Recycled asphalt mortar fusion degree evaluation method

Abstract

The invention discloses a recycled asphalt mortar fusion degree evaluation method which comprises the following steps: S1, acquiring a force value-displacement curve of an asphalt mortar calibration test piece with different old asphalt mixing proportions, and calculating interface failure energy of the corresponding calibration test piece according to the force value-displacement curve; s2, fitting a regression equation of the interface failure energy and the fusion degree; and S3, obtaining a force value-displacement curve of the to-be-evaluated regenerated asphalt test piece, calculating the interface failure energy, and calculating the fusion degree based on the fitted regression equation. According to the method, the fusion degree is determined through the pull-out test, quantitative evaluation can provide a reference basic database for technological parameters of recycled asphalt mortar preparation, interface damage can be easily obtained, the same raw material evaluation method can be repeatedly used, and the fusion effect of the whole fine material in the mortar can be evaluated instead of local evaluation.

Description

Technical Field

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

[0002] Currently, more research has been done on the evaluation of the fusion of new and old asphalt in recycled asphalt mixtures. For example, in the patent named "A Method and System for Determining the Fusion Degree of Recycled Asphalt Mixtures" (application number: CN202010429978.5), the determination method includes: extracting the old asphalt from the recycled asphalt mixture sample, mixing the old asphalt and the new asphalt in different proportions to obtain multiple calibration specimens; performing fluorescence microscopic analysis on the calibration specimens to obtain the calibration fluorescence intensity; using the linear fitting method and the calibration fluorescence intensity to obtain the regression equation of the fusion degree; performing layer-by-layer peeling on the recycled asphalt mixture to be detected to obtain the test specimens; and using the test fluorescence intensity of the test specimens and the regression equation of the fusion degree to obtain the fusion situation of the new asphalt and the old asphalt in the recycled asphalt mixture to be detected. By combining the fluorescence microscopic analysis method and the layer-by-layer peeling method, this invention can conveniently and effectively analyze the fusion situation of new and old asphalt in recycled asphalt mixtures from the microscopic level and determine the fusion effect of the recycled process on new and old asphalt. However, fluorescence microscopic analysis has expensive observation equipment, complex analysis methods, high detection costs, and can only observe the local fusion degree 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 recycled asphalt mortar. By determining the quantitative evaluation of the fusion degree through the pull-out test, a basic database that can provide reference for the process parameters of preparing recycled asphalt mortar can be obtained. The interfacial failure energy is easy to obtain, the evaluation method can be reused for the same raw materials, and the fusion effect of the overall fine materials in the mortar can be evaluated rather than a local evaluation.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A method for evaluating the fusion degree of recycled asphalt mortar, comprising the following steps: S1. Obtain the force-displacement curves of the asphalt mortar calibration specimens with different mixing ratios of old asphalt, and calculate the interfacial failure energy of the corresponding calibration specimens according to the force-displacement curves; S2. Fit the regression equation between the interfacial failure energy and the fusion degree; S3. Obtain the force-displacement curve of the recycled asphalt specimen to be evaluated and calculate the interfacial failure energy, and calculate the fusion degree based on the fitted regression equation.

[0005] Preferably, the calculation method of the interfacial failure energy of the asphalt mortar calibration specimen is: integrating the force-displacement curve using the following formula to obtain the interfacial failure energy, , wherein, E is the interfacial failure energy of the calibrated specimen of asphalt mortar, with the unit of J; a and b are the starting and ending points of the force value on the force value-displacement curve, with the unit of N; f(x) is the force value-displacement curve of the pull-out of each calibrated specimen of asphalt mortar.

[0006] Preferably, the regression equation of the interfacial failure energy and the fusion degree of the recycled asphalt specimen to be evaluated is fitted by the sigmoidal model, and the regression equation is as follows: , wherein: y is the interfacial failure energy of the recycled asphalt specimen to be evaluated, with the unit of J; x is the fusion degree, with the unit of %; A 1 , A 2 , x 0 , d x are fitting parameters.

[0007] Preferably, the preparation method of the calibrated specimens of asphalt mortar with different old asphalt mixing ratios is: recover the rich-oil RAP fine material to obtain old asphalt and mineral powder; then fuse different proportions of old asphalt with mineral powder and new asphalt to obtain multiple groups of asphalt mortar, and prepare calibrated specimens of asphalt mortar with the same size after cooling.

