A saline soil-based insulation layer material and preparation method thereof

Abstract

The present invention relates to the technical field of saline soil pavement protection, and in particular to a saline soil-based barrier layer material and a preparation method thereof. The present application discloses a saline soil-based barrier layer material, comprising the following raw materials in parts by weight: 60 parts of saline soil, 40‑50 parts of Portland cement, 30‑40 parts of lime, 15‑25 parts of lignin, 5‑10 parts of inorganic silicon hybrid gel, 1‑3 parts of alginate, and 1‑3 parts of chitosan. The present application provides a saline soil-based barrier layer material, which converts the saline soil into a roadbed barrier layer material with excellent salt isolation performance by using the saline soil itself locally, thereby solving the problems of high construction costs and secondary salinization risks in traditional methods, and providing an economical, environmentally friendly and efficient solution for road construction in saline soil areas.

Description

Technical Field

[0001] The invention relates to the technical field of saline soil road surface protection, and in particular to a saline soil-based insulation layer material and a preparation method thereof. Background Art

[0002] Saline soil is a general term for saline soil, alkaline soil and various salinized and alkaline soils. Saline soil refers to soil in which the soluble salt content reaches a level that is significantly harmful to crop growth; alkaline soil refers to soil that contains a large amount of exchangeable sodium that is harmful to plant growth and changes the properties of the soil. The main types of damage to saline soil are dissolution damage, salt swelling damage, corrosion damage, slurry damage, moisture absorption and softening, and secondary salinization. In the face of these problems, if reasonable measures are not taken, it will seriously affect the structural stability of the roadbed, and then affect the durability and performance of the road surface. In severe cases, it will cause damage to the integrity of the road, causing huge losses of life and property.

[0003] At present, saline soil cannot be directly used as fill soil for roadbed construction; the treatment measures for saline soil are mainly to remove the saline soil, replace it with non-saline soil, and use composite geotextiles as a barrier layer for joint treatment in medium and strong saline soil areas. The amount of earthwork required in the entire process of replacing non-saline soil is huge, and it is necessary to transport soil with better performance over long distances to fill the roadbed, which not only increases transportation costs and increases the cost of the project, but also increases the difficulty of on-site organization and management. At the same time, due to the high salt content of the local roadbed soil and the shallow burial of the groundwater level, the salt will continue to rise with the underground capillary water. As time goes by, the bottom roadbed fill soil will eventually gradually become saline soil, which will cause dissolution, salt swelling, corrosion and other damage. The soil layer that has been replaced still has the problem of secondary salinization in the saline soil environment.

[0004] Therefore, it is necessary to carry out relevant research on the improvement and utilization of saline soil and the salt barrier of roadbed soil. Under the premise of ensuring the long-term performance of the roadbed, the saline soil along the highway can be utilized and turned into treasure, avoiding the high construction cost of the replacement method. Therefore, this application provides a saline soil base barrier layer material and a preparation method thereof. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the present invention provides a saline soil base barrier layer material and a preparation method thereof. By using the saline soil itself, the saline soil is converted into a roadbed barrier layer material with excellent salt isolation performance, thereby solving the problems of high construction costs and secondary salinization risks existing in traditional methods, and providing an economical, environmentally friendly and efficient solution for road construction in saline soil areas.

[0006] The first object of the present application is to provide a saline soil-based insulation layer material, comprising the following raw materials in parts by weight:

[0007] 60 parts of saline soil, 40-50 parts of Portland cement, 30-40 parts of lime, 15-25 parts of lignin, 5-10 parts of inorganic silicon hybrid gel, 1-3 parts of alginate and 1-3 parts of chitosan.

[0008] Preferably, the method for preparing the inorganic silicon hybrid gel comprises the following steps:

[0009] Acrylic acid is neutralized with alkali solution and sodium silicate solution to a neutralization degree of 65 mol% to obtain a neutralized solution; the neutralized solution is stirred at room temperature for 24 hours, N, N'-methylenebisacrylamide and ammonium persulfate are added respectively, stirred evenly, and allowed to stand at room temperature for 24 hours; then the temperature is raised to 50°C for reaction for 3 hours; after the reaction is completed, the inorganic silicon hybrid gel is obtained after washing, dehydration and drying.

