A method for evaluating the water erosion resistance of drainage asphalt mixtures

Abstract

This invention belongs to the field of road engineering technology, specifically relating to a method for evaluating the water erosion resistance of drainage asphalt mixtures. The method includes the following steps: taking a drainage asphalt mixture specimen to be tested; immersing the specimen in water for ultrasonic treatment; the water temperature is 59.5–60.5℃, and the ultrasonic treatment frequency is 45–55kHz; drying the specimen after ultrasonic treatment to a constant temperature; and evaluating the water erosion resistance level based on changes in specimen mass, Kentenberg scattering loss, and bond strength before and after ultrasonic treatment. The evaluation method proposed in this invention provides practical guidance for the reasonable evaluation of water erosion resistance, is easy to operate, and is a highly feasible indoor testing method. The results obtained provide valuable guidance for evaluating the water erosion resistance of drainage asphalt mixtures.

Description

Technical Field

[0001] This invention belongs to the field of road engineering technology, and specifically relates to a method for evaluating the water erosion resistance of drainage asphalt mixtures. Background Technology

[0002] Drainage asphalt mixture refers to an open-graded asphalt mixture with a porosity of approximately 20% after compaction, allowing surface water to drain through its internal voids. Drainage asphalt pavement is a typical skeletal porous structure with numerous interconnected voids forming a comprehensive drainage network. Rainwater can seep through this network to the waterproofing layer and then flow along the road's cross slope to the curb drainage ditches. However, in actual use, some water remains within the structure. High-speed vehicles cause air pressure generated between the tires and the road surface, which is then dissipated through the voids in the drainage pavement. Simultaneously, the airflow causes free water to oscillate, eroding the asphalt film and leading to defects such as particle shedding and potholes. This severely impairs pavement performance, significantly affecting road smoothness, driving safety and comfort, and also impacting vehicle energy consumption, tire wear, and transportation efficiency.

[0003] A proper evaluation of the durability of drainage asphalt mixtures under water erosion conditions is fundamental to expanding the application of this technology. Currently, the immersion Marshall test and freeze-thaw splitting test are commonly used for water damage assessment, but these methods deviate significantly from the destructive principle of water flow oscillation and erosion. Therefore, there is no effective method for evaluating the water erosion resistance of drainage asphalt mixtures. Summary of the Invention

[0004] To address the shortcomings in this field, the present invention aims to provide a method for accurately evaluating the water erosion resistance of drainage asphalt mixtures.

[0005] Specifically, the present invention provides the following technical solution:

[0006] A method for evaluating the water erosion resistance of drainage asphalt mixtures includes the following steps:

[0007] 1) Take a sample of the drainage asphalt mixture to be tested and designate it as Specimen A;

[0008] 2) Determine the mass, Kentenberg scattering loss, and bond strength of specimen A;

[0009] 3) Place specimen A in water for ultrasonic treatment; the water temperature is 59.5-60.5℃, and the ultrasonic treatment frequency is 45-55kHz.

[0010] 4) After ultrasonic treatment for a certain period of time, specimen A is dried to a constant temperature and recorded as specimen B;

[0011] 5) Determine the mass, Kentucky scattering loss, and bond strength of specimen B.

[0012] Calculate the percentage decrease in mass of specimen B relative to the mass of specimen A, X1;

[0013] Calculate the percentage increase in Kentucky scattering loss of specimen B relative to Kentucky scattering loss of specimen A, multiplied by 2.

[0014] Calculate the percentage decrease in bond strength of specimen B relative to the bond strength of specimen A, multiplied by 3.

[0015] The smaller the values ​​of X1, X2, and X3, the better the water erosion resistance of the drainage asphalt mixture.

