An evaluation method for the fusion degree of recycled asphalt mortar

Abstract

The present invention discloses a method for evaluating the degree of fusion of regenerated asphalt mortar, comprising the following steps: S1, obtaining force-displacement curves of asphalt mortar calibration specimens with different old asphalt mixing ratios, and calculating the interface failure energy of the corresponding calibration specimens based on the force-displacement curves; S2, fitting a regression equation for the interface failure energy and the degree of fusion; S3, obtaining the force-displacement curves of the regenerated asphalt specimens to be evaluated and calculating the interface failure energy, and calculating the degree of fusion based on the fitted regression equation. The present invention determines the quantitative evaluation of the degree of fusion through a pull-out test, which can provide a basic database for reference of process parameters for the preparation of regenerated asphalt mortar. The interface failure energy is easy to obtain, and the evaluation method can be reused for the same raw material. Moreover, the fusion effect of the entire fine material in the mortar can be evaluated rather than a local evaluation.

Description

Technical Field

[0001] The present invention relates to a method for evaluating the fusion degree of regenerated asphalt mortar, and belongs to the field of detection and evaluation of basic physical properties of regenerated asphalt and asphalt mixture. Background Art

[0002] Currently, the most researched topic is the evaluation of the fusion of new and old asphalt in recycled asphalt mixtures. For example, the patent entitled "A method and system for determining the degree of fusion of recycled asphalt mixtures" (application number CN202010429978.5) describes a method for determining the degree of fusion of new and old asphalt in recycled asphalt mixtures. The method includes extracting the old asphalt from the recycled asphalt mixture sample, mixing the old asphalt with the new asphalt in different proportions to obtain multiple calibration specimens; performing fluorescence microscopy analysis on the calibration specimens to obtain a calibration fluorescence intensity; using a linear fitting method and the calibration fluorescence intensity to obtain a regression equation for the degree of fusion; performing layered peeling on the recycled asphalt mixture to be tested to obtain a test specimen; using the test fluorescence intensity of the test specimen and the regression equation for the degree of fusion to obtain the fusion of new and old asphalt in the recycled asphalt mixture to be tested. This invention, by combining the fluorescence microscopy analysis method with the layered peeling method, can conveniently and effectively analyze the fusion of new and old asphalt in the recycled asphalt mixture from a microscopic perspective and determine the fusion effect of the regeneration process on the new and old asphalt. However, the observation equipment for fluorescence microscopy analysis is expensive, the analysis method is complex, the detection cost is high, and it can only observe the local degree of fusion of new and old asphalt. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for evaluating the fusion degree of regenerated asphalt mortar. The quantitative evaluation of the fusion degree determined by the pull-out test can provide a basic database for reference of the process parameters for the preparation of regenerated asphalt mortar. The interface failure energy can be easily obtained, the evaluation method for the same raw material can be reused, and the fusion effect of the overall fine material in the mortar can be evaluated rather than a local evaluation.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A method for evaluating the fusion degree of recycled asphalt mortar comprises the following steps:

[0006] S1. Obtain force-displacement curves of asphalt mortar calibration specimens with different old asphalt mixing ratios, and calculate the interface failure energy of the corresponding calibration specimens based on the force-displacement curves;

[0007] S2, fitting the regression equation of interface failure energy and fusion degree;

[0008] S3. Obtain the force-displacement curve of the recycled asphalt specimen to be evaluated and calculate the interface failure energy, and calculate the degree of fusion based on the fitted regression equation.

[0009] Preferably, the calculation method of the interface failure energy of the asphalt mortar calibration specimen is: the interface failure energy is obtained by integrating the force-displacement curve using the following formula:

[0010] ,

[0011] Where E is the interfacial failure energy of the asphalt mortar calibration specimen, in J; a and b are the starting and ending points of the force on the force-displacement curve, in N; f(x) is the force-displacement curve of each asphalt mortar calibration specimen.

[0012] Preferably, the regression equation of the interfacial failure energy and fusion degree of the regenerated asphalt specimen to be evaluated is fitted using a sigmoidal model, and the regression equation is as follows:

[0013] ,

[0014] Where: y is the interfacial failure energy of the recycled asphalt specimen to be evaluated, unit: J; x is the degree of integration, unit: %; A 1 、 A 2 、 x 0 、 d x is the fitting parameter.

[0015] Preferably, the preparation method of asphalt mortar calibration specimens with different old asphalt mixing ratios is: recover oil-rich RAP fines to obtain old asphalt and mineral powder; then fuse old asphalt with mineral powder and new asphalt in different ratios to obtain multiple groups of asphalt mortars, and prepare asphalt mortar calibration specimens of the same size after cooling.