[0010] More preferably, the alkali solution is sodium hydroxide solution.

[0011] More preferably, the added amounts of N,N′-methylenebisacrylamide and ammonium persulfate are 0.03 wt % and 2.5 wt % respectively, relative to the weight of acrylic acid.

[0012] Preferably, the salt content of the saline soil is ≥ 0.3%.

[0013] Preferably, the alginate is sodium alginate.

[0014] The second object of the present application is to provide a method for preparing the saline soil-based insulation layer material, comprising the following steps:

[0015] S1. Prepare materials according to the raw material composition of the saline soil-based insulation layer material, wherein the saline soil is collected in situ at the pre-construction site or near the pre-construction site; grind and sieve the collected saline soil, lignin, inorganic silicon hybrid gel, alginate, and chitosan respectively; and then fully mix them with silicate cement and lime to obtain a mixture;

[0016] S2. The mixture and water are fully mixed to obtain a slurry;

[0017] S3. Spread the slurry on the road surface, compact and maintain it, and obtain a saline soil-based barrier layer material.

[0018] Preferably, in step S1, the sieving is through a 10-mesh sieve.

[0019] Preferably, in step S2, the amount of water added is 0.5-0.6 times the weight of the mixture.

[0020] Preferably, in step S3, the maintenance is to carry out roadbed maintenance at room temperature for 7 days. During the maintenance process, watering is carried out appropriately to maintain the relative humidity at 30-40%.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The saline soil-based barrier layer material of the present invention is mainly composed of a variety of raw materials such as saline soil, silicate cement, lime, lignin, inorganic silicon hybrid gel, alginate and chitosan mixed in a specific proportion. By using the saline soil itself, the saline soil is converted into a roadbed barrier layer material with excellent salt isolation performance, which solves the problems of high construction cost and secondary salinization risk in traditional methods, and provides an economical, environmentally friendly and efficient solution for road construction in saline soil areas.

[0023] 2. The barrier layer material of the present invention has high unconfined compressive strength, as well as low porosity, 90-day water permeability coefficient and 90-day expansion rate, and can significantly improve the overall stability and durability of the roadbed. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0025] Figure 1 This is a process flow chart of a method for preparing a saline soil-based insulation layer material described in this application. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments, and the contents mentioned in the implementation modes are not intended to limit the present invention.

[0027] As used herein, "and / or" includes the term of all combinations of any one or more associated listed items. The terms used herein are only used to describe specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "a", "an", "an" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It is further understood that "including", when used in this specification, specifies the stated features, integers, steps, operations, elements and / or compositions, but does not exclude the existence or addition of one or more other features, integers, steps, operations, elements, compositions and / or combinations thereof.

[0028] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. It is further understood that terms, such as defined in commonly used dictionaries, are interpreted in accordance with their meanings in the context of the relevant art and are not in an idealized or overly formal sense unless explicitly so defined herein.

[0029] The exemplary invention described herein may appropriately lack any one or more element limitations that are not specifically disclosed herein. Therefore, the terms "comprise", "include", "contain", etc. should be understood broadly and non-restrictively. In addition, the terminology used herein is used as a description, not a limitation, and it is unintentional to use these terminology expressions that do not include any equivalent characteristics, but only describe some of their characteristics, but various modifications are possible within the scope of the present invention according to the rights. Therefore, although the present invention has been specifically disclosed by preferred embodiments and optional features, the modifications disclosed herein to embody the changes of the present invention may be recorded by those skilled in the art, and such modifications and changes will be considered to be within the scope of the present invention.

[0030] A saline soil-based insulation layer material, comprising the following raw materials in parts by weight:

[0031] 60 parts of saline soil, 40-50 parts of Portland cement, 30-40 parts of lime, 15-25 parts of lignin, 5-10 parts of inorganic silicon hybrid gel, 1-3 parts of alginate and 1-3 parts of chitosan.

