Gypsum-based multi-source solid waste road base material and preparation method thereof

Abstract

The application discloses a kind of gypsum-based multi-source solid waste road base materials, belong to industrial solid waste resource utilization and road base material technical field.For solving the technical problem that the performance of existing road base material is unstable due to the difficulty in adapting to the fluctuation of multi-source solid waste raw material properties caused by fixed formula, the material provided by the present application comprises gypsum 15%~40%, metallurgical slag component 10%~35%, fly ash 8%~30%, skeleton material 25%~65%, cementing control component 3%~12%, and 1%~10% of the dry mass of gypsum by external dosing of stabilizing agent;Wherein, the gypsum includes one or more of phosphogypsum, desulfurization gypsum, titanium gypsum, fluorogypsum;The reference dry mass is the sum of the dry mass of gypsum, metallurgical slag component, fly ash, skeleton material and cementing control component.The application significantly improves the adaptability of the material to multi-source solid waste raw materials of different sources and different defect degrees through the synergistic compatibility of raw material components and defect index closed-loop control, and is mainly used for road base construction.

Description

Technical Field

[0001] This invention relates to the field of road engineering materials and the resource utilization technology of industrial solid waste. More specifically, this invention relates to a gypsum-based multi-source solid waste road base material and its preparation method. Background Technology

[0002] Gypsum is a byproduct produced in the chemical industry or other industrial processes, with calcium sulfate as its main component. Common types include phosphogypsum, desulfurized gypsum, titanium gypsum, and fluorogypsum.

[0003] Among them, phosphogypsum is an industrial byproduct generated during the wet-process phosphoric acid production process; desulfurization gypsum is a byproduct of the flue gas desulfurization process in coal-fired power plants; titanium gypsum is a waste residue generated during the titanium dioxide production process; and fluorogypsum is a byproduct of the hydrofluoric acid production process. These gypsum-based industrial byproducts, due to their wide availability and large output, have significant economic and environmental value in being utilized as sulfate conditioning components and fine-particle filler components in road base materials.

[0004] However, gypsum-based industrial byproducts are extremely unstable, with significant differences in chemical composition, impurity content, moisture content, and pH value between raw materials from different sources and batches. For example, phosphogypsum typically contains soluble phosphorus, soluble fluorine, and acidic impurities; desulfurized gypsum may contain unreacted calcium carbonate and calcium sulfite; and titanium gypsum and fluorogypsum each have their own specific impurity components. The presence of these impurities can delay the hydration reaction of cementitious materials, affect the formation of early strength, and may lead to substandard water stability and environmental safety (such as excessive leaching of phosphorus, fluorine, and heavy metals). Furthermore, the large fluctuations in initial moisture content can directly affect the workability and ease of construction of the mixture.

[0005] In addition, the raw material properties of commonly used industrial solid wastes such as metallurgical slag (such as steel slag) and fly ash are also extremely unstable: free calcium oxide and free magnesium oxide in metallurgical slag are prone to causing volume expansion in the later stage, while the loss on ignition, water demand ratio and activity index of fly ash directly affect the workability and later strength development of the mixture.

[0006] To address the aforementioned issues, existing gypsum-based road base materials often employ a fixed formulation method. This means that regardless of fluctuations in raw material properties, gypsum is mixed with fly ash, lime, cement, and crushed stone in a fixed mass ratio. The drawback of this method is that it is only applicable to raw materials from a single source with stable properties. When the sources of gypsum, metallurgical slag, and fly ash are complex and their properties fluctuate significantly, the fixed formulation cannot adapt to changes in raw material properties. This can easily lead to significant fluctuations in key performance indicators of the road base material, such as strength, compaction, water stability, and leaching safety, making it difficult to meet engineering requirements.

[0007] Therefore, there is an urgent need to provide a method for preparing road base materials that can dynamically determine the stabilization treatment, material compatibility, and construction mix ratio based on the real-time defect degree of various industrial solid waste raw materials (especially different types of gypsum by-products) in order to improve the performance stability and raw material adaptability of the materials. Summary of the Invention

[0008] One object of the present invention is to provide a gypsum-based multi-source solid waste road base material, which, by reference dry weight, comprises 15% to 40% gypsum, 10% to 35% metallurgical slag, 8% to 30% fly ash, 25% to 65% skeleton material, 3% to 12% cementing and regulating component, and a stabilizing agent externally added at 1% to 10% of the dry weight of gypsum, wherein the gypsum includes one or more of phosphogypsum, desulfurized gypsum, titanium gypsum, and fluorogypsum; The baseline dry mass is the sum of the dry masses of gypsum, metallurgical slag components, fly ash, skeleton materials, and cementation control components; Among them, the gypsum content, the form of metallurgical slag component usage, the fly ash content, the compensation amount of cementitious regulating component, and the actual water addition are based on the gypsum defect index. D PG Metallurgical slag stability risk index D SG and the active water demand index of fly ash D FA The response level is determined.

[0009] Preferably, the unconfined compressive strength of the gypsum-based multi-source solid waste road base material shows an increasing or stable increasing trend after 7 days, 28 days and 90 days of curing, and the water stability coefficient is not less than 0.80; The 7-day unconfined compressive strength of gypsum-based multi-source solid waste road base material shall not be less than 2.5 MPa, the 28-day unconfined compressive strength shall not be less than 4.0 MPa, the dry-wet cycle strength retention rate shall not be less than 0.70, and the freeze-thaw strength retention rate shall not be less than 0.70.

[0010] A method for preparing the gypsum-based multi-source solid waste road base material is provided, comprising the following steps: S1. Detect the raw material defect parameters of gypsum, metallurgical slag components and fly ash respectively; S2. Normalize the raw material defect parameters to a defect index within the range of 0 to 1, including the gypsum defect index. D PG Metallurgical slag stability risk index D SG and the active water demand index of fly ash D FA The larger the value, the greater the adverse effect of the corresponding raw material on the performance stability of the road base material; S3. Set multiple response levels and determine the response level to which each defect index belongs; S4, according to D PG The corresponding response level determines the dosage of gypsum stabilizer and the proportion of gypsum used. Specifically, the dosage of gypsum stabilizer... M S according to Sure, M PG α0 is the dry weight of gypsum, α1 is the dosage coefficient of the basic treatment agent, and α2 is the defect correction coefficient. S5, according to D SG The corresponding response level determines the proportion of metallurgical slag components used as skeleton components and micro powder components, as well as the pretreatment method. S6, according to D FA The corresponding response level determines the amount of fly ash content and the compensation amount of cementitious control components. S7. Based on the optimum moisture content determined by the compaction test, the initial moisture content of each raw material, the water absorption rate of the skeleton material, and the water requirement ratio of fly ash, calculate the actual amount of water to be added. W add : ,in, , , , W opt To determine the optimum moisture content for the compaction test, M d The dry weight of the mixture is the baseline. M i Let the dry mass of the i-th raw material be _____. W i Let be the initial moisture content of the i-th raw material based on dry weight. M j For the j-th type of skeleton material or porous solid waste dry mass, A j,24 The water absorption rate of the j-th type of skeleton material or porous solid waste over 24 hours. or j For the effective water absorption coefficient, M FA For the dry weight of fly ash, K FA The water requirement ratio for fly ash. or FA This is the water requirement correction factor for fly ash; S8 involves mixing, compacting, and curing gypsum, metallurgical slag components, fly ash, skeleton materials, cementation control components, stabilizing agents, and water to obtain road base materials.

