Solidified soil with anti-cracking and anti-shrinkage functions and preparation method thereof

Abstract

The application discloses a solidified soil with anti-cracking and anti-shrinkage functions and a preparation method thereof. The solidified soil comprises a solidified material and soil. The solidified material comprises the following components in parts by mass: blast furnace slag 50-60 parts, calcium oxide 5-8 parts, sodium silicate 15-20 parts, metakaolin 10-15 parts, sodium carbonate 2-5 parts, gamma-aminopropyl triethoxysilane 1-3 parts, phase change material microcapsules 5-10 parts, graphene oxide 1-3 parts, calcium sulfate 10-15 parts, polyethylene glycol 3-5 parts, polyvinyl alcohol 1-3 parts, aluminum sulfate 2.4-4.8 parts, sodium lignosulfonate 2-5 parts, and titanium sulfate 1.6-3.2 parts. The mass of the solidified material is not less than 6% of the mass of the soil. The solidified soil has high strength, good water stability, excellent anti-cracking and anti-shrinkage properties through the adjustment of the components in the raw materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of mud solidification, in particular to a solidified soil with anti-cracking and anti-shrinkage functions and a preparation method thereof. BACKGROUND

[0002] The solidified soil is generally composed of fine and loose soil particles and inorganic cementing materials, which is prone to cracking during maintenance and use, especially in summer construction, surface cracks of the solidified soil often occur, which affects the strength of the solidified soil and reduces the reliability of the solidified soil material, thereby limiting the application of the solidified soil material. The main reasons for the easy cracking and shrinkage of the solidified soil are as follows: the inorganic cementing material reacts with water in the soil, resulting in a decrease in the water content of the solidified soil and the generation of dry shrinkage cracks; in the initial stage of soil solidification, the inorganic cementing material releases a large amount of heat, causing the internal temperature of the soil to be higher than the surface temperature of the soil; in the later stage of solidification, the surface of the solidified soil is directly exposed to the sun, especially in summer construction, the surface temperature of the solidified soil is higher than the internal temperature, resulting in a temperature gradient between the inside and outside of the solidified soil and temperature cracks; the surface of the solidified soil is directly in contact with the air, causing the water loss rate of the surface of the solidified soil to be higher than that of the inside, and the surface temperature of the solidified soil is increased due to the direct exposure to the sun, which accelerates the water loss rate of the surface of the solidified soil, promoting the shrinkage of the surface of the solidified soil, while the inside of the solidified soil shrinks slowly, resulting in a shrinkage difference between the surface and the inside of the solidified soil and causing the solidified soil to crack. Therefore, the cracking and shrinkage of the solidified soil are mainly affected by temperature and water content, which complement each other and jointly promote the development of the cracking of the solidified soil.

[0003] Patent CN 115490497 A realizes the anti-cracking performance of the solidified soil by adding polypropylene fibers to the solidifying agent, but in order to achieve good anti-cracking performance of the solidified soil, the fibers and soil need to be fully mixed and uniform, which is difficult to achieve with existing engineering machinery equipment.

[0004] Patent application file with application number 202311855794.5 discloses a fiber reinforced composite solidifying agent for reinforcing silt composed of carbide slag, desulfurization gypsum and glass fiber, which prevents the development of cracks through the tensile and anti-pulling performance of the glass fiber, but in order to achieve good anti-cracking effect, how to uniformly mix the glass fiber with the soil will be the main reason hindering the engineering application of this method.

[0005] Patent CN117003529B uses cement, desulfurization ash, carbide slag, fly ash, soil permeation agent, high-performance water reducing agent and polyester fiber to solidify the waste soil, which adopts the same idea as the above-mentioned patent and realizes the anti-cracking effect by adding polyester fiber, but how to uniformly mix the fibers is a practical problem that is difficult to solve in the construction process of this type of method.

