A method for simulating ultraviolet aging of asphalt mortar

Abstract

The present invention provides a method for simulating ultraviolet light aging of asphalt mortar, by calculating the equivalent acceleration rate of indoor ultraviolet light aging, and then obtaining the correction coefficient of the equivalent acceleration rate by experiment, so as to establish the equivalent relationship between indoor and outdoor ultraviolet light aging, and finally use the equivalent relationship to perform indoor aging simulation test on asphalt mortar. The method for simulating ultraviolet light aging of asphalt mortar proposed by the present invention shortens the test cycle, saves time cost, and improves test efficiency; in addition, by correcting the equivalent acceleration rate, it can truly simulate the ultraviolet light aging of asphalt mortar in actual application, greatly improve the accuracy of the simulation results, and is very important for studying and improving the ultraviolet light aging problem of asphalt mortar.

Description

Technical Field

[0001] The invention relates to the technical field of road materials, and in particular to a method for simulating ultraviolet light aging of asphalt mortar. Background Art

[0002] Asphalt mortar is a typical viscoelastic material widely used as one of the components of asphalt mixture in highway engineering. Its UV aging problem has always attracted the attention of researchers. At present, UV aging tests can be conducted indoors or outdoors. Outdoor light aging tests directly place the specimens under sunlight. The environmental factors are real and the test results are highly reliable, but the long test cycle is the main problem. Indoor light aging tests usually use high-pressure mercury lamps, xenon lamps, fluorescent lamps, etc. to simulate the total amount of outdoor ultraviolet radiation for testing, but there are problems such as severe heating of the lamp source and the inability to reach the same intensity as the actual ultraviolet radiation, making it difficult to simulate the actual situation of asphalt mortar UV aging. Summary of the invention

[0003] In view of the shortcomings of the prior art described above, the present invention provides a method for simulating ultraviolet light aging of asphalt mortar, by calculating the equivalent acceleration rate of indoor ultraviolet light aging, and then obtaining the correction coefficient of the equivalent acceleration rate from the test, thereby establishing an equivalent relationship between indoor and outdoor ultraviolet light aging, and finally using the equivalent relationship to conduct an indoor aging simulation test on the asphalt mortar. The method for simulating ultraviolet light aging of asphalt mortar proposed in the present invention shortens the test cycle, saves time costs, and improves test efficiency; in addition, by correcting the equivalent acceleration rate, it can truly simulate the ultraviolet light aging of asphalt mortar in actual application, greatly improving the accuracy of the simulation results, which is crucial to studying and improving the ultraviolet light aging problem of asphalt mortar.

[0004] To achieve the above object and other related objects, the present invention provides a method for simulating ultraviolet aging of asphalt mortar, comprising the following steps:

[0005] S1: Preparation of asphalt mortar specimens;

[0006] S2: Determine the radiation intensity and radiation time of indoor UV aging that is equivalent to the outdoor radiation intensity;

[0007] S3: Dividing the asphalt mortar specimens into a first test group and a second test group, wherein the first test group is placed under indoor ultraviolet light for a light aging test, and the second test group is placed under outdoor ultraviolet light for a light aging test;

[0008] S4: After the light aging test, the aged asphalt mortar specimens were subjected to frequency scanning at different temperatures to obtain the complex shear modulus of the first test group and the second test group;

[0009] S5: obtaining a correction coefficient K for indoor UV aging according to the complex shear modulus of the first test group and the second test group;

[0010] S6: Perform an indoor aging simulation test on the asphalt mortar specimen according to the correction factor K.

[0011] Optionally, step S2 includes the following steps:

[0012] Determine outdoor radiation intensity;

[0013] The indoor radiation intensity is set, and the equivalent acceleration rate of indoor ultraviolet aging is calculated. The indoor radiation time equivalent to the outdoor radiation of the asphalt mortar specimen for half a year and one year is obtained from the equivalent acceleration rate.

[0014] Optionally, the equivalent acceleration rate A 1 =Q R / Q Z , where Q R is the total indoor radiation in the same time, Q Z is the total amount of outdoor radiation in the same period of time.

[0015] Optionally, in step S3, an indoor ultraviolet light aging test is performed on the first test group using an LED light source.

