A water-reactive cold-mixed asphalt mixture and its preparation method

Abstract

The present invention discloses a water-reactive cold-mix asphalt mixture, which is made from the following raw materials in parts by weight: 1 to 1.5 parts of dimethylformamide, 0.5 to 1 part of tung oil, 4 to 5 parts of matrix asphalt, 0.05 to 0.1 part of curing agent, and 100 parts of aggregate; when in use, 1 to 2 parts of reaction medium water are added; its preparation method includes: First, heating the matrix asphalt to 140°C to 150°C for standby; Second, adding dimethylformamide, tung oil, and curing agent into the standby matrix asphalt and stirring evenly to make cold-mix asphalt; Third, mixing the cold-mix asphalt with the aggregate to make a cold-mix asphalt mixture. In the water-reactive cold-mix asphalt mixture of the present invention, by adding dimethylformamide, tung oil and curing agent, and using water as an activator, the cold-mix asphalt mixture can quickly form strength. This mixture has quick setting and early strength, high density, good water resistance, few components, is green and environmentally friendly, and is suitable for pavement maintenance surface covering and pothole repair.

Description

Technical Field

[0001] The present invention belongs to the technical field of asphalt mixture preparation, and particularly relates to a water-reactive cold mix asphalt mixture and a preparation method thereof. Background Art

[0002] Potholes are typical diseases of asphalt pavements, which will seriously affect the smoothness of the pavement and driving comfort. If not repaired in time, under the combined action of heavy-duty vehicles and rainwater, potholes will develop rapidly, not only increasing the maintenance cost, but also seriously endangering the safety of drivers and passengers. Due to its great potential safety hazards, it is usually required in daily highway maintenance management that "potholes should not last overnight", that is, potholes should be repaired in time when they appear. Currently, the commonly used pothole repair technologies can be divided into two categories: hot patching method and cold patching method. The advantage of the hot patching method is good repair quality and strong durability, but the construction process is relatively complex, requiring special equipment for heating and mixing, with low construction efficiency and being greatly affected by temperature; the advantage of the cold patching method is that it does not require special equipment and can still be constructed in alpine regions or when the temperature is low in winter. However, traditional cold patching materials are mostly solvent-diluted materials, with slow strength formation, easy to disperse when encountering water, poor repair quality and short service life, and are generally only used for emergency maintenance. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a water-reactive cold mix asphalt mixture in view of the deficiencies of the above-mentioned prior art. In this water-reactive cold mix asphalt mixture, by adding dimethylformamide, tung oil and calcium hydroxide, and using water as an activator, the cold mix asphalt mixture can quickly form strength, with good repair quality, long service life, and shortened repair time, solving the shortcoming that traditional cold mix asphalt mixtures are afraid of water erosion.

[0004] To solve the above technical problem, the technical solution adopted by the present invention is: a water-reactive cold mix asphalt mixture, characterized in that it is made from the following raw materials in parts by weight: 1 - 1.5 parts of dimethylformamide, 0.5 - 1 part of tung oil, 4 - 5 parts of matrix asphalt, 0.05 - 0.1 part of curing agent, 100 parts of aggregate; calculated by weight, 1 - 2 parts of reaction medium water are added when the cold mix asphalt mixture is used.

[0005] In order to solve the persistent problem of traditional cold patch materials being afraid of water and give full play to the technological advantages of cold patch materials, the present invention has developed a water-reactive cold mix asphalt mixture composed of materials such as matrix asphalt, asphalt diluent dimethylformamide, tung oil, water reaction curing agent, and aggregate. By adding dimethylformamide and tung oil, the present invention rapidly undergoes a chemical reaction with the preferably calcium hydroxide curing agent in the reaction medium water, enabling the cold mix asphalt mixture to rapidly form strength. Among them, the carbonyl group (C=O) in dimethylformamide has a certain electrophilicity and undergoes a nucleophilic addition reaction with the hydroxide ion (OH-) in the calcium hydroxide aqueous solution, ultimately generating calcium formate. Calcium formate, as a concrete early strength agent, promotes the rapid formation of strength of the cold mix asphalt mixture; while tung oil and the calcium hydroxide aqueous solution are mixed to form tung oil-lime mortar, which can accelerate the formation of the early structure of the cold mix asphalt mixture. Therefore, the present invention uses water as the medium to promote the chemical reaction between dimethylformamide and tung oil and the curing agent, that is, water can activate the chemical reaction between dimethylformamide and tung oil and the curing agent. Therefore, water must be introduced during the strength formation process of the water-reactive cold mix asphalt mixture of the present invention, solving the shortcoming of traditional cold mix asphalt mixtures being afraid of water erosion.

