A method for testing asphalt ultraviolet-visible absorption spectrum based on integrating sphere

Abstract

The present invention discloses a method for testing asphalt ultraviolet-visible absorption spectra based on an integrating sphere, which belongs to the field of road petroleum asphalt and solves the problem that asphalt cannot be uniformly mixed with powder to prepare a sample suitable for an integrating sphere method. The method is as follows: an asphalt sample is added to a n-heptane-toluene mixture to form an asphalt dispersion; BaSO4 is added to the asphalt dispersion, and n-heptane and toluene are removed by vacuum distillation after sealing and standing, so as to obtain BaSO4 powder with asphalt uniformly adsorbed on the surface as a sample to be tested; BaSO4 is added to a n-heptane-toluene mixture, and n-heptane and toluene are removed by vacuum distillation after sealing and standing, so as to obtain BaSO4 powder with no asphalt adsorbed on the surface as a blank sample; the sample to be tested and the blank sample are prepared into test pieces respectively, and tested using an ultraviolet-visible spectrometer equipped with an integrating sphere. The method of the present invention can obtain a more complete, accurate, and more characteristic asphalt ultraviolet-visible spectrum.

Description

Technical Field

[0001] The invention belongs to the field of road petroleum asphalt, and in particular relates to an asphalt ultraviolet-visible absorption spectrum testing method based on an integrating sphere. Background Art

[0002] During the service of asphalt pavement, the asphalt on its surface will inevitably age due to exposure to solar radiation. Adding UV absorbers to asphalt is one of the main methods to improve the UV aging resistance of asphalt. However, different types of UV absorbers have different UV absorption characteristics and different compatibility with asphalt. By analyzing and characterizing the absorption characteristics of asphalt in the UV-visible region, UV absorbers suitable for specific asphalt can be screened out, which helps to improve the UV aging resistance of asphalt, increase the service life of asphalt pavement, reduce maintenance frequency, and reduce energy and material consumption in road operations, thereby reducing the resulting carbon emissions.

[0003] At present, the UV-visible spectrum analysis of asphalt mainly adopts the cuvette method, that is, the asphalt is dispersed in an organic solvent and tested in the form of a liquid sample. The organic solvents used are mainly n-heptane, toluene, etc. In this method, the asphaltene with a larger molecular weight in the asphalt cannot be dissolved by the above solvents, and is mainly dispersed in the solvent in the form of particles with a diameter of 1~5μm, which will cause Rayleigh scattering in the UV-visible spectrum test and interfere with the characterization of the absorption characteristics. Although organic solvents such as trichloroethylene can completely dissolve asphalt, when used as solvents, they will strongly interfere with the test in the wavelength range below 265nm, and cannot be used for the test of the UV-visible absorption spectrum of asphalt. At present, the main difficulty in using the integrating sphere method to test the UV-visible spectrum of asphalt is that asphalt is a highly viscous material at room temperature and pressure, and it is impossible to mix it evenly with powder to prepare a sample suitable for the integrating sphere method. Summary of the invention

[0004] The purpose of the present invention is to provide an asphalt UV-visible absorption spectrum testing method based on an integrating sphere to solve the problem that asphalt cannot be uniformly mixed with powder to prepare a sample suitable for the integrating sphere method.

[0005] The technical solution of the present invention is: a method for testing asphalt ultraviolet-visible absorption spectrum based on an integrating sphere, comprising the following steps:

[0006] A. Prepare a n-heptane-toluene mixed solution, add the asphalt sample into the mixed solution, and perform ultrasonic treatment to evenly disperse the asphalt sample in the mixed solution to form an asphalt dispersion;

[0007] B. Add a certain amount of BaSO4 to the asphalt dispersion, perform ultrasonic treatment to evenly disperse the BaSO4, and obtain an asphalt-BaSO4 mixed dispersion. The asphalt-BaSO4 mixed dispersion is sealed and allowed to stand for 24-36 hours, and then the n-heptane and toluene are removed by vacuum distillation to obtain a BaSO4 powder with asphalt evenly adsorbed on the surface as a sample to be tested;

[0008] C. Prepare a n-heptane-toluene mixed solution, add BaSO4 thereto, perform ultrasonic treatment to evenly disperse the BaSO4, and obtain a BaSO4 dispersion. The BaSO4 dispersion is sealed and allowed to stand for 24-36 hours, and then the n-heptane and toluene are removed by reduced pressure distillation to obtain a BaSO4 powder with no asphalt adsorbed on the surface as a blank sample;

[0009] D. Prepare the sample to be tested and the blank sample into test pieces that can be tested by UV-visible spectrometer by using a tablet pressing method, and use a UV-visible spectrometer equipped with an integrating sphere to test the UV-visible absorption spectrum of the test piece to obtain the UV-visible absorption spectrum curve of the sample to be tested.

