CN116103051A - Expansive soil modifier and modifying method - Google Patents
Expansive soil modifier and modifying method Download PDFInfo
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- CN116103051A CN116103051A CN202310142838.3A CN202310142838A CN116103051A CN 116103051 A CN116103051 A CN 116103051A CN 202310142838 A CN202310142838 A CN 202310142838A CN 116103051 A CN116103051 A CN 116103051A
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- 239000003607 modifier Substances 0.000 title claims abstract description 78
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- 230000006872 improvement Effects 0.000 claims abstract description 52
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- -1 polypropylene Polymers 0.000 claims abstract description 26
- 229920001155 polypropylene Polymers 0.000 claims abstract description 26
- 241000609240 Ambelania acida Species 0.000 claims abstract description 24
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- 238000005507 spraying Methods 0.000 claims abstract description 21
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- 229920005668 polycarbonate resin Polymers 0.000 claims abstract description 12
- 239000004431 polycarbonate resin Substances 0.000 claims abstract description 12
- 229920002635 polyurethane Polymers 0.000 claims abstract description 12
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- 239000000725 suspension Substances 0.000 claims abstract description 12
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- 229910021586 Nickel(II) chloride Inorganic materials 0.000 description 1
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- JRMUNVKIHCOMHV-UHFFFAOYSA-M tetrabutylammonium bromide Chemical compound [Br-].CCCC[N+](CCCC)(CCCC)CCCC JRMUNVKIHCOMHV-UHFFFAOYSA-M 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D17/00—Excavations; Bordering of excavations; Making embankments
- E02D17/20—Securing of slopes or inclines
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K17/00—Soil-conditioning materials or soil-stabilising materials
- C09K17/14—Soil-conditioning materials or soil-stabilising materials containing organic compounds only
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K17/00—Soil-conditioning materials or soil-stabilising materials
- C09K17/14—Soil-conditioning materials or soil-stabilising materials containing organic compounds only
- C09K17/18—Prepolymers; Macromolecular compounds
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K17/00—Soil-conditioning materials or soil-stabilising materials
- C09K17/40—Soil-conditioning materials or soil-stabilising materials containing mixtures of inorganic and organic compounds
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K17/00—Soil-conditioning materials or soil-stabilising materials
- C09K17/52—Mulches
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K2103/00—Civil engineering use
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Soil Sciences (AREA)
- Mining & Mineral Resources (AREA)
- General Engineering & Computer Science (AREA)
- Inorganic Chemistry (AREA)
- Structural Engineering (AREA)
- Civil Engineering (AREA)
- Paleontology (AREA)
- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
- Soil Conditioners And Soil-Stabilizing Materials (AREA)
Abstract
An expansive soil modifier and a modifying method, wherein the expansive soil modifier comprises a polycarbonate resin-based suspension, a polyurethane adhesive and a hydrophobic magnetic ionic liquid. The expansive soil modifier comprises polypropylene fibers, bagasse ash and hydrophobic magnetic ionic liquid. The expansive soil improvement method is to divide the expansion and contraction grade according to the actual condition of the expansive soil and then determine the improvement mode. The improvement method comprises (a) spraying expansive soil modifier; (b) laying a surface modifying layer; (c) The surface modifying layer is paved and the expansive soil modifier is sprayed in a combined deep layer. The invention can permanently and remarkably inhibit the swelling and shrinkage of the expansive soil and improve the shear strength; the raw materials used come from recycled materials, so that the waste is recycled, and the environmental pollution is small.
Description
Technical Field
The invention relates to the technical field of geotechnical engineering. In particular to an expansive soil modifier and a modifying method.
Background
The expansive soil is clay particles in the soil and mainly comprises hydrophilic minerals, and has remarkable deformation characteristics of water absorption expansion and water loss shrinkage. The water-absorbing and water-losing composite material has the characteristics of water-absorbing expansion, water-losing shrinkage, repeated expansion and contraction deformation, water-soaking bearing capacity attenuation, dry shrinkage crack development and the like, and the properties are extremely unstable. There is thus a need for a method of modifying expansive soil to reduce the expansibility of expansive soil.