[0016] Preferably, in the above-mentioned method for evaluating the water erosion resistance of drainage asphalt mixtures, in step 1), the drainage asphalt mixture specimen to be tested is a Marshall specimen prepared from drainage asphalt mixture or a specimen obtained by core drilling and cutting from drainage asphalt pavement. According to the present invention, the specimen in step 1) can be obtained by core sampling from the pavement and then cutting it into specimens of a specified height, or it can be formed in an indoor laboratory. The laboratory forming method follows the Marshall specimen forming method in T0702-2011 of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering JTG E20-2011". Preferably, the dimensions of the Marshall specimen meet the following requirements: diameter 101.6 ± 0.2 mm, height 63.5 ± 1.3 mm.

[0017] Preferably, in the above-mentioned evaluation method for the water erosion resistance of drainage asphalt mixture, in step 3), during the ultrasonic treatment, the water level should be at least 25 mm above the upper surface of specimen A.

[0018] Preferably, in the above-mentioned method for evaluating the water erosion resistance of drainage asphalt mixtures, in step 4), the ultrasonic treatment time is 19-21 hours, 39-41 hours, or 59-61 hours. This invention has found that the mass, Kentau scattering loss, and bond strength measurements of the specimen after 19-21 hours of ultrasonic treatment are similar to the results after the specimen has undergone approximately 7200 mm of total rainfall in actual use. Similarly, the results after 39-41 hours and 59-61 hours of ultrasonic treatment are similar to the results after approximately 18000 mm and 25000 mm of total rainfall in actual use, respectively. Therefore, the evaluation method proposed in this invention provides practical guidance for the reasonable evaluation of water erosion resistance.

[0019] Preferably, in the above-mentioned method for evaluating the water erosion resistance of drainage asphalt mixtures, in step 4), the ultrasonically treated specimen A is dried to a constant temperature below 40°C. This invention has found that excessively high drying temperatures will soften the specimen, thereby affecting the results of subsequent tests on scattering and bond strength.

[0020] Preferably, in the above-mentioned method for evaluating the water erosion resistance of drainage asphalt mixtures, in step 5), the percentage decrease in mass of specimen B relative to the mass of specimen A, X1, is calculated according to the following formula:

[0021] X1 = 100% × (m0 - m1) / m0;

[0022] Where m0 is the mass of specimen A; and m1 is the mass of specimen B.

[0023] Preferably, in the above-mentioned evaluation method for the water erosion resistance of drainage asphalt mixtures, the Kentucky scattering loss ΔS of the specimen is calculated according to the following formula:

[0024] △S=100%×(m3–m4) / m3;

[0025] Where: m3 is the mass of the specimen before the Kentucky scattering test;

[0026] m4 is the maximum remaining mass of the specimen after the Kentucky scattering test.

[0027] According to the present invention, the specimen is placed in a Los Angeles abrasion tester to conduct the Kentucky fly test; preferably, in the Kentucky fly test, the Los Angeles abrasion tester rotates 300 revolutions at a speed of 30-33 r / min, and only a single specimen can be tested at a time, without the addition of steel balls. More preferably, the Kentucky fly test is conducted according to the requirements of the Highway Engineering Asphalt and Asphalt Mixture Test Procedure JTGE20-2011, with the Los Angeles abrasion tester rotating 300 revolutions at a speed of 30 r / min.

[0028] Preferably, in the above-mentioned evaluation method for the water erosion resistance of drainage asphalt mixtures, the bond strength of the specimen is calculated as follows: The upper and lower surfaces of the specimen are bonded to two steel plate pull heads with a diameter of 101.6 mm using strong epoxy adhesive. After curing at room temperature for 4 days (until the epoxy adhesive reaches its strength), it is cured at a constant temperature of 60℃ for 3.5–4.5 hours. The upper and lower steel plate pull heads of the cured specimen are then fixed to a tensile testing machine and stretched at a speed of 4–6 mm / min until the specimen completely breaks. The experiment is then completed, and the maximum tensile force F and the cross-sectional area A at the fracture point are recorded. The bond strength σ of the specimen is calculated using the formula σ = F / A. (If the fracture occurs at the epoxy adhesive, the specimen is not properly bonded, and the data is invalid.)