[0008] Preferably, the specific preparation method of the recycled asphalt specimen to be evaluated is: obtain the rich-oil RAP fine material, then fuse the rich-oil RAP fine material with new asphalt, filter out the asphalt mortar after obtaining the asphalt mortar, and prepare the recycled asphalt specimen to be evaluated with the same size as the calibrated specimen of asphalt mortar after the asphalt mortar cools.

[0009] Preferably, the specific method for recovering the rich-oil RAP fine material to obtain old asphalt and mineral powder is: immerse the rich-oil RAP fine material taken from the milled asphalt pavement in the extraction liquid for at least 1 h and then carry out extraction, dry the extraction liquid to obtain old asphalt, and dry and screen the residual fine material to obtain mineral powder.

[0010] Preferably, a drying step is also carried out after recovering the rich-oil RAP fine material.

[0011] Preferably, the particle size of the rich-oil RAP fine material ≤ 5 mm.

[0012] Preferably, the specific preparation method of the asphalt mortar is: mix old asphalt and / or mineral powder with new asphalt, and stir at 100 - 200 °C for 3 - 60 min; Among them, the addition amount of the old asphalt is 0-100% of the total amount of the old asphalt obtained after drying the extraction liquid, the addition amount of the mineral powder is the total amount of the mineral powder obtained by drying and screening the residual fine materials, and the mass ratio of the new asphalt to the rich-oil RAP fine materials obtained initially is 1:1.

[0013] Preferably, the specific preparation method of the asphalt mortar is as follows: fuse the rich-oil RAP fine materials with the new asphalt and stir at 100-200 °C for 3-60 min; Among them, the mass ratio of the rich-oil RAP fine materials to the new asphalt is 1:1.

[0014] The beneficial effects of the present invention are as follows: Compared with the existing evaluation methods for the fusion degree of new and old asphalts, the equipment used in the present invention is simple, the test materials are easy to obtain, and the process is simple and convenient. Determining the quantitative evaluation of the fusion degree through the pull-out test can provide a reference basic database for the process parameters of the preparation of recycled asphalt mortar. The interfacial fracture energy is easy to obtain, and the evaluation method for the same raw materials can be reused. The advantages of the present invention also lie in that it can evaluate the fusion effect of the overall rich-oil RAP fine materials in the mortar rather than a local evaluation, and this scheme can also be used for the evaluation of the fusion degree of recycled asphalt mortar of non-rich-oil RAP fine materials, with wide applicability. Description of the Drawings

[0015] Figure 1 It is a calibration curve of interfacial fracture energy - fusion degree. Detailed Embodiments

[0016] The present invention provides an evaluation method for the fusion degree of recycled asphalt mortar, including the following steps: (1) Obtain rich-oil RAP fine materials and place them in an oven for drying; (2) Recover the rich-oil RAP fine materials in step (1) by the Abson method to obtain old asphalt and mineral powder; (3) Mix different proportions of old asphalt, mineral powder, and new asphalt to characterize different fusion degrees, stir to ensure full mixing, and then make multiple asphalt mortar calibration specimens (with the same size); (4) Conduct a pull-out test on the asphalt mortar calibration specimens to obtain the force-displacement curve of each calibration specimen, and integrate the curve through formula (1) to obtain the interfacial fracture energy E of each calibration specimen; (1), In the formula, E is the interfacial fracture energy of the asphalt mortar calibration specimen, with the unit J; a and b are the starting and ending points of the force value on the force-displacement curve (X-axis), with the unit N; f(x) is the force-displacement curve of the pull-out of each specimen; (5) Use the sigmoidal model (formula (2)) to fit to obtain the regression equation of the interfacial fracture energy and the fusion degree of the recycled asphalt specimen to be evaluated; (2), where y is the interfacial failure energy of the recycled asphalt specimen to be evaluated, with the unit of J; x is the degree of fusion, with the unit of %; A 1 , A 2 , x 0 , d x are fitting parameters; (6) Obtain rich-oil RAP fines, and mix them with new asphalt evenly at a mass ratio of 1:1 to prepare recycled asphalt mortar; (7) Filter out the asphalt mortar in the recycled asphalt mortar with a wire mesh sieve with a mesh size of 0.075 mm. Take part of the asphalt mortar to prepare the recycled asphalt specimen to be evaluated (with the same size as the calibrated specimen of the asphalt mortar) and conduct a pull-out test to calculate the interfacial failure energy. Calculate the degree of fusion in the asphalt mortar by regression with the calibration value regression equation. The higher the degree of fusion, the lower the interfacial failure energy.