The prior method for improving the expansive soil mainly comprises two methods of physical improvement and chemical improvement. One of the physical improvement methods is to coat a hydrophobic material on the surface of the expansive soil so that moisture in the atmosphere cannot easily enter the interior of the expansive soil body. But the existing hydrophobic material is single, and the service period is short under severe environment. One of the chemical improvement methods is to use a chemical agent to exchange ions with the expansive soil body so as to permanently change the crystal layer structure of the expansive soil. However, the method has the defects that the use of chemical reagents can bring certain pollution to the environment, and the effect time is slower. Another chemical modification method modifies expansive soil by using polymers which enhance the connection between soil particles through packing, mechanical tooth physical action, thereby reducing the expansibility of expansive soil and enhancing the strength of expansive soil, but has limited modification effect.
Therefore, there is a need in the art to develop a method for improving expansive soil with flexible use, good improvement effect and ecological environmental protection.
Disclosure of Invention
The invention aims to provide an expansive soil modifier and an expansive soil modifying method, which can flexibly use an expansive soil modifying mode, and has good modifying effect and ecological environment protection.
The technical scheme of the invention is as follows: provided are an expansive soil improver and an improvement method, the expansive soil improver comprising:
(a) A polycarbonate resin-based suspension;
(b) Hydrophobic magnetic ionic liquids;
the structural formula of the hydrophobic magnetic ionic liquid is shown as the following formula (I):
(c) A polyurethane adhesive;
the preparation is carried out according to the parts by weight: 100 parts of polycarbonate resin-based suspension, 2-5 parts of polyurethane adhesive and 20-30 parts of hydrophobic magnetic ionic liquid.
The expansive soil modifier has the functions of physical water repellency, polymer network wrapping, chemical ion exchange modification of the expansive soil by hydrophobic magnetic ionic liquid and the like. The polyurethane adhesive is used for enhancing the compatibility between the polycarbonate resin-based suspension and the expansive soil and stabilizing the internal structure of the expansive soil.
The expansive soil improvement method comprises (1) firstly according to the free expansion and shrinkage rate delta of expansive soil ef Dividing the swelling grade of the swelling soil, (2) selecting different improvement modes according to the swelling grade;
the grade of the expansion and shrinkage of the divided expansion soil is as follows:
(a) If delta is 40% or less ef If the expansion and shrinkage grade is less than or equal to 60 percent, selecting an improvement mode of spraying the expansive soil modifier;
(b) If 60% is less than or equal to delta ef If the expansion and contraction grade is less than or equal to 75 percent, selecting an improvement mode of paving a surface improvement layer;
(c) If 75% is less than or equal to delta ef And if the expansion and contraction grade is less than or equal to 90 percent, the expansion and contraction grade is grade I. Then a surface modifying layer is paved in combination with deep spraying of expansive soil modifier modifying mode is selected.
The expansive soil improvement method comprises the following steps:
1) If the swelling grade of the swelling soil is III grade, the swelling soil improvement step of spraying the swelling soil modifier is as follows:
(a) Mixing polycarbonate resin-based suspension, hydrophobic magnetic ionic liquid and polyurethane adhesive according to a required proportion to obtain an expansive soil modifier;
(b) Uniformly spraying the expansive soil modifier obtained in the step (a) on the surface of soil to be modified;
2) If the swelling grade of the swelling soil is grade II, the swelling soil improvement step of selecting and paving the surface improvement layer is as follows:
(a) Digging out a part of the expansive soil body to be improved on the surface layer of the expansive soil structure to be improved;
(b) Determining the optimal water content of the expansive soil according to the compaction test;
(c) Uniformly mixing (a) polypropylene fibers in a desired ratio; (b) bagasse ash; (c) Hydrophobic magnetic ionic liquid to obtain expansive soil modifier slurry;
(d) Uniformly mixing the expansive soil modifier slurry prepared in the step (c) with expansive soil to be modified, wherein the mixing ratio of the expansive soil modifier slurry to the weight of the expansive soil to be modified is 1/8-1/7;
(e) Adding water to the uniformly mixed expansive soil modifier slurry obtained in the step (d) and expansive soil to be modified according to the optimal water content obtained in the step (b), and uniformly stirring to obtain the modified expansive soil.
(f) Laying a surface modification layer of 30 cm-50 cm on the construction surface of the modified expansive soil obtained in the step (d), and then maintaining for 3-4 days under natural conditions.
