Preparation method of emulsified asphalt mortar and emulsified asphalt cold recycling mixture

Abstract

This invention belongs to the field of road engineering and relates to emulsified asphalt mortar. It discloses a method for preparing emulsified asphalt mortar and cold recycled emulsified asphalt mixture. The method includes: mixing component I and a silane coupling agent to obtain a combined liquid, wherein the mass ratio of component I to the silane coupling agent is 1:0.7-1.2; adding the combined liquid and cement to the emulsified asphalt and mixing thoroughly, wherein the amount of the combined liquid added accounts for 0.5-2 wt% of the mass of the emulsified asphalt, and the amount of cement added accounts for 30-40 wt% of the mass of the emulsified asphalt; by mass, the raw materials for preparing component I include: 8-11 parts of methyl allyl polyoxyethylene ether, 1-2.5 parts of ascorbic acid, 2-4 parts of maleic acid-acrylic acid copolymer, 1.5-4 parts of mercaptopropionic acid, 2-3 parts of ammonium persulfate, and 75-85 parts of water. This invention improves the workability of emulsified asphalt by mixing and adding three materials into it, thereby enhancing the dispersibility of the emulsified asphalt to achieve more uniform coating of RAP, and significantly improving the coating ability of the emulsified asphalt to RAP.

Description

Technical Field

[0001] This invention belongs to the field of road engineering and relates to emulsified asphalt mortar, specifically to a method for improving the coating ability of emulsified asphalt mortar on RAP. Background Technology

[0002] Using RAP (Recycled Asphalt Pulverized Asphalt) to prepare emulsified asphalt cold recycled mixtures is one of the main applications of recycled asphalt pavement materials (RAP). However, some problems arise in this application. When emulsified asphalt mortar coats RAP, the two penetrate each other due to the concentration difference, resulting in diverse characteristics of the internal interface of the cold recycled mixture. The coating state of the internal interface of the cold recycled mixture is closely related to its interface strength and macroscopic properties. Flocculation is prone to occur during the mixing of emulsified asphalt mortar and RAP, leading to easy separation of the emulsified asphalt after demulsification and difficulty in forming a continuous phase. Ultimately, this can easily cause the emulsified asphalt mortar and RAP to detach during the coating process, seriously affecting the service life of the recycled pavement. Summary of the Invention

[0003] In view of the defects or deficiencies of the prior art, the present invention provides a method for preparing emulsified asphalt mortar.

[0004] Therefore, the method for preparing emulsified asphalt mastic provided by the present invention includes: mixing component I and a silane coupling agent to obtain a combined liquid, wherein the mass ratio of component I to the silane coupling agent is 1:0.7 to 1.2;

[0005] The combined liquid and cement are added to the emulsified asphalt and mixed evenly. The amount of the combined liquid added accounts for 0.5 to 2 wt% of the mass of the emulsified asphalt, and the amount of cement added accounts for 30 wt% to 40 wt% of the mass of the emulsified asphalt.

[0006] The raw materials for preparing component I, by weight, include: 8-11 parts methyl allyl polyoxyethylene ether, 1-2.5 parts ascorbic acid, 2-4 parts maleic acid-acrylic acid copolymer, 1.5-4 parts mercaptopropionic acid, 2-3 parts ammonium persulfate, and 75-85 parts water; the preparation method of component I includes:

[0007] A portion of solution A was added to an aqueous solution of methyl allyl polyoxyethylene ether at 60±5℃, followed by the amount of ammonium persulfate specified in the formula, and then the remaining amount of solution A was added. Solution B was then added, with the time taken for adding solution B being longer than the sum of the times taken for adding solution A in the two additions. The solution was then kept at 60±5℃. After keeping at 60±5℃, the pH was adjusted to 6-7 when the solution was cooled to 40±5℃ to obtain solution C. Water was added to solution C and mixed well to obtain component I.