[0011] Preferably, the raw material defect parameters of gypsum include soluble phosphorus content, soluble fluorine content, pH value, and initial moisture content based on dry mass; the raw material defect parameters of metallurgical slag components include free calcium oxide content, free magnesium oxide content, expansion rate, and activity index; and the raw material defect parameters of fly ash include loss on ignition, 45 μm sieve residue, water requirement ratio, and activity index.

[0012] Preferably, in step S2, a high-value unfavorable type overlimit function is used. and low-value unfavorable type of overlimit function Normalize the raw material defect parameters; Among them, the gypsum defect index D PG Calculate using the following formula: , in, C P This refers to the soluble phosphorus content of gypsum. C F The soluble fluoride content of gypsum is given by pH, which is the pH value of gypsum. Δ W PG =| W PG - W PG,t |, W PG The initial moisture content of gypsum based on dry weight. W PG,t The target moisture content of gypsum. a 1 , a 2 , a 3 , a 4 As the first weighting coefficient, a 1 The value is 0.25~0.45. a 2 The value is 0.20~0.35. a 3 The value is 0.10~0.25. a 4 It is 0.10~0.25 and a 1 + a 2 + a 3 + a 4 =1; Metallurgical slag stability risk index D SG Calculate using the following formula: , in, f CaO This refers to the free calcium oxide content in the metallurgical slag components. f MgO ε represents the free magnesium oxide content in the metallurgical slag component, and ε represents the expansion rate of the metallurgical slag component. A SG The activity index of metallurgical slag components. b 1 , b 2 , b 3 , b 4 This is the second weighting coefficient. b 1 The value is 0.20~0.40. b 2 The value is 0.15~0.30. b 3 The value is 0.20~0.40. b 4 It is 0.10~0.25 and b 1 + b 2 + b 3 + b 4 =1; When the metallurgical slag composition consists of two or more types of metallurgical slag, the stability risk index of the mixed metallurgical slag is 1. D SG,mix use Calculation determined, oh k Let be the mass proportion coefficient corresponding to the kth type of metallurgical slag; D SG,k Let be the stability risk index of the kth type of single metallurgical slag, and ; Water demand index of fly ash D FA Calculate using the following formula: ,in, LOI This refers to the loss on ignition of fly ash. R 45 This refers to the residue of fly ash on a 45 μm sieve. K FA The water requirement ratio for fly ash. A FA The fly ash activity index, c 1 , c 2 ,c 3 , c 4 This is the third weighting coefficient. c 1 , c 2 , c 3 , c 4 All are 0.15 to 0.35 and c 1 + c 2 + c 3 + c 4 =1.

[0013] Preferably, in step S3, for any defect index D The criteria for determining a graded response are as follows: when D ≤0.30, classified as Level I response; When 0.30 < D ≤0.60, classified as a Level II response; when D >0.60, classified as a Level III response; In step S4, based on the plaster defect index D PG The corresponding response level matches the plaster control plan: 1) When D PG When the concentration is ≤0.30, the gypsum should be directly mixed and used according to the basic mixing ratio; 2) When 0.30 < D PG When the concentration is ≤0.60, increase the dosage of the stabilizing agent and adjust the moisture content of the gypsum simultaneously; 3) When D PG When the concentration is >0.60, increase the dosage of stabilizing agent, reduce the proportion of gypsum, and simultaneously implement at least one of the following treatment processes for gypsum: stabilization treatment, aging treatment, and moisture content adjustment.

[0014] Preferably, in step S5, the metallurgical slag stability risk index is used. D SG The response level limits the usage form of metallurgical slag: 1) When D SG When the concentration is ≤0.30, the metallurgical slag simultaneously serves as both a skeleton component and a micro powder component; 2) When 0.30 < D SGWhen the concentration is ≤0.60, the metallurgical slag is mainly used for its micro powder components, and the mass proportion of the components used as skeleton components shall not exceed 40% of the total mass of the metallurgical slag. 3) When D SG When the value is greater than 0.60, the metallurgical slag must undergo at least one pretreatment process, including aging, grinding, screening, and magnetic separation. Results obtained after pretreatment D SG When the content is still greater than 0.60, the total content of metallurgical slag should not exceed 15% of the reference dry mass of the road base material; In step S6, based on the fly ash activity water requirement index... D FA Response level control of fly ash blending ratio: 1) When D FA When the content of fly ash is ≤0.30, the fly ash content should be 15%~30% of the reference dry mass of the road base material; 2) When 0.30 < D FA When the content of fly ash is ≤0.60, the content of fly ash should be controlled at 10%~25% of the reference dry mass, and the content of cementing control components should be increased to compensate for performance. 3) When D FA When the content is greater than 0.60, the fly ash content shall not exceed 15% of the reference dry mass of the road base material, and the content of at least one binder in slag powder, lime, carbide slag and cement shall be increased simultaneously.

[0015] Preferably, in step S7, the effective water absorption coefficient of the raw material is... or j The calculation formula is: The water absorption time t is selected as 30 min or 60 min; Water demand correction factor for fly ash or FA Based on the fly ash activity coefficient K FA Interval segmentation and value selection: when K FA When the value is between 1.05 and 1.08, or FA Take a value of 0.10~0.15; when K FA When the value is between 1.08 and 1.12, or FA Take a value of 0.15~0.22; when K FA When >1.12, or FATake a value of 0.22~0.30; If the on-site test uses wet basis moisture content, it needs to be converted to dry basis moisture content before being substituted into the calculation. This will determine the required mixing water amount. W add For materials with a moisture content of ≤0, the high moisture content raw materials must first be air-dried, pre-dried, or pre-treated with dry powder before the mixing process can begin.

[0016] Preferably, the method also includes step S9: conducting multiple performance tests on the prepared road base material and using the overall performance feedback coefficient. F Determine whether the overall performance of the mixture meets the standards; Performance feedback coefficient F Calculation formula: Where Ψ(x) = min(1,x), q 7 The measured unconfined compressive strength over 7 days. q 7,t The target unconfined compressive strength at 7 days. q 28 The measured unconfined compressive strength at 28 days. q 28,t The target unconfined compressive strength at 28 days. K s The measured water stability coefficient, K s,t The target water stability coefficient, K dw To measure the strength retention rate during wet and dry cycling, K dw,t To achieve the target dry-wet cycle strength retention rate, K ft Freeze-thaw strength retention rate ，K ft,t The target freeze-thaw strength retention rate, C' P This refers to the phosphorus concentration in the leachate of the molding material. C' F This refers to the fluoride concentration in the leachate of the molding material. C P,lim The limit for phosphorus leaching control. C F,lim For fluorine leaching control limits, when C' P or C' F If the detection limit is lower than that of the corresponding detection method, the detection limit shall be used in the calculation. Among them, when F When the ratio is 1.00, the current mix proportion meets the requirements and can be used directly. When 0.90≤ FWhen the value is less than 1.00, the raw material blending parameters are locally adjusted. when F When the value is less than 0.90, the entire preparation process and proportioning parameters are readjusted.

