Low-shrinkage high-performance grouting material and preparation method thereof

Abstract

The invention discloses a low-shrinkage high-performance grouting material and a preparation method thereof. The low-shrinkage high-performance grouting material is prepared from the following raw materials in parts by weight: 30-45 parts of ordinary Portland cement, 15-30 parts of lithium slag powder, 40-60 parts of sand, 0-5 parts of silica fume, 0-5 parts of phosphogypsum, 1.5-3 parts of a powder water reducer, 0.002-0.1 part of a plastic expanding agent, 0-1 part of a retarder, 0-0.8 part of a viscosity modifier and 0-2 parts of a defoaming agent. The lithium slag powder is prepared by drying lithium slag to constant weight at the temperature of not more than 100 DEG C and then grinding for 20-40 minutes in a ball mill, specifically, the shrinkage of the grouting material can be effectively reduced by virtue of an adsorption-release moisture mechanism and chemical activity of the lithium slag through optimal proportioning of the lithium slag and other components; and continuous internal curing is provided in the hardening process, so that the mechanical property and durability of the grouting material are improved. According to the invention, not only is the resource utilization of the lithium slag realized, but also a new thought and a technical path are provided for the development of high-performance building materials.

Description

Technical Field

[0001] The present invention relates to the technical field of resource utilization of solid waste, in particular to a low-shrinkage high-performance grouting material and a preparation method thereof. Background Art

[0002] In recent years, the new energy storage industry represented by lithium batteries has developed vigorously, promoting the rapid rise of the lithium salt industry (such as lithium carbonate, lithium hydroxide, lithium chloride, etc.). As one of the major lithium battery producers in the world, the production scale of lithium salts in China has been continuously expanding. However, in the process of lithium salt production, a large amount of lithium slag generated has become an important industrial solid waste problem that urgently needs to be solved. Generally, 8-10 tons of lithium slag will be generated for every 1 ton of lithium salt produced, and the cumulative stockpile in China over the years has reached tens of millions of tons, which not only occupies land resources but also poses a potential threat to the ecological environment.

[0003] The chemical components of lithium slag mainly include SiO2, Al2O3, Fe2O3, CaO, etc., and its mineral phases are mainly composed of quartz (SiO2), calcite (CaCO3), gypsum (CaSO4·2H2O), and andalusite (Al2O3), etc. These components and mineral phases endow lithium slag with potential activity and recycling value. However, at present, the resource utilization rate of lithium slag is still relatively low, and the problem of large-scale stockpiling urgently needs to be solved through technical means.

[0004] With the increasing global demand for green building materials and sustainable development, the research focus in the field of building materials has gradually shifted towards resource recycling and environmentally friendly materials. As an important building material, grouting materials are widely used in fields such as structural reinforcement, crack repair, and underground engineering. In particular, high-performance grouting materials, with their excellent mechanical properties, durability, and stability, have become an important part of modern construction projects. However, currently commercially available grouting materials still have significant performance defects, including the following points: 1. High shrinkage rate: Traditional cement-based grouting materials often exhibit large volume shrinkage during the hardening process, which is extremely likely to cause shrinkage cracks, thus affecting the project quality and service life. 2. Insufficient internal curing performance: In a long-term sealed and low-humidity environment, the hydration reaction of cement-based grouting materials is difficult to proceed fully, resulting in limited strength development and reduced durability. 3. Large environmental burden: Grouting materials mainly use cement as the basic raw material, and their production process is accompanied by high energy consumption and high carbon emissions, which does not conform to the development direction of green building materials. In view of the above problems, how to develop a new type of grouting material with both low shrinkage, high strength, and good internal curing performance has become a technical difficulty that urgently needs to be overcome in the field of building materials. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: in order to overcome the deficiencies existing in the prior art, a low-shrinkage high-performance grouting material and its preparation method are provided. By reasonably utilizing the porous structure and its own chemical properties of lithium slag, the shrinkage and internal curing problems existing in the existing grouting materials are solved.

[0006] The technical solution adopted by the present invention is: a low-shrinkage high-performance grouting material, and the components of the raw materials are as follows by weight: 30-45 parts of ordinary Portland cement, 15-30 parts of lithium slag powder, 40-60 parts of sand, 0-5 parts of silica fume, 0-5 parts of phosphogypsum, 1.5-3 parts of powder water reducer, 0.002-0.1 part of plastic expansion agent, 0-1 part of retarder, 0-0.8 part of viscosity regulator, 0-2 parts of defoamer;

[0007] The lithium slag powder is prepared from the industrial by-product acid-process lithium slag generated by roasting lithium spodumene by the acid method to produce lithium salts. The content of SiO2+Al2O3 in the lithium slag is greater than 75%. This type of lithium slag has good potential activity and can form rich C-S-H and C-A-S-H structures in a low-clinker system, thereby ensuring the early strength and long-term stability of the grouting material;

[0008] The lithium slag powder is made by drying the lithium slag to a constant weight at a temperature not exceeding 100°C and then grinding it in a ball mill for 20-40 minutes. The specific surface area of the lithium slag powder is 1200m 2 / kg, and D50 is about 3μm.