[0010] As a further improvement of the present invention, in step A and step C, the volume ratio of n-heptane to toluene in the n-heptane-toluene mixture is 60-150:1.

[0011] As a further improvement of the present invention, in step A, the concentration of asphalt in the n-heptane-toluene mixture is 0.2~2.0 mg / mL; in step B, the concentration of the added BaSO4 in the n-heptane-toluene mixture is 2~18 mg / mL; the mass ratio of asphalt to BaSO4 is 1:9-19.

[0012] As a further improvement of the present invention, the asphalt is road petroleum asphalt, including one of various grades of base asphalt, SBS modified asphalt, rubber modified asphalt, and SBS-rubber composite modified asphalt.

[0013] The beneficial effects of the present invention are:

[0014] The present invention adopts a method of dissolving and dispersing first and then evaporating the solvent to prepare an asphalt-BaSO4 solid sample suitable for ultraviolet-visible spectrum testing, thereby solving the problem of uniformly dispersing high-viscosity asphalt in powder for sample preparation.

[0015] The present invention adopts the integrating sphere method to directly test the asphalt solid sample, thereby solving the problem that when the asphalt solution / suspension is tested by the cuvette method, the scattering generated by the undissolved components interferes with the test result.

[0016] The present invention tests the ultraviolet-visible spectrum of asphalt by the integrating sphere method, and can directly obtain the ultraviolet-visible spectrum of different asphalts in the entire band, thereby achieving direct characterization of the absorption characteristics of asphalt in the ultraviolet-visible region.

[0017] The present invention can perform full-band ultraviolet-visible light spectrum testing on base asphalt, SBS modified asphalt, rubber modified asphalt and SBS-rubber composite modified asphalt.

[0018] In actual application, the UV-visible spectrum of aged asphalt can be tested by the method of the present invention to obtain a more complete, accurate and characteristic UV-visible spectrum of asphalt, and the most suitable anti-UV aging agent for road petroleum asphalt can be selected to provide data support for accurately improving the UV aging resistance of asphalt and increasing the aging resistance of asphalt pavement. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a comparison diagram of the ultraviolet-visible spectrum of Example 1 of the present invention;

[0020] Figure 2 is a comparison diagram of the ultraviolet-visible spectrum of Comparative Example 1 of the present invention;

[0021] Figure 3 is a comparison diagram of the UV-visible spectrum of Example 2 of the present invention;

[0022] Figure 4 is a comparison diagram of the UV-visible spectrum of Comparative Example 2 of the present invention;

[0023] Figure 5 is a comparison diagram of the UV-visible spectrum of Example 3 of the present invention;

[0024] Figure 6 is a comparison diagram of the ultraviolet-visible spectrum of Comparative Example 3 of the present invention;

[0025] Figure 7 is a comparison diagram of the UV-visible spectrum of Example 4 of the present invention;

[0026] Figure 8 It is a comparison diagram of the UV-visible spectrum of Comparative Example 4 of the present invention. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with specific implementation modes.

[0028] The n-heptane, toluene and BaSO4 used in the following examples and comparative examples were all of analytical grade.

[0029] The UV-visible spectrometer used in the following examples and comparative examples is a Shimadzu UV-3600 UV-visible-near infrared spectrophotometer equipped with an integrating sphere. The selected UV-visible spectrum test range is 200-800 nm, and the scanning interval is 0.05 nm.

[0030] Embodiment 1,

[0031] The matrix asphalt was selected for testing.

[0032] A method for testing asphalt ultraviolet-visible absorption spectrum based on an integrating sphere comprises the following steps:

[0033] A. Prepare a n-heptane-toluene mixed solution with 500 mL of n-heptane and 5 mL of toluene, add 0.200 g of matrix asphalt therein, and perform ultrasonic treatment for 30 minutes to evenly disperse the matrix asphalt in the mixed solution to form an asphalt dispersion;

[0034] B. Add 1.800 g of BaSO4 to the asphalt dispersion, continue ultrasonic treatment for 30 minutes to evenly disperse the BaSO4 to obtain an asphalt-BaSO4 mixed dispersion, seal the asphalt-BaSO4 mixed dispersion and let it stand for 24 hours, then remove n-heptane and toluene by vacuum distillation to obtain a BaSO4 powder with the matrix asphalt evenly adsorbed on the surface as a sample to be tested;