[0006] The patent CN111116157B reduces the cracking phenomenon of solidified soil by adding calcium sulfate and magnesium oxide in the curing agent, early expansion caused by calcium aluminate generated by calcium sulfate and late expansion of magnesium oxide, but the method mainly has the following problems: the soil is composed of granular bulk material, the internal pore is rich, in order to realize the anti-cracking effect, the expansion component content of the curing agent should correspond to the porosity of the soil, too little cannot play the effect of anti-cracking, too much will cause expansion cracking; in addition, the expansion rate of the curing agent should match the shrinkage of the soil, otherwise the deformation mismatch will more easily lead to the formation of cracks.

[0007] From the above, the existing technical means has not solved the defect that the solidified soil is easy to crack and shrink, therefore, at present, there is still an urgent need for a solidified material and method which can better solve the problem of easy cracking and shrinkage of solidified soil. SUMMARY

[0008] The purpose of the application is to provide a solidified soil with anti-cracking and anti-shrinkage functions; the second purpose of the application is to provide a preparation method of the solidified soil.

[0009] Technical scheme: the pre-mixed early-strength type fluid solidified soil provided by the application comprises a solidified material and soil, and the solidified material comprises the following components by mass fraction: blast furnace slag 50-60 parts, calcium oxide 5-8 parts, sodium silicate 15-20 parts, metakaolin 10-15 parts, sodium carbonate 2-5 parts, gamma-aminopropyl triethoxysilane 1-3 parts, phase change material microcapsule 5-10 parts, graphene oxide 1-3 parts, calcium sulfate 10-15 parts, polyethylene glycol 3-5 parts, polyvinyl alcohol 1-3 parts, aluminum sulfate 2.4-4.8 parts, sodium lignosulfonate 2-5 parts, and titanium sulfate 1.6-3.2 parts; the mass of the solidified material is not less than 6% of the mass of the soil.

[0010] The phase change material microcapsule comprises the following components by mass fraction: paraffin 8-12 parts, hexamethylene diisocyanate 1-2 parts, polyethylene glycol 1-2 parts, polyvinyl alcohol 0.38-1.1 parts, triethylamine 0.01-0.02 parts, dichloromethane 2-8 parts, and water 25-30 parts.

[0011] In the phase change material microcapsule, paraffin is used as a phase change material, and the remaining materials are used as wall materials, which have long-term stability in an alkaline and humid environment.

[0012] Preferably, the mass of the solidified material is 6-15% of the mass of the soil. For solidified soil with high strength and anti-cracking performance requirements, a high dosage can be selected, and for solidified soil with low requirements, a low dosage can be selected.

[0013] Preferably, the melting point of the paraffin is 25-40 DEG C.

[0014] Preferably, the molecular weight of the polyethylene glycol is 2000-10000.

[0015] Preferably, the molecular weight of the polyvinyl alcohol is 17000-30000.

[0016] Preferably, the sodium silicate is a powder with a modulus of 1.

[0017] The preparation method of the solidified soil with anti-cracking and anti-shrinkage functions according to the present application comprises the following steps:

[0018] (1) A certain amount of polyvinyl alcohol is weighed and dissolved in water to obtain a polyvinyl alcohol solution. The polyvinyl alcohol solution is sprayed on the soil that needs to be solidified, and mixed and stirred uniformly. The water content of the soil after spraying the polyvinyl alcohol solution is 2-3% higher than the optimal water content. A mixed material A is obtained.

[0019] (2) A certain amount of γ-aminopropyl triethoxysilane is uniformly sprayed on the material A and mixed uniformly to obtain a material B.

[0020] (3) A certain amount of blast furnace slag, metakaolin, calcium sulfate, aluminum sulfate, titanium sulfate and sodium lignosulfonate is weighed and added to the material B and mixed uniformly to obtain a material C.

[0021] (4) A certain amount of polyethylene glycol, phase change material microcapsules and graphene oxide is weighed and added to the material C and mixed and stirred to obtain a material D.

[0022] (5) A certain amount of calcium oxide, sodium silicate and sodium carbonate is weighed and added to the material D and mixed and stirred uniformly to obtain the solidified soil with anti-cracking and anti-shrinkage functions.

