A flowable soil curing membrane and method of making same

Abstract

The application discloses a flow state solidified soil curing film and a preparation method thereof, and relates to the technical field of building materials. The curing film comprises, from outside to inside, a reflective heat insulation layer and a water molecule slow-release layer. The raw materials of the reflective heat insulation layer comprise titanium dioxide nano powder, polyacrylate emulsion, fumed silica dispersion, dispersion aid, leveling agent and water. The raw materials of the water molecule slow-release layer comprise hydroxypropyl methyl cellulose, polyethylene glycol / bentonite intercalation compound, trisodium citrate, glycerol and water. The curing film can realize that the surface cracking rate of the flow state solidified soil is less than or equal to 5%, and the crack width is less than or equal to 0.1 mm. The curing film greatly solves the engineering pain points and difficult points of the flow state solidified soil, improves the appearance quality and durability of the flow state solidified soil, and improves the engineering quality and service life.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a fluidized solidified soil curing membrane and its preparation method. Background Technology

[0002] Fluidized solidified soil, a novel green building material, is composed of engineering waste or slurry, a curing agent, and water. It boasts advantages such as high fluidity, convenient construction, and low cost, and is widely used in engineering applications such as trenching, foundation pits, and roadbed backfilling. However, it suffers from cracking during its early hardening stage, especially under high temperatures, direct sunlight, or strong winds, where the cracking rate can reach 30% to 50%. This not only affects the appearance quality of the fluidized solidified soil but also reduces its strength and durability, ultimately impacting the overall quality and service life of the project.

[0003] The inherent mechanism of easy cracking of fluidized solidified soil mainly includes two aspects: (1) the surface evaporation rate is significantly higher than the internal bleeding rate of fluidized solidified soil, resulting in a large water evaporation gradient; (2) the surface temperature of fluidized solidified soil is 25-35℃ higher than that of the interior, resulting in a large temperature stress gradient. At present, strengthening maintenance is the main means to reduce the cracking rate of fluidized solidified soil, but the existing maintenance methods still have certain defects. For example, water covering maintenance will dilute the surface ion concentration of fluidized solidified soil, affecting the surface hardening speed and strength growth rate, and reducing its ability to resist plastic shrinkage cracks. The water retention of geotextile covering maintenance is poor, and it cannot suppress water evaporation. The surface humidity gradient of fluidized solidified soil is large, and the crack control effect is limited. The plastic film covering maintenance is easy to form a closed space, which leads to the accumulation of internal vapor pressure of fluidized solidified soil under high temperature and sun exposure, forming a high stress gradient that causes cracking. At the same time, condensation water impact is easy to form on the inner wall of the film, which aggravates the loss of surface fluidized solidified soil slurry. In addition, plastic film is easy to be damaged during use and needs to be replaced in time, which increases the maintenance cost and workload.

[0004] Currently, existing technologies lack targeted solutions to the aforementioned practical engineering challenges. Therefore, there is an urgent need to develop a special curing membrane for fluidized solidified soil that can dynamically regulate moisture migration and buffer temperature stress. Summary of the Invention

[0005] The purpose of this invention is to provide a curing membrane for fluidized solidified soil and its preparation method, thereby solving the problems existing in the prior art. The curing membrane of this invention consists of a reflective heat-insulating layer and a water molecule slow-release layer. Directly covering the surface of fluidized solidified soil, it can control the cracking rate to within 5% and the crack width to within 0.1 mm, greatly solving the engineering pain points and difficulties of easy cracking in fluidized solidified soil, and improving the curing efficiency and engineering quality of fluidized solidified soil.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] This invention provides a fluidized solidified soil curing membrane, comprising a reflective heat insulation layer and a water molecule slow-release layer;

[0008] The raw material composition of the reflective heat insulation layer, by mass percentage, is as follows: 20-30% titanium dioxide nanopowder, 35-40% polyacrylate emulsion, 12-18% fumed silica dispersion, 0.5-1.2% dispersant, 0.3-0.8% leveling agent, and the balance being water;

[0009] The raw material composition of the water molecule slow-release layer, by mass percentage, is as follows: 20-30% hydroxypropyl methylcellulose, 15-25% polyethylene glycol / bentonite intercalation complex, 0.5-1.5% trisodium citrate, 1-2.5% glycerol, and the balance being water.

[0010] Preferably, the thickness of the reflective heat insulation layer is 45-60 μm, and the thickness of the water molecule slow-release layer is 95-125 μm.