[0029] Preferably, in the above-mentioned method for evaluating the water erosion resistance of drainage asphalt mixtures, in step 4), the ultrasonic treatment time is 40 hours, and the water erosion resistance level is determined based on the obtained X1, X2, and X3 as follows:

[0030]

[0031] This invention discovers that when the ultrasonic treatment time is 40 hours, the grades of drainage asphalt mixtures with different water erosion resistance can be clearly distinguished according to the water erosion resistance rating criteria given in the table above. The result provides valuable guidance for those skilled in the art to evaluate the water erosion resistance of drainage asphalt mixtures.

[0032] The beneficial effects achieved by this invention are as follows:

[0033] The evaluation method proposed in this invention provides practical guidance for the reasonable evaluation of water erosion resistance. It uses conventional performance testing instruments and the specimens are easy to obtain. Cores can be taken on-site and cut into specimens of specified sizes, or specimens can be formed indoors. It is convenient to operate and is a highly feasible indoor testing method. The evaluation results provide valuable guidance for the evaluation of the water erosion resistance of drainage asphalt mixtures. Attached Figure Description

[0034] Figure 1 The results show the mass loss of the specimen in Example 1 after ultrasonic treatment for different durations.

[0035] Figure 2 The results show the Kentucky scattering loss of the specimens in Example 1 after ultrasonic treatment for different durations.

[0036] Figure 3 The results show the bonding strength of the specimens in Example 1 after ultrasonic treatment for different durations.

[0037] Figure 4 The results show the mass loss of specimens from Scheme 1 and Scheme 2 after ultrasonic treatment for different durations in a practical application example.

[0038] Figure 5 The results show the Kentucky scattering loss of specimens from Scheme 1 and Scheme 2 after ultrasonic treatment for different durations in a practical application example.

[0039] Figure 6 The results show the bonding strength of specimens from Scheme 1 and Scheme 2 after ultrasonic treatment for different durations in a practical application example. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to specific embodiments, but it is not intended to limit the scope of the present invention.

[0041] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the experimental materials and related equipment used in the following examples are commercially available.

[0042] Example 1

[0043] S1: Eight groups of Marshall specimens (Specimen A) of drainage asphalt mixture were prepared in the laboratory. The specific composition was as follows: SBS modified asphalt produced by Lunt Asphalt Plant, with an asphalt-aggregate ratio of 4.8%; HVA high viscosity additive produced by Zhonglu Jiaojian Company, with an addition amount of 8% of the modified asphalt; the aggregate composition was 10-15mm basalt, 5-10mm basalt, 0-3mm limestone, and limestone powder. The PAC13 gradation is shown in Table 1 below.

[0044] Table 1 Gradation Range and Synthetic Gradation

[0045]

[0046] S2: Measure the dry mass of specimen A and take the average value as m0; then take one set to measure the Kentburg scattering loss and take the other set to measure the bond strength.

[0047] in,

[0048] Kentucky scattering loss: The Kentucky scattering test was conducted on specimens using a Los Angeles abrasion tester according to the requirements of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering JTGE20-2011". After the instrument stopped, the largest remaining portion of the specimen was removed and its mass m2 was measured. The Kentucky scattering loss rate of the specimen was calculated according to RR = 100% × (m1 - m2) / m1. Where: m1—specimen mass, g; m2—mass of the specimen after scattering, g;

[0049] Bond strength test: The specimen used to determine the bond strength is bonded to a steel plate pull head with a diameter of 101.6 mm using strong epoxy adhesive. It is cured at room temperature for 4 days until the epoxy adhesive reaches its strength. The specimen is then placed in a curing chamber at 60℃ for 4 hours. After curing, the specimen is removed and the upper and lower pull heads are fixed to a tensile testing machine. Tensioning is performed at a speed of 5 mm / min until the specimen completely breaks. If the breakage occurs at the epoxy adhesive, the specimen is not properly bonded, and the data is invalid. The bond strength is calculated using the formula σ = F / A, where: F—maximum force, N; A—cross-sectional area of ​​the specimen, cm². 2 .