[0023] The optimal water content in step (1) is a basic material parameter of the soil, which can be obtained by a soil compaction test.

[0024] Preferably, the preparation method of the phase change material microcapsules comprises the following steps:

[0025] (1) Polyvinyl alcohol is added to water to completely dissolve the polyvinyl alcohol and obtain a polyvinyl alcohol solution.

[0026] (2) Paraffin is heated to above the melting point to completely melt, and then slowly added dropwise to the polyvinyl alcohol solution. Ultrasonic dispersion is adopted to form a uniform paraffin emulsion.

[0027] (3) Hexamethylene diisocyanate is poured into dichloromethane and mixed until completely dissolved to form a hexamethylene diisocyanate solution.

[0028] (4) Polyethylene glycol is poured into the hexamethylene diisocyanate solution and stirred to mix uniformly.

[0029] (5) adding the solution in step (4) into the paraffin emulsion prepared in step (2) and continuously stirring to obtain a uniform mixture;

[0030] (6) adding triethylamine dropwise into the mixture obtained in step (5) and continuously stirring to react, the temperature of the mixture is 40-50℃, the stirring time is 2-3 hours, and the mixture is cooled to room temperature after the reaction is completed;

[0031] (7) separating the solution obtained in step (6) into microcapsules, drying the separated microcapsules to obtain microcapsules with phase change function.

[0032] In step (6), the paraffin is coated by the polyurethane shell formed by the cross-linking reaction of hexamethylene diisocyanate and polyethylene glycol as the core material, the shell uniformly coats the surface of the paraffin emulsion droplets, thereby forming a stable microcapsule structure to form the microcapsules.

[0033] Preferably, in step (7), the microcapsules are separated by placing the solution into a centrifuge, the centrifuge speed is 3000-5000 rpm, and the time is 10-20 min.

[0034] Preferably, in step (7), the drying temperature is 40-50℃.

[0035] Invention mechanism:

[0036] The present patent achieves the purpose of anti-cracking and shrinkage through temperature control, expansion, moisture retention and toughening, and the main mechanism is as follows:

[0037] (1) The shrinkage and cracking of the solidified soil are most likely to occur during the curing stage. The solidified material hydrates after being exposed to water, releasing a large amount of heat, which is absorbed by the phase change microcapsules, keeping the temperature of the solidified soil relatively constant. In addition, when the solidified soil is exposed to sunlight in summer, the surface temperature of the solidified soil rises quickly, resulting in a temperature difference between the surface and the interior of the solidified soil. In the present invention, the phase change microcapsules can store a portion of the heat from the sunlight, and the graphene oxide can enhance the thermal conductivity of the solidified soil, allowing the heat on the surface of the solidified soil to be transferred to the interior of the solidified soil, reducing the temperature gradient of the solidified soil and the cracking caused by the temperature gradient. Moreover, due to the addition of the phase change microcapsules, the temperature of the soil remains relatively stable, and combined with the water-retaining function of the polyethylene glycol, the loss of water on the surface of the solidified soil caused by sunlight exposure can be significantly reduced, reducing the probability of surface cracking.

[0038] (2) Blast furnace slag and aged soil undergo inorganic polymerization reaction under the action of sodium silicate, calcium oxide and sodium carbonate. In the process of generating geopolymer, free water in the soil is consumed, resulting in a decrease in soil moisture content. The decrease in moisture content will also cause the soil to shrink and crack. To compensate for this shrinkage, sulfate in the curing agent will react with calcium oxide, blast furnace slag and sodium silicate to form hydrated products of calcite, which will cause volume expansion, compensate for the shrinkage caused by the decrease in moisture content, and reduce the risk of shrinkage and cracking of the cured soil.