[0011] Preferably, the titanium dioxide nanopowder is rutile TiO2 synthesized by a hydrothermal method, with an average particle size of 30±2 nm, and is surface-treated with silane coupling agent KH-570, resulting in a surface hydroxyl density ≤1.5 hydroxyl groups / nm. 2 The dispersion index (PDI) is ≤0.25.

[0012] Preferably, the polyacrylate emulsion is a core-shell structured acrylate emulsion with a core layer Tg of 35°C, a shell layer Tg of 10°C, a carboxyl content of 1.2–1.8 wt%, and an emulsifier dosage of ≤1.5 wt% (reactive emulsifier).

[0013] The core layer is copolymerized from methyl methacrylate (MMA) and butyl acrylate (BA), while the shell layer is copolymerized from 2-ethylhexyl acrylate (2-EHA) and acrylic acid (AA).

[0014] Preferably, the fumed silica is oleophilic fumed silica (Aerosil R812) with a specific surface area of...

[0015] 260±30m 2 / g, after surface treatment with hexamethyldisilazane (HMDS), is pre-dispersed in PMA as a nano-sol with an average aggregate particle size ≤100nm.

[0016] Preferably, the dispersing agent is BYK-190 dispersing agent, with an active ingredient content of 40±2% and a viscosity reduction efficiency of ≥75%.

[0017] Preferably, the leveling agent is TEGO Glide 482 leveling agent, with 100% active ingredient, leveling time ≤3min (film thickness 50um), and thermal decomposition ≤1% (150℃, 2h).

[0018] As a further preferred embodiment of the present invention, the preparation method of the polyethylene glycol / bentonite intercalation composite includes the following steps:

[0019] Polyethylene glycol was heated and melted, then bentonite was added and mixed. An intercalation reaction was carried out at 75°C to obtain the polyethylene glycol / bentonite intercalation composite.

[0020] In the polyethylene glycol / bentonite intercalation composite, the mass ratio of polyethylene glycol to bentonite is 1:1 to 1:3.

[0021] Preferably, the viscosity of hydroxypropyl methylcellulose (HPMC) is 4000-6000 mPa·s (2% aqueous solution, 20°C), and the degree of substitution is: methoxy 28-30%, hydroxypropyl 7-12%.

[0022] Preferably, the bentonite is sodium-based bentonite with a montmorillonite content ≥90% and a cation exchange capacity (CEC).

[0023] ≥70mmol / 100g, interlayer spacing d(001)=1.2~1.5nm (original), after intercalation the interlayer spacing is expanded to 3.5~4.0nm.

[0024] Preferably, the polyethylene glycol (PEG) has a molecular weight of 4000-6000, a hydroxyl value ≤15mg KOH / g, and a moisture content of [missing information].

[0025] ≤0.5%.

[0026] Preferably, the trisodium citrate has a chemical purity of ≥99.5%, a particle size D50 of 45-55 μm, a pH of 7.8-8.2 for a 1% solution, and a dissolution time of ≤3 min (50°C water).

[0027] Preferably, the glycerin is USP grade and has a moisture content of ≤0.1%.

[0028] The present invention also provides a method for preparing a fluidized solidified soil curing membrane, preferably comprising the following steps:

[0029] Step 1: Preparation of the reflective heat insulation layer

[0030] S1: By mass percentage, 20-30% titanium dioxide nanopowder, 35-40% polyacrylate emulsion, 12-18% fumed silica dispersion, 0.5-1.2% dispersant, 0.3-0.8% leveling agent, and the balance being deionized water.

[0031] S2: Take all the titanium dioxide nanopowder and dispersing agent, add them to 40% of the total amount of polyacrylate emulsion, and mix them for 15±1 min using a high-speed disperser at a speed of 2000±100 rpm, while controlling the mixing temperature to be constant at 30℃, to obtain mixture A.

[0032] S3: Add the remaining polyacrylate emulsion to mixture A, and mix it using a high-speed disperser at a speed of 800-1000 rpm for 10 ± 0.5 min, while keeping the mixing temperature constant at 30℃, to obtain mixture B.

[0033] S4: Add all the fumed silica dispersion to mixture B at a rate of 5 mL / min, and mix for 20 ± 1 min using a high-speed disperser at a speed of 1500 ± 50 rpm, while keeping the mixing temperature constant at 30℃, to obtain mixture C.

[0034] S5: Add all the leveling agent to mixture C, mix with a high-speed disperser at a speed of 1000±50 rpm for 5±1 min, and control the mixing temperature to be constant at 30℃ to obtain mixture D.