[0017] Among them, the rich-oil RAP fines in step (1) and step (6) are obtained by fine separation after milling the asphalt pavement, and the particle size is ≤ 3 mm.

[0018] In step (2), the specific methods for obtaining the old asphalt and mineral powder are as follows: fully immerse the rich-oil RAP fines treated in step (1) in the extraction liquid, soak for more than 1 h (the same soaking time is used when preparing different calibrated specimens of asphalt mortar) to loosen the agglomerates therein, dissolve the old asphalt fully, and then transfer all the substances in the container to a Soxhlet extractor for extraction; dry the extract to obtain the old asphalt, and dry and screen the remaining fines to obtain the mineral powder.

[0019] In step (3), the old asphalt obtained in step (2) is mixed with new asphalt and mineral powder in different proportions, and stirred at 130 °C to 160 °C to make the new and old asphalts fully fused, and then multiple calibrated specimens of asphalt mortar are made.

[0020] In the above technical solution, all the old asphalt is in the rich-oil RAP fines before preparing the recycled asphalt mortar. During the preparation of the mortar, the old asphalt migrates and gradually fuses with the new asphalt and enters the asphalt mortar from the surface of the fines. Different mixing ratios of new and old asphalts represent different degrees of fusion, and the incorporation of the old asphalt will reduce the interfacial failure energy in the pull-out test. Therefore, the proportion of the fused asphalt in the asphalt mortar and the proportion of the unfused old asphalt in the rich-oil RAP fines can be calculated through the calibration curve.

[0021] In the following examples, the specific method for obtaining the interfacial failure energy - degree of fusion calibration curve is as follows: Obtain 5 portions of 1500 g of rich-oil RAP fine materials and place them in an oven for drying; adopt the Abson method to extract and recover the old asphalt and mineral powder in the rich-oil RAP fine materials, obtaining 107.31 g of old asphalt and 293.61 g of mineral powder. On average, each portion (300 g) of rich-oil RAP fine materials yields 21.462 g of old asphalt and 58.722 g of mineral powder.

[0022] Divide the old asphalt into 5 portions, which are 20%, 40%, 60%, 80%, and 100% of 21.462 g respectively, and then mix them with 58.722 g of mineral powder and 300 g of new asphalt respectively. Stir at 160 °C for 10 min to make the old and new asphalt blend and mix evenly with the mineral powder, producing 5 kinds of asphalt mastics; then mix 58.722 g of mineral powder and 300 g of new asphalt, and stir at 160 °C for 10 min to make the new asphalt mix evenly with the mineral powder, producing the 6th kind of asphalt mastic without old asphalt.

[0023] After the 6 kinds of asphalt mastics are cooled, prepare multiple groups of calibration specimens with different old asphalt contents (10 calibration specimens in each group, and the mass of a single calibration specimen is 0.5 g). Conduct a pull-out test on multiple calibration specimens in each group and calculate the average value. Integrate the pull-out force value-displacement curve according to the formula to obtain the interfacial failure energy, and then use the sigmoidal model to fit to obtain the regression equation of the interfacial failure energy and the fusion degree of the regenerated asphalt specimens to be evaluated: , where y is the interfacial failure energy of the regenerated asphalt specimens to be evaluated, in J, and just take the numerical value during calculation; x is the fusion degree, in %; A 1 , A 2 , x 0 , d x are fitting parameters. In this fitting A 1 = 77.9266, A 2 = 1.18594, x 0 = -159.68, d x = 42.2553, and the corresponding interfacial failure energy-fusion degree calibration curve is as shown in Figure 1 .