[0006] The above-mentioned water-reactive cold mix asphalt mixture is characterized in that it is made from the following raw materials in parts by weight: 1 part of dimethylformamide, 0.5 part of tung oil, 4 parts of matrix asphalt, 0.05 part of curing agent, and 100 parts of aggregate; calculated by weight, 1 part of reaction medium water is added when the cold mix asphalt mixture is used.

[0007] The above-mentioned water-reactive cold mix asphalt mixture is characterized in that it is made from the following raw materials in parts by weight: 1.5 parts of dimethylformamide, 1 part of tung oil, 5 parts of matrix asphalt, 0.1 part of curing agent, and 100 parts of aggregate; calculated by weight, 2 parts of reaction medium water are added when the cold mix asphalt mixture is used.

[0008] The above-mentioned water-reactive cold mix asphalt mixture is characterized in that the matrix asphalt is 90# road petroleum asphalt meeting the requirements of the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40-2004).

[0009] The above-mentioned water-reactive cold mix asphalt mixture is characterized in that the curing agent is calcium hydroxide. This type of curing agent can not only promote the rapid formation of strength of the cold mix asphalt mixture, but also has low cost and wide application, which is beneficial to the large-scale production and popularization of the cold mix asphalt mixture of the present invention.

[0010] The above-mentioned water-reactive cold mix asphalt mixture is characterized in that the aggregate includes coarse aggregate of 5mm - 10mm, fine aggregate of 0 - 5mm, and mineral powder, and the mass ratio of coarse aggregate:fine aggregate:mineral powder = 60:38:2.

[0011] Meanwhile, the present invention also discloses a preparation method of the water-reactive cold mix asphalt mixture as described above, which is characterized in that the method comprises the following steps:

[0012] Step 1: Heat the base asphalt to 140°C - 150°C for standby;

[0013] Step 2: Add dimethylformamide, tung oil, and curing agent to the base asphalt prepared in Step 1 and stir evenly to make cold mix asphalt;

[0014] Step 3: Mix the cold mix asphalt prepared in Step 2 with aggregates to make cold mix asphalt mixture.

[0015] By controlling the adding sequence and method of each raw material, the present invention ensures that the cold mix asphalt mixture has good fluidity at normal temperature and realizes the cold mix preparation of asphalt mixture.

[0016] For the above preparation method, it is characterized in that the cold mix asphalt mixture prepared in Step 3 is filled into a test mold, water is sprayed on the surface, and then it is compacted or rolled to form, and cold mix asphalt mixture specimens are obtained for mechanical property testing; based on the weight parts of the cold mix asphalt mixture, the added weight parts of water are 1 - 2 parts. This water addition amount ensures the full reaction of dimethylformamide, tung oil, and curing agent in the cold mix asphalt mixture.

[0017] For the above preparation method, it is characterized in that the mechanical property testing includes Marshall stability, immersion Marshall residual stability, freeze-thaw splitting strength ratio, and 60°C rutting test. The performance of traditional cold mix asphalt mixture is far from reaching the technical level of hot mix asphalt mixture, so its evaluation indexes are very simple, only including Marshall stability and immersion Marshall residual stability, and the test temperature is 25°C, rather than 60°C for hot mix asphalt mixture; for the developed water-reactive cold mix asphalt mixture, the test indexes and test temperature adopted by the present invention completely refer to the evaluation indexes of hot mix asphalt mixture for horizontal comparison with hot mix asphalt mixture.

[0018] The present invention has the following advantages compared with the prior art:

[0019] 1. In the water-reactive cold mix asphalt mixture of the present invention, by adding dimethylformamide, tung oil, and curing agent, and using water as an activator to promote the chemical gel curing reaction, the cold mix asphalt mixture can quickly form strength, has good repair quality and long service life, and solves the shortcoming that traditional cold mix asphalt mixture is afraid of water erosion.