[0039] (3) After hydration, the solidified material ionizes into aluminum and titanium ions. These ions can form coordinate bonds with the hydroxyl groups in polyvinyl alcohol, causing cross-linking between polymers and forming a spatial network structure in the soil skeleton. This creates a fiber-like soil reinforcement effect, effectively dispersing stress, increasing the tensile strength of the solidified soil, and preventing early cracking. The amino group at one end of the γ-aminopropyltriethoxysilane molecule can react with the hydroxyl groups in polyethylene glycol, while the siloxy group at the other end can bond with the silicates and aluminates in the geopolymer. This can form a bridge between polyethylene glycol and the geopolymer, promoting the formation of a spatial cross-linking network along the polyvinyl alcohol molecular chains attached to the surface of the soil particles. This further enhances the fiber-like reinforcement effect formed after the polyvinyl alcohol cross-links, effectively limiting the mid-to-late stage cracking of the solidified soil.

[0040] In summary, based on the synergistic effect of temperature control, moisture retention, expansion compensation, and spatial cross-linking framework construction in this technical solution, the curing agent can achieve the function of preventing cracking and shrinkage.

[0041] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The solidified soil has high strength and good water stability through the adjustment of each component in the raw materials, and has excellent anti-cracking and anti-shrinkage properties; (2) The total drying shrinkage coefficient of the solidified soil can reach 0.24‰, and the maximum thermal shrinkage coefficient is 0.296‰; (3) The preparation method is simple. Detailed Implementation

[0042] The technical solution of the present invention will be further described below with reference to the embodiments.

[0043] Examples 1-3

[0044] A type of solidified soil with crack resistance and shrinkage prevention includes a solidification material and soil, and the raw material composition of the solidification material is shown in Table 1.

[0045] Table 1. Raw material proportions (parts by mass) of the cured materials in Examples 1-3

[0046]

[0047]

[0048] The raw materials for the phase change material microcapsules include, by mass parts, the following components: paraffin 8-12 parts, hexamethylene diisocyanate 1-2 parts, polyethylene glycol 1-2 parts, polyvinyl alcohol 0.38-1.1 parts, triethylamine 0.01-0.02 parts, dichloromethane 2-8 parts, and water 25-30 parts. The raw material proportions of the phase change material microcapsules of Examples 1-3 are shown in Table 2.

[0049] Table 2 Raw material proportions of phase change material microcapsules of Examples 1-3 (mass parts)

[0050]

[0051] The method for preparing the phase change material microcapsules is as follows:

[0052] (1) Polyvinyl alcohol is added to water to completely dissolve the polyvinyl alcohol, obtaining a polyvinyl alcohol solution;

[0053] (2) Paraffin is heated to above the melting point to completely melt it, then slowly added to the polyvinyl alcohol solution, and an ultrasonic wave is used to disperse to form a uniform paraffin emulsion;

[0054] (3) Hexamethylene diisocyanate is poured into dichloromethane and mixed until completely dissolved, forming a hexamethylene diisocyanate solution;

[0055] (4) Polyethylene glycol is poured into the hexamethylene diisocyanate solution and stirred to mix evenly;

[0056] (5) The solution in step (4) is added to the paraffin emulsion and continuously stirred, obtaining a uniform mixture;

[0057] (6) Triethylamine is slowly added to the mixture obtained in step (5) and continuously stirred, with a stirring time of 2 hours, a stirring speed of 1000 rpm, and a temperature of 40-50°C, and after the reaction is complete, the solution is cooled to room temperature;

[0058] (7) The solution obtained in the above step is placed in a centrifuge with a speed of 4000 rpm for 15 minutes to separate the microcapsules, and the separated microcapsules are placed in a 40-50°C oven to dry, obtaining the microcapsules with phase change function.