[0016] Preferably, the specific preparation method of the recycled asphalt specimen to be evaluated is: obtain oil-rich RAP fine material, then fuse the oil-rich RAP fine material with new asphalt to obtain asphalt mortar and then filter out the asphalt mortar. After the asphalt mortar is cooled, prepare the recycled asphalt specimen to be evaluated with the same size as the asphalt mortar calibration specimen.

[0017] Preferably, the specific method for recovering the oil-rich RAP fine material and obtaining the old asphalt and mineral powder is as follows: the oil-rich RAP fine material obtained from the asphalt pavement after milling is immersed in the extraction liquid for at least 1 hour and then extracted, the extract is dried to obtain the old asphalt, and the residual fine material is dried and sieved to obtain the mineral powder.

[0018] Preferably, a drying step is performed after the oil-rich RAP fines are recovered.

[0019] Preferably, the particle size of the oil-rich RAP fines is ≤5 mm.

[0020] Preferably, the specific preparation method of the asphalt mortar is: mixing old asphalt and / or mineral powder with new asphalt, and stirring at 100-200° C. for 3-60 minutes;

[0021] Among them, the amount of old asphalt added is 0-100% of the total amount of old asphalt obtained after drying the extract, the amount of mineral powder added is the total amount of mineral powder obtained by drying and screening the residual fine material, and the mass ratio of the amount of new asphalt to the initially obtained oil-rich RAP fine material is 1:1.

[0022] Preferably, the specific preparation method of the asphalt mortar is as follows: the oil-rich RAP fine material is blended with the new asphalt, and stirred at 100-200° C. for 3-60 min;

[0023] Among them, the mass ratio of oil-rich RAP fines to new asphalt is 1:1.

[0024] The beneficial effects of the present invention are:

[0025] Compared with the existing method for evaluating the degree of fusion between new and old asphalt, the present invention uses simple equipment, easily available test materials, and a simple and convenient process. The quantitative evaluation of the degree of fusion determined by the pull-out test can provide a basic database for reference of process parameters for the preparation of recycled asphalt mortar. The interface damage energy can be easily obtained, and the evaluation method for the same raw material can be reused. The advantage of the present invention is that it can evaluate the fusion effect of the entire oil-rich RAP fine material in the mortar rather than a local evaluation. Moreover, this scheme can also be used to evaluate the degree of fusion of non-oil-rich RAP fine material recycled asphalt mortar, and has a wide range of applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the interface destruction energy-fusion degree calibration curve. DETAILED DESCRIPTION

[0027] The present invention provides a method for evaluating the fusion degree of regenerated asphalt mortar, comprising the following steps:

[0028] (1) Obtaining oil-rich RAP fines and drying them in an oven;

[0029] (2) recovering the oil-rich RAP fines in step (1) using the Absen process to obtain old asphalt and mineral powder;

[0030] (3) Mix different proportions of old asphalt with mineral powder and new asphalt to represent different degrees of fusion, stir to ensure sufficient mixing, and then make multiple asphalt mortar calibration specimens (of the same size);

[0031] (4) Conduct a pull-out test on the asphalt mortar calibration specimen to obtain the force-displacement curve of each calibration specimen, and integrate the curve using formula (1) to obtain the interface failure energy E of each calibration specimen;

[0032] (1),

[0033] Where, E is the interface failure energy of the asphalt mortar calibration specimen, unit is J; a and b are the starting and ending points of the force value on the force-displacement curve (X axis), unit is N; f(x) is the force-displacement curve of each specimen pulling;

[0034] (5) Using the sigmoidal model (Equation (2)), the regression equation of the interfacial failure energy and fusion degree of the recycled asphalt specimen to be evaluated was obtained;

[0035] (2),

[0036] Where y is the interfacial failure energy of the recycled asphalt specimen to be evaluated, unit: J; x is the degree of integration, unit: %; A 1 、 A 2 、 x 0 、 d x is the fitting parameter;

[0037] (6) obtaining oil-rich RAP fines and uniformly mixing them with new asphalt in a mass ratio of 1:1 to prepare recycled asphalt mortar;

[0038] (7) Use a wire mesh with a sieve size of 0.075 mm to filter out the asphalt mortar in the recycled asphalt mortar. Take part of the asphalt mortar to prepare the recycled asphalt specimen to be evaluated (the size is the same as the asphalt mortar calibration specimen) and perform a pull-out test to calculate the interface failure energy. The degree of fusion in the asphalt mortar is calculated by regression equation with the calibration value. The higher the degree of fusion, the lower the interface failure energy.

[0039] The oil-rich RAP fine material in step (1) and step (6) is obtained by fine separation after milling of asphalt pavement, and has a particle size of ≤3 mm.

