Preparation method of high-performance roadbed materials based on fly ash modification

Abstract

This invention relates to the field of marine engineering subgrade material preparation technology, and discloses a method for preparing high-performance subgrade materials based on fly ash modification. The method includes: spraying atomized activator onto the surface of fly ash particles, using inorganic acid to etch micro-pits on the surface and depositing mineral salts in situ; mixing activated fly ash with aggregates and an alkaline activator to prepare a subgrade mixture; applying high-frequency vibration pressure during compaction to inject the activating force into the micro-pits; and utilizing the osmotic pressure difference generated by the dissolution of mineral salts to drive the hydration products to grow outward from the micro-pits. This invention, through the concentration gradient generated by the mineral salt enrichment layer, causes the hydration products to form a reverse-growth interwoven structure within the pores, achieving a shift from passive barrier to active sealing defense, thereby improving the material's mechanical anchoring strength and resistance to ion penetration in high-salt marine environments.

Description

Technical Field

[0001] This invention relates to a method for preparing high-performance roadbed materials based on fly ash modification, belonging to the field of marine engineering roadbed material preparation technology. Background Technology

[0002] Current conventional technical solutions typically employ strong alkaline chemical activation of the fly ash particle surface, triggering a pozzolanic reaction that produces hydrated calcium silicate gel. However, in marine environments, roadbed materials face the combined effects of varying salinity penetration and tidal reciprocating loads. This strong surface activation method exhibits physical limitations. The excessively rapid early hydration reaction rate leads to the rapid accumulation of products on the fly ash particle surface, forming a dense, hard shell that blocks the migration of moisture and activating components to the particle core. This results in surface passivation of the fly ash particles, limiting the subsequent strength growth of the material.

[0003] While increasing the amount of cementitious materials or adding nano-mineral powder can fill pores, it cannot change the randomly generated spatial topology of hydration products. Under dynamic humidity conditions, the interconnected pores inside the material still act as carriers for chloride ion penetration, and the microcracks in the interface transition zone caused by modulus mismatch continue to serve as erosion channels. Improving the static filling of multi-focused material components ignores the control of crystal growth kinetics and the dynamic balance of micro-region energy levels. For example, Chinese invention patent CN120328970A discloses a penetrating crystalline waterproof material with ultra-high osmotic pressure resistance. The use of hydroxyl-modified molecular sieves to capture free calcium and induce network crystal formation is a method that utilizes the water-releasing properties of molecular sieves. However, this uniform crystallization mode, which relies on the molecular sieve framework, lacks a dynamic response mechanism for ion concentration gradients when facing extreme high-salt pulse infiltration impacts. It cannot overcome the hard-shell effect of fly ash particles, which is solid on the outside and hollow on the inside, and it is difficult to form deep mechanical anchoring at the cementation interface. The roadbed is prone to fatigue damage under dynamic tidal loads. Therefore, it is crucial to find a modification method to change the crystallization starting point and realize the directional transport of hydration products, and to establish a defense system with active sealing capabilities to ensure the long service life of marine engineering roadbeds.

[0004] Therefore, the technical problem to be solved by this invention is how to induce the directional growth of hydration products through micro-region interface energy level regulation and construct an osmotic pressure barrier with dynamic interception capability to solve the problems of ion erosion and insufficient structural toughness in the long-term service of marine engineering roadbeds. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A method for preparing high-performance roadbed materials based on fly ash modification, comprising the following steps: Step S101: Spray an atomizing activator onto the surface of fly ash particles to perform surface activation treatment. The atomizing activator includes 0.5% to 1.2% by mass of halogen acid and a solute composed of highly soluble mineral salts. The halogen acid is used to etch the surface of the fly ash particles to form micron-level etched pits, and the highly soluble mineral salts are deposited in situ within the etched pits to construct a mineral salt enrichment layer with a concentration gradient. Step S102: The surface-activated fly ash particles, aggregates, alkaline activator and mixing water are mixed and stirred according to a preset ratio to obtain the roadbed mixture. Step S103: Spread the roadbed mixture on the roadbed working surface. During the compaction operation, apply high-frequency vibration energy to the roadbed mixture using a vibratory roller. Use high-frequency vibration energy to reduce the wetting resistance of the fly ash particles and press the liquid phase alkaline activation component in the roadbed mixture into the etched micro-pits. In step S104, the fly ash particles undergo a hydration reaction under the action of an alkaline activator. The osmotic pressure difference generated after the mineral salt enrichment layer dissolves serves as a power source, driving the generated hydration products to crystallize and grow directionally from the inside of the etched micro-pits to the external interconnected pores, forming an interface with a mechanical anchoring structure between the fly ash particles and the aggregate.

[0006] Preferably, the process conditions for surface activation treatment in step S101 are as follows: the atomized droplet size of the atomizing activator is controlled to be 10 μm to 50 μm, and the mass ratio of the atomizing activator to fly ash particles is controlled to be 0.02 to 0.05, so as to generate localized differential etching by utilizing the discontinuous liquid film formed by the atomized droplets on the surface of the fly ash particles.

