A high-performance environmentally friendly synchronous grouting material and its preparation method

Abstract

The invention relates to a high-performance environment-friendly synchronous grouting material and a preparation method thereof. The raw materials of the synchronous grouting material include, by weight, 10-15 parts of cement, 15-20 parts of slag, 20-30 parts of steel slag, 300-320 parts of mud-containing powdered fine sand, 0.075-0.1 parts of iron sulfide, 0.05-0.12 parts of graphene oxide, 0.03-0.09 parts of N,N-diisopropylformamide and 45-50 parts of water. The invention uses the mud-containing powdered fine sand as a raw material to replace bentonite and fine sand in the original synchronous grouting material, and mixes cement, slag, iron sulfide, graphene oxide and other materials. The components act synergistically, so that the prepared synchronous grouting material has excellent impermeability and compressive strength, short setting time, low carbon and environmental protection, and high economic and social benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of synchronous grouting, and more specifically, to a high-performance environmentally friendly synchronous grouting material and a preparation method thereof. Background Art

[0002] Synchronous grouting technology is an essential key auxiliary method in the shield tunneling method. Synchronous grouting during shield tunneling is an effective means to fill the building gap between the segment lining and the stratum and reduce the subsequent soil deformation, which can enhance the stability of the tunnel and is the key to controlling surface settlement.

[0003] Synchronous grouting slurry is generally cement mortar, which is prepared by mixing cement, sand, fly ash, bentonite, and water in a certain proportion. However, the output of shield muck in urban subway construction is extremely abundant. If these resources can be effectively utilized to prepare synchronous grouting materials, it will bring huge economic, environmental, and social benefits.

[0004] At present, there are a series of problems in the technology of preparing synchronous grouting materials from muck at home and abroad: First, the original muck obtained from shield excavation is generally used as the raw material. The original muck has a poor grading and many coarse particles, and there are problems of layering precipitation or pipe blockage during the transportation of the prepared slurry. During grouting, it may lead to incomplete filling behind the segment wall. At the same time, the consumption of cementitious materials such as cement is still large, and the economy and environmental protection are poor. Second, the setting time of the slurry is long (generally exceeding 15 hours), and the slurry remains in a fluid state for a long time, making the buoyancy force on the segment greater than its own gravity, resulting in segment floating. Third, the anti-seepage ability of the slurry is poor, and the segment leaks seriously. It is difficult to control the quality, and the construction safety risk is high. Fourth, the shield muck in coastal areas and undersea tunnels contains a large amount of chloride ions and sulfate ions. Chloride ions will accelerate the corrosion of steel bars, leading to concrete cracking; sulfate ions will erode the tunnel lining concrete and reduce its structural bearing capacity.

[0005] Therefore, it is of great significance to develop a synchronous grouting material with strong anti-seepage ability, controllable setting time and strength, and economic and environmental protection. Summary of the Invention

[0006] In view of the above technical problems, the present invention innovatively uses silt-containing fine sand as the raw material to replace bentonite and fine sand in the original synchronous grouting material, and compound materials such as cement, slag, iron sulfide, and graphene oxide. The components act synergistically to make the prepared synchronous grouting material have excellent anti-seepage performance and compressive strength, and short setting time, low carbon and environmental protection, with high economic and social benefits.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows:

[0008] A high-performance environmentally friendly synchronous grouting material, by weight, comprises the following components:

[0009] 10 - 15 parts of cement

[0010] 15 - 20 parts of slag

[0011] 20 - 30 parts of steel slag

[0012] 300 - 320 parts of silt - containing fine sand

[0013] 0.075 - 0.1 part of iron sulfide

[0014] 0.05 - 0.12 part of graphene oxide

[0015] 0.03 - 0.09 part of N, N - diisopropylformamide

[0016] 45 - 50 parts of water.

[0017] In some embodiments, the cement is ordinary Portland cement and / or sulfoaluminate cement; specifically, the ordinary Portland cement includes PO52.5 cement, PO42.5 cement, PO52.5R cement, and PO42.5R cement.

[0018] In some embodiments, the density of the slag is 2.5 - 3.0 g / cm 3 , and the specific surface area is 370 - 480 m 2 / kg.

[0019] In some embodiments, the fineness of the steel slag is 200 - 300 mesh, the density is 3.0 - 3.5 g / cm 3 , and the 28 - day activity value is 95% - 96%.

[0020] In some embodiments, the particle size of the silt - containing fine sand is ≤20 μm, and the clay content is 15 - 25%.

[0021] In some embodiments, the silt - containing fine sand is obtained by multi - stage screening of shield muck.

