Controllable low-strength material for road base and preparation method thereof

Abstract

The application relates to the technical field of building material processing, in particular to controllable low-strength material for road surface base and a preparation method thereof, which comprises the following steps: selecting bottom ash of waste incineration, carbide slag, blast furnace slag, fly ash and water as preparation raw materials of the controllable low-strength material for road surface base, stirring the bottom ash of waste incineration, the carbide slag, the blast furnace slag and the fly ash to obtain dry material mixture, then adding water to stir to obtain slurry, and analyzing the unevenness of the material in each period and the stirring fluctuation index in the slurry preparation process to judge the stirring stop time. The application can improve the preparation efficiency of the controllable low-strength material for road surface base, and improve the uniformity of the slurry and the stability of the material performance.

Description

Technical Field

[0001] This application relates to the field of building material processing technology, specifically to a controllable low-strength material for road base courses and its preparation method. Background Technology

[0002] Traditional controllable low-strength materials mainly consist of cement, fly ash, fine aggregate, water, and admixtures, and are highly dependent on non-renewable resources such as cement and natural sand. Meanwhile, the construction of road base and subbase courses typically consumes large amounts of aggregate. Using waste incineration ash as fine aggregate in conjunction with solid waste cementitious materials to prepare controllable low-strength materials for road base courses can address the low resource utilization rate of waste incineration ash and reduce the demand for cement and natural aggregates in highway base course construction, thus possessing significant practical implications.

[0003] In the preparation of controllable low-strength materials, existing technologies typically rely on fixed stirring times or monitoring equipment operation to determine whether the raw materials are uniformly mixed. However, due to differences in particle size and density among different raw materials, the stirring time required for the slurry to achieve a uniform mixture varies under different proportions. Furthermore, during the stirring process, some fine particles easily adhere to the mixer blades after encountering water. Even if the raw materials are basically uniformly mixed, these adhering particles can still cause fluctuations in the equipment's operating data, thus interfering with the judgment of the true mixing state. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this application is to provide a controllable low-strength material for road base courses and its preparation method. The specific technical solution adopted is as follows: This application provides a method for preparing a controllable low-strength material for road base courses, including the following steps: Waste incineration bottom ash, carbide slag, blast furnace slag, fly ash and water are selected as raw materials for the preparation of controllable low strength materials for road base. Waste incineration bottom ash, carbide slag, blast furnace slag and fly ash are mixed to obtain dry material mixture, and then water is added and mixed to obtain slurry. At the start of slurry mixing, current and vibration data of the mixer are acquired. The discrete characteristics and abrupt changes of current and vibration data in each cycle during the mixing process are analyzed to obtain the dispersion unevenness of each cycle. By utilizing the changing trend of dispersion unevenness in different cycles, combined with the similarity between current and vibration data in the cycle and the fluctuation of the similarity, the mixing fluctuation index of each cycle is obtained. Based on the mixing fluctuation index of qualified materials during the mixing process, a qualified value range is constructed to determine the time of stopping the mixing. After the slurry is mixed, it is poured into a mold to form a shape, and then demolded and cured to obtain a controllable low-strength material for road base.

[0005] Preferably, the following components are used: 100 parts of waste incineration bottom ash; 1-5 parts of calcium carbide slag; 10-20 parts of blast furnace slag; and 5-15 parts of fly ash.

[0006] The preferred formula for obtaining the dispersion unevenness of each period is: In the formula, Let be the dispersion unevenness of the i-th period; Let be the first discrete value of the i-th period, where the first discrete value is the sum of the discreteness of the current data and the discreteness of the vibration data within the i-th period; is the average percentage of mutations in the i-th cycle; norm() is the normalization function.

[0007] Preferably, the ratio of the number of abrupt changes in the current data to the total number of current data and the ratio of the number of abrupt changes in the vibration data to the total number of vibration data are calculated in the i-th period, and the average of the two ratios is taken as the average percentage of abrupt changes in the i-th period.

[0008] Preferably, the formula for obtaining the stirring fluctuation index for each period is: In the formula, Let be the stirring fluctuation index for the i-th period. Let be the dispersion unevenness in the i-th period. The first slope of the i-th period; The second discrete value in the i-th period; Let be the DTW similarity for the i-th period; These are the parameter tuning coefficients.

[0009] Preferably, the i-th period and the preceding consecutive periods are taken as the detection segment of the i-th period, and all dispersion non-uniformity lines within the detection segment are fitted, and the absolute value of the slope of the fitted line is taken as the first slope of the i-th period. The DTW similarity between the current data and vibration data in the i-th cycle is statistically analyzed, and the dispersion of the DTW similarity corresponding to each cycle in the detection segment of the i-th cycle is calculated as the second discrete value of the i-th cycle.