[0007] Preferably, in step S101, the average depth of the etched micro-pits is 0.5 μm to 2.5 μm, and the anchoring mass of the mineral salt per unit area in the mineral salt enrichment layer is 15 g / m². 2 Up to 40g / m 2 .

[0008] Preferably, the operating parameters for applying high-frequency vibration energy in step S103 are: controlling the vibration frequency to be 25Hz to 50Hz, controlling the amplitude to be 0.6mm to 1.5mm, and controlling the number of compaction passes to be 4 to 8.

[0009] Preferably, the quantitative characterization formula for the osmotic pressure difference in step S104 is as follows: ,in, This is the calculated value of the osmotic pressure difference, in MPa; Van der Hoff factor for highly soluble mineral salts; This refers to the molar concentration of highly soluble mineral salts within the etched micro-pits. It is the ideal gas constant; The thermodynamic temperature for maintaining the environment; by setting the initial addition amount of highly soluble mineral salts, the calculated... The value is not less than 1.5 times the osmotic pressure of the preset external salt water erosion environment.

[0010] Preferably, in step S102, the alkaline activator is selected from at least one of sodium hydroxide, sodium silicate, and sodium aluminate, and the added mass of the alkaline activator is 4% to 8% of the mass of fly ash particles, and the water-cement ratio in the roadbed mixture is 0.28 to 0.35.

[0011] Preferably, the following mixing process is used in step S102: dry mixing the aggregate with the surface-activated fly ash particles for 60s to 90s, adding a mixture of mixing water and alkaline activator, and stirring for 120s to 180s at a speed of 40r / min to 60r / min.

[0012] Preferably, step S104 further includes spraying a curing sealant on the paved subgrade surface to seal the pores on the subgrade surface, thereby maintaining the moisture gradient inside the subgrade mixture and guiding the hydration products to form an interwoven structure along the pore channels.

[0013] Preferably, the hydration product in the mechanical anchoring structure is calcium silicate gel whisker, with an average aspect ratio of not less than 30, and a physical shielding barrier is formed by the cross-stacking of whiskers at the opening of the etched micro-pits.

[0014] Preferably, in step S102, a polarity regulating component with potential modification function is introduced. The polarity regulating component is a cationic polymer containing quaternary ammonium salt groups. The polarity regulating component is used to adjust the charge distribution on the surface of fly ash particles during the hydration reaction to enhance the crystallization motive force for the hydration product to extend and grow into external pores.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. In the preparation of high-performance roadbed materials, atomized activators are used to pretreat the surface of fly ash, forming nanoscale micro-etched regions with high surface energy on the surface of fly ash particles. Combined with the in-situ dissolution of solid excitation components after the addition of mixing water, the conventional uniform excitation mode of fly ash is changed, so that the hydration reaction is preferentially triggered in the micro-etched region and grows in a directional radial pattern to connect the pores to the outside, forming a discontinuous interface with topological closure characteristics. This transforms the bonding force between fly ash and aggregate from intermolecular adsorption to deep mechanical anchoring, thereby improving the structural stability and anti-stripping ability of roadbed materials under marine environmental loads.

[0016] 2. By utilizing the pressure pulse generated during the compaction operation after roadbed paving, the capillary resistance of the micropores on the surface of fly ash particles is overcome, and the dissolved solid activating components are forcibly pumped to the depths of the micro-etched area. This achieves a qualitative change from the surface barrier of the particles to the internal reinforcement structure of the particles, causing the formation of dense columnar bodies of hydration products inside the fly ash particles. Through the cross-scale coupling of physical mechanical energy and chemical reaction driving force, the quasi-elastic recovery capacity of the roadbed under extreme heavy loads is improved, and the surface passivation problem of the fly ash system under thick paving conditions is solved.

[0017] 3. By pre-planting highly hydrophilic mineral salt cores in the micro-etching area, a chemical potential gradient induction layer is established in the fly ash micro-region. The local high osmotic pressure generated by the dissolution of the salt cores generates a reverse material transport response when the external corrosive medium penetrates through the capillary channel. This drives the calcium silicate gel to diffusely grow in the direction of the incoming flow of the corrosive medium, upgrading the traditional passive physical barrier to an active infiltration seal. This enables the roadbed material to have an adaptive defense capability against variable salinity environments, and fundamentally cuts off the carrier channels for chloride ion migration. Attached Figure Description

[0018] Figure 1 This is a process flow diagram for preparing high-performance roadbed materials modified with fly ash according to the present invention. Figure 2 This is a time-series evolution diagram of the microscopic interaction mechanism and directional growth of hydration products in the roadbed material of this invention. Detailed Implementation

[0019] To make the methods, technical objectives, solutions, and effects claimed in this invention clearer, the invention will be described in detail below with reference to specific embodiments. The following embodiments are intended to explain and illustrate the invention, and are not intended to limit the scope of protection of the invention.

