A method for preparing a waste fly ash asphalt mortar separation specimen and a method for characterizing the migration behavior and distribution characteristics of waste fly ash in asphalt binder

Abstract

The present invention discloses a method for preparing a waste fly ash asphalt mortar segregation specimen and a method for characterizing the migration behavior and distribution characteristics of waste fly ash in asphalt binder. Since the engineering environment is simulated, the prepared waste fly ash asphalt mortar segregation specimen is more in line with the actual engineering situation; the active migration area and specific position of the waste fly ash are accurately located through the mass change value Δi, and the active area specimen and the general active area specimen are obtained; according to the spatial distribution of the waste fly ash inside the active area specimen and the general active area specimen, the area proportion of the waste fly ash in the vertical direction and the horizontal direction are obtained respectively; the vertical segregation index V of the waste fly ash asphalt mortar and the horizontal segregation index L of the waste fly ash asphalt mortar are proposed; more accurate characterization results of the migration law and distribution characteristics of the waste fly ash are obtained with smaller errors, which provides a good basis and guarantee for the subsequent research, application and promotion of waste fly ash in asphalt materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of road materials, and in particular relates to a method for preparing a garbage fly ash asphalt mortar segregation specimen and a method for characterizing the migration behavior and distribution characteristics of garbage fly ash in asphalt binder. Background Art

[0002] Since the concept of sustainable development was proposed, related topics such as resource utilization and green development have been raised one after another. Among them, the feasibility of using waste incineration fly ash in asphalt road materials has been verified, and the modification effect of waste incineration fly ash on asphalt materials has been widely recognized.

[0003] According to the existing specification "Polymer Modified Asphalt Segregation Test Method" (SH-T0740-2003), the existing method for preparing fly ash asphalt mortar specimens and the method for characterizing the storage stability of fly ash in asphalt mortar are: inject SBR, SBS polymer modified asphalt or fly ash asphalt mortar specimens into a sample tube under specified conditions, put it in an oven at 163±5℃, let it stand vertically for 48 hours, take it out of the oven, put it in a refrigerator and let it stand for 4 hours, divide the sample into three equal sections, and conduct softening point tests on the samples of the upper and lower sections at the same time, calculate the difference, and measure the softening point difference to determine the degree of segregation of the modified asphalt. At the same time, the degree of segregation also represents the storage stability of fly ash in asphalt mortar; when it is confirmed that the current fly ash can be stably stored in the asphalt mortar, the asphalt mortar with fly ash will be put into actual engineering.

[0004] However, the above stability and segregation determination and analysis process, as well as the fly ash-containing asphalt mortar prepared based on it, are prone to premature performance degradation of asphalt roads when put into actual projects. After investigation, the researchers found that this was due to a large deviation between the predicted performance of the fly ash asphalt mortar and the actual performance in engineering applications. Therefore, they concluded that the above test specimens were not suitable for actual engineering conditions, and the characterization method could not accurately reflect the segregation characteristics of the fly ash asphalt mortar stored for a long time under high temperature and actual application conditions. The predictions and instructions for actual applications were significantly different from the actual situation.

[0005] Based on this, it is urgent to propose a more advanced, complete and scientific method for preparing fly ash asphalt mortar segregation specimens and a characterization method for the migration behavior and distribution characteristics of fly ash in asphalt mortar, so as to improve its predictive accuracy and precision in actual application and improve engineering quality. Summary of the Invention

[0006] In order to solve the problem that the existing fly ash asphalt mortar specimens are not sufficiently suitable for the actual project and the characterization method thereof cannot accurately reflect the segregation characteristics of fly ash asphalt mortar stored for a long time in a high-temperature environment, the present invention provides a method for preparing fly ash asphalt mortar segregation specimens, and a method for characterizing the migration behavior and distribution characteristics of fly ash in asphalt binder. The specimens are more suitable for the actual project, and the characterization method thereof can provide a basis for the performance degradation of fly ash asphalt mortar stored for a long time in a high-temperature environment, and also provide a basis for improving the storage stability.

[0007] The present invention is achieved through the following technical solutions:

[0008] A method for preparing a waste fly ash asphalt mortar segregation specimen comprises the following steps:

[0009] S1. Select a certain mass of fly ash asphalt mortar, wherein the fly ash asphalt mortar is made of base asphalt and domestic waste fly ash; the base asphalt used is 70# base asphalt, or 90# base asphalt, etc. The meaning of 70# base asphalt is: 70# asphalt, 70 is its grade, which means its needle penetration is between 60-80 (0.1mm), and the grade is determined by the needle penetration; the meaning of 90# base asphalt is: 90# asphalt, 90 is its grade, which means its needle penetration is between 80-100; in previous research papers, some researchers used test materials with a ratio of fly ash to base asphalt of 0.3, 0.6, 0.9, and 12 for research. The amount of fly ash used in actual experiments is prepared according to the needs of the research;

[0010] S2. Place the fly ash asphalt mortar prepared in step S1 in a constant temperature oven at 135°C for 1.5 hours until it is completely melted and passes through a 0.3 mm sieve. Pour the mortar into a clean temporary container and stir it manually with a glass rod for 1 minute. Pour the mortar into a prepared glass beaker to a depth of 5 mm from the rim, and seal the beaker with tin foil.