[0035] C. Prepare a n-heptane-toluene mixed solution by mixing 500 mL of n-heptane and 5 mL of toluene, add 1.800 g of BaSO4 thereto, and perform ultrasonic treatment for 30 minutes to evenly disperse the BaSO4 to form a BaSO4 dispersion. The BaSO4 dispersion is sealed and allowed to stand for 24 hours, and then the n-heptane and toluene are removed by vacuum distillation to obtain a BaSO4 powder as a blank control sample;

[0036] D. Prepare the test sample and the blank control sample into test pieces by tablet pressing method, and conduct solid UV-visible spectrum test on the test piece by UV-visible spectrometer to obtain the UV-visible absorption spectrum curve of the test matrix asphalt, see Figure 1 .

[0037] Comparative Example 1

[0038] The base asphalt in Example 1 was analyzed by UV-visible spectroscopy using a cuvette method, and the method is as follows:

[0039] S1. Prepare a n-heptane-toluene mixed solution by mixing 500 mL of n-heptane and 5 mL of toluene, add 0.200 g of matrix asphalt therein, and perform ultrasonic treatment for 30 minutes to evenly disperse the matrix asphalt in the mixed solution to form an asphalt dispersion;

[0040] S2. The asphalt dispersion is tested by a UV-visible spectrometer to obtain a UV-visible spectrum of the matrix asphalt based on the cuvette method, see Figure 2 .

[0041] Depend on Figure 1 , Figure 2 By comparison, it can be seen that the UV-visible spectrum measured by the method of the present invention can completely and clearly measure the absorption curve of the matrix asphalt in the UV-visible light region. Compared with the traditional cuvette method, this method has a larger test range and more obvious signal characteristics.

[0042] Embodiment 2,

[0043] SBS modified asphalt was selected for testing.

[0044] A method for testing asphalt ultraviolet-visible absorption spectrum based on an integrating sphere comprises the following steps:

[0045] A. Prepare a n-heptane-toluene mixed solution by mixing 600 mL of n-heptane and 10 mL of toluene, add 0.122 g of SBS modified asphalt therein, and perform ultrasonic treatment for 30 minutes to evenly disperse the SBS modified asphalt in the mixed solution to form an asphalt dispersion;

[0046] B. Add 2.318 g of BaSO4 to the asphalt dispersion, continue ultrasonic treatment for 30 minutes to evenly disperse the BaSO4 to obtain an asphalt-BaSO4 mixed dispersion, seal the asphalt-BaSO4 mixed dispersion and let it stand for 36 hours, then remove n-heptane and toluene by vacuum distillation to obtain a BaSO4 powder with SBS modified asphalt evenly adsorbed on the surface as a sample to be tested;

[0047] C. Prepare an n-heptane-toluene mixed solution by mixing 600 mL of n-heptane and 10 mL of toluene, add 2.318 g of BaSO4 thereto, and perform ultrasonic treatment for 30 minutes to evenly disperse the BaSO4 to form a BaSO4 dispersion. The BaSO4 dispersion is sealed and allowed to stand for 36 hours, and then the n-heptane and toluene are removed by vacuum distillation to obtain a BaSO4 powder as a blank control sample;

[0048] D. Prepare the test sample and the blank control sample into test pieces by tablet pressing method, and conduct solid UV-visible spectrum test on the test piece by UV-visible spectrometer to obtain the UV-visible absorption spectrum curve of the test matrix asphalt, see Figure 3 .

[0049] Comparative Example 2

[0050] The SBS modified asphalt in Example 2 was analyzed by UV-visible spectroscopy using a cuvette method as follows:

[0051] S1. Prepare an n-heptane-toluene mixed solution by mixing 600 mL of n-heptane and 10 mL of toluene, add 0.122 g of SBS modified asphalt thereto, and perform ultrasonic treatment for 30 minutes to uniformly disperse the SBS modified asphalt in the mixed solution to form an asphalt dispersion;

[0052] S2. The asphalt dispersion is tested by a UV-visible spectrometer to obtain a UV-visible spectrum of the SBS modified asphalt based on the cuvette method, see Figure 4 .

[0053] Depend on Figure 3 , Figure 4 By comparison, it can be seen that the UV-visible spectrum measured by the method of the present invention can completely and clearly measure the absorption curve of SBS modified asphalt in the UV-visible light region. Compared with the traditional cuvette method, this method has a larger test range and more obvious signal characteristics.

[0054] Embodiment 3,

[0055] Rubber modified asphalt was selected for testing.