[0020] A method for preparing high-performance roadbed materials based on fly ash modification mainly involves four stages: surface activation, mixing and stirring, high-frequency vibration compaction, and osmotic pressure-induced crystallization. Utilizing the local chemical potential gradient on the particle surface, hydration products are driven to directionally fill pores, transforming the physical accumulation between fly ash particles and aggregates into deep mechanical anchoring. Addressing the technical problem of fly ash particles easily accumulating hydration products to form a dense, hard shell, blocking the migration of moisture and activating components to the particle core, this invention employs a surface activation method. The fly ash is placed in a dry powder state, and an atomized activator is sprayed onto the surface of the fly ash particles using a spray method. The atomized activator comprises [amount missing] by mass percentage. to The solutes, consisting of halogenated acids and highly soluble mineral salts, control the atomized droplet size of the atomizing activator to be... m to m, controlling the mass ratio of atomizing activator to fly ash particles. to The method utilizes atomized droplets to form a discontinuous liquid film on the surface of fly ash particles. Halogenated acids then induce localized, differentiated etching on the fly ash particle surface, resulting in an average depth of [missing information]. m to Etched micropits of m in size allow for in-situ deposition of highly soluble mineral salts within the pits, forming a mineral salt enrichment layer with a concentration gradient. The anchoring mass of the mineral salts per unit area in this enrichment layer is [value missing]. to To ensure sufficient chemical potential traps are established within the micron-sized etched micropits, a highly soluble mineral salt is selected from at least one of calcium chloride, magnesium chloride, calcium nitrate, or magnesium nitrate. The solubility at that time is not less than Water, through in-situ deposition of mineral salts during the halogen acid etching process, establishes an initial molar concentration at the bottom of the etched micro-pits. Not less than The solute enrichment microenvironment was determined by mass percentage. to And the mass ratio of hydrochloric acid to hydrofluoric acid is A mixed acid solution was used as a solvent to prepare the atomization activator. The mineral salt was dissolved in the solvent, and the ionic strength was monitored and maintained. conductivity at ℃ mS / cm to In the mS / cm range, the polarity-adjusting component potential reversal point is determined by the presence of... The composition was determined by alkaline titration of simulated pore liquid and recorded using a potentiometer. Potential changes with pH value Rise to The trajectory was analyzed and the critical pH value from positive to negative was extracted, based on the initial conductivity of the mixing water at the site. Calculate the background ion compensation coefficient and adjust the alkaline activator dosage to stabilize the pH during the accelerated hydration period of the subgrade mixture. This allows the calcium silicate gel whiskers to extend outwards into the pores, avoiding the openings of the etched micro-pits.

[0021] During the mixing stage, the activated fly ash particles, aggregates, alkaline activator, polarity adjusting component, expansion component, and mixing water are mixed and stirred. The alkaline activator is selected from at least one of sodium hydroxide, sodium silicate, or sodium aluminate, and its added mass is equal to the mass of the fly ash particles. to The water-cement ratio in the roadbed mixture is to The polarity regulating component is a strong cationic polymer containing quaternary ammonium salt groups. This polarity regulating component is polydimethyldiallyl ammonium chloride, with a weight-average molecular weight range of 50,000 to 100,000. In an environment with a pH value below 11.8, this polymer exhibits strong positive charge due to the charge saturation state of the quaternary ammonium salt cationic groups on the molecular chain. When the hydration reaction enters the accelerated phase, causing the environmental pH value to rise to the critical point of 11.8, the molecular chain undergoes side group deprotonation and chain segment conformation collapse, resulting in a rapid decay and reversal of its surface electrokinetic potential from positive 25.6 mV to negative 18.2 mV. This potential reversal characteristic ensures the generation of electrostatic repulsion at the opening of the micro-pits, inhibiting the aggregation of negatively charged hydration product precursors at the pit opening, thereby forcing whiskers to extend and grow into external pores. Utilizing the charge adsorption layer formed by the polymer on the fly ash surface, electrostatic attraction is formed with the negatively charged hydration precursors, and in the system... The value increased to After reaching the critical point, the surface potential reverses from positive to negative through the side-group deprotonation effect. Utilizing the repulsive force between like charges, the generated hydration product whiskers are driven to extend directionally into the depths of the aggregate pores, avoiding the openings of the etched micro-pits. The expansion component is light-burned magnesium oxide micropowder with a hydrophobic coating layer. This hydrophobic coating layer is made of magnesium stearate with a melting point of 60℃ and is uniformly coated onto the surface of the light-burned magnesium oxide particles using a thermal spraying process. The calibration method for the hydrophobic hysteresis coefficient is as follows: A saturated calcium hydroxide solution with a pH of 12.5 is prepared in a laboratory environment. Light-burned magnesium oxide powder with different coating ratios is added to the solution, and the conductivity of the solution is monitored using a conductivity meter. The curve of conductivity change over time was recorded; the inflection point time when the conductivity changed from a steady state to a rapidly rising state was recorded, which is the hydration trigger time; the proportional relationship between the magnesium stearate coating ratio and the trigger time was determined by linear regression analysis, thereby obtaining the hydrophobic time lag coefficient of this batch of materials; based on the energy attenuation gradient at different depths of the subgrade, the required delayed start time was calculated by referring to a table, and the expansion component with the corresponding coating ratio was matched accordingly; the micro-area expansion force generated by the controlled hydration of lightly calcined magnesium oxide in the later stage of curing was used to compensate for the energy loss of mechanical compaction; the hydration trigger time was determined to address the risk of insufficient bottom layer density caused by the attenuation of mechanical vibration energy with increasing depth during the paving of thick marine subgrades. Mass fraction of hydrophobic coating Satisfying linear mapping relationship ,in, Hydration trigger time, in units of , The hydrophobic time delay coefficient has a range of values. to , This represents the mass fraction of the coating agent, in units of... By pre-measuring the energy attenuation gradient at different depths of the roadbed, the required delayed start-up time is calculated, and the corresponding time is determined in reverse. To compensate for energy loss during compaction, the controlled hydration of lightly calcined magnesium oxide in the later stages of curing generates micro-area expansion force. The following mixing process is employed: Aggregate is dry-mixed with activated fly ash particles. to Add the mixture of mixing water and alkaline activator, and rotate at a speed of [speed value missing]. to Stirring under the conditions to After the roadbed mixture is spread on the working surface, a vibratory roller is used to apply high-frequency vibration energy to overcome the wetting resistance of the fly ash particles. The compaction operation parameters are set as follows: vibration frequency is... to The amplitude is to The number of compaction passes is Pervading The high-frequency vibration can force the liquid-phase alkaline excitation components in the roadbed mixture into the etched micro-pits.

