CN116143468B - Premixed fluid state solidified salty soil and preparation method thereof - Google Patents
Premixed fluid state solidified salty soil and preparation method thereof Download PDFInfo
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- 239000002689 soil Substances 0.000 title claims abstract description 200
- 239000012530 fluid Substances 0.000 title claims abstract description 37
- 238000002360 preparation method Methods 0.000 title claims abstract description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 109
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 84
- 239000002893 slag Substances 0.000 claims abstract description 62
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 54
- 239000004568 cement Substances 0.000 claims abstract description 51
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 46
- 229910052742 iron Inorganic materials 0.000 claims abstract description 42
- 239000011780 sodium chloride Substances 0.000 claims abstract description 41
- 239000010881 fly ash Substances 0.000 claims abstract description 39
- 239000004576 sand Substances 0.000 claims abstract description 36
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 32
- 239000010959 steel Substances 0.000 claims abstract description 32
- 239000002699 waste material Substances 0.000 claims abstract description 25
- 159000000003 magnesium salts Chemical class 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 14
- 150000003839 salts Chemical class 0.000 claims abstract description 13
- 239000002994 raw material Substances 0.000 claims abstract description 9
- 239000003795 chemical substances by application Substances 0.000 claims description 54
- 238000003756 stirring Methods 0.000 claims description 33
- 238000012360 testing method Methods 0.000 claims description 32
- 238000002156 mixing Methods 0.000 claims description 30
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical group [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 28
- 239000002245 particle Substances 0.000 claims description 23
- 239000000203 mixture Substances 0.000 claims description 22
- 239000000047 product Substances 0.000 claims description 19
- 239000000126 substance Substances 0.000 claims description 17
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 13
- 239000004927 clay Substances 0.000 claims description 13
- 229910052593 corundum Inorganic materials 0.000 claims description 13
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 13
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 12
- 239000007787 solid Substances 0.000 claims description 11
- 238000007605 air drying Methods 0.000 claims description 9
- 238000005096 rolling process Methods 0.000 claims description 9
- 238000005070 sampling Methods 0.000 claims description 9
- 238000005303 weighing Methods 0.000 claims description 9
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims description 8
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 7
- 239000002253 acid Substances 0.000 claims description 7
- 229910052681 coesite Inorganic materials 0.000 claims description 7
- 229910052906 cristobalite Inorganic materials 0.000 claims description 7
- 239000000377 silicon dioxide Substances 0.000 claims description 7
- 229910052682 stishovite Inorganic materials 0.000 claims description 7
- 229910052905 tridymite Inorganic materials 0.000 claims description 7
- 239000000292 calcium oxide Substances 0.000 claims description 6
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 5
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 claims description 4
- 239000011398 Portland cement Substances 0.000 claims description 4
- 239000004480 active ingredient Substances 0.000 claims description 4
- 150000002500 ions Chemical class 0.000 claims description 4
- 239000008239 natural water Substances 0.000 claims description 4
- 239000005416 organic matter Substances 0.000 claims description 4
- 239000008399 tap water Substances 0.000 claims description 4
- 235000020679 tap water Nutrition 0.000 claims description 4
- 239000012535 impurity Substances 0.000 claims description 3
- 230000007935 neutral effect Effects 0.000 claims description 3
- 239000000463 material Substances 0.000 abstract description 41
- 239000002910 solid waste Substances 0.000 abstract description 15
- 239000003337 fertilizer Substances 0.000 abstract description 5
- 230000008961 swelling Effects 0.000 abstract description 5
- 238000004090 dissolution Methods 0.000 abstract description 4
- 238000004064 recycling Methods 0.000 abstract description 4
- 238000005265 energy consumption Methods 0.000 abstract description 2
- 230000002265 prevention Effects 0.000 abstract description 2
- 230000002787 reinforcement Effects 0.000 abstract description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 abstract 2
- 229910002092 carbon dioxide Inorganic materials 0.000 abstract 1
- 239000001569 carbon dioxide Substances 0.000 abstract 1
- 125000001309 chloro group Chemical class Cl* 0.000 abstract 1
- 238000006703 hydration reaction Methods 0.000 description 25
- 239000003513 alkali Substances 0.000 description 21
- 230000000052 comparative effect Effects 0.000 description 17
- 230000036571 hydration Effects 0.000 description 16
- 239000000460 chlorine Substances 0.000 description 12
- 238000010276 construction Methods 0.000 description 9
- 230000000694 effects Effects 0.000 description 9
- 239000012071 phase Substances 0.000 description 9
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 8
- 229910052801 chlorine Inorganic materials 0.000 description 8
- 239000011521 glass Substances 0.000 description 8
- 239000011148 porous material Substances 0.000 description 8
- 150000003841 chloride salts Chemical class 0.000 description 6
- 239000002131 composite material Substances 0.000 description 6
- 229910052500 inorganic mineral Inorganic materials 0.000 description 5
- 238000011068 loading method Methods 0.000 description 5
- 239000011707 mineral Substances 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 230000005284 excitation Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000011575 calcium Substances 0.000 description 3
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 150000001804 chlorine Chemical class 0.000 description 3
- 239000004567 concrete Substances 0.000 description 3
- 238000000635 electron micrograph Methods 0.000 description 3
- 238000012423 maintenance Methods 0.000 description 3
- 239000008188 pellet Substances 0.000 description 3
- 238000005086 pumping Methods 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 description 2
- 229920005372 Plexiglas® Polymers 0.000 description 2
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 2
- 239000002956 ash Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- IQYKECCCHDLEPX-UHFFFAOYSA-N chloro hypochlorite;magnesium Chemical compound [Mg].ClOCl IQYKECCCHDLEPX-UHFFFAOYSA-N 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- 229910017625 MgSiO Inorganic materials 0.000 description 1
- 235000003181 Panax pseudoginseng Nutrition 0.000 description 1
- 244000131316 Panax pseudoginseng Species 0.000 description 1
- 241000276425 Xiphophorus maculatus Species 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000013043 chemical agent Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 230000001808 coupling effect Effects 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 229910052634 enstatite Inorganic materials 0.000 description 1
- 238000005429 filling process Methods 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 230000000979 retarding effect Effects 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 229940099259 vaseline Drugs 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Classifications
-
- 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
- C04B28/04—Portland cements
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K17/00—Soil-conditioning materials or soil-stabilising materials
- C09K17/02—Soil-conditioning materials or soil-stabilising materials containing inorganic compounds only
- C09K17/10—Cements, e.g. Portland cement
-
- 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
- C04B2111/00732—Uses not provided for elsewhere in C04B2111/00 for soil stabilisation
- C04B2111/00741—Preventing erosion
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Soil Sciences (AREA)
- Soil Conditioners And Soil-Stabilizing Materials (AREA)
- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
Abstract
The invention belongs to the field of civil engineering materials, and particularly relates to premixed fluid-state cured saline soil and a preparation method thereof. The premixed fluid state solidified salty soil takes cohesive soil containing chlorine salt in coastal areas as a main material, and comprises the following raw materials in parts by mass: 80-100 parts of salty soil, 25-30 parts of iron tailing sand, 6-8 parts of cement, 8-10 parts of slag, 5-7 parts of steel slag, 3-4 parts of fly ash, 1.2-1.4 parts of magnesium salt, 0.7-0.9 part of excitant, 0.4-0.6 part of water reducer and 65-70 parts of water. The ready-mixed fluid state solidified saline soil prepared by the method can be widely applied to projects such as backfill of road foundations, fertilizer grooves and pipe culverts in coastal areas, reinforcement and seepage prevention of river courses and coastline embankments, solves the common project problems such as salt swelling, dissolution and subsidence, corrosiveness and the like in the saline soil, effectively reduces the use of cement high-energy consumption resources, reduces the consumption of energy sources and the emission of carbon dioxide, simultaneously utilizes a large amount of industrial solid wastes in a recycling manner, and changes waste into valuables.