[0035] S6: The mixture D is uniformly coated onto the release film at a coating speed of 20-25 m / min. The oven temperature gradient is set as follows: 60℃ (inlet) → 80℃ (main drying zone) → 70℃ (outlet), with an air velocity of 3-5 m / s and a coating thickness of 45-60 μm. After drying, the reflective heat insulation layer can be obtained by peeling. The peeling angle is 135°±5°, and the peeling speed is 0.5-1.0 m / min.

[0036] Preferably, the release film is a double-sided corona-treated PET release film with a silicone release agent coating thickness of 0.1-0.2 μm, a surface energy of 40±1 mN / m, and a heat shrinkage rate of ≤0.5% (80℃, 10min).

[0037] Step 2: Preparation of Water Molecule Release Layer

[0038] S1: By mass percentage, 20-30% hydroxypropyl methylcellulose (HPMC), 15-25% polyethylene glycol / bentonite intercalation complex, 0.5-1.5% trisodium citrate, 1-2.5% glycerol, and the balance being deionized water.

[0039] S2: Dry the bentonite at 80±5℃ for 2h, weigh it according to the mass ratio of bentonite:polyethylene glycol = 1:1 to 1:3 (preferably 1:2), heat the polyethylene glycol to 70±2℃ to melt it, add the bentonite powder, mix it in a high-speed mixer at 2500±100rpm for 30±1min, and then place it in a -0.09MPa vacuum oven for intercalation reaction at 75℃ for 24h to obtain polyethylene glycol / bentonite intercalation composite A.

[0040] S3: Add HPMC to deionized water at a rate of 5 g / min, control the water temperature at 50±5℃, stir at 300~400 rpm, and stir for 60±5 min to obtain transparent colloidal solution B.

[0041] S4: Add complex A to solution B in three portions, with a 5-minute interval between each portion. Maintain a temperature of 50±5℃, a stirring speed of 600~800rpm, and a stirring time of 30±2min to obtain a uniform slurry C.

[0042] S5: Add all of the trisodium citrate to slurry C, stir at 600-800 rpm for 5 ± 1 min to obtain a uniform slurry D.

[0043] S6: Add all the glycerol to slurry D, stir at 600-800 rpm for 10 ± 1 min to obtain a uniform slurry E.

[0044] S7: Let slurry E stand for 20±2 minutes, then automatically apply it to a polytetrafluoroethylene (PTFE) coated glass plate using a doctor blade. The doctor blade gap is 0.12±0.01 mm, the coating speed is 0.8-1.2 m / min, and the coating thickness is controlled to be 95~125 μm.

[0045] S8: Curing at 60±1℃, 40±5%RH and wind speed of 0.5-1.0m / s for 30±1min yields a water molecule slow-release layer.

[0046] Step 3: Applying the protective film

[0047] S1: Cut the reflective heat insulation layer obtained in step 1 and the water molecule slow-release layer obtained in step 2 to the same size.

[0048] S2: Align and overlap the cut reflective heat insulation layer with the water molecule slow-release layer (the reflective heat insulation layer is the outer layer, and the water molecule slow-release layer is the inner layer).

[0049] S3: Composite is performed using a double steel belt hot press composite machine. Preheating zone temperature: 50~60℃, hot press zone temperature: 110±2℃, pressure: 0.8±0.05MPa, hot press time: 30±1s, conveying speed: 2.0±0.1m / min.

[0050] S4: After natural cooling to room temperature, corona treatment is performed on the outer surface of the composite membrane (i.e., the surface of the reflective heat insulation layer). Power: 8kW, treatment speed: 1.5m / min, treatment intensity: 40~45mN / m (surface energy) to obtain the fluidized solidified soil curing membrane.

[0051] The present invention further provides the application of the above-mentioned fluidized solidified soil curing membrane in the curing of fluidized solidified soil.

[0052] This invention is based on the two core mechanisms of cracking in fluidized solidified soil (moisture evaporation gradient and temperature stress accumulation), and achieves precise control through a dual-layer functional structure. Its basic principle is as follows:

[0053] (1) The synergistic effect of the reflective insulation layer on temperature stress suppression.

[0054] Firstly, rutile titanium dioxide, as the main functional filler, has a high refractive index and extremely strong reflection and scattering capabilities for sunlight in the 400–2500 nm wavelength band (accounting for more than 95% of the total solar radiation energy), with a reflectivity ≥85%. Its nanoscale particle size (30±2 nm) ensures the best scattering effect in the visible light region, thereby directly reflecting most of the solar radiation energy back to the atmosphere, reducing heat accumulation from the source, and actually reducing the surface temperature of fluidized solidified soil by 16–23℃.

