RCA modified asphalt mixture for highway construction and preparation method thereof

Abstract

The invention relates to the technical field of road engineering, and discloses an RCA modified asphalt mixture for highway construction, the RCA modified asphalt mixture is prepared from mineral aggregate, matrix asphalt and RCA, the content of the matrix asphalt is 3.9-4.3% of the mass of the mineral aggregate, the content of the RCA is 1.0-2.0% of the mass of the mineral aggregate, and the invention also provides a preparation method of the RCA modified asphalt mixture. Compared with the traditional SBS modified asphalt mixture, the RCA modified asphalt mixture prepared by the invention has more excellent high-temperature rut resistance; according to the production process, the RCA is directly mixed with the matrix asphalt and the aggregate by adopting a'dry method 'process, so that the production process is relatively simple; the compatibility of the RCA and the matrix asphalt is good, and the performance of the produced RCA modified asphalt mixture is more stable.

Description

Technical Field

[0001] The invention relates to the technical field of road engineering, and in particular to an RCA modified asphalt mixture for highway construction and a preparation method thereof. Background Art

[0002] At present, the most widely used asphalt mixture in road construction is SBS modified asphalt mixture. A large number of test results and engineering practice experience have proved that the high temperature performance of SBS modified asphalt mixture is limited. Asphalt pavement constructed with it will still have rutting, potholes and other defects shortly after opening to traffic. In addition, SBS polymer modified asphalt needs to be pre-mixed, and the production process of SBS modified asphalt mixture is relatively complicated. In addition, the storage stability of SBS modified asphalt is poor, which also directly affects the performance of SBS modified asphalt mixture.

[0003] RCA modified asphalt mixture based on composite rock asphalt modifier (RCA) can solve the above problems. RCA is made of Albanian rock asphalt and nano titanium dioxide. Albanian rock asphalt has stable performance and good compatibility with base asphalt. Nano titanium dioxide can be evenly distributed in the base asphalt as a reinforcement due to its large specific surface area, greatly improving the performance of the base asphalt. Summary of the invention

[0004] In view of the above problems, the technical problem to be solved by the present invention is to provide an RCA modified asphalt mixture with excellent high temperature performance, simple production process and stable performance and a preparation method thereof.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is as follows: an RCA modified asphalt mixture for highway construction is made of mineral material, base asphalt and RCA, wherein the base asphalt content is 3.9% to 4.3% of the mineral material mass, and the RCA content is 1.0% to 2.0% of the mineral material mass.

[0006] The natural asphalt content of RCA is 40% to 80%, the density is (1.4 to 1.6) g / cm3, the flash point is not less than 230°C, and the moisture content is not more than 2%.

[0007] Preferably, the mineral material consists of aggregate and mineral powder, and the aggregate includes aggregate A with a particle size range of 11 to 24 mm, aggregate B with a particle size range of 7 to 11 mm, aggregate C with a particle size range of 4 to 7 mm, and aggregate D with a particle size range of 0 to 4 mm.

[0008] Preferably, the aggregate is one of limestone and diabase, and the mineral powder is obtained by grinding the limestone.

[0009] Preferably, the mineral material dosage composition is as follows, by weight: 40-48 parts of aggregate A, 24-30 parts of aggregate B, 3-8 parts of aggregate C, 20-28 parts of aggregate D, and 2-4 parts of mineral powder.

[0010] Preferably, the mineral material usage composition is, by weight: 42 parts of aggregate A, 27 parts of aggregate B, 5 parts of aggregate C, 23 parts of aggregate D, and 3 parts of mineral powder.

[0011] Preferably, the base asphalt has a needle penetration of 40 to 100 dmm, a softening point of 42 to 52°C, and an elongation of not less than 100 cm at 15°C.

[0012] A method for preparing an RCA modified asphalt mixture comprises the following steps:

[0013] (1) Weigh the required mass of aggregates of different particle size ranges, mineral powder, matrix asphalt and RCA;

[0014] (2) heating the base asphalt weighed in step (1) to 155-175° C. to make it completely molten, adding the RCA weighed in step (1) and stirring for 2-4 minutes to obtain liquid RCA modified asphalt;

[0015] (3) At the same time, the aggregate weighed in step (1) is heated to 175-185° C., the liquid RCA modified asphalt in step (2) is mixed into the heated aggregate while hot, and stirred for 2-4 minutes under continuous heating to obtain RCA modified asphalt macadam;

[0016] (4) The mineral powder weighed in step (1) is preheated to 170-180° C., added to the RCA-modified asphalt gravel continuously heated in step (3), and stirred for 2-3 minutes to prepare the RCA-modified asphalt mixture.