Description
Technical Field
The invention belongs to the field of civil engineering materials, and particularly relates to premixed fluid-state cured saline soil and a preparation method thereof.
Background
In the construction process of foundation trenches and pipe galleries backfilling engineering in coastal areas, the problems of narrow backfilling space, large backfilling depth, unstable backfilling soil compaction quality and the like are often encountered. For the groove backfill and highway subgrade, the treatment of the backfill by using the two-eighth ash soil and the pseudo-ginseng ash soil is mostly adopted, or the soil body is directly replaced by using materials such as concrete, the working procedure is complex, the manufacturing cost is very high, a great amount of waste is caused, special areas such as mine goaf, foundation trench and fertilizer trench are directly backfilled by using industrial waste such as tailings or adopting the concrete, the construction surface is narrow, the construction is difficult, and the engineering cost is very high. Therefore, the ready-mixed fluid solidified soil with certain fluidity and strength can be widely applied to engineering. At present, the curing agent in the fluid curing soil is slurry prepared by cement, fly ash and a small amount of additive according to a proportion, and then is mixed with the soil to form a curing soil mixture.
The soil in coastal areas belongs to cohesive soil with plasticity index greater than 10 and containing chlorine salt, and the cohesive soil has the phenomena of uneven stirring, caking, low strength after hardening and the like due to the fact that the cohesive soil is high in viscosity in the traditional process for preparing fluid state solidified soil, and meanwhile, a large amount of soluble salt is contained in the cohesive soil, so that the solidified salty soil has engineering hazards of salt swelling, dissolution and corrosiveness and the like, can have serious corrosiveness on curing agent cement, influences normal hydration of the cement, and cannot be normally utilized in strength. The project construction in coastal areas all involves the problem of solidifying and utilizing the soil, so how to effectively utilize the excavated natural soil mass and solidify and improve the chlorine saline soil, and the preparation of fluid solidified soil with uniform texture and high strength is a great subject faced by the current geotechnical engineering field and even the whole construction industry.
The accumulated and piled up tailings in China have huge quantity and low comprehensive utilization, wherein the production amount of the iron tailings sand is about 4.76 hundred million tons, and the iron tailings sand accounts for 39.31 percent of the total production amount of the tailings. In order to improve the comprehensive utilization of the iron tailing sand, the utilization of the iron tailing sand to the preparation of the fluid solidified soil is one of effective ways for improving the recycling utilization of the iron tailing sand.
Disclosure of Invention
Aiming at the special soil property of the soil, the cementing material adopts a mode of composite mineral design and chemical excitation, cement and cementing material prepared by alkali excitation industrial solid waste are used for cooperatively curing and treating the chlorine-containing saline soil, the problems of salt swelling, sinkability, corrosiveness and the like of the chlorine-containing saline soil are solved, the cement strength is fully exerted, part of cement is replaced by the alkali excitation cementing material, and the use amount of cement is saved. Meanwhile, the invention successfully utilizes the bulk industrial solid waste iron tailing sand into the fluid solidified soil, has obvious effect of improving the strength of the solidified soil, can be widely applied to projects such as fertilizer tanks, pipe culverts and the like in coastal areas, solves the problems that the projects cannot be backfilled tightly due to the limitation of backfilling conditions, space and the like, and effectively utilizes the excavated natural soil. According to the preparation method of the ready-mixed fluid-state solidified salty soil, various industrial solid waste raw materials used for alkali-activated cementing materials are fully activated, and the problems of uneven stirring, caking and low strength after hardening caused by the fact that the viscosity of the soil is large in the traditional process preparation are solved, so that the prepared fluid-state solidified soil is uniform in texture.
In order to achieve the above purpose, the present invention adopts the following technical scheme.
The ready-mixed fluid-state solidified salty soil comprises the following raw materials in parts by mass: 80-100 parts of salty soil, 25-30 parts of iron tailing sand, 6-8 parts of cement, 8-10 parts of slag, 5-7 parts of steel slag, 3-4 parts of fly ash, 1.2-1.4 parts of magnesium salt, 0.7-0.9 part of excitant, 0.4-0.6 part of water reducer and 65-70 parts of water.
Further, the ion content c (Cl -1)/c(SO42-) in the salty soil is more than 2, and the salty soil belongs to chloride salty soil; the main component of the salt is NaCl, the content is 2% -3%, belonging to the medium salty soil; the clay is clay or powdery clay with a plasticity index Ip greater than 10; uncontaminated soil with organic matter content less than 5%.