[0011] S3. Adjust the temperature of the constant temperature oven to 163°C ± 5°C in advance, and adjust the built-in tray of the oven to a horizontal position. Place the fly ash asphalt mortar from step S2 on the tray and keep it in the constant temperature oven for 48 hours before taking it out.

[0012] S4. Immediately place the fly ash asphalt mortar in step S3 into a sealed container, inject liquid nitrogen into the container and keep it warm for 15 minutes, then take it out and place it in a low-temperature environment of -10°C and continue to keep it warm for not less than 4 hours to obtain a fly ash asphalt mortar specimen.

[0013] Furthermore, in step S2, the glass beaker prepared in advance is a 125 mm×Φ90 mm non-tempered glass beaker without a guide port, and the inner wall of the beaker is evenly coated with a dimethylsiloxane solution with a thickness of 1 mm.

[0014] A method for characterizing the migration behavior and distribution characteristics of landfill fly ash in asphalt binder comprises the following steps:

[0015] S1. Prepare a unit volume test piece of unsegregated fly ash asphalt mortar to obtain the unit volume mass N of the unsegregated fly ash asphalt mortar;

[0016] S2. vertically cutting the fly ash asphalt mortar specimen obtained by the above preparation method to obtain several segregated steady-state specimens;

[0017] S3. Weigh and obtain the weight of several segregated steady-state specimens, and obtain the unit volume mass of the fly ash asphalt mortar in the segregated steady-state specimens as M. i ;

[0018] S4, according to the calculation formula: Δ i =M i -N, and obtain the mass change value of fly ash asphalt mortar in the segregated steady-state specimen Δ i , and according to Δ i The numerical value of determines the segregation steady-state specimen with active fly ash migration;

[0019] S5. Based on the two-dimensional image of the spatial distribution of fly ash in asphalt mortar, obtain the area ratio C of fly ash in asphalt mortar in the two-dimensional image of the upper surface of the segregated steady-state specimen. ij , the calculation formula is: C ij =D ij / S ij × 100%, where D ij It represents the surface area of ​​fly ash on the segregated steady-state specimen, S ij represents the surface area of ​​the segregated steady-state specimen, i represents the segregated steady-state specimen with a fixed length of i, and j represents the segregated steady-state specimen with a fixed height of j;

[0020] S6. Divide the upper surface of the segregated steady-state specimen into regions and obtain the area ratio E of the fly ash in the divided regions. ikj , the calculation formula is: E ikj =F ikj / R ikj × 100%, where F represents the area of ​​the garbage fly ash in the divided area, R represents the area of ​​the divided area, and k represents the kth divided area;

[0021] S7, according to the calculation formula: V = Max {C ij}-Min{C ij} and calculation formula: The vertical segregation index V of fly ash asphalt mortar and the horizontal segregation index L of fly ash asphalt mortar are proposed, among which, Indicates the area proportion of garbage fly ash in the divided area E ikj The average value of .

[0022] Furthermore, the step S4 also includes calculating the mass change value Δ in a number of segregated steady-state specimens. i The minimum and maximum values ​​of, and the mass change value Δ i The average of the minimum and maximum values ​​of the segregated steady-state specimens is determined as the active area specimen, and the segregated steady-state specimen closest to the average value is determined as the general active area specimen; in step S5, the area ratio C of the fly ash in the asphalt mortar in the two-dimensional image of the upper surface of the active area specimen and the general active area specimen is obtained. ij ; In the step S6, the active area specimen and the general active area specimen are divided into regions on the upper surface.

[0023] Furthermore, in step S7,

[0024] It also includes obtaining the average value Q of the percentage of fly ash area on the upper surface of the specimen in the general active area, and the calculation formula is: Q = (C i1 +……+C ij ) / j;

[0025] Among them, C ij represents the area proportion of garbage fly ash in the general active area specimen, i represents the segregated steady-state specimen with a fixed length of i, and j represents the general active area specimen with a fixed height of j.

[0026] Furthermore, the step S7 also includes: comparing the vertical segregation index V of the fly ash asphalt mortar with the average value Q of the fly ash area ratio on the upper surface of the general active area specimen to determine the vertical segregation degree of the fly ash asphalt mortar.

[0027] Furthermore, the step S7 further includes: determining the horizontal segregation degree of the fly ash asphalt mortar according to the numerical value of the horizontal segregation index L of the fly ash asphalt mortar.

[0028] Furthermore, the step S1 further includes:

[0029] S1-1. Select 70# matrix asphalt and domestic waste fly ash in a mass ratio of 100:30;

[0030] S1-2. Place the 70# matrix asphalt and domestic waste fly ash from step S1-1 in a 135°C constant temperature oven for 1.5 hours until completely melted and passed through a 0.3 mm sieve. Pour the sieved waste fly ash asphalt mortar into a clean temporary container and stir manually with a glass rod for 1 minute.

[0031] S1-3. Slowly fill the asphalt mortar in the temporary container into a clean 15mm×Φ90mm standard container. Use a metal plate to scrape the surface of the asphalt mortar along the flat surface of the standard container cup and wipe off the excess asphalt on the surface of the standard container.

[0032] S1-4. Use a high-precision electronic balance to weigh the mass of fly ash asphalt mortar in the standard container.

