouting material comprising the following components in parts by weight: 80-92 parts of dual-source solid waste aggregate; 0.5-3 parts of nano-activator; 5-10 parts of biomineralizing bacterial solution; 2-5 parts of organic coating agent; and 0.5-2 parts of auxiliary modifier. The dual-source solid waste aggregate includes undisturbed soil from tunnel boring machines and construction waste sand. The nano-activator includes nano-silica sol and graphene oxide. The biomineralizing bacterial solution includes urease-producing microorganisms and a cementing solution. The organic coating agent is an ethylene-vinyl acetate copolymer. The auxiliary modifier includes a rheology modifier and a pH buffer. This invention also discloses a method for preparing the composite grouting material. The composite grouting material provided by this invention constructs a grouting system that is "non-inorganic cementing, undisturbed slag without calcination, and high in solid waste". It clarifies the four-fold synergistic cementing mechanism of "nano-activation-biomineralization-organic coating-skeleton locking", breaks the traditional framework of "inorganic cementing and calcination to enhance activity", and provides a brand-new technical route for water erosion resistant and low-energy-consumption materials for grouting engineering.

Description

Technical Field

[0001] This invention relates to the field of grouting materials technology, specifically to a composite grouting material and its preparation method; more specifically, to a non-inorganic cementitious high solid waste content green intelligent composite grouting material and its preparation method. Background Technology

[0002] Grouting materials are widely used in tunnel lining backfilling, foundation reinforcement, slope stabilization, and underground engineering seepage prevention. Traditional grouting materials are mainly cement-based inorganic binders, which have high early strength, but still reveal many problems during long-term service.

[0003] Firstly, traditional grouting materials are based on inorganic cementitious materials such as cement, steel slag, and mineral slag. Their hydration products (Ca(OH)2, CSH gel) are prone to dissolution and carbonization when immersed in groundwater (containing chloride ions, sulfates, etc.) for extended periods, leading to grout cracking, pore expansion, and high leakage rates in the later stages, seriously threatening the structural safety of underground engineering projects. Secondly, existing solid waste grouting materials mostly use calcined slag powder and inorganic cementitious materials (such as CN119143452B, CN121517148A), requiring calcination temperatures typically of 600-800℃ (energy consumption ≥300kWh / t), and the process is cumbersome, requiring crushing and grinding. Grinding, calcination, and cooling cannot simultaneously meet the requirements of high solid waste, low energy consumption, and environmental protection. Furthermore, existing technologies have not broken through the traditional framework of "inorganic cementitious material + solid waste" (such as CN121342465A and CN120923191A). Relying solely on the inherent activity of solid waste such as tunnel boring machine (TBM) slag or a single modifier cannot achieve effective cementation. The performance of grouting materials deteriorates sharply after the solid waste content exceeds 60%. There is still a lack of effective technical pathways for the large-scale and high-value utilization of bulk urban solid waste such as TBM slag and construction waste. Finally, traditional grouting materials use fixed formulas or empirical ratios, making it difficult to ensure that the performance (strength, impermeability, and fluidity) of the grout body meets the standards under different engineering conditions.

[0004] Therefore, developing an intelligent grouting material that completely eliminates inorganic cementitious materials such as cement, can efficiently absorb various solid wastes (solid waste content ≥80%), has both high impermeability and long-term water stability, and can adapt to raw material fluctuations has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] This invention provides a composite grouting material and its preparation method to solve the problems of long-term water erosion and cracking, low solid waste utilization rate, high energy consumption, limited solid waste dosage, and inability of fixed proportions to adapt to raw material fluctuations caused by the use of inorganic cementitious materials such as cement in existing grouting materials, thereby achieving low-energy consumption, green and intelligent grouting.

[0006] This invention provides a composite grouting material comprising the following components in parts by weight:

[0007] 80-92 parts of dual-source solid waste aggregate;

[0008] Nano activator 0.5-3 parts;

[0009] 5-10 parts of biomineralizing bacterial solution;

[0010] 2-5 parts organic coating agent;

[0011] 0.5-2 parts of auxiliary modifier;

[0012] The dual-source solid waste aggregate includes original soil from tunnel boring machine excavation and construction waste sand.