Further, the fineness modulus of the iron tailing sand is 0.6-1.2, the continuous grading is carried out, and the natural water content is 2% -4%.
Further, the cement is ordinary Portland cement P.O42.5.
Further, the slag mainly comprises the following chemical components by mass percent, wherein the fineness of ：CaO35％-40％、SiO232％-35％、Al2O3 12％-15％、MgO 10％-11％、Fe2O3 2％-4％、Na2O 1％-2％, is above 200 meshes, and the specific surface area is 350-400m2/kg.
Further, the steel slag mainly comprises the following chemical components in percentage by mass: 36-39% of CaO, 2-3% of SiO 215％-17％、MgO 12％-13％、Al2O3 7％-8％、SO3, fineness of more than 300 meshes and specific surface area of 450-500m < 2 >/kg.
Further, the fly ash is first-grade fly ash, and mainly comprises the following chemical components in percentage by mass, wherein the fineness of ：SiO256％-60％、Al2O3 20％-25％、Fe2O3 5％-7％、CaO7％-10％、K2O 2％-3％, is above 300 meshes, and the specific surface area is 550-600m < 2 >/kg.
Further, the effective component of the magnesium salt is MgCl 2·6H2 O, and the content exceeds 98%.
Further, the exciting agent is sodium hydroxide solid particles with the content of active ingredients being more than 98 percent.
Further, the water reducer is a polycarboxylic acid high-performance water reducer, and the water reducing rate is 25% -30%.
Further, the water is tap water or clean neutral water without oil impurities, and the PH value is 6-8.
Further, the ready-mixed fluid state solidified salty soil is prepared by the following steps:
S1, crushing and air-drying waste soil excavated on site, removing foreign matters in the waste soil, and then rolling to prepare soil with smaller particle size;
S2, weighing the components for standby according to the composition of the raw materials;
s3, fully mixing and stirring the solid particles of the excitant sodium hydroxide and 20% of water to enable the solid particles to be fully dissolved in the water to prepare an excitant solution;
S4, fully mixing and stirring the polycarboxylic acid high-performance water reducer and the rest 80% of water to prepare a water reducer solution;
s5, mixing the excitant solution prepared in the step S3 with cement, slag, steel slag, fly ash and magnesium salt, and fully stirring for at least 300 seconds to prepare a curing agent solution;
And S6, slowly adding the salty soil and the iron tailing sand into the curing agent solution prepared in the step S5, adding the water reducing agent solution, stirring the mixture while adding the water reducing agent solution until the texture is uniform, sampling, testing the expansibility, and obtaining a finished product when the standard requirement value is reached.
Further, the standard requirement value is that the expansion degree of the mixture after three hours is more than or equal to 160mm.
Compared with the prior art, the invention has the following beneficial effects:
1. The curing agent adopted by the invention is compounded by cement and alkali-activated cementing materials, wherein the alkali-activated cementing materials are prepared by exciting industrial solid waste slag, steel slag and fly ash by NaOH, and meanwhile, the cementing products such as C-S-H, C-A-H and the like are generated, and meanwhile, (Ca, na) -A-S-H products (shown in figure 5) are also generated, high proportion of hydroxyl groups in the nanostructure of the products can be exchanged with chloride ions, the chloride salt components contained in the salty soil are physically adsorbed, meanwhile, various industrial solid waste used contains active aluminum oxide (Al 2Or 3-) and calcium oxide (CaO) which are combined with chloride ions under the action of alkali-activated agents to generate chlorine-containing hydrate friedel salt (Fs), and the reaction equation is shown as follows:
Al2Or3-+4CaO+2NaCl+11H2O＝3CaO·Al2O3·CaCl2·10H2O(Fs)+2NaOH
The chlorine salt component contained in the salty soil is chemically combined, the generated Fs can stably exist in solidified soil, clustered crystals are shown under a microstructure (shown in a figure 6), the pores of the solidified soil are filled, the solidified soil is more compact, the strength of the solidified soil is improved, naOH is generated by the reaction, free OH - in pore liquid is increased, the alkalinity of liquid phase is increased, the degree of solidification wastewater is improved, the gel hydrate generated by hydration is also increased, and the strength of the solidified soil is improved. After physical adsorption and chemical combination of the alkali-activated cementing material on the chloride salt component in the salty soil, the harm of the chloride salt to the delay and corrosion of cement hydration is effectively avoided, the cement in the composite cementing material is hydrated normally, the strength is fully utilized, the early strength is provided for the fluidized solidified soil, the alkalinity of a pore solution is increased by a byproduct Ca (OH) 2 generated by cement hydration, the alkali-activated cementing material is further activated, in addition, the CaO content in slag and steel slag is higher, and after the slag is dissolved in water, the solution is in the condition of Ca (OH) 2 saturation or supersaturation, so that an advantageous condition is created for cement hydration. The curing agent of the invention has the advantages that through the composite design of cement and alkali-activated cementing material, the curing strength is far higher than the strength of the singly-doped cement (comparative example 1) and the singly-doped alkali-activated cementing material (comparative example 2) with the same doping amount, in a system for curing the chlorine saline soil, the curing effect on the chlorine saline soil is excellent through the synergistic coupling effect between the cement and the alkali-activated cementing material, 70% -75% of cement is replaced by the alkali-activated cementing material, the consumption of high-consumption and high-pollution cement is saved, a resource utilization way is provided for industrial solid waste slag, steel slag and fly ash, and the invention is more reasonable in economy. Because the solution in the system is alkaline, part of active SiO 2 and Al 2O3 contained in the saline soil are also excited to participate in the hydration reaction of the curing agent, and a gelatinous hydration product is generated, so that the strength is improved.
2. The salinized soil in the coastal region contains soluble salt NaCl, so that the solidified salinized soil has engineering hazards such as salt swelling, dissolution and subsidence, corrosiveness and the like, and chloride ions can corrode reinforcing steel bars, so that the engineering safety is seriously affected. Aiming at the chlorine saline soil, the curing agent disclosed by the invention is designed by the composite minerals, and chloride ions in the pore solution are consumed after being subjected to physical adsorption and chemical combination, so that corrosion of reinforcing steel bars caused by the curing agent is avoided, and the safety of a fluid curing soil project is facilitated.
