CN115557766A - Roadbed filler and preparation method thereof - Google Patents
Roadbed filler and preparation method thereof Download PDFInfo
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- CN115557766A CN115557766A CN202211140942.0A CN202211140942A CN115557766A CN 115557766 A CN115557766 A CN 115557766A CN 202211140942 A CN202211140942 A CN 202211140942A CN 115557766 A CN115557766 A CN 115557766A
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/10—Lime cements or magnesium oxide cements
- C04B28/12—Hydraulic lime
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0035—Processes characterised by the absence of a mechanical mixing step, e.g. "no-mix" processes
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/0075—Uses not provided for elsewhere in C04B2111/00 for road construction
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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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Abstract
The invention provides a roadbed filling material and a preparation method thereof, and belongs to the technical field of roadbeds. Mixing and ball-milling the fly ash and the hydrated lime to a nanometer level, performing polydopamine modification treatment, mixing and reacting with loess, acidifying the obtained modified loess, further reacting with an anionic surfactant to perform hydrophobization treatment, mixing the obtained hydrophobization loess with a sulfate solution, drying, and performing dynamic compaction and compaction to obtain the roadbed filler. The roadbed filler prepared by the invention has the advantages of good mechanical property, high strength, almost no seismic subsidence, almost complete elimination of liquefaction potential of the foundation soil, modification of low-cost loess into roadbed filler with high additional value, simple preparation method, mild reaction conditions, wide application range of the prepared roadbed filler and wide application prospect.
Description
Technical Field
The invention relates to the technical field of roadbeds, in particular to a roadbed filling material and a preparation method thereof.
Background
The roadbed is used as an important component of the whole transportation system, directly bears the long-term action of superstructure load and vehicle static and dynamic load, and the quality of the roadbed directly influences the driving speed and the driving safety, so that high-quality roadbed filling materials are required to be adopted for filling. However, the expansive soil for the poor roadbed filling is widely distributed, has obvious dilatancy, hyperconjugation and multi-fracture, and brings considerable harm to roadbed construction. When the expansive soil field is used for road and roadbed construction, the filler of the natural field does not meet the basic requirements of high-grade highway and railway roadbed filling.
The middle-jiao region is distributed with a large amount of self-weight collapsible loess which is loose and porous, has low strength and weak bearing capacity, and the technical indexes of the loess can not meet the use requirements of roadbed fillers. Therefore, the loess can be treated by adopting a chemical improvement mode so as to improve the strength of the loess, enhance the stability, reduce and prevent roadbed diseases and ensure the safe operation of roads. The middle-jiao region belongs to temperate zone continental climate, the temperature is reduced in winter, the road foundation soil body is cold and dry, the road foundation soil body can be influenced by frost heaving and freeze thawing action under the change of the external temperature, and the technical property of the roadbed filling is inevitably changed, so that the strength and the stability of the roadbed are influenced. Therefore, the research on the chemical improvement of the freezing resistance of the loess has great practical significance by combining the natural environment of the on-site roadbed.
The relation between the frost heaving ratio and the freezing and thawing times of the modified soil with different polystyrene foam (EPS) particle mixing amounts is established by Zhang Dong et al. Horse ice research finds that the content of lime-modified saline soil particles is obviously increased and the liquid-plastic limit is slightly reduced under the condition of freeze-thaw cycle. Zhang Shuling and the like research the influence factors of the uniaxial compressive strength of the cement soil and the fly ash soil after the freeze-thaw cycling action, and obtain the conclusion that the freeze resistance of the fly ash soil is better. The changes of the mechanical properties of the cement under the action of freeze-thaw cycles are researched by Pongwentai and the like and Chensili and the like. Researches on Lixianzi and Lvqingfeng and the like find that the frost heaving rate of a soil body can be reduced and the freezing resistance can be improved after modifiers such as lime, cement and the like are added into loess.
Therefore, the strength and stability of the roadbed soil structure are closely related to the natural environment (climate temperature, hydrological conditions and the like) of the site. At present, the actual temperature and humidity of a roadbed soil body on site are less considered in the selection and design of roadbed fillers, so that the roadbed is unevenly settled under the freezing and thawing action, and a road structure is damaged. In addition, the moisture content is one of important factors influencing the frost resistance of the roadbed, the moisture content of the roadbed in construction is deviated from the optimal moisture content in a room, and the roadbed soil body is easy to generate frost heaving in different degrees for a cold shut-in area in winter.
The micro-structure test result of natural loess shows that flocculent cemented substance exists between the loess particles, the particles are in mosaic distribution, the mosaic particles are mainly in point contact, the overhead pores are very obvious, and the overhead pores are the main reasons for causing poor engineering characteristics such as high compressibility, collapsibility and low strength of the loess.
Disclosure of Invention
The invention aims to provide a roadbed filler and a preparation method thereof, the prepared roadbed filler has good mechanical property, high strength and almost no seismic subsidence, can almost completely eliminate the liquefaction potential of foundation soil, modifies low-cost loess into high-additional-value roadbed filler, and has the advantages of simple preparation method, mild reaction conditions, wide application range of the prepared roadbed filler and wide application prospect.
The technical scheme of the invention is realized as follows:
the invention provides a preparation method of roadbed filler, which comprises the steps of mixing fly ash and hydrated lime, carrying out ball milling to a nanometer level, carrying out polydopamine modification treatment, carrying out mixing reaction with loess, acidifying the obtained modified loess, further carrying out reaction with an anionic surfactant for carrying out hydrophobization treatment, mixing the obtained hydrophobization loess with a sulfate solution, drying, and further carrying out dynamic compaction and compaction to obtain the roadbed filler.
As a further improvement of the invention, the method comprises the following steps:
s1, preparing a mixed modified material: uniformly mixing the fly ash and the hydrated lime to obtain a material, and performing ball milling to obtain a mixed modified material;
s2, preparing a polydopamine modified material: dispersing the mixed modified material prepared in the step S1 in water, adding dopamine hydrochloride and a catalyst, heating for reaction, centrifuging, washing and drying to obtain a polydopamine modified material;
s3, preparing modified loess: dispersing loess in water, adding the polydopamine modified material prepared in the step S2, uniformly mixing, heating for reaction, filtering, and drying to obtain modified loess;
s4, acidizing: adding the modified loess prepared in the step S3 into acid liquor for soaking, filtering and washing to obtain acidified modified loess;
s5, hydrophobization treatment: dispersing the acidified modified loess prepared in the step S4 in water, adding an anionic surfactant, uniformly mixing, and heating for reaction to obtain hydrophobized modified loess;
s6, mixing treatment: dispersing the hydrophobized modified loess prepared in the step S5 in water, adding sulfate, stirring and mixing uniformly, evaporating to remove the solvent, and drying to obtain a mixture;
s7, dynamic compaction and compaction treatment: and (5) performing dynamic compaction and compaction treatment on the mixture prepared in the step (S6) under a certain pressure to prepare the roadbed filling.