[0013] The nano-activator includes nano-silica sol and graphene oxide;

[0014] The biomineralizing bacterial solution includes urease-producing microorganisms and a cementing solution, wherein the cementing solution includes calcium ions.

[0015] Preferably, the original soil from the shield tunneling excavation is waste soil generated during shield tunneling construction that has been crushed and screened to a particle size ≤2mm and has not been calcined, with its moisture content controlled between 35% and 55% (when the moisture content is below 35%, water is added and stirred to the target range; when the moisture content is above 55%, it is left to drain, filtered, or naturally dried to the target range); the construction waste sand is construction waste that has been crushed and screened to a particle size ≤5mm; wherein, the mass ratio of the original soil from the shield tunneling excavation to the construction waste sand is 60~90:10~40.

[0016] Preferably, the mass ratio of the nano-silica sol to the graphene oxide is 1~5:0.02.

[0017] Preferably, the cementing solution is a mixed solution of calcium chloride and urea; the molar ratio between calcium chloride and urea is 1:1 to 1:1.6.

[0018] Preferably, the organic coating agent is an ethylene-vinyl acetate copolymer, and the solid content of the ethylene-vinyl acetate copolymer is ≥98%.

[0019] Preferably, the auxiliary modifier includes a rheology modifier, which includes a polycarboxylate superplasticizer and / or hydroxypropyl methylcellulose.

[0020] Preferably, the auxiliary modifier further includes a pH buffer.

[0021] Preferably, the components include the following parts by weight: 60 parts of original shield tunnel slag soil; 26 parts of construction waste sand; 1.98 parts of nano-silica sol; 0.02 parts of graphene oxide; 10 parts of biomineralizing bacterial solution; 2-5 parts of organic coating agent; and 0.8 parts of auxiliary modifier.

[0022] Preferably, the composite grouting material has the following characteristics: 28-day compressive strength ≥ 2.5 MPa, and / or permeability coefficient ≤ 1.0 × 10⁻⁶. -8 cm / s, and / or 180d water immersion strength loss rate ≤6%, and / or flowability 180~220mm, and / or total solid waste content ≥80%.

[0023] A method for preparing a composite grouting material includes the following steps:

[0024] The aggregate from the two sources of solid waste is crushed and screened, and the moisture content of the original soil of the shield tunnel slag is adjusted to 35% to 55%. At the same time, the key fluctuation parameters of the aggregate from the two sources of solid waste are collected in real time. The key fluctuation parameters include moisture content and / or mud content and / or organic matter content and / or plasticity index.

[0025] The key fluctuation parameters are input into the pre-trained formulation model, which outputs the optimal dosage of nano-activator, biomineralized bacterial solution, organic coating agent and auxiliary modifier, and automatically calculates and outputs the real-time ratio of each component.

[0026] Nano-activator, biomineralizing bacterial solution, organic coating agent, and auxiliary modifier are prepared separately. The organic coating agent is first added to the dual-source solid waste aggregate and dry-mixed for 5-8 minutes. Then, half of the auxiliary modifier is added to the dry material mixture and stirred for 4-6 minutes. Next, the nano-activator and biomineralizing bacterial solution are added in sequence and stirred for 6-9 minutes. Finally, the remaining auxiliary modifier is added and stirred for 12-15 minutes to form a uniform composite grouting slurry.

[0027] The present invention provides a composite grouting material and its preparation method, which, compared with the prior art, have the following superior advantages:

[0028] 1. Completely eliminates all inorganic cementing materials such as cement, steel slag, and mineral slag: By not relying on inorganic cementing materials such as cement and mineral slag, it avoids calcium dissolution of hydration products and drying shrinkage cracking. After 180 days of water immersion testing, the strength loss rate is ≤6%, significantly better than traditional cement-based grouting materials (usually ≥20%), fundamentally solving the potential for later water seepage and leakage. It constructs a four-layer composite cementing system of "nano-activation - biomineralization - organic coating - skeleton locking," replacing the cementing function of inorganic cementing materials, compensating for the low activity defects of the original slag and soil, and ensuring stable grout strength, fluidity, and impermeability even with high solid waste content.