[0033] Furthermore, the step S2 further includes:

[0034] S2-1. Remove the frozen fly ash asphalt mortar specimen, apply two layers of transparent tape to the side surface to mark the cutting position, place it horizontally and fix it on the platform of a water jet cutter, and use the water jet cutter to remove any uneven parts on the top and bottom to obtain a segregated steady-state specimen with smooth upper and lower surfaces.

[0035] S2-2. Use a water jet cutting machine to cut the segregation specimen at different lengths on the side to obtain several segregation steady-state specimens of equal length.

[0036] Furthermore, the step S3 further includes:

[0037] S3-1. Prepare 2Y temporary containers and Y clean 15mm×Φ90mm standard containers in advance;

[0038] S3-2. Place several segregated steady-state specimens into Y temporary containers and heat at 135°C for 1.5 hours until completely melted. Pass the melted segregated steady-state specimens through a 0.3 mm sieve and pour them into another Y temporary glass containers. Stir with a glass rod for 1 minute, then slowly pour them into Y standard containers and smooth the surface with a metal plate.

[0039] S3-3. Use a high-precision electronic balance to weigh the unit volume mass M of fly ash asphalt mortar in Y standard containers. i .

[0040] The beneficial effects of the present invention are:

[0041] (1) Since the fly ash asphalt separation specimens were prepared using a beaker instead of the sample tube specified in the specification, the separation specimens prepared using the beaker had a larger diameter and would not restrict the lateral movement of the fly ash in the asphalt. The separation specimens prepared using the small aluminum tube had a smaller diameter, which restricted the lateral movement of the fly ash. The separation specimens prepared using the beaker took the lateral movement of the fly ash into consideration. Therefore, the prepared fly ash asphalt mortar specimens were more in line with the actual project situation.

[0042] (2) First, the active migration area and specific location of fly ash are accurately located through the mass change value Δi, and the active area specimens and general active area specimens are obtained; secondly, according to the spatial distribution of fly ash in the active area specimens and general active area specimens, the area proportions of fly ash in the vertical and horizontal directions are obtained; then, the vertical segregation index V of fly ash asphalt mortar and the horizontal segregation index L of fly ash asphalt mortar are proposed; finally, the vertical and horizontal segregation degrees of fly ash asphalt mortar are determined, and a more accurate characterization result of the migration law and distribution characteristics of fly ash is obtained with smaller error, which provides a good basis and guarantee for the subsequent research, application and promotion of fly ash in asphalt materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a flow chart of a method for preparing a waste fly ash asphalt mortar separation specimen according to the present invention;

[0044] Figure 2 This is a flow chart of a method for characterizing the migration behavior and distribution characteristics of fly ash in asphalt binder according to the present invention;

[0045] Figure 3 Schematic diagram of steps S2 to S4 in a method for characterizing the migration behavior and distribution characteristics of fly ash in asphalt binder according to the present invention;

[0046] Figure 4 This is a schematic diagram of a method for scanning fly ash asphalt mortar using Micro-CT scanning in the present invention;

[0047] Figure 5 It is a schematic diagram of the regional division on the upper surface of the segregated steady-state specimen according to the present invention. DETAILED DESCRIPTION

[0048] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0049] Reference Figure 1First, a method for preparing a segregation specimen of fly ash asphalt mortar is used to obtain two segregation steady-state specimens, including the following steps:

[0050] S1. Select 70# matrix asphalt and domestic waste fly ash with a binder mass ratio of 100:30. The meaning of 70# matrix asphalt is: 70# asphalt, 70 is its grade, which means its needle penetration is between 60-80 (0.1mm). The grade is determined by the needle penetration.

[0051] S2. Prepare two clean 125mm×Φ90mm non-tempered non-guided glass beakers in advance, and evenly coat the inner wall of the beaker with a 1mm thick dimethylsiloxane solution. The dimethylsiloxane solution acts as a lubricant, making it easy to remove the specimen from the beaker. Place the two portions of 70# matrix asphalt and domestic waste fly ash in step S1 in a 135°C constant temperature oven for 1.5 hours until completely melted and passed through a 0.3mm sieve. Pour them into a clean temporary container, stir manually with a glass rod for 1 minute, and finally pour them into the two prepared glass beakers to 5mm from the cup mouth, and seal the beaker with tin foil;

[0052] S3. According to the conditions in the "Test Method for Segregation of Polymer-Modified Asphalt" (SH-T0740-2003), the temperature of the constant temperature oven was adjusted to 163°C ± 5°C in advance, and the built-in tray of the oven was adjusted to a horizontal position. The fly ash asphalt mortar in the two glass beakers in step S2 was placed on the tray and kept in the constant temperature oven for 48 hours before being removed;

[0053] S4. Immediately place the fly ash asphalt mortar in the two glass beakers in step S3 into a sealed container, inject liquid nitrogen into the container and keep it warm for 15 minutes, then take it out and place it in a low-temperature environment of -10°C and continue to keep it warm for not less than 4 hours to obtain two fly ash asphalt mortar specimens, or two segregated steady-state specimens; one of them is named segregated steady-state specimen No. 1, and the other is named segregated steady-state specimen No. 2, and the liquid nitrogen instantaneous freezing technology is used in this step.