As a further improvement of the invention, the mass ratio of the fly ash to the hydrated lime in the step S1 is 7-12; the ball milling conditions are that agate balls are used as milling balls, ethanol is used as a ball milling medium, and the mass ratio of the materials: agate ball: respectively weighing the materials, the agate balls and the ethanol according to the mass ratio of 1; the mass ratio of the mixed modified material, the dopamine hydrochloride and the catalyst in the step S2 is 20-30; the catalyst is a Tris-HCl solution with 3-5wt% of cobalt salt and pH = 6.5-6.7; the heating reaction is carried out at the temperature of 40-50 ℃ for 2-4h.
Further, the cobalt salt is selected from at least one of cobalt chloride and cobalt sulfate.
As a further improvement of the invention, the mass ratio of the loess and the polydopamine modified material in the step S3 is 10-15; the heating reaction is carried out at the temperature of 35-45 ℃ for 1-3h; the acid solution in the step S4 is 1-3mol/L hydrochloric acid or sulfuric acid solution; the soaking time is 30-50min; the solid-liquid ratio of the modified loess to the acid liquid is 1-5 g/mL.
As a further improvement of the present invention, in step S5, the anionic surfactant is at least one selected from sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium dodecyl sulfonate, sodium hexadecyl benzene sulfonate, sodium hexadecyl sulfate, sodium octadecyl benzene sulfonate, and sodium octadecyl sulfate; the mass ratio of the acidified modified loess to the anionic surfactant is 10-5; the temperature of the heating reaction is 30-40 ℃, and the time is 0.5-1.5h.
As a further improvement of the invention, the anionic surfactant is a compound mixture of sodium stearyl sulfate and sodium stearyl sulfonate, and the mass ratio is 3-5.
The hydrophobic alkyl chain of sodium octadecyl sulfate and sodium octadecyl sulfonate is longer, and after hydrophobic modification, the long-chain alkyl chain has a better hydrophobic effect at the outer end, so that the capillary water absorption phenomenon inside the loess is greatly reduced, and the internal drying of the loess is favorably kept. Meanwhile, after the compound modification of the sodium octadecyl sulfate and the sodium octadecyl sulfonate, the prepared roadbed filling material has better low-temperature resistance, smaller frost heaving deformation and lower frost heaving rate.
As a further improvement of the present invention, the mass ratio of the hydrophobized modified loess and sulfate in step S6 is 100; the sulfate is selected from at least one of sodium sulfate, potassium sulfate and magnesium sulfate; in step S7, the pressure is 5-7MPa.
As a further improvement of the invention, the method specifically comprises the following steps:
s1, preparing a mixed modified material: mixing 7-12 parts by weight of fly ash and 2-5 parts by weight of slaked lime, stirring and mixing for 15-20min to obtain a material, and performing ball milling to obtain a mixed modified material;
the ball milling conditions are that agate balls are used as milling balls, ethanol is used as a ball milling medium, and the mass ratio of the materials: agate ball: respectively weighing the materials, the agate balls and the ethanol according to the mass ratio of 1;
s2, preparing a polydopamine modified material: dispersing 20-30 parts by weight of the mixed modified material prepared in the step S1 in water, adding 25-32 parts by weight of dopamine hydrochloride and 2-3 parts by weight of catalyst, heating to 40-50 ℃ for reaction for 2-4h, centrifuging, washing and drying to obtain a polydopamine modified material;
the catalyst is a Tris-HCl solution with 3-5wt% of cobalt salt and pH = 6.5-6.7;
s3, preparing modified loess: dispersing 10-15 parts by weight of loess in water, adding 5-7 parts by weight of polydopamine modified material obtained in the step S2, mixing under stirring for 10-15min, heating to 35-45 ℃, reacting under stirring for 1-3h, filtering, and drying to obtain modified loess;
s4, acidizing: adding the modified loess prepared in the step S3 into 1-3mol/L hydrochloric acid or sulfuric acid solution for soaking for 30-50min, wherein the solid-to-liquid ratio of the modified loess to the 1-3mol/L hydrochloric acid or sulfuric acid solution is 1-3 g/mL; filtering, and washing to obtain acidified modified loess;
s5, hydrophobization treatment: dispersing 10 parts by weight of the acidified modified loess obtained in the step S4 in water, adding 3-5 parts by weight of an anionic surfactant, stirring and mixing for 15-20min, heating to 30-40 ℃, and stirring to react for 0.5-1.5h to obtain hydrophobized modified loess;
the anionic surfactant is a compound mixture of sodium octadecyl sulfate and sodium octadecyl sulfonate, and the mass ratio is 3-5;
s6, mixing treatment: dispersing 100 parts by weight of the hydrophobized modified loess prepared in the step S5 in water, adding 3-5 parts by weight of sulfate, stirring and mixing for 15-20min, evaporating to remove the solvent, and drying to obtain a mixture;
s7, dynamic compaction and compaction treatment: and (5) performing dynamic compaction and compaction treatment on the mixture prepared in the step (S6) under the pressure of 5-7MPa to prepare the roadbed filling.
The invention further protects the roadbed filling prepared by the preparation method.
The invention further protects the application of the roadbed filling material in preparing the roadbed of the urban highway and the urban and rural highway.
The invention has the following beneficial effects:
the fly ash and the hydrated lime are ground to be nano-grade by ball milling to obtain a mixed modified material with very small granularity; the high valence metal ions in fly ash and slaked lime can replace univalent cations in loess, so that small particles form stable flocculent structure, such as Ca in fly ash and slaked lime 2+ Ion replacement of Na in soil + ，K + And the soil particles are attached to the surfaces of the particles to form aggregates, so that the stability of the soil body is effectively improved. The fly ash modified loess can achieve the aim of improving soil strength through hydration and flocculation in short-term reaction and silicification in long-term reaction, and the fly ash contains more active SiO 2 ，Al 2 O 3 ，Fe 2 O 3 When the content of CaO in the acidic oxides is lower, the self-cohesion is poorer, and under a certain water environment, the calcium hydroxide in the hydrated lime compounded with the acidic oxides reacts with the active oxides in the fly ash to crystallize, and gradually hydrate the glass bodyThe surface of the loess is infiltrated with silica gel and hydrated silicate centers, the silica gel and hydrated silicate centers exist in a soil framework form, and the formation of the crystal is irreversible, so that the soil strength of the loess is obviously improved. In addition, potassium ions and sodium ions adsorbed on the surface of the soil body clay are replaced by divalent calcium ions into clay which adsorbs divalent cations through the actions of water absorption reaction, ion exchange-water gel connection action, consolidation reaction, carbonic acid compound crystallization and the like of slaked lime, and calcium silicate compounds, calcium aluminate melilite hydrates and the like are generated, so that particles in the soil body form aggregates, and the strength of the soil body is improved. The reaction time of lime and loess can reach 8-10 years, so that the strength of the modified loess is gradually increased in the period, and the later strength growth trend is more obvious.