[0022] In some embodiments, the method for screening shield muck to obtain silt - containing fine sand includes the following steps:

[0023] (1) The slurry of slurry - balanced shield is transported from the tunnel to the vibrating screen of the water treatment equipment, and the sand - containing slurry with a particle size of 3 - 6 mm is separated;

[0024] (2) The sand - containing slurry obtained in step (1) enters the first - stage hydrocyclone to separate the sand - containing slurry with a particle size below 74 μm;

[0025] (3) The sand - containing slurry with a particle size below 74 μm enters the second - stage hydrocyclone to separate the silt - containing fine sand with a particle size below 20 μm.

[0026] The present invention also provides a preparation method for the shield muck in any of the above embodiments, and the method includes the following steps:

[0027] S1. Mix cement, slag, silt-containing fine sand, and part of water evenly to obtain a first slurry;

[0028] S2. Add steel slag and iron sulfide into the first slurry, and then add part of water and mix evenly to obtain a second slurry;

[0029] S3. Add graphene oxide into part of water, mix evenly, and then add it into the second slurry to obtain a third slurry;

[0030] S4. Add N,N-diisopropylformamide into the remaining water, mix evenly, and then add it into the third slurry to obtain the high-performance environmentally friendly synchronous grouting material.

[0031] In some embodiments, in step S1, the stirring time is 1 - 3 min.

[0032] In some embodiments, in step S2, the stirring time is 0.5 - 2 min.

[0033] In some embodiments, in step S3, the stirring time is 1 - 3 min.

[0034] In some embodiments, in step S4, the stirring time is 1 - 3 min.

[0035] In some embodiments, the total stirring time in steps S1 to S4 is controlled within 6 - 8 min.

[0036] In the technical solution of the present invention, the principle of the interaction between each component is as follows:

[0037] 1. The particle size distribution and particle gradation of the silt-containing fine sand are respectively as Figure 1 and Figure 2 shown. The silt-containing fine sand contains a large amount of chloride ions and sulfate ions, which can interact with other components. The combined action of iron sulfide, fine sand, and steel slag solidifies the chloride ions in the silt-containing fine sand and activates the activity of steel slag;

[0038] A large amount of calcium hydroxide is generated during the hydration of cement:

[0039] 2(3CaO·SiO2) + 6H2O = 3CaO·SiO2·3H2O + 3Ca(OH)2

[0040] 2(2CaO·SiO2) + 4H2O = 3CaO·SiO2·3H2O + Ca(OH)2

[0041] 3CaO·Al2O3 + 6H2O = 3CaO·Al2O 3· 6H2O

[0042] 3CaO·Al2O3·6H2O + 3(Ca2SO4·2H2O) + 19H2O = 3CaO·Al2O3·3Ca2SO4·31H2O

[0043] 4CaO·Al2O3·Fe2O3 + 7H2O = 3CaO·Al2O3·6H2O + CaO·Fe2O3·H2O;

[0044] Iron sulfide (Fe2S3) reacts with calcium hydroxide produced by cement hydration and chloride ions in the silt-containing fine sand to obtain calcium sulfide, iron hydroxide, and calcium chloride;

[0045] The main mineral components of steel slag are tricalcium silicate, dicalcium silicate, calcium magnesium olivine, calcium magnesium rhodonite, dicalcium ferrite, RO (solid solution formed by oxides of magnesium, iron, and manganese, i.e., FeO, MgO, MnO), free calcium oxide (f-CaO), etc. Among them, the active minerals such as tricalcium silicate (C3S), dicalcium silicate (C2S), and ferroaluminate have certain hydraulic cementitious properties, and their hydration reactions are similar to those of cement clinker minerals.

[0046] At the same time, the free calcium oxide contained in the steel slag reacts with water to form calcium hydroxide, and further reacts with sulfate ions in the silt-containing fine sand to form expansive hydration products such as gypsum and ettringite. While solidifying the sulfate ions in the fine sand, it can also densify the microstructure of the hardened body and improve its strength. The chemical reaction equations are as follows:

[0047] CaO + H2O = Ca(OH)2

[0048] Ca(OH)2 + SO4 2- = CaSO4

[0049] CaSO4 + 2H2O = CaSO4·2H2O

[0050] 3CaO·Al2O3·6H2O + 3(Ca2SO4·2H2O) + 19H2O = 3CaO·Al2O3·3Ca2SO4·31H2O

[0051] 2. N,N-Diisopropylformamide undergoes a complexation reaction with iron sulfide and calcium chloride to solidify the chloride ions in the silt-containing fine sand, promote the nucleation effect of graphene oxide, and at the same time undergoes a chelation reaction with Fe in the steel slag and iron sulfide, improving the compactness and impermeability of the slurry, and avoiding the risk of steel bar corrosion at the same time, specifically as follows: 3+ Occurs a chelation reaction, improves the slurry density and impermeability performance, and at the same time avoids the risk of steel bar corrosion, specifically as follows:

[0052] Under strong alkaline conditions, N,N - diisopropylformamide undergoes hydrolysis reaction, and the amide bond (C=O) in the N,N - diisopropylformamide molecule is broken by water molecules to form carboxylic acid products; under strong alkaline conditions, the carboxylic acid products undergo complexation reactions with ferrous sulfide and calcium chloride, playing the role of sulfur fixation and chlorine fixation simultaneously. The hydrolysis group of N,N - diisopropylformamide undergoes chelation reactions with iron ions in steel slag and iron sulfide to form a network - shaped Fe - diisopropylformamide chelate, improving the density and strength of the slurry. At the same time, the hydrolysis group can also undergo chelation reactions with calcium ferroaluminate hydrate produced by the hydration of C4AF in cement clinker, promoting the early reaction rate of the slurry and increasing the early strength of the hardened slurry.

[0053] 3. Graphene oxide GO, as a nucleating agent, promotes the hydration reaction rate and hydration degree of C3S and C2S in steel slag, improving the strength of the slurry. The nucleation effect of graphene oxide promotes the hydration of C3S and C2S in steel slag, and its principle is as Figure 3 shown. Specifically: The abundant functional groups grafted on the surface of GO have nucleation effect and template effect. GO forms a GO film on the surface of C3S and C2S in steel slag through electrostatic adsorption; the GO film strongly adsorbs Ca 2+ from the pore fluid onto the channels between GO nanosheets, greatly reducing the saturation of hydration products, promoting the growth of more C - S - H on the surface of C3S, making the slurry structure denser, and improving strength and impermeability; GO nanosheets have strong water adsorption. In the early stage of hydration, they adsorb a large number of water molecules and "release" some water molecules during the diffusion - controlled period to diffuse into the interior and react with C3S to form a more dense C - S - H structure, increasing the content of high - density C - S - H, making the microstructure denser, refining the pore size, and improving the strength and impermeability of the hardened slurry.

[0054] Through experiments, the hydration effects of different amounts of graphene oxide added on C3S and C2S in steel slag are as Figure 4 shown.

[0055] In summary, through the synergistic effect among the components in the present invention, the obtained synchronous grouting material can have excellent compressive strength and impermeability.

[0056] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0057] (1) The mud-containing fine sand of the present invention has a good gradation and a dosage of more than 70%. Compared with traditional synchronous grouting materials, it achieves zero addition of fly ash, bentonite and fine sand, and can reduce cement consumption by 60%. The original slurry material cost of the project department is 268.67 yuan / cubic meter, and the slurry material cost of the present invention is about 60.48 yuan / cubic meter, which reduces the material cost by about 77.5%. At the same time, it also reduces the transportation and disposal costs of a large amount of slag, increases the added value of slag utilization, and has significant overall economic benefits.

[0058] (2) The new green admixture greatly improves the anti-seepage performance of the slurry through the synergistic effect with other components, reduces the setting time of the slurry, and improves the compressive strength of the slurry. The various properties of the slurry can be flexibly adjusted according to the on-site construction conditions and design requirements, and it has strong adaptability.

[0059] (3) The shield slag slurry making process adopted by the present invention is simple, has high production efficiency, and occupies a small area of ​​equipment, and can be adapted to small urban subway construction sites.

[0060] (4) The present invention is a green and environmentally friendly grouting material that can turn slag into treasure, reduce environmental pollution caused by slag transportation and discharge, reduce natural sand and gravel mining, and reduce secondary pollution and carbon emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 The particle size distribution diagram of the shield slag used in the embodiments and comparative examples of the present invention;

[0062] Figure 2 XRD phase analysis diagram of mud-containing fine sand used in the embodiments and comparative examples of the present invention;

[0063] Figure 3 Schematic diagram of the graphene oxide promoting hydration of steel slag;

[0064] Figure 4 The electron microscope images of different graphene oxide GO addition amounts (GO mass / steel slag mass) promoting hydration of steel slag; Figure A shows the hydration of steel slag without GO doping; Figure B shows the hydration of steel slag with 0.01% GO doping; Figure C shows the hydration of steel slag with 0.02% GO doping; Figure D shows the hydration of steel slag with 0.03% GO doping;

[0065] Figure 5 The fluidity test diagrams of Example 3 and Comparative Example 1 are shown in Figure A, wherein Figure A is the test diagram of Example 3, and Figure B is the test diagram of Comparative Example 1;

[0066] Figure 6 The figures are the coagulation time test figures of Example 3 and Comparative Example 3; wherein, Figure A is the test figure of Example 3, and Figure B is the test figure of Comparative Example 3;

[0067] Figure 7Compressive strength test diagrams for Example 3, Comparative Example 2, and Comparative Example 4; among them, Diagram A is the test diagram for Example 3, Diagram B is the test diagram for Comparative Example 2, and Diagram C is the test diagram for Comparative Example 4. Detailed implementation manners

[0068] In the following description, many specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific implementations disclosed below.