[0009] The lithium slag is dried to a constant weight at a temperature not exceeding 100°C. The lithium slag contains a large amount of gypsum dihydrate. Too high a drying temperature will cause the gypsum dihydrate to dehydrate and turn into hemihydrate gypsum or even soluble anhydrous gypsum. Hemihydrate gypsum will regenerate gypsum dihydrate when added with water. This reaction process will consume a large amount of free water and generate a certain amount of heat, reducing the workability of the mixture and increasing the time-dependent loss of fluidity. The grinding time should not be too short, otherwise the lithium slag particles will be too coarse and the activity will be difficult to effectively play. Continuing to increase the grinding time has little effect on improving the specific surface area, and at the same time increases energy consumption.

[0010] Further, the silica fume in the present invention is densified silica fume, its silica content is greater than 90%, the 7-day activity index is 109%, and the 28-day activity index is 117%.

[0011] Further, the plastic expansion agent in the present invention is at least one of azodicarbonamide and azodiisobutyronitrile, and the particle D50 of the azo compound ≤ 5μm to improve the consistency and stability of the mixture.

[0012] Phosphogypsum is an industrial by-product generated during the production of wet-process phosphoric acid.

[0013] Furthermore, the powder water reducer described in the present invention is a polycarboxylate water reducer or an amino sulfonate water reducer.

[0014] Furthermore, the retarder described in the present invention is one or more of boric acid, borax or tartaric acid to control the setting time of the grouting material.

[0015] Furthermore, the viscosity regulator described in the present invention is hydroxypropyl methyl cellulose ether, and its viscosity range is 50,000 - 200,000 mPa·s, which helps to adjust the fluidity and stability of the grouting material.

[0016] Furthermore, the defoamer described in the present invention is one or more of silicone defoamers, polyether defoamers, and mineral oil defoamers.

[0017] Furthermore, the sand described in the present invention is quartz sand, and the mass ratio of 40 - 70 - mesh coarse sand to 70 - 140 - mesh fine sand is 6:4 to optimize the density and mechanical strength of the grouting material.

[0018] A preparation method of a low - shrinkage high - performance grouting material is to uniformly mix each raw material in advance according to the above - mentioned mass components, add 12 - 18 parts of water, and stir for 5 minutes to obtain a low - shrinkage high - performance grouting material.

[0019] The porous structure of lithium slag has an adsorption - release water mechanism. Its large internal surface area endows the paste with a strong free - water adsorption capacity. When the grouting material is mixed, lithium slag can effectively improve water retention; after curing, it gradually releases the adsorbed water to form a continuous self - curing mechanism.

[0020] The present invention has the following advantages compared with the prior art:

[0021] 1. The grouting material of the present invention uses lithium slag as the main admixture and is supplemented with a small amount of phosphogypsum, fully exploring the resource utilization potential of industrial waste residues. Through scientific proportioning and process optimization, not only the efficient utilization of lithium slag is realized, significantly reducing the occupation of land resources by waste residue stacking, but also considerable economic benefits are created, effectively responding to the development needs of energy conservation, environmental protection and low - carbon economy.

[0022] 2. The present invention cleverly utilizes the adsorption - release water mechanism of the porous structure of lithium slag. Its large internal surface area endows the paste with a strong free - water adsorption capacity. When the grouting material is mixed, lithium slag can effectively improve water retention; after curing, it gradually releases the adsorbed water to form a continuous self - curing mechanism. This self - curing function not only effectively reduces labor and time costs, but also improves construction efficiency and the stability of material properties.