[0022] During the curing stage, fly ash particles undergo hydration reactions. Utilizing the osmotic pressure difference generated by the dissolution of the mineral salt enrichment layer as a driving force, the resulting hydration products are directionally crystallized and grown from the interior of the etched micro-pits towards the external interconnected pores. The quantitative characterization formula for the osmotic pressure difference is as follows: ,in, This is the calculated value of the osmotic pressure difference, in units of... , Van der Hoff factor for highly soluble mineral salts, This refers to the molar concentration of highly soluble mineral salts within the etched micro-pits. Let be the ideal gas constant. To maintain the thermodynamic temperature of the environment, the initial addition amount of highly soluble mineral salt is set to achieve the calculated... The value is greater than the osmotic pressure of the external saltwater erosion environment. The polarity of the components is adjusted according to the system. The potential reversal caused by the increase in value repels the accumulation of hydration products at the opening of the etched micro-pits, allowing the hydration products to grow deeper into the pores between the aggregates, forming an average aspect ratio greater than [missing value]. The calcium silicate gel whiskers form a mechanical anchoring structure between fly ash particles and aggregates. The expanding components generate micro-area expansion forces in the mechanical pressure attenuation region, compensating for compaction energy transfer losses and guiding hydration products to form an interwoven structure along pore channels. The mass percentage of these whiskers is sprayed onto the roadbed surface. Modified waterborne epoxy curing sealant, with spray pressure controlled at... to , forming a thickness of The water-blocking film layer maintains the moisture gradient inside the roadbed mixture, forming a protective barrier with a spatially closed structure; the hydration trigger time of the expansion component... With the mass fraction of the coating agent The mapping relationship was determined by isothermal microcalorimetry, measuring different... The hydration exothermic rate curve of lightly calcined magnesium oxide was analyzed, and the time of rate abrupt change was extracted. A linear regression model was then established to determine the hydrophobic time delay coefficient. Combined with the thickness of the roadbed paving The corresponding vibration energy attenuation gradient is set for the expansion component of the bottom mixture. The value is determined by compensating for the longitudinal loss of mechanical compaction energy through the controlled hydration micro-zone expansion force of lightly calcined magnesium oxide, and the mass fraction of the coating agent. According to the formula The acid-base buffering capacity of fly ash surface was calculated and determined by titration, based on the volume of standard acid solution consumed per unit mass. Adjust the spray volume of the atomizing activator to maintain the average depth of the etched micro-pits at a certain level. m.

[0023] Example 1: In the construction scenario of saline-alkali fill roadbed in the South China Sea, this work condition faces erosion from high-salinity groundwater and alternating tidal infiltration. Conventional fly ash roadbed materials, due to the dense, hard shell formed by surface hydration, fail to activate internal particles with alkaline activators. Furthermore, the randomly distributed hydration product pathways within cannot block the capillary migration of chloride ions, resulting in chemical erosion and structural collapse of the roadbed. In this application scenario, a specific surface area of ​​[missing information] is used... In the surface activation treatment of fly ash particles, the mass percentage of halogen acids in the atomizing activator is set to be [value missing]. And the dissolved mass percentage is Highly soluble mineral salts, controlling the average droplet size of the atomized liquid to be [value missing]. m, according to A liquid-to-powder ratio is sprayed onto the surface of fly ash particles, utilizing the non-uniform etching of the fly ash surface by halide acids to produce an average depth of [missing information]. The etched micro-pits, measuring m in size, allow highly soluble mineral salts to precipitate within them as water evaporates, resulting in an anchoring mass per unit area of ​​m. Mineral salt enrichment layer.