[0017] Preferably, the stabilizing agent is selected from one or more of phosphorus and fluorine stabilizing components, pH adjusting components, and cementing compensating components; Phosphogypsum is at least one of dihydrate phosphogypsum and aging-pretreated phosphogypsum; The metallurgical slag components are selected from one or more of steel slag powder, steel slag aggregate, and granulated blast furnace slag powder; The fly ash is at least one of low-calcium fly ash and Class II fly ash; The skeleton material is selected from one or more of crushed stone, stone chips, gravel, and manufactured sand; The cementing control component is selected from one or more of lime, cement, carbide slag, slag powder, metakaolin, and silica fume.

[0018] The present invention has at least the following beneficial effects: First, this invention obtains the phosphogypsum defect index by separately detecting the raw material defect parameters of phosphogypsum, metallurgical slag components, and fly ash, and then normalizing them using an out-of-limit function. D PG Metallurgical slag stability risk index ( D SG ) and fly ash activity water demand index ( D FA The dosage of stabilizing agent, the form of metallurgical slag, the dosage of fly ash, the compensation amount of cementing control components, and the actual amount of water added are dynamically adjusted according to the response level (Level I, Level II, Level III) of each index. This ensures that the preparation parameters match the actual quality of the raw materials, thereby transforming the property fluctuations of multi-source industrial solid waste raw materials into preparation parameters that can be graded and corrected by feedback, effectively improving the performance stability of road base materials.

[0019] Secondly, this invention uses a closed-loop feedback correction mechanism to test the unconfined compressive strength, water stability, wet-dry cycle stability, freeze-thaw stability, compaction degree, and leaching safety of road base materials during the trial mixing stage. When any indicator fails to meet the target control requirements, the preparation parameters are corrected according to the failed indicator until all indicators meet the requirements. This allows the method to adapt to phosphogypsum, metallurgical slag, and fly ash raw materials from different sources and with different levels of defects, avoiding the problem of substandard performance caused by raw material fluctuations in a fixed formula.

[0020] Third, this invention improves key performance indicators of road base materials, such as 28-day unconfined compressive strength, water stability coefficient, wet-dry cycle strength retention rate, freeze-thaw strength retention rate, and phosphorus and fluorine leaching concentration, through systematic parameter adjustment by using defect index-based graded response control. Example data shows that, compared to the fixed formulation group, the experimental group exhibited improved 28-day unconfined compressive strength (from 3.8 MPa to 5.1 MPa), water stability coefficient (from 0.73 to 0.85), wet-dry cycle strength retention rate (from 0.66 to 0.78), freeze-thaw strength retention rate (from 0.63 to 0.74), phosphorus leaching concentration (from 0.89 mg / L to 0.42 mg / L), and fluorine leaching concentration (from 7.2 mg / L to 4.1 mg / L).

[0021] Fourth, this invention can improve the adaptability of multi-source industrial solid waste road base materials to raw materials from different sources. The results of adaptability verification for raw materials from different sources show that the fixed formulation group only met the target control requirements under low-defect raw material conditions, while the experimental group met the target control requirements under low-defect, medium-defect, and high-defect raw material conditions. This indicates that this invention can reduce the impact of raw material source fluctuations on the performance of road base materials.

[0022] Other advantages, objectives and features of the present invention will be apparent in part from the following description, and in part from the understanding of those skilled in the art through study and practice of the invention. Attached Figure Description

[0023] Figure 1 This is a flowchart of the method for preparing road base material based on closed-loop control of defect index according to the present invention; Figure 2 This is a diagram showing the defect index response control matrix and preparation parameter mapping relationship of the present invention. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0025] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified. In the description of this invention, the orientation or positional relationship indicated by the terms is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0026] In this invention, gypsum-based solid waste refers to industrial by-product gypsum with calcium sulfate as its main component, including phosphogypsum, desulfurized gypsum, titanium gypsum, fluorogypsum, etc. The preparation method of this invention is universally applicable to all types of gypsum mentioned above. For ease of description and illustration, phosphogypsum is used as a reference in the following examples and comparative examples; however, the scope of protection of this invention is not limited thereto. Those skilled in the art will understand that, based on the same inventive concept, replacing phosphogypsum with other gypsum-based solid waste (such as desulfurized gypsum, titanium gypsum, fluorogypsum, etc.) can achieve the same objective and fall within the scope of protection of this invention.

[0027] When the gypsum is desulfurized gypsum, titanium gypsum, or fluorinated gypsum, one or more of the following can be used as gypsum defect parameters based on its characteristic impurities: unreacted carbonates, sulfites, heavy metal ions, free acids, or soluble fluorine. The dosage of stabilizing agent, the proportion of gypsum used, and the actual amount of water added can be determined according to the same normalization and response level principles.

[0028] <Detection Method> Unless otherwise specified, the detection methods used in this invention are all conventional methods in the field.

[0029] Unconfined compressive strength: can be determined according to the methods specified in the "Test Procedure for Inorganic Binder Stabilized Materials in Highway Engineering" (JTG E51-2009); Compaction test: The optimal moisture content and maximum dry density of the mixture can be determined by the heavy compaction test specified in this specification; Water stability coefficient: calculated by comparing the unconfined compressive strength of the specimen after immersion in water with that of the standard cured specimen; Wet-dry cycle and freeze-thaw cycle: Refer to the relevant methods in the "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete" (GB / T 50082-2009) and adjust them according to the size of the road base material specimens and curing conditions; Leaching test: can be carried out in accordance with the "Leaching Toxicity of Solid Waste - Horizontal Oscillation Method" (HJ 557-2010). The concentrations of phosphorus and fluorine in the leachate can be determined by methods such as ion chromatography. Volume expansion rate: can be determined by pressure steam expansion or water immersion expansion method.

[0030] <Evaluation Standards and Testing Methods> In order to objectively and quantitatively evaluate the technical effects of the present invention, the following unified and repeatable monitoring and evaluation system is established.

[0031] Establish core performance indicators: Strength indicators: 7-day and 28-day unconfined compressive strength; Water stability: water stability coefficient; Durability: Dry-wet cycle strength retention rate, freeze-thaw strength retention rate; Environmental safety: phosphorus and fluoride concentrations in the leachate; Volume stability: 90-day volume expansion rate; Decisive judgment: Only when all the above core performance indicators reach or exceed the target control limits set in Table 1 below, can it be judged as "compliant".