[0055] Secondly, after surface treatment, fumed silica forms a nanoporous aerogel network structure in the polymer matrix. Its inherent low thermal conductivity (≤0.03W / (m·K)) and the air trapped in the nanopores can effectively block heat transfer to the surface of the fluidized solidified soil, forming a highly efficient heat insulation barrier and inhibiting heat penetration from top to bottom.

[0056] Thirdly, the core-shell structured polyacrylate emulsion serves as the film-forming matrix and mechanical framework for the reflective heat insulation layer. The hard core (MMA / BA copolymer, Tg = 35℃) provides the coating with the necessary mechanical strength, wear resistance, and creep resistance, ensuring that the film is not easily damaged during construction and use, and can withstand certain wind loads. The soft shell (2-EHA / AA copolymer, Tg = 10℃) endows the coating with excellent flexibility and film-forming properties, enabling it to adapt to the minor deformations of the fluidized solidified soil base without cracking. The carboxyl groups (-COOH) in the shell not only provide emulsion stability but also act as coupling sites, tightly binding with the surfaces of fillers such as TiO2 and SiO2 through hydrogen bonds and other forces, significantly improving interfacial compatibility, preventing filler agglomeration and detachment, and ensuring the long-term stable function of the functional fillers.

[0057] Through the aforementioned synergistic mechanism, the designed reflective heat insulation layer reduces the temperature difference between the surface and interior of the fluidized solidified soil from 25–35℃ to ≤10℃, and reduces the temperature stress by about 70%, thereby effectively weakening the adverse effects of temperature stress on the cracking behavior of the fluidized solidified soil.

[0058] (2) The synergistic regulatory effect of the water molecule slow-release layer on the water gradient.

[0059] Firstly, while original sodium-based bentonite has a layered structure, its interlayer spacing is approximately 1.2–1.5 nm. Through a melt intercalation process, polyethylene glycol (PEG) molecular chains are inserted into the interlayer domains of bentonite, significantly expanding the interlayer spacing to 3.5–4.0 nm. This nanoscale space, expanded by PEG, constitutes a "nanoscale reservoir" and "channel" for storing and transporting water molecules. When the ambient humidity is >80%, water molecules in the environment are adsorbed into the interlayer domains of bentonite and the hydrophilic segments of PEG through capillary action and hydrogen bonding. The PEG chains hydrate and swell, further widening the interlayer spacing and locking a large amount of water within the nanoscale space. When the ambient humidity is <40%, the PEG segments dehydrate and shrink, narrowing the interlayer domains and "squeezing out" the stored water molecules, slowly releasing them to the surface of the fluidized solidified soil, maintaining its humidity. The design of this intercalation structure is one of the core elements of the water molecule slow-release layer design in this invention, because this intelligent response to humidity (hygroscopic absorption and release) depends entirely on the intercalation structure of PEG / bentonite. If no intercalation structure is formed, it is merely a physical mixture, where PEG is prone to migration and bentonite is prone to aggregation, making it impossible to form a stable, efficient and reversible nanoscale water storage unit.

[0060] Secondly, HPMC forms a hydrophilic three-dimensional network colloid, where numerous hydroxyl groups (-OH) adsorb and solidify a large amount of free water through hydrogen bonds, constituting a macroscopic "moisture reservoir." Its excellent water retention and high viscosity ensure that moisture does not evaporate rapidly, but rather is continuously supplied to the base layer at a slow rate (≥8h), suppressing the surface moisture evaporation rate of the fluidized solidified soil to 0.8 g / (m³). 2 ·h) and below.

[0061] Thirdly, trisodium citrate, as an environmentally friendly crosslinking agent, undergoes an esterification reaction between its carboxyl groups (-COOH) and the hydroxyl groups on the HPMC molecular chain during the heating and curing process, forming a stable covalent crosslinking network. This significantly improves the mechanical strength and wear resistance of the slow-release membrane in both dry and wet conditions, making it less prone to damage during construction and use. In addition, the crosslinking network limits the unlimited swelling of HPMC and bentonite when exposed to water, preventing the gel structure from being destroyed and ensuring the long-term stability of the structure and the durability of repeated moisture absorption and desorption cycles. At the same time, moderate crosslinking can regulate the diffusion rate of water molecules in the gel network, avoiding instantaneous release of water and achieving a smoother slow release.

[0062] Fourth, glycerol, as a small molecule plasticizer, forms hydrogen bonds with HPMC molecular chains through its hydroxyl groups, effectively weakening the hydrogen bonding between HPMC molecular chains and increasing the free volume and mobility between molecular chains. This makes the cured film soft and elastic, preventing it from becoming brittle and cracking due to drying or cross-linking, and ensuring that it can adhere well to the surface of the fluidized solidified soil. In addition, using glycerol as a plasticizer can effectively improve the rheology and film-forming properties of the slurry, which helps to form a dense, defect-free continuous film, which is the basis for achieving uniform moisture control.