The mixed modified material comprises nano fly ash and nano hydrated lime, the nano fly ash and the nano hydrated lime further react with dopamine, a polydopamine layer is compounded on the surface of the mixed modified material, after the polydopamine modified material is mixed with loess, the polydopamine layer is rich in hydroxyl, amino and carboxyl structures, has extremely high viscosity, and can form hydrogen bonds with surface hydroxyl groups of the loess, the adhesion effect among granules in the loess is improved by adding the viscous polydopamine modified material, and the tiny viscous polydopamine modified material falls into overhead pores among the loess granules, so that a soil body tends to be more dense, the strength of the loess is improved, and the permeability of the loess is reduced. Through adding polydopamine modified material in the loess, change the contact condition of the inside granule of loess, reduce the inside pore volume of loess soil body, improved the characteristics of porous gap, weak cementation that exist in the loess structure for the loess is changeed closely knit, and the porosity is lower, thereby has greatly strengthened the intensity of loess, has improved its mechanical properties.
Further, the modified loess is added into the acid solution, so that the surface of the modified loess has a large number of positive electricity centers, and after the anionic surfactant is further added, the negative electricity centers of the anionic surfactant and the positive electricity centers of the surface of the modified loess are electrostatically attracted, and the long-chain alkyl chains of the anionic surfactant face to the opposite direction, so that the hydrophobic modification is realized. Because the inside capillary phenomenon that still exists of ordinary loess soil body, the shutoff is used in reducing the permeability, easily leads to inside moisture to be difficult to discharge rapidly, is unfavorable for maintaining the inside dry state of loess. Therefore, after the modified loess is subjected to hydrophobic modification, the surfaces of the internal capillaries are covered with hydrophobic alkyl chains, so that the phenomenon of capillary water absorption in the soil is greatly reduced, and the effect of keeping the soil dry is facilitated; has better low temperature resistance, smaller frost heaving deformation and low frost heaving rate.
Meanwhile, a small amount of sulfate is added, and in the presence of the fly ash, the sulfate is used as an exciting agent and can promote hydration reaction of active components in the fly ash, for example, hydrated calcium aluminate can further react with the sulfate to generate ettringite, so that the mechanical property of the loess is enhanced. After further dynamic compaction and compaction treatment, the compactness and the particle arrangement form of the prepared roadbed filling are changed, so that the mechanical property of the roadbed filling is obviously improved.
The invention takes the fly ash as one of the modifiers, can utilize the fly ash for the second time, not only can effectively reduce the cost of treating the building foundation, but also can fully utilize the building waste to achieve the effect of protecting the environment. Meanwhile, the roadbed filler prepared by the invention has the advantages of good mechanical property, high strength, almost no seismic subsidence, almost complete elimination of the liquefaction potential of the foundation soil, modification of low-cost loess into high-addition value roadbed filler, simple preparation method, mild reaction conditions, wide application range of the prepared roadbed filler and wide application prospect.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is an SEM image of the roadbed filler prepared in example 1.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The loess adopted by the embodiment of the invention is collected from Kyushu Taiwan of Lanzhou city, is light yellow, is loose and uniform in soil quality and has lower natural water content. The basic physical parameters are shown in Table 1.
TABLE 1
| Internal friction angle (°) | 3.7 |
| Liquid limit (%) | 23.7 |
| Plastic limit (%) | 15.9 |
| Water content (%) | 17.2 |
| Void ratio | 1.22 |
Fly ash with unburned carbon content of 3% -15%, mainly silicon dioxide (SiO) 2 ) And aluminum oxide (Al) 2 O 3 ) And a small amount of iron (Fe) trioxide 2 O 3 ) Calcium oxide (CaO), magnesium oxide (MgO), oxideSodium (Na) 2 O), potassium oxide (K) 2 O) and Sulfur Oxide (SO) 3 ) Etc. purchased from Weichan Shengchuan chemical Co., ltd; hydrated lime with calcium content of more than 99% and density of 2.6g/cm 3 It is purchased from the processing factory of Shafang mineral products in Lingshu county.
Example 1
The embodiment provides a preparation method of a roadbed filler, which specifically comprises the following steps:
s1, preparing a mixed modified material: mixing 7 parts by weight of fly ash and 2 parts by weight of hydrated lime, stirring and mixing for 15min at a speed of 500r/min to obtain a material, and performing ball milling to obtain a mixed modified material;
the ball milling conditions are that agate balls are used as milling balls, ethanol is used as a ball milling medium, and the mass ratio of the materials is as follows: agate ball: respectively weighing the materials, the agate balls and the ethanol according to the mass ratio of 1;
s2, preparing a polydopamine modified material: adding 20 parts by weight of the mixed modified material prepared in the step S1 into 100 parts by weight of water, performing ultrasonic dispersion for 20min at 1000W, adding 25 parts by weight of dopamine hydrochloride and 2 parts by weight of catalyst, heating to 40 ℃, stirring at 500r/min for reaction for 2h, centrifuging at 3000r/min for 20min, washing with clear water, and drying at 70 ℃ for 2h to obtain a polydopamine modified material;
the catalyst is a Tris-HCl solution containing 3wt% of cobalt chloride and having pH = 6.5;
s3, preparing modified loess: adding 10 parts by weight of loess into 50 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 5 parts by weight of the polydopamine modified material obtained in the step S2, mixing for 10min under stirring, heating to 35 ℃, reacting for 1h under stirring, filtering, and drying for 2h at 70 ℃ to obtain modified loess;
s4, acidizing: adding the modified loess prepared in the step S3 into 1mol/L hydrochloric acid solution, and soaking for 30min, wherein the solid-to-liquid ratio of the modified loess to the 1mol/L hydrochloric acid solution is 1; filtering, washing with clear water to obtain acidified modified loess;
s5, hydrophobization treatment: adding 10 parts by weight of the acidified modified loess obtained in the step S4 into 100 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 3 parts by weight of anionic surfactant, stirring and mixing for 15min, heating to 30 ℃, stirring at 500r/min for reaction for 0.5h to obtain hydrophobized modified loess;
the anionic surfactant is a compound mixture of sodium octadecyl sulfate and sodium octadecyl sulfonate, and the mass ratio is 3;
s6, mixing treatment: adding 100 parts by weight of the hydrophobic modified loess prepared in the step S5 into 200 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 3 parts by weight of sodium sulfate, stirring and mixing at 500r/min for 15min, evaporating to remove the solvent, and drying at 70 ℃ for 2h to obtain a mixture;
s7, dynamic compaction and compaction treatment: and (3) performing dynamic compaction and compaction treatment on the mixture prepared in the step (S6) under the pressure of 5MPa to prepare the roadbed filler, wherein the diagram 1 is an SEM diagram of the prepared roadbed filler, and the roadbed filler has low porosity.