[0024] During the mixing process, the activated fly ash particles are mixed with particles of a diameter of [missing information]. to The crushed stone aggregate is mixed, and the added mass is equal to the mass of fly ash. Sodium silicate is used as an alkaline activator, and is incorporated into the mixture at a mass percentage of [missing information]. The cationic polymer is used as a polarity regulating component to control the water-cement ratio of the roadbed mixture. ,exist Stirring at speed The alkaline activator adsorbs onto the non-etched areas of the fly ash surface. The mixture is then spread and compacted using a vibratory roller, with the vibration frequency set to [value missing]. And the amplitude is Under this high-frequency vibration, the liquid medium overcomes interfacial tension and penetrates into the etched micro-pits, contacting the pre-placed mineral salts. During the curing stage, fly ash particles undergo a hydration reaction under the action of an alkaline activator, utilizing the osmotic pressure difference generated by the dissolution of the mineral salt enrichment layer. Driven crystal growth, specifically, according to the formula The calculated osmotic pressure difference within the micro-region is as follows: ,in, This is the calculated value of the osmotic pressure difference. Van der Hoff factor for highly soluble mineral salts, This refers to the molar concentration of highly soluble mineral salts within the etched micro-pits. Let be the ideal gas constant. To maintain the thermodynamic temperature of the environment, under this pressure difference, the generated hydration products, under the potential repulsion of the polarity-regulating components, grow radially from the pit into the interconnected pores, producing an average aspect ratio of... The calcium silicate gel whiskers penetrate the micropores on the surface of the crushed stone aggregate to form an anchoring layer. Under this preparation method, the roadbed material... The Queen's compressive strength is ,exist Continuous soaking in sodium chloride solution of high concentration After that, its chloride ion penetration depth was Due to the chemical potential difference induced by the internal structure, the crystals are arranged in an ordered manner, and the roadbed structure has a steady-state characteristic of actively blocking the interconnected pores in the high-salt marine environment.

[0025] Example 2: Verifying the influence of surface activation process on the properties of roadbed materials under simulated high-salt marine engineering environment. The test platform includes a temperature control accuracy better than [previous standard]. The constant temperature and humidity curing system and the load resolution are The universal testing machine uses raw data collected through a physical experimental platform. The core parameter, the sampling period, is determined by the rate of change of the pressure sensor's output signal. When the signal slope exceeds... At that time, the sampling frequency was changed from Automatically switch to To capture the characteristic points of the material's compressive yielding stage, the experimental environment was superimposed with a salinity fluctuation period of... The dynamic concentration gradient perturbation is used to characterize the interference of real tidal conditions on the ion distribution inside the roadbed.

[0026] Roadbed material samples were prepared according to the following procedures. The mass fraction is in a dry powder state and has a specific surface area of Fly ash particles are placed in a sealed spray chamber and, according to The liquid powder mass ratio to the median particle size of the spray is The atomizing activator m causes a discontinuous liquid film to form on the surface of fly ash particles; the activated fly ash particles are then mixed with... The mass of crushed stone aggregate is dry-mixed in a forced mixer. ,according to The water-cement ratio added contains fly ash by mass. The mixing water and mass percentage of sodium silicate are as follows: Cationic polymers; at a rotation speed of wet mixing under the conditions The subgrade mixture is obtained, and the subgrade mixture is loaded into... A cube test mold was subjected to a vibration table with a frequency of [frequency value missing]. And the amplitude is High-frequency vibration energy compaction Once, finally at a temperature of And the relative humidity is not lower than Maintenance in an environment until Age; the experimental design included an experimental group, a partially missing control group, and an out-of-range control group. The experimental group used the process parameters described in the aforementioned specific implementation method. Control group 1 removed the high-frequency vibration compaction step, and control group 2 set the mass percentage of halide acid to [value missing]. In control group 3, the mass percentage of halo acids was set as follows: The anchoring mass per unit area of ​​mineral salt in control group 4 was set as follows: The anchoring mass per unit area of ​​mineral salts in control group 5 was set as follows: .

[0027] Table 1: Comparison of Performance Data of Subgrade Materials under Different Process Parameters