[0017] Preferably, the stirring rate in step (2) is 300 to 500 r / min, and the stirring rate in step (3) and step (4) is 100 to 300 r / min.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) Compared with SBS modified asphalt mixture, RCA modified asphalt mixture has significantly improved high temperature rutting resistance, which can avoid early rutting, potholes and other diseases after the new asphalt pavement is opened to traffic, greatly improving the performance of the asphalt pavement;

[0020] (2) The production process of RCA modified asphalt mixture is to use the "dry process" to mix RCA directly with base asphalt and aggregate. There is no need to modify the base asphalt in advance at the asphalt processing plant for storage and transportation. Therefore, its production process is relatively simple, which can indirectly save engineering costs.

[0021] (3) The RCA modifier used in RCA modified asphalt mixture is mainly composed of rock asphalt, which has stable performance and good compatibility with base asphalt. Therefore, the performance of the RCA modified asphalt mixture produced is more stable than that of SBS modified asphalt mixture;

[0022] (4) Compared with SBS modified asphalt mixture, RCA modified asphalt mixture has better anti-ultraviolet aging performance and can effectively extend the service life of asphalt pavement. DETAILED DESCRIPTION

[0023] The specific implementation modes of the present invention are further described below in conjunction with examples.

[0024] Example 1

[0025] A RCA modified asphalt mixture for highway construction is made of mineral material, base asphalt and RCA, wherein the base asphalt content is 4.3% of the mineral material mass, and the RCA content is 1.0% of the mineral material mass;

[0026] The mineral material is composed of aggregate and mineral powder. The aggregate includes aggregate A with a particle size range of 11 to 24 mm, aggregate B with a particle size range of 7 to 11 mm, aggregate C with a particle size range of 4 to 7 mm, and aggregate D with a particle size range of 0 to 4 mm. The aggregate is limestone, and the mineral powder is obtained by grinding limestone.

[0027] By weight, the mineral material usage is composed of: 45 parts of aggregate A, 25 parts of aggregate B, 5 parts of aggregate C, 23 parts of aggregate D, and 2 parts of mineral powder;

[0028] The penetration of the matrix asphalt is 40-100 dmm, the softening point is 42-52°C, and the elongation at 15°C is not less than 100 cm;

[0029] A method for preparing an RCA modified asphalt mixture comprises the following steps:

[0030] (1) Weigh the required mass of aggregates of different particle size ranges, mineral powder, matrix asphalt and RCA;

[0031] (2) heating the base asphalt weighed in step (1) to 155° C. to make it completely molten, adding the RCA weighed in step (1) and stirring for 2 min at a stirring rate of 300 r / min to obtain liquid RCA modified asphalt;

[0032] (3) At the same time, the aggregate weighed in step (1) is heated to 175° C., the liquid RCA modified asphalt in step (2) is mixed into the heated aggregate while hot, and stirred for 2 minutes under continuous heating at a stirring rate of 100 r / min to obtain RCA modified asphalt macadam;

[0033] (4) The mineral powder weighed in step (1) is preheated to 170° C., added to the RCA modified asphalt gravel continuously heated in step (3), and stirred for 2 min at a stirring rate of 100 r / min to prepare an RCA modified asphalt mixture.

[0034] Example 2

[0035] A RCA modified asphalt mixture for highway construction is made of mineral material, base asphalt and RCA, wherein the base asphalt content is 4.1% of the mineral material mass, and the RCA content is 1.5% of the mineral material mass;

[0036] The mineral material is composed of aggregate and mineral powder. The aggregate includes aggregate A with a particle size range of 11 to 24 mm, aggregate B with a particle size range of 7 to 11 mm, aggregate C with a particle size range of 4 to 7 mm, and aggregate D with a particle size range of 0 to 4 mm. The aggregate is limestone, and the mineral powder is obtained by grinding limestone.