[0054] Reference Figure 2-Figure 5 , a method for characterizing the migration behavior and distribution characteristics of fly ash in asphalt binder, specifically as follows:

[0055] S1. Preparing a unit volume test piece of unsegregated fly ash asphalt mortar, comprising the following steps:

[0056] (1) Select 70# matrix asphalt and domestic waste fly ash with a binder mass ratio of 100:30, test and verify the technical indicators of each raw material in accordance with the requirements of the specification, and select 70# matrix asphalt and domestic waste fly ash that meet the requirements of the specification;

[0057] (2) Place the fly ash asphalt mortar in a constant temperature oven at 135°C for 1.5 hours until it is completely melted and passes through a 0.3 mm sieve. Pour the sieved fly ash asphalt mortar into a clean temporary container and stir it manually with a glass rod for 1 minute.

[0058] (3) Slowly fill the asphalt mortar in the temporary container into a clean 15mm×Φ90mm standard container, use a metal plate to scrape the surface of the asphalt mortar along the plane of the cup of the standard container, and wipe off the excess asphalt on the surface of the standard container. The reason for not using a 20mm×Φ90mm standard container is that the separation specimen may cause slight mass loss during the cutting process, so the size of the standard container needs to be smaller than the size of the separation specimen to be cut;

[0059] (4) The mass of the fly ash asphalt mortar in the standard container is weighed using a high-precision electronic balance, which is 99.78 g. This mass is used as the unit volume mass N of the unsegregated fly ash asphalt mortar; that is, the current unit volume mass N of the unsegregated fly ash asphalt mortar is 99.78 g.

[0060] S2. Cutting the two fly ash asphalt mortar specimens obtained by the above-mentioned preparation method, and obtaining a number of segregated steady-state specimens by using a water jet precision cutting technique, including the following steps:

[0061] (1) Take the frozen segregation steady-state specimen No. 1 out of the beaker, stick two layers of transparent tape on the side surface to mark the cutting position, then place it horizontally and fix it on the platform of the water jet cutting machine. Use the water jet cutting machine to cut off the 10 mm uneven parts on the top and bottom of the segregation steady-state specimen No. 1 to obtain a segregation steady-state specimen No. 1 with a flat upper and lower surface and a length of 100 mm;

[0062] (2) Using a water jet cutter, cut the segregation specimen at 20 mm, 40 mm, 60 mm, and 80 mm on its side to obtain five segregation steady-state specimens with a length of 20 mm. These specimens are named as segregation steady-state specimen A1, segregation steady-state specimen A2, segregation steady-state specimen A3, segregation steady-state specimen A4, and segregation steady-state specimen A5 from top to bottom, respectively.

[0063] In the above, the segregation steady-state specimen A1, the segregation steady-state specimen A2, the segregation steady-state specimen A3, the segregation steady-state specimen A4 and the segregation steady-state specimen A5 are collectively referred to as segregation steady-state specimens in different regions;

[0064] Among them, the water jet abrasive is corundum, the initial punching water pressure is 170-220MPa, and the normal cutting water pressure is 320MPa.

[0065] S3. Weigh and obtain the weight of several segregated steady-state specimens, and obtain the unit volume mass of the fly ash asphalt mortar in the segregated steady-state specimens as M. i ;

[0066] S4, according to the calculation formula: Δ i =M i -N, and obtain the mass change value of fly ash asphalt mortar in the segregated steady-state specimen Δ i , and according to Δ i The numerical value of is used to determine the segregated steady-state specimen where the fly ash migration is active, that is, to accurately locate the area where the fly ash migration is active and the specific location where the fly ash migration is active, which specifically includes the following steps:

[0067] (1) Prepare 10 temporary containers and 5 clean 15mm×Φ90mm standard containers in advance;

[0068] (2) Separately place the segregated steady-state specimen A1, segregated steady-state specimen A2, segregated steady-state specimen A3, segregated steady-state specimen A4 and segregated steady-state specimen A5 into five temporary containers and heat them at 135°C for 1.5 hours until they are completely melted; pass the melted segregated steady-state specimen A1, segregated steady-state specimen A2, segregated steady-state specimen A3, segregated steady-state specimen A4 and segregated steady-state specimen A5 through a 0.3 mm sieve and inject them into the other five temporary glass containers respectively. After stirring with a glass rod for 1 minute, slowly inject them into the five standard containers respectively and use a metal plate to smooth the surface;

[0069] (3) Using a high-precision electronic balance, the unit volume mass of the fly ash asphalt mortar in five standard containers was measured to be M1 = 89.75 g, M2 = 93.63 g, M3 = 99.36 g, M4 = 104.87 g, and M5 = 110.43 g.

[0070] (4) Using mass change value Δ i The calculation formula is: Δ i =M i -N; calculate the mass change value Δ of each segregated steady-state specimen i , where M represents the mass per unit volume of fly ash asphalt mortar in the segregated steady-state specimen (g, accurate to two decimal places); N represents the mass per unit volume of fly ash asphalt mortar in the specimen without segregation treatment (g); i represents the length of the i-th 20 mm segregated steady-state specimen A i ;

[0071] After calculation, the mass changes of A1-A5 are: Δ1=M1-N=89.75-99.78=-10.03g, Δ2=-6.15g, Δ3=0.42g, Δ4=5.11g, Δ5=10.65g, and the relevant results are shown in Table 1;

[0072] Table 1 Segregation steady-state specimen unit volume mass and mass change value

[0073]

[0074] It can be seen that Δ1 and Δ5 are the minimum and maximum values ​​respectively, so the segregated steady-state specimens A1 and A5 are used as two specimens in the active area of ​​fly ash migration; at the same time, the average values ​​of Δ1 and Δ5 are calculated to be 0.31g. It can be found that Δ3 of segregated specimen A3 is closest to the average value, so A3 will be used as the specimen in the general active area of ​​fly ash migration.