[0032] Specifically, the preparation method of the inorganic silicon hybrid gel comprises the following steps:

[0033] In an ice-water bath, acrylic acid (AA) is neutralized to a neutralization degree of 65 mol% (SS:AA=0.3:1) using a sodium hydroxide solution and a sodium silicate (SS) solution with a mass solubility of 20% to obtain a neutralized solution; the neutralized solution is stirred at room temperature for 24 hours, and N,N′-methylenebisacrylamide and ammonium persulfate are added (the amount of N,N′-methylenebisacrylamide and ammonium persulfate added is 0.03wt% and 2.5wt% relative to the weight of acrylic acid), respectively, stirred evenly, and allowed to stand at room temperature for 24 hours; then the temperature is raised to 50°C for reaction for 3 hours; after the reaction is completed, the product is soaked in water, washed, and dehydrated with anhydrous ethanol, and the product after dehydration with anhydrous ethanol is dried at 80°C to constant weight to obtain an inorganic silicon hybrid gel.

[0034] Therefore, a nano-hybrid core-shell hydrogel is obtained by using water-soluble sodium silicate as a silicon source, the sol-gel method and the cross-linking polymerization of acrylic acid, wherein SiO2 is the core and cross-linked polyacrylic acid is the shell; the inorganic silicon hybrid gel has good mechanical strength after swelling and has good salt resistance. The inorganic silicon hybrid gel is applied to saline soil. The inorganic silicon hybrid gel has a strong cementing ability and is easy to fill in the pores to achieve the effect of connecting soil particles or aggregates, so it can significantly improve the strength and salt resistance of the soil.

[0035] In the present application, the weight proportion of the inorganic silicon hybrid gel is 5-10 parts, and specifically can be any value among 5 parts, 6 parts, 7 parts, 8 parts, and 10 parts, as long as it meets the requirement of 5-10 parts.

[0036] Specifically, the salt content of the saline soil is ≥ 0.3% (by weight), preferably 3-10%. The saline soil is collected in situ from the saline soil body or collected from the nearby saline soil body. The salt content in the soil is determined according to the method disclosed in LY / T1251-199; "saline soil" refers to the general term for saline soil and alkaline soil as well as various salinized and alkaline soils. In my country, saline soil is mainly distributed in inland arid, semi-arid areas and coastal areas. The present invention does not particularly limit the source of the saline soil, and it can be collected from areas where saline soil is mainly distributed in my country.

[0037] More specifically, the saline soil may be at least one of chloride saline soil, sulfate saline soil, carbonate saline soil, subchloride saline soil and sulfite saline soil.

[0038] Specifically, the weight of silicate cement is 40-50 parts, and can be any value among 40 parts, 45 parts, 46 parts, 47 parts, 48 ​​parts, and 50 parts, as long as it meets the requirement of 40-50 parts. Specifically, in the present application, after the silicate cement is solidified, it mainly plays the role of enhancing the strength of the material; in addition, the silicate cement also has certain impermeability and salt erosion resistance, which helps to prevent the erosion and damage of the insulation layer material by salt.

[0039] Specifically, the weight of lime is 30-40 parts, and can be any value among 30 parts, 35 parts, 36 parts, 37 parts, 38 parts, and 40 parts, as long as it meets the requirement of 30-40 parts. The main component of lime is calcium oxide. Lime digestion reaction produces Ca 2+ Ion exchange occurs with positive monovalent cations. Therefore, in this application, by adding lime, the thickness of the double electric layer of the soil particles of saline soil can be reduced, so that the soil particles are closer to each other, thereby improving the strength of the soil. However, if the soil of saline soil is solidified by lime alone, it is easy to cause cracking and brittle failure, especially for chloride saline soil, whose initial strength and water stability are poor after lime solidification.

[0040] Specifically, the weight of lignin is 15-25 parts, and can be any value among 15 parts, 16 parts, 17 parts, 18 parts, 20 parts, and 25 parts, as long as it meets the requirement of 15-25 parts. Calcium lignin sulfonate is a brown-yellow powder with strong water solubility; in the present application, after calcium lignin sulfonate is added to saline soil, the soil particles are completely wrapped by the calcium lignin sulfonate powder. Since calcium lignin sulfonate itself has adhesiveness, the particles of the saline soil are connected as a whole, the internal structure of the soil is compact, and the macroscopically exhibits better mechanical properties.

