CN-121990800-A - Fly ash-based soft soil curing agent and preparation method and application thereof

CN121990800ACN 121990800 ACN121990800 ACN 121990800ACN-121990800-A

Abstract

The invention discloses a fly ash-based soft soil curing agent, a preparation method and application thereof, which belong to the technical field of soft soil curing agents, wherein after gradient activated fly ash, slag micropowder and metakaolin are mixed and stirred uniformly, quick hardening silicate cement and sulphoaluminate cement are added, stirring uniformly, adding the potassium hydroxide-anhydrous sodium sulfate mixture, the modified sodium silicate and the tartaric acid, stirring uniformly, adding the composite functional powder prepared by premixing nano silicon dioxide and methyl hydroxyethyl cellulose and other masses, and stirring uniformly; the gradient activated fly ash is calcined by the original fly ash sequentially through gradient temperature control to remove impurities and avoid active ingredient sintering, ultrasonic assisted water washing strengthens soluble salt removal, reduces salt interference, and low-temperature plasma activation obviously improves specific surface area of fly ash and exposure of active ingredients through high-energy particle bombardment, thereby fundamentally solving the strength problem caused by insufficient activity.

Inventors

CHEN XING
BIAN ZIJUN
ZHANG FAJIE
WU GUOXUN
LIN GUANGYUAN
CHEN ZHONGYONG
LUO GUAN
You Lianhuan
WANG LIPENG
LU CHENGZHENG
JIN LIPENG
LIN HAIMING
BAO QIANG
LI LETIAN
ZHANG GENG
ZHENG YUN
WANG FENG
Zeng Chuidong
LI ANG
ZHANG YONGLIANG
WANG RUNSHENG
JIAO ZIGUO

Assignees

华能罗源发电有限责任公司
苏州西热节能环保技术有限公司
西安热工研究院有限公司

Dates

Publication Date: 20260508
Application Date: 20260122

Claims (10)