[0075] (5) Cut the segregated steady-state specimen No. 2 using the same cutting method as in step S2 to obtain segregated steady-state specimen A6-A 10 , the same is 5 sections of 20mm long segregation steady-state specimens, and according to the Δ obtained in the segregation steady-state specimen No. 1 i Results show that in the segregation steady-state specimen A6-A 10 Select A6 and A 10 as active area specimens, and A8 as general active area specimens;

[0076] (6) The two active area specimens A6 and A 10 , and a two-layer transparent tape was pasted on the side of a general active area specimen A8, and then it was placed horizontally and fixed on the water jet cutting machine platform for cutting. The water jet cutting machine was used to make vertical cuts at 5mm, 10mm, and 15mm of the length of each specimen side to obtain 2×4 sections of 5mm high garbage fly ash asphalt mortar migration active area specimens and 1×4 sections of 5mm high migration general active area specimens; among them, the specimens cut from the segregation specimen A6 were named segregation specimens A and B from top to bottom. 61 , Separation specimen A 62 , Separation specimen A 63 , Separation specimen A 64 , by separating specimen A 10 The cut specimens are named as separation specimens A and B from top to bottom. 101 , Separation specimen A 102 , Separation specimen A 103 , Separation specimen A 104 The specimens cut from the isolated specimen A8 are named as isolated specimen A from top to bottom. 81 , Separation specimen A 82 Separation specimen A 83 , Separation specimen A 84 .

[0077] S5. Based on the two-dimensional image of the spatial distribution of fly ash in asphalt mortar, obtain the area ratio C of fly ash in asphalt mortar in the two-dimensional image of the upper surface of the segregated steady-state specimen. ij , refer to Figure 4 , specifically:

[0078] Micro-CT was used to scan the segregated steady-state specimen A 61 -A 64 , Segregation steady-state specimen A 81 -A 84 , Separation specimen A 101 -A 104 Then, the digital model of the fly ash asphalt mortar was reconstructed through the supporting software, and the two-dimensional image of the upper surface of the fly ash asphalt mortar segregation specimen was restored; that is, the spatial distribution of fly ash in the asphalt mortar was obtained. Among them, the Micro-CT scanning method was spiral tomography, the test resolution was selected as 3072×3072 pixels, and the fault interval was ≤0.1mm.

[0079] S7, according to the calculation formula: V = Max {C ij}-Min{C ij} and calculation formula: The vertical segregation index V of fly ash asphalt mortar and the horizontal segregation index L of fly ash asphalt mortar are proposed, specifically:

[0080] (1) Using ImageJ-Pro, calculate the area ratio C of fly ash in asphalt mortar in the two-dimensional image of the upper surface of the segregated steady-state specimen. ij , the calculation formula is: C ij =D ij / S ij ×100%;

[0081] Among them, D ij It represents the surface area of ​​fly ash powder on the segregated steady-state specimen, S ij Indicates the surface area of ​​the segregated steady-state specimen, the area of ​​the fly ash on the surface of the segregated steady-state specimen D ij The area F of the fly ash fine powder in the divided area is calculated using ImageJ-Pro software, where i represents the i-th segregated steady-state specimen with a length of 20 mm, and j represents the j-th segregated steady-state specimen with a height of 5 mm;

[0082] In addition, the surface area S of the segregated steady-state specimen is ij This can be calculated using the formula for calculating the area of ​​a circle.

[0083] Get the segregation steady-state specimen A 61 -A 64 , Segregation steady-state specimen A 81 -A84 , Segregation steady-state specimen A 101 -A 104 The area ratio of medium-sized garbage fly ash in asphalt mortar is C 61 -C 64 、C 81 -C 84 、C 101 -C 104 , and the relevant results are shown in Table 2;

[0084] Table 2 Calculation results of the area ratio of fly ash in asphalt binder

[0085]

[0086] (2) Obtain the average value Q of the percentage of fly ash area on the upper surface of the specimen in the general active area, and the calculation formula is: Q = (C i1 +……+C ij ) / j;

[0087] Among them, C ij represents the area proportion of garbage fly ash in the general active area specimen, i represents the i-th segregated steady-state specimen with a length of 20 mm, and j represents the j-th segregated steady-state specimen with a height of 5 mm or the j-th general active area specimen with a height of 5 mm.