[0050] S3: The remaining 6 groups of specimens were treated with ultrasonic equipment and water rinsing. The water rinsing time was set to 20h, 40h and 60h. Two groups of specimens were treated for each rinsing time. The wave frequency was 50kHz and the water temperature was 60℃±0.5℃.

[0051] S4: Take out the specimen and place it in a 40℃ forced-air drying oven and dry it to constant weight to obtain specimen B. Weigh the dry mass m1.

[0052] S5: Calculate the mass loss X1 of the specimens after water rinsing for 20h, 40h, and 60h using the formula X1 = 100% × (m0 - m1) / m0, and take the average value. Where: m0—dry mass of the specimen before water rinsing treatment, g; m1—mass of the specimen after water rinsing treatment, g; the corresponding calculation results are as follows: Figure 1 As shown; X1(20h) = 0.97%, X1(40h) = 1.49%, X1(60h) = 2.11%;

[0053] After measuring the mass loss of the specimens, one set of specimens each with water rinsing times of 20h, 40h, and 60h were selected to determine the Kentucky scattering loss of the specimens. The results are as follows: Figure 2 As shown; calculate the percentage increase X2 of Kentucky scattering loss of specimen B relative to Kentucky scattering loss of specimen A, X2(20h) = 26.7%, X2(40h) = 58.1%, X2(60h) = 80.2%;

[0054] After measuring the mass loss of the specimens, one set of specimens each with water rinsing times of 20h, 40h, and 60h were selected for bond strength testing. The results are as follows: Figure 3 As shown; calculate the percentage decrease in bond strength of specimen B relative to the bond strength of specimen A, X3, X3(20h) = 17.6%, X3(40h) = 35.3%, X3(60h) = 52.9%;

[0055] S5: The ultrasonic treatment time is 40 hours. The obtained X1(40h) = 1.49%, X2(40h) = 58.1%, X3(40h) = 35.3%. Therefore, the water erosion resistance grade of the drainage asphalt mixture in Example 1 is determined to be level 5.

[0056]

[0057] Practical application examples

[0058] The following two case-related tests were conducted based on on-site road surface core sampling and indoor Marshall comparison.

[0059] (1) Option 1

[0060] The specific composition of the drainage asphalt mixture is as follows: SBS modified asphalt produced by Lunte Asphalt Plant, with an asphalt-aggregate ratio of 4.8%; HVA high-viscosity additive produced by Zhonglu Jiaojian Company, with an addition amount of 8% within the modified asphalt. The aggregate composition consists of 10-15mm basalt, 5-10mm basalt, 0-3mm limestone, and limestone powder, with graded components as shown in Table 2 below.

[0061] Table 2 Grading Range and Synthetic Grading

[0062]

[0063] The initial dispersion loss of the drainage asphalt mixture described in Scheme 1 is 8.8%, and the initial bond strength is 3.1 MPa. Using the drainage asphalt mixture described in Scheme 1 as a pavement material in actual application, samples were taken after approximately 7200 mm, 18000 mm, and 25000 mm of total rainfall to determine the mass loss, dispersion loss, and bond strength. The results are shown in Table 3 below:

[0064] Table 3

[0065]

[0066] Marshall specimens were prepared in the laboratory from the drainage asphalt mixture described in Scheme 1, and processed according to steps S2-S4 of Example 1. Figure 4 The results show the mass loss of the specimens after ultrasonic treatment for different durations. Figure 5 The results of Kentucky scattering loss after the specimens were ultrasonically treated for different durations. Figure 6 The results show the bonding strength of the specimens after ultrasonic treatment for different durations.

[0067] Compare the results in Table 3 with... Figure 4-6 The comparison shows that the results of the mass, Kentau scattering loss and bonding strength of the specimen after ultrasonic treatment for 20 hours, 40 hours and 60 hours are similar to the results of the specimen after being washed by a total rainfall of about 7200mm, 18000mm and 25000mm in actual use.

