A method for evaluating the uniformity of asphalt film wrapping of asphalt mixture and workability

Abstract

The present application provides a kind of asphalt mixture and plasticity evaluation method based on asphalt film wrapping uniformity, comprising the following steps: step C100, asphalt mixture is stirred using asphalt mixture mixing machine;Step C200, the aggregate of maximum particle size in asphalt mixture is collected, is cut into sheet shape using resin fixation, is sprayed gold, and the asphalt film thickness wrapped on the surface of aggregate is scanned by SEM;Step C300, according to the scanned asphalt film thickness, propose the evaluation index of asphalt film wrapping uniformity;Step C400, asphalt mixture plasticity is evaluated using the evaluation index of asphalt film wrapping uniformity.The technical effects achieved: by a kind of asphalt mixture and plasticity evaluation method based on asphalt film wrapping uniformity of the present application, the mixing uniformity during mixing of asphalt mixture can be accurately evaluated, the asphalt mixture plasticity is quantified, and theoretical basis and data support are provided for later asphalt pavement performance evaluation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of asphalt mixture and workability evaluation, and particularly relates to an asphalt mixture and workability evaluation method based on asphalt film wrapping uniformity. BACKGROUND

[0002] Asphalt mixture and workability play a decisive role in the road performance of the asphalt pavement formed. The asphalt mixture with poor workability is not easy to pave and compact. The current asphalt mixture workability evaluation generally adopts the mixing torque method or the mixing current method. However, the mixing torque method for evaluating the asphalt mixture workability has some problems. The torque test value has large discreteness, and it is difficult to quantitatively analyze the asphalt mixture workability due to the influence of the overall rigidity of the instrument, the granularity of the asphalt mixture and the accuracy of the torque sensor. For the current test, the circuit voltage is related to the external input voltage during the mixing process, and the voltage at different times on the same day is different. It is not scientific and reasonable to evaluate the asphalt mixture workability by using a single current value to represent the mixing power. Therefore, it is of great significance to propose an asphalt mixture workability evaluation system to improve the performance of the asphalt pavement. SUMMARY

[0003] In view of the technical problem of inaccurate evaluation of the asphalt mixture workability by using the mixing torque method or the mixing current method in the prior art, the present application provides an asphalt mixture and workability evaluation method based on asphalt film wrapping uniformity, which can accurately evaluate the mixing uniformity of the asphalt mixture during the mixing process, quantitatively evaluate the asphalt mixture workability, and provide a theoretical basis and data support for the later asphalt performance evaluation.

[0004] To solve the technical problems in the prior art, the technical scheme adopted by the present application is as follows:

[0005] An asphalt mixture and workability evaluation method based on asphalt film wrapping uniformity, the steps are as follows:

[0006] Step C100. Stirring the asphalt mixture by using the asphalt mixture mixing machine;

[0007] Step C200. Collecting the aggregate with the maximum particle size in the asphalt mixture, fixing by using the resin, cutting into a sheet shape, spraying gold, and scanning the thickness of the asphalt film wrapped on the surface of the aggregate by using SEM;

[0008] Step C300. Proposing an asphalt film wrapping uniformity evaluation index according to the scanned asphalt film thickness;

[0009] Step C400. Evaluating the asphalt mixture and workability by using the asphalt film wrapping uniformity evaluation index.

[0010] As an improvement, the asphalt mixture in step C100 is stirred by an asphalt mixture mixer as follows: the aggregate and asphalt heated to a test temperature of 180 DEG C are respectively put into a stirring pot for mixing, the mixing time is 3 min, and the stirring speed is 80 r / min, thereby obtaining the asphalt mixture.

[0011] As an improvement, the aggregate with the maximum particle size in the asphalt mixture in step C200 is collected, fixed by resin, cut into a sheet, sprayed with gold, and the thickness of the asphalt film wrapped on the surface of the aggregate is scanned by SEM.

[0012] Step C210, after the asphalt mixture is mixed, a plurality of aggregate particles with the maximum particle size in the asphalt mixture are selected according to the gradation;

[0013] Step C220, the selected aggregate particle is poured into an asphalt segregation tube by using epoxy resin to form a cylinder, and the cylinder is placed for 24 h, and then the cured cylinder is taken out;

[0014] Step C230, the cured aggregate and resin are cut into a sheet with a thickness of 5 mm by using a cutting machine;

[0015] Step C240, the sheet containing the aggregate-asphalt-resin is put into a gold spraying device for gold spraying;

[0016] Step C250, the thickness of the asphalt film wrapped on the surface of the aggregate is scanned by using a SEM device.