[0029] 2. AI-powered intelligent proportioning with adaptive raw material fluctuations: An intelligent proportioning optimization AI model has been established to achieve fully automated control of the entire process, from real-time raw material detection to AI proportioning calculation and closed-loop feedback correction. It achieves dynamic balance of "high solid waste, low energy consumption, water erosion resistance, and strength" under multiple working conditions, ensuring that the performance of grouting materials meets the standards under different engineering conditions and is feasible for large-scale industrial application.

[0030] 3. High solid waste content and low energy consumption: The total content of dual-source solid waste aggregate is ≥80%, and all of them are uncalcined raw solid waste. The energy consumption for treatment is ≤50kWh / t, which is about 60%~70% lower than that of cement production. It takes into account both high solid waste resource utilization and low energy consumption, and realizes the large-scale collaborative disposal of two major types of urban solid waste: tunnel boring machine slag and construction waste.

[0031] 4. Excellent overall performance: Constructing a grouting system that is "non-inorganic cementing, original slag without calcination, and high solid waste", clarifying the four-fold synergistic cementing mechanism breaks the traditional framework of "inorganic cementing and calcination to enhance activity", providing a brand-new technical route for water erosion resistant and low-energy consumption materials for grouting projects. Attached Figure Description

[0032] 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 of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 For grouting material flow testing;

[0034] Figure 2 For testing the compressive strength of grouting materials;

[0035] Figure 3 The effect of organic coating agent dosage on the 180-day water immersion strength loss rate of grouting materials;

[0036] Figure 4 The effect of organic coating agent dosage on the 28-day unconfined compressive strength of grouting materials. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Please see Figures 1 to 4 This invention provides a composite grouting material. More specifically, this composite grouting material is a non-inorganic cementitious high-solid-waste-content green intelligent composite grouting material, completely eliminating inorganic cementitious materials such as cement, steel slag, and mineral slag. It comprises the following components in parts by weight: 80-92 parts of dual-source solid waste aggregate; 0.5-3 parts of nano-activator; 5-10 parts of bio-mineralizing bacterial solution; 2-5 parts of organic coating agent; and 0.5-2 parts of auxiliary modifier. The dual-source solid waste aggregate includes undisturbed shield tunneling excavated soil and construction waste sand. The undisturbed shield tunneling excavated soil, after being crushed and screened to a particle size ≤2mm and without calcination, is the undisturbed shield tunneling excavated soil. The construction waste, after being crushed and screened to a particle size ≤5mm, is the construction waste sand. In some feasible embodiments, the dual-source solid waste aggregate consists of undisturbed shield tunneling excavated soil and construction waste sand. The original soil from the tunnel boring machine is 60-90 parts by weight, and the construction waste sand is 10-40 parts by weight.

[0039] In any feasible embodiment, the original soil of the tunnel boring machine is taken from the waste soil generated during the construction of subway tunnel boring machines, with a moisture content of 35%~55%, a mud content of 20%~35%, and an organic matter content of 1.5%~3.0%. It is crushed by a jaw crusher and vibrated screened to a particle size of ≤2mm, without any calcination or chemical activation treatment.

[0040] In any feasible embodiment, the construction waste sand is taken from a construction waste disposal site and mainly consists of waste concrete and red bricks, which are crushed and screened to a particle size of ≤5mm.

[0041] In one specific embodiment of the present invention, the nano-activator includes nano-silica sol and / or graphene oxide. The nano-activator is used to provide active sites and micro / nano-filling.

[0042] In some feasible embodiments, the nano-activator is composed of nano-silica sol and graphene oxide, wherein the mass ratio of nano-silica sol to graphene oxide is 1~5:0.02.

[0043] In any feasible embodiment, the nano-activator is composed of nano-silica sol and graphene oxide, wherein the mass ratio of nano-silica sol to graphene oxide is 3:0.02.