[0037] By weight, the mineral material usage is: 42 parts of aggregate A, 27 parts of aggregate B, 5 parts of aggregate C, 23 parts of aggregate D, and 3 parts of mineral powder;

[0038] The penetration of the matrix asphalt is 40-100 dmm, the softening point is 42-52°C, and the elongation at 15°C is not less than 100 cm;

[0039] A method for preparing an RCA modified asphalt mixture comprises the following steps:

[0040] (1) Weigh the required mass of aggregates of different particle size ranges, mineral powder, matrix asphalt and RCA;

[0041] (2) heating the base asphalt weighed in step (1) to 160° C. to make it completely molten, adding the RCA weighed in step (1) and stirring for 3 min at a stirring rate of 400 r / min to obtain liquid RCA modified asphalt;

[0042] (3) At the same time, the aggregate weighed in step (1) is heated to 180° C., and the liquid RCA modified asphalt in step (2) is mixed into the heated aggregate while hot, and stirred for 3 minutes under continuous heating at a stirring rate of 200 r / min to obtain RCA modified asphalt macadam;

[0043] (4) The mineral powder weighed in step (1) is preheated to 175° C., added to the RCA-modified asphalt gravel continuously heated in step (3), and stirred for 3 min at a stirring rate of 200 r / min to prepare an RCA-modified asphalt mixture.

[0044] Example 3

[0045] A RCA modified asphalt mixture for highway construction is made of mineral material, base asphalt and RCA, wherein the base asphalt content is 3.9% of the mineral material mass, and the RCA content is 2% of the mineral material mass;

[0046] The mineral material is composed of aggregate and mineral powder. The aggregate includes aggregate A with a particle size range of 11 to 24 mm, aggregate B with a particle size range of 7 to 11 mm, aggregate C with a particle size range of 4 to 7 mm, and aggregate D with a particle size range of 0 to 4 mm. The aggregate is diabase, and the mineral powder is obtained by grinding limestone.

[0047] By weight, the mineral material usage is composed of: 40 parts of aggregate A, 26 parts of aggregate B, 5 parts of aggregate C, 26 parts of aggregate D, and 3 parts of mineral powder;

[0048] The penetration of the matrix asphalt is 40-100 dmm, the softening point is 42-52°C, and the elongation at 15°C is not less than 100 cm;

[0049] A method for preparing an RCA modified asphalt mixture comprises the following steps:

[0050] (1) Weigh the required mass of aggregates of different particle size ranges, mineral powder, matrix asphalt and RCA;

[0051] (2) heating the base asphalt weighed in step (1) to 175° C. to make it completely molten, adding the RCA weighed in step (1) and stirring for 4 min at a stirring rate of 500 r / min to obtain liquid RCA modified asphalt;

[0052] (3) At the same time, the aggregate weighed in step (1) is heated to 185° C., the liquid RCA modified asphalt in step (2) is mixed into the heated aggregate while hot, and stirred for 4 minutes under continuous heating at a stirring rate of 300 r / min to obtain RCA modified asphalt macadam;

[0053] (4) The mineral powder weighed in step (1) is preheated to 180° C., added to the RCA-modified asphalt gravel continuously heated in step (3), and stirred for 3 min at a stirring rate of 300 r / min to prepare an RCA-modified asphalt mixture.

[0054] Control group 1

[0055] SBS modified asphalt mixture is made of mineral aggregate and SBS modified asphalt, and the content of SBS modified asphalt is 4.2% of the mineral aggregate mass;

[0056] SBS modified asphalt mixture uses the mineral material used to prepare RCA modified asphalt mixture. The mineral material consists of aggregate and mineral powder. The aggregate includes aggregate A with a particle size range of 11 to 24 mm, aggregate B with a particle size range of 7 to 11 mm, aggregate C with a particle size range of 4 to 7 mm, and aggregate D with a particle size range of 0 to 4 mm. The aggregate is limestone, and the mineral powder is obtained by grinding limestone.

[0057] By weight, the composition of mineral materials is: 45 parts of aggregate A, 25 parts of aggregate B, 5 parts of aggregate C, 23 parts of aggregate D, and 3 parts of mineral powder;

[0058] The preparation process of SBS asphalt mixture follows the recommended method in "Test Code for Asphalt and Asphalt Mixture for Highway Engineering" (JTGE20-2011).

[0059] Control group 2

[0060] A RCA modified asphalt mixture for highway construction is made of mineral material, base asphalt and RCA, wherein the base asphalt content is 4.5% of the mineral material mass, and the RCA content is 0.5% of the mineral material mass;

[0061] The mineral material is composed of aggregate and mineral powder. The aggregate includes aggregate A with a particle size range of 11 to 24 mm, aggregate B with a particle size range of 7 to 11 mm, aggregate C with a particle size range of 4 to 7 mm, and aggregate D with a particle size range of 0 to 4 mm. The aggregate is limestone, and the mineral powder is obtained by grinding limestone.