[0020] 2. In the water-reactive cold mix asphalt mixture of the present invention, by adding dimethylformamide and tung oil, the asphalt still has good fluidity at normal temperature after dilution, has high looseness and good fluidity in the anhydrous state, has excellent workability in construction, can coexist with the water-reactive curing agent for a long time during sealed storage, and has good stability. When in use, after the pavement is paved, the surface is wetted with water and rolled in time, which can activate the curing agent to rapidly undergo a water-activation reaction inside the mixture to form strength. The initial strength can be rapidly formed in about 30 minutes, reaching the state of initial surface hardening. The strength can be basically formed in 2 hours, and the Marshall stability can reach more than 6 kN after 24 hours. Moreover, all technical indicators can basically reach the technical level of hot mix asphalt mixture. Compared with the preparation cycle of more than one week for traditional solvent-based cold mix asphalt mixture to form early strength after the solvent slowly volatilizes, the time for repairing the pavement is greatly shortened.

[0021] 3. Compared with solvent-based cold mix asphalt mixture, in order to ensure the workability of the mixture and reserve space for the later volatilization of the solvent, its mineral aggregate gradation is mainly single-sized aggregate, and the amount of manufactured sand and mineral powder is very small or even not used, resulting in a large void ratio on the pavement after construction and compaction, making it difficult to ensure the density. Rainwater is easily infiltrated, making the water damage resistance of cold mix asphalt mixture, which already has poor water stability, even worse and the durability insufficient. At the same time, the water-reactive cold mix asphalt mixture of the present invention has excellent workability itself and has good fluidity without heating. Therefore, even if an AC type dense gradation is adopted, it can ensure good workability of the mixture during construction, ensuring that the pavement after construction can reach a high density from the gradation, waterproof and impermeable, and achieve the durability goal.

[0022] 4. Compared with traditional cold mix asphalt mixture with poor performance and low early strength, in the current field of asphalt pavement maintenance, it is usually only used as a temporary repair material or only for the pavement base or lower layer for short-term repair. The water-reactive cold mix asphalt mixture of the present invention has rapid setting, early strength, high density, good water resistance, few components, and is green and environmentally friendly, and can completely replace hot mix asphalt mixture for pavement maintenance overlay, pothole repair, etc.

[0023] The technical solution of the present invention will be further described in detail below through examples. Detailed implementation mode

[0024] Example 1

[0025] The water-reactive cold mix asphalt mixture of this embodiment is made from the following raw materials by weight: 1 part of dimethylformamide, 0.5 part of tung oil, 4 parts of base asphalt, 0.05 part of curing agent calcium hydroxide, and 100 parts of aggregate; by weight, 1 part of reaction medium water is added when the cold mix asphalt mixture is used; the base asphalt is 90# road petroleum asphalt meeting the requirements of "Technical Specifications for Construction of Highway Asphalt Pavement" (JTG F40-2004); the aggregate includes coarse aggregate of 5 mm to 10 mm, fine aggregate of 0 to 5 mm, and mineral powder, and the mass ratio of coarse aggregate: fine aggregate: mineral powder = 60:38:2.

[0026] The preparation method of the water-reactive cold mix asphalt mixture of this embodiment includes the following steps:

[0027] Step 1: Heat the base asphalt to 140°C to 150°C for later use;

[0028] Step 2: Add dimethylformamide, tung oil, and the curing agent to the base asphalt prepared in Step 1 and stir evenly to make cold mix asphalt;

[0029] Step 3: Mix the cold mix asphalt prepared in Step 2 with the aggregate to make a cold mix asphalt mixture.

[0030] Example 2

[0031] The difference between this embodiment and Example 1 is: 1.5 parts of dimethylformamide, 1 part of tung oil, 5 parts of base asphalt, 0.1 part of curing agent calcium hydroxide, and 100 parts of aggregate; by weight, 2 parts of reaction medium water are added when the cold mix asphalt mixture is used.

[0032] Example 3

[0033] The difference between this embodiment and Example 1 is: 10 parts of dimethylformamide, 1 part of tung oil, 5 parts of base asphalt, 0.1 part of curing agent calcium hydroxide, and 100 parts of aggregate; by weight, 1 part of reaction medium water is added when the cold mix asphalt mixture is used.

[0034] Example 4

[0035] The difference between this embodiment and Example 1 is: 1.5 parts of dimethylformamide, 0.5 part of tung oil, 4.5 parts of base asphalt, 0.05 part of curing agent calcium hydroxide, and 100 parts of aggregate; by weight, 1 part of reaction medium water is added when the cold mix asphalt mixture is used.