[0044] In one specific embodiment of the present invention, the biomineralizing bacterial solution includes urease-producing microorganisms and / or a cementing solution. The biomineralizing bacterial solution is used to induce calcium carbonate precipitation to achieve particle cementation. The urease-producing microorganism is *Bacillus pasteurellii*. *Bacillus pasteurellii* possesses highly active urease, which can rapidly hydrolyze urea to generate carbonate ions. In the presence of a calcium source (such as calcium chloride), it can efficiently generate calcium carbonate precipitate, thus playing a cementing role. The concentration of the urease-producing microorganism solution is 10. 7 ~10 9 CFU / mL; the cementing solution is a calcium chloride-urea mixed solution with a molar ratio of calcium chloride to urea of ​​1:1 to 1:1.6.

[0045] In some feasible embodiments, the biomineralizing bacterial solution comprises urease-producing microorganisms and a cementing solution, wherein the urease-producing microorganisms are Bacillus pasteurellii, and the bacterial solution concentration is 10. 7 ~10 9 CFU / mL; the cementing solution is a calcium chloride-urea mixed solution with a molar ratio of calcium chloride to urea of ​​1:1 to 1:1.6.

[0046] In one specific embodiment of the present invention, the organic coating agent is an ethylene-vinyl acetate copolymer with a solid content ≥98%, exhibiting outstanding bonding strength, significantly improving material flexibility, water resistance, and durability, and enhancing crack resistance and adhesion. The preparation process of the organic coating agent with a solid content ≥98% involves spray drying EVA emulsion into redispersible latex powder. The organic coating agent is used to form a hydrophobic film layer and microenvironment barrier, which, combined with aggregate gradation and skeleton locking, significantly improves impermeability and long-term water stability.

[0047] As a specific embodiment of the present invention, the auxiliary modifier includes a rheology modifier and / or a pH buffer; wherein the rheology modifier includes a polycarboxylate superplasticizer and / or hydroxypropyl methylcellulose, and the pH buffer is sodium bicarbonate.

[0048] In some feasible embodiments, the auxiliary modifiers include rheology modifiers and / or pH buffers; wherein the rheology modifiers include polycarboxylate superplasticizers and hydroxypropyl methylcellulose, and the pH buffer is sodium bicarbonate.

[0049] In any feasible embodiment, the auxiliary modifier includes a rheology modifier and a pH buffer, wherein the rheology modifier is selected from polycarboxylate superplasticizers and hydroxypropyl methylcellulose, and the pH buffer is sodium bicarbonate.

[0050] The composite grouting material provided by this invention has the following characteristics: 28-day compressive strength ≥ 2.5 MPa, and / or permeability coefficient ≤ 1.0 × 10⁻⁶. -8cm / s, and / or 180d water immersion strength loss rate ≤6%, and / or flowability 180~220mm, and / or total solid waste content ≥80%.

[0051] In any feasible embodiment, the composite grouting material has the following characteristics: 28-day compressive strength ≥ 2.5 MPa; permeability coefficient ≤ 1.0 × 10⁻⁶. -8 cm / s; 180d water immersion strength loss rate ≤6%; flowability 180~220mm; total solid waste content ≥80%.