[0016] Optionally, in step S3, the second test group is placed in a natural open space, sealed with a glass cover, and then subjected to an outdoor ultraviolet light aging test.

[0017] Optionally, step S4 includes the following steps:

[0018] Performing strain scanning on the unaged asphalt mortar specimen using a dynamic shear rheometer to obtain the linear viscoelastic range strain of the asphalt mortar specimen;

[0019] The frequency range, temperature and linear viscoelastic range strain are set, and the frequency scans are performed at different temperatures on the first test group and the second test group after the aging test.

[0020] Optionally, the frequency range is 0.1 Hz to 60 Hz.

[0021] Optionally, the temperature is set between 0°C and 45°C.

[0022] Optionally, the linear viscoelastic range strain is 0.01%.

[0023] Optionally, step S5 includes the following steps:

[0024] Calculate the dispersion coefficient C of the complex shear modulus of the first test group and the second test group at different temperatures V ;

[0025] The range of the correction coefficient K is obtained, where the dispersion coefficient C V At the minimum temperature, the minimum percentage difference between the complex shear moduli of the first test group and the second test group is the minimum value of the correction coefficient K, and the maximum percentage difference between the complex shear moduli of the first test group and the second test group is the maximum value of the correction coefficient K;

[0026] Establish the equivalence between indoor and outdoor UV aging.

[0027] Optionally, the dispersion coefficient in,

[0028] Optionally, when the complex shear modulus of the first test group is less than the complex shear modulus of the second test group, the equivalent relationship is A 2 =(1-K)A 1 .

[0029] Optionally, when the complex shear modulus of the first test group is greater than the complex shear modulus of the second test group, the equivalent relationship is A 2 =(1+K)A 1 .

[0030] Optionally, step S6 includes the following steps:

[0031] Calculate the corrected indoor ultraviolet aging radiation time equivalent to the outdoor radiation intensity according to the equivalent relationship;

[0032] An indoor aging simulation test is performed on the asphalt mortar specimen according to the corrected indoor ultraviolet aging radiation time.

[0033] The method for simulating ultraviolet aging of asphalt mortar provided by the present invention has at least the following technical effects:

[0034] The method for simulating ultraviolet light aging of asphalt mortar provided by the present invention calculates the equivalent acceleration rate of indoor ultraviolet light aging, and then obtains the correction coefficient of the equivalent acceleration rate from the test, thereby establishing the equivalent relationship between indoor and outdoor ultraviolet light aging, and finally uses the equivalent relationship to perform an indoor aging simulation test on the asphalt mortar. The method for simulating ultraviolet light aging of asphalt mortar proposed by the present invention shortens the test cycle, saves time cost, and improves test efficiency; in addition, by correcting the equivalent acceleration rate, it can truly simulate the ultraviolet light aging of asphalt mortar in actual application, greatly improving the accuracy of the simulation results, which is very important for studying and improving the ultraviolet light aging problem of asphalt mortar. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1A flow chart showing a method for simulating UV aging of asphalt mortar provided as an embodiment.

[0036] Figure 2a-2b Shown is the scanning result of the first test group in step S4 of the embodiment.

[0037] Figure 3a-3b Shown is the scanning result of the second test group in step S4 of the embodiment. DETAILED DESCRIPTION

[0038] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0039] It should be noted that the illustrations provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Although the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation, the form, quantity, positional relationship and proportion of each component in actual implementation can be changed at will under the premise of realizing the technical solution of this party, and the component layout form may also be more complicated.

[0040] Example

[0041] This embodiment provides a method for simulating ultraviolet aging of asphalt mortar. Figure 1 As shown, the specific steps include:

[0042] Step S1: preparing asphalt mortar specimens;

[0043] First, the optimal asphalt-to-stone ratio of the asphalt mixture is calculated, that is, the optimal mass ratio of asphalt to mineral material in the asphalt mixture. The asphalt-to-stone ratio is one of the indicators of asphalt dosage, and its dosage directly affects the road quality. A road with a large asphalt-to-stone ratio is prone to oil spillage, and vice versa, it affects the strength and waterproofing effect. Specifically, the optimal asphalt-to-stone ratio can be obtained through the Marshall test, which is well known to those skilled in the art and will not be described in detail here.