3) If the swelling grade of the swelling soil is grade I, the swelling soil improvement step of paving a surface improvement layer and spraying a swelling soil modifier in a combined deep layer is selected as follows:
(a) Digging out a part of the expansive soil body to be improved on the surface layer of the expansive soil structure to be improved;
(b) Determining the optimal water content of the expansive soil according to the compaction test;
(c) Mixing polycarbonate resin-based suspension, hydrophobic magnetic ionic liquid and polyurethane adhesive according to a required proportion to obtain an expansive soil modifier;
(d) Uniformly spraying the expansive soil modifier obtained in the step (c) on the surface of the structure from which the surface soil body is excavated;
(e) Repeating the step (d) for 3-5 times to ensure that the total amount of the sprayed expansive soil modifier is 1.2-1.6 kg/square meter expansive soil;
(f) Uniformly mixing polypropylene fiber, bagasse ash and hydrophobic magnetic ionic liquid according to a required proportion to obtain expansive soil modifier slurry;
(g) Uniformly mixing the expansive soil modifier slurry prepared in the step (f) with expansive soil to be modified, wherein the mixing ratio of the expansive soil modifier slurry to the weight of the expansive soil to be modified is 1/8-1/7;
(h) Adding water to the uniformly mixed expansive soil modifier slurry obtained in the step (g) and expansive soil to be modified according to the optimal water content obtained in the step (c), and uniformly stirring to obtain the modified expansive soil.
(i) And (3) paving a surface modification layer of 30 cm-50 cm on the construction surface of the modified expansive soil obtained in the step (h), and then keeping the surface modification layer for 3-4 days under natural conditions.
Step 2) the surface modification layer is paved by modified expansive soil, and the modified expansive soil comprises (a) expansive soil modifier slurry; (b) The expansive soil is to be improved,
the expansive soil modifier slurry is prepared from the following components in parts by weight:
(a) Polypropylene fibers; 0.5-1 part of polypropylene fiber,
(b) Hydrophobic magnetic ionic liquids; 9-14 parts of hydrophobic magnetic ionic liquid,
(c) Bagasse ash: 85-90.5 parts of bagasse ash.
The polypropylene fiber source is a waste medical mask, and the preparation method of the polypropylene fiber comprises the following steps: sterilizing, melting, cooling and crushing the waste mask to obtain fiber base solution, preparing fiber tows through a spinning box, and finally shaping and drying to obtain the polypropylene fibers. According to the invention, the waste mask is prepared into the regenerated polypropylene fiber, so that medical waste is reused, the expansion rate of the expansive soil can be reduced, and the shearing strength of the expansive soil can be improved.
The bagasse ash contains SiO as main component 2 The improvement mechanism of the bagasse ash on the expansive soil mainly comprises ion exchange action, cementing action, filling action and adsorption action on the surface of the bagasse ash, and the combination of the reinforcement action of the polypropylene fiber and the ion exchange action and hydrophobic action of the hydrophobic magnetic ionic liquid can realize permanent reduction of the expansion rate of the expansive soil and increase of the shearing strength of the expansive soil.
Bagasse is a waste material in the sugar production chain, the burned product of which has a high content of SiO 2 . The invention combines bagasse ash with expansive soil, not only reutilizes agricultural waste resources, but also permanently reduces the expansion rate of the expansive soil and improves the shearing strength of the expansive soil
The bagasse ash is waste bagasse combustion products with the granularity of 60-110 meshes.
The polypropylene fiber is regenerated fiber with the diameter of 1mm and the length of 10-20mm prepared by using the waste medical mask.
The expansive soil improvement method is applied to side slope engineering.
The preparation method of the improved expansive soil comprises the following steps:
(1) Uniformly mixing (a) polypropylene fibers in a desired ratio; (b) bagasse ash; (c) Hydrophobic magnetic ionic liquid to obtain expansive soil modifier slurry;
(2) Uniformly mixing the expansive soil modifier slurry prepared in the step (1) with expansive soil to be modified, wherein the mixing ratio of the expansive soil modifier slurry to the weight of the expansive soil to be modified is 1/8-1/7;
(3) Adding water into the uniformly mixed expansive soil modifier slurry obtained in the step (2) and the expansive soil to be modified according to the optimal water content of the original expansive soil, and uniformly stirring to obtain the modified expansive soil.
Compared with the prior art, the invention has the beneficial effects that:
(1) Different improvement modes can be selected according to different expansion and contraction grades of the expansive soil, so that the improvement requirement of the expansive soil and the maximization of economic benefit can be simultaneously met;
(2) The expansive soil modifier has the functions of physical water repellency, polymer network wrapping, chemical ion exchange improvement of the expansive soil by hydrophobic magnetic ionic liquid and the like, wherein polyurethane is used as an adhesive for enhancing the compatibility between the polycarbonate resin-based suspension and the expansive soil, stabilizing the internal structure of the expansive soil, reducing the expansion rate of the expansive soil and improving the shearing strength of the expansive soil;
(3) In the improved expansive soil, the expansion rate of the expansive soil is permanently reduced and the shearing strength of the expansive soil is improved through the filling effect of bagasse ash, the reinforcement effect of polypropylene fibers and the ion exchange effect between the hydrophobic magnetic ionic liquid and the expansive soil;
(4) The preparation and improvement method is simple, the used raw materials are environment-friendly, and the reutilization of waste is realized.