[0010] Preferably, the stirring fluctuation index of the last cycle in each qualified stirring process is calculated, and the minimum and maximum values ​​of all stirring fluctuation indices calculated from all qualified stirring processes are used to form the qualified value range, wherein the qualified stirring process is the slurry stirring process corresponding to the pre-selected qualified material.

[0011] Preferably, the determination of the stirring stop time is as follows: if the stirring fluctuation index of the current cycle and several consecutive previous cycles are all within the qualified value range, then stirring is stopped; otherwise, stirring continues.

[0012] Preferably, after demolding, the product is placed in a constant temperature and humidity chamber at 20°C and 95% relative humidity for curing.

[0013] This application embodiment also provides a controllable low-strength material for road base courses, which is prepared by any of the steps of the method for preparing a controllable low-strength material for road base courses described in any one of the claims, wherein the mass of water accounts for 30% of the total mass of solid raw materials in the raw materials for preparing the controllable low-strength material.

[0014] As can be seen from the above, the controllable low-strength material for road base courses and its preparation method provided in this application have at least the following beneficial effects: This application constructs a dispersion non-uniformity index, thereby enabling a preliminary assessment of the disorder of the material dispersion state during slurry mixing, and constructs a mixing fluctuation index to combine the fluctuation of the mixing state in multiple adjacent periods, thereby comprehensively assessing the material mixing state. This application utilizes the characteristic of calcium carbide slag being rich in Ca(OH)2 as an alkali activator, thereby effectively avoiding the problem of matrix expansion and cracking caused by the reaction of residual metallic aluminum in the bottom ash of waste incineration with traditional alkali activators to generate hydrogen gas; using calcium carbide slag, blast furnace slag, and fly ash as cementing materials, it can achieve a complete replacement of cement, thereby helping to reduce carbon emissions.

[0015] This application addresses the problem in existing technologies for preparing controllable low-strength materials where the inability to accurately assess the uniformity of material mixing affects the material's performance. This application constructs a stirring fluctuation index and a qualified value range, enabling the assessment of the current stirring state based on historical qualified stirring processes. This allows for timely cessation of stirring when the material is basically uniformly mixed, avoiding under- or over-mixing, thereby improving the uniformity of the slurry and the stability of material properties. This provides a reliable technical guarantee for the large-scale resource utilization of waste incineration bottom ash. Attached Figure Description

[0016] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This application provides a flowchart of the steps involved in preparing a controllable low-strength material for road base courses. Detailed Implementation

[0018] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a controllable low-strength material for road base courses and its preparation method proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0019] Unless otherwise specified and limited, terms such as “comprising,” “including,” or any other variations thereof are intended to cover a non-exclusive inclusion, such that a circuit structure, article, or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase “comprising one…” does not exclude the presence of other identical elements in the article or device that includes said element. Furthermore, the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0020] The following description, in conjunction with the accompanying drawings, details a specific scheme for a controllable low-strength material for road base courses and its preparation method provided in this application.

[0021] Please see Figure 1 It illustrates a flowchart of a method for preparing a controllable low-strength material for road base courses according to an embodiment of this application, including the following steps: This application uses waste incineration bottom ash as fine aggregate and carbide slag, blast furnace slag, and fly ash as solid waste cementing materials to prepare controllable low-strength materials. Carbide slag is rich in Ca(OH)2 (calcium hydroxide), which can partially ionize OH-. - It can also provide a large amount of Ca 2 + A high-alkali, high-calcium environment is created to stimulate the reactivity of blast furnace slag and fly ash, resulting in an alkali-activated reaction that generates gel products, promoting strength development. Simultaneously, ball milling of the waste incineration bottom ash improves its fineness, optimizes particle size distribution, and forms a compact packing structure, enhancing density. By increasing the addition amounts of carbide slag, blast furnace slag, and fly ash, and thoroughly mixing all raw materials, the alkali-activated reaction is further promoted, thereby improving the unconfined compressive strength of the controllable low-strength material and achieving the strength standards for road base materials.

[0022] The raw materials used in this application for the preparation of controllable low-strength materials for road base courses include: waste incineration bottom ash, carbide slag, blast furnace slag, fly ash and water, with water accounting for 30% of the total mass of all solid raw materials.

[0023] Example 1 The solid raw materials described in this embodiment are specifically composed of the following components by weight: 100 parts of waste incineration bottom ash; 1 part of calcium carbide slag; 15 parts of blast furnace slag; and 10 parts of fly ash.

[0024] S1: Pretreatment of bottom ash from waste incineration.