Example 2
The embodiment provides a preparation method of a roadbed filler, which specifically comprises the following steps:
s1, preparing a mixed modified material: mixing 12 parts by weight of fly ash and 5 parts by weight of hydrated lime, stirring and mixing for 20min at a speed of 500r/min to obtain a material, and performing ball milling to obtain a mixed modified material;
the ball milling conditions are that agate balls are used as milling balls, ethanol is used as a ball milling medium, and the mass ratio of the materials: agate ball: respectively weighing the materials, the agate balls and the ethanol according to the mass ratio of 1;
s2, preparing a polydopamine modified material: adding 30 parts by weight of the mixed modified material prepared in the step S1 into 100 parts by weight of water, performing ultrasonic dispersion for 20min at 1000W, adding 32 parts by weight of dopamine hydrochloride and 3 parts by weight of catalyst, heating to 50 ℃, stirring and reacting at 500r/min for 4h, centrifuging at 3000r/min for 20min, washing with clear water, and drying at 70 ℃ for 2h to obtain a polydopamine modified material;
the catalyst is a Tris-HCl solution with 5wt% of cobalt sulfate and pH = 6.7;
s3, preparing modified loess: adding 15 parts by weight of loess into 50 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 7 parts by weight of polydopamine modified material obtained in the step S2, mixing under stirring for 15min, heating to 45 ℃, reacting under stirring for 3h, filtering, and drying at 70 ℃ for 2h to obtain modified loess;
s4, acidizing: adding the modified loess prepared in the step S3 into a 3mol/L sulfuric acid solution for soaking for 50min, wherein the solid-liquid ratio of the modified loess to the 3mol/L sulfuric acid solution is 1; filtering, washing with clear water to obtain acidified modified loess;
s5, hydrophobization treatment: adding 10 parts by weight of the acidified modified loess obtained in the step S4 into 100 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 5 parts by weight of anionic surfactant, stirring and mixing for 20min, heating to 40 ℃, and stirring and reacting at 500r/min for 1.5h to obtain hydrophobized modified loess;
the anionic surfactant is a compound mixture of sodium octadecyl sulfate and sodium octadecyl sulfonate, and the mass ratio is 5;
s6, mixing treatment: adding 100 parts by weight of the hydrophobized modified loess prepared in the step S5 into 200 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 5 parts by weight of magnesium sulfate, stirring and mixing at 500r/min for 20min, evaporating to remove the solvent, and drying at 70 ℃ for 2h to obtain a mixture;
s7, dynamic compaction and compaction treatment: and (5) performing dynamic compaction and compaction treatment on the mixture prepared in the step (S6) under the pressure of 7MPa to prepare the roadbed filling.
Example 3
The embodiment provides a preparation method of a roadbed filler, which specifically comprises the following steps:
s1, preparing a mixed modified material: mixing 10 parts by weight of fly ash and 3.5 parts by weight of hydrated lime, stirring and mixing at 500r/min for 17min to obtain a material, and performing ball milling to obtain a mixed modified material;
the ball milling conditions are that agate balls are used as milling balls, ethanol is used as a ball milling medium, and the mass ratio of the materials is as follows: agate ball: respectively weighing the materials, the agate balls and the ethanol according to the mass ratio of 1: 1.5;
s2, preparing a polydopamine modified material: adding 25 parts by weight of the mixed modified material prepared in the step S1 into 100 parts by weight of water, performing ultrasonic dispersion for 20min at 1000W, adding 27 parts by weight of dopamine hydrochloride and 2.5 parts by weight of catalyst, heating to 45 ℃, stirring at 500r/min for reaction for 3h, centrifuging at 3000r/min for 20min, washing with clear water, and drying at 70 ℃ for 2h to obtain a polydopamine modified material;
the catalyst is a Tris-HCl solution with 4wt% of cobalt chloride and pH = 6.6;
s3, preparing modified loess: adding 12 parts by weight of loess into 50 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 6 parts by weight of polydopamine modified material obtained in the step S2, mixing under stirring for 12min, heating to 40 ℃, reacting under stirring for 2h, filtering, and drying at 70 ℃ for 2h to obtain modified loess;
s4, acidizing: adding the modified loess prepared in the step S3 into a sulfuric acid solution of 2mol/L for soaking for 40min, wherein the solid-to-liquid ratio of the modified loess to the sulfuric acid solution of 2mol/L is 1; filtering, washing with clear water to obtain acidified modified loess;
s5, hydrophobization treatment: adding 10 parts by weight of the acidified modified loess obtained in the step S4 into 100 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 4 parts by weight of anionic surfactant, stirring and mixing for 17min, heating to 35 ℃, and stirring and reacting for 1h at 500r/min to obtain hydrophobized modified loess;
the anionic surfactant is a compound mixture of sodium octadecyl sulfate and sodium octadecyl sulfonate, and the mass ratio of the anionic surfactant to the sodium octadecyl sulfate is 4;
s6, mixing treatment: adding 100 parts by weight of the hydrophobized modified loess prepared in the step S5 into 200 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 4 parts by weight of potassium sulfate, stirring and mixing at 500r/min for 17min, evaporating to remove the solvent, and drying at 70 ℃ for 2h to obtain a mixture;
s7, dynamic compaction and compaction treatment: and (5) performing dynamic compaction and compaction treatment on the mixture prepared in the step (S6) under the pressure of 6MPa to prepare the roadbed filling.
Example 4
Compared with example 3, the anionic surfactant is single sodium octadecyl sulfate, and other conditions are not changed.
Example 5
Compared with example 3, the anionic surfactant is single sodium octadecyl sulfonate, and other conditions are not changed.
Comparative example 1
Compared with example 3, the ball milling treatment was not performed in step S1, and other conditions were not changed.
The method comprises the following specific steps:
s1, preparing a mixed modified material: 10 parts of fly ash and 3.5 parts of hydrated lime are mixed, and stirred and mixed for 17min at the speed of 500r/min to obtain the mixed modified material.
Comparative example 2
Compared with the example 3, the fly ash is not added in the step S1, and other conditions are not changed.
The method comprises the following specific steps:
s1, preparing a mixed modified material: ball-milling 13.5 parts by weight of slaked lime to obtain a mixed modified material;
the ball milling conditions are that agate balls are used as milling balls, ethanol is used as a ball milling medium, and the mass ratio of hydrated lime: agate ball: the mass ratio of the ethanol is 1.
Comparative example 3
Compared with example 3, no slaked lime was added in step S1, and other conditions were not changed.
The method comprises the following specific steps:
s1, preparing a mixed modified material: performing ball milling on 13.5 parts by weight of fly ash to obtain a mixed modified material;
the ball milling conditions are that agate balls are used as milling balls, ethanol is used as a ball milling medium, and the mass ratio of the coal ash: agate ball: the mass ratio of the ethanol is 1.
Comparative example 4
Step S2 was not performed, and other conditions were not changed as compared with example 3.