[0063] Through the aforementioned synergistic mechanism, the designed water molecule slow-release layer reduces the ratio of surface water evaporation rate to internal water seepage rate of fluidized solidified soil from 3.2 to less than 1.1, thereby effectively weakening the adverse effects of the water evaporation gradient on the cracking behavior of fluidized solidified soil.

[0064] The present invention discloses the following technical effects:

[0065] This invention addresses the problem of easy cracking in the early hardening of fluidized solidified soil by providing a composite curing membrane. The curing membrane consists of a reflective heat insulation layer and a water molecule slow-release layer from the outside to the inside. It can achieve a surface cracking rate of ≤5% and a crack width of ≤0.1mm for fluidized solidified soil, which greatly solves the engineering pain point and difficulty of easy cracking of fluidized solidified soil, improves the appearance quality and durability of fluidized solidified soil, and improves the engineering quality and service life. Detailed Implementation

[0066] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0067] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0068] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0069] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0070] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0071] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0072] The embodiments and comparative examples provided in this invention were all completed under a uniform fluidized solidified soil mix ratio (the fluidized solidified soil was prepared from silty clay with a wet density of 1360 kg / m³). 3 The moisture content was 140%, the curing agent was commercially available P·O 42.5 cement, the curing agent dosage was 15%, the initial flowability of the fluidized solidified soil was 200mm, and the environmental conditions were fixed as follows: temperature 40±1℃, wind speed 6±0.5m / s, humidity 30±2%RH.

[0073] Example 1

[0074] The raw material composition of the reflective heat insulation layer, by weight percentage, is as follows:

[0075] 25% titanium dioxide nanopowder, 37% polyacrylate emulsion, 15% fumed silica dispersion, 0.8% dispersant, 0.5% leveling agent, and the balance being deionized water.

[0076] The raw material composition of the water molecule slow-release layer, by mass percentage, is as follows:

[0077] Hydroxypropyl methylcellulose (HPMC) 25%, polyethylene glycol / bentonite intercalation complex 20%, trisodium citrate 1.0%, glycerol 1.8%, deionized water balance.

[0078] 1. The performance indicators of each raw material in the reflective heat insulation layer are as follows:

[0079] Titanium dioxide nanopowder: rutile TiO2, synthesized via a hydrothermal method; average particle size 30 nm, surface treated with silane coupling agent KH-570; surface hydroxyl density 1.3 hydroxyl groups / nm. 2 The dispersion index (PDI) is 0.25.

[0080] Polyacrylate emulsion: core-shell structure, the core layer is copolymerized from MMA (methyl methacrylate) and BA (butyl acrylate), with a glass transition temperature Tg = 35℃; the shell layer is copolymerized from 2-EHA (isooctyl acrylate) and AA (acrylic acid), with a Tg = 10℃; carboxyl content 1.5wt%, and the emulsifier is a reactive emulsifier, used in an amount of 1.2wt%.

[0081] Fumed silica dispersion: The fumed silica used is oleophilic Aerosil R812 with a specific surface area of ​​260 m². 2 / g, after surface treatment with hexamethyldisilazane (HMDS), is pre-dispersed in PMA (propylene glycol methyl ether acetate) as a nano sol with an average aggregate particle size of 85nm.

[0082] Dispersant: BYK-190, active ingredient content 40%, viscosity reduction efficiency 86%.

[0083] Leveling agent: TEGO Glide 482, 100% active ingredient; leveling time of 2 min at a film thickness of 50 μm, and thermal decomposition of 0.2% at 150℃ for 2 h.

[0084] Deionized water: Free of impurities, conductivity ≤10μS / cm.

[0085] 2. The performance indicators of each raw material in the water molecule slow-release layer are as follows:

[0086] Hydroxypropyl methylcellulose (HPMC): A 2% aqueous solution has a viscosity of 5000 mPa·s at 20°C; Degree of substitution: methoxy 29%, hydroxypropyl 10%.

[0087] Polyethylene glycol / bentonite intercalation composite: Polyethylene glycol (PEG) molecular weight 6000, hydroxyl value 13 mg KOH / g, moisture content 0.3%; Bentonite is sodium-based bentonite, montmorillonite content 94%, cation exchange capacity (CEC).

[0088] 76 mmol / 100g, original interlayer spacing d(001) = 1.3 nm; the mass ratio of PEG to bentonite was 1:2, and the interlayer spacing increased to 3.8 nm after intercalation.