[0025] The waste incineration bottom ash dried at 105℃ for 9 hours was passed through a 4.75mm square hole sieve to remove the residue on the sieve. Then, the sieved waste incineration bottom ash was put into a cement test mill for ball milling for 15 minutes. The ball-to-material ratio was approximately 6:1 to ensure that the fineness modulus of the waste incineration bottom ash after ball milling was 1.7 and the particle size of the bottom ash was ≤2.36mm.

[0026] S2: Mix multiple raw materials to obtain a slurry.

[0027] The pretreated waste incineration bottom ash, carbide slag, blast furnace slag and fly ash are put into a cement mortar mixer for dry mixing. The mixing time is 1 minute and the mixing speed is 50 rpm. After the dry mixing is completed, water is added and mixed to obtain a controllable low-strength material slurry. The mixing speed after adding water is the same as the speed during dry mixing.

[0028] It should be noted that, in practical applications, the CaO content in the calcium carbide slag is ≥92wt%; the blast furnace slag is S95 grade granulated blast furnace slag powder with CaO (calcium oxide) content ≥42wt%, SiO2 (silicon dioxide) content ≥27wt%, and Al2O3 (alumina) content ≥25wt%; and the fly ash is Class F grade 1 fly ash with SiO2 content ≥50wt% and Al2O3 content ≥31wt%.

[0029] S2.1: Acquire the current and vibration data of the mixer at the start of slurry mixing.

[0030] The process of mixing dry materials with water after mixing is called slurry mixing. This application will collect and analyze the operating data of the mixer during the slurry mixing process to judge the mixing state of the materials inside the slurry. After identifying that the materials have reached a uniform mixing state, the mixing will be stopped in time, thereby providing a basis for judging the mixing state under different raw material ratios, while avoiding interference from changes in raw material ratios and blade attachments on the judgment results.

[0031] During the slurry mixing process, this application uses a current sensor to collect the load output current data of the mixer in real time to reflect the load changes of the mixer during the mixing process; at the same time, a vibration sensor is used to collect the vibration data of the mixer during operation in real time.

[0032] The current and vibration data of the mixer were collected simultaneously at the start of slurry mixing. The data acquisition frequency was 500Hz and the duration of each data acquisition cycle was 5 seconds.

[0033] It should be noted that in actual application scenarios, since the material cannot be mixed evenly in the first few cycles of mixing, this embodiment takes the i-th cycle after the Nth cycle (the value ranges from 1 to 7, and is 5 in this embodiment) as an example for analysis. At the same time, in the first N cycles, the stop evaluation step is skipped and the mixing operation continues.

[0034] Preferably, for ease of understanding and description, in this embodiment, based on the current data and vibration data collected within the i-th cycle, the current sequence and vibration sequence for the i-th cycle are constructed respectively according to the temporal order of data collection. To eliminate the influence of dimensions between data, maximum value normalization is performed on all data. The specific process is a well-known technique and will not be elaborated in this embodiment. In actual application scenarios, implementers can choose other existing normalization methods.

[0035] In addition, after the material preparation is completed, performance tests are conducted on the material. Materials that meet the requirements for use in road base courses in terms of flowability, unconfined compressive strength, and heavy metal leaching performance are recorded as qualified materials. The slurry mixing process during the preparation of qualified materials is recorded as a qualified mixing process. Data from a total of T (100 in this embodiment) qualified mixing processes are obtained. The specific qualified materials selected are up to the implementer in actual application, and no special restrictions are imposed on this in this embodiment.

[0036] It should be noted that under the same process system conditions, even if the weight ratio of different raw materials changes, when the slurry reaches a uniform mixing state, the overall operating state of the mixer usually exhibits relatively stable and similar change characteristics. Therefore, the qualified mixing process collected in this embodiment can cover the ratio conditions corresponding to all embodiments of this application, providing a reference for subsequent determination of whether the mixing state of the slurry has reached a uniform mixing state.

[0037] Since the raw vibration data contains a large amount of high-frequency mechanical clutter, a moving average filter is applied to the collected vibration data before subsequent calculations to reduce its dimensionality to low-frequency trend data that characterizes the vibration intensity. In practical applications, implementers can use other existing filtering methods to preprocess the collected data. The specific filtering process is existing technology and will not be described in detail in this embodiment.

[0038] S2.2: Analyze the discrete characteristics and abrupt changes of current and vibration data in each cycle during the stirring process to obtain the dispersion unevenness of each cycle.