[0032] Table 1 Key Target Control Indicators in the Examples <Parameter Determination Method> To ensure that those skilled in the art can implement this invention, the methods for determining various parameters involved in this invention are described below. 1. Principles for determining control values ​​and risk values In this invention, high-value unfavorable parameters Control value L and risk value U, low-value adverse parameters The target control value E and the lower limit of risk F can be determined according to the following principles: Control value L (or target control value E): can be set with reference to the limits, raw material quality control requirements or engineering target control values ​​in national or industry standards; Risk value U (or lower risk limit F): can be determined based on single-factor pre-tests. That is, under the condition that other conditions remain unchanged, gradually increase the value of a certain defect parameter and observe until a certain key performance indicator (such as 28-day strength, 90-day expansion rate, phosphorus leaching concentration, etc.) fails to meet the target control requirements for the first time. This parameter value is then used as the risk value.

[0033] 2. Parameter setting example To ensure that those skilled in the art can implement this invention, the following description uses specific parameters employed in the embodiments as examples: (1) Defect index of phosphogypsum D PG Calculation parameter settings: Soluble phosphorus content C P Control value C P0 Take 0.50% (referring to the Grade II standard in GB / T 23456-2018 "Phosphogypsum"), risk value C P1 Take 1.00% (the critical value that causes the 28-day unconfined compressive strength to be lower than 3.0 MPa in the preliminary test); Soluble fluoride content C F Control value C F0Take 0.30% (referring to commonly used industry quality control standards), risk value C F1 Take 0.60% (the critical value that caused the fluoride concentration in the leachate to exceed 8.0 mg / L in the preliminary test); pH value: The target control value pH0 is 6.0 (neutral to slightly alkaline, which is conducive to the cementation reaction), and the risk lower limit value pH1 is 3.0 (the critical value that leads to a serious decrease in early strength in the preliminary test). Moisture content deviation Δ W PG : Control value Δ W PG0 Take 2.0% (the range where moisture content fluctuations have a relatively small impact on mixing), risk value Δ W PG1 Take 5.0% (the critical deviation value that would cause the compaction degree to fall below 96% in the preliminary test); (2) Stability risk index of metallurgical slag D SG Calculation parameter settings: Free calcium oxide content f CaO Control value f CaO0 Take 3.0% (referring to the steel slag stability control standard), risk value f CaO1 Take 7.0% (the critical value that caused the 90-day volume expansion rate to exceed 0.50% in the preliminary test); Free magnesium oxide content f MgO Control value f MgO0 Take 5.0%, risk value f MgO1 Take 10.0%; Expansion rate ε: Control value ε0 is 0.50%, risk value ε1 is 2.00%; Activity index A SG Target control value A SG0 Take 75% (the lower limit for meeting activity requirements), the lower risk limit value. A SG1 Take 50% (the critical value where the activity is too low to participate in the cementation reaction); (3) Active water demand index of fly ash D FA Calculation parameter settings: Loss on ignition LOI Control value LOI 0Take 8.0% (refer to the Class II fly ash standard in GB / T 1596-2017 "Fly Ash for Cement and Concrete"), risk value. LOI 1 Take 15.0% (the critical value that leads to a significant decrease in strength in the preliminary test); 45μm sieve residue R 45 Control value R 450 Take 25.0% (Grade II fly ash standard), risk value R 451 Take 45.0%; Water demand ratio K FA Control value K FA0 Take 1.05, risk value K FA1 Take 1.15; Activity index A FA Target control value A FA0 Take 80%, the lower limit of risk. A FA1 Take 60%.

[0034] It should be noted that the specific values ​​of the above parameters are exemplary values ​​given for the purpose of understanding and implementing the present invention. In actual engineering applications, they can be adjusted according to the specific source of raw materials, regional standards and engineering requirements, but the adjusted parameters should remain consistent in the same batch of trial mixes.

[0035] 3. α0, α1, or j and or FA The determination α0 is the basic dosage coefficient of the stabilizing agent, which represents the basic dosage of the stabilizing agent required to meet the phosphorus and fluorine leaching control requirements of low-defect phosphogypsum under basic mix conditions; α1 is the defect correction coefficient, which represents the change in the dosage of the stabilizing agent as a function of the phosphogypsum defect index. D PG The increase in adjustment range due to the increase in size.

[0036] In some implementations, α0 can be based on D PG The pre-test determination of low-defect phosphogypsum with a particle size ≤0.30 was performed, with a value ranging from 0.01 to 0.03; α1 can be determined based on 0.30 < D PG ≤0.60 or D PGPreliminary tests determined that α1 for medium and high defect phosphogypsum with a defect index >0.60 ranged from 0.02 to 0.06. When the soluble phosphorus and soluble fluorine content of phosphogypsum is high, the value of α1 is relatively large; when the defect index of phosphogypsum is low and the leaching safety requirements are easily met, the value of α1 is relatively small.

[0037] or j The effective water absorption coefficient of the skeleton material or porous solid waste during the mixing to compaction time scale can be determined by a short-time water absorption test. Specifically, the short-time water absorption rate of the j-th type of skeleton material or porous solid waste during the mixing to compaction time t can be measured. A j,t and 24-hour water absorption rate A j,24 And determine it according to the following formula: , where t can be determined according to the actual construction organization, usually taken as 30 min or 60 min.

[0038] or FA This is the correction factor for the water demand of fly ash, which can be determined based on the fly ash water demand ratio. K FA Select, when K FA When the value is 1.05~1.08, or FA Take a value of 0.10~0.15; when K FA When the value is between 1.08 and 1.12, or FA Take a value of 0.15~0.22; when K FA When it is greater than 1.12, or FA Take a value of 0.22~0.30. Within the same engineering project, or FA Once determined, consistency should be maintained among similar batches of fly ash.

[0039] <Example 1> Closed-loop preparation under low-defect raw material conditions Objective: To verify that when all three raw materials are within the low defect range, the method of this invention can ensure that the material performance meets the standards; Raw materials: phosphogypsum dihydrate, steel slag powder, granulated blast furnace slag powder, grade II fly ash and graded crushed stone; Preparation steps: S1. Detection of raw material defect parameters: According to the detection method, the various defect parameters of phosphogypsum, metallurgical slag components and fly ash were all found to be at low values ​​or low risk levels. S2. Calculate the defect index: Normalize the parameters detected in S1 to calculate the phosphogypsum defect index. D PG Metallurgical slag stability risk index D SG and the active water demand index of fly ash D FA None greater than 0.30; S3. Determine the response level: Based on the determination criteria, it is determined to be a Level I response. D PG , D SG , D FA All were classified as Level I responses; S4, according to D PG Response level determines phosphogypsum control method: due to D PG ≤0.30 (Level I response), phosphogypsum should be directly added and used according to the basic mix ratio; S5, according to D SG Response level determines the usage form of metallurgical slag: due to D SG ≤0.30 (Level I response), metallurgical slag is used as both a skeleton component and a micro powder component; S6, according to D FA Response level determines fly ash content: due to D FA ≤0.30 (Level I response), the fly ash content is 18% of the baseline dry mass, and no additional compensation cementitious control components are required; S7. Calculate the actual amount of water added. W add Determine the optimum moisture content using conventional compaction tests, and calculate the actual amount of water to be added based on the moisture content of each raw material. S8. Mixing, compacting and curing: Mix, compact and cure according to the reference dry weight ratio in Table 2; Table 2. Reference dry mass ratio of road base materials in Example 1 S9. Performance Testing and Feedback Correction: Performance testing was conducted on the cured specimens. The results are shown in Table 3 below. All indicators met the target control requirements, and the performance feedback coefficient was [not specified]. F =1.00, the current mix proportion is directly used as the construction mix proportion.

