A bio-enzyme solidified road layer paving method based on soil waste material resourceization

Abstract

The application relates to the field of road engineering construction, in particular to a bio-enzyme solidified road layer paving construction method based on soil waste resource utilization; the method comprises the following steps: classifying and diagnosing waste soil and carrying out differentialized and cooperative pretreatment, adopting high-iron potassium oxide passivation high-organic soil, quicklime composite modified expansive soil and active magnesium oxide solid sealing heavy metal contaminated soil; preparing calcium alginate embedding slow-release type bio-enzyme composite solidified agent and compounding nano silicon dioxide and polypropylene fibers; actively adjusting the water temperature for mixing according to the air temperature, combining a microwave moisture sensor to realize closed-loop control of the water content; intelligently paving and self-adaptively selecting rolling tools according to the aggregate content, cooperating with a nuclear density instrument to form a compaction degree closed loop; constructing a composite seal layer and carrying out temperature control and moisture curing; through the cooperation of materials, processes and detection, the method realizes high-value resource utilization of the waste soil, the solidified layer has high strength, good durability and a wide construction window period, and is suitable for the construction of road bases and temporary roads at all levels.

Description

Technical Field

[0001] This invention relates to the field of road construction engineering, and specifically to a bio-enzyme-cured road paving construction method based on the resource utilization of soil waste. Background Technology

[0002] Road construction requires a large amount of sand and gravel materials, and the extraction of materials from mountains severely damages the ecological environment. Using bio-enzyme soil stabilizers to solidify various soil waste materials (construction slag, expansive soil, high-organic-matter silt, tailings powder, etc.) in situ to construct road base layers is an important direction for green road construction. Bio-enzymes reduce the thickness of the water film on the surface of clay particles through catalysis, making them easier to compact under compaction. Combined with energy agents such as cement, they can form a structural layer with load-bearing capacity and water stability.

[0003] However, the technology faces the following unresolved bottlenecks in its practical application, limiting its use in large-scale, high-grade applications: extremely poor applicability to waste soil; highly random composition of engineering waste materials, with high organic matter content severely inhibiting enzyme activity; dramatic expansion and contraction of expansive soil; heavy metal contaminated soil may cause enzyme protein denaturation; lack of a universal pretreatment and solidification scheme that can simultaneously address various inferior soil materials; lack of guarantee for long-term durability and fatigue performance; weak resistance to reflective cracking, erosion, and freeze-thaw cycles in simple enzyme-cement solidification systems, with severe performance degradation under vehicle cyclic loads and decades of environmental aging, and a lack of reliable reinforcement and toughening methods; a sharp contradiction between maintaining biological enzyme activity and the construction window period; enzyme activity relies on suitable temperature, humidity, and pH after spraying, and if construction is delayed due to high or low temperatures, rainfall, or mechanical failure, enzyme activity will irreversibly decrease, leading to the scrapping of the structural layer; There is a lack of systematic response to the impact of weather and environmental factors; enzyme catalysis stops at low temperatures, and freezing causes structural damage; high temperatures lead to enzyme thermal denaturation and excessively rapid evaporation of moisture; rainfall causes erosion and weak interlayers; existing construction methods lack effective climate-adaptive regulation mechanisms. In view of this, in order to overcome the above-mentioned technical problems, the present invention proposes a bio-enzyme-cured road paving construction method based on the resource utilization of soil waste. Summary of the Invention

[0004] The purpose of this invention is to provide a bio-enzyme-cured road paving construction method based on the resource utilization of soil waste materials, so as to solve the problems of poor universality, insufficient durability, and weather-dependent construction window of waste soil materials, and realize the rapid green construction of road structure layers in all climates and multiple scenarios.

[0005] To achieve this objective, the present invention provides the following technical solution: This invention proposes a bio-enzyme-cured road paving construction method based on the resource utilization of soil waste, comprising the following steps: S1. Waste Material Classification, Diagnosis, and Co-processing: Rapidly sample and test waste soil on-site to obtain organic matter content, mineral composition, heavy metal content, and engineering characteristic indicators; when the organic matter mass ratio is greater than 2.5%, add potassium ferrate solution to the soil for chemical oxidation and passivation; when it is determined to be expansive soil, add a composite modifier composed of quicklime and fine sand with a particle size of less than 0.5 mm, and let it sit for 12-24 hours; when the heavy metal content exceeds the background threshold, add active magnesium oxide for adsorption and solidification; after treatment, test the plasticity index and free expansion rate of the modified soil to ensure that the plasticity index is not greater than 28 and the free expansion rate is less than 45%, thus obtaining the base material; S2. Preparation of encapsulated slow-release bio-enzyme composite curing agent: The bio-enzyme stock solution is mixed with sodium alginate solution as the aqueous phase, and injected into calcium chloride solution under stirring to cross-link and form microcapsules encapsulating the enzyme. Then, it is dry-mixed evenly with nano-silica, polypropylene fiber and silicate cement with a strength grade of not less than 42.5 in a predetermined ratio to obtain the composite curing agent. S3. Initial Dry Mixing and Temperature-Controlled Water Adjustment: The base material obtained in S1 is uniformly dry mixed with the dry composite curing agent in S2; temperature-controlled water adjustment uses only clean water, which is sprayed and mixed to prevent the microcapsules from prematurely contacting the high-alkali slurry and breaking; after rolling and extruding the microcapsule wall material, the bio-enzyme is released slowly; the microwave moisture sensor sampling frequency is ≥10 times / second, and when the moisture content deviation is >±1%, the system automatically starts spraying water / stirring and drying, with a system response time ≤15s; The adjustment logic for the mixing water temperature is as follows: when the ambient temperature at the construction site is higher than 30℃, use cold water at 5℃~10℃; when the ambient temperature at the construction site is lower than 10℃, use warm water at 20℃~25℃; the optimal moisture content is determined through indoor compaction tests. S4. Fine Mixing: Perform at least two high-lift, high-throw mixing operations on the sprayed mixture to ensure uniform dispersion of the microcapsules. After mixing, a solidified mixture is obtained. During the mixing stage, the mass percentage of aggregates with a particle size greater than 2mm in the mixture is tested. When the aggregate percentage is >55%, a block roller is used in the high-vibration compaction stage. When the aggregate percentage is ≤55%, a smooth-drum roller is used, and the corresponding compaction equipment is directly matched after paving. S5. Paving and Intelligent Control: The solidified mixture is transported to the working surface and paved according to the designed loose paving thickness. During the paving process, the paving thickness and surface flatness are detected in real time using a laser level and ultrasonic sensors. The data is fed back to the paver control system to dynamically adjust the screed height and travel speed. The allowable deviation of the loose paving thickness is ±10mm, and the standard deviation of the paving layer flatness is ≤3mm. When the threshold is exceeded, the paver will automatically reduce its travel speed and raise / lower the screed height. S6. Compaction and compaction degree closed loop: Compaction is carried out in the order of initial static rolling, strong vibratory rolling, and final finishing; during the rolling process, a nuclear density meter is used to detect the compaction degree. If the design requirements are not met, the number of rolling passes is increased. If the compaction degree does not meet the standard, first retest the moisture content of the mixture on site: if the moisture content deviation is > ±1%, transport it back to the mixing plant for temperature-controlled water adjustment and secondary fine mixing; if the moisture content is qualified, add 1 to 2 more passes of strong vibration compaction. Operators of nuclear density meters must hold a radioactive equipment operation certificate. Radiation warning signs must be set up in the work area. The equipment must undergo an annual radiation safety inspection. Short-term single-point testing should be used to reduce the duration of radiation exposure. When there are no radiation testing conditions, the sand filling method can be used to test compaction. S7. Composite Sealing and Curing: Immediately after compaction, spray a layer of fast-setting curing film forming agent or cationic emulsified asphalt onto the surface, then evenly spread dry cement, and statically roll to smooth and form a composite sealing layer; the total construction time of the composite sealing layer should be controlled within 30 minutes after compaction; then cover with geotextile, and take heat preservation or water spraying cooling measures according to the ambient temperature, and keep moist for no less than 7 days; The fast-setting curing film forming agent is a composite aqueous solution of water glass and potassium silicate, with a spraying amount of 0.2-0.5 kg / m²; the dry cement spreading amount is 0.3-0.8 kg / m²; when the ambient temperature is below 5℃, an insulation blanket is added to the geotextile and an electric heating blanket is laid for heating curing; the temperature inside the electric heating blanket curing layer is controlled at 8-12℃, and a temperature control power-off protection is set, automatically cutting off the power when the temperature is >15℃ to prevent rapid evaporation of moisture and premature thermal denaturation of biological enzymes.