[0039] During slurry mixing, the current and vibration data of the mixer change to varying degrees with the changes in the slurry flow state. When the materials inside the slurry are not fully dispersed, the distribution of the raw materials is uneven, resulting in significant changes in local flow resistance, which in turn leads to noticeable fluctuations in the mixer's current and vibration data. As the materials inside the slurry gradually disperse and become more uniform, the overall flow state of the slurry gradually stabilizes, and the fluctuations in the collected mixer's current and vibration data also tend to stabilize. Therefore, we can first analyze the changing trends of the collected data within each cycle to preliminarily analyze the possibility of uniform material mixing within each cycle.

[0040] Let's take the i-th cycle in the current slurry mixing process as an example for analysis.

[0041] Specifically, in this embodiment, the dispersion of the current sequence and the dispersion of the vibration sequence in the i-th period are calculated respectively, and the sum of the dispersion of the current sequence and the dispersion of the vibration sequence is denoted as the first discrete value of the i-th period. The first discrete value can reflect the fluctuation of the mixer's operating state in the i-th period. The larger the value, the greater the fluctuation of the electric mixer's state, and the greater the possibility that the overall flow resistance characteristics of the slurry have not reached a stable state. The method of calculating the dispersion is not limited to the coefficient of variation, root mean square deviation, and variance; in this embodiment, variance is used for calculation.

[0042] Furthermore, in the initial stage of mixing when the materials are not fully dispersed and uniform, agglomerates of materials such as waste incineration bottom ash will continuously break up under shearing action. The moment of breaking often produces instantaneous abrupt changes, resulting in a large number of abrupt changes in current and vibration data. As the mixing process continues, the agglomerates gradually disappear, which also leads to a gradual decrease in the abrupt changes in the collected data.

[0043] Taking the current sequence of the i-th period as an example, the number of all current abrupt changes in the current sequence is obtained through an abrupt change detection algorithm, and the ratio of the number of current abrupt changes to the total number of current data in the i-th period is calculated. Correspondingly, the ratio of the number of vibration abrupt changes to the total number of vibration data in the i-th period is calculated. The average of the two ratios is recorded as the average abrupt change percentage of the i-th period. The abrupt change detection algorithm is not limited to the PELT algorithm, Pettitt algorithm, and MK algorithm; this embodiment uses the PELT algorithm.

[0044] The average percentage of mutations can reflect the frequency of instantaneous disturbances during the stirring process in the i-th cycle; the larger the value, the more mutations occur during the stirring process, and the greater the possibility that the materials inside the slurry are not fully dispersed.

[0045] Constructing the dispersion unevenness of the i-th period : In the formula, This is the first discrete value in the i-th period; represents the average percentage of mutations in the i-th period; norm() is a normalization function. To avoid the problem that the parameter is too large and other parameters have a weak influence, it is not limited to the tanh function, sigmoid function, or exponential normalization function. In this embodiment, it is the exponential normalization function.

[0046] Among them, the dispersion unevenness can reflect the degree of disorder in the dispersion state of materials inside the slurry in the i-th cycle; the smaller the value, the more stable the mixing state of the mixer in the i-th cycle, and the lower the frequency of abrupt changes. This indicates that the distribution of various materials inside the slurry is more uniform and the dispersion state between materials has tended to be stable.

[0047] The dispersion unevenness is reflected by the first discrete value to reflect the degree of fluctuation in the mixer's operating state in the i-th cycle; the average proportion of mutations is reflected to reflect the frequency of mutations in the mixing process in the i-th cycle; finally, by summing the first discrete value and the average proportion of mutations, the overall fluctuation characteristics and instantaneous disturbance characteristics in the cycle can be reflected simultaneously, so as to make a more comprehensive assessment of the material dispersion state in the slurry mixing process.

[0048] It should be noted that both sides of the equation are dimensionless numerical values. Dimensional analysis: Since the current and vibration data have already been normalized, the values ​​on the right side of the equation are dimensionless. , All values ​​are numerical and dimensionless; therefore, the final result is... It is also a dimensionless value.

[0049] S2.3: By utilizing the changing trend of dispersion unevenness in different periods, combined with the similarity between current data and vibration data within the period and the fluctuation of similarity, the stirring fluctuation index of each period is obtained.

[0050] Furthermore, considering that during the mixing process, some fine particles will form wet clumps upon contact with water and adhere to the mixing blades or shaft, even if the material inside the slurry is basically evenly dispersed, the material adhering to the blades will still change the mixing resistance as the blades rotate, causing fluctuations in the mixer's current and vibration data. Therefore, if analysis is based solely on data changes from a single cycle, such structural disturbances could easily be misinterpreted as incomplete mixing, potentially leading to excessively long mixing times. Further analysis is therefore necessary.

[0051] In this embodiment, we will still take the i-th cycle as an example for analysis.