The method specifically comprises the following steps:
s1, preparing a mixed modified material: mixing 10 parts by weight of fly ash and 3.5 parts by weight of hydrated lime, stirring and mixing at 500r/min for 17min to obtain a material, and performing ball milling to obtain a mixed modified material;
the ball milling conditions are that agate balls are used as milling balls, ethanol is used as a ball milling medium, and the mass ratio of the materials is as follows: agate ball: respectively weighing the materials, the agate balls and the ethanol according to the mass ratio of 1: 1.5;
s2, preparing modified loess: adding 12 parts by weight of loess into 50 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 6 parts by weight of the mixed modified material obtained in the step S1, mixing for 12min under stirring, heating to 40 ℃, reacting for 2h under stirring, filtering, and drying at 70 ℃ for 2h to obtain modified loess;
s3, acidizing: adding the modified loess prepared in the step S2 into a sulfuric acid solution of 2mol/L for soaking for 40min, wherein the solid-to-liquid ratio of the modified loess to the sulfuric acid solution of 2mol/L is 1; filtering, washing with clear water to obtain acidified modified loess;
s4, hydrophobization treatment: adding 10 parts by weight of the acidified modified loess prepared in the step S3 into 100 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 4 parts by weight of anionic surfactant, stirring and mixing for 17min, heating to 35 ℃, and stirring and reacting for 1h at 500r/min to obtain hydrophobized modified loess;
the anionic surfactant is a compound mixture of sodium octadecyl sulfate and sodium octadecyl sulfonate, and the mass ratio is 4;
s5, mixing treatment: adding 100 parts by weight of the hydrophobized modified loess prepared in the step S4 into 200 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 4 parts by weight of potassium sulfate, stirring and mixing at 500r/min for 17min, evaporating to remove the solvent, and drying at 70 ℃ for 2h to obtain a mixture;
s6, dynamic compaction and compaction treatment: and (4) performing dynamic compaction and compaction treatment on the mixture prepared in the step (S5) under the pressure of 6MPa to prepare the roadbed filling.
Comparative example 5
Step S4 was not performed, and other conditions were not changed, as compared with example 3.
The method specifically comprises the following steps:
s1, preparing a mixed modified material: mixing 10 parts by weight of fly ash and 3.5 parts by weight of hydrated lime, stirring and mixing at 500r/min for 17min to obtain a material, and performing ball milling to obtain a mixed modified material;
the ball milling conditions are that agate balls are used as milling balls, ethanol is used as a ball milling medium, and the mass ratio of the materials: agate ball: respectively weighing the materials, the agate balls and the ethanol according to the mass ratio of 1: 1.5;
s2, preparing a polydopamine modified material: adding 25 parts by weight of the mixed modified material prepared in the step S1 into 100 parts by weight of water, performing ultrasonic dispersion for 20min at 1000W, adding 27 parts by weight of dopamine hydrochloride and 2.5 parts by weight of catalyst, heating to 45 ℃, stirring at 500r/min for reaction for 3h, centrifuging at 3000r/min for 20min, washing with clear water, and drying at 70 ℃ for 2h to obtain a polydopamine modified material;
the catalyst is a Tris-HCl solution with 4wt% of cobalt chloride and pH = 6.6;
s3, preparing modified loess: adding 12 parts by weight of loess into 50 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 6 parts by weight of the polydopamine modified material obtained in the step S2, mixing for 12min under stirring, heating to 40 ℃, reacting for 2h under stirring, filtering, and drying for 2h at 70 ℃ to obtain modified loess;
s4, hydrophobization treatment: adding 10 parts by weight of the modified loess prepared in the step S3 into 100 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 4 parts by weight of anionic surfactant, stirring and mixing for 17min, heating to 35 ℃, and stirring and reacting for 1h at 500r/min to obtain hydrophobized modified loess;
the anionic surfactant is a compound mixture of sodium octadecyl sulfate and sodium octadecyl sulfonate, and the mass ratio is 4;
s5, mixing treatment: adding 100 parts by weight of the hydrophobized modified loess prepared in the step S4 into 200 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 4 parts by weight of potassium sulfate, stirring and mixing at 500r/min for 17min, evaporating to remove the solvent, and drying at 70 ℃ for 2h to obtain a mixture;
s6, dynamic compaction and compaction treatment: and (5) performing dynamic compaction and compaction treatment on the mixture prepared in the step (S5) under the pressure of 6MPa to prepare the roadbed filling.
Comparative example 6
Steps S4 and S5 were not performed, and other conditions were not changed as compared with example 3.
The method specifically comprises the following steps:
s1, preparing a mixed modified material: mixing 10 parts by weight of fly ash and 3.5 parts by weight of hydrated lime, stirring and mixing at 500r/min for 17min to obtain a material, and performing ball milling to obtain a mixed modified material;
the ball milling conditions are that agate balls are used as milling balls, ethanol is used as a ball milling medium, and the mass ratio of the materials: agate ball: respectively weighing the materials, the agate balls and the ethanol according to the mass ratio of 1: 1.5;
s2, preparing a polydopamine modified material: adding 25 parts by weight of the mixed modified material prepared in the step S1 into 100 parts by weight of water, performing ultrasonic dispersion for 20min at 1000W, adding 27 parts by weight of dopamine hydrochloride and 2.5 parts by weight of catalyst, heating to 45 ℃, stirring at 500r/min for reaction for 3h, centrifuging at 3000r/min for 20min, washing with clear water, and drying at 70 ℃ for 2h to obtain a polydopamine modified material;
the catalyst is a Tris-HCl solution with 4wt% of cobalt chloride and pH = 6.6;
s3, preparing modified loess: adding 12 parts by weight of loess into 50 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 6 parts by weight of the polydopamine modified material obtained in the step S2, mixing for 12min under stirring, heating to 40 ℃, reacting for 2h under stirring, filtering, and drying for 2h at 70 ℃ to obtain modified loess;
s4, mixing treatment: adding 100 parts by weight of the modified loess obtained in the step S3 into 200 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 4 parts by weight of potassium sulfate, stirring and mixing at 500r/min for 17min, evaporating to remove the solvent, and drying at 70 ℃ for 2h to obtain a mixture;
s5, dynamic compaction and compaction treatment: and (5) performing dynamic compaction and compaction treatment on the mixture prepared in the step (S4) under the pressure of 6MPa to prepare the roadbed filling.
Comparative example 7
Step S6 was not performed, and other conditions were not changed, as compared with example 3.
The method specifically comprises the following steps:
s1, preparing a mixed modified material: mixing 10 parts by weight of fly ash and 3.5 parts by weight of hydrated lime, stirring and mixing at 500r/min for 17min to obtain a material, and performing ball milling to obtain a mixed modified material;
the ball milling conditions are that agate balls are used as milling balls, ethanol is used as a ball milling medium, and the mass ratio of the materials is as follows: agate ball: respectively weighing the materials, the agate balls and the ethanol according to the mass ratio of 1;
s2, preparing a polydopamine modified material: adding 25 parts by weight of the mixed modified material prepared in the step S1 into 100 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 27 parts by weight of dopamine hydrochloride and 2.5 parts by weight of catalyst, heating to 45 ℃, stirring at 500r/min for reaction for 3h, centrifuging at 3000r/min for 20min, washing with clear water, and drying at 70 ℃ for 2h to obtain a poly-dopamine modified material;
the catalyst is a Tris-HCl solution with 4wt% of cobalt chloride and pH = 6.6;
s3, preparing modified loess: adding 12 parts by weight of loess into 50 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 6 parts by weight of the polydopamine modified material obtained in the step S2, mixing for 12min under stirring, heating to 40 ℃, reacting for 2h under stirring, filtering, and drying for 2h at 70 ℃ to obtain modified loess;
s4, acidizing: adding the modified loess prepared in the step S3 into a sulfuric acid solution of 2mol/L for soaking for 40min, wherein the solid-to-liquid ratio of the modified loess to the sulfuric acid solution of 2mol/L is 1; filtering, washing with clear water to obtain acidified modified loess;
s5, hydrophobization treatment: adding 10 parts by weight of the acidified modified loess obtained in the step S4 into 100 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 4 parts by weight of anionic surfactant, stirring and mixing for 17min, heating to 35 ℃, and stirring and reacting for 1h at 500r/min to obtain hydrophobized modified loess;
the anionic surfactant is a compound mixture of sodium octadecyl sulfate and sodium octadecyl sulfonate, and the mass ratio of the anionic surfactant to the sodium octadecyl sulfate is 4;
s6, dynamic compaction and compaction treatment: and (5) performing dynamic compaction and compaction treatment on the hydrophobized modified loess prepared in the step (S5) under the pressure of 6MPa to prepare the roadbed filling.