Drawings
FIG. 1 is a sectional view of an expansive soil slope modified by applying a surface modifying layer and spraying expansive soil modifier in combination with deep layers in accordance with an embodiment of the present invention.
Marked in the figure as: a slope expansive soil layer 1, a spraying modifier modifying layer 2 and a surface modifying layer 3.
Detailed Description
The technical scheme of the present invention will be clearly and completely described in the following in connection with the embodiments of the present invention.
The raw materials and components used in the examples were all purchased commercially.
Hydrophobic magnetic ionic liquids were prepared as described in example 1 of chinese patent application 202210259349.1. The preparation method comprises the following steps: 1, 3-tetramethyl guanidine and 1-bromo-3-phenyl propane are used as raw materials, and are prepared into a mixture of tetrabutyl ammonium bromide and K 2 CO 3 In the presence of (2) to obtain [ TMDPG ]] + Br - The method comprises the steps of carrying out a first treatment on the surface of the The [ TMDPG ]] + Br - And KPF (Key performance) 6 J, carrying out a displacement reaction to obtain hydrophobic ionic liquid; and combining the hydrophobic ionic liquid with nickel chloride to obtain the hydrophobic magnetic ionic liquid.
The polypropylene fiber source is a waste medical mask, and the preparation method of the polypropylene fiber comprises the following steps: sterilizing, melting, cooling and crushing the waste mask to obtain fiber base solution, preparing fiber tows through a spinning box, and finally shaping and drying to obtain the polypropylene fibers.
The bagasse ash used may comprise a powder having a particle size of 60 mesh to 110 mesh. The main component is silicon dioxide.
Examples 1 to 4
The following embodiments are four embodiments of the expansive soil improvement method according to the present invention, including the following steps:
free expansion ratio measurement
According to the geotechnical test method standard (GB/T50123-2019), the free expansion rate of the undisturbed expansive soil sample is measured to be 54.3%. The free expansion rate of the modified expansive soil after complete curing was also measured by a similar method.
Compaction test
According to the geotechnical test method Standard (GB/T50123-2019), the optimal water content of the undisturbed expansive soil is 15.7% by a compaction test.
Shear strength measurement
According to the geotechnical test method standard (GB/T50123-2019), the shearing stress of the undisturbed expansive soil under the vertical pressure of 30, 50, 70 and 90kPa is measured, and the shearing strength index c (cohesive force) =190.1 and phi (internal friction angle) =34.5 of the undisturbed expansive soil is obtained by analyzing the data. The shear strength index of the improved expansive soil is also measured by a similar test.
If the swelling grade of the swelling soil is III grade, an improvement mode of spraying the swelling soil modifier is used. According to the formulation shown in table 1, the expansive soil modifier was prepared by thoroughly stirring each raw material component. Then spraying the obtained expansive soil modifier on the surface layer of expansive soil
TABLE 1 formulation of expansive soil modifier of examples 1-4 expressed in weight fraction
TABLE 2 improvement of the expansive soil with the expansive soil improvers of examples 1 to 4 and performance index of the expansive soil after the improvement
As shown in the experimental results of Table 2, the free expansion rate of the expansive soil after being improved by spraying the expansive soil modifier is 22.8% -28.2%, which is reduced by 48% -58% compared with the free expansion rate of the original expansive soil, thereby reaching the requirement that the free expansion rate required by construction is not more than 40%, and simultaneously remarkably improving the shearing strength of the expansive soil.
Examples 5 to 8
The following embodiments are further four embodiments of the expansive soil improvement method of the present invention, comprising the steps of:
if the swelling grade of the swelling soil is grade II, an improved way of laying the surface improvement layer is used. According to the formulation shown in table 3 below, an expansive soil modifier slurry was prepared by sufficiently stirring the raw material components, and then uniformly mixing the expansive soil modifier slurry with expansive soil to be modified to obtain modified expansive soil, and then laying a surface modification layer.