[0056] A method for testing asphalt ultraviolet-visible absorption spectrum based on an integrating sphere comprises the following steps:

[0057] A. Prepare a n-heptane-toluene mixed solution by mixing 600 mL of n-heptane and 4 mL of toluene, add 1.208 g of rubber-modified asphalt therein, and perform ultrasonic treatment for 30 minutes to evenly disperse the rubber-modified asphalt in the mixed solution to form an asphalt dispersion;

[0058] B. Add 10.872 g of BaSO4 to the asphalt dispersion, continue ultrasonic treatment for 30 minutes to evenly disperse the BaSO4 to obtain an asphalt-BaSO4 mixed dispersion, seal the asphalt-BaSO4 mixed dispersion and let it stand for 30 hours, then remove n-heptane and toluene by vacuum distillation to obtain a BaSO4 powder with rubber-modified asphalt evenly adsorbed on the surface as a sample to be tested;

[0059] C. Prepare an n-heptane-toluene mixed solution by adding 600 mL of n-heptane and 4 mL of toluene, add 10.872 g of BaSO4 thereto, and perform ultrasonic treatment for 30 minutes to evenly disperse the BaSO4 to form a BaSO4 dispersion. The BaSO4 dispersion is sealed and allowed to stand for 30 hours, and then the n-heptane and toluene are removed by vacuum distillation to obtain BaSO4 powder as a blank control sample;

[0060] D. Prepare the test sample and the blank control sample into test pieces by tablet pressing method, and conduct solid UV-visible spectrum test on the test piece by UV-visible spectrometer to obtain the UV-visible absorption spectrum curve of the test matrix asphalt, see Figure 5 .

[0061] Comparative Example 3

[0062] The rubber-modified asphalt in Example 3 was analyzed by UV-visible spectroscopy using a cuvette method, and the method is as follows:

[0063] S1. Prepare an n-heptane-toluene mixed solution by mixing 500 mL of n-heptane and 5 mL of toluene, add 1.208 g of rubber-modified asphalt therein, and perform ultrasonic treatment for 30 minutes to uniformly disperse the rubber-modified asphalt in the mixed solution to form an asphalt dispersion;

[0064] S2. The asphalt dispersion is tested by a UV-visible spectrometer to obtain a UV-visible spectrum of the rubber-modified asphalt based on the cuvette method, see Figure 6 .

[0065] Depend on Figure 5 , Figure 6 By comparison, it can be seen that the UV-visible spectrum measured by the method of the present invention can completely and clearly measure the absorption curve of rubber-modified asphalt in the UV-visible light region. Compared with the traditional cuvette method, this method has a larger test range and more obvious signal characteristics.

[0066] Embodiment 4,

[0067] SBS-rubber composite modified asphalt was selected for testing.

[0068] A method for testing asphalt ultraviolet-visible absorption spectrum based on an integrating sphere comprises the following steps:

[0069] A. Prepare a n-heptane-toluene mixed solution by mixing 660 mL of n-heptane and 10 mL of toluene, add 0.140 g of SBS-rubber composite modified asphalt therein, and perform ultrasonic treatment for 30 minutes to uniformly disperse the SBS-rubber composite modified asphalt in the mixed solution to form an asphalt dispersion;

[0070] B. Add 1.340 g of BaSO4 to the asphalt dispersion, continue ultrasonic treatment for 30 minutes to evenly disperse the BaSO4 to obtain an asphalt-BaSO4 mixed dispersion, seal the asphalt-BaSO4 mixed dispersion and let it stand for 24 hours, then remove n-heptane and toluene by vacuum distillation to obtain a BaSO4 powder with SBS-rubber composite modified asphalt evenly adsorbed on the surface as a sample to be tested;

[0071] C. Prepare an n-heptane-toluene mixed solution by mixing 660 mL of n-heptane and 10 mL of toluene, add 1.340 g of BaSO4 thereto, and perform ultrasonic treatment for 30 minutes to evenly disperse the BaSO4 to form a BaSO4 dispersion. The BaSO4 dispersion is sealed and allowed to stand for 24 hours, and then the n-heptane and toluene are removed by vacuum distillation to obtain a BaSO4 powder as a blank control sample;

[0072] D. Prepare the test sample and the blank control sample into test pieces by tablet pressing method, and conduct solid UV-visible spectrum test on the test piece by UV-visible spectrometer to obtain the UV-visible absorption spectrum curve of the test matrix asphalt, see Figure 7 .