[0041] Specifically, the alginate is sodium alginate, and the weight portion of the alginate is 1-3 parts, and specifically can be any value among 1 part, 2 parts, and 3 parts, as long as it meets the requirement of 1-3 parts. In the present application, the role of alginate in the saline soil-based insulation layer material is mainly reflected in its excellent water retention and adhesion. It can effectively absorb and retain moisture, increase the humidity stability of the material, and reduce shrinkage cracks caused by water evaporation.

[0042] Specifically, the weight of chitosan is 1-3 parts, and can be any value of 1 part, 2 parts, or 3 parts, as long as it meets the requirements of 1-3 parts. Chitosan, as a natural polymer material, has good biocompatibility and environmental friendliness. In the present application, chitosan also has certain salt resistance and water retention, which helps to reduce the negative impact of salt on the insulation layer material.

[0043] like Figure 1 As shown, the preparation method of the saline soil-based insulation layer material comprises the following steps:

[0044] S1. The saline soil is collected in situ at the pre-construction site or near the pre-construction site. The collected saline soil, lignin, inorganic silicon hybrid gel, alginate, and chitosan are crushed and sieved (through a 10-mesh sieve); according to the raw material composition of the saline soil-based insulation layer material, the crushed and sieved saline soil, the crushed and sieved lignin, the crushed and sieved inorganic silicon hybrid gel, the crushed and sieved alginate, the crushed and sieved chitosan and silicate cement and lime are prepared and sampled according to the corresponding weight parts, and the raw materials are fully mixed to obtain a mixture;

[0045] S2. The mixture and water are thoroughly mixed, and the amount of water added is 0.5-0.6 times the weight of the mixture to obtain a slurry;

[0046] S3. The slurry is laid on the road surface, compacted and cured. The curing is to perform roadbed curing at room temperature for 7 days. During the curing process, water is sprinkled appropriately to maintain the relative humidity at 30-40%. After the curing is completed, a saline soil base insulation layer material is obtained.

[0047] Example 1

[0048] A saline soil-based insulation layer material, comprising the following raw materials in parts by weight:

[0049] 60 parts of saline soil (salt content 3%), 40 parts of Portland cement, 30 parts of lime, 15 parts of lignin, 5 parts of inorganic silicon hybrid gel, 1 part of sodium alginate and 1 part of chitosan.

[0050] The method for preparing the saline soil-based insulation layer material comprises the following steps:

[0051] S1. The saline soil is collected in situ at the pre-construction site or near the pre-construction site.

[0052] The collected saline soil, lignin, inorganic silicon hybrid gel, alginate, and chitosan are respectively crushed and sieved (through a 10-mesh sieve); according to the raw material composition of the saline soil-based insulation layer material, the crushed and sieved saline soil, the crushed and sieved lignin, the crushed and sieved inorganic silicon hybrid gel, the crushed and sieved alginate, the crushed and sieved chitosan and silicate cement and lime are prepared and sampled according to corresponding weight portions, and each raw material is fully mixed to obtain a mixture;

[0053] S2. The mixture and water are thoroughly mixed, and the amount of water added is 0.5 times the weight of the mixture to obtain a slurry;

[0054] S3. The slurry is laid on the road surface, compacted and cured. The curing is to perform roadbed curing at room temperature for 7 days. During the curing process, water is sprinkled appropriately to maintain the relative humidity at 30-40%. After the curing is completed, a saline soil base insulation layer material is obtained.

[0055] Example 2

[0056] A saline soil-based insulation layer material, comprising the following raw materials in parts by weight:

[0057] 60 parts of saline soil (salt content 5%), 50 parts of Portland cement, 40 parts of lime, 25 parts of lignin, 10 parts of inorganic silicon hybrid gel, 3 parts of sodium alginate and 3 parts of chitosan.