[0069] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0070] The parameters or preparation methods of some raw materials used in the examples and comparative examples of the present invention are specifically as follows:

[0071] Cement: Purchased commercially, it is PO42.5 ordinary Portland cement;

[0072] Slag: Purchased commercially, with a density of 2.89 g / cm 3 , and a specific surface area of 422.3 m 2 / kg;

[0073] Steel slag: Purchased commercially, the fineness of the steel slag is 200 - 300 meshes, the density is 3.0 - 3.5 g / cm 3 , and the 28-day activity value is 95% - 96%;

[0074] The silt-containing fine sand is obtained by multi-stage screening of shield muck, specifically as follows:

[0075] (1) The slurry of the slurry balance shield is transported from the tunnel to the vibrating screen in the slurry treatment equipment, and the sand-containing slurry of 3 - 6 mm is separated.

[0076] (2) Next, the sand-containing slurry of 3 - 6 mm enters the first-stage cyclone to separate the sand-containing slurry with a particle size below 74 μm.

[0077] (3) The sand-containing slurry continues to enter the second-stage cyclone to separate the silt-containing fine sand with a particle size below 20 μm.

[0078] Iron sulfide, graphene oxide, and N,N-diisopropylformamide are all purchased commercially.

[0079] Example 1

[0080] A high-performance environmentally friendly synchronous grouting material, by weight, comprises the following components:

[0081] 10 parts of cement

[0082] 15 parts of slag

[0083] 25 parts of steel slag

[0084] 300 parts of silt-containing fine sand

[0085] 0.075 part of iron sulfide

[0086] 0.05 part of graphene oxide

[0087] 0.03 part of N,N-diisopropylformamide

[0088] 50 parts of water;

[0089] Its preparation method includes the following steps:

[0090] (1) Use an excavator or forklift to transport the silt-containing fine sand to a mortar mixer, and transport cement and slag to the mixer through storage tanks respectively. Add water (20 parts) and fully stir with the silt-containing fine sand for 2 minutes (both are equipped with an automatic weighing system) to obtain the first slurry;

[0091] (2) Add steel slag and iron sulfide to the first slurry in sequence, then add water (15 parts) and fully stir for 1 minute to obtain the second slurry;

[0092] (3) Mix graphene oxide with water (10 parts), and then add it to the above second slurry and fully stir for 2 minutes to obtain the third slurry.

[0093] (4) Mix N-N-diisopropylformamide with water (5 parts), and then add it to the above third slurry and fully stir for 2 minutes to obtain the synchronous grouting material;

[0094] The total time for the pulp making process should be controlled within 6 - 8 minutes.

[0095] Examples 2 - 3

[0096] The composition of the synchronous grouting material in Examples 2 - 3 is shown in Table 1, and the preparation method is the same as that in Example 1.

[0097] Comparative Example 1

[0098] A synchronous grouting material, by weight, includes the following components:

[0099] 15 parts of cement

[0100] 20 parts of slag

[0101] 20 parts of steel slag

[0102] 320 parts of silt-containing fine sand

[0103] Accelerator 0.25 parts

[0104] Water 45 parts

[0105] Its preparation method comprises the following steps:

[0106] (1) Use an excavator or a forklift to transport the muddy fine sand to the mortar mixer, and the cement and slag are respectively transported to the mixer through storage tanks. Add water (20 parts) and fully stir the muddy fine sand for 2 minutes (both are equipped with an automatic weighing system) to obtain the first slurry;

[0107] (2) Add steel slag to the first slurry, and then add water (15 parts) and fully stir for 2 - 3 minutes to obtain the second slurry;

[0108] (3) After mixing the accelerator with water (10 parts), add it to the above - mentioned second slurry and fully stir for 2 - 3 minutes to obtain the third slurry, that is, the synchronous grouting material is obtained;

[0109] The total time for the pulp - making process should be controlled within 6 - 8 minutes.