[0006] The electric blankets used for maintenance are waterproof and insulated, and equipped with leakage protection devices. Metal objects must not be allowed to puncture the insulation layer in the laying area, and the main power supply must be cut off every day when work is stopped.

[0007] Preferably, in S1, the mass concentration of the potassium ferrate solution is 1%–5%, the dosage is 0.5%–2% of the dry soil mass, and the passivation reaction time is 30–60 minutes; the dosage of the active magnesium oxide is 2%–8% of the dry soil mass; wherein, when the organic matter content is 2.5%–4%, the mass concentration of the potassium ferrate solution is 1%–2%, the dry soil dosage is 0.5%–1%, and the passivation time is 30 minutes; when the organic matter content is >4%, the mass concentration of the potassium ferrate solution is 3%–5%, the dry soil dosage is 1%–2%, and the passivation time is 45–60 minutes.

[0008] Preferably, in the composite modifier for expansive soil in S1, the amount of quicklime is 2% to 4% of the dry soil mass, and the amount of fine sand is 15% to 25%, so that the plasticity index of the soil drops below 28 after the material is left to stand.

[0009] Preferably, the preparation parameters of the microcapsules in S2 are as follows: sodium alginate solution mass concentration 2%–4%, calcium chloride solution mass concentration 3%–5%, crosslinking time 15–30 minutes, and the resulting microcapsule particle size range is 50–200 micrometers; the amount of nano-silica is 0.5%–2% of the cement mass, and the amount of polypropylene fiber is 0.1%–0.3% of the total volume of the mixture; wherein, microcapsules with a particle size of 50–100 μm are selected for high-clay soil, and microcapsules with a particle size of 100–200 μm are selected for waste soil containing coarse aggregate.

[0010] Preferably, the temperature control logic for the mixing water in S3 is as follows: when the temperature at the construction site is higher than 30℃, cold water of 5℃~10℃ is used; when the temperature at the construction site is lower than 10℃, warm water of 20℃~25℃ is used; the optimal moisture content is determined by indoor compaction test.

[0011] Preferably, the compaction test frequency in S6 is one cross section every 50m, with no less than 3 measuring points per cross section; for formal roads, the compaction control standard is no less than 96%, and for temporary construction access roads, the compaction control standard is no less than 93%; if the test value does not meet the standard, 1 to 2 more passes of strong vibration compaction are added.

[0012] Preferably, the fast-setting curing film forming agent in S7 is a composite aqueous solution of water glass and potassium silicate, with a spraying amount of 0.2 to 0.5 kg / m²; the dry cement spreading amount is 0.3 to 0.8 kg / m²; when the ambient temperature is below 5°C, an insulation blanket is added to the geotextile and an electric heating blanket is laid for heating and curing.

[0013] Preferably, in S1, the rapid detection uses a portable near-infrared soil organic matter detector to determine the organic matter content, a handheld X-ray fluorescence analyzer to determine the heavy metal content, and a graduated cylinder method to determine the free expansion rate; in S5, the laser leveling instrument and ultrasonic sensor data are combined with real-time dynamic positioning technology to generate a paving layer thickness cloud map for quality traceability.

[0014] The classification and pretreatment in S1 broadens the applicable boundaries of soil materials; the microcapsule and nano-reinforcement in S2 solve the core contradiction of poor durability and easy loss of enzyme activity; the temperature-controlled water regulation in S3 enables construction to actively adapt to high and low temperature environments; the intelligent detection in S5 and S6 forms a multi-dimensional quality closed loop of thickness, flatness, and compaction; and the composite sealing layer and temperature-controlled curing in S7 provide a reliable guarantee for strength development. The entire method achieves climate adaptation and quality control throughout the entire chain from raw materials to curing.

[0015] In this invention, to quantitatively describe and strictly control construction quality, the following key calculation and evaluation formulas are introduced: (1) Moisture content of the mixture Moisture content was monitored in real time during construction. Defined as the percentage of water mass to the total mass of dried solids: In the formula: —Total mass of water in the mixture (g); —The total mass (g) of all dry solid materials (including solid components of soil, cement, sand, lime and other admixtures) in the mixture; this parameter is the core indicator for controlling the activity of biological enzymes and the compaction effect.

[0016] (2) Compaction degree compaction Used to evaluate the compaction effect of rolling operations, it is defined as the ratio of the field-measured dry density to the maximum dry density obtained from the indoor standard compaction test: In the formula: —The dry density of the cured layer (g / cm³) measured on-site using a nuclear density meter or sand filling method. —Maximum dry density (g / cm³) determined by indoor heavy compaction test.

[0017] (3) Unconfined compressive strength Unconfined compressive strength of solidified soil specimens It is a key mechanical parameter for evaluating its load-bearing capacity, calculated using the following formula: Where: F—the maximum vertical load (N) that the specimen can withstand when it fails; A—the initial cross-sectional area of ​​the specimen (mm²).

[0018] Unconfined compressive strength test specimens were standard Φ50mm×50mm cylindrical specimens, with a loading rate of 1mm / min, in accordance with the "Test Procedure for Inorganic Binder Stabilized Materials for Highways" JTG E51-2009.

[0019] (4) Freeze-thaw cycle strength loss rate To evaluate the durability of the cured layer in seasonally frozen areas, the freeze-thaw cycle strength loss rate was introduced. : In the formula: —Initial unconfined compressive strength (MPa) of specimens that have not undergone freeze-thaw cycles; —Unconfined compressive strength (MPa) of the specimen after N freeze-thaw cycles.

[0020] A single freeze-thaw cycle test consists of freezing at -18℃ for 12 hours and thawing at 20℃ for 12 hours. The number of freeze-thaw cycles N can be adjusted according to the road engineering grade and the freezing zone grade of the project location. This evaluation adopts N=5 cycles, and is carried out in accordance with JTG E51.

[0021] (5) Encapsulation rate of biological enzymes The quality of microcapsule preparation is characterized by encapsulation efficiency E, defined as the percentage of enzyme mass successfully encapsulated within the microcapsule relative to the total enzyme mass input. In the formula: —Effective enzyme mass (g) measured after microencapsulation and exfoliation. —The total mass (g) of the biological enzyme stock solution added during preparation, converted to pure enzyme.

[0022] (6) Free expansion rate To evaluate the effect of expansive soil modification, the free swelling rate was used. As a basis for judgment: In the formula: —Initial bulk volume of the dried soil sample (mL); —The volume (mL) of the soil sample after it has fully expanded and stabilized in water.