3. The hydration reaction among the industrial solid waste slag, the steel slag and the fly ash in the alkali-activated gelling system is mutually assisted and promoted, the mineral components of the steel slag are similar to cement clinker, and the hydrolysis of the mineral components releases OH - to have a certain activation effect on the slag and the fly ash, so that the hydration reaction consumes OH -, and in turn, the OH - is consumed, and the dissolution and hydration rate of the steel slag are improved.
4. The slag and the steel slag used in the invention contain a certain amount of MgO, which is a raw material component for preparing Magnesium Oxychloride Cement (MOC), and the magnesium salt is doped in the invention, so that the magnesium salt can react with the active oxide contained in the solid waste to generate MOC, partial cement is replaced, the MOC hydration reaction is also quicker, the early strength can be provided for the fluid-state solidified soil, the hydration reaction itself needs Cl - to participate, the influence of delaying hydration and corrosion by the chloride salt in the salty soil can be avoided, and the magnesium oxychloride cement can exist stably. Because the curing agent is mainly an alkali-activated cementing material system, the pH of the solution is higher, a favorable alkaline environment is created for the hydration reaction of MOC, and the products of the hydration reaction of MOC are mainly 5Mg (OH) 2·MgCl·8H2 O crystal phase (5 phase) and 3Mg (OH) 2·MgCl·8H2 O (3 phase), so that the strength of the product is higher, but the water resistance is poorer, and the water resistance of the product can be greatly improved by being doped with the water reducer. The water reducing agent can reduce the water consumption of the fluid-state solidified soil, further reduce free water gaps to improve the strength of the solidified soil, change the shape of MOC crystalline phase products, generate more gelatinous and platy water-resistant crystals (shown in figure 5), and effectively inhibit hydrolysis reaction of 5-phase crystals. Meanwhile, the water reducer also has a certain retarding effect, and avoids early initial setting of the fluid solidified soil, so that the expansion degree of the water reducer in site casting cannot meet the requirement of pumping construction.
5. Besides being a material in the alkali-activated cementing material system, the fly ash used in the invention has spherical shape (shown in figure 2) under microscopic conditions, has smooth surface, is favorable for improving the flow property of the fluid-state solidified soil due to a ball effect, and meanwhile, the SiO 2 component in the fly ash and the system generate indissolvable MgSiO 3,MgSiO3 which can fill micropores of 5 phases and 3 phases of MOC hydration products (shown in figure 6), so that the structure is more stable, the structure is more compact, water is difficult to enter, the water resistance of MOC is improved, and in addition, the fly ash can control the phase transformation, so that MOC hydration generates more five phases with high strength.
6. The fineness modulus of the iron tailing sand used by the invention is 0.6-1.2, and the iron tailing sand with smaller grain diameter is adopted to be more easily wrapped by a cementing material hydration product to form a cementing pellet, so that the pores among soil particles are effectively filled, and the prepared solidified soil is more compact and has higher strength. The gel pellets and the soil particles have larger contact area and are mutually adhered, thus improving the cohesive force c of the solidified soil, and simultaneously, when the gel pellets are mutually contacted, mechanical biting force (shown in figure 3) exists due to rough surface and uneven surface of the iron tailing sand, compression deformation is not easy to generate, and the internal friction angle of the solidified soil is improvedThereby being beneficial to the improvement of the macroscopic mechanical strength of the solidified soil. The mixing amount of the iron tailing sand can reach 25% -30%, the strength of solidified soil is improved by 20% -25% (table 2. Example 3 and comparative example 3), and finally, a large amount of industrial solid waste iron tailing sand is effectively utilized in a recycling way, so that waste is changed into valuable. In addition, the iron tailings can also act as a dispersing agent, so that the clay particles of the soil are not easy to agglomerate, the mixing of the fluid solidified soil is more uniform, and the flow property is improved (table 1, example 3 and comparative example 3).
7. Aiming at the problems that in the traditional process, the waste clay excavated in the coastal area is directly utilized to prepare the fluid state solidified soil, and the fluid state solidified soil is applied to the projects such as backfilling and the like, the stirring is uneven, caking exists, and the strength of the solidified soil is low. According to the preparation method of the ready-mixed fluid state solidified saline soil, firstly, after the on-site excavated soil is air-dried and crushed, the prepared fluid state solidified soil is uniform in texture, free of caking phenomenon and high in strength, is difficult to cause pipeline blockage during pumping construction, and directly adopts natural soil as a main material, so that resources are saved, and the environment is protected. In the preparation method of the fluid state solidified saline soil, provided by the invention, the excitant NaOH particles and 20% of water are mixed to form a high-concentration excitant solution, and then slag, steel slag and fly ash are added into the excitant solution and fully stirred for at least 300 seconds, so that the activity of the slag, the steel slag and the fly ash is fully excited, more gelled products are generated by hydration, and the prepared fluid state solidified soil has higher strength.
In a word, because of the special soil property of the salty cohesive soil in the coastal region, the invention provides a premixed fluid state solidified salty soil and a preparation method thereof, aiming at the special soil property, the curing agent is compounded by cement and alkali-activated cementing material, a series of reactions between the cement, the alkali-activated cementing material and soil components are mutually synergistic, the harm caused by chlorine salt is avoided, the problems of salt swelling, sinking and corrosive engineering of the salty soil are well solved, the doping of bulk industrial solid waste iron tailings has an obvious effect of improving the strength of the fluid state solidified soil, various solid wastes are utilized in a recycling way, the use of high-energy-consumption cement is reduced, and the salty soil is more economical and environment-friendly. The selection of the main material saline soil is also waste soil excavated on the engineering site, so that the occupation of land resources by the waste soil is reduced, the secondary treatment is avoided, and the environment is protected. The prepared ready-mixed fluid state solidified saline soil can be widely applied to projects such as backfilling of road foundations, fertilizer grooves and pipe culverts in coastal areas, reinforcement and seepage prevention of river courses and coastline embankments, solves the problems of uneven tamping of special-shaped end faces in narrow spaces, and meanwhile, the preparation method of the invention solves the problems of uneven stirring, caking and the like of the solidified soil in the conventional process.