[0036] Example 5

[0037] The differences between this embodiment and Embodiment 1 are as follows: 1 part of dimethylformamide, 0.5 part of tung oil, 5 parts of matrix asphalt, 0.1 part of curing agent calcium hydroxide, and 100 parts of aggregate; by weight, 2 parts of reaction medium water are added when the cold mix asphalt mixture is used.

[0038] The mineral aggregate gradation composition of the water-reactive cold mix asphalt mixture in Embodiments 1 to 5 of the present invention is shown in Table 1 below.

[0039] Table 1 Mineral aggregate gradation composition of asphalt mixture

[0040]

[0041] The water-reactive cold mix asphalt mixtures prepared in Embodiments 1 to 5 of the present invention are respectively filled into test molds, and water is sprayed on the surface. Based on the weight parts of the cold mix asphalt mixture, the added weight parts of water are 1 to 2 parts, and then they are compacted or rolled into shape to obtain cold mix asphalt mixture specimens. Then, mechanical property tests are carried out in accordance with the relevant test regulations of the Ministry of Transport's issued standard JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", including Marshall stability, immersion Marshall residual stability, freeze-thaw splitting strength ratio, 60°C rutting test, that is, 60°C dynamic stability test. The results are shown in Table 2 below.

[0042] Table 2 Comparative test results of the performance of water-reactive cold mix asphalt mixture

[0043]

[0044] As can be seen from Table 2, the performance of the water-reactive cold mix asphalt mixture of the present invention can reach the technical level of hot mix asphalt mixture under the condition of cold mixing at normal temperature, and can be widely used in the maintenance and repair of asphalt pavements in various climate regions.

[0045] The above are only the preferred embodiments of the present invention and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent variations made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A water-reactive cold mix asphalt mixture, characterized in that, It is made from the following raw materials in parts by weight: 1 to 1.5 parts of dimethylformamide, 0.5 to 1 part of tung oil, 4 to 5 parts of matrix asphalt, 0.05 to 0.1 part of curing agent, and 100 parts of aggregate; the curing agent is calcium hydroxide; Calculated by weight, 1 to 2 parts of reaction medium water are added when the cold mix asphalt mixture is used.

2. The water-reactive cold mix asphalt mixture according to claim 1, wherein It is made from the following raw materials in parts by weight: 1 part of dimethylformamide, 0.5 part of tung oil, 4 parts of matrix asphalt, 0.05 part of curing agent, and 100 parts of aggregate; calculated by weight, 1 part of reaction medium water is added when the cold mix asphalt mixture is used.

3. The water-reactive cold mix asphalt mixture according to claim 1, characterized in that, It is made from the following raw materials in parts by weight: 1.5 parts of dimethylformamide, 1 part of tung oil, 5 parts of matrix asphalt, 0.1 part of curing agent, and 100 parts of aggregate; calculated by weight, 2 parts of reaction medium water are added when the cold mix asphalt mixture is used.

4. The water-reactive cold mix asphalt mixture according to claim 1, wherein The matrix asphalt is 90# road petroleum asphalt that meets the requirements of the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40-2004).

5. The water-reactive cold mix asphalt mixture according to claim 1, characterized in that, The aggregate includes coarse aggregate of 5 mm to 10 mm, fine aggregate of 0 to 5 mm, and mineral powder, and the mass ratio of coarse aggregate∶fine aggregate∶mineral powder = 60∶38∶2.

6. A preparation method of a water-reactive cold-mix asphalt mixture according to any one of claims 1 to 5, characterized in that, The method includes the following steps: Step 1: Heat the matrix asphalt to 140°C to 150°C for standby; Step 2: Add dimethylformamide, tung oil, and curing agent to the matrix asphalt prepared in Step 1 and stir evenly to make cold mix asphalt; Step 3: Mix the cold mix asphalt prepared in Step 2 with the aggregate to make a cold mix asphalt mixture.

7. The preparation method according to claim 6, characterized in that, Put the cold mix asphalt mixture prepared in Step 3 into a test mold, spray water on the surface, and then compact or roll it into shape to obtain a cold mix asphalt mixture specimen for mechanical property testing; based on the weight parts of the cold mix asphalt mixture, the added weight parts of water are 1 to 2 parts.

8. The preparation method according to claim 7, characterized in that, The mechanical property testing includes Marshall stability, immersion Marshall residual stability, freeze-thaw splitting strength ratio, and 60°C rutting test.

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