[0052] If the materials in the slurry are basically mixed evenly by the i-th cycle, then even if the adhering substances cause fluctuations, the fluctuations in the collected data will be relatively consistent in the i-th cycle and the preceding cycles.

[0053] Specifically, in this embodiment, the i-th period and the preceding T consecutive periods are taken as the detection segment of the i-th period, where T is greater than or equal to 1. Therefore, there are at least two data acquisition periods within the detection segment. In this embodiment, T is set to 5.

[0054] All dispersion unevenness within the detection segment is used as input to a straight line fitting algorithm for straight line fitting. The absolute value of the slope of the fitted line is recorded as the first slope of the i-th period. The first slope reflects the changing trend of dispersion unevenness between the i-th period and its adjacent periods. The smaller the value, the smaller the change in dispersion unevenness between the i-th period and the previous few adjacent periods, and the more similar the fluctuations between periods, indicating that the stirring process is more likely to have stabilized.

[0055] Furthermore, when the materials inside the slurry are not fully dispersed, the distribution of materials in the mixing area is highly random, and the local resistance changes are unstable. This also leads to highly randomness in the collected current and vibration data, which do not have correlation characteristics.

[0056] Once the materials are uniformly mixed and the overall flow of the slurry stabilizes, the changes in resistance generated during stirring will be more concentratedly reflected in the overall load changes, thus causing a certain correlation between the current and vibration data in terms of their trends. Furthermore, if the materials are basically mixed, but fluctuations in the current and vibration data are caused by adhering substances, the correlation between the current and vibration data will be further enhanced.

[0057] However, since the influence of the adhering material on the stirring resistance needs to be transmitted through the equipment structure before it manifests as a vibration response, there is usually a certain time lag between the current change and the vibration change. The DTW (Dynamic Time Warping) similarity between the current sequence and the vibration sequence in the i-th period is calculated and denoted as the DTW similarity of the i-th period, to reflect the degree of trend correlation between the current data and the vibration data under the allowable time offset. DTW similarity is a known technique. In this embodiment, the DTW similarity can be measured by the reciprocal of the DTW distance between the two sequences. To avoid the denominator being zero during the reciprocal calculation, a very small positive number is added to the denominator; in this embodiment, the value is 0.001. The calculation of the DTW distance is existing technology and will not be described in detail in this embodiment.

[0058] The DTW similarity of each cycle within the detection section is calculated in the same way, and the dispersion between all DTW similarities is denoted as the second discrete value of the i-th cycle. The second discrete value reflects the stability of the matching relationship between current data and vibration data within the detection section; the larger the value, the greater the difference in the correspondence between current data and vibration data during different cycles, the stronger the randomness of load changes during stirring, and the greater the possibility that the material is not sufficiently dispersed.

[0059] Therefore, in this embodiment, the stirring fluctuation index for the i-th period is constructed. : In the formula, The first slope of the i-th period; The second discrete value in the i-th period; Let be the DTW similarity for the i-th period; The parameter is a coefficient for parameter tuning. To avoid the denominator being 0, the value range is (0.05, 0.1). The value has little impact on the calculation result and can be ignored. In this embodiment, 0.08 is used.

[0060] Among them, the stirring fluctuation index can comprehensively reflect the overall fluctuation of the stirring state in the i-th cycle; the larger the value, the more obvious the uneven distribution of materials inside the slurry in the i-th cycle, and the more obvious the stirring resistance changes between different cycles, the greater the possibility that the stirring process has not entered a stable state.

[0061] The stirring fluctuation index reflects the uniformity of material dispersion in the i-th cycle through dispersion unevenness; it reflects the changing trend of stirring state between multiple adjacent cycles through the first slope; it reflects the stability of the relationship between current data and vibration data through the second discrete value; it reflects the matching relationship between current data and vibration data in the i-th cycle through DTW similarity; and finally, by constructing the stirring fluctuation index, the true mixing state of the slurry in the i-th cycle is comprehensively analyzed.

[0062] It should be noted that both sides of the equation are dimensionless numerical values, representing primitive physical quantities without physical units. Dimensional analysis: The right side of the equation... Numerical value; In this embodiment, the slope of the fitted straight line is used to characterize the slope. Used to characterize DTW similarity The values ​​used to characterize the dispersion of DTW similarity are all numerical; therefore, the final calculated value is... It is also a numerical value, without physical dimensions.

[0063] S2.4: Construct a qualified value range based on the stirring fluctuation index of the qualified material during the stirring process, and then determine the time when the stirring stops.