[0059] The method for preparing the solidified soil includes the following steps:

[0060] (1) according to the mass fraction of polyvinyl alcohol, and put in water to dissolve, prepare polyvinyl alcohol solution, polyvinyl alcohol solution is sprayed on the need to be cured soil (the cured soil is low liquid limit silty clay with the optimum water content of 15.3%, the amount of curing material is 8% of the mass of soil, the water content of the cured soil after spraying polyvinyl alcohol solution is 17.3%), and mixed and stirred uniformly, to obtain the mixed material A;

[0061] (2) according to the mass fraction of γ-aminopropyl triethoxysilane, and uniformly spray γ-aminopropyl triethoxysilane on material A, and mix and stir uniformly to obtain material B;

[0062] (3) according to the mass fraction of the following raw materials: blast furnace slag, metakaolin, calcium sulfate, aluminum sulfate, titanium sulfate, sodium lignosulfonate, add to material B and mix and stir, to obtain material C;

[0063] (4) according to the mass fraction of polyethylene glycol, phase change material microcapsule, graphene oxide, and add to material C, mix and stir to obtain material D;

[0064] (5) finally, according to the mass fraction of the following raw materials: calcium oxide, sodium silicate, sodium carbonate, and add to material D, mix and stir uniformly to obtain the cured soil with anti-cracking and shrinkage prevention function.

[0065] Take the cured soil prepared in examples 1-3, pour into three saturated containers, to prepare the preparation sample with diameter (50mm) x height (50mm), compaction degree of 97%, according to "highway engineering inorganic binder stabilized material material test procedures (JTG E51-2009)", test the sample, and the test results are shown in table 3:

[0066] Table 3 test results of examples 1-3

[0067]

[0068]

[0069] The test results show that the three kinds of mix proportion of the curing agent prepared in the examples have good curing effect on soft soil, and the unconfined compressive strength of the sample after normal maintenance for 7d can reach 4.07MPa; due to the three-dimensional crosslinked structure generated inside the sample, the toughness of the sample is improved, the sample is complete in appearance after 5 times of freeze-thaw cycle, and no cracks appear on the surface of the sample, and the strength loss rate of the sample is only 2%-3%. The total dry shrinkage coefficient and the maximum temperature shrinkage coefficient of the sample are also very small, which shows that the sample has good anti-cracking and anti-shrinkage function.

[0070] Comparative example 1

[0071] The same as example 3, except that the raw materials of the present comparative example include, by mass fraction: blast furnace slag 60 parts, calcium oxide 8 parts, sodium silicate 20 parts, metakaolin 15 parts, and sodium carbonate 5 parts. Preparation method: the blast furnace slag, metakaolin are added into the low liquid limit clay and mixed and stirred uniformly to obtain material C, then the calcium oxide, sodium silicate, and sodium carbonate are added into the material C and mixed and stirred uniformly to obtain the material of comparative example 1.

[0072] The test results are shown in Table 4.

[0073] Table 4 Test results of comparative examples

[0074]

[0075] The test results show that: since the comparative example 1 only has components providing cementitious materials, the performances of the sample are greatly reduced, especially after freeze-thaw cycles, the sample is broken and cannot realize the functions of anti-cracking and anti-shrinkage.

[0076] Comparative example 2

[0077] The same as example 3, except that the raw materials of the present comparative example include, by mass fraction: blast furnace slag 60, calcium oxide 8, sodium silicate 20, metakaolin 15, sodium carbonate 5, calcium sulfate 15, aluminum sulfate 4.8, and titanium sulfate 3.2.

[0078] Preparation method: the following raw materials are weighed according to the mass fraction: blast furnace slag, metakaolin, calcium sulfate, aluminum sulfate, and titanium sulfate, which are added into the low liquid limit clay and mixed and stirred to obtain material C; then the following raw materials are weighed according to the mass fraction: calcium oxide, sodium silicate, and sodium carbonate, which are added into the material C and mixed and stirred uniformly to obtain the material of comparative example 2.

[0079] The test results are shown in Table 4.

[0080] The test results show that: although the performance of the comparative example 2 is improved compared with the comparative example 1, since the spatial cross-linking structure cannot be well formed inside the sample, the performances of the comparative example 2 are still greatly reduced compared with the examples, the sample is broken after 5 freeze-thaw cycles, and cannot realize the functions of anti-cracking and anti-shrinkage.