1. The preparation method of the fly ash-based soft soil curing agent is characterized by comprising the following steps: Mixing and stirring the gradient activated fly ash, slag micropowder and metakaolin uniformly, adding quick-hardening silicate cement and sulphoaluminate cement, stirring uniformly for the second time, adding a potassium hydroxide-anhydrous sodium sulfate mixture, modified sodium silicate and tartaric acid, stirring uniformly for the third time, adding composite functional powder, stirring uniformly for the fourth time, detecting the mixing uniformity until the grain diameter variation coefficient is less than or equal to 5%, obtaining a mixed material, ball-milling the mixed material at low temperature, and aging at constant temperature and constant humidity to obtain the fly ash-based soft soil curing agent; The potassium hydroxide-anhydrous sodium sulfate mixture is prepared by mixing potassium hydroxide and anhydrous sodium sulfate and vacuum drying; The composite functional powder is prepared by premixing nano silicon dioxide and methyl hydroxyethyl cellulose and the like in mass; The gradient activated fly ash is prepared from raw fly ash by gradient temperature control calcination, ultrasonic assisted water washing and low-temperature plasma activation in sequence.
2. The method for preparing the fly ash-based soft soil curing agent according to claim 1, wherein the condition of gradient temperature control calcination comprises the steps of heating a first temperature zone to 400-450 ℃ at 3 ℃ per min, preserving heat for 1-1.5h, heating a second temperature zone to 750-800 ℃ at 5 ℃ per min, preserving heat for 2-2.5h, cooling a third temperature zone to 600-650 ℃, preserving heat for 1h, introducing 3-5% of ozone by volume, and cooling to room temperature after calcination to obtain gradient calcined fly ash; The ultrasonic assisted water washing condition comprises that adding gradient calcined fly ash into deionized water, carrying out ultrasonic treatment for 40-60min at the temperature of 35-45 ℃ with the ultrasonic power of 300-500W, stirring for 1 time every 20min, standing for 30min, detecting the conductivity of supernatant fluid, filtering when the conductivity is less than or equal to 40 mu S/cm, collecting filter cakes and drying, wherein the mass ratio of the gradient calcined fly ash to the deionized water is 1 (3-5), and the drying condition comprises that drying at the temperature of 105-110 ℃ until the water content is less than or equal to 3%; The low-temperature plasma activation condition comprises that argon and oxygen mixed gas is introduced, the treatment power is 150-200W, the pressure is 50-80Pa, the treatment time is 15-25min, and the volume ratio of the argon to the oxygen is 8:2.
3. The method for preparing the fly ash-based soft soil curing agent according to claim 1, wherein the vacuum drying condition comprises the following steps of 60-80 ℃ temperature, -0.08MPa vacuum degree and 1-2h time; The particle size of the rapid hardening silicate cement is less than or equal to 2mm, the particle size of the sulphoaluminate cement is less than or equal to 2mm, the particle size of the metakaolin is less than or equal to 2mm, and the particle size of the slag micro powder is less than or equal to 2mm; The conditions of mixing and stirring comprise 180-220r/min stirring for 8-12min; the condition of the second stirring uniformity comprises stirring for 12-16min at 220-260 r/min; the condition of stirring uniformly for the third time comprises stirring for 15-20min at 260-300 r/min; The fourth stirring condition comprises stirring for 8-10min at 300-320 r/min.
4. The preparation method of the fly ash-based soft soil curing agent according to claim 1, wherein the low-temperature ball milling condition comprises the steps of adding polyethylene glycol 400 accounting for 0.3-0.5% of the mass of the mixture as a grinding aid into zirconia balls, wherein the grinding temperature is 20-30 ℃, the grinding rotating speed is 250-300r/min, the grinding time is 1.5-2.5h, the particle size D50=5-8 μm after grinding, and the specific surface area is 600-700m 2 /kg; The constant temperature and humidity aging conditions comprise 15-20 ℃, 35-45% of relative humidity, 36-60h of aging time, 1 turn over every 10h, controlling the temperature rise in the aging process to be less than or equal to 5 ℃, detecting the initial setting time to be more than or equal to 50min after aging, and the final setting time to be less than or equal to 7h.
5. The method for preparing the fly ash-based soft soil curing agent according to claim 1, wherein the rapid hardening silicate cement is of grade P. O42.5R, and the initial setting time is less than or equal to 45min; The sulphoaluminate cement is 52.5-grade quick hardening sulphoaluminate cement, and the 1d compressive strength is more than or equal to 20MPa; The metakaolin is calcined kaolin at 700-800 ℃, the content of active alumina is more than or equal to 35%, and the specific surface area is more than or equal to 500m 2 /kg; The modified water glass is potassium-sodium composite water glass, and the solid content is more than or equal to 45%; The nano silicon dioxide is hydrophilic gas phase silicon dioxide, and the purity is more than or equal to 99.8%; the tartaric acid is of industrial