Comparative example 8
Step S7 was not performed, and other conditions were not changed as compared with example 3.
The method specifically comprises the following steps:
s1, preparing a mixed modified material: mixing 10 parts by weight of fly ash and 3.5 parts by weight of hydrated lime, stirring and mixing at 500r/min for 17min to obtain a material, and performing ball milling to obtain a mixed modified material;
the ball milling conditions are that agate balls are used as milling balls, ethanol is used as a ball milling medium, and the mass ratio of the materials: agate ball: respectively weighing the materials, the agate balls and the ethanol according to the mass ratio of 1: 1.5;
s2, preparing a polydopamine modified material: adding 25 parts by weight of the mixed modified material prepared in the step S1 into 100 parts by weight of water, performing ultrasonic dispersion for 20min at 1000W, adding 27 parts by weight of dopamine hydrochloride and 2.5 parts by weight of catalyst, heating to 45 ℃, stirring at 500r/min for reaction for 3h, centrifuging at 3000r/min for 20min, washing with clear water, and drying at 70 ℃ for 2h to obtain a polydopamine modified material;
the catalyst is a Tris-HCl solution containing 4wt% cobalt chloride, pH = 6.6;
s3, preparing modified loess: adding 12 parts by weight of loess into 50 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 6 parts by weight of the polydopamine modified material obtained in the step S2, mixing for 12min under stirring, heating to 40 ℃, reacting for 2h under stirring, filtering, and drying for 2h at 70 ℃ to obtain modified loess;
s4, acidizing: adding the modified loess prepared in the step S3 into a 2mol/L sulfuric acid solution for soaking for 40min, wherein the solid-to-liquid ratio of the modified loess to the 2mol/L sulfuric acid solution is 1; filtering, washing with clear water to obtain acidified modified loess;
s5, hydrophobization treatment: adding 10 parts by weight of the acidified modified loess obtained in the step S4 into 100 parts by weight of water, performing ultrasonic dispersion at 1000W for 20min, adding 4 parts by weight of anionic surfactant, stirring and mixing for 17min, heating to 35 ℃, and stirring and reacting for 1h at 500r/min to obtain hydrophobized modified loess;
the anionic surfactant is a compound mixture of sodium octadecyl sulfate and sodium octadecyl sulfonate, and the mass ratio is 4;
s6, mixing treatment: and (3) adding 100 parts by weight of the hydrophobized modified loess prepared in the step (S5) into 200 parts by weight of water, performing ultrasonic dispersion for 20min at 1000W, adding 4 parts by weight of potassium sulfate, stirring and mixing for 17min at 500r/min, evaporating to remove the solvent, and drying for 2h at 70 ℃ to obtain the roadbed filler.
Test example 1
The roadbed fillers prepared in the embodiments 1-5 and the comparative examples 1-8 of the invention are subjected to performance tests, which comprise the impact strength, the unconfined compressive strength and the water stability, and the unconfined compressive strength and the water stability after the addition of the stabilizer as evaluation indexes, and the tests are carried out according to the test regulations of inorganic binder stabilizing materials for highway engineering (JTGE 51-2009) and the test regulations of geotechnical engineering (JTGE 40-2007), and specifically comprise the following steps:
1) Adding a corresponding amount of water into the mixture according to the optimal water content determined by a compaction test, uniformly stirring, pressing into a cylindrical sample with the diameter of 5cm and the height of 5cm according to a standard, maintaining for 7 days and 28 days according to the standard, and testing the unconfined compressive strength for 7 days and the unconfined compressive strength for 28 days respectively;
2) And (3) testing water stability: soaking a sample which is maintained for 28 days in water for 24 hours, taking out the sample, naturally drying the sample, then soaking the sample again, drying the sample again, testing the compressive strength of the sample, and calculating the strength loss rate according to the following formula:
strength loss (%) = (average value of compression strength of test piece after two dry and wet cycles-average value of compression strength of test piece before immersion)/average value of compression strength of test piece before immersion x 100%
The test results of all tests are the average value of the test values of more than 5 samples, and the coefficient of variation is calculated according to the standard requirement.
The results are shown in tables 2-4.
TABLE 2
TABLE 3
TABLE 4
As can be seen from the above table, the roadbed filler prepared by the embodiments 1-3 of the invention has high water stability, large compressive strength and low strength loss rate, completely meets the requirements on roadbed filler in the compressive strength standard of lime industrial waste residue stabilized soil in the Highway road surface base course construction technical Specification (JTJ 034-2000), and can be used as roadbed filler of roads.
Test example 2
The roadbed fillers prepared in the embodiments 1-5 and the comparative examples 1-8 of the invention are subjected to frost heaving experiments, and the specific method is as follows:
(1) Preparing samples under the condition of maximum water content in each group of test examples 1, sealing and moisturizing for 24 hours to ensure that the moisture in the soil is fully and uniformly, and calculating the compactness of the samples after fully compacting and preparing the samples;
(2) Placing a sample cylinder filled with a sample into a low-temperature chamber, then installing a displacement sensor at the top of the sample to test the frost heaving deformation of the sample, embedding a temperature sensor in the sample, automatically collecting the temperature of the sample through a data acquisition instrument, and adopting a one-way freezing mode for the test;
(3) The frost heaving test was carried out under the water-supplemented condition, the temperature of the top plate was set to-12 to-10 ℃ and the temperature of the bottom plate was about 0 ℃ during the test, and the frost heaving rate was measured after 72 hours of holding, and the results are shown in table 5.
TABLE 5
| Group of | Frozen swelling capacity (mm) | Frost heaving ratio (%) |
| Example 1 | 2.37 | 1.62 |
| Example 2 | 2.34 | 1.60 |
| Example 3 | 2.30 | 1.57 |
| Example 4 | 3.02 | 2.12 |
| Example 5 | 3.10 | 2.24 |
| Comparative example 1 | 3.24 | 2.45 |
| Comparative example 2 | 3.27 | 2.49 |
| Comparative example 3 | 3.31 | 2.51 |
| Comparative example 4 | 3.10 | 2.32 |
| Comparative example 5 | 3.57 | 2.75 |
| Comparative example 6 | 4.72 | 3.25 |
| Comparative example 7 | 2.53 | 1.73 |
| Comparative example 8 | 3.30 | 2.52 |
As can be seen from the above table, the roadbed fillers prepared in the embodiments 1 to 3 of the invention have the advantages of small frost heaving deformation, low frost heaving rate and good low temperature resistance.