[0028] According to the data in Table 1, when the mass percentage of halogen acids is at... to Within the specified range, the compressive strength of the material increases positively with increasing acid concentration, indicating that the increase in the depth of the etched micropits provides sufficient deposition space for mineral salts. When the concentration is below a certain range... When the surface etching of the particles is insufficient, the osmotic pressure dynamics weaken, and the whisker aspect ratio decreases. When the concentration exceeds [a certain value], [further action occurs]. Excessive chemical erosion damaged the strength of the fly ash particle skeleton, causing the compressive strength growth trend to inflection point and decline. Control group 1 showed a significant decrease in compressive strength and an increase in penetration depth, demonstrating the role of high-frequency vibration energy as a dynamic compensation mechanism in driving the penetration of liquid-phase excited components into the etched region; regarding the osmotic pressure difference... The verification process is as follows: three mineral salt enrichment gradients are set and the formula is applied. The theoretical osmotic pressure difference within the micro-region was calculated, where, This represents the osmotic pressure difference, in units of... ; Van der Hoff factor for highly soluble mineral salts; This represents the molar concentration of highly soluble mineral salts within the etched micropits, in units of... ; Let be the ideal gas constant, and take the value of . ; The thermodynamic temperature of the curing environment, in units of Experiments have shown that as the mineral salt enrichment quality decreases... Upgraded to The generated calcium silicate gel whiskers increase in density within the pores, forming a three-dimensional network anchoring structure. When the anchoring quality reaches... At that time, due to the explosive nucleation caused by the high concentration of solute, the hydration products rapidly accumulated at the opening of the etched micro-pits, resulting in a blocking effect and limiting the directional transport of later products to the deep pores. The overall mechanical strength and chloride ion penetration resistance of the roadbed material depend on the directional crystallization growth mode driven by the osmotic pressure difference. By establishing a physical link from the inside of the particles to the external pores, the hydration products form a mechanical anchor between the fly ash particles and the crushed stone aggregate. This preparation method utilizes the harmful ion concentration gradient to drive the self-densification of the structure in the marine environment, so that the roadbed material has stable durability indicators.

[0029] Example 3: This example combines Figures 1 to 2 The preparation method of high-performance roadbed materials based on fly ash modification is described, such as... Figure 1As shown, in step S101, an atomized activator containing halogen acid and mineral salt solute is sprayed onto the surface of fly ash particles. The halogen acid is used to etch micron-sized pits and deposit mineral salts in situ, forming a mineral salt enrichment layer with a concentration gradient. In step S102, the surface-activated fly ash particles, aggregates, alkaline activators, and mixing water are mixed and stirred according to a preset ratio to obtain a roadbed mixture. In step S103, the roadbed mixture is spread on the working surface. During the compaction operation, high-frequency vibration energy is applied to reduce wetting resistance and force the liquid-phase alkaline activating components into the etched micro-pits. Finally, in step S104, the fly ash particles undergo a hydration reaction. The osmotic pressure difference generated by the dissolution of the mineral salt enrichment layer is used as a power source to drive the hydration products to grow directionally from the inside of the pits to the outside, forming an interface with a mechanical anchoring structure between the fly ash particles and aggregates.

[0030] like Figure 2 As shown, the reaction system comprises six key elements: an alkaline activator, fly ash particles, a mineral salt enrichment layer, hydration products, a polarity regulating component, and aggregate porosity. The interaction process begins in the hydration reaction initiation stage, where the alkaline activator triggers an alkaline activation reaction and a pozzolanic reaction in the fly ash particles, generating calcium silicate gel. In the osmotic pressure-driven stage, the mineral salt enrichment layer undergoes mineral salt dissolution, generating a high osmotic pressure differential, providing directional growth momentum when the osmotic pressure exceeds the external erosion pressure. Subsequently, in the potential regulation stage, as the system's pH increases and potential reversal occurs, the polarity regulating component repels the products from accumulating at the pithead and guides them towards the external pores. Finally, in the anchoring structure formation stage, the hydration product whiskers penetrate the aggregate micropores, forming a high aspect ratio whisker structure with an aspect ratio greater than 30, thereby establishing a mechanical anchoring interface.

[0031] Example 4: In addressing the fluctuation in subgrade material strength due to variations in fly ash sources, a procedure for determining parameters related to the density of surface active sites was implemented. The initial specific surface area of ​​the fly ash to be treated was obtained using a specific surface area analyzer. The unit is The anchoring mass per unit area of ​​the target mineral salt is selected as follows: The total mass of mineral salts in the atomizing activator is determined using the following formula. : ,in, The total mass of mineral salt solutes is expressed in units of 1000 liters. ; The anchoring mass per unit area of ​​the target mineral salt, in units of ; The initial specific surface area of ​​fly ash, in units of ; The total mass of fly ash added to the reaction, in units of... To ensure uniform deposition of highly soluble mineral salts within the etched micro-pits, an online conductivity meter was used to monitor the charge density of the sprayed droplets, and the atomization voltage was controlled to maintain a suitable droplet charge-to-mass ratio. to Within a certain range, droplets occupy defect sites on the fly ash surface under electrostatic adsorption, reaching an etching depth of [missing information]. At m, the thickness of the residual liquid film on the surface was measured using an infrared moisture analyzer. When the thickness decreased to m to At the critical point m, moisture evaporation compensation is stopped, inducing solute to precipitate at the bottom of the pit, forming a mineral salt enrichment layer with a concentration gradient. The potential reversal point calibration procedure for the polarity-adjusting components is executed, and the cationic polymer containing quaternary ammonium groups is formulated to a mass percentage of [missing information]. A standard solution was used, and the potentiometric analysis was employed to record the solution at different temperatures. In the environment Potential value, when the system Value by Rise to At that time, due to the deprotonation of the side groups of the molecular chain, the surface of the cationic polymer... Potential from decay to The potential reversal point is calibrated at Value The node is when the hydration reaction enters the acceleration phase and the system Value exceeds At this time, the reversed negative potential generates an electrotropic repulsive force, inhibiting the adsorption of negatively charged hydrated calcium silicate precursor at the opening of the etched micro-pits, thus causing the reaction products to conform to the osmotic pressure. The pressure gradient extends away from the aggregate pores, resulting in an average aspect ratio greater than [value missing]. Calcium silicate gel whiskers.