grade, and the purity is more than or equal to 99%; the viscosity of the methyl hydroxyethyl cellulose is 200000 mPa.s; The specific surface area of the gradient activated fly ash is 550-650m 2 /kg; the 1d compressive strength of the fly ash-based soft soil curing agent is more than or equal to 5.0MPa,7d compressive strength not less than 5.5MPa,28d the compressive strength is more than or equal to 8.5MPa; When the original fly ash is the class I fly ash of the coal-fired power plant, the ignition loss is less than or equal to 5%, the silicon dioxide content is more than or equal to 55%, the aluminum oxide content is more than or equal to 25%, when the original fly ash is the class II fly ash, the heat preservation time of a first temperature zone is 2-2.5h, the treatment time of low-temperature plasma activation is 30-35min, and the specific surface area of gradient activated fly ash is more than or equal to 500m 2 /kg; When the fly ash-based soft soil curing agent is in a slurry shape, 1 part of water is added and stirred according to the water-to-material ratio (0.35-0.45), and an antifoaming agent accounting for 0.1-0.3% of the mass of the fly ash-based soft soil curing agent is added to prepare the slurry-shaped fly ash-based soft soil curing agent, wherein the antifoaming agent is an organosilicon antifoaming agent, the rotating speed of water adding and stirring is 2000-2500r/min, the stirring time is 8-10min, and the layering degree is less than or equal to 1% after standing for 30 min.
6. The fly ash-based soft soil curing agent is characterized by being prepared by adopting the preparation method of the fly ash-based soft soil curing agent according to any one of claims 1-5, and comprises 50% -70% of gradient activated fly ash, 10% -20% of rapid hardening silicate cement, 8% -15% of sulphoaluminate cement, 5% -12% of metakaolin, 8% -15% of slag micropowder, 3% -8% of anhydrous sodium sulfate, 1% -4% of potassium hydroxide, 2% -5% of modified water glass, 1% -3% of nano silicon dioxide, 1% -3% of tartaric acid and 1% -3% of methyl hydroxyethyl cellulose.
7. The application of the fly ash-based soft soil curing agent prepared by the preparation method of the fly ash-based soft soil curing agent according to any one of claims 1-5 in high-moisture-content soft soil, which is characterized in that the fly ash-based soft soil curing agent with the moisture content of 45% -55% is pre-pressed for 24 hours under the vacuum degree of-0.09 MPa by adopting a vacuum pre-pressing and electroosmosis combined technology, the moisture content is reduced to 30% -38% by adopting a voltage gradient of 1.8-2.2V/cm for electroosmosis dehydration for 3-5 hours, and the fly ash-based soft soil curing agent with the moisture content of 13% -16% is added, layered rolling is carried out after stirring until the compactness is more than or equal to 94%, and a moisturizing film is covered during curing.
8. The application of the fly ash-based soft soil curing agent prepared by the preparation method of the fly ash-based soft soil curing agent according to any one of claims 1-5 in high organic matter soft soil, which is characterized in that aiming at the high organic matter soft soil with the organic matter content of 8% -12%, ammonium persulfate-ferrous sulfate composite oxidant with the high organic matter soft soil mass of 2.5% -4% is added, stirring is carried out for 1-1.5h at a stirring speed of 120-160r/min, standing is carried out for 1.5h, slurry-shaped fly ash-based soft soil curing agent with the high organic matter soft soil mass of 16% -19% is added, and a curing pile with the diameter of 600-700mm is formed through high-pressure spin spraying, wherein the mass ratio of ammonium persulfate to ferrous sulfate in the slurry-shaped fly ash-based soft soil curing agent is 3:1, and the mass ratio of water to the fly ash-based soft soil curing agent is 0.4:1.
9. The application of the fly ash-based soft soil curing agent prepared by the preparation method of the fly ash-based soft soil curing agent according to any one of claims 1-5 in high-salt soft soil, which is characterized in that for the high-salt soft soil with the salt content of 1.5% -3%, zeolite powder-bentonite composite salt adsorbent with the mass of 3% -5% of the high-salt soft soil is added, the mixture is stirred uniformly and then stands for 2-3 hours, the fly ash-based soft soil curing agent with the mass of 14% -17% of the high-salt soft soil is added, the mixture is laminated and packed until the compaction degree is more than or equal to 95%, and when the salt content of the high-salt soft soil is more than 2%, barium carbonate with the mass of 2% -4% of the fly ash-based soft soil curing agent is added, and the mass ratio of zeolite powder to bentonite is 2:1.
10. The application of the fly ash-based soft soil curing agent prepared by the preparation method of the fly ash-based soft soil curing agent according to any one of claims 1-5 in conventional soft soil, wherein the fly ash-based soft soil curing agent with the water content of 20% -35%, the organic matter content of less than or equal to 8% and the salt content of less than or equal to 1.5% is added into the conventional soft soil, and the mixture is stirred for 15-20min and rolled until the compactness is more than or equal to 96%.

