A monitoring method for the aging degree of in-service SBS modified asphalt pavement

Abstract

The present invention discloses a method for monitoring the aging degree of in-service SBS modified asphalt pavement, which includes the following steps: (1) Conduct a simulated aging test on the SBS modified asphalt used for paving the road surface, conduct a force-elongation test and a Fourier transform infrared spectroscopy test on the SBS modified asphalt with different aging times, establish a S BC relationship curve with A 1700 / 1600 , and calculate the S BC when it is 0, denoted as A 1700 / 1600 , denoted as A 0; (2) During the service process of the road surface, regularly drill core samples of the asphalt surface layer, extract and recover the in-service SBS modified asphalt from the upper and middle surface layers respectively, conduct a Fourier transform infrared spectroscopy test, and calculate the A 1700 / 1600 of the upper and middle surface layers respectively according to the infrared spectra; (3) Evaluate the aging degree of the in-service SBS modified asphalt pavement based on the relationship curve between S BC and A 1700 / 1600 . The present invention provides a method for monitoring the aging degree of in-service SBS modified asphalt pavement, which can provide a basis and tool for the decision-making of the maintenance timing and maintenance plan of SBS modified asphalt pavement.

Description

Technical Field

[0001] The present invention relates to the technical field of road engineering, and discloses a method for monitoring the aging degree of in-service SBS modified asphalt pavement. Background Art

[0002] Due to the excellent performance of SBS modified asphalt, it has now been widely used in the upper and middle layers of asphalt pavements of high-grade highways and urban arterial roads in China. During the service process of SBS modified asphalt pavement, due to severe climatic conditions and traffic conditions, SBS modified asphalt is bound to age. The aging mechanism is that SBS degrades, the asphaltene content increases, and the light component content decreases, which is manifested as the decline of the performance of SBS modified asphalt, and then develops into various damages on the pavement. Therefore, monitoring the performance of SBS modified asphalt pavement and, when the SBS modified asphalt ages to a certain extent and the service performance and its attenuation rate of the SBS modified asphalt pavement are at a certain level, adopting appropriate solutions for timely maintenance and repair is of great significance for extending the pavement life and improving the pavement service quality.

[0003] The invention patent with the application number 201710303780.0 discloses a method for in-situ discrimination of asphalt aging degree based on atomic force microscopy technology, and gives a method for directly discriminating the asphalt aging degree. The macroscopic and microscopic indexes adopted cannot reflect the SBS degradation characteristics, so it is only applicable to matrix asphalt and not applicable to the evaluation of the aging degree of SBS modified asphalt. In addition, this patent is applicable to obtaining the instantaneous aging characteristics of asphalt, without grading the aging degree of asphalt. Due to the lack of a long-term decay curve of macroscopic properties, it is also impossible to continuously monitor the asphalt aging characteristics, and no appropriate maintenance method corresponding to the aging asphalt characteristics is provided. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method for monitoring the aging degree of in-service SBS modified asphalt pavement. The solution provided by the present invention is as follows:

[0005] A method for monitoring the aging degree of in-service SBS modified asphalt pavement includes the following steps:

[0006] (1) Conduct a simulated aging test on the SBS modified asphalt used for paving the road surface, conduct a force-elongation test and a Fourier transform infrared spectroscopy test on the SBS modified asphalt with different aging times, calculate the toughness index value (S BC ) and the ratio (A -1 ) of the absorbance at 1700 cm -1 and 1600 cm 1700 / 1600 ) of the infrared spectrum of the SBS modified asphalt with different aging times, and establish the relationship between S BC and A 1700 / 1600Relationship curve, and calculate S of SBS modified asphalt according to the curve relationship BC A when it is 0 1700 / 1600 , denoted as A0;

[0007] (2) During the service process of the road surface, regularly drill core samples of the asphalt surface layer, cut the core samples according to the layer position to obtain the upper and middle layer core samples, separately extract and recover the in-service SBS modified asphalt in the upper and middle layers, conduct Fourier transform infrared spectroscopy tests, and calculate the A of the upper and middle layers respectively according to the infrared spectra 1700 / 1600 .