[0008] Solution A is an aqueous solution of ascorbic acid; solution B is an aqueous solution of maleic acid-acrylic acid copolymer and mercaptopropionic acid.

[0009] Alternatively, the silane coupling agent may be selected from one or a mixture of two or more of KH550, KH560, KH570, KH590 and KH792.

[0010] An alternative is to use a peristaltic pump to add solution B.

[0011] An alternative is to control the time taken to add solution B to be 0.5 hours longer than the sum of the times taken to add solution A twice.

[0012] An optional solution is to keep the heat for 0.5 to 1.5 hours.

[0013] This invention also provides a method for preparing emulsified asphalt cold recycled mixture, which includes mixing the emulsified asphalt slurry prepared by the above method with RAP. Optionally, the amount of emulsified asphalt slurry in the emulsified asphalt cold recycled mixture is 4.5 wt% to 6.5 wt%.

[0014] Emulsified asphalt mastic and reclaimed pavement (RAP) are two key materials in cold recycled pavements. Besides their inherent properties, the interaction between their interfaces significantly impacts the pavement mixture. During the RAP coating process, the emulsified asphalt mastic is directly affected by the RAP, primarily due to the presence of aged asphalt on the RAP surface. This weakens the bond between the RAP and the emulsified asphalt mastic, leading to asphalt detachment from the RAP surface during service and causing pavement damage. This invention treats the emulsified asphalt by mixing and adding a self-made component, silane coupling agent, and cement in the correct proportions. The treated emulsified asphalt mastic significantly improves its workability and dispersion, making it easier to apply during subsequent RAP coating and increasing its utilization rate. Attached Figure Description

[0015] Figure 1 This is a standard curve diagram of phenol-saffron red dye solution in an embodiment of the present invention. Detailed Implementation

[0016] Unless otherwise specified, the scientific and technical terms used in this article are intended for understanding by those skilled in the art.

[0017] The present invention will be further described in detail below with reference to the embodiments. It should be noted that the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer.

[0018] The reagents and raw materials used in this invention can all be obtained through conventional channels. Unless otherwise specified, the reagents and raw materials used in this invention shall be used in accordance with conventional methods in the art or according to the product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the methods of this invention. The preferred embodiments and materials described in this invention are for illustrative purposes only. The cement used in this invention is not limited; silicate cement, sulfoaluminate cement, and ordinary silicate cement, etc., can be selected.

[0019] The emulsified asphalt used in the following examples is a slow-cracking cationic emulsified asphalt prepared from 90# base asphalt using a colloid mill. Its basic properties were tested according to the standard "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20~2011), as shown in Table 1. The RAP material used came from the asphalt surface layer of a major and medium-sized road maintenance section. The old asphalt surface layer crushed material was washed, dried, heated, crushed again, and then sieved and graded into five grades: 0–0.6 mm, 0.6–2.36 mm, 2.36–4.75 mm, 4.75–9.5 mm, and 9.5–19 mm. RAP with a particle size in the range [9.5, 4.75) was used.

[0020] Table 1 Basic Properties of Emulsified Asphalt

[0021]

[0022] Example 1:

[0023] The preparation method of emulsified asphalt mortar in this embodiment is as follows: Component I and silane coupling agent KH550 are mixed at a mass ratio of 1:1 to obtain a combined liquid; 1.4 wt% of the combined liquid is added to the emulsified asphalt, and cement accounting for 37.5 wt% of the emulsified asphalt is gradually added under stirring. The mixture is placed under a shearing machine and stirred evenly to obtain modified emulsified asphalt mortar.