[0044] Next, the optimal asphalt-to-stone ratio of asphalt mortar is calculated. As an example, the equivalent asphalt content in asphalt mortar can be calculated based on the principle that the asphalt content adsorbed by mineral aggregates and the powder-to-binder ratio in asphalt mortar are consistent with the asphalt mixture. The aggregate ratio in asphalt mortar is proportionally enlarged according to the aggregate ratio in asphalt mixture, thus obtaining the asphalt-to-stone ratio of asphalt mortar;

[0045] Finally, asphalt mortar specimens were made. As an example, the asphalt mortar was batched and baked according to the optimal asphalt-stone ratio and mix ratio. The asphalt mortar mix ratio is shown in Table 1. After the asphalt mortar was mixed according to the test sub-item T0702 method in JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", the SGC was used to set the number of rotary compactions to compact the asphalt mortar into a cylindrical specimen with a diameter of 100 mm. After waiting for cooling for more than 60 minutes, the asphalt mortar specimen was demoulded, and the cylindrical asphalt mortar specimen was cut into small asphalt mortar specimens of uniform specifications and suitable for the rectangular fixture of the dynamic shear rheometer using a precision cutting machine.

[0046] Table 1 Asphalt mortar mix ratio

[0047]

[0048] Step S2: Determine the radiation intensity and radiation time of indoor ultraviolet light aging that is equivalent to the outdoor radiation intensity;

[0049] First, determine the outdoor radiation intensity. The outdoor radiation intensity needs to be determined according to the region and time. Taking Hunan as an example, the annual solar radiation under the actual weather conditions in Hunan is 4190MJ / m 2 ~5016MJ / m 2 The annual sunshine hours are 1400h~2200h, and the annual average sunshine time under standard light is 3.1h~3.8h. Assuming that ultraviolet rays account for 5% of the annual solar radiation, the annual average ultraviolet radiation in Hunan is 230MJ / m 2 , annual average daily total amount of ultraviolet radiation Q Z It is 0.01243W.

[0050] Next, determine the indoor UV aging radiation intensity and radiation time that is equivalent to the outdoor radiation intensity. As an example, set the indoor radiation intensity to 30mw / cm 2 , aging 23h per day, the total radiation per day is Q R That is 0.69W, the equivalent acceleration rate of indoor ultraviolet light aging is A 1 =Q R / Q Z ≈55.51, taking the average annual sunshine hours in Hunan as 1800h, that is, one year of outdoor radiation is equivalent to 1800h / 55.51=32.42h of indoor radiation, and half a year of outdoor radiation is equivalent to 16.21h of indoor radiation.

[0051] Step S3: dividing the asphalt mortar specimens into a first test group and a second test group, wherein the first test group is placed under indoor ultraviolet light for a light aging test, and the second test group is placed under outdoor ultraviolet light for a light aging test;

[0052] As an example, for the first test group, an indoor ultraviolet light aging test is performed on the first test group using an LED light source, with a radiation intensity of 30 mw / cm 2 , and further divided the first test group into two groups of asphalt mortar specimens, setting the radiation time of one group to 16.21 h to simulate the outdoor radiation for half a year, and setting the radiation time of the other group to 32.42 h to simulate the outdoor radiation for one year.

[0053] As an example, the second test group was placed in a natural open place. In order to consider only the aging caused by natural light radiation to the second test group and prevent water damage, the second test group was sealed with a glass cover and then subjected to natural light radiation aging. Similarly, the second test group was divided into two groups of asphalt mortar specimens, one of which was placed outdoors for half a year and the other was placed outdoors for one year.

[0054] Step S4: After the light aging test is completed, the aged asphalt mortar specimens are subjected to frequency scanning at different temperatures to obtain the complex shear modulus of the first test group and the second test group;

[0055] Asphalt materials are typical viscoelastic materials with obvious sensitivity to temperature. Therefore, in order to ensure the reproducibility of the measurement results, it is necessary to first determine the linear viscoelastic range of the material. As an example, a dynamic shear rheometer is used to scan an unaged asphalt mortar specimen with a scanning frequency of 0.1Hz to 60Hz, a scanning temperature of 0°C, and a strain range of 0.001% to 0.1%. According to the method for determining the linear viscoelastic range, it is stipulated that the decrease in the complex shear modulus of the viscoelastic material with the increase of strain in the strain scanning result is within 5% as the linear viscoelastic range, and the linear viscoelastic range strain obtained by scanning is 0.01%.