[0052] The synergistic mechanism between the non-inorganic cementitious composite cementing system and the undisturbed slag soil of this invention is as follows: The grouting material forms a composite cementing structure through a four-fold synergistic mechanism of "nano-activation - biomineralization - organic coating - skeleton locking," achieving water erosion resistance, crack resistance, and seepage prevention. Specifically, the nano-phase activation and network construction mechanism: Nano-silica sol has highly active silanol groups (-Si-OH), which form hydrogen bonds with the hydroxyl groups (-OH) on the surface of the undisturbed slag soil, while simultaneously activating the potential active components (SiO2, Al2O3) in the slag soil to undergo a pozzolanic reaction (reaction formula: SiO2 (slag soil) + Al2O3 (slag soil) + Ca). 2+ (Cementing solution) + H2O → CASH gel), generating amorphous CASH gel products, replacing the cementing effect of traditional CSH gels; graphene oxide, through its surface oxygen-containing functional groups (hydroxyl, carboxyl groups), forms a "π-π stacking + hydrogen bonding" interaction with silica sol and undisturbed slag particles, constructing a continuous three-dimensional nano-network framework, "locking" dispersed solid waste particles into a whole, inhibiting particle loosening and microcrack propagation, and enhancing interfacial adhesion. Biomineralization dense cementing mechanism: urease catalyzes the hydrolysis of urea in the cementing solution (reaction formula: CO(NH2)2 + 2H2O → urease → 2NH3・H2O + CO2 → 2NH4). + + CO3 2- This raises the pH of the slurry to 9.5-10.5, creating an alkaline mineralization environment and accelerating the active reaction between silica sol and the undisturbed slag; carbonate ions (CO3) 2- ) and calcium ions (Ca) in the cementing solution 2+ ) combine to form calcium carbonate crystals (reaction formula: Ca 2+ + CO3 2-→ CaCO3↓), with crystal structure mainly composed of calcite (high strength) + aragonite (high density), filled in three levels: macroscopic level (5~20μm): filling large pores between original slag particles; microscopic level (1~5μm): filling the gaps in the nano-network; nanoscale level (50~500nm): filling the micropores inside the CASH gel; calcium carbonate crystals and CASH gel form an "interpenetrating structure", making the total porosity of the slurry ≤12%, replacing inorganic cementing materials to achieve high strength and high density. Organic coating anti-water erosion mechanism: The organic coating agent forms a hydrophobic organic film layer on the surface of the pores and between particles inside the mineralized material, reducing the water penetration path, and at the same time, it acts as a flexible buffer layer to absorb deformation energy and inhibit the propagation of microcracks; at the same time, this organic film layer provides physical isolation for microorganisms, resisting the erosion of high water pressure and high salt and high alkaline environments, ensuring the long-term mineralization activity of biomineralization. The four-fold synergistic locking mechanism provides "skeleton support", biomineralization products provide "dense filling", organic membranes provide "water-resistant protection", and undisturbed soil particles provide "strength skeleton". The four work together to form a stable "non-inorganic cementing" system, achieving high solid waste, high strength, high impermeability, and high durability.

[0053] The present invention provides a method for preparing a composite grouting material, comprising the following steps:

[0054] Step S1: Raw material pretreatment and real-time monitoring

[0055] The original soil of the shield tunneling excavation and the sand of construction waste are crushed and screened respectively, and the moisture content of the original soil of the shield tunneling excavation is adjusted to 35% to 55%. At the same time, the key fluctuation parameters of the dual-source solid waste aggregate are collected in real time by online sensors. The key fluctuation parameters include moisture content and / or mud content and / or organic matter content and / or plasticity index.

[0056] In this step, the original soil of the tunnel boring machine is crushed and passed through a 2mm sieve. When the moisture content is less than 35%, water is added and stirred to the target range. When the moisture content is higher than 55%, it is left to stand to drain, filter by pressure, or air dry to the target range. The construction waste sand is crushed and passed through a 5mm sieve.

[0057] Step S2: AI Intelligent Proportion Optimization

[0058] The key fluctuation parameters collected in step S1 are input into the pre-trained artificial intelligence ratio optimization model. The model outputs the optimal dosage of nano-activator, biomineralized bacterial solution, organic coating agent and auxiliary modifier. The embedded control system automatically calculates and outputs the real-time ratio of each component.

[0059] In this step, the artificial intelligence proportioning optimization model is constructed based on a deep neural network or a hybrid neural network of genetic algorithm-backpropagation. The training dataset comes from historical experimental data and field working condition data. The input layer consists of key fluctuation parameters of solid waste aggregate, and the output layer consists of the optimal dosage of nano-activator, biomineralizing bacterial solution, organic coating agent, and auxiliary modifier. Constraints include 28-day compressive strength ≥ 2.5 MPa and permeability coefficient ≤ 1.0 × 10⁻⁴ MPa. 8 cm / s, flowability 180~220mm.

[0060] Step 3: Hierarchical mixing and synergistic reaction control

[0061] Graphene oxide was dispersed in silica sol and ultrasonically treated for 30-40 minutes to prepare a nano-activator.