Drawings
FIG. 1 is a construction flow chart of the ready-mixed fluid-state solidified saline soil of the invention;
FIG. 2 microscopic electron microscope photographs of fly ash under different conditions (a is the microscopic morphology of fly ash, b is the incorporation of fly ash into fluidized solidified soil);
FIG. 3 photographs of iron tailings under different conditions (a is iron tailings, b is iron tailings microscopic morphology, c is iron tailings incorporated into a fluidized solidified soil);
FIG. 4 comparative example 1 microscopic electron micrographs at different age of maintenance (7 days, 28 days, 90 days);
FIG. 5 comparative example 2 microscopic electron micrographs at different age of maintenance (7 days, 28 days, 90 days);
FIG. 6 example 3 microscopic electron micrographs at different age of maintenance (7 days, 28 days, 90 days).
Detailed Description
Some embodiments of the invention are disclosed below and one skilled in the art can, based on the disclosure herein, suitably modify the process parameters to achieve this. It is expressly noted that all such similar substitutions and modifications will be apparent to those skilled in the art, and are deemed to be included in the present invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those skilled in the relevant art that variations and modifications can be made in the methods and applications described herein, and in the practice and application of the techniques of this invention, without departing from the spirit or scope of the invention.
The ready-mixed fluid-state solidified salty soil comprises the following raw materials in parts by mass: 80-100 parts of salty soil, 25-30 parts of iron tailing sand, 6-8 parts of cement, 8-10 parts of slag, 5-7 parts of steel slag, 3-4 parts of fly ash, 1.2-1.4 parts of magnesium salt, 0.7-0.9 part of excitant, 0.4-0.6 part of water reducer and 65-70 parts of water.
Further, the ion content c (Cl -1)/c(SO42-) in the salty soil is more than 2, and the salty soil belongs to chloride salty soil; the main component of the salt is NaCl, the content is 2% -3%, belonging to the medium salty soil; the clay is clay or powdery clay with a plasticity index Ip greater than 10; uncontaminated soil with organic matter content less than 5%.
Further, the fineness modulus of the iron tailing sand is 0.6-1.2, the continuous grading is carried out, and the natural water content is 2% -4%.
Further, the cement is ordinary Portland cement P.O42.5.
Further, the slag mainly comprises the following chemical components by mass percent, wherein the fineness of ：CaO35％-40％、SiO232％-35％、Al2O3 12％-15％、MgO 10％-11％、Fe2O3 2％-4％、Na2O 1％-2％, is above 200 meshes, and the specific surface area is 350-400m2/kg.
Further, the steel slag mainly comprises the following chemical components in percentage by mass: 36-39% of CaO, 2-3% of SiO 215％-17％、MgO 12％-13％、Al2O3 7％-8％、SO3, fineness of more than 300 meshes and specific surface area of 450-500m < 2 >/kg.
Further, the fly ash is first-grade fly ash, and mainly comprises the following chemical components in percentage by mass, wherein the fineness of ：SiO256％-60％、Al2O3 20％-25％、Fe2O3 5％-7％、CaO7％-10％、K2O 2％-3％, is above 300 meshes, and the specific surface area is 550-600m < 2 >/kg.
Further, the effective component of the magnesium salt is MgCl 2·6H2 O, and the content exceeds 98%.
Further, the exciting agent is sodium hydroxide solid particles with the content of active ingredients being more than 98 percent.
Further, the water reducer is a polycarboxylic acid high-performance water reducer, and the water reducing rate is 25% -30%.
Further, the water is tap water or clean neutral water without oil impurities, and the PH value is 6-8.
Further, the ready-mixed fluid state solidified salty soil is prepared by the following steps:
S1, crushing and air-drying waste soil excavated on site, removing foreign matters in the waste soil, and then rolling to prepare soil with smaller particle size;
S2, weighing the components for standby according to the composition of the raw materials;
s3, fully mixing and stirring the solid particles of the excitant sodium hydroxide and 20% of water to enable the solid particles to be fully dissolved in the water to prepare an excitant solution;
S4, fully mixing and stirring the polycarboxylic acid high-performance water reducer and the rest 80% of water to prepare a water reducer solution;
s5, mixing the excitant solution prepared in the step S3 with cement, slag, steel slag, fly ash and magnesium salt, and fully stirring for at least 300 seconds to prepare a curing agent solution;
And S6, slowly adding the salty soil and the iron tailing sand into the curing agent solution prepared in the step S5, adding the water reducing agent solution, stirring the mixture while adding the water reducing agent solution until the texture is uniform, sampling, testing the expansibility, and obtaining a finished product when the standard requirement value is reached.
Further, the standard requirement value is that the expansion degree of the mixture after three hours is more than or equal to 160mm.
The following examples and comparative examples each employ the following parameters of the composition:
Wherein, the ion content c (Cl -1)/c(SO42-) =6.6 in the saline soil belongs to the chlorine saline soil; the main component of the salt is NaCl, the content is 2.8 percent, and the salt belongs to medium salty soil; the clay is clay with a plasticity index Ip of 17.3; uncontaminated soil with organic matter content of 2.3%.
The fineness modulus of the iron tailing sand is 0.8, the continuous grading is carried out, and the natural water content is 2.3%.
The cement is ordinary Portland cement P.O42.5.
The slag mainly comprises the following chemical components in percentage by mass, wherein the fineness of ：CaO37.1％、SiO234.7％、Al2O313.2％、MgO 10.6％、Fe2O32.4％、Na2O 1.3％, meshes is 500, and the specific surface area is 374m < 2 >/kg.
The steel slag mainly comprises the following chemical components in percentage by mass: caO36.1%, siO 2 15.6％、MgO 12.6％、Al2O37.4％、SO3 2.7.7%, fineness of 800 mesh, and specific surface area of 455m2/kg.
The fly ash is first-grade fly ash and mainly comprises the following chemical components in percentage by mass: siO 2 56.3％、Al2O324.1％、Fe2O3 5.8％、CaO7.4％、K2 O2.7%, fineness of 1000 meshes, and specific surface area of 556m2/kg.