[0056] The first test group and the second test group after the aging test were subjected to frequency scanning at different temperatures, with the scanning frequency ranging from 0.1 Hz to 60 Hz and the scanning temperature ranging from 0°C to 45°C. Specifically, the scanning temperatures were set to 0°C, 15°C, 30°C and 45°C, respectively, and the linear viscoelastic range strain was 0.01%. The scanning results of the first test group are as follows: Figure 2a and 2b As shown, Figure 2a It shows the variation of the complex shear modulus of the specimen with frequency under indoor radiation for 16.21h; Figure 2b The display shows the variation of the complex shear modulus of the specimen with frequency under the condition of 32.42h of indoor radiation. The scanning results of the second test group are as follows Figure 3a and 3b As shown, Figure 3a It shows the variation of the complex shear modulus of the specimen with frequency when it is exposed to outdoor radiation for half a year; Figure 3b Shown is the variation of the complex shear modulus of the specimen with frequency after one year of outdoor radiation.

[0057] Step S5: obtaining a correction coefficient for indoor ultraviolet aging according to the complex shear moduli of the first test group and the second test group;

[0058] First of all, Figure 2a-2b The data analysis was performed on the scanning results shown in 3a to 3b, and the discrete coefficient C of the complex shear modulus at each temperature was calculated according to the following formulas (1) to (3): V The calculation results are shown in Table 2.

[0059]

[0060]

[0061]

[0062] Table 2 Discrete coefficient C of complex shear modulus of samples with different aging time and aging environment at different scanning temperatures V

[0063]

[0064] It can be seen from Table 2 that the dispersion coefficient C of the complex shear modulus when the scanning temperature is 15°C V Minimum, coefficient of dispersion C V The minimum represents the minimum discreteness of the parallel test data, that is, in this case a more accurate reference value can be calculated. At a scanning temperature of 15°C, the percentage difference between the indoor and outdoor complex shear moduli obtained by different scanning frequencies is shown in Table 3, where the outdoor complex shear modulus is greater than the indoor complex shear modulus. The minimum percentage difference between the indoor and outdoor complex shear moduli is selected as the minimum value of the correction coefficient K, that is, the minimum value of the correction coefficient K is 11.38%; the maximum percentage difference between the indoor and outdoor complex shear moduli is selected as the maximum value of the correction coefficient K, that is, the maximum value of the correction coefficient K is 13.87%. Finally, the range of the correction coefficient K is 11.38% to 13.87%, and the equivalent relationship A between indoor and outdoor ultraviolet aging is established. 2 =(1-K)A 1 .

[0065] Table 3: Percentage difference between indoor and outdoor complex shear modulus under frequency scanning at 15℃

[0066]

[0067]

[0068] Step S6: performing an indoor aging simulation test on the asphalt mortar specimen according to the correction coefficient K;

[0069] As an example, according to the equivalence relation A 2 =(1-K)A 1 Calculate the corrected indoor UV radiation time equivalent to the outdoor radiation intensity. For example, the average annual sunshine hours in Hunan is 1800h, which means that one year of outdoor radiation is equivalent to 1800h / A indoor radiation. 2 =1800h / (1-K)A 1 In this embodiment, A 1 =55.51, K takes the median value of its range as 12.625%, that is, in Hunan area, outdoor radiation for one year is equivalent to indoor radiation for 37.1h.

[0070] As above, the corrected indoor UV radiation time equal to the outdoor radiation amount was obtained through the test. Then, the indoor aging simulation test of the asphalt mortar specimen was carried out according to the corrected indoor UV aging radiation time. As an example, the indoor UV aging test of the asphalt mortar specimen was carried out using an LED light source, and the radiation intensity was 30mw / cm 2 , setting the radiation time to 37.1h to simulate one year of outdoor radiation. In other optional embodiments, the indoor radiation time is adjusted accordingly according to the outdoor radiation time to be simulated.