[0023] 3. The grouting material prepared by the present invention has the characteristics of high strength, low shrinkage and micro-expansion. Sulfates in lithium slag and added phosphogypsum participate in the hydration reaction and form expansive ettringite, enhancing the matrix density and alleviating autogenous shrinkage. At the same time, the addition of plastic expansion agent and lithium slag act synergistically to achieve two-stage volume compensation, effectively reducing the risks of dry shrinkage and autogenous shrinkage. This characteristic significantly reduces the cracks caused by surface shrinkage during the hardening process, greatly improving the quality and long-term stability of the material, providing a reliable guarantee for the popularization and application of high-performance building materials. Detailed implementation manners

[0024] The following details the embodiments of the present invention. The embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0025] Embodiment 1:

[0026] A low-shrinkage high-performance grouting material and its preparation method. The components of the raw materials are as follows by weight: 35 parts of ordinary Portland cement (P.O 52.5R), 15 parts of lithium slag powder with a specific surface area of 1200 m2 / kg (the content of SiO2 + Al2O3 is 81.18%), 50 parts of quartz sand, 0.5 part of phosphogypsum, 2 parts of silica fume, 1.5 parts of polycarboxylate powder water reducer, 0.08 part of azodicarbonamide plastic expansion agent, 0.05 part of borax retarder, 0.5 part of hydroxypropyl methyl cellulose ether viscosity regulator, and 0.2 part of silicone defoamer. The above raw materials are premixed evenly, and 16 parts of water are added. After stirring for 5 minutes, a low-shrinkage high-performance grouting material is obtained. The performance of the grouting material is tested according to the standard GB / T 50448-2015 "Technical Specification for Application of Cement-based Grouting Materials", and the performance test results are shown in Table 1.

[0027] Embodiment 2:

[0028] The difference from Embodiment 1 is that the components of the raw materials are as follows by weight: 40 parts of ordinary Portland cement (P.O52.5R), 20 parts of lithium slag powder with a specific surface area of 1200 m2 / kg (the content of SiO2 + Al2O3 is 81.18%), 50 parts of quartz sand, 0.5 part of phosphogypsum, 2 parts of silica fume, 1.8 parts of polycarboxylate powder water reducer, 0.06 part of azodicarbonamide plastic expansion agent, 0.05 part of borax retarder, 0.5 part of hydroxypropyl methyl cellulose ether viscosity regulator, and 0.2 part of silicone defoamer.

[0029] Embodiment 3:

[0030] The difference from Embodiment 1 is that the components of the raw materials are as follows by weight: 40 parts of ordinary Portland cement (P.O52.5R), lithium slag powder with a specific surface area of 1200 m 225 parts of lithium slag powder (SiO2 + Al2O3 content is 81.18%) per kg, 50 parts of quartz sand, 0.5 part of phosphogypsum, 2 parts of silica fume, 2.0 parts of polycarboxylate powder water reducer, 0.03 part of azodicarbonamide plastic expansion agent, 0.04 part of borax retarder, 0.4 part of hydroxypropyl methyl cellulose ether viscosity regulator, 0.2 part of silicone defoamer.

[0031] Comparative Example 1

[0032] The difference from Example 1 is that all lithium slag is replaced with 52.5 cement, that is, no lithium slag is incorporated.

[0033] Comparative Example 2

[0034] The difference from Example 1 is that the grinding time of lithium slag is 10 minutes and the specific surface area of lithium slag is 600 m2 / kg.

[0035] Comparative Example 3

[0036] The difference from Example 1 is that the chemical element composition of the used lithium slag is SiO2: 54.468%; Al2O3: 20.203%; SO3: 13.098%; CaO: 7.663%; Fe2O3: 2.497%; K2O: 0.919%; P2O5: 0.431%; other chemical elements including Cr2O3, MnO, Rb2O, NiO, SnO2, NbO, ZnO, CuO, etc. total 0.721%, that is, it has a lower SiO2 + Al2O3 content.

[0037] The relevant properties of the grouting materials for the above Examples 1, 2, 3 and Comparative Examples 1, 2, 3 were tested. Among them, the test methods for fluidity and vertical expansion rate refer to GB / T50448-2015 "Technical Specification for Application of Cementitious Grouting Materials", and the test methods for compressive strength and flexural strength refer to GB / T17671-2021 "Test Method for Cement Mortar Strength (ISO Method)". The autogenous shrinkage refers to ASTM C1698-2009 "Standard Test Method for Autogenous Shrinkage of Cement Paste and Mortar", and the drying shrinkage refers to the industry standard JC / T603-2004 "Test Method for Drying Shrinkage of Cement Mortar" for testing. The specific test results are shown in the following table:

[0038]

[0039]

[0040] As shown in Table 1, in Examples 1 - 3, as the lithium slag content gradually increased from 15 parts to 25 parts, the volume stability of the grout was significantly improved. Among them, both the 28 - day autogenous shrinkage and drying shrinkage decreased to varying degrees, showing good shrinkage control ability. At the same time, the grout maintained excellent strength performance. The 28 - day compressive strength was stable between 64 - 67 MPa, the 1 - day strength reached above 30 MPa, and the 3 - day strength exceeded 50 MPa, meeting the requirements of rapid construction and early load - bearing. In terms of fluidity, the initial fluidity of the examples was all above 330 mm, and the fluidity after 30 minutes was well maintained, indicating that the formulation system of the present invention has both workability and stability. Within the reasonable formulation range set in the present invention, the key performance indicators of the grout, such as compressive strength, shrinkage rate, and fluidity, all showed stability, indicating that the system of the present invention has good formulation adjustability and engineering adaptability. Users can flexibly adjust within the scope of the present invention according to the different requirements of early strength, fluidity, or shrinkage control in actual projects to achieve performance balance and directional optimization.