[0064] Furthermore, although raw materials such as waste incineration bottom ash, carbide slag, blast furnace slag, and fly ash differ in density and particle size, and their movement states during mixing will also vary, the mixing state of the mixer will be relatively stable once the materials within the slurry are fully dispersed and uniformly mixed. In addition, under the same process system conditions, even with slight variations in the weight ratio of raw materials, the current and vibration characteristics of the mixer will still exhibit similar stable patterns when the slurry reaches a fully mixed state. Therefore, by combining the data characteristics collected during historical mixing processes with good performance, it is possible to determine whether a stable mixing state has been reached in the current cycle, and accordingly assess whether mixing can be stopped.

[0065] Since qualified materials usually reach a uniform mixing state in the last cycle of the stirring process, the stirring fluctuation index of the last cycle of each qualified stirring process prepared with the same raw material ratio as the current stirring is calculated according to the stirring fluctuation index of the i-th cycle, and used as the stirring fluctuation index of each qualified stirring process.

[0066] A qualified value range is constructed based on the maximum and minimum values ​​of all stirring fluctuation indices for all qualified stirring processes.

[0067] Taking the i-th cycle as an example, during the current slurry mixing process, we iterate forward through M (range 1-3, 2 in this embodiment) consecutive cycles, with the i-th cycle as the last cycle. For ease of understanding, in this embodiment, the i-th cycle and the previous M cycles are both recorded as the termination evaluation cycle of the current slurry mixing process, and the mixing fluctuation index of the termination evaluation cycle is obtained.

[0068] If the stirring fluctuation index of M+1 interruption evaluation cycles is within the qualified range during this slurry mixing process, then the operating state of the mixer is relatively stable in multiple consecutive cycles, and the current mixing state of the slurry is consistent with the stable state in the qualified process. It can be determined that the overall flow resistance characteristics of the slurry have become stable in the i-th cycle, and the slurry is mixed evenly. At this time, the last moment of the i-th cycle is taken as the stirring interruption moment, and stirring is stopped to avoid unnecessary energy consumption and possible local segregation caused by continuing stirring. Otherwise, if the stirring fluctuation index of the M+1 suspension evaluation cycles is not all within the qualified range, then the current stirring process still has some fluctuations, and the material inside the slurry has not been fully dispersed. At this time, the suspension condition is not met, and stirring needs to continue, and the i+1th cycle is entered. Then, the suspension evaluation is carried out for each subsequent cycle in the above manner.

[0069] Thus, by constructing a stirring fluctuation index and a qualified value range, and combining it with a continuous evaluation method across multiple adjacent periods, the true mixing state during the slurry stirring process can be determined. This avoids problems such as uneven material dispersion due to insufficient stirring time, or increased energy consumption or even local segregation due to excessive stirring time. Furthermore, the stirring evaluation method proposed in this embodiment can adapt to differences in stirring state caused by different raw material ratios, raw material densities, and particle size variations, thereby improving the stability of the slurry stirring effect and increasing the robustness of the preparation of controllable low-strength materials.

[0070] S3: After the slurry is mixed, it is poured into a mold to form a shape, and then demolded and cured to obtain a controllable low-strength material for road base.

[0071] The slurry was poured into a mold to form a shape. After one day, it was demolded and placed in a constant temperature and humidity chamber at 20°C and 95% relative humidity for curing. The curing times were 7 days and 28 days, respectively, to prepare a controllable low-strength material for road base.

[0072] Furthermore, this application tests the flowability of the controllable low-strength material according to ASTM D6103. Specifically, a steel cylinder with a diameter of 75 mm and a depth of 150 mm is placed stably on a glass plate wiped with a damp towel. The cylinder is then filled with a well-mixed controllable low-strength material slurry. The cylinder is then lifted vertically upwards in one go, and the diameter of the cake-like substance formed on the glass plate after the slurry collapses is measured with a steel ruler in both the maximum diameter direction and its perpendicular direction. The average of the two diameters is taken as the flowability. Unconfined compressive strength tests are conducted after 7 days and 28 days of curing, with a loading rate of 1 mm / min. After the 28-day unconfined compressive strength test, a broken piece from the center of the specimen is taken for heavy metal leaching tests according to the "Solid Waste Leaching Toxicity Leaching Method - Acetic Acid Buffer Solution Method" (HJT3002007).

[0073] Example 2: The solid raw materials described in this example are specifically composed of the following components by weight: 100 parts of waste incineration bottom ash; 3 parts of calcium carbide slag; 15 parts of blast furnace slag; and 10 parts of fly ash.

[0074] The difference between this embodiment and Embodiment 1 is that the amount of calcium carbide slag added is 3 parts. The preparation method, flowability test, unconfined compressive strength test, and heavy metal leaching test of the controllable low-strength material for road base are the same as in Embodiment 1, and will not be repeated here.