[0023] The beneficial effects of this invention are as follows: 1. This invention establishes a classification diagnosis and synergistic pretreatment mechanism. For soils with high organic matter, potassium ferrate oxidation and passivation are used to eliminate enzyme activity inhibition. For expansive soils, quicklime-fine sand composite modification is used to inhibit swelling and shrinkage. For soils contaminated with heavy metals, active magnesium oxide is used for solidification and fixation. This enables various types of waste soils that were originally unusable to be used as qualified base materials, significantly broadening the source of raw materials and reducing the amount of waste. 2. This invention protects enzyme activity through microencapsulation and slow-release technology, preventing premature consumption under harsh environments such as high temperatures and rainfall. By actively controlling the temperature of the mixing water, construction can proceed normally under both low-temperature (<5℃) and high-temperature (>35℃) conditions, overcoming the bottleneck of traditional bio-enzyme solidification technology being constrained by weather. Unlike traditional water-soluble slow-release enzymes, the microcapsules of this invention only rupture and release the bio-enzyme under the extrusion of the rolling machinery. The mixing and paving stages are completely isolated from high temperatures, rainwater, and acid / alkali interference, significantly extending the construction window. 3. This invention introduces the volcanic ash filling effect of nano-silica and the random crack-resistant and toughening effect of polypropylene fiber, combined with the composite sealing layer to block moisture migration, which greatly enhances the curing layer's resistance to shrinkage cracks, freeze-thaw cycles, and water erosion. The freeze-thaw strength loss rate can be controlled below 25%, meeting the requirements for long-term use. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the overall process of the construction method of the present invention. Figure 2 This is a schematic diagram of the preparation and microcapsule structure of the slow-release bio-enzyme composite curing agent embedded in S2. Figure 3 Schematic diagram of the intelligent temperature control and water content closed-loop control system in S3; Figure 4 This is the logic diagram for adaptive selection of compaction equipment and closed-loop control of compaction degree in S6. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are merely examples illustrating the technical solution of the present invention and are not intended to limit the scope of protection.

[0026] like Figure 1-4 As shown; Example 1 A bio-enzyme-cured road paving construction method based on soil waste resource utilization includes the following steps: S1. Waste Material Classification, Diagnosis, and Co-processing: Rapidly sample and test waste soil on-site to obtain organic matter content, mineral composition, heavy metal content, and engineering characteristic indicators; when the organic matter mass ratio is greater than 2.5%, add potassium ferrate solution to the soil for chemical oxidation and passivation; when it is determined to be expansive soil, add a composite modifier composed of quicklime and fine sand with a particle size of less than 0.5 mm, and let it sit for 12-24 hours; when the heavy metal content exceeds the background threshold, add active magnesium oxide for adsorption and solidification; after treatment, test the plasticity index and free expansion rate of the modified soil to ensure that the plasticity index is not greater than 28 and the free expansion rate is less than 45%, thus obtaining the base material; The potassium ferrate solution has a mass concentration of 1%–5%, and the dosage is 0.5%–2% of the dry soil mass. The passivation reaction time is 30–60 minutes. The active magnesium oxide dosage is 2%–8% of the dry soil mass. When preparing and mixing the potassium ferrate solution, acid- and alkali-resistant protective gloves and goggles must be worn. Residual waste liquid after passivation must be collected, neutralized, and treated uniformly; it must not be directly discharged into surrounding soil or water bodies.

[0027] The background value thresholds refer to the screening values ​​for Class II land use in the "Soil Environmental Quality Standard for Construction Land Soil Pollution Risk Control (Trial)" GB36600, with a screening value of 1200 mg / kg for Pb and 3500 mg / kg for Zn. If the content of a single heavy metal exceeds the corresponding screening value, it is determined that the heavy metal exceeds the standard. The plasticity index and free expansion rate were tested according to the "Specifications for Testing Geotechnical Engineering for Highways" JTG 3450-2019. The free expansion rate was determined by the graduated cylinder method, and the plasticity index was determined by the combined liquid limit and plastic limit method. After heavy metal contaminated soil is treated with active magnesium oxide for solidification, leaching toxicity testing is carried out in accordance with GB 5086. Only when the heavy metal concentration in the leachate meets the limit of GB 8978 "Integrated Wastewater Discharge Standard" can it be used as roadbed material.

[0028] It should be noted that if the soil material meets multiple deterioration indicators at the same time, the treatment sequence is as follows: the first step is to oxidize and passivate the high organic matter with potassium ferrate (reaction for 30-60 minutes), the second step is to solidify the heavy metals with active magnesium oxide (mix and let stand for 2 hours), and the third step is to modify the expansive soil with quicklime and fine sand, and let it sit for 12-24 hours; the step-by-step treatment avoids the agents reacting with each other and becoming ineffective.

[0029] S2. Preparation of encapsulated slow-release bio-enzyme composite curing agent: The bio-enzyme stock solution is mixed with sodium alginate solution as the aqueous phase, and injected into calcium chloride solution under stirring to cross-link and form microcapsules encapsulating the enzyme. Then, it is dry-mixed evenly with nano-silica, polypropylene fiber and silicate cement with a strength grade of not less than 42.5 in a predetermined ratio to obtain the composite curing agent. The standard mass ratio of the composite curing agent is: 100 parts silicate cement, 8-12 parts calcium alginate microcapsules, 0.5-2 parts nano silica, and 0.1-0.3 parts polypropylene fiber. The preparation parameters for the microcapsules are as follows: sodium alginate solution concentration of 2%–4% by mass, calcium chloride solution concentration of 3%–5% by mass, cross-linking time of 15–30 minutes, and the resulting microcapsule particle size range of 50–200 micrometers; the amount of nano-silica added is 0.5%–2% of the cement mass, and the amount of polypropylene fiber added is 0.1%–0.3% of the total volume of the mixture; S3. Initial Dry Mixing and Temperature-Controlled Water Adjustment: The base material obtained in S1 is uniformly dry-mixed with the dry composite curing agent in S2; temperature-controlled water adjustment uses only clean water, which is sprayed and mixed to prevent the microcapsules from prematurely contacting the high-alkali slurry and breaking; after rolling and extruding the microcapsule wall material, the bio-enzyme is released slowly. The calcium alginate wall material of the microcapsule remains intact when exposed to water, and the release of bio-enzyme is achieved by mechanical extrusion of the rolling machinery, rather than by dissolving and releasing it when exposed to water; and an insertion microwave moisture sensor is used to monitor in real time and control the moisture content of the mixture within ±1% of the optimal moisture content; the microwave moisture sensor sampling frequency is ≥10 times / second, and when the moisture content deviation is >±1%, the system automatically starts spraying water / stirring and drying, with a system response time ≤15s; The adjustment logic for the mixing water temperature is as follows: when the ambient temperature at the construction site is higher than 30℃, use cold water at 5℃~10℃; when the ambient temperature at the construction site is lower than 10℃, use warm water at 20℃~25℃; the optimal moisture content is determined through indoor compaction tests. S4. Fine mixing: Perform at least two high-lift and high-throw mixing operations on the sprayed mixture to ensure uniform dispersion of the microcapsules. After mixing, a solidified mixture is obtained. S5, Paving and Intelligent Control: If the mass percentage of aggregate with a particle size greater than 2mm in the mixture is >55% during the mixing stage, a block roller should be used during the high-vibration compaction stage; if the aggregate is ≤55%, a smooth-drum roller should be used, and the corresponding compaction equipment should be directly matched after paving. The solidified mixture is transported to the working surface and spread according to the designed loose paving thickness. During the paving process, a laser leveling instrument and an ultrasonic sensor are used to detect the paving thickness and surface flatness in real time, and the data is fed back to the paver control system to dynamically adjust the screed height and travel speed. The allowable deviation of the loose paving thickness is ±10mm, and the standard deviation of the paving layer flatness is ≤3mm. When the threshold is exceeded, the paver will automatically reduce its travel speed and raise / lower the screed height. S6. Compaction and compaction degree closed loop: Compaction is carried out in the order of initial static rolling, strong vibratory rolling, and final finishing; during the rolling process, a nuclear density meter is used to detect the compaction degree. If the design requirements are not met, the number of rolling passes is increased. If the compaction degree does not meet the standard, first retest the moisture content of the mixture on site: if the moisture content deviation is > ±1%, transport it back to the mixing plant for temperature-controlled water adjustment and secondary fine mixing; if the moisture content is qualified, add 1 to 2 more passes of strong vibration compaction. Operators of nuclear density meters must hold a radioactive equipment operation certificate. Radiation warning signs must be set up in the work area. The equipment must undergo an annual radiation safety inspection. Short-term single-point testing should be used to reduce the duration of radiation exposure. When there are no radiation testing conditions, the sand filling method can be used to test compaction. S7. Composite Sealing and Curing: Immediately after compaction, spray a layer of fast-setting curing film forming agent or cationic emulsified asphalt onto the surface, then evenly spread dry cement, and statically roll to smooth and form a composite sealing layer; the total construction time of the composite sealing layer should be controlled within 30 minutes after compaction; then cover with geotextile, and take heat preservation or water spraying cooling measures according to the ambient temperature, and keep moist for no less than 7 days; The fast-setting curing film forming agent is a composite aqueous solution of water glass and potassium silicate, with a spraying amount of 0.2-0.5 kg / m²; the dry cement spreading amount is 0.3-0.8 kg / m²; when the ambient temperature is below 5℃, an insulation blanket is added to the geotextile and an electric heating blanket is laid for heating curing; the temperature inside the electric heating blanket curing layer is controlled at 8-12℃, and a temperature control power-off protection is set, automatically cutting off the power when the temperature is >15℃ to prevent rapid evaporation of moisture and premature thermal denaturation of biological enzymes.