[0068] (2) Option 2

[0069] The specific composition of the drainage asphalt mixture is as follows: SBS modified asphalt produced by Shell Asphalt Plant, with an asphalt-aggregate ratio of 4.8%; and HVA high-viscosity additive produced by China Road and Bridge Corporation, with an addition amount of 8% within the modified asphalt. The aggregate composition consists of 10-15mm basalt, 5-10mm basalt, 0-3mm limestone, and limestone powder, with graded components as shown in Table 4 below.

[0070] Table 4 Grading Range and Synthetic Grading

[0071]

[0072] The initial dispersion loss of the drainage asphalt mixture described in Scheme 2 is 8.1%, and the initial bond strength is 3.5 MPa. Using the drainage asphalt mixture described in Scheme 2 as a pavement material, samples were taken after approximately 7200 mm, 18000 mm, and 25000 mm of total rainfall to determine the mass loss, dispersion loss, and bond strength. The results are shown in Table 5 below:

[0073] Table 5

[0074]

[0075] Marshall specimens of the drainage asphalt mixture described in Scheme 2 were prepared indoors and processed according to steps S2-S4 of Example 1. Figure 4 The results show the mass loss of the specimens after ultrasonic treatment for different durations. Figure 5 The results of Kentucky scattering loss after the specimens were ultrasonically treated for different durations. Figure 6 The results show the bonding strength of the specimens after ultrasonic treatment for different durations.

[0076] Compare the results in Table 5 with... Figure 4-6 The comparison shows that the results of the mass, Kentau scattering loss and bonding strength of the specimen after ultrasonic treatment for 20 hours, 40 hours and 60 hours are similar to the results of the specimen after being washed by a total rainfall of about 7200mm, 18000mm and 25000mm in actual use.

[0077] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for evaluating the water erosion resistance of drainage asphalt mixtures, characterized in that, Includes the following steps: 1) Take a test specimen of the drainage asphalt mixture to be tested, and denote it as specimen A; 2) Determine the mass, Kentucky scattering loss, and bond strength of specimen A; 3) Place specimen A in water for ultrasonic treatment; the water temperature is 59.5~60.5 ℃, the ultrasonic treatment frequency is 45~55 kHz, and the ultrasonic treatment time is 19~21 hours, 39~41 hours, or 59~61 hours. 4) After ultrasonic treatment for a certain period of time, specimen A is dried at a temperature below 40℃ until it reaches a constant temperature, and is recorded as specimen B; 5) Determine the mass, Kentucky scattering loss, and bond strength of specimen B. Calculate the percentage decrease in mass of specimen B relative to the mass of specimen A, X1; Calculate the percentage increase in Kentucky scattering loss of specimen B relative to Kentucky scattering loss of specimen A, multiplied by 2. Calculate the percentage decrease in bond strength of specimen B relative to the bond strength of specimen A, multiplied by 3. The smaller the values ​​of X1, X2, and X3, the better the water erosion resistance of the drainage asphalt mixture. Based on X1, X2, and X3, the water erosion resistance level is determined as follows: 。 2. The method for evaluating the water erosion resistance of drainage asphalt mixtures according to claim 1, characterized in that, In step 1), the test specimen of the drainage asphalt mixture is a Marshall specimen prepared from drainage asphalt mixture or a specimen obtained by core cutting of drainage asphalt pavement.

3. The method for evaluating the water erosion resistance of drainage asphalt mixtures according to claim 1, characterized in that, In step 3), during the ultrasonic treatment, the water level should be at least 25 mm above the upper surface of specimen A.

4. The method for evaluating the water erosion resistance of drainage asphalt mixtures according to claim 2, characterized in that, In step 3), during the ultrasonic treatment, the water level should be at least 25 mm above the upper surface of specimen A.