[0089] Trisodium citrate: chemical purity 99.5%, particle size D50 = 50 μm (±5 μm); 1% aqueous solution pH = 8.0 (±0.2), dissolution time in water at 50℃ is 1 min.

[0090] Glycerin: USP grade (United States Pharmacopeia grade), moisture content 0.06%.

[0091] Deionized water: Free of impurities, conductivity 9 μS / cm.

[0092] Preparation of fluidized solidified soil curing membrane:

[0093] (1) Preparation of reflective heat insulation layer:

[0094] S1: Take all the titanium dioxide nanopowder and BYK-190 dispersant and add them to 40% of the polyacrylate emulsion in the formula; use a high-speed disperser to mix for 15 minutes at a speed of 2000 rpm and a constant temperature of 30℃ to obtain mixture A.

[0095] S2: Add the remaining 60% of the polyacrylate emulsion to mixture A, keep the temperature of the high-speed disperser constant at 30°C, adjust the speed to 800 rpm, mix for 10 minutes to obtain mixture B.

[0096] S3: Slowly add 15% of the fumed silica dispersion to mixture B at a rate of 5 mL / min, maintain a constant temperature of 30°C, adjust the speed of the high-speed disperser to 1500 rpm, mix for 20 min, and obtain mixture C.

[0097] S4: Add TEGO Glide 482 leveling agent to mixture C, keep the temperature constant at 30℃, adjust the speed to 1000 rpm, mix for 5 minutes to obtain mixture D.

[0098] S5: Select a double-sided corona-treated PET release film (silicone release agent coating thickness 0.1μm, surface energy 40mN / m, heat shrinkage rate ≤0.5% at 80℃ for 10min) as the substrate, and uniformly coat the mixture D on the surface of the release film; the coating speed is controlled at 20m / min, and the coating thickness is 50μm; then send it into an oven for drying, the oven temperature gradient is set to 60℃ (inlet) → 80℃ (main drying zone) → 70℃ (outlet), and the wind speed is 3m / s; after drying, peel the film off the release film at a peel angle of 135° and a peel speed of 0.5m / min to obtain the reflective heat insulation layer.

[0099] (2) Preparation of water molecule slow-release layer:

[0100] S1: Preparation of polyethylene glycol / bentonite intercalation composite: Sodium bentonite was dried in an oven at 80°C for 2 hours. The dried bentonite and PEG6000 were weighed at a mass ratio of 1:2. The PEG6000 was heated to 70°C to completely melt it. Bentonite powder was added and the mixture was placed in a high-speed mixer and mixed at 2500 rpm for 30 minutes. The mixture was then transferred to a vacuum oven at -0.09 MPa and intercalated at 75°C for 24 hours to obtain the polyethylene glycol / bentonite intercalation composite (denoted as composite A).

[0101] S2: Preparation of HPMC colloidal solution: Heat deionized water to 50°C, slowly add 25% HPMC to the water at a rate of 5 g / min, and stir continuously at 300 rpm for 60 min until HPMC is completely dissolved to obtain a transparent colloidal solution (denoted as solution B).

[0102] S3: Add all of the complex A to solution B in three portions, with a 5-minute interval between each addition; keep the water temperature constant at 50°C, adjust the stirring speed to 600 rpm, and stir for 30 minutes to obtain a uniform slurry (denoted as slurry C).

[0103] S4: Add all 1.0% of trisodium citrate to slurry C, maintain the stirring speed at 600 rpm, and stir for 5 minutes to obtain slurry D.

[0104] S5: Add USP grade glycerin to slurry D, maintain stirring speed of 600 rpm, stir for 10 min to obtain a uniform slurry (denoted as slurry E).

[0105] S6: Let slurry E stand for 20 minutes to eliminate air bubbles, and then use an automatic doctor blade casting device to coat it onto a polytetrafluoroethylene (PTFE) coated glass plate; the doctor blade gap is set to 0.12±0.01mm, the coating speed is 0.8m / min, and the coating thickness is controlled to 100μm.

[0106] S7: Place the coated glass plate into a curing environment (temperature 60℃, relative humidity 40% RH, wind speed 0.5m / s) and cure for 30 minutes. After peeling off the glass plate, a water molecule slow-release layer is obtained.

[0107] (3) Preparation of fluidized solidified soil curing membrane

[0108] a. Pretreatment: The above-prepared reflective heat insulation layer and water molecule slow-release layer are both cut into the same size with a width of 2m and a length of 5m.

[0109] b. Overlapping: The reflective heat insulation layer is used as the outer layer and the water molecule slow-release layer is used as the inner layer. After aligning the edges, they are tightly overlapped.