[0075] Example 3: The solid raw materials described in this example are specifically composed of the following components by weight: 100 parts of waste incineration bottom ash; 5 parts of calcium carbide slag; 15 parts of blast furnace slag; and 10 parts of fly ash.

[0076] The difference between this embodiment and Embodiment 1 is that the amount of calcium carbide slag added is 5 parts. The preparation method, flowability test, unconfined compressive strength test, and heavy metal leaching test of the controllable low-strength material for road base are the same as in Embodiment 1, and will not be repeated here.

[0077] Example 4: The solid raw materials described in this example are specifically composed of the following components by weight: 100 parts of waste incineration bottom ash; 5 parts of calcium carbide slag; 10 parts of blast furnace slag; and 10 parts of fly ash.

[0078] The difference between this embodiment and Embodiment 1 is that the amounts of calcium carbide slag and blast furnace slag added are 5 parts and 10 parts, respectively. The preparation method, flowability test, unconfined compressive strength test, and heavy metal leaching test of the controllable low-strength material for road base are the same as in Embodiment 1, and will not be repeated here.

[0079] Example 5: The solid raw materials described in this example are specifically composed of the following components by weight: 100 parts of waste incineration bottom ash; 5 parts of calcium carbide slag; 20 parts of blast furnace slag; and 10 parts of fly ash.

[0080] The difference between this embodiment and Embodiment 1 is that the amounts of calcium carbide slag and blast furnace slag added are 5 parts and 20 parts, respectively. The preparation method, flowability test, unconfined compressive strength test, and heavy metal leaching test of the controllable low-strength material for road base are the same as in Embodiment 1, and will not be repeated here.

[0081] Example 6: The solid raw materials described in this example are specifically composed of the following components by weight: 100 parts of waste incineration bottom ash; 5 parts of calcium carbide slag; 15 parts of blast furnace slag; and 5 parts of fly ash.

[0082] The difference between this embodiment and Embodiment 1 is that the amount of calcium carbide slag and fly ash added is 5 parts each. The preparation method, flowability test, unconfined compressive strength test, and heavy metal leaching test of the controllable low-strength material for road base are the same as in Embodiment 1, and will not be repeated here.

[0083] Example 7: The solid raw materials described in this example are specifically composed of the following components by weight: 100 parts of waste incineration bottom ash; 5 parts of calcium carbide slag; 15 parts of blast furnace slag; and 15 parts of fly ash.

[0084] The difference between this embodiment and Embodiment 1 is that the amounts of calcium carbide slag and fly ash added are 5 parts and 15 parts, respectively. The preparation method, flowability test, unconfined compressive strength test, and heavy metal leaching test of the controllable low-strength material for road base are the same as in Embodiment 1, and will not be repeated here.

[0085] Furthermore, this application conducted flowability and unconfined compressive strength tests on the controllable low-strength materials for road base prepared in Examples 1 to 7. The specific test results are shown in Table 1: Table 1. Flowability and Unconfined Compressive Strength of Controlled Low-Strength Materials for Road Base Course As shown in Table 1, the fluidity of the materials in all embodiments exceeds 220 mm, exhibiting high fluidity, excellent self-leveling and self-compacting properties. When applied to the base and subbase of highway pavements, no manual vibration and compaction are required, making construction convenient.

[0086] Comparing Examples 1-3, it can be seen that increasing the amount of calcium carbide slag helps to create a high-alkali, high-calcium environment, stimulating the reactivity of blast furnace slag and fly ash, promoting the alkali-activated reaction, and thus improving the unconfined compressive strength. Comparing Examples 3-5, it can be seen that increasing the amount of blast furnace slag significantly improves the material's fluidity and unconfined compressive strength. The good physical filling effect and high cementitious reactivity of blast furnace slag are conducive to further filling pores and improving the overall density. When the amount of blast furnace slag added is increased to 20 parts, the 7-day unconfined compressive strength reaches 5.27 MPa, meeting the strength requirements of the base and subbase layers of expressways and first-class highways in the "Technical Specifications for Construction of Highway Pavement Base Layers" (JTG / T F20-2015). Comparing Examples 3 and Examples 6-7, it can be seen that increasing the amount of fly ash enhances the material's fluidity by utilizing the ball-bearing effect of fly ash, while also filling internal pores, thereby improving the material's unconfined compressive strength. With an addition of 5 parts of calcium carbide slag, by adjusting the addition amounts of blast furnace slag and fly ash, the controllable low-strength material prepared by this invention can meet the strength requirements of the base and subbase layers of highway pavements of various grades, thus expanding the application scenarios of waste incineration bottom ash resource utilization.