The effective component of magnesium salt is MgCl 2·6H2 O with a content of 98.7%.
The exciting agent is sodium hydroxide solid particles with the active ingredient content of 99.3 percent.
The water reducer is a polycarboxylic acid high-performance water reducer, and the water reducing rate is 27.4%.
The water was tap water, pH 7.4.
Example 1.
The specific dosage of the materials is as follows:
salinized soil: 80 parts of iron tailing sand: 25 parts of cement: 6 parts of slag: 8 parts of steel slag: 5 parts of fly ash: 3 parts of magnesium salt: 1.2 parts of an exciting agent: 0.7 parts of water reducer: 0.4 parts of water: 65 parts.
The preparation process is as follows:
S1, pre-treating waste soil excavated on site, crushing, air-drying, removing foreign matters in the waste soil, and then rolling to prepare soil with smaller particle size;
S2, weighing the components for standby according to the specific dosage of each material;
S3, fully mixing and stirring 0.7 part of exciting agent and 13 parts of water to fully dissolve the exciting agent in the water to prepare an exciting agent solution;
s4, mixing 0.4 part of water reducer with 52 parts of water to prepare a water reducer solution;
S5, adding 6 parts of cement, 8 parts of slag, 5 parts of steel slag, 3 parts of fly ash and 1.2 parts of magnesium salt into the excitant solution prepared in the step S3, and fully stirring for at least 300 seconds to prepare a curing agent solution;
And S6, slowly adding 80 parts of pretreated saline soil and 25 parts of iron tailing sand into the curing agent solution prepared in the step S5, adding the water reducing agent solution prepared in the step S4, stirring the mixture while adding the water reducing agent solution until the texture is uniform, sampling, testing the expansion degree, and judging the mixture to be qualified when the three-hour expansion degree after mixing is more than or equal to 160mm according to the specification requirement.
Standard curing was carried out to a specified age after sample loading, unconfined compressive strength was tested, and test data were recorded as shown in tables 1 and 2.
Example 2.
The specific dosage of the materials is as follows:
salinized soil: 90 parts of iron tailing sand: 28 parts of cement: 7 parts of slag: 9 parts of steel slag: 6 parts of fly ash: 3.5 parts of magnesium salt: 1.3 parts of an exciting agent: 0.8 parts of water reducer: 0.5 parts of water: 68 parts.
The preparation process is as follows:
S1, pre-treating waste soil excavated on site, crushing, air-drying, removing foreign matters in the waste soil, and then rolling to prepare soil with smaller particle size;
S2, weighing the components for standby according to the specific dosage of each material;
s3, fully mixing and stirring 0.8 part of exciting agent and 13.6 parts of water to fully dissolve the exciting agent in the water to prepare an exciting agent solution;
s4, mixing 0.5 part of water reducer with 54.4 parts of water to prepare a water reducer solution;
s5, adding 7 parts of cement, 9 parts of slag, 6 parts of steel slag, 3.5 parts of fly ash and 1.3 parts of magnesium salt into the excitant solution prepared in the step S3, and fully stirring for at least 300 seconds to prepare a curing agent solution;
And S6, slowly adding 90 parts of pretreated saline soil and 28 parts of iron tailing sand into the curing agent solution prepared in the step S5, adding the water reducing agent solution prepared in the step S4, stirring the mixture while adding the water reducing agent solution until the texture is uniform, sampling, testing the expansion degree, and judging the mixture to be qualified when the three-hour expansion degree after mixing is more than or equal to 160mm according to the specification requirement.
Standard curing was carried out to a specified age after sample loading, unconfined compressive strength was tested, and test data were recorded as shown in tables 1 and 2.
Example 3.
The specific dosage of the materials is as follows:
Salinized soil: 100 parts of iron tailing sand: 30 parts of cement: 8 parts of slag: 10 parts of steel slag: 7 parts of fly ash: 4 parts of magnesium salt: 1.4 parts of an exciting agent: 0.9 parts of water reducer: 0.6 parts of water: 70 parts.
The preparation process is as follows:
S1, pre-treating waste soil excavated on site, crushing, air-drying, removing foreign matters in the waste soil, and then rolling to prepare soil with smaller particle size;
S2, weighing the components for standby according to the specific dosage of each material;
S3, fully mixing and stirring 0.9 part of exciting agent and 14 parts of water to fully dissolve the exciting agent in the water to prepare an exciting agent solution;
s4, mixing 0.6 part of water reducer with 56 parts of water to prepare a water reducer solution;
S5, adding 8 parts of cement, 10 parts of slag, 7 parts of steel slag, 4 parts of fly ash and 1.4 parts of magnesium salt into the excitant solution prepared in the S3, and fully stirring for at least 300 seconds to prepare a curing agent solution;
And S6, slowly adding 100 parts of pretreated saline soil and 30 parts of iron tailing sand into the curing agent solution prepared in the step S5, adding the water reducing agent solution prepared in the step S4, stirring the mixture while adding the water reducing agent solution until the texture is uniform, sampling, testing the expansion degree, and judging the mixture to be qualified when the three-hour expansion degree after mixing is more than or equal to 160mm according to the specification requirements.
Standard curing was carried out to a specified age after sample loading, unconfined compressive strength was tested, and test data were recorded as shown in tables 1 and 2.
Comparative example 1.
The specific dosage of the materials is as follows:
salinized soil: 100 parts of iron tailing sand: 30 parts of cement: 30.4 parts of water reducer: 0.6 parts of water: 70 parts of the preparation process comprises the following steps:
S1, pre-treating waste soil excavated on site, crushing, air-drying, removing foreign matters in the waste soil, and then rolling to prepare soil with smaller particle size;
S2, weighing the components for standby according to the specific dosage of each material;
S3, fully mixing and stirring 30.4 parts of cement, 70 parts of water and 0.6 part of water reducer to prepare solid
A solution of a chemical agent;
and S4, adding 100 parts of saline soil and 30 parts of iron tailing sand into the curing agent solution prepared in the step S3, stirring the mixture while adding the saline soil and the 30 parts of iron tailing sand until the texture is uniform, sampling and testing the expansion degree, and judging the mixture to be qualified when the expansion degree is more than or equal to 160mm three hours after mixing according to the specification requirements.