[0017] As an improvement, the evaluation index of the uniformity of the asphalt film in step C300 is as follows:

[0018]

[0019] Wherein,

[0020] In the formula: CUAF is the evaluation index of the uniformity of the asphalt film, ATAF is the evaluation index of the average thickness of the asphalt film, mm, n is the number of aggregate particles with the maximum particle size in the asphalt mixture, AF1, AF2,..., AFn are the thicknesses of the asphalt films wrapped on the surfaces of the first-n aggregate particles, mm. n

[0021] Beneficial effects:

[0022] The asphalt mixture and workability evaluation method based on the uniformity of the asphalt film provided by the application can accurately evaluate the mixing uniformity in the mixing process of the asphalt mixture, quantize the workability of the asphalt mixture, and provide a theoretical basis and data support for the performance evaluation of the asphalt pavement in the later period. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 ​A flowchart of a method for evaluating the workability of asphalt mixtures based on the uniformity of asphalt film coating is provided in an embodiment of the present invention;

[0024] Figure 2 SEM scans of asphalt films in asphalt mixtures of different asphalt types (PG-64, PG-76), mixture types (AC-13, AC-20), and mixing temperatures (140℃, 180℃);

[0025] Figure 3 This is a graph showing the difference in average thickness of the asphalt film.

[0026] Figure 4 A diagram illustrating the uniformity of asphalt film coating. Detailed Implementation

[0027] The asphalt types used in the examples in this specification are PG-64 and PG-76, as shown in Table 1:

[0028] Table 1 Basic Performance Indicators of Asphalt

[0029]

[0030] The mixture types are AC-13 and AC-20, as shown in Table 2:

[0031] Table 2. Synthetic Gradation of the Mixture

[0032]

[0033] Example 1

[0034] like Figure 1 As shown in this embodiment, a method for evaluating the workability of asphalt mixtures based on the uniformity of asphalt film coating includes the following steps:

[0035] Step C100: Use an asphalt mixing planter to mix the asphalt mixture, specifically as follows: put the aggregate and asphalt, which have been kept at a test temperature of 180℃, into the mixing pot for mixing. The mixing time is 3 minutes and the mixing speed is 80 r / min.

[0036] Step C200: Collect the aggregate with the largest particle size in the asphalt mixture, fix it with resin, cut it into sheets, spray it with gold, and scan the thickness of the asphalt film on the surface of the aggregate using SEM. The specific steps are as follows:

[0037] Step C210: After the asphalt mixture is mixed, select several aggregates with the largest particle size in the asphalt mixture according to the different gradations.

[0038] Step C220: Cast one selected aggregate particle into the asphalt segregation pipe using epoxy resin to form a cylinder, let it stand for 24 hours, and then remove the cured cylinder.

[0039] Step C230, cutting the solidified aggregate and resin into a sheet with a thickness of 5 mm using a cutting machine;

[0040] Step C240, putting the sheet containing aggregate-bitumen-resin into a gold spraying device to spray gold;

[0041] Step C250, scanning the thickness of the bitumen film wrapped on the aggregate surface using a SEM device.

[0042] Step C300, according to the scanned bitumen film thickness, proposing a bitumen film wrapping uniformity evaluation index, and the bitumen film wrapping uniformity evaluation index is specifically as follows:

[0043]

[0044] Wherein,

[0045] In the formula: CUAF is the bitumen film wrapping uniformity evaluation index; ATAF is the bitumen film average thickness evaluation index, mm; n is the number of aggregates with the largest particle size in the bitumen mixture; AF1, AF2,..., AF n The first-n aggregate surface wrapped bitumen film thickness, mm.

[0046] Step C400, using the bitumen film wrapping uniformity evaluation index to evaluate the workability of the bitumen mixture. The greater the CUAF, the worse the bitumen distribution uniformity, and thus the worse the workability.

[0047] Example 2

[0048] The same as example 1, the difference is that in step C100, the bitumen PG-64 and aggregate AC-13 (mass ratio: 4.6:100) heated to 180°C are respectively put into the mixing kettle for mixing.

[0049] The SEM scanning diagram of the bitumen film thickness wrapped on the aggregate surface in step C200 is shown in Figure 2 (a).

[0050] The calculation process of the bitumen film wrapping uniformity evaluation index in step C300 is specifically as follows:

[0051]

[0052] Wherein,

[0053] In the formula: CUAF is the bitumen film wrapping uniformity evaluation index; ATAF is the bitumen film average thickness evaluation index, mm; n is the number of aggregates with the largest particle size in the bitumen mixture; AF1, AF2,..., AF nThe asphalt film thickness of the first-n aggregate, mm.