[0024] Example 1: This example provides a method for evaluating the fusion degree of regenerated asphalt mortar, including the following steps: (1) Obtain 500 g of rich-oil RAP fine materials and place them in an oven for drying; (2) Mix the rich-oil RAP fines in step (1) and new asphalt evenly at a mass ratio of 1:1, and stir for 5 min at 160 °C to prepare the recycled asphalt mortar; (3) Filter out the asphalt mortar in the recycled asphalt mortar with a wire mesh with a sieve hole of 0.075 mm. After the asphalt mortar cools, make specimens according to the standard of the calibrated specimens and conduct a pull-out test. The calculated interfacial fracture energy is 1.55 J, and the degree of fusion in the asphalt mortar is calculated to be 66% using the calibration value regression equation.

[0025] Example 2: This example provides a method for evaluating the degree of fusion of recycled asphalt mortar, including the following steps: (1) Obtain 500 g of rich-oil RAP fines and place them in an oven for drying; (2) Mix the rich-oil RAP fines in step (1) and new asphalt evenly at a mass ratio of 1:1, and stir for 10 min at 160 °C to prepare the recycled asphalt mortar; (3) Filter out the asphalt mortar in the recycled asphalt mortar with a wire mesh with a sieve hole of 0.075 mm. After the asphalt mortar cools, make specimens according to the standard of the calibrated specimens and conduct a pull-out test. The calculated interfacial fracture energy is 1.48 J, and the degree of fusion in the asphalt mortar is calculated to be 75% using the calibration value regression equation.

[0026] Example 3: This example provides a method for evaluating the degree of fusion of recycled asphalt mortar, including the following steps: (1) Obtain 500 g of rich-oil RAP fines and place them in an oven for drying; (2) Mix the rich-oil RAP fines in step (1) and new asphalt evenly at a mass ratio of 1:1, and stir for 15 min at 160 °C to prepare the recycled asphalt mortar; (3) Filter out the asphalt mortar in the recycled asphalt mortar with a wire mesh with a sieve hole of 0.075 mm. After the asphalt mortar cools, make specimens according to the standard of the calibrated specimens and conduct a pull-out test. The calculated interfacial fracture energy is 1.40 J, and the degree of fusion in the asphalt mortar is calculated to be 88% using the calibration value regression equation.

[0027] The above are only the preferred embodiments of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention patent, several improvements and retouches can be made, and these improvements and retouches should also be regarded as the protection scope of the present invention patent.

Claims

1. A method for evaluating the fusion degree of recycled asphalt mortar, characterized in that: The steps include: S1. Obtain the 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 according to the force-displacement curves; S2, regression equation for fitting interface damage 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 then calculate the degree of fusion based on the fitted regression equation.

2. The method for evaluating the fusion degree of regenerated asphalt mortar according to claim 1, characterized in that the asphalt The calculation method of the interface failure energy of the glue calibration specimen is: 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 J; a and b are the starting and ending points of the force value on the force-displacement curve, unit N; f(x) is the force-displacement curve of each asphalt mortar calibration specimen.

3. The method for evaluating the fusion degree of regenerated asphalt mortar according to claim 2, characterized in that: The regression equation of the interface 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.

4. 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.

5. 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 mastic. After the asphalt mastic is cooled, prepare the recycled asphalt specimen to be evaluated with the same size as the asphalt mastic calibration specimen.

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

7. The method for evaluating the fusion degree of regenerated asphalt mortar according to claim 4 or 5, characterized in that: After the oil-rich RAP fines are recovered, a drying step is also performed.

8. The method for evaluating the fusion degree of regenerated asphalt mortar according to claim 4 or 5, characterized in that: The particle size of oil-rich RAP fine material is ≤5mm.

9. The method for evaluating the fusion degree of regenerated asphalt mortar according to claim 4, characterized in that: The specific preparation method of asphalt mortar is: mix old asphalt and / or mineral powder with new asphalt, and stir 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.

10. The method for evaluating the fusion degree of regenerated asphalt mortar according to claim 5, characterized in that: The specific preparation method of asphalt mortar is as follows: blend the oil-rich RAP fines with new asphalt and stir at 100-200°C for 3-60min; Among them, the mass ratio of oil-rich RAP fines to new asphalt is 1:1.

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