[0062] By weight, the mineral material usage is composed of: 46 parts of aggregate A, 24 parts of aggregate B, 5 parts of aggregate C, 23 parts of aggregate D, and 2 parts of mineral powder;

[0063] The penetration of the matrix asphalt is 40-100 dmm, the softening point is 42-52°C, and the elongation at 15°C is not less than 100 cm;

[0064] A method for preparing an RCA modified asphalt mixture comprises the following steps:

[0065] (1) Weigh the required mass of aggregates of different particle size ranges, mineral powder, matrix asphalt and RCA;

[0066] (2) heating the base asphalt weighed in step (1) to 155° C. to make it completely molten, adding the RCA weighed in step (1) and stirring for 2 min at a stirring rate of 300 r / min to obtain liquid RCA modified asphalt;

[0067] (3) At the same time, the aggregate weighed in step (1) is heated to 175° C., the liquid RCA modified asphalt in step (2) is mixed into the heated aggregate while hot, and stirred for 2 minutes under continuous heating at a stirring rate of 100 r / min to obtain RCA modified asphalt macadam;

[0068] (4) The mineral powder weighed in step (1) is preheated to 170° C., added to the RCA modified asphalt gravel continuously heated in step (3), and stirred for 2 min at a stirring rate of 100 r / min to prepare an RCA modified asphalt mixture.

[0069] Control group 3

[0070] A RCA modified asphalt mixture for highway construction is made of mineral material, base asphalt and RCA, wherein the base asphalt content is 3.7% of the mineral material mass, and the RCA content is 2.5% of the mineral material mass;

[0071] The mineral material is composed of aggregate and mineral powder. The aggregate includes aggregate A with a particle size range of 11 to 24 mm, aggregate B with a particle size range of 7 to 11 mm, aggregate C with a particle size range of 4 to 7 mm, and aggregate D with a particle size range of 0 to 4 mm. The aggregate is limestone, and the mineral powder is obtained by grinding limestone.

[0072] By weight, the mineral material usage is as follows: 40 parts of aggregate A, 26 parts of aggregate B, 4 parts of aggregate C, 27 parts of aggregate D, and 3 parts of mineral powder;

[0073] The penetration of the matrix asphalt is 40-100 dmm, the softening point is 42-52°C, and the elongation at 15°C is not less than 100 cm;

[0074] A method for preparing an RCA modified asphalt mixture comprises the following steps:

[0075] (1) Weigh the required mass of aggregates of different particle size ranges, mineral powder, matrix asphalt and RCA;

[0076] (2) heating the base asphalt weighed in step (1) to 155° C. to make it completely molten, adding the RCA weighed in step (1) and stirring for 2 min at a stirring rate of 300 r / min to obtain liquid RCA modified asphalt;

[0077] (3) At the same time, the aggregate weighed in step (1) is heated to 175° C., the liquid RCA modified asphalt in step (2) is mixed into the heated aggregate while hot, and stirred for 2 minutes under continuous heating at a stirring rate of 100 r / min to obtain RCA modified asphalt macadam;

[0078] (4) The mineral powder weighed in step (1) is preheated to 170° C., added to the RCA modified asphalt gravel continuously heated in step (3), and stirred for 2 min at a stirring rate of 100 r / min to prepare an RCA modified asphalt mixture.

[0079] The performance of the RCA modified asphalt mixture of the present invention is further illustrated by an experimental report.

[0080] The experimental samples of the RCA modified asphalt mixtures prepared in Examples 1 to 3 and the experimental samples prepared in Control Groups 1 to 3 were tested.

[0081] According to the "Highway Engineering Asphalt and Asphalt Mixture Test Procedure" (JTG E20-2011), rutting tests were performed on RCA modified asphalt mixture and SBS modified asphalt mixture respectively to further verify the high temperature performance of the present invention. The rutting test results of the modified asphalt mixture are shown in Table 1; after RTFOT, the RCA modified asphalt and SBS modified asphalt were respectively subjected to performance evaluation of their residues to indirectly verify the anti-aging performance of the RCA modified asphalt mixture. The test results of the residue after RTFOT of the modified asphalt are shown in Table 2; rutting tests were performed on RCA modified asphalt mixtures with different RCA contents to determine the value range of the RCA content. The rutting test results of RCA modified asphalt mixtures with different RCA contents are shown in Table 3. The relevant items were determined according to the "Highway Asphalt Pavement Construction Technical Specification" (JTG F40-2004).