[0110] c. Hot pressing composite: The composite process is carried out using a double steel belt hot pressing composite machine. The equipment parameters are set as follows: preheating zone temperature 50℃, hot pressing zone temperature 110℃, hot pressing pressure 0.8MPa, hot pressing time 30s, and conveying speed 2.0m / min.

[0111] d. Corona treatment: The composite membrane is naturally cooled to room temperature, and the outer surface of the reflective heat insulation layer is subjected to corona treatment. The corona treatment parameters are: power 8kW, treatment speed 1.5m / min, and the surface energy after treatment is controlled at 40mN / m. Finally, the fluidized solidified soil curing membrane of this embodiment is obtained.

[0112] Example 2

[0113] The raw material composition of the reflective heat insulation layer, by weight percentage, is as follows:

[0114] 20% titanium dioxide nanopowder, 35% polyacrylate emulsion, 12% fumed silica dispersion, 0.5% dispersant, 0.3% leveling agent, and the balance being deionized water.

[0115] The raw material composition of the water molecule slow-release layer, by mass percentage, is as follows:

[0116] Hydroxypropyl methylcellulose (HPMC) 20%, polyethylene glycol / bentonite intercalation complex 15%, trisodium citrate 0.5%, glycerol 1%, deionized water balance.

[0117] The performance indicators of the raw materials for the reflective heat insulation layer and the water molecule slow-release layer are the same as in Example 1.

[0118] The preparation of the fluidized solidified soil curing membrane is the same as in Example 1.

[0119] Example 3

[0120] The raw material composition of the reflective heat insulation layer, by weight percentage, is as follows:

[0121] 30% titanium dioxide nanopowder, 40% polyacrylate emulsion, 18% fumed silica dispersion, 1.2% dispersant, 0.8% leveling agent, and the balance being deionized water.

[0122] The raw material composition of the water molecule slow-release layer, by mass percentage, is as follows:

[0123] Hydroxypropyl methylcellulose (HPMC) 30%, polyethylene glycol / bentonite intercalation complex 25%, trisodium citrate 1.5%, glycerin 2.5%, deionized water balance.

[0124] The performance indicators of the raw materials for the reflective heat insulation layer and the water molecule slow-release layer are the same as in Example 1.

[0125] The preparation of the fluidized solidified soil curing membrane is the same as in Example 1.

[0126] Example of effect verification:

[0127] Comparative Example 1

[0128] A 0.1mm PE plastic film is used for full-coverage curing.

[0129] Comparative Example 2

[0130] Using 400g / m 2 Polyester geotextile full-coverage maintenance method.

[0131] Comparative Example 3

[0132] The surface is continuously covered with water (5mm water depth) for curing.

[0133] Comparative Example 4

[0134] Full coverage maintenance was performed using only the water molecule slow-release monolayer membrane prepared in Example 1.

[0135] Comparative Example 5

[0136] Full coverage maintenance was performed using only the single-layer reflective heat insulation film prepared in Example 1.

[0137] Comparative Example 6

[0138] Same as Example 1, except that an equal amount of sodium-based bentonite is used instead of polyethylene glycol / bentonite intercalation compound.

[0139] Referring to GB / T 50082 "Standard for Test Methods of Long-Term Performance and Durability of Concrete", the cracking (cracking rate, maximum crack width) and water loss rate of the fluidized solidified soil of Examples 1-3 (composite curing membrane of the present invention) and Comparative Examples 1-5 (traditional curing method and single-layer membrane curing) were observed and recorded during the 3-day curing period. The results are shown in Table 1.

[0140] Table 1

[0141] Example 1 1.2 0.04 4.5 Example 2 4.8 0.09 7.6 Example 3 3.5 0.06 7.3 Comparative Example 1 37.3 1.3 36.5 Comparative Example 2 48.8 2.1 64.1 Comparative Example 3 26.4 0.8 - Comparative Example 4 17.6 0.15 21.2 Comparative Example 5 23.1 0.24 18.5 Comparative Example 6 10.5 0.12 13.1

[0142] The test data from Examples 1 to 3 show that the double-layer composite curing membrane provided by the present invention has excellent curing effect on fluidized solidified soil: the cracking rate is less than 5%, the maximum crack width is less than 0.1 mm, and the water loss rate after 72 hours is less than 8%, which can effectively solve the problem of easy cracking in the early hardening stage of fluidized solidified soil.