[0040] In step (2), the specific method for obtaining the old asphalt and mineral powder is: fully immerse the oil-rich RAP fine material treated in step (1) in the extraction liquid for more than 1 hour (the same immersion time is used when preparing different asphalt mortar calibration specimens) to loosen the clumps and fully dissolve the old asphalt, and then transfer all the materials in the container to the extraction instrument for extraction; dry the extract to obtain the old asphalt, and dry and sieve the remaining fine material to obtain the mineral powder.

[0041] In step (3), the old asphalt obtained in step (2) is mixed with new asphalt and mineral powder in different proportions, stirred at 130°C to 160°C to fully blend the new and old asphalts, and then a plurality of asphalt mortar calibration specimens are prepared.

[0042] In the above technical solution, all the old asphalt is in the oil-rich RAP fines before preparing the recycled asphalt mortar. During the mortar preparation process, the old asphalt migrates and gradually merges with the new asphalt from the surface of the fines into the asphalt mortar. Different mixing ratios of new and old asphalt indicate different degrees of fusion. The integration of old asphalt will reduce the interfacial destruction energy in the pull-out test. Therefore, the proportion of fused asphalt in the asphalt mortar and the proportion of unfused old asphalt in the oil-rich RAP fines can be calculated through the calibration curve.

[0043] In the following embodiments, the method for obtaining the interface damage energy-fusion degree calibration curve is specifically as follows:

[0044] Five portions of oil-rich RAP fine material totaling 1500 g were obtained and placed in an oven for drying; the old asphalt and mineral powder in the oil-rich RAP fine material were extracted using the Absen method to obtain 107.31 g of old asphalt and 293.61 g of mineral powder. On average, 21.462 g of old asphalt and 58.722 g of mineral powder were obtained in each portion (300 g) of oil-rich RAP fine material.

[0045] The old asphalt was divided into 5 parts, namely 20%, 40%, 60%, 80% and 100% of 21.462g respectively, and then mixed with 58.722g of mineral powder and 300g of new asphalt respectively, and stirred at 160℃ for 10min to allow the new and old asphalt to merge and mix evenly with the mineral powder to produce 5 types of asphalt mortars; then 58.722g of mineral powder and 300g of new asphalt were mixed, and stirred at 160℃ for 10min to allow the new asphalt and mineral powder to mix evenly to produce the 6th asphalt mortar without old asphalt.

[0046] After the six asphalt mortars were cooled, multiple groups of calibration specimens with different old asphalt contents were prepared (10 calibration specimens in each group, with a single calibration specimen weight of 0.5 g). Pull-out tests were performed on multiple calibration specimens in each group to calculate the average value. The pull-out force-displacement curve was calculated according to the formula The interface failure energy is obtained by integration, and then the sigmoidal model is used to fit the regression equation of the interface failure energy and fusion degree of the recycled asphalt specimen to be evaluated:

[0047] ,

[0048] Where y is the interfacial failure energy of the recycled asphalt specimen to be evaluated, J, and the numerical value can be used in the calculation; x is the degree of integration, %; A 1 、 A 2 、 x 0 、 d x is the fitting parameter. A 1=77.9266, A 2 =1.18594, x 0 =-159.68, d x =42.2553, the corresponding interface damage energy-fusion degree calibration curve is as follows Figure 1 .

[0049] Example 1: This example provides a method for evaluating the fusion degree of regenerated asphalt mortar, comprising the following steps:

[0050] (1) Obtain 500 g of oil-rich RAP fine material and dry it in an oven;

[0051] (2) The oil-rich RAP fine material in step (1) and the new asphalt were mixed uniformly in a mass ratio of 1:1, and stirred at 160° C. for 5 min to prepare a regenerated asphalt mortar;

[0052] (3) The asphalt mortar in the recycled asphalt mortar was filtered out using a wire mesh with a mesh size of 0.075 mm. After the asphalt mortar was cooled, samples were prepared according to the standard of the calibration specimen and a pull-out test was performed. The calculated interfacial failure energy was 1.55 J. The calibration value regression equation was used to calculate that the degree of fusion in the asphalt mortar was 66%.

[0053] Example 2: This example provides a method for evaluating the fusion degree of regenerated asphalt mortar, comprising the following steps:

[0054] (1) Obtain 500 g of oil-rich RAP fine material and dry it in an oven;

[0055] (2) The oil-rich RAP fine material in step (1) and the new asphalt were mixed uniformly in a mass ratio of 1:1, and stirred at 160° C. for 10 min to prepare a recycled asphalt mortar;

[0056] (3) The asphalt mortar in the recycled asphalt mortar was filtered out using a wire mesh with a mesh size of 0.075 mm. After the asphalt mortar was cooled, samples were prepared according to the standard of the calibration specimen and a pull-out test was performed. The calculated interfacial failure energy was 1.48 J. The calibration value regression equation was used to calculate that the degree of fusion in the asphalt mortar was 75%.