[0008] (3) According to the relationship curve between S BC and A 1700 / 1600 , evaluate the aging degree of the in-service SBS modified asphalt pavement, and adopt different maintenance methods for SBS modified asphalt pavements with different aging degrees.

[0009] The method for monitoring the aging degree of the in-service SBS modified asphalt pavement as described above is characterized in that the test temperature of the force ductility test in (1) is 10°C.

[0010] The method for monitoring the aging degree of the in-service SBS modified asphalt pavement as described above is characterized in that the relationship curve between S BC and A 1700 / 1600 in (1) is fitted with a quadratic polynomial, calculate the solution of the quadratic polynomial when S BC =0, and take the solution with the smaller value as A0.

[0011] The method for monitoring the aging degree of the in-service SBS modified asphalt pavement as described above is characterized in that the aging degree in (3) is divided according to S BC and A 1700 / 1600 of the upper and middle layers:

[0012]

[0013] In the formula, A 上 is the A of the recovered SBS modified asphalt in the upper layer 1700 / 1600 ; A 中 is the A of the recovered SBS modified asphalt in the middle layer 1700 / 1600 ; The mild aging is further divided into:

[0014]

[0015] The described method for monitoring the aging degree of in-service SBS modified asphalt pavement is characterized in that the maintenance method in (3) is determined according to the aging degree: for mild level 1, local repair can be carried out according to the pavement structure performance and functional status, or no maintenance is required; for mild level 2, preventive maintenance methods such as paving a micro-surface should be adopted; for moderate aging, in-situ hot recycling maintenance of the upper surface layer should be adopted; for severe aging, plant-mixed hot recycling maintenance after milling the upper and middle surface layers should be adopted.

[0016] Beneficial effects:

[0017] The present invention combines macroscopic indicators and microscopic compositions to evaluate the aging degree of SBS modified asphalt. The toughness index based on the force-elongation and the ratio of the absorbance at 1700 cm -1 and 1600 cm -1 of the Fourier transform infrared spectrum can both well reflect the degradation degree of SBS in SBS modified asphalt, while the existing evaluation methods only consider the changes in asphalt components. In addition, by comprehensively considering the degradation degrees of SBS modified asphalt in the upper and middle surface layers to evaluate the pavement aging degree, the accuracy, reliability and effectiveness of the evaluation of the aging degree of modified asphalt pavement are improved.

[0018] The present invention provides a method for monitoring the aging degree of in-service SBS modified asphalt pavement, which is applicable to the whole-process performance monitoring during the operation period of SBS modified asphalt pavement, and can provide a basis and technical tool for the decision-making of the maintenance time and maintenance plan of SBS modified asphalt pavement. Brief description of the drawings

[0019] Figure 1 It is the relationship curve between I-D type linear SBS modified asphalt S BC and A 1700 / 1600 Specific embodiments

[0020] The present invention provides a method for monitoring the aging degree of in-service SBS modified asphalt pavement.

[0021] The embodiments described herein are specific specific embodiments of the present invention, which are used to illustrate the concept of the present invention and are exemplary, not limiting the embodiments and scope of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the patent claims and specifications of the present application, and these technical solutions include technical solutions that make any obvious substitutions and modifications to the embodiments described herein.

[0022] ​The sources of some raw materials used in the following examples are as follows: The SBS modified asphalt is I-D type linear SBS modified asphalt; The in-service SBS modified asphalt pavement is an asphalt pavement of a certain expressway in Anhui Province. The I-D type linear SBS modified asphalt is used for both the surface course and the middle course.