Compared with the embodiment 3, the comparative example 1 has the advantages that the ball milling treatment is not carried out in the step S1, the freezing resistance is obviously reduced, and the mechanical property is reduced;
comparative examples 2 and 3 compared with example 3, the fly ash or the hydrated lime is not added in step S1, the mechanical properties are obviously reduced, and the high-valence metal ions in the fly ash and the hydrated lime can replace univalent cations in the loess, so that small particles form a stable flocculent structure, such as Ca in the fly ash and the hydrated lime 2+ Ion replacement of Na in soil + ，K + And the soil particles are attached to the surfaces of the particles to form aggregates, so that the stability of the soil body is effectively improved. The fly ash modified loess can achieve the aim of improving soil strength through hydration and flocculation in a short-term reaction and silicification in a long-term reaction, and the fly ash contains more active SiO 2 ，Al 2 O 3 ，Fe 2 O 3 The acidic oxides have low CaO content, so that the self-cohesion is poor, under a certain water environment, calcium hydroxide in hydrated lime compounded with the acidic oxides reacts with active oxides in the fly ash to crystallize, gradually permeates into the centers of silica gel and hydrated silicate from the surface of hydrated glass body, exists in a soil body framework form, and the formation of the crystals is irreversible, so that the soil body strength of the loess is obviously improved. In addition, the hydrated lime can be used for water absorption reaction, ion exchange-water gel connection, consolidation reaction, carbonation crystallization and the likePotassium ions and sodium ions absorbed on the surface of the soil mass clay are replaced by divalent calcium ions into clay which absorbs divalent cations, so that calcium silicate compounds, calcium aluminate compounds, gehlenite hydrates and the like are generated, particles in the soil mass form aggregates, and the strength of the soil mass is improved. The reaction time of lime and loess can reach 8-10 years, so that the strength of the modified loess is gradually increased in the period, and the later strength growth trend is more obvious.
Compared with the embodiment 3, the step S2 is not carried out, the freezing resistance and the mechanical property are both reduced, the mixed modified material comprises the nano fly ash and the nano hydrated lime, the nano fly ash and the nano hydrated lime are further reacted, a polydopamine layer is compounded on the surface of the mixed modified material, after the polydopamine modified material is mixed with the loess, the polydopamine layer is rich in hydroxyl, amino and carboxyl structures and has extremely strong viscosity, a hydrogen bond with strong acting force can be formed with the surface hydroxyl of the loess, the bonding effect among granules in the loess is improved by adding the viscous polydopamine modified material, the tiny viscous polydopamine modified material falls into the overhead pores among the loess granules, the soil body tends to be more compact, the strength of the loess is improved, and the permeability of the loess is reduced. Through adding polydopamine modified material in the loess, change the contact condition of the inside granule of loess, reduce the inside pore volume of loess soil body, improved the characteristics of porous gap, weak cementation that exist in the loess structure for the loess is changeed closely knit, and the porosity is lower, thereby has greatly strengthened the intensity of loess, has improved its mechanical properties.
Comparative example 5 compared with example 3, in which the freezing resistance was decreased without performing step S4, the present invention added modified loess to an acid solution to make the surface thereof have a large number of positive charge centers, thereby facilitating hydrophobic modification at a later stage. Reduce the capillary phenomenon of absorbing water inside the loess, have better low temperature resistance, the frost heaving deformation is less, and the frost heaving rate is low.
Compared with the embodiment 3, the anionic surfactant is single sodium dodecyl sulfate or dodecyl trimethyl ammonium chloride, the anti-freezing performance is reduced, the strength is reduced after dry and wet circulation, the hydrophobic alkyl chains of the sodium octadecyl sulfate and the sodium octadecyl sulfonate are longer, after hydrophobic modification, the long-chain alkyl chain is arranged at the outer end, the better hydrophobic effect is achieved, the capillary water absorption phenomenon inside the loess is greatly reduced, the drying inside the loess is favorably kept, and the synergistic effect is achieved by adding the anionic surfactant and the sodium octadecyl sulfate. Meanwhile, after the compound modification of the sodium octadecyl sulfate and the sodium octadecyl sulfonate, the prepared roadbed filling material has better low temperature resistance, smaller frost heaving deformation and lower frost heaving rate.
In comparative example 6, compared to example 3, in which the freezing resistance was significantly reduced without performing steps S4 and S5, and the strength was significantly reduced after dry-wet cycling, the modified loess was added to an acid solution to make the surface thereof have a large number of positive centers, so that after further addition of an anionic surfactant, the negative centers of the anionic surfactant and the positive centers of the modified loess surface are electrostatically attracted, and the long-chain alkyl chains of the anionic surfactant are oriented in opposite directions, thereby achieving hydrophobic modification. Because the inside capillary phenomenon that still exists of ordinary loess soil body, the shutoff is used in reducing the permeability, easily leads to inside moisture to be difficult to discharge rapidly, is unfavorable for maintaining the inside dry state of loess. Therefore, after the modified loess is subjected to hydrophobic modification, the surfaces of the internal capillaries are covered with hydrophobic alkyl chains, so that the phenomenon of capillary water absorption in the soil is greatly reduced, and the effect of keeping the soil dry is facilitated; has better low temperature resistance, smaller frost heaving deformation and low frost heaving rate.
Comparative example 7 compared with example 3, without step S6, the mechanical properties are reduced, and the invention adds a small amount of sulfate, which is used as an activator in the presence of fly ash to promote the hydration reaction of the active components in the fly ash, for example, hydrated calcium aluminate can further react with sulfate to form ettringite, thereby enhancing the mechanical properties of loess.
Compared with the example 3, the mechanical property and the low temperature resistance are reduced without the step S7, the density and the particle arrangement form of the prepared roadbed filling material are changed after the dynamic compaction and the compaction treatment, the internal porosity is lower, the capillary water absorption phenomenon is reduced, and the mechanical property and the frost resistance are obviously improved.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and should not be taken as limiting the scope of the present invention, which is intended to cover any modifications, equivalents, improvements, etc. within the spirit and scope of the present invention.
Claims (10)
1. A preparation method of a roadbed filler is characterized in that fly ash and hydrated lime are mixed and ball-milled to a nanometer level, then the mixture is modified by polydopamine, the modified loess is mixed with loess and reacts, the obtained modified loess is acidified and then further reacts with an anionic surfactant to carry out hydrophobization, then the obtained hydrophobization loess is mixed with a sulfate solution, and the roadbed filler is obtained after drying, dynamic compaction and compaction.