[0143] Comparative Examples 1-3 of traditional curing methods: Comparative Example 1, using 0.1mm PE plastic film for full coverage curing, 400g / m 2 Comparative Example 2, which involved full coverage curing with polyester geotextile, and Comparative Example 3, which involved continuous surface water covering (5 mm water depth), both failed to effectively control surface cracking of the fluidized solidified soil. The cracking rates of the three examples ranged from 26.4% to 48.8%, with the maximum crack width ranging from 0.8 to 2.1 mm. Furthermore, except for Comparative Example 3, which involved water covering, the 72-hour water loss rates of Comparative Example 1 (PE membrane) and Comparative Example 2 (geotextile) remained at a relatively high level of 36.5% to 64.1%, fully demonstrating that the crack control effect of traditional curing methods on fluidized solidified soil is far inferior to that of the crack-resistant composite curing membrane of this invention.

[0144] Comparing Example 1 with Comparative Example 4 (cured using only a single-layer water-molecule slow-release membrane) and Comparative Example 5 (cured using only a single-layer reflective heat-insulating membrane), it is evident that the curing effect of using any single-layer membrane alone is significantly inferior to the composite curing membrane of this invention. The single-layer reflective heat-insulating membrane and the water-molecule slow-release membrane provided by this invention have functional mutual support, exhibiting excellent curing effects for fluidized solidified soil. Comparing Example 1 with Comparative Example 6, it is evident that the beneficial effects of the polyethylene glycol / bentonite intercalation are significant and indispensable.

[0145] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A fluidized solidified soil curing membrane, characterized in that, Includes a reflective heat insulation layer and a water molecule slow-release layer; The raw material composition of the reflective heat insulation layer, by mass percentage, is as follows: 20-30% titanium dioxide nanopowder, 35-40% polyacrylate emulsion, 12-18% fumed silica dispersion, 0.5-1.2% dispersant, 0.3-0.8% leveling agent, and the balance being water; The raw material composition of the water molecule slow-release layer, by mass percentage, is as follows: 20-30% hydroxypropyl methylcellulose, 15-25% polyethylene glycol / bentonite intercalation complex, 0.5-1.5% trisodium citrate, 1-2.5% glycerol, and the balance being water; The titanium dioxide nanopowder is rutile titanium dioxide nanopowder and has been surface-treated with silane coupling agent KH-570. The polyacrylate emulsion is a core-shell structured acrylate emulsion, wherein the core layer Tg=35℃ and the shell layer Tg=10℃; the carboxyl content of the polyacrylate emulsion is 1.2~1.8wt%, and the amount of reactive emulsifier is ≤1.5wt%.

2. The fluidized solidified soil curing membrane according to claim 1, characterized in that, In the polyethylene glycol / bentonite intercalation composite, the mass ratio of polyethylene glycol to bentonite is 1:1 to 1:

3.

3. The fluidized solidified soil curing membrane according to claim 1, characterized in that, The core-shell structured acrylate emulsion has a core layer obtained by copolymerizing methyl methacrylate and butyl acrylate, and a shell layer obtained by copolymerizing 2-ethylhexyl acrylate and acrylic acid.

4. The fluidized solidified soil curing membrane according to claim 1, characterized in that, The fumed silica dispersion is a nano-sol obtained by dispersing oleophilic fumed silica with hexamethyldisilazane surface treatment in a solvent.

5. The fluidized solidified soil curing membrane according to claim 1, characterized in that, The preparation method of the polyethylene glycol / bentonite intercalation composite includes the following steps: Polyethylene glycol was heated and melted, then bentonite was added and mixed. An intercalation reaction was carried out at 75°C to obtain the polyethylene glycol / bentonite intercalation composite.

6. The fluidized solidified soil curing membrane according to claim 5, characterized in that, The polyethylene glycol has a molecular weight of 4000-6000; the bentonite is sodium-based bentonite.

7. The method for preparing the fluidized solidified soil curing membrane according to any one of claims 1-6, characterized in that, Includes the following steps: The raw materials of the reflective heat insulation layer are mixed according to the mass percentage, and then the resulting mixture is subjected to film forming treatment to obtain the reflective heat insulation layer; The raw materials for the water molecule slow-release layer are mixed according to a mass percentage, and then the resulting mixture is subjected to a film-forming treatment to obtain the water molecule slow-release layer. The reflective heat insulation layer and the water molecule slow-release layer are hot-pressed together, and then corona treatment is performed to obtain the fluidized solidified soil curing membrane.

8. The preparation method according to claim 7, characterized in that, The hot-pressing composite temperature is 110±2℃ and the pressure is 0.8±0.05MPa; the power of the corona treatment is 8kW.

9. The application of the fluidized solidified soil curing membrane as described in any one of claims 1-6 in the curing of fluidized solidified soil.