Description

Fly ash-based soft soil curing agent and preparation method and application thereof Technical Field The invention belongs to the technical field of soft soil curing agents, and particularly relates to a fly ash-based soft soil curing agent, a preparation method and application thereof. Background The soft soil curing agent is a functional material capable of improving the soft soil engineering characteristics through physical, chemical or physicochemical effects, and has the core effects of aiming at the problems of high soft soil moisture content, weak particle bonding force and low strength, reducing the soft soil porosity and improving the inter-particle bonding strength through ion exchange, gelation reaction or package agglomeration with soft soil particles, and finally realizing the aims of reducing the soft soil compressibility, improving the bearing capacity and improving the impermeability. While the traditional soft soil solidification depends on cement, lime and other natural resource consumption materials, the traditional soft soil solidification can meet the basic strength requirement, but long-term application faces the challenges of rising of raw material cost, higher carbon emission and the like, under the background, the industrial waste residue recycling becomes an important direction of the research and development of soft soil solidifying agent, the fly ash is one of the industrial waste residues with the largest discharge amount of a coal-fired power plant, the annual production amount is huge, if the long-term storage occupies land resources and can cause environmental influence due to dust emission and leaching, but the material contains active components such as silicon, aluminum and the like, can generate gelation reaction with moisture and clay minerals in soft soil under specific conditions, and has the potential of being converted into the raw materials of the soft soil solidifying agent. The Chinese patent application with publication number of CN119263709A provides a preparation method of fly ash-based soft soil curing agent and application thereof, aiming at utilizing fly ash, lime, gypsum, silica fume and the like as main raw materials, adding reinforcing agents such as metakaolin, nano silicon dioxide and exciting agents such as sodium hydroxide and sodium carbonate to improve the activity and strength of the curing agent. The method can improve the compressive strength and the water resistance of the curing agent by compounding reinforcing agents such as metakaolin, nano silicon dioxide and the like with exciting agents such as sodium hydroxide, but does not have a high-efficiency gradient activation pretreatment process for the fly ash, can not fully release the activity of the fly ash to solve the problem of insufficient early strength, and meanwhile lacks a special adaptation scheme for high-salt soft soil, does not provide differentiated soil pretreatment and construction processes for different types of soft soil (such as high organic matters and high-salt soft soil), is difficult to cover complex soft soil working conditions with different water contents, and does not guarantee the performance stability of the curing agent through processes such as low-temperature aging and the like. Therefore, a fly ash-based soft soil curing agent, a preparation method and application thereof are needed to be found, and the problems of low early strength, poor suitability for complex soft soil such as high salt and the like, lack of differential soil treatment process and insufficient performance stability caused by insufficient activity excitation of the conventional fly ash are solved. Disclosure of Invention In order to overcome the defects of the prior art, the invention aims to provide a fly ash-based soft soil curing agent and a preparation method and application thereof, so as to solve the technical problems of low early strength, poor suitability for complex soft soil such as high salt and the like, lack of differential soil treatment process and insufficient performance stability caused by insufficient activity excitation of the conventional fly ash. In order to achieve the above purpose, the invention is realized by adopting the following technical scheme: the invention discloses a preparation method of a fly ash-based soft soil curing agent, which comprises the following steps: Mixing and stirring the gradient activated fly ash, slag micropowder and metakaolin uniformly, adding quick-hardening silicate cement and sulphoaluminate cement, stirring uniformly for the second time, adding a potassium hydroxide-anhydrous sodium sulfate mixture, modified sodium silicate and tartaric acid, stirring uniformly for the third time, adding composite functional powder, stirring uniformly for the fourth time, detecting the mixing uniformity until the grain diameter variation coefficient is less than or equal to 5%, obtaining a mixed material, ball-milling the mixed material at low temper