[0082] Table 1 Test results of modified asphalt mixture rutting test

[0083]

[0084] Table 2 Residue test results after RTFOT of modified asphalt

[0085]

[0086] Table 3 Rutting test results of RCA modified asphalt mixtures with different RCA contents

[0087]

[0088] Control group 1 is SBS modified asphalt mixture, control group 2 is RCA modified asphalt mixture with RCA content of 0.5% of the mass of mineral material, and control group 3 is RCA modified asphalt mixture with RCA content of 2.5% of the mass of mineral material. The high temperature rutting resistance of asphalt mixture is evaluated by rutting test. The test index adopts dynamic stability DS, the standard test temperature is 60℃, and the contact pressure between the test wheel and the specimen is 0.7Mpa±0.05Mpa. Table 1 is the test results of rutting test of modified asphalt mixture. It can be seen from the test results in Table 1 that the measured value of dynamic stability DS of RCA modified asphalt mixture is significantly higher than that of SBS modified asphalt mixture, indicating that RCA modified asphalt mixture has better high temperature rutting resistance, and RCA modification can significantly improve the high temperature performance of asphalt mixture. Table 2 shows the test results of the residue after RTFOT of modified asphalt. It can be seen from the test results in Table 2 that the mass loss of the residue after RTFOT of RCA modified asphalt is smaller and the penetration ratio is higher, indicating that compared with SBS modified asphalt, RCA modified asphalt has better anti-aging performance and can effectively extend the service life of asphalt pavement. Table 3 shows the rutting test results of RCA modified asphalt mixtures with different RCA contents. It can be seen from the test results in Table 3 that when the RCA content is less than 1% or greater than 2%, the high temperature performance of RCA modified asphalt mixtures meets the technical requirements, but is worse than the high temperature anti-rutting performance of conventional SBS modified asphalt mixtures.

[0089] The above description is a detailed description of the preferred feasible embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modified changes completed under the technical spirit suggested by the present invention should belong to the patents covered by the present invention.

Claims

1. A RCA modified asphalt mixture for highway construction, characterized in that: It is made of mineral material, matrix asphalt and RCA, wherein the content of the matrix asphalt is 3.9% to 4.3% of the mass of the mineral material, and the content of the RCA is 1.0% to 2.0% of the mass of the mineral material.

2. The RCA modified asphalt mixture for highway construction according to claim 1, characterized in that: The mineral material consists of aggregate and mineral powder. The aggregate includes aggregate A with a particle size range of 11 to 24 mm, aggregate B with a particle size range of 7 to 11 mm, aggregate C with a particle size range of 4 to 7 mm, and aggregate D with a particle size range of 0 to 4 mm.

3. The RCA modified asphalt mixture for highway construction according to claim 2, characterized in that: The aggregate is one of limestone and diabase, and the mineral powder is obtained by grinding the limestone.

4. The RCA modified asphalt mixture for highway construction according to claim 2 or 3, characterized in that: In parts by weight, the mineral material usage is composed of: 40-48 parts of aggregate A, 24-30 parts of aggregate B, 3-8 parts of aggregate C, 20-28 parts of aggregate D, and 2-4 parts of mineral powder.

5. The RCA modified asphalt mixture for highway construction according to claim 4, characterized in that: In parts by weight, the mineral material usage is composed of: 42 parts of aggregate A, 27 parts of aggregate B, 5 parts of aggregate C, 23 parts of aggregate D, and 3 parts of mineral powder.

6. The RCA modified asphalt mixture for highway construction according to claim 1, characterized in that: The base asphalt has a needle penetration of 40 to 100 dmm, a softening point of 42 to 52°C, and an elongation of not less than 100 cm at 15°C.

7. A method for preparing the RCA modified asphalt mixture as described in any one of 1-6, characterized in that: The steps include: (1) Weigh the required mass of aggregates of different particle size ranges, mineral powder, matrix asphalt and RCA; (2) heating the base asphalt weighed in step (1) to 155-175° C. to make it completely molten, adding the RCA weighed in step (1) and stirring for 2-4 minutes to obtain liquid RCA modified asphalt; (3) At the same time, the aggregate weighed in step (1) is heated to 175-185° C., the liquid RCA modified asphalt in step (2) is mixed into the heated aggregate while hot, and stirred for 2-4 minutes under continuous heating to obtain RCA modified asphalt macadam; (4) The mineral powder weighed in step (1) is preheated to 170-180° C., added to the RCA-modified asphalt gravel continuously heated in step (3), and stirred for 2-3 minutes to prepare the RCA-modified asphalt mixture.

8. The RCA modified asphalt mixture for highway construction according to claim 7, characterized in that: The stirring rate in step (2) is 300 to 500 r / min, and the stirring rate in step (3) and step (4) is 100 to 300 r / min.

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