Standard curing was carried out to a specified age after sample loading, unconfined compressive strength was tested, and test data were recorded as shown in tables 1 and 2.
Comparative example 2.
The specific dosage of the materials is as follows:
Salinized soil: 100 parts of iron tailing sand: 30 parts of slag: 13 parts of steel slag: 9 parts of fly ash: 6 parts of magnesium salt: 2.4 parts of an exciting agent: 0.9 parts of water reducer: 0.6 parts of water: 70 parts.
The preparation process is as follows:
S1, pre-treating waste soil excavated on site, crushing, air-drying, removing foreign matters in the waste soil, and then rolling to prepare soil with smaller particle size;
S2, weighing the components for standby according to the specific dosage of each material;
S3, fully mixing and stirring 0.9 part of exciting agent and 14 parts of water to fully dissolve the exciting agent in the water to prepare an exciting agent solution;
s4, mixing 0.6 part of water reducer with 56 parts of water to prepare a water reducer solution;
s5, adding 13 parts of slag, 9 parts of steel slag, 6 parts of fly ash and 2.4 parts of magnesium salt into the excitant solution prepared in the step S3, and fully stirring for at least 300 seconds to prepare a curing agent solution;
And S6, slowly adding 100 parts of pretreated saline soil and 30 parts of iron tailing sand into the curing agent solution prepared in the step S5, adding the water reducing agent solution prepared in the step S4, stirring the mixture while adding the water reducing agent solution until the texture is uniform, sampling, testing the expansion degree, and judging the mixture to be qualified when the three-hour expansion degree after mixing is more than or equal to 160mm according to the specification requirements.
Comparative example 3.
Salinized soil: 100 parts of cement: 8 parts of slag: 10 parts of steel slag: 7 parts of fly ash: 4 parts of magnesium salt: 1.4 parts of an exciting agent: 0.9 parts of water reducer: 0.6 parts of water: 70 parts.
The preparation process is as follows:
S1, pre-treating waste soil excavated on site, crushing, air-drying, removing foreign matters in the waste soil, and then rolling to prepare soil with smaller particle size;
S2, weighing the components for standby according to the specific dosage of each material;
S3, fully mixing and stirring 0.9 part of exciting agent and 14 parts of water to fully dissolve the exciting agent in the water to prepare an exciting agent solution;
s4, mixing 0.6 part of water reducer with 56 parts of water to prepare a water reducer solution;
S5, adding 8 parts of cement, 10 parts of slag, 7 parts of steel slag, 4 parts of fly ash and 1.4 parts of magnesium salt into the excitant solution prepared in the S3, and fully stirring for at least 300 seconds to prepare a curing agent solution;
And S6, slowly adding 100 parts of pretreated saline soil into the curing agent solution prepared in the step S5, adding the water reducing agent solution prepared in the step S4, stirring while adding until the texture is uniform, sampling, testing the expansion degree, and judging the mixture to be qualified when the expansion degree is more than or equal to 160mm three hours after mixing according to the standard requirement.
Standard curing was carried out to a specified age after sample loading, unconfined compressive strength was tested, and test data were recorded as shown in tables 1 and 2.
The expansion degree and unconfined compressive strength of the prepared finished product fluid solidified soil are tested, and the concrete method comprises the following steps:
(1) Expansion degree test
The expansion degree testing device consists of a plexiglass plate and a plexiglass cylinder (only the side part of the cylinder) with a height of 80mm and a diameter of 80 mm. During the test, firstly, wiping dust on the inner wall of the organic glass cylinder and the surface of the organic glass flat plate by using a rag, coating a layer of vaseline on the inner wall of the organic glass, placing the organic glass cylinder on a horizontal organic glass flat plate, and wetting the surface of the organic glass flat plate; then filling the freshly mixed fluid state solidified soil into an organic glass cylinder, continuously vibrating in the sample filling process to ensure that the sample is tightly filled, scraping the surface of the freshly mixed fluid state solidified soil by a scraper after the freshly mixed fluid state solidified soil is filled, and wiping the outer cylinder wall and the fluid state soil scattered on the plate surface by a rag; after the sample is filled, the organic glass cylinder is slightly lifted vertically upwards, after 30 seconds, the maximum diameter and the minimum diameter of the mixture after spreading are measured by a steel ruler, and the average value of the maximum diameter and the minimum diameter is taken as the expansion degree. To ensure the reliability of the test, 3 parallel tests were performed on each group of samples, with the average value as the final spread.
(2) Unconfined compressive strength test
The inner diameter of a cylinder mould used for the test sample is 3.91cm and the height is 8cm, fresh fluid solidified soil is filled into the prepared mould, demoulding is carried out after 24 hours, the demoulded test sample is put into a standard curing box, and after curing to a specified age, an unconfined compressive strength test is carried out, and the unconfined compressive strength test is carried out according to the geotechnical test method standard (GB/T50123-1999). The instrument used in the test is YYW-2 strain control type unconfined pressure gauge produced by Nanjing soil instrument factory, and the compression rate is 0.8mm/min. To ensure the reliability of the test, 3 parallel tests were performed on each group of samples, with the average value being the final unconfined compressive strength.
Table 1 statistics of the spread test data of the ready-mixed fluid cured saline soil of the examples and comparative examples.
Table 2 statistics of unconfined compressive strength test data for ready-mixed fluid cured saline soil in examples and comparative examples.
As can be seen from the table, the strength and the expansion degree of the fluid-state solidified saline soil prepared by the preparation method of the embodiment 1-3 meet the requirements of the standard technical standards for pre-mixed fluid-state solidified soil filling engineering (T/BGEA 001-2019), the 7d strength is more than 0.4MPa, the 28d strength is more than 0.8MPa, the expansion degree after 3h mixing is more than 160mm, and the fluid-state solidified saline soil can be used for pumping construction and is widely applied to the engineering of backfilling road foundations, fertilizer grooves and pipe culverts in coastal areas, reinforcing and seepage preventing embankments of river courses and coastline and the like.