[0081] Comparative example 3

[0082] The same as example 3, except that the raw materials of the present comparative example include, by mass fraction: blast furnace slag 60 parts, calcium oxide 8 parts, sodium silicate 20 parts, metakaolin 15 parts, sodium carbonate 5 parts, calcium sulfate 15 parts, polyethylene glycol 5 parts, polyvinyl alcohol 3 parts, aluminum sulfate 4.8 parts, sodium lignosulfonate 5 parts, and titanium sulfate 3.2 parts.

[0083] Preparation method: polyvinyl alcohol is weighed according to the mass fraction, polyvinyl alcohol solution is prepared, the polyvinyl alcohol solution is sprayed on the soil to be solidified, and is uniformly mixed and stirred to obtain a mixed material A. The following raw materials are weighed according to the mass fraction: blast furnace slag, metakaolin, calcium sulfate, aluminum sulfate, titanium sulfate, sodium lignosulfonate, and are added to the material A for mixing and stirring, and the mixed and stirred material C is obtained; polyethylene glycol is weighed according to the mass fraction, and is added to the material C for mixing and stirring to obtain a material D; finally, the following raw materials are weighed according to the mass fraction: calcium oxide, sodium silicate, and sodium carbonate, and are added to the material D for uniform mixing and stirring, and the material of the present comparative example 3 is obtained.

[0084] The sample is tested according to the “Highway Engineering Inorganic Binder Stabilized Material Material Test Specification (JTG E51-2009)”, and the test results are shown in Table 4.

[0085] The test results show that: due to the lack of γ-aminopropyl triethoxysilane, phase change material microcapsules and graphene oxide, the strengthening effect of the space cross-linking structure on the soil skeleton is weakened, and the influence of temperature on the sample is increased, so although the sample in the present comparative example 3 does not break, there are cracks on the surface of the sample, and after 5 freeze-thaw cycles, the strength decreases more, in addition, the shrinkage resistance of the sample still has a large gap compared with example 3.

[0086] Comparative example 4

[0087] The same as example 3, except that the raw materials of the present comparative example include, by mass fraction: blast furnace slag 60 parts, calcium oxide 8 parts, sodium silicate 20 parts, metakaolin 15 parts, sodium carbonate 5 parts, γ-aminopropyl triethoxysilane 3 parts, calcium sulfate 15 parts, polyethylene glycol 5 parts, polyvinyl alcohol 3 parts, aluminum sulfate 4.8 parts, sodium lignosulfonate 5 parts, and titanium sulfate 3.2 parts.

[0088] Preparation method: the polyvinyl alcohol was weighed according to the mass fraction, the polyvinyl alcohol solution was prepared, the polyvinyl alcohol solution was sprayed on the soil to be solidified, and the mixture was uniformly mixed and stirred to obtain a mixed material A. Then, the γ-aminopropyl triethoxysilane was weighed according to the mass fraction, and the γ-aminopropyl triethoxysilane was uniformly sprayed on the material A and uniformly mixed to obtain a material B. The following raw materials were weighed according to the mass fraction: blast furnace slag, metakaolin, calcium sulfate, aluminum sulfate, titanium sulfate, and sodium lignosulfonate, which were added to the material B and mixed and stirred to obtain a material C; polyethylene glycol was weighed according to the mass fraction and added to the material C, and mixed and stirred to obtain a material D; finally, the following raw materials were weighed according to the mass fraction: calcium oxide, sodium silicate, and sodium carbonate, which were added to the material D and mixed and stirred uniformly to obtain the material of Comparative Example 4.

[0089] The sample was tested according to the Highway Engineering Inorganic Binder Stabilized Material Material Test Specification (JTG E51-2009), and the test results are shown in Table 4.

[0090] The test results show that: due to the lack of phase change material microcapsules and graphene oxide, the temperature sensitivity of the sample increases, and the sample in Comparative Example 4 has microcracks on the surface after 5 cycles of dry-wet cycles, and the strength loss rate of the sample is 12.6%, which is higher than that of Example 3. In addition, due to the microcracks on the surface of the sample, the integrity of the sample is reduced, resulting in a decrease in the shrinkage resistance of the sample compared with Example 3.