[0088] Specimen A in the four general active migration areas mentioned above 81 -A 84 The average value Q of the percentage of fly ash area on the upper surface is calculated as follows:

[0089] Q=(C 81 +C 82 +C 83 +C 84 ) / 4=(27.88%+28.10%+28.33%+30.31%) / 4=28.66%

[0090] (3) Calculate the vertical segregation index V of fly ash asphalt mortar. The calculation formula is:

[0091] V=Max{C ij}-Min{C ij =C 104 -C 61 =40.49%-19.71%=20.78%

[0092] (4) Compare the vertical segregation index V of the fly ash asphalt mortar with the average value Q of the fly ash area ratio on the upper surface of the specimen in the general active area, as shown in Table 3;

[0093] Table 3 Evaluation criteria for vertical migration behavior of fly ash fine powder

[0094] Q value range Vertical segregation evaluation criteria Q<V serious <h2 style=";text-align:left;direction:ltr">0.75Q <V<1Q <h2 style=";text-align:left;direction:ltr"> More serious 0.5Q <V<0.75Q Moderate <h2 style=";text-align:left;direction:ltr">0.25Q <V<0.5Q <h2 style=";text-align:left;direction:ltr"> generally 0<V<0.25Q Mild

[0095] When V is greater than 1 times of Q value, the fly ash asphalt mortar will produce serious vertical segregation;

[0096] When V is 0.75 to 1 times of Q, fly ash asphalt mortar will produce serious vertical segregation;

[0097] When V is 0.5 to 0.75 times the Q value, the fly ash asphalt mortar produces moderate vertical segregation;

[0098] When V is 0 to 0.5 times the Q value, the fly ash asphalt mortar will produce general vertical segregation;

[0099] When V is 0 to 0.25 times the Q value, the fly ash asphalt mortar produces slight vertical segregation.

[0100] However, Q×0.5=28.66%×0.5=14.33%<V=20.78%<Q×0.75=28.66×0.75=21.50%. Therefore, it is believed that the fly ash asphalt mortar in this embodiment underwent moderate vertical segregation after the segregation treatment.

[0101] (5) Separate steady-state specimens A6, A8 and A 10 The upper surface is divided into four areas, which serve as the horizontal / lateral migration characterization areas of the fly ash fine powder in the segregated steady-state specimen. The specific division method is as follows:

[0102] Reference Figure 5 , four concentric circles with diameters of 22 mm, 44 mm, 66 mm, and 88 mm were drawn from the center of the upper surface of the segregation steady-state specimen, which was divided into four areas, named area ①, area ②, area ③, and area ④. The specific description of the shape of each area is as follows:

[0103] The shape of area ① is a circle with a diameter of 22 mm;

[0104] Area ② is a ring with an outer diameter of 44 mm and an inner diameter of 22 mm;

[0105] The shape of area ③ is a ring with an outer diameter of 66mm and an inner diameter of 44mm;

[0106] The shape of area ④ is a ring with an outer diameter of 66mm and an inner diameter of 88mm.

[0107] (6) Using ImageJ-Pro software, the divided areas ①-④ were processed respectively to obtain the area proportion E of the garbage fly ash in each divided area. ikj, the calculation formula is E ikj =F ikj / R ikj ×100%;

[0108] Where F represents the area of ​​fly ash fine powder in the divided area, R represents the area of ​​the divided area, and k represents the kth divided area;

[0109] Therefore, the segregation steady-state specimen A needs to be calculated. 61 -A 64 , Segregation steady-state specimen A 81 -A 84 , Segregation steady-state specimen A 101 -A 104 The area proportion of fly ash in the ①-④ region on the upper surface of the , the calculation results are shown in Table 4.

[0110] Table 4 Calculation results of the area proportion of garbage fly ash in different areas

[0111] Specimen number <![CDATA[A 61 ]]> <![CDATA[A 62 ]]> <![CDATA[A 63 ]]> <![CDATA[A 64 ]]> <![CDATA[A 81 ]]> <![CDATA[A 82 ]]> <![CDATA[A 83 ]]> <![CDATA[A 84 ]]> <![CDATA[A 101 ]]> <![CDATA[A 102 ]]> <![CDATA[A 103 ]]> <![CDATA[A 104 ]]> ①(％) 18.62 22.21 23.33 25.68 27.89 29.10 28.51 32.11 38.11 40.33 39.11 41.81 ②(％) 19.98 21.09 23.51 25.01 28.44 28.44 28.90 31.01 38.60 39.81 39.54 40.31 ③(％) 18.21 23.11 22.98 25.55 26.99 28.55 27.90 29.66 37.99 39.77 40.19 40.11 ④(％) 19.33 22.91 23.22 25.91 27.54 27.45 26.69 30.12 35.29 38.69 39.92 41.23

[0112] (7) Calculate the horizontal segregation index L of fly ash asphalt mortar using the following formula:

[0113]

[0114] in, Indicates the area proportion of garbage fly ash in the divided area E ikj The average value of

[0115] The above segregation steady-state specimen A 61 -A 64 , Segregation steady-state specimen A 81 -A 84 , Segregation steady-state specimen A 101 -A 104 The calculation results of the horizontal segregation index L are shown in Table 5.