[0024] Component I of this embodiment is made from the following raw materials: 8.1 parts of methyl allyl polyoxyethylene ether, 1.4 parts of ascorbic acid, 2.7 parts of maleic acid-acrylic acid copolymer, 2.7 parts of mercaptopropionic acid, 2.1 parts of ammonium persulfate, and 83 parts of water; the specific preparation method is as follows:

[0025] (1) Mix ascorbic acid and water at a ratio of 1:1.5 to prepare solution A; mix maleic acid-acrylic acid copolymer, mercaptopropionic acid and water at a mass ratio of 1:1:2 to prepare solution B;

[0026] (2) Mix methyl allyl polyoxyethylene ether and water at a mass ratio of 1:1.2 and place them in a constant temperature water bath at 60°C and stir to dissolve. After the methyl allyl polyoxyethylene ether is completely dissolved, first add part of solution A drop by drop, then add ammonium persulfate, and then continue to add the remaining solution A drop by drop.

[0027] (3) Slowly add solution B to the solution obtained in step (2) using a peristaltic pump, and control the addition rate so that the addition time of solution B is 0.5 hours longer than that of solution A;

[0028] (4) The solution obtained in step (3) is kept at 60℃ for 1 hour, then cooled to 40℃, and sodium hydroxide is added to neutralize the pH value (adjusted to about 6-7) to finally obtain solution C.

[0029] (5) Add the remaining mass fraction of water to solution C to adjust the solid content, and the self-made component solution is obtained.

[0030] The emulsified asphalt mortar prepared in this example was then mixed with RAP at a dosage of 5.2 wt% in the emulsified asphalt cold recycled mixture to obtain the emulsified asphalt cold recycled mixture.

[0031] Example 2:

[0032] The difference between this embodiment and Embodiment 1 above is that the raw materials of component I are: 9.3 parts of methyl allyl polyoxyethylene ether, 1.5 parts of ascorbic acid, 3.1 parts of maleic acid acrylic acid copolymer, 3.1 parts of mercaptopropionic acid, 2.3 parts of ammonium persulfate, and 80.7 parts of water.

[0033] Example 3:

[0034] The difference between this embodiment and Example 1 is that component I and silane coupling agent are mixed at a mass ratio of 1:1.2 to obtain a combined solution; and the raw materials of component I are: 9.3 parts of methyl allyl polyoxyethylene ether, 1.5 parts of ascorbic acid, 3.1 parts of maleic acid acrylic acid copolymer, 3.1 parts of mercaptopropionic acid, 2.3 parts of ammonium persulfate, and 80.7 parts of water.

[0035] Example 4:

[0036] The difference between this embodiment and Embodiment 1 above is that component I and silane coupling agent are mixed at a mass ratio of 1:1.2 to obtain a combined liquid; the amount of the combined liquid added accounts for 1.8 wt% of the mass of emulsified asphalt, and the amount of cement added accounts for 37.5 wt% of the mass of emulsified asphalt.

[0037] Furthermore, the raw materials for component I are: 9.3 parts of methyl allyl polyoxyethylene ether, 1.5 parts of ascorbic acid, 3.1 parts of maleic acid acrylic acid copolymer, 3.1 parts of mercaptopropionic acid, 2.3 parts of ammonium persulfate, and 80.7 parts of water.

[0038] Comparative Example 1:

[0039] The difference between this comparative example and Example 3 is that component I was not added.

[0040] Comparative Example 2:

[0041] The difference between this comparative example and Example 3 is that no silane coupling agent was added.

[0042] Comparative Example 3:

[0043] The difference between this comparative example and Example 3 is that no component I and silane coupling agent were added; only cement was added.

[0044] Comparative Example 4:

[0045] The difference between this comparative example and Example 3 is that the cement and other materials were replaced with limestone powder.

[0046] Comparative Example 5:

[0047] This comparative example differs from Example 3 in that maleic acid-acrylic acid copolymer was not added to component I. Solution B was prepared from mercaptopropionic acid and water.

[0048] Comparative Example 6:

[0049] The difference between this comparative example and Example 3 is that methyl allyl polyoxyethylene ether was not added to component I. In step (2), part of solution A was added to constant temperature water at 60°C, followed by the addition of ammonium persulfate, and then the remaining solution A was added dropwise. The rest of the steps were the same as in Example 3.