[0032] An adjustment method based on the cumulative shear work value is introduced into the mixing process, and the mixing resistance torque is collected in real time by a torque sensor installed on the main shaft of the mixer. The total shear work during the mixing process is calculated using integration. ,in, Total shearing work, in units of ; Angular velocity, unit: ; The drag torque varies with time, with units of ,when Reaching the threshold At that time, the coverage of the alkaline activator in the non-etched area of ​​the fly ash surface is not less than At this point, the vibration frequency applied by the compaction procedure is... And the amplitude is The mechanical energy, under this energy input, reduces the molar concentration of dissolved mineral salts inside the etched micro-pits. for Substitute into the osmotic pressure formula Generate instantaneous driving pressure This pressure is greater than the hydrostatic osmotic pressure of the external environment, establishing a physical dynamic channel for the unidirectional output of hydration products. By quantitatively mapping the surface area of ​​raw materials to the mass of solute and calibrating the potential reversal threshold, the growth path of hydration products can be controlled. When using fly ash samples from different sources, the atomization activator ratio is adjusted according to the above procedure to prepare the roadbed material. The deviation rate of compressive strength is determined by Reduce to Within this range, and the average aspect ratio of the generated calcium silicate gel whiskers remains within a certain range. above.

[0033] Example 5: In the case of fluctuations in the strength of roadbed materials caused by fly ash from different sources, a spray intensity calibration method was implemented, and the following values ​​were taken: The fly ash sample was dispersed in In deionized water, Record the adjustment system using an automatic titrator under the specified conditions. Value to The required volume of standard halide acid solution ,in, This is the volume of a standard halide acid solution, in units of... This was used to determine the acid-base buffering capacity benchmark of fly ash surface, utilizing The measured value was used to adjust the spray volume of the atomizing activator, thereby controlling the etching depth within... m, the dissolution rate of aluminum and silicon ions in the etching solution film was monitored using inductively coupled plasma atomic emission spectrometry (ICP-AES). When the dissolution rate was within a certain range... to Within a certain range, the surface activation energy level is determined to meet the kinetic requirements for the directional growth of hydration products.

[0034] To address the impact of ionic strength in on-site mixing water on the sensitivity of polarity-regulating components, an electrochemical parameter compensation method was employed, and the initial conductivity of the on-site mixing water samples was measured. ,in, Initial conductivity, in units of Based on this, the amount of highly soluble mineral salt to be added was determined to offset the deviation caused by fluctuations in ionic strength. A cationic polymer containing quaternary ammonium groups was added to a simulated pore liquid with the target ionic strength to adjust... Value by Upgraded to The characteristic curves of the surface potential of the polarity-modifying component as a function of pH were recorded using a microelectrophoresis apparatus. Potential at Value When the potential changes from positive to negative, the potential changes from positive to negative. The electromotive force of the polarity-adjusting component is expressed in units of . The electrostatic repulsion after flipping drives the generated calcium silicate gel whiskers to avoid the physical constraints at the openings of the etched micro-pits and extend towards the center of the pores. Parameter adjustments based on the site environment and material properties ensure that the interface anchorage strength of different construction sections remains constant. to Within the range.

[0035] Example 6: In the construction of thick-layer marine roadbeds, the mechanical vibration energy decreases with increasing depth, and the density of the mixture in the bottom layer is lower than the design expectation. Threshold, perform hydrophobic coating dissolution time delay calibration, select median particle size as The lightly calcined magnesium oxide micro powder of m is used in the coating process by utilizing the mass fraction of the coating agent. With hydration trigger time The mapping logic between them determines the process parameters, according to the formula. The required delay start time for different paving depths was calculated, where, Hydration trigger time, in units of , The hydrophobic time delay coefficient is taken as a value of , This represents the mass fraction of the coating agent, in units of... The calibrated expansion components were divided into mass fractions. Add to the subgrade mixture, at a paving thickness of And the compaction work is completed Subsequently, the underlying coating layer failed due to erosion in the alkaline environment. The micro-expansion force generated by the lightly burned magnesium oxide compensated for the energy loss during mechanical compaction, resulting in a density deviation on the vertical profile of the roadbed. Within.

[0036] When processing fly ash particles with different morphological characteristics, the space utilization rate of etched micro-pits was calculated. The activated fly ash particle samples were observed and recorded using a scanning electron microscope. Pock depth values ​​at random sites Calculate the average etching depth ,when In m to When the value is within the range of m, according to the formula Adjusting the mineral salt solute concentration of the atomizing activator ,in, This represents the concentration of mineral salt solutes in the atomizing activator, in units of... , The anchoring mass per unit area of ​​mineral salt, in units of , Average etching depth, in units of m, The pit filling ratio coefficient is used as the basis for determining the specific process. Under this procedure, the flow rate of the spray system is adjusted in real time to allow different batches of fly ash particles to form a mineral salt enrichment layer with directional penetration driving force within the etched micro-pits. The aspect ratio of the generated hydration product whiskers is maintained at a certain level. The above, and form a mechanical anchoring layer within the roadbed structure.