[0073] Comparative Example 4

[0074] The SBS-rubber composite modified asphalt in Example 3 was analyzed by UV-visible spectroscopy using a cuvette method, and the method is as follows:

[0075] S1. Prepare an n-heptane-toluene mixed solution by mixing 660 mL of n-heptane and 10 mL of toluene, add 0.140 g of SBS-rubber composite modified asphalt thereto, and perform ultrasonic treatment for 30 minutes to uniformly disperse the SBS-rubber composite modified asphalt in the mixed solution to form an asphalt dispersion;

[0076] S2. The asphalt dispersion is tested by UV-visible spectrometer to obtain the UV-visible spectrum of SBS-rubber composite modified asphalt based on the cuvette method, see Figure 8 .

[0077] Depend on Figure 7 , Figure 8 By comparison, it can be seen that the UV-visible spectrum measured by the method of the present invention can completely and clearly measure the absorption curve of rubber-modified asphalt in the UV-visible light region. Compared with the traditional cuvette method, this method has a larger test range and more obvious signal characteristics.

[0078] It should be noted that: in the comparative example, asphalt is dissolved in a n-heptane-toluene mixture, and the saturated components, aromatic components and colloid components in the asphalt can be dissolved in the mixture and exist in the form of a solution, but the asphaltene component in the asphalt cannot be completely dissolved in the mixture due to its large molecular weight, but exists in the mixture in the form of particles with a diameter of 1 to 5 microns, forming a suspension, which causes ultraviolet light and visible light to refract and reflect. The refraction and reflection intensity is large, which will significantly affect or even cover the light signal detected by the instrument during the test, and the resulting spectrum is a distorted ultraviolet-visible absorption spectrum under the influence of refraction and reflection caused by asphaltene particles. After the barium sulfate powder of the asphalt prepared by the method of the present invention is prepared into a sample by a tabletting method, it is tested using an ultraviolet-visible spectrometer equipped with an integrating sphere. Since barium sulfate itself has the characteristics of high reflection and non-light absorption, the instrument detects the ultraviolet-visible absorption signal of the asphalt in the test sample, and the resulting spectrum is the ultraviolet-visible absorption spectrum of the asphalt. The present invention avoids the influence of reflection and refraction of signal light in the cuvette method and can directly measure the absorption characteristics of the sample. Therefore, there are certain differences in the peak positions of the spectra of the above-mentioned groups of embodiments and comparative examples.

Claims

1. A method for testing asphalt ultraviolet-visible absorption spectra based on an integrating sphere, characterized in that The following steps are involved: A. Prepare a n-heptane-toluene mixed solution, add the asphalt sample into the mixed solution, and perform ultrasonic treatment to evenly disperse the asphalt sample in the mixed solution to form an asphalt dispersion; B. Add BaSO4 to the asphalt dispersion and perform ultrasonic treatment to evenly disperse the BaSO4 to obtain an asphalt-BaSO4 mixed dispersion. The asphalt-BaSO4 mixed dispersion is sealed and allowed to stand for 24-36 hours, and then the n-heptane and toluene are removed by reduced pressure distillation to obtain a BaSO4 powder with asphalt evenly adsorbed on the surface as a sample to be tested; C. Prepare a n-heptane-toluene mixed solution, add BaSO4 thereto, perform ultrasonic treatment to evenly disperse the BaSO4, and obtain a BaSO4 dispersion. The BaSO4 dispersion is sealed and allowed to stand for 24-36 hours, and then the n-heptane and toluene are removed by reduced pressure distillation to obtain a BaSO4 powder with no asphalt adsorbed on the surface as a blank sample; D. Prepare the sample to be tested and the blank sample into test pieces that can be tested by UV-visible spectrometer by using a tablet pressing method, and use a UV-visible spectrometer equipped with an integrating sphere to test the UV-visible absorption spectrum of the test piece to obtain the UV-visible absorption spectrum curve of the sample to be tested.

2. The asphalt UV-visible absorption spectrum testing method based on an integrating sphere according to claim 1, characterized in that: In step A and step C, the volume ratio of n-heptane to toluene in the n-heptane-toluene mixture is 60-150:

1.

3. The asphalt UV-visible absorption spectrum testing method based on integrating sphere according to claim 2, characterized in that: In step A, the concentration of asphalt in the n-heptane-toluene mixture is 0.2-2.0 mg / mL; in step B, the concentration of BaSO4 added in the n-heptane-toluene mixture is 2-18 mg / mL; the mass ratio of asphalt to BaSO4 is 1:9-19.

4. The asphalt UV-visible absorption spectrum testing method based on an integrating sphere according to claim 3, characterized in that: The asphalt is road petroleum asphalt, including base asphalt of various grades, SBS modified asphalt, rubber modified asphalt, and SBS-rubber composite modified asphalt.

Images