[0050] Comparative Example 7:

[0051] The difference between this comparative example and Example 3 is that only maleic acid acrylic copolymer and methyl allyl polyoxyethylene ether are added to component I. Solution A is water, and ammonium persulfate is not added in step (2); solution B is prepared from maleic acid acrylic copolymer and water; the remaining steps are the same as in Example 3.

[0052] Comparative Example 8:

[0053] The difference between this comparative example and Example 3 is that maleic acid acrylic copolymer and methyl allyl polyoxyethylene ether were not added to component I. Solution B was prepared by mercaptopropionic acid and water; in step (2), part of solution A was added to water at a constant temperature of 60°C, followed by the addition of ammonium persulfate, and then the remaining solution A was added dropwise; the remaining steps were the same as in Example 3.

[0054] Comparative Example 9:

[0055] The difference between this comparative example and Example 3 is that the preparation steps of component I in this comparative example are as follows:

[0056] Add methyl allyl polyoxyethylene ether, maleic acid acrylic copolymer, mercaptopropionic acid and ammonium persulfate to 28.9 parts of water, mix well, and prepare the first solution;

[0057] Add ascorbic acid to 12.4 parts of water, mix well, and prepare a second solution.

[0058] Add the remaining water to the reactor, adjust the reaction temperature to 25℃, and start stirring. First, add the second solution dropwise for 10 minutes, then add the first and second solutions dropwise simultaneously for 120 minutes. After the first solution is finished being added, continue adding the second solution dropwise for 30 minutes. The addition time is 120 minutes for the first solution and 160 minutes for the second solution. After the addition is finished, continue the reaction for 2 hours. Finally, add a 40% sodium hydroxide solution to neutralize and adjust the pH value to about 6-7.

[0059] Viscosity tests, spreadability tests, and coating rate tests were conducted on the above-described embodiments and comparative examples respectively:

[0060] Viscosity test: The Brinell viscometer was used for the test. The emulsified asphalt slurry was loaded into the test cylinder of the Brinell viscometer and the rotor was suspended vertically above the test cylinder. Data was recorded when the torque was 10% to 90%. The entire test process was completed within 3 minutes. Each group of tests was conducted three times and the average value was taken. The test results are shown in Table 3.

[0061] Spreadability Test: The spreadability was determined using a standard consistency meter for emulsified asphalt. During the test, the smaller end of the truncated cone was placed face down on a metal plate. The sample to be tested was then loaded and leveled with a scraper. The standard consistency meter's metal plate was then placed in the center, covering the larger end of the truncated cone. The cone was then inverted so that its larger end was facing down and upright on the metal plate. The cone was then quickly lifted, allowing the emulsified asphalt to flow naturally. After the emulsified asphalt stopped flowing, it formed a circle. The maximum diameter of the two perpendicular flowing circles was measured with a ruler, and the average value was taken as the spreadability. The test results are shown in Table 3.

[0062] The coating rate of emulsified asphalt mastic to RAP was tested using photoelectric colorimetry. The test results are shown in Table 3. The test steps are as follows:

[0063] (1) Take 100g of each of the emulsified asphalt cold recycled mixtures prepared in the above examples and comparative examples and put them into the corresponding containers for testing;

[0064] (2) Dilute with water to prepare a series of phenol-saffron dye solutions of various concentrations, measure the absorbance of the standard solutions, and plot the phenol-saffron dye standard curve, such as... Figure 1 As shown;

[0065] (3) Add 200 mL of phenol-saffron dye solution (0.01 mg / ml) to each sample container in step (1), and then incubate all samples at 60 °C for 2 h.

[0066] (4) Take 25 mL of each sample after the incubation in step (3) and put it into different cuvettes. Use a UV-Vis spectrophotometer to detect the absorbance of each sample. Then find the corresponding concentration of phenol-saffron dye solution on the standard curve and calculate the coating rate of each sample of blue gum paste on RAP using the formula in Table 2.