2. The method of claim 1, comprising the steps of:
s1, preparing a mixed modified material: uniformly mixing the fly ash and the hydrated lime to obtain a material, and performing ball milling to obtain a mixed modified material;
s2, preparing a polydopamine modified material: dispersing the mixed modified material prepared in the step S1 in water, adding dopamine hydrochloride and a catalyst, heating for reaction, centrifuging, washing and drying to obtain a polydopamine modified material;
s3, preparing modified loess: dispersing loess in water, adding the polydopamine modified material prepared in the step S2, uniformly mixing, heating for reaction, filtering, and drying to obtain modified loess;
s4, acidizing: adding the modified loess prepared in the step S3 into acid liquor for soaking, filtering and washing to obtain acidified modified loess;
s5, hydrophobization treatment: dispersing the acidified modified loess prepared in the step S4 in water, adding an anionic surfactant, uniformly mixing, and heating for reaction to obtain hydrophobized modified loess;
s6, mixing treatment: dispersing the hydrophobized modified loess prepared in the step S5 in water, adding sulfate, stirring and mixing uniformly, evaporating to remove the solvent, and drying to obtain a mixture;
s7, dynamic compaction and compaction treatment: and (5) performing dynamic compaction and compaction treatment on the mixture prepared in the step (S6) under a certain pressure to prepare the roadbed filling.
3. The preparation method according to claim 2, wherein the mass ratio of the fly ash to the hydrated lime in the step S1 is 7-12; the ball milling conditions are that agate balls are used as milling balls, ethanol is used as a ball milling medium, and the mass ratio of the materials: agate ball: respectively weighing the materials, the agate balls and the ethanol according to the mass ratio of 1; the mass ratio of the mixed modified material, the dopamine hydrochloride and the catalyst in the step S2 is 20-30; the catalyst is a Tris-HCl solution with 3-5wt% of cobalt salt and pH = 6.5-6.7; the heating reaction temperature is 40-50 ℃, and the time is 2-4h.
4. The preparation method according to claim 2, wherein the mass ratio of the loess and the polydopamine modified material in the step S3 is 10-15; the heating reaction is carried out at the temperature of 35-45 ℃ for 1-3h; the acid solution in the step S4 is 1-3mol/L hydrochloric acid or sulfuric acid solution; the soaking time is 30-50min; the solid-liquid ratio of the modified loess to the acid liquid is 1-5 g/mL.
5. The method according to claim 2, wherein the anionic surfactant in step S5 is at least one selected from the group consisting of sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium dodecylsulfonate, sodium hexadecylbenzenesulfonate, sodium hexadecylsulfonate, sodium hexadecylsulfate, sodium octadecyl benzenesulfonate, and sodium octadecyl sulfate; the mass ratio of the acidified modified loess to the anionic surfactant is 10-5; the heating reaction temperature is 30-40 ℃, and the time is 0.5-1.5h.
6. The preparation method of claim 5, wherein the anionic surfactant is a compound mixture of sodium stearyl sulfate and sodium stearyl sulfonate, and the mass ratio of the anionic surfactant to the sodium stearyl sulfate is 3-5.
7. The method according to claim 2, wherein the mass ratio of the hydrophobized modified loess and the sulfate in step S6 is 100; the sulfate is selected from at least one of sodium sulfate, potassium sulfate and magnesium sulfate; the pressure in step S7 is 5-7MPa.
8. The preparation method according to claim 2, comprising the steps of:
s1, preparing a mixed modified material: mixing 7-12 parts by weight of fly ash and 2-5 parts by weight of slaked lime, stirring and mixing for 15-20min to obtain a material, and performing ball milling to obtain a mixed modified material;
the ball milling conditions are that agate balls are used as milling balls, ethanol is used as a ball milling medium, and the mass ratio of the materials is as follows: agate ball: respectively weighing the materials, the agate balls and the ethanol according to the mass ratio of 1;
s2, preparing a polydopamine modified material: dispersing 20-30 parts by weight of the mixed modified material prepared in the step S1 in water, adding 25-32 parts by weight of dopamine hydrochloride and 2-3 parts by weight of catalyst, heating to 40-50 ℃ for reaction for 2-4h, centrifuging, washing and drying to obtain a polydopamine modified material;
the catalyst is a Tris-HCl solution with 3-5wt% of cobalt salt and pH = 6.5-6.7;
s3, preparing modified loess: dispersing 10-15 parts by weight of loess in water, adding 5-7 parts by weight of polydopamine modified material obtained in the step S2, mixing under stirring for 10-15min, heating to 35-45 ℃, reacting under stirring for 1-3h, filtering, and drying to obtain modified loess;
s4, acidizing: adding the modified loess prepared in the step S3 into 1-3mol/L hydrochloric acid or sulfuric acid solution for soaking for 30-50min, wherein the solid-to-liquid ratio of the modified loess to the 1-3mol/L hydrochloric acid or sulfuric acid solution is 1-3 g/mL; filtering, and washing to obtain acidified modified loess;
s5, hydrophobization treatment: dispersing 10 parts by weight of the acidified modified loess obtained in the step S4 in water, adding 3-5 parts by weight of an anionic surfactant, stirring and mixing for 15-20min, heating to 30-40 ℃, and stirring to react for 0.5-1.5h to obtain hydrophobized modified loess;
the anionic surfactant is a compound mixture of sodium octadecyl sulfate and sodium octadecyl sulfonate, and the mass ratio is 3-5;
s6, mixing treatment: dispersing 100 parts by weight of the hydrophobized modified loess prepared in the step S5 in water, adding 3-5 parts by weight of sulfate, stirring and mixing for 15-20min, evaporating to remove the solvent, and drying to obtain a mixture;
s7, dynamic compaction and compaction treatment: and (5) performing dynamic compaction and compaction treatment on the mixture prepared in the step (S6) under the pressure of 5-7MPa to prepare the roadbed filling.
9. A roadbed filler prepared by the preparation method of any one of claims 1-8.
10. Use of the roadbed filling according to claim 9 for the preparation of roadbeds for urban and rural highways.
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| US20130324674A1 (en) * | 2012-05-11 | 2013-12-05 | Navid Saleh | Polymeric Additive for Strength, Deformability, and Toughness Enhancement of Cemetitious Materials and Composites |
| CN104030309A (en) * | 2014-06-26 | 2014-09-10 | 淮阴工学院 | Fiber-type clay organic modification method based on dopamine modification |
| KR101640810B1 (en) * | 2016-03-29 | 2016-07-20 | 반윤명 | Paving Material Composition comprising Yellow Soil having improved strength and Paving Method using it |
| CN110862092A (en) * | 2019-12-05 | 2020-03-06 | 长沙理工大学 | Method for preparing polydopamine modified montmorillonite nano material by mechanical ball milling method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20130324674A1 (en) * | 2012-05-11 | 2013-12-05 | Navid Saleh | Polymeric Additive for Strength, Deformability, and Toughness Enhancement of Cemetitious Materials and Composites |
| CN104030309A (en) * | 2014-06-26 | 2014-09-10 | 淮阴工学院 | Fiber-type clay organic modification method based on dopamine modification |
| KR101640810B1 (en) * | 2016-03-29 | 2016-07-20 | 반윤명 | Paving Material Composition comprising Yellow Soil having improved strength and Paving Method using it |
| CN110862092A (en) * | 2019-12-05 | 2020-03-06 | 长沙理工大学 | Method for preparing polydopamine modified montmorillonite nano material by mechanical ball milling method |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117185762A (en) * | 2023-09-12 | 2023-12-08 | 宜都辉泽环保科技有限公司 | Waterproof curing agent and preparation method and application thereof |
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