[0116] Table 5 Horizontal segregation index L of fly ash asphalt mortar in different specimens

[0117] Specimen number <![CDATA[A 61 ]]> <![CDATA[A 62 ]]> <![CDATA[A 63 ]]> <![CDATA[A 64 ]]> <![CDATA[A 81 ]]> <![CDATA[A 82 ]]> <![CDATA[A 83 ]]> <![CDATA[A 84 ]]> <![CDATA[A 101 ]]> <![CDATA[A 102 ]]> <![CDATA[A 103 ]]> <![CDATA[A 104 ]]> L 0.73 0.79 0.19 0.33 0.53 0.59 0.84 0.94 1.29 0.60 0.41 0.69

[0118] (8) The horizontal migration or horizontal segregation behavior of fly ash asphalt mortar is judged according to the value of the horizontal segregation index L of fly ash asphalt mortar, as described below:

[0119] When the horizontal segregation index L of fly ash asphalt mortar is less than 1, the fly ash asphalt mortar does not undergo obvious horizontal segregation behavior;

[0120] When the horizontal segregation index L of fly ash asphalt mortar is greater than 1 and less than 2, the fly ash asphalt mortar has undergone a general degree of horizontal segregation behavior;

[0121] When the horizontal segregation index L of fly ash asphalt mortar is greater than 2, the fly ash asphalt mortar undergoes serious horizontal segregation behavior;

[0122] It can be seen from this that the horizontal segregation index L of the fly ash asphalt mortar in this embodiment is less than 1, which proves that the garbage fly ash asphalt mortar does not undergo obvious horizontal segregation behavior after the segregation treatment.

[0123] According to the results in Table 1, the active migration area of ​​fly ash asphalt mortar can be accurately located by the degree of mass change. When the mass change value is positive, it indicates that fly ash powder tends to gather in this area, and the larger the value, the more fly ash powder gathers in this area, and the smaller the value, the less fly ash powder gathers in this area. When the mass change value is negative, it indicates that fly ash tends to leave this area, and the larger the value, the less fly ash powder leaves this area, and the smaller the value, the more fly ash powder leaves this area. Therefore, regardless of whether the mass change value is positive or negative, the larger its absolute value means that the migration behavior of fly ash powder in this area is more active.

[0124] According to the calculation results in Table 2 and Table 3, the fly ash asphalt mortar produced moderate vertical segregation, which means that corresponding measures need to be taken to restore the uniformity of the fly ash asphalt mortar after it is transported to the construction site.

[0125] According to the results in Tables 4 and 5, there is no obvious fluctuation in the horizontal distribution of the area proportion of fly ash, indicating that the segregation test has little effect on the horizontal distribution uniformity of fly ash in asphalt mortar.

[0126] In addition, in summary: Segregation steady-state specimen No. 1 is used to determine the active area and general active area of ​​garbage fly ash in asphalt mortar; segregation steady-state specimen No. 2 is used to study the horizontal migration behavior and vertical migration behavior of garbage fly ash in asphalt mortar; at the same time, garbage fly ash powder and garbage fly ash are the same thing, and garbage fly ash powder is a refined expression.

[0127] In summary, the present invention provides an effective, sensitive and highly accurate method for characterizing the migration behavior and distribution characteristics of landfill fly ash in asphalt binder. The method uses Micro-CT scanning reconstruction technology to restore the spatial distribution of landfill fly ash inside the asphalt mortar, and uses ImageJ Pro software to quantitatively analyze the migration behavior of landfill fly ash inside the asphalt mortar, which helps to clarify the migration behavior and distribution characteristics of landfill fly ash in asphalt mortar, and provides a good basis and guarantee for the subsequent research, application and promotion of landfill fly ash in asphalt materials.

[0128] The above-described embodiment merely represents one embodiment of the present invention. While the description is relatively specific and detailed, it should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the spirit of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a fly ash asphalt mortar separation specimen, characterized in that: The following steps are involved: S1. Select a certain mass of fly ash asphalt mortar; S2. Place the fly ash asphalt mortar prepared in step S1 in a constant temperature oven at 135°C for 1.5 hours until it is completely melted and passes through a 0.3 mm sieve. Pour the mortar into a clean temporary container and stir it manually with a glass rod for 1 minute. Pour the mortar into a prepared glass beaker to a depth of 5 mm from the rim, and seal the beaker with tin foil. S3. Adjust the temperature of the constant temperature oven to 163°C ± 5°C in advance, and adjust the built-in tray of the oven to a horizontal position. Place the fly ash asphalt mortar from step S2 on the tray and keep it in the constant temperature oven for 48 hours before taking it out. S4. Immediately place the fly ash asphalt mortar in step S3 into a sealed container, inject liquid nitrogen into the container and keep it warm for 15 minutes, then take it out and place it in a low-temperature environment of -10°C and continue to keep it warm for not less than 4 hours to obtain a fly ash asphalt mortar separation specimen.

2. The method for preparing a fly ash asphalt mortar separation specimen according to claim 1, characterized in that: In step S2, the glass beaker prepared in advance is a 125 mm×Φ90 mm non-tempered glass beaker without a guide port, and the inner wall of the beaker is evenly coated with a dimethylsiloxane solution with a thickness of 1 mm.