Compared with the test data of comparative example 1, the strength of the solidified soil is higher than that of the solidified soil singly doped with cement in different ages under the condition of the same doping amount of the solidifying agent, the strength is improved by 28.4-40.1%, the consumption of 70-75% of high-consumption and high-pollution cement is replaced, a resource utilization way is provided for solid waste slag, steel slag and fly ash, and the method is more reasonable in economy.
As can be seen by comparing the test data of comparative example 2, the strength of the solidified soil of the invention is higher than that of the solidified soil of the singly-doped alkali-activated cementing material in different ages under the condition of the same doping amount of the curing agent, which indicates that the curing agent of the invention adopts a method of cement and alkali-activated cementing material composite design to generate ideal curing effect.
As is clear from comparison with the test data of comparative example 3, when industrial solid waste iron tailing sand is doped into the solidified soil, the strength of the solidified soil is improved by about 25 percent compared with the strength of solidified soil without the iron tailing sand, the doping amount can reach 25 to 30 percent, and the solid waste iron tailing sand in a large amount is effectively recycled, so that waste is changed into valuable.
As can be seen from comparison of fig. 4, 5 and 6, in the single cement-doped curing group in comparative example 1 in fig. 4, due to the effect of chloride salt in the salty soil on delaying cement hydration and corrosion, hydration products are fewer, pores are more, and the curing soil is not compact enough and has lower strength. FIG. 5 shows that the curing group of the single alkali-doped excited cementing material of the comparative example 2 has relatively slow hydration reaction, relatively few hydration products in the early 7d and 28d curing ages, relatively many micropores and relatively low strength of the cured soil, but when the curing age is increased to 90d, the hydration reaction is basically finished, and the strength of the cured soil is relatively slowly improved. In example 3 of fig. 6, the curing agent of the present invention adopts the means of "composite mineral design+chemical excitation", so that the effect is obvious, the early 7d curing soil has fewer pores and more hydration products, which is attributed to the physical and chemical adsorption of alkali-activated cementing material to chloride salt, so that the cement can be normally hydrated to provide early strength for the curing soil, and as the age is prolonged, the alkali-activated cementing material is continuously hydrated, and some products fill the curing soil pores, so that the curing soil is more compact and the strength is further improved.
Claims (10)
1. The ready-mixed fluid state solidified salty soil is characterized by comprising the following raw materials in parts by mass: 80-100 parts of saline soil, 25-30 parts of iron tailing sand, 6-8 parts of cement, 8-10 parts of slag, 5-7 parts of steel slag, 3-4 parts of fly ash, 1.2-1.4 parts of magnesium salt, 0.7-0.9 part of excitant, 0.4-0.6 part of water reducer and 65-70 parts of water; the excitant is sodium hydroxide solid particles with the content of active ingredients being more than 98 percent.
2. The ready-mixed fluid-state cured saline soil of claim 1, wherein the saline soil has an ion content c (Cl -1）/c（SO4 2-) >2, belonging to the chloride saline soil; the main component of the salt is NaCl, the content is 2% -3%, belonging to the medium salty soil; the clay is clay or powdery clay with a plasticity index I p greater than 10; uncontaminated soil with organic matter content less than 5%.
3. The ready-mixed fluid cured saline soil of claim 1, wherein the iron tailing sand has a fineness modulus of 0.6-1.2, a continuous grading, and a natural water content of 2% -4%; the cement is ordinary Portland cement P ∙ O42.5.
4. The ready-mixed fluid-state solidified salty soil according to claim 1, wherein the slag mainly comprises the following chemical components by mass percent, wherein the fineness of ：CaO 35%-40%、SiO2 32%-35%、Al2O3 12%-15%、MgO 10%-11%、Fe2O3 2%-4%、Na2O 1%-2%, is above 200 meshes, and the specific surface area is 350-400m 2/kg.
5. The ready-mixed fluid-state solidified salty soil according to claim 1, wherein the steel slag mainly comprises the following chemical components in percentage by mass: 36-39% of CaO, 2-3% of SiO 2 15%-17%、MgO 12%-13%、Al2O3 7%-8%、SO3 , fineness of more than 300 meshes and specific surface area of 450-500 m 2/kg.
6. The ready-mixed fluid state solidified salty soil according to claim 1, wherein the fly ash is first-grade fly ash, and mainly comprises the following chemical components by mass percent ：SiO2 56%-60%、Al2O3 20%-25%、Fe2O3 5%-7%、CaO 7%-10%、K2O 2%-3%, with fineness of more than 300 meshes and specific surface area of 550-600m 2/kg.
7. The ready-mixed fluid-state solidified salty soil according to claim 1, wherein the magnesium salt comprises MgCl 2∙6H2 O with a content of more than 98%.
8. The ready-mixed fluid state cured saline soil according to claim 1, wherein the water reducing agent is a polycarboxylic acid high-performance water reducing agent, and the water reducing rate is 25% -30%; the water is tap water or clean neutral water without oil impurities, and the PH value is 6-8.
9. The preparation method of the ready-mixed fluid-state solidified salty soil is characterized by comprising the following steps of:
s1, crushing and air-drying waste soil excavated on site, removing foreign matters in the waste soil, and then rolling to prepare soil with smaller particle size;
S2, weighing the components for standby according to the composition of the raw materials in claim 1;
S3, fully mixing and stirring the solid particles of the excitant sodium hydroxide and 20% of water to enable the solid particles to be fully dissolved in the water to prepare an excitant solution;
s4, fully mixing and stirring the polycarboxylic acid high-performance water reducer and the rest 80% of water to prepare a water reducer solution;
s5, mixing the excitant solution prepared in the step S3 with cement, slag, steel slag, fly ash and magnesium salt, and fully stirring for at least 300 seconds to prepare a curing agent solution;
And S6, slowly adding the salty soil and the iron tailing sand into the curing agent solution prepared in the step S5, adding the water reducing agent solution, stirring the mixture while adding the water reducing agent solution until the texture is uniform, sampling, testing the expansibility, and obtaining a finished product when the standard requirement value is reached.
10. The method for preparing ready-mixed fluid cured saline soil according to claim 9, wherein the standard requirement value is that the expansion degree is more than or equal to 160mm three hours after mixing.
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