[0062] Dissolve urease in the cementing solution and stir at a constant temperature of 20-30℃ for 12-18 minutes to prepare a biomineralizing bacterial solution.

[0063] The rheology modifier and pH buffer were dissolved in water and stirred evenly to form an auxiliary modifier;

[0064] First, add the organic coating agent to the dual-source solid waste aggregate and dry mix for 5-8 minutes. Then, add half of the auxiliary modifier to the dry material mixture and stir for 4-6 minutes. Next, add the nano activator and biomineralizing bacterial solution in sequence and stir for 6-9 minutes. Finally, add the remaining auxiliary modifier and continue stirring for 12-15 minutes to form a uniform composite grouting slurry.

[0065] In this step, the slurry state is monitored in real time using an online viscometer and pH meter. When the monitored value deviates from the set threshold, it is fed back to the AI ​​model for minor correction of the mixing ratio to ensure stable performance.

[0066] The performance tests of this invention are based on the following: fluidity is determined according to the "Method for Determination of Flowability of Cement Mortar" (GB / T2419-2005); unconfined compressive strength, impermeability, and immersion strength loss rate are determined according to the "Standard for Test Methods of Basic Performance of Building Mortar" (IGJ / T70-2009).

[0067] Example 1

[0068] A composite grouting material comprises the following components in parts by weight: 90 parts of dual-source solid waste aggregate; 1.2 parts of nano-activator; 8 parts of biomineralizing bacterial solution; 3 parts of organic coating agent; and 0.8 parts of auxiliary modifier.

[0069] The present invention provides a method for preparing a composite grouting material, comprising the following steps:

[0070] Step 1: Take undisturbed soil from a tunnel section and construction waste sand, crush and screen them separately. Real-time online sensor monitoring shows: moisture content 35.5%, mud content 22.3%, organic matter content 1.8%, and plasticity index 17. The moisture content of the construction waste sand is 3.2%.

[0071] Step 2: Input the above parameters and 90% of the dual-source solid waste aggregate (65% shield tunnel slag and original soil, 25% construction waste sand) into the trained model. The model outputs the optimal mix ratio (mass percentage) as follows: 1.18% silica sol, 0.02% graphene oxide, 8% biomineralization bacterial solution (including cementing solution), 3% ethylene-vinyl acetate copolymer, 0.3% polycarboxylate superplasticizer, and 0.5% sodium bicarbonate.

[0072] Step 3: Add the tunnel boring machine slag, construction waste sand, and ethylene-vinyl acetate copolymer to a forced mixer and dry mix for 5 minutes; add half the volume of auxiliary modifier mother liquor (polycarboxylate superplasticizer + sodium bicarbonate) (0.4% dosage corresponding to volume) to the dry mixture, stir for 5 minutes to initially wet the slurry and adjust the pH value to 7.9; add the nano activator (silica sol + graphene oxide) and biomineralizing bacterial solution in sequence, stir for 8 minutes at 80 rpm to fully disperse the nanoparticles and urease and allow them to undergo an initial reaction; add the remaining auxiliary modifier mother liquor (polycarboxylate superplasticizer + sodium bicarbonate) (0.4% dosage corresponding to volume), and continue stirring for 13 minutes at 60 rpm to form a uniform composite grouting slurry.

[0073] The grouting material prepared in this embodiment was subjected to performance tests, yielding a flowability of 190 mm, a 28-day unconfined compressive strength of 2.9 MPa, and a permeability coefficient of 9.2 × 10⁻⁶. -9 cm / s, 180d water immersion strength loss rate 4.7%.

[0074] Example 2

[0075] A composite grouting material comprises the following components in parts by weight: 86 parts of dual-source solid waste aggregate; 2 parts of nano-activator; 10 parts of biomineralizing bacterial solution; 4.5 parts of organic coating agent; and 0.8 parts of auxiliary modifier.

[0076] The mixture is basically the same as in Example 1, except that the content of the dual-source solid waste aggregate is 86% (60% shield tunnel slag and original soil, 26% construction waste sand). The AI ​​model output parameters automatically adjust the ratio to: 1.98% silica sol, 0.02% graphene oxide, 10% biomineralization bacterial solution (including cementing solution), 4.5% ethylene-vinyl acetate copolymer, 0.4% polycarboxylate superplasticizer, and 0.4% sodium bicarbonate.