[0040] Table 3 Performance results of road base materials in Example 1 <Example 2> Closed-loop regulation under defect conditions of high-phosphorus gypsum Objective: To verify that when the defect index of phosphogypsum is high, the following measures can be taken: D PG Closed-loop regulation can effectively improve material properties; Raw material: Phosphogypsum tested to have a soluble phosphorus content of 0.86%, a soluble fluorine content of 0.34%, a pH value of 4.1, and an initial moisture content of 19.5%. Calculations... D PG >0.60, execute Level III response; Metallurgical slag and fly ash shall be subject to Level I response; Preparation steps: S1. Detection of raw material defect parameters: According to the detection method, the raw material defect parameters of phosphogypsum were measured as follows: soluble phosphorus content. C P =0.86%, soluble fluoride content C F =0.34%, pH=4.1, initial moisture content W PG =19.5%, the detection of metallurgical slag and fly ash were both within the low defect range; S2. Calculation of Defect Index: Using high-value unfavorable and low-value unfavorable exceedance functions, the parameters detected in S1 are normalized to calculate the phosphogypsum defect index. Metallurgical slag stability risk index D SG ≤0.30, fly ash activity water requirement index D FA ≤0.30; S3. Determine the response level: According to the determination criterion "when D > 0.60, it is determined to be a Level III response", D PG Execute a Level III response. D SG and D FA Execute a Level I response; S4, according to D PG Response level determines phosphogypsum control method: due to D PG >0.60 (Level III response), execute Level III response rules: Increase the dosage of stabilizing agent: according to the formula In this embodiment, α0 = 0.02 and α1 = 0.04 are used for calculation. M PG The dry weight of phosphogypsum; Reduce the proportion of phosphogypsum used: reduce the mass ratio of phosphogypsum in road base materials from 28% to 20%; Pretreatment: The phosphogypsum was stabilized and aged for 24 hours to adjust its moisture content to 14.2%; S5, according to D SG Response level determines the usage form of metallurgical slag: due to D SG ≤0.30 (Level I response), metallurgical slag components (steel slag powder and granulated blast furnace slag powder) are used as both skeleton components and micro powder components; S6, according to D FA Response level determines fly ash content: due to D FA ≤0.30 (Level I response), the fly ash content is 18% of the baseline dry mass, and there is no need to increase the amount of cementing control component compensation. S7, Calculate the actual water volume added. W add The optimum moisture content was determined based on the compaction test. W opt , Mixture reference dry mass M d Initial moisture content of each raw material W i 24-hour water absorption rate of the skeleton material (graded crushed stone) A j,24 and effective water absorption coefficient or j and the water requirement ratio of fly ash K FA Water demand correction factor or FA According to the formula Calculate the actual amount of water added; S8. Mixing, compacting and curing: The phosphogypsum treated in step S4 is mixed with metallurgical slag components, fly ash, skeleton materials, cementation control components and water calculated in step S7, compacted and cured according to standard to obtain road base material.

[0041] <Comparative Example 1> The process is basically the same as in Example 2, except that in step S4, no stabilization treatment or moisture content adjustment is performed on the phosphogypsum; it is directly mixed and used according to the basic formula.

[0042] <Comparative Example 2> This is basically the same as Example 2, except that the dosage of the stabilizing agent described in step S4 is adjusted according to the formula. The calculation is replaced with a fixed dosage, which is fixed at 2.0% of the dry weight of phosphogypsum.

[0043] S9. Performance testing and feedback correction: The performance of the specimens after curing in Example 2 and Comparative Examples 1 and 2 was tested, and the test results are shown in Table 4 below.

[0044] Table 4. Performance comparison of high-phosphorus gypsum under defect conditions in Example 2 and Comparative Examples 1-2 As shown in Table 4, Comparative Example 1, due to the lack of treatment for the high-defect phosphogypsum, exhibited severely substandard strength, water stability, and leaching safety. Comparative Example 2, although using a fixed dosage of treatment agent, still did not completely resolve the strength and leaching issues. In contrast, Example 2 of this invention dynamically adjusted the dosage of treatment agent and phosphogypsum based on the defect index, ensuring that all indicators met the target control requirements. This demonstrates that under conditions of high phosphogypsum defects, the treatment agent dosage and phosphogypsum dosage are effective. D PG Graded regulation is key to improving the overall performance of materials.

[0045] <Example 3> Closed-loop regulation under high metallurgical slag stability risk conditions Objective: To verify the effectiveness of metallurgical slag stability risk index when it is high. D SG Closed-loop regulation can effectively suppress subsequent volume expansion; Raw materials: The metallurgical slag composition analysis results showed a free calcium oxide content of 6.2%, a free magnesium oxide content of 5.9%, an expansion rate of 1.35%, and an activity index of 68%. Phosphogypsum and fly ash were within the low defect range. Preparation steps: S1. Detection of raw material defect parameters: According to the detection method, the raw material defect parameters of the metallurgical slag components are as follows: Free calcium oxide content f CaO =6.2%, free magnesium oxide content f MgO =5.9%, expansion rate ε=1.35%, activity index A SG =68%; S2. Calculation of Defect Index: The metallurgical slag stability risk index is calculated by normalizing using an out-of-limit function. D SG >0.60; phosphogypsum defect index D PG and the active water demand index of fly ash D FA None greater than 0.30; S3. Determine the response level: based on the determination criteria. D SG Execute a Level III response;D PG and D FA Execute a Level I response; S4 according to D PG Response level determines phosphogypsum control method: due to D PG ≤0.30 (Level I response), phosphogypsum should be used according to the basic formula ratio; S5, according to D SG Response level determines the usage form of metallurgical slag: due to D SG >0.60 (Level III response), implement the following measures: Pretreatment: The metallurgical slag was aged, screened, and ground. After treatment, the free calcium oxide content decreased to 4.1%, the free magnesium oxide content decreased to 4.8%, the expansion rate decreased to 0.72%, and the activity index increased to 70%. The results were then recalculated. D SG It is 0.28; Limited use: after processing D SG Although it has been downgraded to Level I, according to the rules, the metallurgical slag components are mainly in the form of fine powder, and the use of the skeleton components is limited. S6, according to D FA Response level determines fly ash content: due to D FA ≤0.30 (Level I response), fly ash content is 18% of the baseline dry mass; S7. Calculate the actual amount of water added. W add Based on the optimum moisture content determined by the compaction test and the parameters of each raw material, calculate the actual amount of water to be added according to the formula. S8. Mixing, compacting and curing: Mix the pretreated metallurgical slag with other raw materials and water, compact and cure according to standard. S9. Performance testing and feedback correction: Perform performance testing on the cured specimens.