[0071] In summary, the present invention provides a method for simulating ultraviolet light aging of asphalt mortar, by calculating the equivalent acceleration rate of indoor ultraviolet light aging, and then obtaining the correction coefficient of the equivalent acceleration rate from the test, thereby establishing the equivalent relationship between indoor and outdoor ultraviolet light aging, and finally using the equivalent relationship to conduct an indoor aging simulation test on the asphalt mortar. The method for simulating ultraviolet light aging of asphalt mortar proposed in the present invention shortens the test cycle, saves time costs, and improves test efficiency; in addition, by correcting the equivalent acceleration rate, it can truly simulate the ultraviolet light aging of asphalt mortar in actual application, greatly improving the accuracy of the simulation results, which is crucial to studying and improving the ultraviolet light aging problem of asphalt mortar.

[0072] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for simulating ultraviolet aging of asphalt mortar, characterized in that: The following steps are involved: S1: Preparation of asphalt mortar specimens; S2: Determine the total amount of outdoor radiation Q Z , set the total indoor radiation Q in the same time R , the equivalent acceleration rate of indoor ultraviolet aging is calculated to be A1 = Q R / Q Z , the indoor radiation time equivalent to the outdoor radiation of the asphalt mortar specimen for half a year and one year is obtained from the equivalent acceleration rate; S3: Dividing the asphalt mortar specimens into a first test group and a second test group, wherein the first test group is placed under indoor ultraviolet light for a light aging test, and the second test group is placed under outdoor ultraviolet light for a light aging test; S4: After the light aging test, the aged asphalt mortar specimens were subjected to frequency scanning at different temperatures to obtain the complex shear modulus of the first test group and the second test group; S5: Calculate the coefficient of dispersion of the complex shear modulus of the first test group and the second test group at different temperatures in, The range of correction coefficient K for indoor UV aging is obtained, where the dispersion coefficient C V At the minimum temperature, the minimum percentage difference between the complex shear modulus of the first test group and the second test group is the minimum value of the correction coefficient K, and the maximum percentage difference between the complex shear modulus of the first test group and the second test group is the maximum value of the correction coefficient K; an equivalent relationship between indoor and outdoor ultraviolet light aging is established, when the complex shear modulus of the first test group is less than the complex shear modulus of the second test group, the equivalent relationship is A2=(1-K)A1, and when the complex shear modulus of the first test group is greater than the complex shear modulus of the second test group, the equivalent relationship is A2=(1+K)A1; S6: Calculate the corrected indoor ultraviolet aging radiation time equivalent to the outdoor radiation intensity based on the equivalent relationship; and perform an indoor aging simulation test on the asphalt mortar specimen based on the corrected indoor ultraviolet aging radiation time.

2. The method for simulating ultraviolet aging of asphalt mortar according to claim 1, characterized in that: In step S3, an indoor ultraviolet light aging test is performed on the first test group using an LED light source.

3. The method for simulating ultraviolet aging of asphalt mortar according to claim 1, characterized in that: In step S3, the second test group is placed in a natural open space, sealed with a glass cover, and then subjected to an outdoor ultraviolet light aging test.

4. The method for simulating ultraviolet aging of asphalt mortar according to claim 1, characterized in that: Step S4 includes the following steps: Performing strain scanning on the unaged asphalt mortar specimen using a dynamic shear rheometer to obtain the linear viscoelastic range strain of the asphalt mortar specimen; The frequency range, temperature and linear viscoelastic range strain are set, and the frequency scans are performed at different temperatures on the first test group and the second test group after the aging test.

5. The method for simulating ultraviolet aging of asphalt mortar according to claim 4, characterized in that: The frequency range is 0.1 Hz to 60 Hz.

6. The method for simulating ultraviolet aging of asphalt mortar according to claim 4, characterized in that: The temperature is set between 0°C and 45°C.

7. The method for simulating ultraviolet aging of asphalt mortar according to claim 4, characterized in that: The linear viscoelastic range strain is 0.01%.

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