[0077] The grouting material prepared in this embodiment was subjected to performance tests, yielding a flowability of 200 mm, a 28-day unconfined compressive strength of 3.4 MPa, and a permeability coefficient of 8.7 × 10⁻⁶. -9 cm / s, 180d water immersion strength loss rate 4.1%.

[0078] Example 3

[0079] A composite grouting material comprises the following components in parts by weight: 85 parts of dual-source solid waste aggregate; 2.2 parts of nano-activator; 9 parts of biomineralized bacterial solution; 4 parts of organic coating agent; and 1 part of auxiliary modifier.

[0080] The mixture is basically the same as in Example 1, except that the original soil of the tunnel boring machine (TBM) slag has a high moisture content of 52.3%, a mud content of 31.2%, an organic matter content of 2.5%, a plasticity index of 20, and a dual-source solid waste aggregate content of 85% (60% original TBM slag soil and 25% construction waste sand). The AI ​​model output parameters automatically adjust the proportions to: 2.18% silica sol, 0.02% graphene oxide, 9% biomineralization bacterial solution (including cementing solution), 4% ethylene-vinyl acetate copolymer, 0.6% polycarboxylate superplasticizer, and 0.4% sodium bicarbonate.

[0081] The grouting material prepared in this embodiment was subjected to performance tests, yielding a flowability of 220 mm, a 28-day unconfined compressive strength of 3.2 MPa, and a permeability coefficient of 9.5 × 10⁻⁶. -9 cm / s, 180d water immersion strength loss rate 4.9%.

[0082] Comparative Example

[0083] Same as Example 2, but with the addition of different amounts of organic coating agent; the remaining steps remain unchanged. The test results are shown in Table 1.

[0084] Organic coating agent dosage % Flowability / mm 28-day unconfined compressive strength / MPa <![CDATA[Permeability coefficient / 1×10 -9 cm / s]]> 180-day water immersion strength loss rate / % 0 195 2.3 10.4 6.3 2 191 2.5 9.7 5.2 3 195 2.9 9.2 4.7 4 193 3.4 8.2 4.1 5 200 3.7 7.5 3.3 6 195 3.0 6.4 2.7

[0085] The test results show that the strength continuously increases with increasing admixture dosage, from 2.3 MPa to 3.7 MPa (an increase of 60.9%). However, when the admixture dosage exceeds 5%, the strength drops to 3.0 MPa (a decrease of 18.9%). This indicates that excessive organic coating agent coats the aggregate surface, hindering the direct bonding between inorganic binders (calcium carbonate precipitation) and the aggregate, forming a "lubricating layer" that actually weakens the strength. The permeability coefficient decreases monotonically with increasing admixture dosage, from 10.4 × 10⁻⁻⁻⁶. 8 cm / s decreased to 6.4×10⁻ 8The decrease in flow rate (cm / s) by 36% indicates that the organic film layer continuously enhances the filling and hydrophobic effects on pores, resulting in improved impermeability. The loss rate monotonically decreases with increasing dosage, from 6.3% to 2.7% (a reduction of 53.4%), indicating that the hydrophobic film layer formed by the organic coating agent effectively protects the cemented structure, reduces water erosion and microbial loss, and significantly improves long-term water stability. The fluidity remains relatively stable at 190–193 mm, with minimal fluctuation (<2%), indicating that the organic coating agent dosage within the range of 0%–6% has negligible impact on the grout workability, meeting the grouting construction requirements of 180–220 mm.

[0086] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention. The material preparation process involves no calcination step, and the 28-day compressive strength is ≥2.5 MPa, with a permeability coefficient ≤1.0 × 10⁻⁻⁻⁶. 8 With a strength loss rate of ≤6% after 180 days of water immersion, it combines high solid waste resource utilization, low carbon and environmental protection, and adaptability to harsh working conditions. It is suitable for tunnel seepage prevention, slope reinforcement, underground foundation treatment and other projects, and has broad prospects for industrial application.