[0046] <Comparative Example 3> The process is basically the same as in Example 3, except that in step S5, the metallurgical slag is not pretreated and is used directly in a high-proportion skeleton form.

[0047] <Comparative Example 4> The process is basically the same as in Example 3, except that in step S5, only the metallurgical slag is aged and screened, without grinding; after treatment... D SG =0.45, metallurgical slag is still used in part of the skeleton form (accounting for 50%).

[0048] The performance of the specimens after curing in Example 3 and Comparative Examples 3 and 4 was tested, and the test results are shown in Table 5 below.

[0049] Table 5 Performance comparison of Example 3 and Comparative Examples 3-4 under high metallurgical slag stability risk conditions As shown in Table 5, Comparative Example 3, without treatment, exhibited severely excessive volume expansion; Comparative Example 4, although partially treated, showed improved volume stability, but still exceeded the limit; Example 3, through comprehensive pretreatment and strict usage limits, successfully controlled the 90-day volume expansion rate to 0.18%, while ensuring good strength and durability, proving... D SG The effectiveness of the control measures.

[0050] <Example 4> Closed-loop regulation under conditions of high fly ash water demand and low activity Objective: To verify that when the water demand index of fly ash is high, the following measures can be taken: D FA Closed-loop control can effectively improve compaction and strength; Raw materials: The test results of fly ash were 8.6% loss on ignition, 41% residue on 45µm sieve, water requirement ratio of 1.14, activity index of 61%, and phosphogypsum and metallurgical slag were in the low defect range. Preparation steps: S1. Detection of raw material defect parameters: According to the detection method, the raw material defect parameters of fly ash were measured as follows: Loss on ignition LOI =8.6%, 45µm sieve residue R 45 =41%, water demand ratio K FA =1.14, activity index A FA =61%; S2. Calculate the defect index and normalize it using the out-of-limit function to obtain the fly ash activity water requirement index. D FA >0.60; phosphogypsum defect index D PG Stability Risk Index of Metallurgical Slag D SG None greater than 0.30; S3. Determine the response level: based on the determination criteria. D FA Execute a Level III response; D PG and D SG Execute a Level I response; S4, according to D PG Response level determines phosphogypsum control method: due to D PG ≤0.30 (Level I response), phosphogypsum should be used according to the basic formula ratio; S5, according to D SG Response level determines the usage form of metallurgical slag: due to D SG ≤0.30 (Level I response), metallurgical slag is used as both a skeleton and a micro powder component; S6, according to D FA Response level determines fly ash content: due to D FA >0.60 (Level III response), implement the following measures: Limit the amount of fly ash: Control the amount of fly ash to 10% of the reference dry weight; Compensating for cementitious components: increasing the content of slag powder and cement; S7. Calculate the actual amount of water added. W add The actual water addition is calculated according to the formula, where the water requirement correction factor for fly ash is included. or FA Based on a water demand ratio of 1.14, a value of 0.25 is selected to adjust the water supply. S8. Mixing, compacting and curing: Mix, compact and cure all raw materials and water according to standard. S9. Performance testing and feedback correction: Perform performance testing on the cured specimens.

[0051] <Comparative Example 5> The process is basically the same as in Example 4, except that in step S7, the amount of water added is not adjusted according to the water requirement ratio of fly ash, and the conventional optimal moisture content is directly used for mixing.

[0052] <Comparative Example 6> The process is basically the same as in Example 4, except that the fly ash content (20%) is not limited in step S6, and the cementing control component is not increased.

[0053] The performance of the specimens after curing in Example 4 and Comparative Examples 5 and 6 was tested, and the test results are shown in Table 6 below.

[0054] Table 6. Performance comparison of Example 4 and Comparative Examples 5-6 under conditions of high fly ash water requirement and low activity. Table 6 shows that Comparative Example 5 had low compaction and unqualified strength due to insufficient water addition; Comparative Example 6, although with a high moisture content, had substandard water stability due to high fly ash content and lack of compensation for cementing components; Example 4, by limiting the dosage, compensating for cementing components, and correcting the water addition, achieved the required compaction, strength, and water stability, proving that... D FA The control scheme can effectively overcome the problem of high water demand and low activity in fly ash.

[0055] <Example 5> Comparison of single-item correction and complete closed-loop regulation Objective: To compare the effects of complete closed-loop regulation with that of single-item correction, and to demonstrate the overall advantage of the three-index synergistic regulation of this invention; Method: Use the same batch of raw materials with medium to high defect levels (phosphogypsum, metallurgical slag, and fly ash are all of medium to high defect levels). Preparation steps: S1~S2: Detected and calculated D PG , D SG , D FA All fall within the Level II or Level III response range; S3: Determine the response level for each defect index; S4~S6: Adjust the dosage and usage ratio of phosphogypsum stabilizing agent, the pretreatment method and usage form of metallurgical slag, the dosage of fly ash and the compensation amount of cementing components according to the response level of each defect index. S7: Calculate and correct the actual amount of water to be added according to the formula; S8~S9: Mixing, compacting, curing, and performance testing.

[0056] <Comparative Example 7> It is basically the same as Example 5, except that: only according to D PG Regulation, and D SG and D FA Not involved in the adjustment (handled as a Level I response).

[0057] <Comparative Example 8> It is basically the same as Example 5, except that: only according to D FA Regulation, and D PG and D SG Not involved in the adjustment (handled as a Level I response).

[0058] <Fixed Formula Group> This is basically the same as Example 5, except that all three groups of raw materials are prepared using the same fixed ratio and the same amount of water. The formula and water content are as follows: based on the baseline dry weight, 28% phosphogypsum, 8% steel slag powder, 12% granulated blast furnace slag powder, 18% fly ash, 30% graded crushed stone, and 4% cementitious control component; the stabilizing agent is added externally at a fixed amount of 2.0% of the dry weight of phosphogypsum; the actual mixing moisture content is fixed at 9.9%. This fixed formula set is not based on calculations. D PG , D SG , D FA No adjustments will be made to the response level, nor will the actual amount of water added be corrected.

[0059] The performance of the specimens after curing in Example 5 and Comparative Examples 7 and 8 was tested, and the test results are shown in Table 7 below.

[0060] Table 7. Comparison results of single-item correction and complete closed-loop control in Example 5 and Comparative Examples 7-8 As shown in Table 7, the performance of the fixed formulation group deteriorated across the board. Although Comparative Example 7 (treating only phosphogypsum) and Comparative Example 8 (correcting only the amount of water added) showed some improvement in certain indicators, several key indicators still failed to meet the standards due to the lack of synergistic regulation of the defects of other raw materials. In contrast, the complete closed-loop regulation group of Example 5 simultaneously coordinated the responses of the three defect indices, enabling all performance indicators to reach their optimal levels and consistently meet the standards, demonstrating the significant overall superiority of the synergistic regulation of the present invention.