[0030] The electric blankets used for maintenance are waterproof and insulated, and equipped with leakage protection devices. Metal objects must not be allowed to puncture the insulation layer in the laying area, and the main power supply must be cut off every day when work is stopped.

[0031] This invention addresses the construction of road subbases using waste soil with high organic matter content in high-temperature summer environments. The soil material on site is black silty clay produced from dredging. According to a portable near-infrared soil organic matter detector, the organic matter content is 5.1%, the free expansion rate is 38%, the liquid limit is 62%, the plasticity index is 29, and it contains a small amount of humus. Therefore, it is determined to be high organic matter soil and is not suitable for direct use.

[0032] S1: Waste material classification diagnosis and co-processing; Prepare a 3% potassium ferrate solution (by mass). The solution, at 1.5% of the dry soil mass, is sprayed into the soil and thoroughly mixed using a rotary tiller. The reaction time is 45 minutes. The oxidation principle of potassium ferrate is: under hydrated conditions... It has extremely strong oxidizing properties, capable of oxidizing and breaking down large organic molecules like humic acids into smaller organic acids, and even... When mixed with water, it effectively disrupts the ability of soil to chelate and adsorb enzyme proteins, eliminating the inhibitory effect on the activity of biological enzymes; after the reaction, the organic matter content is reduced to below 2.0%; the plasticity index of the treated soil is reduced to 24, and the free swelling rate is calculated according to the formula. The test result was 35%, which meets the design requirements, and the base material was obtained; S2: Preparation of an encapsulated, sustained-release bio-enzyme composite curing agent; See Figure 2 The bio-enzyme stock solution was mixed with a 3% sodium alginate solution to form an aqueous phase, which was then added dropwise to a 4% calcium chloride solution. Cross-linking was performed for 20 minutes to generate calcium alginate microcapsules with a particle size of approximately 100 μm. The encapsulation efficiency was measured. The yield reached 91%; after filtering out the microcapsules, they were dry-mixed evenly with nano-silica (1.2% by cement mass), polypropylene fiber (0.2% by volume), and PO 42.5 cement; the microcapsules can protect enzyme molecules from the effects of high temperature and residual organic acids; the nano-silica reacts with cement hydration products in the later stages. A volcanic ash reaction occurs, generating hydrated calcium silicate gel that fills micropores and improves durability; polypropylene fibers act as bridging agents, inhibiting shrinkage cracks. S3, Initial dry mixing and temperature-controlled water adjustment; On the day of construction, the air temperature reached 38℃, and the material temperature reached 41℃, constituting extreme high-temperature weather. A refrigeration unit was used to produce 8℃ cold water. The composite curing agent and base material were first dry-mixed, and then water was added before spraying. During spraying, if... Figure 3 As shown, an insertion-type microwave moisture sensor installed next to the excavator monitors the moisture content of the material pile in real time at a frequency of 10 times per second; the optimal moisture content is determined through compaction tests. The controller is based on the real-time feedback of the moisture content value. The spray flow rate is automatically adjusted to dynamically maintain the moisture content of the mixture within the range of 13.5%±1%; the low-temperature water can absorb the heat of mixing, reduce the system temperature, and delay the thermal denaturation and inactivation of enzymes during the mixing and paving process. S4. Fine mixing; Three high-lift and high-throw mixing processes were performed, with a throw height of 3.5m, to ensure that the microcapsules and fibers were fully and evenly dispersed. S5, paving and intelligent control; During paving, a laser leveling instrument and an ultrasonic sensor are used to measure the thickness in real time, and the screed is dynamically adjusted. The paving is carried out in layers, with each layer being 20cm loose, and the standard deviation of flatness is controlled to 2.8mm. S6, Closed-loop compaction and compaction degree; This soil material contains no coarse aggregate and is rolled entirely with a smooth-drum roller; two passes of initial compaction and three passes of high-intensity vibration are applied. The dry density is measured at three points using a nuclear density meter every 50 meters. And through the formula Calculate compaction degree; maximum dry density The density was 1.78 g / cm³; during the test, the calculated compaction degree at one point was 95.2%, which was lower than the standard of 96% for formal roads. After one additional vibration test, the dry density was increased and the calculated compaction degree reached 97.1%, thus meeting the closed-loop standard. S7, Composite Sealing and Curing; At high temperatures, moisture evaporates extremely quickly; immediately after compaction, spray 0.4 kg / m² of water glass-potassium silicate composite curing film forming agent, which rapidly reacts with the surface cement to form a dense film; then spread 0.5 kg / m² of dry cement and grind it smooth; subsequently cover with geotextile and sprinkle with water, erect a shade net outside, and spray to cool down every 2 hours to keep the surface moist; after 7 days of curing, core samples are taken according to the formula. The unconfined compressive strength was tested. The cross-sectional area A of the specimen was 1963.5 mm² (diameter 50 mm), and the failure load F was 6087 N. Calculations were performed... Deflection value 110 (0.01 mm), permeability coefficient cm / s, with good durability.

[0033] Example 1 addresses the problem in existing technologies that high-organic-matter silt waste soil cannot be directly used for bio-enzyme solidification. Humic substances in high-organic-matter soil severely adsorb and chelate enzyme proteins, leading to irreversible inhibition of bio-enzyme catalytic activity. Traditional methods only allow for the disposal and replacement of such soil. This example utilizes a dual protection mechanism of potassium ferrate chemical oxidation pretreatment and microcapsule encapsulation. First, the strong oxidizing properties of potassium ferrate break down large organic molecules into smaller molecules, eliminating their inhibitory effect on enzymes. Then, the bio-enzyme is encapsulated in calcium alginate microcapsules, physically isolating it from residual organic acids during mixing and paving, and only releasing it slowly after compaction and cement hydration pH increases. Simultaneously, to address the issues of enzyme protein thermal denaturation and rapid moisture evaporation caused by high-temperature construction in summer, low-temperature water mixing and composite sealing layer temperature control curing are employed, enabling normal construction and strength development under extreme high-temperature weather conditions. Silt soil with an organic matter content of 5.1% can be used as a subbase for formal roads after treatment, achieving an unconfined compressive strength of 3.1 MPa after 7 days, with deflection and permeability meeting design requirements. The soil material on site was black silty clay produced from dredging. According to a portable near-infrared soil organic matter detector, the organic matter content was 5.1%, the free expansion rate was 38%, the liquid limit was 62%, the plasticity index was 29, and it contained a small amount of humus. It was judged to be high organic matter soil and not suitable for direct use.

[0034] Example 2 A bio-enzyme-cured road paving construction method based on soil waste resource utilization includes the following steps: S1. Waste Material Classification, Diagnosis, and Collaborative Pretreatment: Rapidly sample and test waste soil materials on site to obtain organic matter content, mineral composition, heavy metal content, and engineering characteristic indicators; when the organic matter mass ratio is greater than 2.5%, add potassium ferrate solution to the soil for chemical oxidation and passivation; when it is determined to be expansive soil, add a composite modifier composed of quicklime and fine sand with a particle size of less than 0.5 mm, and let it sit for 12-24 hours; when the heavy metal content is detected to exceed the background threshold, add active magnesium oxide for adsorption and solidification; after treatment, test the plasticity index and free expansion rate of the modified soil to ensure that the plasticity index is not greater than 28 and the free expansion rate is less than 45%, thus obtaining the base material.