[0067] Table 2. Steps for calculating coverage rate

[0068]

[0069] Table 3. Test results of sample viscosity, spread, and coating rate.

[0070] Group Viscosity / mPa·s Expansion / mm Coverage rate / % Example 1 3.546 157 91.84 Example 2 3.239 179 93.37 Example 3 3.057 216 95.83 Example 4 2.634 235 94.07 Comparative Example 1 4.943 - 80.81 Comparative Example 2 3.168 203 77.64 Comparative Example 3 5.054 - 75.57 Comparative Example 4 4.232 139 72.36 Comparative Example 5 3.113 209 89.48 Comparative Example 6 4.876 - 82.45 Comparative Example 7 4.787 - 82.13 Comparative Example 8 4.911 - 81.88 Comparative Example 9 3.159 205 90.27

[0071] As can be seen from the test results in Table 3, by comparing Examples 1-4, it can be seen that increasing the solid content of the self-made component can reduce the viscosity of the emulsified asphalt mortar and increase its spreadability, indicating that the present invention can increase the fluidity of the emulsified asphalt mortar; the different mass ratios of the self-made component I and the silane coupling agent significantly improve the coating rate, and the resulting emulsified asphalt mortar has a strong coating ability for RAP.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. All other embodiments obtained without creative effort should be included within the protection scope of the present invention.

Claims

1. A method for preparing emulsified asphalt mortar, characterized in that, The method includes: mixing component I and a silane coupling agent to obtain a combined solution, wherein the mass ratio of component I to the silane coupling agent is 1:0.7~1.2; The combined liquid and cement are added to the emulsified asphalt and mixed thoroughly. The amount of the combined liquid added is 0.5-2 wt% of the mass of the emulsified asphalt, and the amount of cement added is 30-40 wt% of the mass of the emulsified asphalt. The raw materials for preparing component I, by weight, include: 8-11 parts methyl allyl polyoxyethylene ether, 1-2.5 parts ascorbic acid, 2-4 parts maleic acid-acrylic acid copolymer, 1.5-4 parts mercaptopropionic acid, 2-3 parts ammonium persulfate, and 75-85 parts water; the preparation method of component I includes: Add a portion of solution A to an aqueous solution of methyl allyl polyoxyethylene ether at 60±5℃, then add the prescribed amount of ammonium persulfate, followed by the remaining amount of solution A; then add solution B, ensuring that the time taken to add solution B is longer than the sum of the two times solution A is added; after this, keep the solution at 60±5℃; after cooling to 40±5℃, adjust the pH to 6~7 to obtain solution C; add water to solution C and mix well to obtain component I; Solution A is an aqueous solution of ascorbic acid; solution B is an aqueous solution of maleic acid-acrylic acid copolymer and mercaptopropionic acid.

2. The method for preparing emulsified asphalt mortar according to claim 1, characterized in that, The silane coupling agent is selected from one or a mixture of two or more of KH550, KH560, KH570, KH590 and KH792.

3. The method for preparing emulsified asphalt mortar according to claim 1, characterized in that, Add solution B using a peristaltic pump.

4. The method for preparing emulsified asphalt mortar according to claim 1, characterized in that, The time taken to add solution B was 0.5 hours longer than the sum of the times for adding solution A in two separate additions.

5. The method for preparing emulsified asphalt mortar according to claim 1, characterized in that, Heat preservation time: 0.5~1.5h.

6. A method for preparing emulsified asphalt cold recycled mixture, characterized in that, The method includes: mixing the emulsified asphalt mortar prepared by the method of claim 1 with RAP.

7. The method for preparing emulsified asphalt cold recycled mixture according to claim 6, characterized in that, The emulsified asphalt cement paste content in the emulsified asphalt cold recycled mixture is 4.5wt%~6.5wt%.

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