TABLE 3 formulation of modified expansive soil of examples 5-8 expressed in weight fraction
| Examples | Example 5 | Example 6 | Example 7 | Example 8 |
| Polypropylene fiber | 0.5 | 1 | 0.5 | 1.0 |
| Bagasse ash | 85.5 | 90 | 90.5 | 85 |
| Hydrophobic magnetic ionic liquid | 14 | 9 | 9 | 14 |
TABLE 4 Performance index of the modified expansive soil with the modifier of examples 5 to 8
From the experimental results in table 4, it is apparent that the free expansion rate of the expansive soil after being improved by the improvement method of the paving surface improvement layer of the present invention is 28.1% -33%, which is reduced by 39% -58% compared with the free expansion rate of the original expansive soil, and the free expansion rate required by construction is not more than 40%, and at the same time, the shearing strength of the expansive soil is remarkably improved.
Example 9
The following embodiment is a further embodiment of the expansive soil improvement method according to the present invention, comprising the steps of:
if the swelling grade of the swelling soil is I grade, a method of paving a surface modifying layer and spraying a swelling soil modifying agent in a deep layer is used for modifying.
Based on 100 parts by weight of the polycarbonate resin-based suspension, the expansive soil modifier comprises the following components: 2 parts by weight of polyurethane adhesive and 30 parts by weight of hydrophobic magnetic ionic liquid. Fully stirring the raw material components to prepare the expansive soil modifier, and then spraying the expansive soil modifier on the surface layer of the expansive soil structure to be modified of the excavated soil body. The improved expansive soil comprises expansive soil modifier slurry and expansive soil to be improved. The expansive soil modifier slurry comprises the following components in percentage by weight: (a) 0.5 parts by weight of polypropylene fiber; (b) 90.5 parts by weight of bagasse ash; (c) 9 parts by weight of a hydrophobic magnetic ionic liquid. Fully stirring the raw material components to prepare expansive soil modifier slurry, and then according to the expansive soil modifier slurry: the expansive soil modifier slurry is uniformly mixed in a proportion of dry soil weight of the expansive soil to be modified=1/8-1/7, the expansive soil to be modified is modified to obtain the expansive soil, and a surface modification layer with the thickness of 40 cm is paved.
TABLE 6 Performance index of the modified expansive soil with the modifier of example 9
As is clear from the experimental results in Table 6, the free expansion rate of the expansive soil improved by the improved mode of spraying the expansive soil improver and paving the improved expansive soil layer is 27.1%, which is reduced by 72.9% compared with the free expansion rate of the original expansive soil, reaches the specification that the free expansion rate required by construction is not more than 40%, and simultaneously remarkably improves the shearing strength of the expansive soil.
The embodiments described hereinabove are presented to facilitate the understanding and application of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications can be readily made to these embodiments and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Accordingly, the present invention is not limited to the embodiments herein, and those skilled in the art, based on the present disclosure, make improvements and modifications within the scope and spirit of the invention.
Claims (8)
1. An expansive soil modifier, characterized in that the expansive soil modifier comprises:
(a) A polycarbonate resin-based suspension;
(b) Hydrophobic magnetic ionic liquids;
the structural formula of the hydrophobic magnetic ionic liquid is shown as the following formula (I):
(c) A polyurethane adhesive;
the expansive soil modifier is prepared from the following components in parts by weight: 100 parts of polycarbonate resin-based suspension, 2-5 parts of polyurethane adhesive and 20-30 parts of hydrophobic magnetic ionic liquid.
2. The expansive soil modifier of claim 1, wherein the expansive soil modifier is prepared from the following components in parts by weight: 0.5-1 part of polypropylene fiber, 85-90.5 parts of bagasse ash and 9-14 parts of hydrophobic magnetic ionic liquid.
3. The method for improving a expansive soil improver according to claim 1, wherein (1) the free expansion and shrinkage ratio δ of expansive soil is first determined ef Dividing the swelling grade of the swelling soil; (2) Then, different improvement modes are selected according to the expansion and contraction grade,
the grade of the expansion and shrinkage of the divided expansion soil is as follows:
(a) If delta is 40% or less ef If the expansion and shrinkage grade is less than or equal to 60 percent, selecting an improvement mode of spraying the expansive soil modifier;
(b) If 60% is less than or equal to delta ef If the expansion and contraction grade is less than or equal to 75 percent, selecting an improvement mode of paving a surface improvement layer;
(c) If 75% is less than or equal to delta ef If the expansion and shrinkage grade is less than or equal to 90 percent, the improvement mode of paving the surface improvement layer and spraying the expansive soil modifier in a combined deep layer is selected.