3. A method for characterizing the migration behavior and distribution characteristics of fly ash in asphalt binder, characterized in that: The following steps are involved: S1. Prepare a unit volume test piece of unsegregated fly ash asphalt mortar to obtain the unit volume mass N of the unsegregated fly ash asphalt mortar; S2. vertically cutting the waste fly ash asphalt mortar segregation specimen as claimed in claim 1 or 2 to obtain a plurality of segregation steady-state specimens; S3. Weigh and obtain the weight of several segregated steady-state specimens, and obtain the unit volume mass of the fly ash asphalt mortar in the segregated steady-state specimens as M. i ; S4, according to the calculation formula: Δ i =M i -N, and obtain the mass change value of fly ash asphalt mortar in the segregated steady-state specimen Δ i , and according to Δ i The numerical value of determines the segregation steady-state specimen with active fly ash migration; S5. Based on the two-dimensional image of the spatial distribution of fly ash in asphalt mortar, obtain the area ratio C of fly ash in asphalt mortar in the two-dimensional image of the upper surface of the segregated steady-state specimen in the active area of ​​fly ash migration. ij , the calculation formula is: C ij =D ij / S ij × 100%, where D ij It represents the surface area of ​​fly ash on the segregated steady-state specimen, S ij represents the surface area of ​​the segregated steady-state specimen, i represents the segregated steady-state specimen with a fixed length of i, and j represents the segregated steady-state specimen with a fixed height of j; S6. Divide the upper surface of the segregated steady-state specimen from the active migration area of ​​the fly ash to obtain the area ratio E of the fly ash in the divided area. ikj , the calculation formula is: E ikj =F ikj / R ikj × 100%, where F represents the area of ​​the garbage fly ash in the divided area, R represents the area of ​​the divided area, and k represents the kth divided area; S7, according to the calculation formula: V = Max {C ij }-Min{C ij } and calculation formula: Obtain the vertical segregation index V of the garbage fly ash asphalt mortar and the horizontal segregation index L of the garbage fly ash asphalt mortar, wherein, Indicates the area proportion of garbage fly ash in the divided area E ikj The average value of .

4. The method for characterizing the migration behavior and distribution characteristics of fly ash in asphalt binder according to claim 3 is characterized in that: The step S4 also includes calculating the mass change value Δ in a number of segregated steady-state specimens. i The minimum and maximum values ​​of, and the mass change value Δ i The average of the minimum and maximum values ​​of the segregated steady-state specimens is determined as the active area specimen, and the segregated steady-state specimen closest to the average value is determined as the general active area specimen; in step S5, the area ratio C of the fly ash in the asphalt mortar in the two-dimensional image of the upper surface of the active area specimen and the general active area specimen is obtained. ij ; In the step S6, the active area specimen and the general active area specimen are divided into regions on the upper surface.

5. The method for characterizing the migration behavior and distribution characteristics of fly ash in asphalt binder according to claim 4 is characterized in that: In the step S7, It also includes obtaining the average value Q of the percentage of fly ash area on the upper surface of the specimen in the general active area, and the calculation formula is: Q = (C i1 +……+C ij ) / j; Among them, C ij represents the area proportion of garbage fly ash in the general active area specimen, i represents the segregated steady-state specimen with a fixed length of i, and j represents the general active area specimen with a fixed height of j.

6. The method for characterizing the migration behavior and distribution characteristics of fly ash in asphalt binder according to claim 5, characterized in that: Said step S7 further includes: comparing the vertical segregation index V of the fly ash asphalt mortar with the average value Q of the fly ash area ratio on the upper surface of the general active area specimen to determine the vertical segregation degree of the fly ash asphalt mortar.

7. The method for characterizing the migration behavior and distribution characteristics of fly ash in asphalt binder according to claim 3, characterized in that: Said step S7 further includes: determining the horizontal segregation degree of the fly ash asphalt mortar according to the numerical value of the horizontal segregation index L of the fly ash asphalt mortar.

8. The method for characterizing the migration behavior and distribution characteristics of fly ash in asphalt binder according to claim 3, characterized in that: The step S1 further includes: S1-1. Select 70# matrix asphalt and domestic waste fly ash in a mass ratio of 100:30; S1-2. Place the 70# matrix asphalt and domestic waste fly ash from step S1-1 in a 135°C constant temperature oven for 1.5 hours until completely melted and passed through a 0.3 mm sieve. Pour the sieved waste fly ash asphalt mortar into a clean temporary container and stir manually with a glass rod for 1 minute. S1-3. Slowly fill the asphalt mortar in the temporary container into a clean 15mm×Φ90mm standard container. Use a metal plate to scrape the surface of the asphalt mortar along the flat surface of the standard container cup and wipe off the excess asphalt on the surface of the standard container. S1-4. Use a high-precision electronic balance to weigh the mass of fly ash asphalt mortar in the standard container.

9. The method for characterizing the migration behavior and distribution characteristics of fly ash in asphalt binder according to claim 3, characterized in that: The step S2 further includes: S2-1. Remove the frozen fly ash asphalt mortar specimen, apply two layers of transparent tape to the side surface to mark the cutting position, place it horizontally and fix it on the platform of a water jet cutter, and use the water jet cutter to remove any uneven parts on the top and bottom to obtain a segregated steady-state specimen with smooth upper and lower surfaces. S2-2. Use a water jet cutting machine to cut the segregation specimen at different lengths on the side to obtain several segregation steady-state specimens of equal length.

10. The method for characterizing the migration behavior and distribution characteristics of fly ash in asphalt binder according to claim 3, characterized in that: The step S3 further includes: S3-1. Prepare 2Y temporary containers and Y clean 15mm×Φ90mm standard containers in advance; S3-2. Place several segregated steady-state specimens into Y temporary containers and heat at 135°C for 1.5 hours until completely melted. Pass the melted segregated steady-state specimens through a 0.3 mm sieve and pour them into another Y temporary glass containers. Stir with a glass rod for 1 minute, then slowly pour them into Y standard containers and smooth the surface with a metal plate. S3-3. Use a high-precision electronic balance to weigh the unit volume mass M of fly ash asphalt mortar in Y standard containers. i .

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