[0061] <Example 6> Adaptability verification of raw materials from different sources Objective: To verify the broad adaptability of the method of the present invention to raw materials with different degrees of defects, and to compare it with a fixed formulation scheme; Methods: Three combinations of raw materials from different sources and with different defect levels were selected (A: low defect, B: medium defect, C: high defect). The specific defect indices are shown in Table 8 below.

[0062] Table 8 Defect Index of Raw Material Combinations from Different Sources Preparation steps: Fixed formulation group: All three groups of raw materials are prepared using the same fixed ratio and the same amount of water (the specific details are the same as above).

[0063] Experimental group: For the three groups of raw materials, the stabilizing agent, metallurgical slag usage form, fly ash content, cementing components and actual water addition were dynamically adjusted according to their respective defect indices in steps S1 to S9 of Examples 1 to 5.

[0064] The fixed formulation group and the experimental group were prepared according to the above three combinations of raw materials from different sources and with different defect levels, and their indicators were tested. The results are shown in Table 9 below.

[0065] Table 9. Comparison of results between the fixed formulation and the experimental group under different raw material sources. The results are shown in Table 9. The fixed formulation group barely met the standard under low-defect raw material A, and the performance deteriorated completely under medium and high-defect raw materials. In contrast, the experimental group of the method of the present invention was able to prepare products with all performances fully met under three groups of raw materials with different defect levels, demonstrating extremely strong raw material adaptability.

[0066] The structural stability of the gypsum-based multi-source solid waste road base material described in this invention, after mixing, compaction, and curing, is comprehensively evaluated through the aforementioned mechanical properties, water resistance, cyclic stability, and leaching safety. As shown in Examples 1-6 and the corresponding comparative examples, the road base material prepared using the method of this invention exhibits a continuous or stable increasing trend in unconfined compressive strength after 7 days, 28 days, and 90 days of curing. Furthermore, the water stability coefficient, wet-dry cycle strength retention rate, freeze-thaw strength retention rate, and phosphorus and fluorine leaching concentrations all meet the preset target requirements, indicating that it has formed a stable structural system capable of meeting the long-term use requirements of road base materials.

[0067] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A gypsum-based multi-source solid waste road base material, characterized in that, Based on the reference dry weight, it includes 15%~40% gypsum, 10%~35% metallurgical slag components, 8%~30% fly ash, 25%~65% skeleton material, 3%~12% cementing and regulating components, and stabilizing agents added externally at 1%~10% of the dry weight of gypsum. Among them, gypsum includes one or more of phosphogypsum, desulfurized gypsum, titanium gypsum, and fluorogypsum. The baseline dry mass is the sum of the dry masses of gypsum, metallurgical slag components, fly ash, skeleton materials, and cementation control components; Among them, the gypsum content, the form of metallurgical slag component usage, the fly ash content, the compensation amount of cementitious regulating component, and the actual water addition are based on the gypsum defect index. D PG Metallurgical slag stability risk index D SG and the active water demand index of fly ash D FA The response level is determined.

2. The gypsum-based multi-source solid waste road base material as described in claim 1, characterized in that, The unconfined compressive strength of gypsum-based multi-source solid waste road base material showed an increasing or stable increasing trend after 7d, 28d and 90d curing, and the water stability coefficient was not less than 0.

80. The 7-day unconfined compressive strength of gypsum-based multi-source solid waste road base material shall not be less than 2.5 MPa, the 28-day unconfined compressive strength shall not be less than 4.0 MPa, the dry-wet cycle strength retention rate shall not be less than 0.70, and the freeze-thaw strength retention rate shall not be less than 0.

70.

3. The method for preparing gypsum-based multi-source solid waste road base material as described in any one of claims 1 to 2, characterized in that, Includes the following steps: S1. Detect the raw material defect parameters of gypsum, metallurgical slag components and fly ash respectively; S2. Normalize the raw material defect parameters to a defect index within the range of 0 to 1, including the gypsum defect index. D PG Metallurgical slag stability risk index D SG and the active water demand index of fly ash D FA The larger the value, the greater the adverse effect of the corresponding raw material on the performance stability of the road base material; S3. Set multiple response levels and determine the response level to which each defect index belongs; S4, according to D PG The corresponding response level determines the dosage of gypsum stabilizer and the proportion of gypsum used. Specifically, the dosage of gypsum stabilizer... M S according to Sure, M PG α0 is the dry weight of gypsum, α1 is the dosage coefficient of the basic treatment agent, and α2 is the defect correction coefficient. S5, according to D SG The corresponding response level determines the proportion of metallurgical slag components used as skeleton components and micro powder components, as well as the pretreatment method. S6, according to D FA The corresponding response level determines the amount of fly ash content and the compensation amount of cementitious control components. S7. Based on the optimum moisture content determined by the compaction test, the initial moisture content of each raw material, the water absorption rate of the skeleton material, and the water requirement ratio of fly ash, calculate the actual amount of water to be added. W add : ,in, , , , W opt To determine the optimum moisture content for the compaction test, M d The dry weight of the mixture is the baseline. M i Let the dry mass of the i-th raw material be _____. W i Let be the initial moisture content of the i-th raw material based on dry weight. M j For the j-th type of skeleton material or porous solid waste dry mass, A j,24 The water absorption rate of the j-th type of skeleton material or porous solid waste over 24 hours. η j For the effective water absorption coefficient, M FA For the dry weight of fly ash, K FA The water requirement ratio for fly ash. η FA This is the water requirement correction factor for fly ash; S8 involves mixing, compacting, and curing gypsum, metallurgical slag components, fly ash, skeleton materials, cementation control components, stabilizing agents, and water to obtain road base materials.

4. The preparation method of gypsum-based multi-source solid waste road base material as described in claim 3, characterized in that, The raw material defect parameters of gypsum include soluble phosphorus content, soluble fluorine content, pH value, and initial moisture content based on dry mass. The raw material defect parameters of metallurgical slag components include free calcium oxide content, free magnesium oxide content, expansion rate, and activity index. The raw material defect parameters of fly ash include loss on ignition, 45 μm sieve residue, water requirement ratio, and activity index.

5. The preparation method of gypsum-based multi-source solid waste road base material as described in claim 4, characterized in that, In step S2, a high-value unfavorable type of overlimit function is used. and low-value unfavorable type of overlimit function Normalize the raw material defect parameters; Among them, the gypsum defect index D PG Calculate using the following formula: ,in, C P This refers to the soluble phosphorus content of gypsum. C F The soluble fluoride content of gypsum is given by pH, which is the pH value of gypsum. Δ W PG =| W PG - W PG,t |, W PG The initial moisture content of gypsum based on dry weight. W PG,t The target moisture content of gypsum. a 1 , a 2 , a 3 , a 4 As the first weighting coefficient, a 1 The value is 0.25~0.

45. a 2 The value is 0.20~0.