5. The method for evaluating the water erosion resistance of drainage asphalt mixtures according to any one of claims 1 to 4, characterized in that, In step 5), calculate the percentage decrease in mass of specimen B relative to the mass of specimen A using the following formula: X1 = 100% × (m0 - m1) / m0; Where m0 is the mass of specimen A; and m1 is the mass of specimen B.

6. The method for evaluating the water erosion resistance of drainage asphalt mixtures according to any one of claims 1 to 4, characterized in that, Calculate the Kentucky scattering loss ΔS of the specimen using the following formula: △S=100%×(m3 –m4) / m3; Where: m3 is the mass of the specimen before the Kentucky scattering test; m4 is the maximum remaining mass of the specimen after the Kentucky scattering test.

7. The method for evaluating the water erosion resistance of drainage asphalt mixtures according to claim 5, characterized in that, Calculate the Kentucky scattering loss ΔS of the specimen using the following formula: △S=100%×(m3 –m4) / m3; Where: m3 is the mass of the specimen before the Kentucky scattering test; m4 is the maximum remaining mass of the specimen after the Kentucky scattering test.

8. The method for evaluating the water erosion resistance of drainage asphalt mixtures according to any one of claims 1 to 4 and 7, characterized in that, The bond strength of the specimen was calculated as follows: The upper and lower surfaces of the specimen were bonded to the upper and lower steel plate pull heads respectively using strong epoxy adhesive. After curing at room temperature for 4 days, the specimen was cured at 60℃ for 3.5~4.5 hours. The upper and lower steel plate pull heads of the cured specimen were then fixed to a tensile testing machine and stretched at a speed of 4~6 mm / min until the specimen completely fractured. The experiment was completed, and the maximum tensile force F and the cross-sectional area A at the fracture point were recorded. The bond strength of the specimen was calculated using the formula F = F / A. .

9. The method for evaluating the water erosion resistance of drainage asphalt mixtures according to claim 5, characterized in that, The bond strength of the specimen was calculated as follows: The upper and lower surfaces of the specimen were bonded to the upper and lower steel plate pull heads respectively using strong epoxy adhesive. After curing at room temperature for 4 days, the specimen was cured at 60℃ for 3.5~4.5 hours. The upper and lower steel plate pull heads of the cured specimen were then fixed to a tensile testing machine and stretched at a speed of 4~6 mm / min until the specimen completely fractured. The experiment was completed, and the maximum tensile force F and the cross-sectional area A at the fracture point were recorded. The bond strength of the specimen was calculated using the formula F = F / A. .

10. The method for evaluating the water erosion resistance of drainage asphalt mixtures according to claim 6, characterized in that, The bond strength of the specimen was calculated as follows: The upper and lower surfaces of the specimen were bonded to the upper and lower steel plate pull heads respectively using strong epoxy adhesive. After curing at room temperature for 4 days, the specimen was cured at 60℃ for 3.5~4.5 hours. The upper and lower steel plate pull heads of the cured specimen were then fixed to a tensile testing machine and stretched at a speed of 4~6 mm / min until the specimen completely fractured. The experiment was then completed. The maximum tensile force F and the cross-sectional area A at the fracture point of the specimen were recorded. The strength was then calculated according to the formula... =F / A Calculation of the bond strength of the specimen .

11. The method for evaluating the water erosion resistance of drainage asphalt mixtures according to any one of claims 1-4, 7, 9-10, characterized in that, In step 4), the ultrasonic treatment time is 40 hours.

12. The method for evaluating the water erosion resistance of drainage asphalt mixtures according to claim 5, characterized in that, In step 4), the ultrasonic treatment time is 40 hours.

13. The method for evaluating the water erosion resistance of drainage asphalt mixtures according to claim 6, characterized in that, In step 4), the ultrasonic treatment time is 40 hours.

14. The method for evaluating the water erosion resistance of drainage asphalt mixtures according to claim 8, characterized in that, In step 4), the ultrasonic treatment time is 40 hours.

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