[0035] In composite modifiers for expansive soils, the amount of quicklime is 2% to 4% of the dry soil mass, and the amount of fine sand is 15% to 25%. After curing, the plasticity index of the soil drops below 28.

[0036] S2. Preparation of encapsulated slow-release bio-enzyme composite curing agent: The bio-enzyme stock solution is mixed with sodium alginate solution as the aqueous phase, and injected into calcium chloride solution under stirring to crosslink and form microcapsules encapsulating the enzyme. Then, it is dry-mixed evenly with nano-silica, polypropylene fiber and silicate cement with a strength grade of not less than 42.5 in a predetermined ratio to obtain the composite curing agent.

[0037] The preparation parameters for the microcapsules are as follows: sodium alginate solution mass concentration 2%–4%, calcium chloride solution mass concentration 3%–5%, cross-linking time 15–30 minutes, and the resulting microcapsule particle size range is 50–200 micrometers; the amount of nano-silica added is 0.5%–2% of the cement mass, and the amount of polypropylene fiber added is 0.1%–0.3% of the total volume of the mixture.

[0038] S3. Initial Dry Mixing and Temperature-Controlled Water Adjustment: The base material obtained in S1 is uniformly dry mixed with the dry composite curing agent in S2; temperature-controlled water adjustment uses only clean water, which is sprayed and mixed to prevent the microcapsules from prematurely contacting the high-alkali slurry and breaking; the microcapsule wall material is rolled and squeezed to release the bio-enzyme; and an insertion microwave moisture sensor is used to monitor in real time and control the moisture content of the mixture within ±1% of the optimal moisture content; the microwave moisture sensor sampling frequency is ≥10 times / second, and when the moisture content deviation is >±1%, the system automatically starts spraying water / stirring and drying, with a system response time ≤15s.

[0039] The adjustment logic for the mixing water temperature is as follows: when the ambient temperature at the construction site is higher than 30℃, use cold water at 5℃~10℃; when the ambient temperature at the construction site is lower than 10℃, use warm water at 20℃~25℃; the optimal moisture content is determined by indoor compaction test.

[0040] S4. Fine mixing: Perform at least two high-lift, high-throw mixing operations on the sprayed mixture to ensure uniform dispersion of the microcapsules. After mixing, a solidified mixture is obtained. During the mixing stage, the mass percentage of aggregates with a particle size greater than 2mm in the mixture is tested. When the aggregate percentage is >55%, a bump roller is used in the high-vibration compaction stage. When the aggregate percentage is ≤55%, a smooth-drum roller is used, and the corresponding compaction equipment is directly matched after paving.

[0041] S5. Paving and Intelligent Control: The solidified mixture is transported to the working surface and paved according to the designed loose paving thickness. During the paving process, the paving thickness and surface flatness are detected in real time using a laser level and ultrasonic sensors. The data is fed back to the paver control system to dynamically adjust the screed height and travel speed. The allowable deviation of the loose paving thickness is ±10mm, and the standard deviation of the paving layer flatness is ≤3mm. When the threshold is exceeded, the paver will automatically reduce its travel speed and raise / lower the screed height.

[0042] S6. Compaction and compaction degree closed loop: Compaction is carried out in the order of initial static rolling, strong vibratory rolling, and final finishing; during the rolling process, a nuclear density meter is used to detect the compaction degree. If the design requirements are not met, the number of rolling passes is increased. If the compaction degree does not meet the standard, first retest the moisture content of the mixture on site: if the moisture content deviation is > ±1%, transport it back to the mixing plant for temperature-controlled water adjustment and secondary fine mixing; if the moisture content is qualified, add 1 to 2 passes of strong vibration compaction; after the treatment is qualified, transport it back to the working surface for paving and restart the paving and compaction process.

[0043] Operators of nuclear density meters must hold a radioactive equipment operation certificate. Radiation warning signs must be set up in the work area. The equipment must undergo an annual radiation safety inspection. Short-term single-point testing should be used to reduce the duration of radiation exposure. When there are no radiation testing conditions, the sand filling method can be used to test compaction.

[0044] S7. Composite Sealing and Curing: Immediately after compaction, spray a layer of fast-setting curing film forming agent or cationic emulsified asphalt onto the surface, then evenly spread dry cement, and statically roll to smooth and form a composite sealing layer; the total construction time of the composite sealing layer should be controlled within 30 minutes after compaction; then cover with geotextile, and take heat preservation or water spraying cooling measures according to the ambient temperature, and keep moist for no less than 7 days.

[0045] Example 2 focuses on the construction of a roadbed improvement layer using expansive soil waste material under low winter temperatures. The soil sample is grayish-white expansive soil with a free expansion rate of 72%, a liquid limit of 70%, and a plasticity index of 38.

[0046] S1. Waste material classification diagnosis and collaborative pretreatment; Add 3% quicklime (by dry weight of soil) and 20% fine sand from mineral processing tailings with a particle size less than 0.5mm, mix thoroughly, and let stand for 20 hours; Working principle: CaO scavenging generates... Provide a large number of The montmorillonite interlayer was replaced by ion exchange. , This process significantly compresses the double electric layer thickness, causing soil particles to shift from dispersion to flocculation, reducing hydrophilicity and plasticity; fine sand particles form a micro-skeleton within the soil, restricting expansion and contraction space. The free expansion rate was determined using the graduated cylinder method after the material was left to stand. Calculated =38%, plasticity index decreased to 24, modification qualified; S2. Preparation of an encapsulated, sustained-release bio-enzyme composite curing agent; The microcapsule preparation was the same as in Example 1, with an encapsulation efficiency E of 90%; the fiber content was increased to 0.25% to resist low-temperature shrinkage and stress generated by freeze-thaw cycles. S3, Initial dry mixing and temperature-controlled water adjustment; During construction, the air temperature was 3℃ and the material temperature was 2℃. The severe cold would cause enzyme catalysis to stop. The heating device was activated to heat the mixing water to 23℃ to prepare a warm suspension for spraying. The microwave moisture sensor monitored the moisture content w in real time and controlled it to be around the optimal value of 15.2%. The heat of the warm water was transferred to the soil-cement mixture, raising the initial temperature of the system to about 12℃, activating the initial activity of the biological enzymes, and promoting the initiation of cement hydration. S4. Fine mixing; The high-lift and high-throw mixing method utilizes the falling process to further mix in gentle air and slow down heat loss; S5, paving and intelligent control; Rapid paving reduces heat loss; thickness and flatness sensor data are combined with RTK to generate cloud maps. S6, Closed-loop compaction and compaction degree; Compaction should follow paving closely; the compaction degree should meet the temporary access road standard of ≥93%, and the measured dry density calculated as K=94.6%, which meets the requirements; S7, Composite Sealing and Curing; Immediately after compaction, a curing film forming agent is sprayed and a cement sealant layer is applied; then, geotextile and a 5cm thick insulation blanket are laid, and the electric blankets laid underneath are turned on to maintain the temperature inside the blanket at 8-12℃ for 7 days of moist curing; after curing, 5 freeze-thaw cycle tests are conducted, using the formula... Calculate the strength loss rate, initial strength Strength after freeze-thaw The loss rate was only 22%, while the loss rate of the control group of ordinary bio-enzyme-stabilized soil was over 60%, which verifies the synergistic improvement in frost resistance by composite modification, microcapsule slow release and temperature-controlled curing.

[0047] Example 2 addresses the dual challenges of expansive soil waste material exhibiting severe swelling and shrinkage upon contact with water, extremely poor durability after bio-enzyme solidification, and structural failure due to enzyme catalysis stagnation and freeze-thaw damage in low-temperature winter environments. Expansive soil is rich in hydrophilic minerals such as montmorillonite, and traditional single-enzyme solidification cannot effectively suppress its drastic volume changes under wet-dry cycles. At the same time, when the construction temperature is below 10°C, the enzyme catalysis reaction almost stops. If it freezes, the frost heave force generated by the freezing of water in the soil will tear apart the cemented structure that has not yet formed strength, and it will completely loosen after thawing.