[0110] Comparative Examples 2 - 4

[0111] The raw material compositions of Comparative Examples 2 - 4 are shown in Table 1, and the preparation method is the same as that of Comparative Example 1.

[0112] Table 1 Raw material ratios of examples and comparative examples

[0113]

[0114] Carry out relevant performance tests on the synchronous grouting materials obtained in Examples 1 - 3 and Comparative Examples 1 - 4, specifically as follows:

[0115] The test method for the setting time of the synchronous grouting material slurry in the examples and comparative examples of the present invention refers to the relevant regulations of the industry standard "Test Method Standard for Basic Properties of Building Mortars" (JGJ / T70 - 2009);

[0116] The detection of fluidity refers to the regulations of the truncated - cone fluidity test in the current national standard "Technical Specification for Application of Cement - based Grouting Materials" (GB / T50448 - 2015);

[0117] The test method for compressive strength refers to the regulations of the unconfined compressive strength test in the current industry standard "Design Code for Cement - Soil Mix Ratio" (JGJ / T233 - 2011);

[0118] The determination methods for anti - seepage pressure and anti - seepage grade refer to the relevant regulations of "Test Method Standard for Basic Properties of Building Mortars" (JGT / T70 - 2009) and "Ready - mixed Mortars" (GB / T 25181 - 2019).

[0119] The test results are shown in Table 2 and Figures 5 - 7 as follows.

[0120] Table 2 Performance test results of the synchronous grouting materials in the examples and comparative examples

[0121]

[0122] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0123] The above-described embodiments only represent several implementation manners of the present invention, and the description is relatively specific and detailed. However, it should not be construed as a limitation on the scope of the invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. A high-performance environmentally friendly synchronous grouting material, characterized in that: By weight, it includes the following components: 10-15 parts cement 15-20 parts of slag 20-30 parts of steel slag 300-320 parts of fine sand containing mud Iron sulfide 0.075-0.1 parts Graphene oxide 0.05-0.12 parts N,N-diisopropylformamide 0.03-0.09 parts 45-50 parts of water.

2. The high-performance environmentally friendly synchronous grouting material according to claim 1, characterized in that: The cement is ordinary Portland cement and / or sulphoaluminate cement.

3. The high-performance environmentally friendly synchronous grouting material according to claim 1, characterized in that: The density of the slag is 2.5-3.0 g / cm 3 , with a specific surface area of ​​370-480m 2 / kg.

4. The high-performance environmentally friendly synchronous grouting material according to claim 1, characterized in that: The steel slag has a fineness of 200-300 mesh and a density of 3.0-3.5 g / cm 3 , 28d activity value is 95%~96%.

5. The high-performance environmentally friendly synchronous grouting material according to claim 1, characterized in that: The particle size of the mud-containing fine sand is ≤20 μm, and the clay content is 15-25%.

6. The high-performance environmentally friendly synchronous grouting material according to claim 1, characterized in that: The mud-containing fine sand is obtained after shield slag is screened at multiple levels.

7. The high-performance environmentally friendly synchronous grouting material according to claim 6, characterized in that: The method for obtaining mud-containing fine sand by screening shield slag comprises the following steps: (1) The slurry of the slurry shield is transported from the tunnel to the vibrating screen of the water treatment equipment to separate the sand-containing slurry of 3-6 mm; (2) the sand-containing mud obtained in step (1) is fed into a primary cyclone for separation to obtain sand-containing mud with a particle size of less than 74 μm; (3) The sand-containing mud with a particle size of less than 74 μm enters the secondary cyclone to separate the mud-containing fine sand with a particle size of less than 20 μm.

8. The method for preparing the high-performance environmentally friendly synchronous grouting material according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, mixing cement, slag, fine sand containing mud powder and part of water to obtain a first slurry; S2, adding steel slag and iron sulfide to the first slurry, and then adding part of water to mix evenly to obtain a second slurry; S3, adding graphene oxide to part of the water, mixing, and then adding to the second slurry to obtain a third slurry; S4. Add N,N-diisopropylformamide to the remaining water, mix well, and add to the third slurry to obtain the high-performance environmentally friendly synchronous grouting material.

9. The method for preparing a high-performance, environmentally friendly synchronous grouting material according to claim 8, characterized in that: In step S1, the stirring time is 1-3 min; and / or, in step S2, the stirring time is 0.5-2 min; and / or, in step S3, the stirring time is 1-3 min; and / or, in step S4, the stirring time is 1-3 min.

10. The method for preparing a high-performance environmentally friendly synchronous grouting material according to claim 9, characterized in that: The total stirring time in step S1 to step S4 is controlled at 6-8 min.

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