[0058] The method for preparing the saline soil-based insulation layer material comprises the following steps:

[0059] S1. The saline soil is collected in situ at the pre-construction site or near the pre-construction site.

[0060] The collected saline soil, lignin, inorganic silicon hybrid gel, alginate, and chitosan are respectively crushed and sieved (through a 10-mesh sieve); according to the raw material composition of the saline soil-based insulation layer material, the crushed and sieved saline soil, the crushed and sieved lignin, the crushed and sieved inorganic silicon hybrid gel, the crushed and sieved alginate, the crushed and sieved chitosan and silicate cement and lime are prepared and sampled according to corresponding weight portions, and each raw material is fully mixed to obtain a mixture;

[0061] S2. The mixture and water are thoroughly mixed, and the amount of water added is 0.6 times the weight of the mixture to obtain a slurry;

[0062] S3. The slurry is laid on the road surface, compacted and cured. The curing is to perform roadbed curing at room temperature for 7 days. During the curing process, water is sprinkled appropriately to maintain the relative humidity at 30-40%. After the curing is completed, a saline soil base insulation layer material is obtained.

[0063] Example 3

[0064] A saline soil-based insulation layer material, comprising the following raw materials in parts by weight:

[0065] 60 parts of saline soil (salt content 10%), 45 parts of silicate cement, 35 parts of lime, 20 parts of lignin, 8 parts of inorganic silicon hybrid gel, 2 parts of sodium alginate and 2 parts of chitosan.

[0066] The method for preparing the saline soil-based insulation layer material comprises the following steps:

[0067] S1. The saline soil is collected in situ at the pre-construction site or near the pre-construction site.

[0068] The collected saline soil, lignin, inorganic silicon hybrid gel, alginate, and chitosan are respectively crushed and sieved (through a 10-mesh sieve); according to the raw material composition of the saline soil-based insulation layer material, the crushed and sieved saline soil, the crushed and sieved lignin, the crushed and sieved inorganic silicon hybrid gel, the crushed and sieved alginate, the crushed and sieved chitosan and silicate cement and lime are prepared and sampled according to corresponding weight portions, and each raw material is fully mixed to obtain a mixture;

[0069] S2. The mixture and water are thoroughly mixed, and the amount of water added is 0.55 times the weight of the mixture to obtain a slurry;

[0070] S3. The slurry is laid on the road surface, compacted and cured. The curing is to perform roadbed curing at room temperature for 7 days. During the curing process, water is sprinkled appropriately to maintain the relative humidity at 30-40%. After the curing is completed, a saline soil base insulation layer material is obtained.

[0071] Comparative Example 1

[0072] A saline soil-based insulation layer material, comprising the following raw materials in parts by weight:

[0073] 60 parts of saline soil, 40 parts of Portland cement, and 30 parts of lime.

[0074] The remaining conditions are the same as those in Example 1.

[0075] Comparative Example 2

[0076] A saline soil-based insulation layer material, comprising the following raw materials in parts by weight:

[0077] 60 parts of saline soil, 40 parts of Portland cement, 30 parts of lime, and 15 parts of lignin.

[0078] The remaining conditions are the same as those in Example 1.

[0079] Comparative Example 3

[0080] A saline soil-based insulation layer material, comprising the following raw materials in parts by weight:

[0081] 60 parts of saline soil, 40 parts of Portland cement, 30 parts of lime, 15 parts of lignin, 1 part of sodium alginate, and 1 part of chitosan. The other conditions are the same as those in Example 1.

[0082] Comparative Example 4

[0083] A saline soil-based insulation layer material, comprising the following raw materials in parts by weight:

[0084] 60 parts of saline soil, 40 parts of Portland cement, 30 parts of lime, 15 parts of lignin, and 5 parts of inorganic silicon hybrid gel. The other conditions are the same as those in Example 1.