[0037] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing high-performance roadbed materials based on fly ash modification, characterized in that, Includes the following steps: Step S101: Spray an atomizing activator onto the surface of fly ash particles to perform surface activation treatment. The atomizing activator includes 0.5% to 1.2% by mass of halogen acid and a solute composed of highly soluble mineral salts. The halogen acid is used to etch the surface of the fly ash particles to form micron-level etched pits, and the highly soluble mineral salts are deposited in situ within the etched pits to construct a mineral salt enrichment layer with a concentration gradient. Step S102: The surface-activated fly ash particles, aggregates, alkaline activator and mixing water are mixed and stirred according to a preset ratio to obtain the roadbed mixture. Step S103: Spread the roadbed mixture on the roadbed working surface. During the compaction operation, apply high-frequency vibration energy to the roadbed mixture using a vibratory roller. Use high-frequency vibration energy to reduce the wetting resistance of the fly ash particles and press the liquid phase alkaline activation component in the roadbed mixture into the etched micro-pits. In step S104, the fly ash particles undergo a hydration reaction under the action of an alkaline activator. The osmotic pressure difference generated after the mineral salt enrichment layer dissolves serves as a power source, driving the generated hydration products to crystallize and grow directionally from the inside of the etched micro-pits to the external interconnected pores, forming an interface with a mechanical anchoring structure between the fly ash particles and the aggregate.

2. The method for preparing high-performance roadbed material based on fly ash modification according to claim 1, characterized in that, The process conditions for surface activation treatment in step S101 are as follows: the atomized droplet size of the atomized activator is controlled to be 10 μm to 50 μm, and the mass ratio of the atomized activator to fly ash particles is controlled to be 0.02 to 0.

05. Localized differential etching is generated by the discontinuous liquid film formed by the atomized droplets on the surface of the fly ash particles.

3. The method for preparing high-performance roadbed material based on fly ash modification according to claim 1, characterized in that, In step S101, the average depth of the etched micro-pits is 0.5 μm to 2.5 μm, and the anchoring mass of the mineral salt per unit area in the mineral salt enrichment layer is 15 g / m². 2 Up to 40g / m 2 .

4. The method for preparing high-performance roadbed material based on fly ash modification according to claim 1, characterized in that, The operating parameters for applying high-frequency vibration energy in step S103 are: controlling the vibration frequency to be 25Hz to 50Hz, controlling the amplitude to be 0.6mm to 1.5mm, and controlling the number of compaction passes to be 4 to 8.

5. The method for preparing high-performance roadbed material based on fly ash modification according to claim 1, characterized in that, The quantitative characterization formula for the osmotic pressure difference in step S104 is as follows: ,in, This is the calculated value of the osmotic pressure difference, in MPa; Van der Hoff factor for highly soluble mineral salts; This refers to the molar concentration of highly soluble mineral salts within the etched micro-pits. It is the ideal gas constant; The thermodynamic temperature for maintaining the environment; by setting the initial addition amount of highly soluble mineral salts, the calculated... The value is not less than 1.5 times the osmotic pressure of the preset external salt water erosion environment.

6. The method for preparing high-performance roadbed material based on fly ash modification according to claim 1, characterized in that, In step S102, the alkaline activator is selected from at least one of sodium hydroxide, sodium silicate, and sodium aluminate. The added mass of the alkaline activator is 4% to 8% of the mass of fly ash particles, and the water-cement ratio in the roadbed mixture is 0.28 to 0.

35.

7. The method for preparing high-performance roadbed material based on fly ash modification according to claim 1, characterized in that, The following mixing process is adopted in step S102: the aggregate and the surface-activated fly ash particles are dry-mixed for 60s to 90s, the mixture of mixing water and alkaline activator is added, and the mixture is stirred for 120s to 180s at a speed of 40r / min to 60r / min.

8. The method for preparing high-performance roadbed material based on fly ash modification according to claim 1, characterized in that, Step S104 also includes spraying a curing sealant on the paved subgrade surface to seal the pores on the subgrade surface, thereby maintaining the moisture gradient inside the subgrade mixture and guiding the hydration products to form an interwoven structure along the pore channels.

9. The method for preparing high-performance roadbed material based on fly ash modification according to claim 1, characterized in that, The hydration product in the mechanical anchoring structure is calcium silicate gel whiskers with an average aspect ratio of not less than 30. The whiskers are used to form a physical shielding barrier by cross-stabilizing at the opening of the etched micro-pits.

10. The method for preparing high-performance roadbed material based on fly ash modification according to claim 1, characterized in that, In step S102, a polarity regulating component with potential modification function is also introduced. The polarity regulating component is a cationic polymer containing quaternary ammonium salt groups. The polarity regulating component is used to adjust the charge distribution on the surface of fly ash particles during the hydration reaction to enhance the crystallization motive force for the hydration product to extend and grow into external pores.

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