35. a 3 The value is 0.10~0.

25. a 4 It is 0.10~0.25 and a 1 + a 2 + a 3 + a 4 =1; Metallurgical slag stability risk index D SG Calculate using the following formula: ,in, f CaO This refers to the free calcium oxide content in the metallurgical slag components. f MgO ε represents the free magnesium oxide content in the metallurgical slag component, and ε represents the expansion rate of the metallurgical slag component. A SG The activity index of metallurgical slag components. b 1 , b 2 , b 3 , b 4 This is the second weighting coefficient. b 1 The value is 0.20~0.

40. b 2 The value is 0.15~0.

30. b 3 The value is 0.20~0.

40. b 4 It is 0.10~0.25 and b 1 + b 2 + b 3 + b 4 =1; When the metallurgical slag composition consists of two or more types of metallurgical slag, the stability risk index of the mixed metallurgical slag is 1. D SG,mix use Calculation determined, ω k Let be the mass proportion coefficient corresponding to the kth type of metallurgical slag; D SG,k Let be the stability risk index of the kth type of single metallurgical slag, and ; Water demand index of fly ash D FA Calculate using the following formula: ,in, LOI This refers to the loss on ignition of fly ash. R 45 This refers to the residue of fly ash on a 45 μm sieve. K FA The water requirement ratio for fly ash. A FA The fly ash activity index, c 1 , c 2 , c 3 , c 4 The third weighting coefficient, c 1 , c 2 , c 3 , c 4 All are 0.15 to 0.35 and c 1 + c 2 + c 3 + c 4 =1.

6. The preparation method of gypsum-based multi-source solid waste road base material as described in claim 3, characterized in that, In step S3, for any defect index D The criteria for determining a graded response are as follows: when D ≤0.30, classified as Level I response; When 0.30 < D ≤0.60, classified as a Level II response; when D >0.60, classified as a Level III response; In step S4, based on the plaster defect index D PG The corresponding response level matches the plaster control plan: 1) When D PG When the concentration is ≤0.30, the gypsum should be directly mixed and used according to the basic mixing ratio; 2) When 0.30 < D PG When the concentration is ≤0.60, increase the dosage of the stabilizing agent and adjust the moisture content of the gypsum simultaneously; 3) When D PG When the concentration is >0.60, increase the dosage of stabilizing agent, reduce the proportion of gypsum, and simultaneously implement at least one of the following treatment processes for gypsum: stabilization treatment, aging treatment, and moisture content adjustment.

7. The preparation method of gypsum-based multi-source solid waste road base material as described in claim 6, characterized in that, In step S5, based on the metallurgical slag stability risk index D SG The response level limits the usage form of metallurgical slag: 1) When D SG When the concentration is ≤0.30, the metallurgical slag simultaneously serves as both a skeleton component and a micro powder component; 2) When 0.30 < D SG When the concentration is ≤0.60, the metallurgical slag is mainly used for its micro powder components, and the mass proportion of the components used as skeleton components shall not exceed 40% of the total mass of the metallurgical slag. 3) When D SG When the value is greater than 0.60, the metallurgical slag must undergo at least one pretreatment process, including aging, grinding, screening, and magnetic separation. Results obtained after pretreatment D SG When the content is still greater than 0.60, the total content of metallurgical slag should not exceed 15% of the reference dry mass of the road base material; In step S6, based on the fly ash activity water requirement index... D FA Response level control of fly ash blending ratio: 1) When D FA When the content of fly ash is ≤0.30, the fly ash content should be 15%~30% of the reference dry mass of the road base material; 2) When 0.30 < D FA When the content of fly ash is ≤0.60, the content of fly ash should be controlled at 10%~25% of the reference dry mass, and the content of cementing control components should be increased to compensate for performance. 3) When D FA When the content is greater than 0.60, the fly ash content shall not exceed 15% of the reference dry mass of the road base material, and the content of at least one binder in slag powder, lime, carbide slag and cement shall be increased simultaneously.

8. The preparation method of gypsum-based multi-source solid waste road base material as described in claim 3, characterized in that, In step S7, the effective water absorption coefficient of the raw material is... η j The calculation formula is: The water absorption time t is selected as 30 min or 60 min; Water demand correction factor for fly ash η FA Based on the fly ash activity coefficient K FA Interval segmentation and value selection: when K FA When the value is between 1.05 and 1.08, η FA Take a value of 0.10~0.15; when K FA When the value is between 1.08 and 1.12, η FA Take a value of 0.15~0.22; when K FA When >1.12, η FA Take a value of 0.22~0.30; If the on-site test uses wet basis moisture content, it needs to be converted to dry basis moisture content before being substituted into the calculation. This will determine the required mixing water amount. W add For materials with a moisture content of ≤0, the high moisture content raw materials must first be air-dried, pre-dried, or pre-treated with dry powder before the mixing process can begin.

9. The preparation method of gypsum-based multi-source solid waste road base material as described in claim 3, characterized in that, It also includes step S9: conducting multiple performance tests on the prepared road base material, and using the overall performance feedback coefficient. F Determine whether the overall performance of the mixture meets the standards; Performance feedback coefficient F Calculation formula: Where Ψ(x) = min(1,x), q 7 The measured unconfined compressive strength over 7 days. q 7,t The target unconfined compressive strength at 7 days. q 28 The measured unconfined compressive strength at 28 days. q 28,t The target unconfined compressive strength at 28 days. K s The measured water stability coefficient, K s,t The target water stability coefficient, K dw To measure the strength retention rate during wet and dry cycling, K dw,t To achieve the target dry-wet cycle strength retention rate, K ft Freeze-thaw strength retention rate ，K ft,t The target freeze-thaw strength retention rate, C' P This refers to the phosphorus concentration in the leachate of the molding material. C' F This refers to the fluoride concentration in the leachate of the molding material. C P,lim The limit for phosphorus leaching control. C F,lim For fluorine leaching control limits, when C' P or C' F If the detection limit is lower than that of the corresponding detection method, the detection limit shall be used in the calculation. Among them, when F When the ratio is 1.00, the current mix proportion meets the requirements and can be used directly. When 0.90≤ F When the value is less than 1.00, the raw material blending parameters are locally adjusted. when F When the value is less than 0.90, the entire preparation process and proportioning parameters are readjusted.

10. The method for preparing gypsum-based multi-source solid waste road base material as described in claim 3, characterized in that, The stabilizing agent is selected from one or more of the following: phosphorus and fluorine stabilizing components, pH adjusting components, and cementing compensation components; Phosphogypsum is at least one of dihydrate phosphogypsum and aging-pretreated phosphogypsum; The metallurgical slag components are selected from one or more of steel slag powder, steel slag aggregate, and granulated blast furnace slag powder; The fly ash is at least one of low-calcium fly ash and Class II fly ash; The skeleton material is selected from one or more of crushed stone, stone chips, gravel, and manufactured sand; The cementing control component is selected from one or more of lime, cement, carbide slag, slag powder, metakaolin, and silica fume.

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