[0091] Comparative Example 5

[0092] The same as Example 3, except that the raw materials of the present comparative example include: blast furnace slag 60 parts, calcium oxide 8 parts, sodium silicate 20 parts, metakaolin 15 parts, sodium carbonate 5 parts, phase change material microcapsules 10 parts, graphene oxide 3 parts, calcium sulfate 15 parts, polyethylene glycol 5 parts, aluminum sulfate 4.8 parts, sodium lignosulfonate 5 parts, and titanium sulfate 3.2 parts.

[0093] Preparation method: the following raw materials were weighed according to the mass fraction: blast furnace slag, metakaolin, calcium sulfate, aluminum sulfate, titanium sulfate, and sodium lignosulfonate, which were added to the low liquid limit clay and mixed and stirred to obtain a material C; polyethylene glycol, phase change material microcapsules, and graphene oxide were weighed according to the mass fraction and added to the material C, and mixed and stirred to obtain a material D; finally, the following raw materials were weighed according to the mass fraction: calcium oxide, sodium silicate, and sodium carbonate, which were added to the material D and mixed and stirred uniformly to obtain the material of Comparative Example 5.

[0094] According to the Highway Soil Test Specification (JTG 3430-2020), the compressive strength of the sample was determined, and the test results are shown in Table 4.

[0095] The test results show that: due to the lack of polyvinyl alcohol and γ-aminopropyl triethoxysilane, the cured material cannot form a good spatial crosslinking network in the soil. The sample in Comparative Example 5 has micro-cracks on the surface after 5 cycles of dry-wet, and the strength loss rate of the sample is 21.3%, which is significantly higher than the strength loss rate in Example 3. In addition, the shrinkage resistance of the sample is also significantly reduced compared with the examples.

[0096] Comparative Example 6

[0097] The same as Example 3, except that the raw materials of the present comparative example include, by mass fraction: γ-aminopropyl triethoxysilane 3, phase change material microcapsule 10, graphene oxide 3, calcium sulfate 15, polyethylene glycol 5, polyvinyl alcohol 3, aluminum sulfate 4.8, sodium lignosulfonate 5 and titanium sulfate 3.2.

[0098] Preparation method: polyvinyl alcohol is weighed according to the mass fraction, polyvinyl alcohol solution is prepared, and the polyvinyl alcohol solution is sprayed on the soil to be cured and mixed and stirred uniformly to obtain mixed material A. Then, γ-aminopropyl triethoxysilane is weighed according to the mass fraction, and the γ-aminopropyl triethoxysilane is uniformly sprayed on material A and mixed and stirred uniformly to obtain material B. The following raw materials are weighed according to the mass fraction: calcium sulfate, aluminum sulfate, titanium sulfate, sodium lignosulfonate, which are added to material B and mixed and stirred to obtain material C; polyethylene glycol, phase change material microcapsule and graphene oxide are weighed according to the mass fraction and added to material C to obtain the material of Comparative Example 6.

[0099] According to the Highway Geotechnical Test Code (JTG 3430-2020), the compressive strength of the sample is determined, and the test results are shown in Table 4.

[0100] The test results show that: due to the lack of cementitious components in the curing material and the lack of the reinforcing effect of the spatial crosslinking structure on the soil skeleton, the sample in Comparative Example 6 directly breaks after 5 cycles of dry-wet. In addition, the other performances of the sample are also significantly reduced compared with Example 3, and the anti-cracking and anti-shrinkage effects cannot be achieved.