[0054] Example 3

[0055] The same as example 1, except that the asphalt PG-76 and aggregate AC-13 (mass ratio: 4.6:100) heated to 180℃ were respectively put into the mixing pot for mixing in step C100.

[0056] The SEM scanning diagram of the asphalt film thickness of the aggregate in step C200 is shown in Figure 2 (b).

[0057] The asphalt film thickness of the first-n aggregate, mm.

[0058]

[0059] Wherein,

[0060] In the formula: CUAF is the asphalt film wrapping uniformity evaluation index; ATAF is the asphalt film average thickness evaluation index, mm; n is the number of aggregates with the largest particle size in the asphalt mixture; AF1, AF2,..., AFn are the asphalt film thicknesses of the first-n aggregates, mm. n The asphalt film thickness of the first-n aggregate, mm.

[0061] Example 4

[0062] The same as example 1, except that the asphalt PG-64 and aggregate AC-20 (mass ratio: 4.6:100) heated to 180℃ were respectively put into the mixing pot for mixing in step C100.

[0063] The SEM scanning diagram of the asphalt film thickness of the aggregate in step C200 is shown in Figure 2 (c).

[0064] The asphalt film thickness of the first-n aggregate, mm.

[0065]

[0066] Wherein,

[0067] In the formula: CUAF is the asphalt film wrapping uniformity evaluation index; ATAF is the asphalt film average thickness evaluation index, mm; n is the number of aggregates with the largest particle size in the asphalt mixture; AF1, AF2,..., AFn are the asphalt film thicknesses of the first-n aggregates, mm. n The asphalt film thickness of the first-n aggregate, mm.

[0068] Example 5

[0069] The same as example 1, except that in step C100, the asphalt PG-76 and aggregate AC-20 (mass ratio: 4.6:100) heated to 180°C were respectively put into the stirring pot for mixing.

[0070] The SEM scanning image of the asphalt film wrapped on the surface of the aggregate in step C200 is shown in Fig. 2. Figure 2 (d).

[0071] The calculation process of the evaluation index of the uniformity of the asphalt film wrapping in step C300 is as follows:

[0072]

[0073] Wherein,

[0074] In the formula: CUAF is the evaluation index of the uniformity of the asphalt film wrapping; ATAF is the evaluation index of the average thickness of the asphalt film, mm; n is the number of the aggregate with the largest particle size in the asphalt mixture; AF1, AF2,..., AFn are the thicknesses of the asphalt films wrapped on the surfaces of the first-n aggregates, mm. n

[0075] Example 6

[0076] The same as example 1, except that in step C100, the asphalt PG-64 and aggregate AC-13 (mass ratio: 4.6:100) heated to 140°C were respectively put into the stirring pot for mixing.

[0077] The SEM scanning image of the asphalt film wrapped on the surface of the aggregate in step C200 is shown in Fig. 2. Figure 2 (e).

[0078] The calculation process of the evaluation index of the uniformity of the asphalt film wrapping in step C300 is as follows:

[0079]

[0080] Wherein,

[0081] In the formula: CUAF is the evaluation index of the uniformity of the asphalt film wrapping; ATAF is the evaluation index of the average thickness of the asphalt film, mm; n is the number of the aggregate with the largest particle size in the asphalt mixture; AF1, AF2,..., AFn are the thicknesses of the asphalt films wrapped on the surfaces of the first-n aggregates, mm. n

[0082] Example 7

[0083] ​​The same as example 1, except that in step C100, the asphalt PG-76 and aggregate AC-13 (mass ratio: 4.6:100) heated to 140°C are respectively put into the stirring pot for mixing.

[0084] The SEM scanning diagram of the asphalt film thickness on the surface of the aggregate in step C200 is shown in Figure 2 (f).

[0085] The calculation process of the asphalt film coating uniformity evaluation index in step C300 is as follows:

[0086]

[0087] Wherein,

[0088] In the formula: CUAF is the asphalt film coating uniformity evaluation index; ATAF is the asphalt film average thickness evaluation index, mm; n is the number of aggregates with the largest particle size in the asphalt mixture; AF1, AF2,..., AF n The asphalt film thickness on the surface of the first-n aggregate, mm.

[0089] Example 8

[0090] The same as example 1, except that in step C100, the asphalt PG-64 and aggregate AC-20 (mass ratio: 4.6:100) heated to 140°C are respectively put into the stirring pot for mixing.

[0091] The SEM scanning diagram of the asphalt film thickness on the surface of the aggregate in step C200 is shown in Figure 2 (g).