[0023] Example

[0024] (1) Conduct TFOT simulated aging tests on I-D type linear SBS modified asphalt with an aging time interval of 6 h and a total duration of 48 h. Conduct 10°C force-ductility tests and Fourier transform infrared spectroscopy tests on the SBS modified asphalt at different aging times, and calculate the toughness index values (S BC ) and the ratio of absorbance at 1700 cm -1 and 1600 cm -1 in the infrared spectrum (A 1700 / 1600 ). Use a quadratic polynomial to fit the relationship between S BC and A 1700 / 1600 . The fitting results and curves are as shown in Figure 1 . Solve the quadratic polynomial to obtain the solutions 0.27645 and 0.50092 respectively. Then, when S BC is 0, A0 is 0.27645.

[0025] (2) Drill core samples from the asphalt surface layer of the SBS modified asphalt pavement of a certain expressway in Anhui Province, and cut the core samples according to the layer position to obtain the surface course and the middle course of the SBS modified asphalt. First, place the core samples of the surface course and the middle course of the SBS modified asphalt in an oven at 135°C for 1 h respectively, then disperse the core samples of the surface course and the middle course and place them at room temperature for 2 h respectively. Finally, recover the SBS modified asphalt in the core samples using a Soxhlet extractor and a rotary evaporator respectively, and conduct infrared spectrum tests on the recovered SBS modified asphalt. Calculate the value of A 上 to be 0.21 and the value of A 中 to be 0.15 according to the infrared spectrum.

[0026] (3) It can be seen that A 上 < A0 indicates mild aging. Further calculate to be mild level 1. After investigation, the structural performance and functionality of the pavement are both good, and maintenance can be not carried out.

Claims

1. A method for monitoring the aging degree of in-service SBS modified asphalt pavement, characterized in that, It includes the following steps: (1) A simulated aging test was conducted on the SBS modified asphalt used for pavement paving. The force ductility test and Fourier transform infrared spectroscopy test were conducted on the SBS modified asphalt with different aging times. The toughness index value S of the SBS modified asphalt with different aging times was calculated. BC and infrared spectrum 1700cm -1 With 1600cm -1 The ratio of the absorbance at 1700 / 1600 , establish S BC With A 1700 / 1600 The relationship curve of SBS modified asphalt S is calculated based on the relationship of the curve. BC A when it is 0 1700 / 1600 , denoted as A0; (2) During the service process of the road surface, core samples of the asphalt surface layer are regularly drilled, and the core samples are cut by layer to obtain core samples of the upper and middle surface layers. The in-service SBS modified asphalt of the upper and middle surface layers is extracted and recovered respectively, and Fourier transform infrared spectroscopy tests are carried out. The A values of the upper and middle surface layers are calculated respectively according to the infrared spectra. 1700 / 1600 ; (3) Based on S BC and A 1700 / 1600 relation curve, evaluate the aging degree of the in-service SBS modified asphalt pavement, so as to adopt different maintenance methods for SBS modified asphalt pavements with different aging degrees; In step (3), the aging degree is divided according to S of the upper and middle surface layers BC and A 1700 / 1600 as follows: where A 上 is the A of the recycled SBS modified asphalt in the upper layer 1700 / 1600 ; A 中 is the A of the recycled SBS modified asphalt in the middle layer 1700 / 1600 ; Mild aging is further divided into:

2. The method for monitoring the aging degree of in-service SBS modified asphalt pavement according to claim 1, wherein, In step (1), the test temperature of the ductility test is 10°C.

3. The method for monitoring the aging degree of in-service SBS modified asphalt pavement according to claim 1, wherein, In step (1), S BC and A 1700 / 1600 relation curve, use a quadratic polynomial for fitting, calculate S BC = 0, the solution of the quadratic polynomial is taken, and the solution with the smaller value is A0.

4. The in-service SBS modified asphalt pavement aging degree monitoring method according to claim 1, characterized in that, In step (3), the curing method is determined according to the degree of aging: for mild level 1, local repair is carried out according to the pavement structure performance and functional status or no curing is carried out; for mild level 2, a preventive curing method of adding a micro-surfacing is adopted; for moderate aging, an in-situ hot recycling curing method for the upper surface layer is adopted; for severe aging, a plant-mixed hot recycling curing method after milling the upper and middle surface layers is adopted.

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