[0048] Example 2 utilizes a combined approach of quicklime-fine sand composite modification, microcapsule temperature-controlled activation, and low-temperature insulation curing to improve the properties of quicklime. The replacement of montmorillonite interlayer cations compresses the double electric layer and reduces water sensitivity; fine sand forms a rigid framework to inhibit macroscopic expansion and contraction; microcapsules protect enzyme activity from being consumed during the low-temperature mixing stage, and heating with warm water activates the initial catalytic reaction; thermal insulation blankets and electric blankets provide continuous heating to ensure normal growth in the intensity of hydration and enzymatic reactions; technical results: the free expansion rate is reduced from 72% to 38%, and the strength loss rate after 5 freeze-thaw cycles is only 22%, which is far better than the loss rate of more than 60% of ordinary bio-enzyme-stabilized soil, successfully realizing the resource utilization of expansive soil in low-temperature freezing areas in winter; The soil sample was grayish-white expansive soil with a free swelling rate of 72%, a liquid limit of 70%, and a plasticity index of 38.

[0049] Example 3 A bio-enzyme-cured road paving construction method based on soil waste resource utilization includes the following steps: S1. Waste Material Classification, Diagnosis, and Co-processing: Rapidly sample and test waste soil on-site to obtain organic matter content, mineral composition, heavy metal content, and engineering characteristic indicators; when the organic matter mass ratio is greater than 2.5%, add potassium ferrate solution to the soil for chemical oxidation and passivation; when it is determined to be expansive soil, add a composite modifier composed of quicklime and fine sand with a particle size of less than 0.5 mm, and let it sit for 12-24 hours; when the heavy metal content exceeds the background threshold, add active magnesium oxide for adsorption and solidification; after treatment, test the plasticity index and free expansion rate of the modified soil to ensure that the plasticity index is not greater than 28 and the free expansion rate is less than 45%, thus obtaining the base material; The potassium ferrate solution has a mass concentration of 1%–5%, and the dosage is 0.5%–2% of the dry soil mass; the passivation reaction time is 30–60 minutes; the active magnesium oxide dosage is 2%–8% of the dry soil mass. Rapid testing methods included: organic matter content was determined using a portable near-infrared soil organic matter detector, heavy metal content was determined using a handheld X-ray fluorescence analyzer, and free swelling rate was determined using the graduated cylinder method. S2. Preparation of encapsulated slow-release bio-enzyme composite curing agent: The bio-enzyme stock solution is mixed with sodium alginate solution as the aqueous phase, and injected into calcium chloride solution under stirring to cross-link and form microcapsules encapsulating the enzyme. Then, it is dry-mixed evenly with nano-silica, polypropylene fiber and silicate cement with a strength grade of not less than 42.5 in a predetermined ratio to obtain the composite curing agent. S3. Initial Dry Mixing and Temperature-Controlled Water Adjustment: The base material obtained in S1 is uniformly dry mixed with the dry composite curing agent in S2; temperature-controlled water adjustment uses only clean water, which is sprayed and mixed to prevent the microcapsules from prematurely contacting the high-alkali slurry and breaking; the microcapsule wall material is rolled and squeezed to release the bio-enzyme; and an insertion microwave moisture sensor is used to monitor in real time and control the moisture content of the mixture within ±1% of the optimal moisture content; the microwave moisture sensor sampling frequency is ≥10 times / second, and when the moisture content deviation is >±1%, the system automatically starts spraying water / stirring and drying, with a system response time ≤15s; The adjustment logic for the mixing water temperature is as follows: when the ambient temperature at the construction site is higher than 30℃, use cold water at 5℃~10℃; when the ambient temperature at the construction site is lower than 10℃, use warm water at 20℃~25℃; the optimal moisture content is determined through indoor compaction tests. S4. Fine mixing: Perform at least two high-lift and high-throw mixing operations on the sprayed mixture to ensure uniform dispersion of the microcapsules. After mixing, a solidified mixture is obtained. S5. Paving and Intelligent Control: When the mass ratio of aggregate with a particle size greater than 2mm in the mixture is >55% during the mixing stage, a bump roller is used during the high-vibration compaction stage; when the aggregate is ≤55%, a smooth-drum roller is used, and the corresponding compaction equipment is directly matched after paving. The solidified mixture is transported to the working surface and spread according to the designed loose paving thickness. During the paving process, laser leveling instruments and ultrasonic sensors are used to detect the paving thickness and surface flatness in real time. The data is fed back to the paver control system to dynamically adjust the screed height and travel speed. The data from the laser leveling instruments and ultrasonic sensors are combined with real-time dynamic positioning technology to generate a paving layer thickness cloud map for quality traceability. The allowable deviation of the loose paving thickness is ±10mm, and the standard deviation of the paving layer flatness is ≤3mm. When the threshold is exceeded, the paver will automatically reduce its travel speed and raise / lower the screed height. S6. Compaction and compaction degree closed loop: Compaction is carried out in the order of initial static rolling, strong vibratory rolling, and final finishing; during the rolling process, a nuclear density meter is used to detect the compaction degree. If the design requirements are not met, the number of rolling passes is increased. The compaction degree test frequency is one cross section every 50m, with no less than 3 measuring points per cross section; for formal roads, the compaction degree control standard is no less than 96%, and for temporary construction access roads, the compaction degree control standard is no less than 93%; if the test value does not meet the standard, 1 to 2 more passes of strong vibration compaction are added. If the compaction degree does not meet the standard, first retest the moisture content of the mixture on site: if the moisture content deviation is > ±1%, transport it back to the mixing plant for temperature-controlled water adjustment and secondary fine mixing; if the moisture content is qualified, add 1 to 2 more passes of strong vibration compaction. Operators of nuclear density meters must hold a radioactive equipment operation certificate. Radiation warning signs must be set up in the work area. The equipment must undergo an annual radiation safety inspection. Short-term single-point testing should be used to reduce the duration of radiation exposure. When there are no radiation testing conditions, the sand filling method can be used to test compaction. S7. Composite Sealing and Curing: Immediately after compaction, spray a layer of fast-setting curing film forming agent or cationic emulsified asphalt onto the surface, then evenly spread dry cement, and statically roll to smooth and form a composite sealing layer; the total construction time of the composite sealing layer should be controlled within 30 minutes after compaction; then cover with geotextile, and take heat preservation or water spraying cooling measures according to the ambient temperature, and keep moist for no less than 7 days.

[0050] Example 3: Tailings sand waste containing lead and zinc heavy metals was used for the subbase of formal roads; the soil waste was lead-zinc mine tailings with a fineness modulus of 1.8, containing a small amount of clay, with a Pb content of 1200 mg / kg and a Zn content of 890 mg / kg, exceeding environmental standards. S1. Waste material classification diagnosis and collaborative pretreatment; Handheld XRF was used for rapid screening of heavy metal types and contents; activated magnesium oxide was selected for stabilization treatment at a dosage of 5%; activated magnesium oxide reacted with water to produce It has a large specific surface area and high activity, and can stably lock heavy metal ions in the crystal lattice through surface complexation, interlayer precipitation and formation of hydrotalcite-like structures; the leaching toxicity after treatment meets the standards. S2. Preparation of encapsulated sustained-release bio-enzyme composite curing agent; The cement content in the curing agent is increased to 10%, and the nano silica content is 2%. Its pozzolanic activity is used to further fill the micropores between the heavy metal solidification products and reduce permeability. S3. Initial dry mixing, temperature-controlled water adjustment, and subsequent mixing and paving shall be carried out in accordance with conventional procedures; S5, paving and intelligent control; The laser leveling instrument and ultrasonic sensor data are bound to RTK geographic coordinates in real time to generate a full-width thickness point cloud map; during construction, it was found that the thickness of the 3-meter strip on the left side was generally 1.5cm thinner than expected, and the paver was immediately instructed to reduce its travel speed and increase the material supply in that area to achieve dynamic correction; this digital record also serves as the basis for quality acceptance. S6, Closed-loop compaction and compaction degree; The mixture contains 35% particles larger than 2mm, and a smooth-drum roller is used. The standard for compaction control of formal roads is ≥96%. The compaction degree K is detected and calculated by a nuclear density meter. For sections with large dispersion, an additional strong vibration is added to ensure overall uniformity. The final representative value is 97.3%. After curing, the road's resilience modulus reaches 1200MPa, and the leaching concentration of heavy metal solidified body is far below the limit.