[0087] In this application, heavy metal leaching tests were conducted on the controllable low-strength materials for road base prepared in Examples 1-7. The specific test results are shown in Table 2. Table 2 Heavy metal leaching concentrations in controlled low-strength materials used in road base courses As shown in Table 2, the heavy metal leaching concentrations of the materials in all embodiments are lower than the limits in the "Standard for Pollution Control of Hazardous Waste Landfill" (GB 18598-2019), indicating that the prepared road base material with controllable low strength effectively solidifies the heavy metals in the bottom ash of waste incineration and will not cause environmental pollution when applied to the road base.

[0088] Based on the same inventive concept as the above method, this application embodiment also provides a controllable low-strength material for road base course, which is prepared by any of the steps of the method for preparing a controllable low-strength material for road base course as described in any one of the claims, wherein the mass of water accounts for 30% of the mass of all solid raw materials in the raw materials for preparing the controllable low-strength material.

[0089] It is understood that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this specification. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.

[0090] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0091] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Any equivalent structural or procedural transformations made based on the description and drawings of this application, or direct or indirect applications in other related technical fields, are similarly included within the protection scope of this application.

Claims

1. A method for preparing a controllable low-strength material for road base courses, characterized in that, Includes the following steps: Waste incineration bottom ash, carbide slag, blast furnace slag, fly ash and water are selected as raw materials for the preparation of controllable low strength materials for road base. Waste incineration bottom ash, carbide slag, blast furnace slag and fly ash are mixed to obtain dry material mixture, and then water is added and mixed to obtain slurry. At the start of slurry mixing, current and vibration data of the mixer are acquired. The discrete characteristics and abrupt changes of the current and vibration data in each cycle during the mixing process are analyzed to obtain the dispersion unevenness of each cycle. The formula for obtaining the dispersion unevenness of each cycle is as follows: In the formula, Let be the dispersion unevenness of the i-th period; Let be the first discrete value of the i-th period, where the first discrete value is the sum of the discreteness of the current data and the discreteness of the vibration data within the i-th period; is the average percentage of mutations in the i-th cycle; norm() is the normalization function; where, the ratio of the number of mutation points in the current data to the total number of current data and the ratio of the number of mutation points in the vibration data to the total number of vibration data in the i-th cycle are calculated, and the average of the two ratios is taken as the average percentage of mutations in the i-th cycle. By utilizing the variation trend of dispersion unevenness in different periods, combined with the similarity between current data and vibration data within the period and the fluctuation of the similarity, the stirring fluctuation index for each period is obtained. The formula for obtaining the stirring fluctuation index for each period is as follows: In the formula, Let be the stirring fluctuation index for the i-th period. Let be the dispersion unevenness in the i-th period. The first slope of the i-th period; The second discrete value in the i-th period; Let be the DTW similarity of the i-th cycle; The parameters are set as follows: The i-th cycle and several consecutive cycles preceding it are considered as the detection segment of the i-th cycle. A straight line is fitted to all the dispersion inhomogeneities within the detection segment, and the absolute value of the slope of the fitted line is taken as the first slope of the i-th cycle. The DTW similarity between the current data and vibration data within the i-th cycle is statistically analyzed. The dispersion of the DTW similarity corresponding to each cycle within the detection segment of the i-th cycle is calculated and taken as the second discrete value of the i-th cycle. A qualified value range is constructed based on the stirring fluctuation index corresponding to the qualified material during the stirring process, thereby determining the stirring termination time. After the slurry is mixed, it is poured into a mold to form a shape, and then demolded and cured to obtain a controllable low-strength material for road base.

2. The method for preparing a controllable low-strength material for road base courses as described in claim 1, characterized in that, Calculate the stirring fluctuation index of the last cycle in each qualified stirring process. Use the minimum and maximum values ​​of all stirring fluctuation indices calculated from all qualified stirring processes to form the qualified value range. The qualified stirring process is the slurry stirring process corresponding to the pre-selected qualified material.

3. The method for preparing a controllable low-strength material for road base courses as described in claim 1, characterized in that, The determination of when to stop stirring is as follows: if the stirring fluctuation index of the current cycle and several consecutive cycles before it is within the qualified range, then stirring is stopped; otherwise, stirring continues.

4. The method for preparing a controllable low-strength material for road base courses as described in claim 1, characterized in that, After demolding, place the product in a constant temperature and humidity chamber at 20℃ and 95% relative humidity for curing.

5. A controllable low-strength material for road base courses, prepared by the steps of the method for preparing a controllable low-strength material for road base courses according to any one of claims 1-4, characterized in that, In the raw materials for preparing the controllable low-strength material, the mass of water accounts for 30% of the total mass of all solid raw materials.

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