[0092] The calculation process of the asphalt film coating uniformity evaluation index in step C300 is as follows:

[0093]

[0094] Wherein,

[0095] In the formula: CUAF is the asphalt film coating uniformity evaluation index; ATAF is the asphalt film average thickness evaluation index, mm; n is the number of aggregates with the largest particle size in the asphalt mixture; AF1, AF2,..., AF n The asphalt film thickness on the surface of the first-n aggregate, mm.

[0096] Example 9

[0097] Similar to Example 1, except that in step C100, asphalt PG-76 and aggregate AC-20 (mass ratio: 4.6:100) that have been kept at 140°C are respectively put into the mixing pot for mixing.

[0098] See the SEM scan image of the asphalt film thickness coating the aggregate surface in step C200. Figure 2 (h).

[0099] The specific calculation process for the evaluation index of asphalt film adhesion uniformity in step C300 is as follows:

[0100]

[0101] in,

[0102] Where: CUAF—Evaluation index for uniformity of asphalt film coating; ATAF—Evaluation index for average thickness of asphalt film, mm; n is the number of aggregates with the largest particle size in the asphalt mixture; AF1, AF2, ... AF n —The thickness of the asphalt film adhering to the surface of the 1st to nth aggregates, in mm.

[0103] Using the asphalt film coating uniformity evaluation index (CUAF) obtained in Examples 2-9, the average thickness of the asphalt film and the uniformity of asphalt film coating in different asphalt mixtures were analyzed.

[0104] from Figure 3 and Figure 4 The results show that the lower the uniformity of asphalt film adhesion in different asphalt mixtures, the better the workability of the asphalt mixture. Simultaneously, the test results indicate that the mixing temperature of the asphalt mixture has a significant impact on its workability. It is clearly shown in the figure that, under the same asphalt type and mixture type, the CUAF of the asphalt mixture mixed at 180℃ is significantly lower than that of the asphalt mixture mixed at 140℃. At the same mixing temperature and mixture type, the CUAF of the PG-76 mixture is greater than that of the PG-76 mixture. Under the same mixing temperature and asphalt type, the CUAF of the AC-20 gradation asphalt mixture is greater than that of the AC-13 gradation asphalt mixture. This invention can accurately evaluate the mixing uniformity during the asphalt mixture mixing process, quantify the workability of asphalt mixtures, and provide a theoretical basis and data support for subsequent asphalt pavement performance evaluation.

[0105] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

Claims

1. A method for evaluating the workability of asphalt mixtures based on the uniformity of asphalt film coating, characterized in that, The steps are as follows: Step C100. Mix the asphalt mixture using an asphalt mixing planter; Step C200. Collect the aggregate with the largest particle size in the asphalt mixture, fix it with resin, cut it into sheets, spray it with gold, and scan the thickness of the asphalt film on the surface of the aggregate using SEM. The specific steps for collecting the largest aggregate particles in the asphalt mixture, fixing them with resin, cutting them into sheets, spraying them with gold, and scanning the thickness of the asphalt film on the surface of the aggregate using SEM are as follows: Step C210: After the asphalt mixture is mixed, select several aggregates with the largest particle size in the asphalt mixture according to the different gradations. Step C220: Cast one selected aggregate particle into the asphalt segregation pipe using epoxy resin to form a cylinder, let it stand for 24 hours, and then remove the cured cylinder. Step C230: Use a cutting machine to cut the cured aggregate and resin into thin sheets with a thickness of 5 mm; Step C240: Place the sheet containing aggregate-asphalt-resin into the gold spraying equipment and spray it with gold; Step C250: Use SEM equipment to scan the thickness of the asphalt film coating on the aggregate surface; Step C300. Based on the scanned asphalt film thickness, propose evaluation indicators for the uniformity of asphalt film coating. Specifically, the evaluation indicators for the uniformity of asphalt film coating are as follows: in, Where: CUAF—Evaluation index for uniformity of asphalt film coating; ATAF—Evaluation index for average thickness of asphalt film, mm; n is the number of aggregates with the largest particle size in the asphalt mixture; AF1, AF2, ... AF n —Thickness of the asphalt film adhering to the surface of the 1-n aggregates, mm; Step C400. Evaluate the workability of asphalt mixtures using the asphalt film coating uniformity evaluation index.

2. The method for evaluating the workability of asphalt mixtures based on the uniformity of asphalt film coating according to claim 1, characterized in that, In step C100, the asphalt mixture is mixed using an asphalt mixing planter as follows: aggregates and asphalt that have been kept at a test temperature of 180°C are separately put into a mixing pot for mixing. The mixing time is 3 minutes and the mixing speed is 80 r / min, thus obtaining the asphalt mixture.

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