[0051] This embodiment addresses the problem in existing technologies where waste soil contaminated with heavy metals cannot be safely recycled for road construction. Tailings sand and other waste materials contain excessive levels of heavy metal ions such as lead and zinc. Traditional bio-enzyme solidification methods lack a stabilization and sealing mechanism for these heavy metals, leading to environmental risks of heavy metal leaching and pollution of surrounding soil and water bodies under long-term rainwater infiltration. This embodiment employs a dual stabilization scheme of chemical sealing with activated magnesium oxide and dense filling with nano-silica. The activated magnesium oxide, after hydration, forms a high specific surface area. Through surface complexation and interlayer precipitation of hydrotalcite-like substances, heavy metal ions are stably locked inside the crystal lattice; nano-silica generates hydrated calcium silicate gel through volcanic ash reaction, which further fills the micropores of the solidified body, reduces the permeability coefficient, and blocks the channels for water infiltration and ion leaching from a physical level; the leaching concentrations of Pb and Zn meet environmental protection standards, the resilience modulus of the solidified body reaches 1200MPa, and the permeability coefficient is extremely low, realizing the safe and high-value utilization of heavy metal contaminated soil in the subbase of formal roads. The waste material in the soil is lead-zinc mine tailings with a fineness modulus of 1.8, containing a small amount of clay particles, a Pb content of 1200 mg / kg, and a Zn content of 890 mg / kg, exceeding environmental standards.

[0052] Example 4 A bio-enzyme-cured road paving construction method based on soil waste resource utilization includes the following steps: S1. Waste Material Classification, Diagnosis, and Co-processing: Rapidly sample and test waste soil on-site to obtain organic matter content, mineral composition, heavy metal content, and engineering characteristic indicators; when the organic matter mass ratio is greater than 2.5%, add potassium ferrate solution to the soil for chemical oxidation and passivation; when it is determined to be expansive soil, add a composite modifier composed of quicklime and fine sand with a particle size of less than 0.5 mm, and let it sit for 12-24 hours; when the heavy metal content exceeds the background threshold, add active magnesium oxide for adsorption and solidification; after treatment, test the plasticity index and free expansion rate of the modified soil to ensure that the plasticity index is not greater than 28 and the free expansion rate is less than 45%, thus obtaining the base material; S2. Preparation of encapsulated slow-release bio-enzyme composite curing agent: The bio-enzyme stock solution is mixed with sodium alginate solution as the aqueous phase, and injected into calcium chloride solution under stirring to cross-link and form microcapsules encapsulating the enzyme. Then, it is dry-mixed evenly with nano-silica, polypropylene fiber and silicate cement with a strength grade of not less than 42.5 in a predetermined ratio to obtain the composite curing agent. The sodium alginate solution had a mass concentration of 2%–4%, the calcium chloride solution had a mass concentration of 3%–5%, and the cross-linking time was 15–30 minutes, resulting in microcapsules with a particle size range of 50–200 micrometers; the nano-silica content was 0.5%–2% of the cement mass, and the polypropylene fiber content was 0.1%–0.3% of the total volume of the mixture. S3. Initial Dry Mixing and Temperature-Controlled Water Adjustment: The base material obtained in S1 is uniformly dry mixed with the dry composite curing agent in S2; temperature-controlled water adjustment uses only clean water, which is sprayed and mixed to prevent the microcapsules from prematurely contacting the high-alkali slurry and breaking; the microcapsule wall material is rolled and squeezed to release the bio-enzyme; and an insertion microwave moisture sensor is used to monitor in real time and control the moisture content of the mixture within ±1% of the optimal moisture content; the microwave moisture sensor sampling frequency is ≥10 times / second, and when the moisture content deviation is >±1%, the system automatically starts spraying water / stirring and drying, with a system response time ≤15s; The adjustment logic for the mixing water temperature is as follows: when the ambient temperature at the construction site is higher than 30℃, use cold water at 5℃~10℃; when the ambient temperature at the construction site is lower than 10℃, use warm water at 20℃~25℃; the optimal moisture content is determined through indoor compaction tests. S4. Fine Mixing: Perform at least two high-lift, high-throw mixing operations on the sprayed mixture to ensure uniform dispersion of the microcapsules. After mixing, a solidified mixture is obtained. During the mixing stage, the mass percentage of aggregates with a particle size greater than 2mm in the mixture is tested. When the aggregate percentage is >55%, a block roller is used in the high-vibration compaction stage. When the aggregate percentage is ≤55%, a smooth-drum roller is used, and the corresponding compaction equipment is directly matched after paving. S5. Paving and Intelligent Control: The solidified mixture is transported to the working surface and paved according to the designed loose paving thickness. During the paving process, the paving thickness and surface flatness are detected in real time using a laser level and ultrasonic sensors. The data is fed back to the paver control system to dynamically adjust the screed height and travel speed. The allowable deviation of the loose paving thickness is ±10mm, and the standard deviation of the paving layer flatness is ≤3mm. When the threshold is exceeded, the paver will automatically reduce its travel speed and raise / lower the screed height. S6. Compaction and compaction degree closed loop: Compaction is carried out in the order of initial static rolling, strong vibratory rolling, and final finishing; during the rolling process, a nuclear density meter is used to detect the compaction degree. If the design requirements are not met, the number of rolling passes is increased. If the compaction degree does not meet the standard, first retest the moisture content of the mixture on site: if the moisture content deviation is > ±1%, transport it back to the mixing plant for temperature-controlled water adjustment and secondary fine mixing; if the moisture content is qualified, add 1 to 2 more passes of strong vibration compaction. Operators of nuclear density meters must hold a radioactive equipment operation certificate. Radiation warning signs must be set up in the work area. The equipment must undergo an annual radiation safety inspection. Short-term single-point testing should be used to reduce the duration of radiation exposure. When there are no radiation testing conditions, the sand filling method can be used to test compaction. S7. Composite Sealing and Curing: Immediately after compaction, spray a layer of fast-setting curing film forming agent or cationic emulsified asphalt onto the surface, then evenly spread dry cement, and statically roll to smooth and form a composite sealing layer; the total construction time of the composite sealing layer should be controlled within 30 minutes after compaction; then cover with geotextile, and take heat preservation or water spraying cooling measures according to the ambient temperature, and keep moist for no less than 7 days.

[0053] This embodiment is applied to a temporary access road for emergency rescue during the rainy season, facing extreme weather windows where rainfall may occur at any time; the soil material on site is ordinary low liquid limit silty clay with an organic matter content of 1.8%, which can be used directly; By utilizing the rain-resistant properties of microcapsules and the instant sealing capability of composite sealant, it is possible to quickly resist rainfall after construction and shorten the maintenance interruption time. In S2, the microcapsule wall material calcium alginate remained intact under unpressurized and low pH conditions. Even if the road surface experienced short-term rainfall, the enzyme molecules were protected within the microcapsules from being washed away or diluted. The enzymes were released when subsequent mechanical compaction and cement hydration increased the pH. The encapsulation rate (E test) was 93%. The S7 composite seal coat uses a process of first spraying fast-setting cationic emulsified asphalt (0.8 kg / m²), followed by a thin layer of cement. After the emulsified asphalt breaks down, it rapidly forms a tough, waterproof membrane that combines with the cement powder to create a sealed surface, providing resistance to rain erosion within one hour of compaction. Curing is achieved by covering with geotextile fabric, and a plastic film is added during rainfall. Two hours after construction, a moderate rain occurred; after the rain, the road surface was inspected and no erosion potholes were found. Core samples were taken according to... The unconfined compressive strength tested after 7 days reached 2.4 MPa, meeting the requirements for temporary access roads. This example fully demonstrates the synergistic effect of microcapsule sustained release and composite sealing layer, greatly expanding the construction window for bio-enzyme road construction during the rainy season and solving the problem of road construction becoming unusable after rain.