[0085] Among them, the inorganic silicon hybrid gel involved in the embodiment or the comparative example is prepared as follows: under ice-water bath conditions (0-5°C), acrylic acid (AA) is neutralized to a neutralization degree of 65 mol% (SS:AA=0.3:1) using a sodium hydroxide solution and a sodium silicate (SS) solution with a mass solubility of 20% to obtain a neutralized solution; the neutralized solution is stirred at room temperature for 24 hours, N,N′-methylenebisacrylamide and ammonium persulfate are added respectively (the amount of N,N′-methylenebisacrylamide and ammonium persulfate added is 0.03wt% and 2.5wt% relative to the weight of acrylic acid), stirred evenly, and allowed to stand at room temperature for 24 hours; then the temperature is raised to 50°C for reaction for 3 hours; after the reaction is completed, the product is soaked in water, washed, and dehydrated with anhydrous ethanol, and the product after dehydration with anhydrous ethanol is dried at 80°C to constant weight to obtain an inorganic silicon hybrid gel.

[0086] In the embodiments or comparative examples, the compacted thickness is controlled at 95-100 mm.

[0087] The saline soil-based insulation layer materials prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to the following performance tests, and the test results are summarized in Table 1.

[0088] 1. Unconfined compressive strength shall be measured in accordance with the Railway Geotechnical Test Code TB10102-2010.

[0089] 2. Porosity, 90-day water permeability coefficient, and 90-day expansion rate are measured according to the "Test Method for Long-term Performance and Durability of Ordinary Concrete" (GB / T50082-2009)

[0090] Table 1

[0091]

[0092] From the test results of Examples 1-3 and Comparative Examples 1-4, it can be seen that the saline soil-based barrier layer material described in the present application has a higher unconfined compressive strength, as well as a lower porosity, 90-day water permeability coefficient and 90-day expansion rate, which can significantly improve the overall stability and durability of the roadbed.

[0093] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention may also be implemented in other ways. Any obvious replacement without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. A saline soil-based insulation layer material, characterized in that: The invention comprises the following raw materials in parts by weight: 60 parts of saline soil, 40-50 parts of Portland cement, 30-40 parts of lime, 15-25 parts of lignin, 5-10 parts of inorganic silicon hybrid gel, 1-3 parts of alginate, and 1-3 parts of chitosan; The preparation method of the inorganic silicon hybrid gel comprises the following steps: The acrylic acid is neutralized with an alkali solution and a sodium silicate solution to a neutralization degree of 65 mol % to obtain a neutralized solution; the neutralized solution is stirred at room temperature for 24 hours, N,N'-methylenebisacrylamide and ammonium persulfate are added respectively, stirred evenly, and allowed to stand at room temperature for 24 hours; then the temperature is raised to 50°C for reaction for 3 hours; after the reaction is completed, the inorganic silicon hybrid gel is obtained after washing, dehydration and drying; The alkali solution is a sodium hydroxide solution; The added amounts of N,N'-methylenebisacrylamide and ammonium persulfate are 0.03 wt % and 2.5 wt % respectively, relative to the weight of acrylic acid.

2. The saline soil-based insulation layer material according to claim 1, characterized in that: The salt content of the saline soil is ≥0.3%.

3. The saline soil-based insulation layer material according to claim 1, characterized in that: The alginate is sodium alginate.

4. The method for preparing the saline soil-based insulating layer material according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Prepare materials according to the raw material composition of the saline soil-based insulation layer material, wherein the saline soil is collected in situ at the pre-construction site or near the pre-construction site; grind and sieve the collected saline soil, lignin, inorganic silicon hybrid gel, alginate, and chitosan respectively; and then fully mix them with silicate cement and lime to obtain a mixture; S2. The mixture and water are fully mixed to obtain a slurry; S3. Spread the slurry on the road surface, compact and maintain it, and obtain a saline soil-based barrier layer material.

5. The preparation method according to claim 4, characterized in that: In step S1, the sieving is performed through a 10-mesh sieve.

6. The preparation method according to claim 4, characterized in that: In step S2, the amount of water added is 0.5-0.6 times the weight of the mixture.

7. The preparation method according to claim 4, characterized in that: In step S3, the curing is to perform roadbed curing at room temperature for 7 days.

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