Claims

1. A type of solidified soil with anti-cracking and anti-shrinkage properties, characterized in that, The product includes solidification materials and soil. The solidification materials, by weight, consist of the following components: 50-60 parts blast furnace slag, 5-8 parts calcium oxide, 15-20 parts sodium silicate, 10-15 parts metakaolin, 2-5 parts sodium carbonate, 1-3 parts γ-aminopropyltriethoxysilane, 5-10 parts phase change material microcapsules, 1-3 parts graphene oxide, 10-15 parts calcium sulfate, 3-5 parts polyethylene glycol, 1-3 parts polyvinyl alcohol, 2.4-4.8 parts aluminum sulfate, 2-5 parts sodium lignosulfonate, and 1.6-3.2 parts titanium sulfate. The solidification materials constitute no less than 6% of the soil weight. The phase change material microcapsules, by weight, contain the following components: 8-12 parts paraffin, 1-2 parts hexamethylene diisocyanate, 1-2 parts polyethylene glycol, 0.38-1.1 parts polyvinyl alcohol, 0.01-0.02 parts triethylamine, 2-8 parts dichloromethane, and 25-30 parts water. The preparation method of the phase change material microcapsules includes the following steps: (1) Add polyvinyl alcohol to water to completely dissolve the polyvinyl alcohol and obtain a polyvinyl alcohol solution; (2) Heat the paraffin wax to above its melting point to melt it completely, then add it dropwise to a polyvinyl alcohol solution and disperse it using ultrasonic waves to form a uniform paraffin wax emulsion; (3) Pour hexamethylene diisocyanate into dichloromethane and mix until completely dissolved to form a hexamethylene diisocyanate solution; (4) Pour polyethylene glycol into the hexamethylene diisocyanate solution and stir to mix it evenly; (5) Add the mixture obtained in step (4) to the paraffin emulsion prepared in step (2) and stir continuously to obtain a uniform mixture; (6) Add triethylamine dropwise to the mixture obtained in step (5) and stir continuously. The temperature of the mixture is 40~50℃ and the stirring time is 2~3 hours. After the reaction is completed, cool to room temperature. (7) Separate the microcapsules from the solution obtained in step (6), and dry the separated microcapsules to obtain microcapsules with phase change function.

2. The solidified soil with anti-cracking and anti-shrinkage function according to claim 1, characterized in that, The mass of the solidified material is 6-15% of the mass of the soil.

3. The solidified soil with anti-cracking and anti-shrinkage function according to claim 1, characterized in that, The melting point of the paraffin is 25~40℃.

4. The solidified soil with anti-cracking and anti-shrinkage function according to claim 1, characterized in that, The molecular weight of the polyethylene glycol is 2000~10000.

5. The solidified soil with anti-cracking and anti-shrinkage function according to claim 1, characterized in that, The molecular weight of the polyvinyl alcohol is 17,000 to 30,000.

6. The solidified soil with anti-cracking and anti-shrinkage function according to claim 1, characterized in that, The sodium silicate is in powder form with a modulus of 1.

7. The solidified soil with anti-cracking and anti-shrinkage function according to claim 1, wherein in the preparation method of the phase change material microcapsules, the separation of microcapsules in step (7) is as follows: the solution is placed in a centrifuge, the centrifuge speed is 3000~5000 rpm, the time is 10~20 min, and the microcapsules are separated.

8. In the method for preparing the phase change material microcapsules according to claim 1, the drying temperature in step (7) is 40~50℃.

9. A method for preparing solidified soil with anti-cracking and anti-shrinkage function as described in any one of claims 1 to 8, characterized in that, Includes the following steps: (1) Weigh polyvinyl alcohol, add it to water to dissolve it to obtain a polyvinyl alcohol solution, spray the polyvinyl alcohol solution onto the soil that needs to be solidified, and mix and stir evenly. The moisture content of the soil after spraying the polyvinyl alcohol solution is 2~3% higher than the optimum moisture content, and the mixed material A is obtained. (2) Weigh out γ-aminopropyltriethoxysilane and spray it evenly onto material A, mix it evenly, and obtain material B; (3) Weigh out blast furnace slag, metakaolin, calcium sulfate, aluminum sulfate, titanium sulfate and sodium lignosulfonate, add them to material B and mix them evenly to obtain material C; (4) Weigh out polyethylene glycol, phase change material microcapsules and graphene oxide, add them to material C, mix and stir to obtain material D; (5) Weigh calcium oxide, sodium silicate and sodium carbonate, add them to material D, mix and stir evenly to obtain the solidified soil with anti-cracking and anti-shrinkage function.

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