[0054] Example 4 addresses the core bottleneck of existing technologies, namely the extremely narrow construction window during the rainy season and the risk of failure upon rain. In traditional bio-enzyme curing construction, if the mixture after spraying enzyme solution is subjected to sudden rainfall, the rainwater will wash away the unbonded fine particles and enzyme solution, forming scour pits and weak interlayers, resulting in the scrapping and rework of the entire structural layer. This embodiment utilizes the encapsulation-compaction triggering mechanism of microcapsules in synergy with the immediate waterproofing effect of the composite seal: calcium alginate microcapsules remain intact under unpressurized and low pH conditions, and even if the surface is washed away by rain, the enzyme molecules are still physically protected inside the microcapsules and are not diluted or lost; cationic emulsified asphalt is sprayed immediately after compaction to form a tough and waterproof membrane, which combines with dry cement to form a sealed surface, and has the ability to resist rain erosion within 1 hour after compaction; a moderate rain suddenly fell 2 hours after construction was completed, and the road surface was not washed away or damaged. The core sample strength reached 2.4 MPa after 7 days. This extends the construction window for bio-enzyme road construction during the rainy season from stopping work when it rains to being able to open to traffic after the rain, which greatly improves the applicability of the technology in rainy areas; The soil material on site is ordinary low liquid limit silty clay with an organic matter content of 1.8%, which can be used directly.

[0055] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A bio-enzyme-cured road paving construction method based on soil waste resource utilization, characterized in that, Includes the following steps: S1. Waste Material Classification, Diagnosis, and Co-processing: Rapidly sample and test waste soil on-site to obtain organic matter content, mineral composition, heavy metal content, and engineering characteristic indicators; when the organic matter mass ratio is greater than 2.5%, add potassium ferrate solution to the soil for chemical oxidation and passivation; when it is determined to be expansive soil, add a composite modifier composed of quicklime and fine sand with a particle size of less than 0.5 mm, and let it sit for 12-24 hours; when the heavy metal content exceeds the background threshold, add active magnesium oxide for adsorption and solidification; after treatment, test the plasticity index and free expansion rate of the modified soil to ensure that the plasticity index is not greater than 28 and the free expansion rate is less than 45%, thus obtaining the base material; S2. Preparation of encapsulated slow-release bio-enzyme composite curing agent: The bio-enzyme stock solution is mixed with sodium alginate solution as the aqueous phase, and injected into calcium chloride solution under stirring to crosslink and form microcapsules encapsulating the enzyme. Then, it is dry-mixed evenly with nano-silica, polypropylene fiber and silicate cement with a strength grade of not less than 42.5 in a predetermined ratio to obtain the composite curing agent. S3, Initial Dry Mixing and Temperature-Controlled Water Adjustment: The base material obtained in S1 is uniformly dry mixed with the dry composite curing agent in S2; the temperature-controlled water adjustment is only water, water is sprayed and mixed, the microwave moisture sensor sampling frequency is ≥10 times / second, when the moisture content deviation is >±1%, the spraying water addition / stirring and drying is automatically started, and the system response time is ≤15s; S4. Fine mixing: Perform at least two high-lift and high-throw mixing operations on the sprayed mixture to ensure uniform dispersion of the microcapsules. After mixing, a solidified mixture is obtained. S5. Paving and Intelligent Control: When the mass ratio of aggregate with a particle size greater than 2mm in the mixture is >55% during the mixing stage, a bump roller is used during the high-vibration compaction stage; when the aggregate is ≤55%, a smooth-drum roller is used, and the corresponding compaction equipment is directly matched after paving. The solidified mixture is transported to the working surface and spread according to the designed loose paving thickness. During the paving process, a laser leveling instrument and an ultrasonic sensor are used to detect the paving thickness and surface flatness in real time, and the data is fed back to the paver control system to dynamically adjust the screed height and travel speed. S6. Compaction and compaction degree closed loop: Compaction is carried out in the order of initial static rolling, strong vibratory rolling, and final finishing; during the rolling process, a nuclear density meter is used to detect the compaction degree. If the design requirements are not met, the number of rolling passes is increased. S7. Composite Sealing and Curing: Immediately after compaction, spray a layer of fast-setting curing film forming agent or cationic emulsified asphalt onto the surface, then evenly spread dry cement, and statically roll to smooth and form a composite sealing layer; the total construction time of the composite sealing layer should be controlled within 30 minutes after compaction; then cover with geotextile, and take heat preservation or water spraying cooling measures according to the ambient temperature, and keep moist for no less than 7 days.

2. The bio-enzyme-cured road paving construction method based on soil waste resource utilization according to claim 1, characterized in that, The potassium ferrate solution in S1 has a mass concentration of 1% to 5%, an admixture amount of 0.5% to 2% of the dry soil mass, and a passivation reaction time of 30 to 60 minutes; the active magnesium oxide admixture amount is 2% to 8% of the dry soil mass.

3. The bio-enzyme-cured road paving construction method based on soil waste resource utilization according to claim 1, characterized in that, In the composite modifier for expansive soil in S1, the amount of quicklime is 2% to 4% of the dry soil mass, and the amount of fine sand is 15% to 25%. After the material is left to stand, the plasticity index of the soil drops to below 28.

4. The bio-enzyme-cured road paving construction method based on soil waste resource utilization according to claim 1, characterized in that, The preparation parameters of the microcapsules in S2 are as follows: sodium alginate solution mass concentration 2% to 4%, calcium chloride solution mass concentration 3% to 5%, cross-linking time 15 to 30 minutes, and the resulting microcapsule particle size range is 50 to 200 micrometers; the amount of nano silica is 0.5% to 2% of the cement mass, and the amount of polypropylene fiber is 0.1% to 0.3% of the total volume of the mixture.

5. The bio-enzyme-cured road paving construction method based on soil waste resource utilization according to claim 1, characterized in that, The temperature control logic for the mixing water in S3 is as follows: when the temperature at the construction site is higher than 30℃, use cold water at 5℃~10℃; when the temperature at the construction site is lower than 10℃, use warm water at 20℃~25℃; the optimal moisture content is determined by indoor compaction test.

6. The bio-enzyme-cured road paving construction method based on soil waste resource utilization according to claim 1, characterized in that, The compaction test frequency described in S6 is one cross section every 50m, with no less than 3 measuring points per cross section; for formal roads, the compaction control standard is no less than 96%, and for temporary construction access roads, the compaction control standard is no less than 93%; if the test value does not meet the standard, 1 to 2 more passes of strong vibration compaction shall be added.

7. The bio-enzyme-cured road paving construction method based on soil waste resource utilization according to claim 1, characterized in that, The fast-setting curing film forming agent mentioned in S7 is a composite aqueous solution of water glass and potassium silicate, with a spraying amount of 0.2 to 0.5 kg / m²; the dry cement spreading amount is 0.3 to 0.8 kg / m²; when the ambient temperature is below 5°C, an insulation blanket is added to the geotextile and an electric heating blanket is laid for heating and curing.

8. The bio-enzyme-cured road paving construction method based on soil waste resource utilization according to claim 1, characterized in that, The rapid detection described in S1 uses a portable near-infrared soil organic matter detector to determine the organic matter content, a handheld X-ray fluorescence analyzer to determine the heavy metal content, and a graduated cylinder method to determine the free expansion rate. In S5, the laser leveling instrument and ultrasonic sensor data are combined with real-time dynamic positioning technology to generate a paving layer thickness cloud map for quality traceability.

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