[0041] In Comparative Example 1, no lithium slag was added at all, and only ordinary Portland cement was used as the cementitious material. Although it had certain early strength, due to the lack of self - curing mechanism and micro - expansion regulation effect, its 28 - day drying shrinkage was as high as 530×10 -6 , and the autogenous shrinkage reached 105×10 -6 , much higher than that of the examples, and it was easy to cause problems such as late dry - shrinkage cracking. In Comparative Example 2, lithium slag with a low specific surface area (600 m 2 / kg) was used. Although the formula contained lithium slag, due to insufficient grinding, its reaction activity decreased significantly, the shrinkage control ability was weak, and the dry - shrinkage value was still as high as 290×10 -6 . In Comparative Example 3, the total amount of SiO2 + Al2O3 in the lithium slag used was low, and the SO3 content was high, resulting in poor internal structural stability, large shrinkage strain, and a dry - shrinkage value of 305×10 -6 , and the 28 - day compressive strength also decreased to 58 MPa.

[0042] In summary, the present invention constructs a grouting system with high - activity and high - specific - surface - area lithium slag as the main admixture, synergistically combined with a small amount of plastic expansion agent and flow - regulating components. While ensuring the strength development, it significantly reduces the drying shrinkage and autogenous shrinkage, and avoids the shrinkage - cracking problems of the traditional high - cement system. This system has the advantages of excellent mechanical properties, good construction performance, high volume stability, and high level of solid - waste resource utilization. It is suitable for application scenarios such as high - requirement structural grouting, ultra - long steel - bar anchoring, and rail transit bed filling, with extremely obvious economic and social benefits.

Claims

1. A low-shrinkage high-performance grouting material, characterized in that: The components of the raw materials are as follows by weight parts: 30 - 45 parts of ordinary Portland cement, 15 - 30 parts of lithium slag powder, 40 - 60 parts of sand, 0 - 5 parts of silica fume, 0 - 5 parts of phosphogypsum, 1.5 - 3 parts of powder water reducer, 0.002 - 0.1 part of plastic expansion agent, 0 - 1 part of retarder, 0 - 0.8 part of viscosity regulator, 0 - 2 parts of defoamer; The lithium slag powder is prepared from the industrial by - product acid - method lithium slag produced by roasting spodumene with acid method to produce lithium salts, and the content of SiO2 + Al2O3 in the lithium slag is greater than 75%; The lithium slag powder described above is made by drying lithium slag at a temperature not exceeding 100 °C until constant weight and then grinding it in a ball mill for 20 to 40 minutes. The specific surface area of the lithium slag powder is 1200 m 2 / kg, and D50 is 3 μm.

2. The low-shrinkage high-performance grouting material according to claim 1, wherein: The silica fume is densified silica fume, its silica content is greater than 90%, the 7 - day activity index is 109%, and the 28 - day activity index is 117%.

3. The low-shrinkage high-performance grouting material according to claim 1, characterized in that: The plastic expansion agent is at least one of azodicarbonamide and 2,2'-azobis(2,4 - dimethylvaleronitrile), and the particle D50 of the azo compound is ≤5μm.

4. The low-shrinkage high-performance grouting material according to claim 1, wherein: The powder water reducer is polycarboxylate water reducer or amino sulfonate water reducer.

5. The low-shrinkage high-performance grouting material according to claim 1, characterized in that: The defoamer is one or several of silicone defoamer, polyether defoamer, and mineral oil defoamer.

6. The low-shrinkage high-performance grouting material according to claim 1, wherein: The sand is quartz sand, and the mass ratio of 40 - 70 - mesh coarse sand to 70 - 140 - mesh fine sand is 6:

4.

7. The low-shrinkage high-performance grouting material according to claim 1, characterized in that: The retarder is one or several of boric acid, borax, and tartaric acid.

8. The low-shrinkage high-performance grouting material according to claim 1, wherein: The viscosity regulator is hydroxypropyl methyl cellulose ether.

9. A preparation method for the low-shrinkage high-performance grouting material according to any one of claims 1 to 8, characterized in that: Mix the raw materials in advance according to the above weight parts, add 12 - 18 parts of water, and stir for 5 minutes to obtain a low - shrinkage high - performance grouting material.

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