[0057] Example 3: This example provides a method for evaluating the fusion degree of regenerated asphalt mortar, comprising the following steps:

[0058] (1) Obtain 500 g of oil-rich RAP fine material and dry it in an oven;

[0059] (2) The oil-rich RAP fine material in step (1) and the new asphalt were mixed uniformly in a mass ratio of 1:1, and stirred at 160° C. for 15 min to prepare a recycled asphalt mortar;

[0060] (3) The asphalt mortar in the recycled asphalt mortar was filtered out using a wire mesh with a mesh size of 0.075 mm. After the asphalt mortar was cooled, samples were prepared according to the standard of the calibration specimen and a pull-out test was performed. The calculated interfacial failure energy was 1.40 J. The degree of fusion in the asphalt mortar was calculated to be 88% using the calibration value regression equation.

[0061] The above is only a preferred embodiment of the patent of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the patent of the present invention. These improvements and modifications should also be regarded as the scope of protection of the patent of the present invention.

Claims

1. A method for evaluating the fusion degree of recycled asphalt mortar, characterized in that: The steps include: S1. Obtain force-displacement curves of asphalt mortar calibration specimens with different old asphalt mixing ratios, and calculate the interface failure energy of the corresponding calibration specimens based on the force-displacement curves; S2, fitting the regression equation of interface failure energy and fusion degree; S3. Obtain the force-displacement curve of the recycled asphalt specimen to be evaluated and calculate the interface failure energy, and calculate the degree of fusion based on the fitted regression equation; The calculation method of the interface failure energy of the asphalt mortar calibration specimen is as follows: the interface failure energy is obtained by integrating the force-displacement curve using the following formula: ， Where, E is the interfacial failure energy of the asphalt mortar calibration specimen, unit is J; a and b are the starting and ending points of the force value on the force-displacement curve, unit is N; f(x) is the force-displacement curve of each asphalt mortar calibration specimen; The regression equation of the interfacial failure energy and fusion degree of the recycled asphalt specimen to be evaluated is fitted as follows: ， Where: y is the interfacial failure energy of the recycled asphalt specimen to be evaluated, unit: J; x is the degree of integration, unit: %; A 1 、 A 2 、 x 0 、 d x is the fitting parameter.

2. The method for evaluating the fusion degree of regenerated asphalt mortar according to claim 1, characterized in that: The preparation method of asphalt mortar calibration specimens with different old asphalt mixing ratios is as follows: recover oil-rich RAP fines to obtain old asphalt and mineral powder; then blend old asphalt with mineral powder and new asphalt in different ratios to obtain multiple groups of asphalt mortars, and prepare asphalt mortar calibration specimens of the same size after cooling.

3. The method for evaluating the fusion degree of regenerated asphalt mortar according to claim 1, characterized in that: The specific preparation method of the recycled asphalt specimen to be evaluated is: obtain oil-rich RAP fine material, then fuse the oil-rich RAP fine material with new asphalt to obtain asphalt mortar and then filter out the asphalt mortar. After the asphalt mortar is cooled, prepare the recycled asphalt specimen to be evaluated with the same size as the asphalt mortar calibration specimen.

4. The method for evaluating the fusion degree of regenerated asphalt mortar according to claim 2, characterized in that: The specific method for recovering oil-rich RAP fines to obtain old asphalt and mineral powder is as follows: immersing the oil-rich RAP fines obtained from asphalt pavement milling in an extraction liquid for at least 1 hour and then extracting, drying the extract to obtain old asphalt, and drying and sieving the remaining fines to obtain mineral powder.

5. The method for evaluating the fusion degree of regenerated asphalt mortar according to claim 2, characterized in that: After the oil-rich RAP fines are recovered, a drying step is also performed.

6. The method for evaluating the fusion degree of regenerated asphalt mortar according to claim 2 or 3, characterized in that: The particle size of oil-rich RAP fine material is ≤5mm.

7. The method for evaluating the fusion degree of regenerated asphalt mortar according to claim 2, characterized in that: The specific preparation method of asphalt mortar is as follows: mixing old asphalt and / or mineral powder with new asphalt, stirring at 100-200°C for 3-60 minutes; Among them, the amount of old asphalt added is 0-100% of the total amount of old asphalt obtained after drying the extract, the amount of mineral powder added is the total amount of mineral powder obtained by drying and screening the residual fine material, and the mass ratio of the amount of new asphalt to the initially obtained oil-rich RAP fine material is 1:

1.

8. The method for evaluating the fusion degree of regenerated asphalt mortar according to claim 3, characterized in that: The specific preparation method of asphalt mortar is as follows: the oil-rich RAP fines are mixed with new asphalt and stirred at 100-200°C for 3-60 minutes; Among them, the mass ratio of oil-rich RAP fines to new asphalt is 1:1.

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