[0087] The above provides a detailed description of the composite grouting material and its preparation method provided by the present invention. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A composite grouting material, characterized in that, The components include the following parts by mass: 80-92 parts of dual-source solid waste aggregate; Nano-activator 0.5-3 parts; 5-10 parts of biomineralizing bacterial solution; 2-5 parts organic coating agent; 0.5-2 parts of auxiliary modifier; The dual-source solid waste aggregate includes original soil from tunnel boring machine excavation and construction waste sand. The nano-activator includes nano-silica sol and graphene oxide; The biomineralizing bacterial solution includes urease-producing microorganisms and a cementing solution, wherein the cementing solution includes calcium ions.

2. The composite grouting material according to claim 1, characterized in that, The original soil from the shield tunneling excavation is waste soil generated during shield tunneling construction, which is crushed and screened to a particle size ≤2mm and has not been calcined. Its moisture content is controlled between 35% and 55% (when the moisture content is less than 35%, water is added and stirred to the target range; when the moisture content is higher than 55%, it is left to drain, filter, or air-dry to the target range). The construction waste sand is construction waste that is crushed and screened to a particle size ≤5mm. The mass ratio of the original soil from the shield tunneling excavation to the construction waste sand is 60~90:10~40.

3. The composite grouting material according to claim 2, characterized in that, The mass ratio of the nano-silica sol to the graphene oxide is 1~5:0.

02.

4. The composite grouting material according to claim 3, characterized in that, The cementing solution is a mixed solution of calcium chloride and urea; the molar ratio between calcium chloride and urea is 1:1 to 1:1.

6.

5. The composite grouting material according to claim 4, characterized in that, The organic coating agent is an ethylene-vinyl acetate copolymer, and the solid content of the ethylene-vinyl acetate copolymer is ≥98%.

6. The composite grouting material according to claim 5, characterized in that, The auxiliary modifier includes a rheology modifier, which includes a polycarboxylate superplasticizer and / or hydroxypropyl methylcellulose.

7. The composite grouting material according to claim 6, characterized in that, The auxiliary modifier also includes: pH buffer.

8. The composite grouting material according to claim 7, characterized in that, The components include the following parts by weight: 60 parts of original soil from tunnel boring machine excavation; 26 parts of construction waste sand; 1.98 parts of nano-silica sol; 0.02 parts of graphene oxide; 10 parts of biomineralizing bacterial solution; and 2-5 parts of organic coating agent. 0.8 parts of auxiliary modifier.

9. The composite grouting material according to any one of claims 1-8, characterized in that, The composite grouting material has the following characteristics: 28-day compressive strength ≥ 2.5 MPa, and / or permeability coefficient ≤ 1.0 × 10⁻⁶. -8 cm / s, and / or 180d water immersion strength loss rate ≤6%, and / or flowability 180~220mm, and / or total solid waste content ≥80%.

10. A method for preparing a composite grouting material, characterized in that, Includes the following steps: The aggregate from the dual-source solid waste is crushed and screened, and the moisture content of the shield tunnel slag is adjusted to 35% to 55%. At the same time, the key fluctuation parameters of the aggregate from the dual-source solid waste are collected in real time. The key fluctuation parameters include moisture content and / or mud content and / or organic matter content and / or plasticity index. The key fluctuation parameters are input into the pre-trained formulation model, which outputs the optimal dosage of nano-activator, biomineralized bacterial solution, organic coating agent and auxiliary modifier, and automatically calculates and outputs the real-time ratio of each component. Nano-activator, biomineralizing bacterial solution, organic coating agent, and auxiliary modifier are prepared separately. The organic coating agent is first added to the dual-source solid waste aggregate and dry-mixed for 5-8 minutes. Then, half of the auxiliary modifier is added to the dry material mixture and stirred for 4-6 minutes. Next, the nano-activator and biomineralizing bacterial solution are added in sequence and stirred for 6-9 minutes. Finally, the remaining auxiliary modifier is added and stirred for 12-15 minutes to form a uniform composite grouting slurry.

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