4. The expansive soil improvement method according to claim 3, characterized in that,
1) If the swelling grade of the swelling soil is III grade, the swelling soil improvement step of spraying the swelling soil modifier is as follows:
(a) Mixing polycarbonate resin-based suspension, hydrophobic magnetic ionic liquid and polyurethane adhesive according to a required proportion to obtain an expansive soil modifier;
(b) Uniformly spraying the expansive soil modifier obtained in the step (a) on the surface of soil to be modified;
2) If the swelling grade of the swelling soil is grade II, the swelling soil improvement step of selecting and paving the surface improvement layer is as follows:
(a) Digging out a part of the expansive soil body to be improved on the surface layer of the expansive soil structure to be improved;
(b) Determining the optimal water content of the expansive soil according to the compaction test;
(c) Uniformly mixing (a) polypropylene fibers in a desired ratio; (b) bagasse ash; (c) Hydrophobic magnetic ionic liquid to obtain expansive soil modifier slurry;
(d) Uniformly mixing the expansive soil modifier slurry prepared in the step (c) with expansive soil to be modified, wherein the mixing ratio of the expansive soil modifier slurry to the weight of the expansive soil to be modified is 1/8-1/7;
(e) Adding water into the uniformly mixed expansive soil modifier slurry obtained in the step (d) and the expansive soil to be modified according to the optimal water content obtained in the step (b), and uniformly stirring to obtain modified expansive soil;
(f) Paving a surface modification layer of 30 cm-50 cm on the construction surface of the modified expansive soil obtained in the step (d), and then keeping the surface modification layer for 3-4 days under natural conditions;
3) If the swelling grade of the swelling soil is grade I, the swelling soil improvement step of paving a surface improvement layer and spraying a swelling soil modifier in a combined deep layer is selected as follows:
(a) Digging out a part of the expansive soil body to be improved on the surface layer of the expansive soil structure to be improved;
(b) Determining the optimal water content of the expansive soil according to the compaction test;
(c) Mixing polycarbonate resin-based suspension, hydrophobic magnetic ionic liquid and polyurethane adhesive according to a required proportion to obtain an expansive soil modifier;
(d) Uniformly spraying the expansive soil modifier obtained in the step (c) on the surface of the structure from which the surface soil body is excavated;
(e) Repeating the step (d) for 3-5 times to ensure that the total amount of the sprayed expansive soil modifier is 1.2-1.6 kg/square meter expansive soil;
(f) Uniformly mixing polypropylene fiber, bagasse ash and hydrophobic magnetic ionic liquid according to a required proportion to obtain expansive soil modifier slurry;
(g) Uniformly mixing the expansive soil modifier slurry prepared in the step (f) with expansive soil to be modified, wherein the mixing ratio of the expansive soil modifier slurry to the weight of the expansive soil to be modified is 1/8-1/7;
(h) Adding water into the uniformly mixed expansive soil modifier slurry obtained in the step (g) and the expansive soil to be modified according to the optimal water content obtained in the step (c), and uniformly stirring to obtain modified expansive soil;
(i) And (3) paving a surface modification layer of 30 cm-50 cm on the construction surface of the modified expansive soil obtained in the step (h), and then keeping the surface modification layer for 3-4 days under natural conditions.
5. The expansive soil improvement method according to claim 4, wherein said surface improvement layer of step 2) is laid from an improved expansive soil comprising (a) an expansive soil modifier slurry; (b) The expansive soil is to be improved, and the slurry of the expansive soil modifier is prepared from the following components in parts by weight:
(a) Polypropylene fibers; 0.5-1 part of polypropylene fiber,
(b) Hydrophobic magnetic ionic liquids; 9-14 parts of hydrophobic magnetic ionic liquid,
(c) Bagasse ash: 85-90.5 parts of bagasse ash.
6. The expansive soil improvement method according to claim 4, wherein said bagasse ash is waste bagasse combustion products having a particle size of 60 mesh to 110 mesh.
7. The expansive soil improvement method according to claim 4, wherein said polypropylene fiber is produced by sterilizing, melting, cooling and crushing a waste medical mask to obtain a fiber base solution, producing a fiber tow by a spinning box, and finally shaping and drying to obtain a polypropylene fiber; the polypropylene fiber is regenerated fiber with the diameter of 1mm and the length of 10-20 mm.
8. The expansive soil modifier and the modifying method according to claims 1-7 are applied to slope engineering.
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