Ultra-thin asphalt overlay material made of reactive full RAP material and its construction method

Abstract

The present application provides a reactive all-RAP ultra-thin asphalt overlay material and its construction method, which relates to the field of recycled asphalt mixtures. It includes RAP material, viscosity-increasing regenerant, and interface protectant. The viscosity-increasing regenerant includes base asphalt, epoxy resin, asphalt warm mix agent, and asphalt regenerant. The interface protectant includes hard asphalt, asphalt modifier, and curing agent. The construction method includes: heating the RAP material to 130-140 °C, adding the viscosity-increasing regenerant, and stirring; paving an ultra-thin overlay with a thickness of 1.5-2.5 cm, and performing rolling forming while paving; waiting for the temperature of the just-rolled ultra-thin overlay to drop, evenly spraying the interface protectant on the surface, and waiting for the temperature to drop below 40 °C. The present application uses 100% RAP material, which can produce an ultra-thin overlay with road performance comparable to that of newly mixed mixtures, while ensuring that its road performance is not lower than that of newly mixed asphalt mixtures with the same gradation, greatly reducing the construction cost of the ultra-thin overlay.

Description

Technical Field

[0001] The present application relates to the field of recycled asphalt mixtures, and particularly to an ultra-thin asphalt overlay material made of reactive full RAP material and its construction method. Background Art

[0002] At present, the utilization of recycled asphalt mixtures mainly focuses on road bases and middle and lower surface layers. The benefit of using them in the base is low, while the benefit is relatively high when used in the middle and lower surface layers, but the addition ratio is generally less than 30%. To ensure quality, recycled asphalt mixtures are rarely used in the upper surface layer of asphalt pavements. Currently, the main work in maintenance projects is in the upper surface layer. Using recycled asphalt mixtures safely and reliably in the surface layer can save a large amount of resources, meeting the requirements of green, low-carbon, and environmental protection in China.

[0003] The ultra-thin asphalt overlay has a small thickness, saves materials, has little impact on elevation, repairs pavement diseases, seals water, resists skidding, reduces noise, and has good durability. It is an important technology for current surface layer maintenance work. However, the ultra-thin asphalt overlay has high requirements for materials. The "Technical Specification for Highway Asphalt Pavement Maintenance (JTG 5142-2019)" stipulates that the softening point of the high-viscosity modified asphalt used in the ultra-thin asphalt overlay is higher than 75°C, and the high-toughness ultra-thin overlay technology even requires the softening point of the modified asphalt to be higher than 90°C. In terms of aggregates, it is generally required to select strong and wear-resistant aggregates. For highway asphalt pavements, the crushing value of coarse aggregates for expressways and first-class highways should be lower than 26, and the ultra-thin overlay generally has no lower requirement. Therefore, it is generally difficult to add recycled asphalt mixtures to ultra-thin overlay projects, which will inevitably have a negative impact on the future popularization and application of ultra-thin overlay technology. Summary of the Invention

[0004] In order to improve the problem that recycled asphalt mixtures cannot be used in the current ultra-thin asphalt overlay, the present application provides an ultra-thin asphalt overlay material made of reactive full RAP material and its construction method.

[0005] In the first aspect, the present application provides an ultra-thin asphalt overlay material made of reactive full RAP material, adopting the following technical solution:

[0006] An ultra-thin asphalt overlay material made of reactive full RAP material, comprising RAP material, a viscosity-increasing regenerant, and an interface protector.

[0007] The viscosity-increasing regenerant comprises matrix asphalt, epoxy resin, an asphalt warm mix agent, and an asphalt regenerant, and the mass ratio of the matrix asphalt, the epoxy resin, the asphalt warm mix agent, and the asphalt regenerant is 16-24:2-5:1-2:6-10.

[0008] The interface protector comprises hard asphalt, an asphalt modifier, and a curing agent, and the mass ratio of the hard asphalt, the asphalt modifier, and the curing agent is 100:1-2:10-20.

[0009] Optionally, the curing agent is an amine curing agent.

[0010] Optionally, the curing agent includes at least one of isophorone diamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

[0011] Optionally, the matrix asphalt is 70# road petroleum asphalt or 90# road petroleum asphalt.

[0012] Optionally, the asphalt warm mix additive is the Evothem product of Ingevity Corporation, model M1.

[0013] Optionally, the asphalt rejuvenator is the Evoflex product of Ingevity Corporation.

[0014] Optionally, the epoxy resin is E51 type epoxy resin.

[0015] Optionally, the asphalt modifier includes one or two of SBS and SBR.

[0016] Optionally, the hard asphalt is 50# petroleum asphalt.

[0017] Optionally, the interface protective agent further includes a diluent, and the mass ratio of the hard asphalt to the diluent is 1:1 - 1.5.

[0018] Optionally, the diluent is octane.

[0019] Optionally, the interface protective agent is prepared by the following preparation method:

[0020] Heat the hard asphalt to 160 - 170°C, add the asphalt modifier, carry out high-speed shearing, then keep stirring at this temperature for 3 - 4 h until the asphalt modifier is fully swollen, then lower the temperature of the mixture to 120 - 140°C, add the curing agent and the diluent, stir for 15 min, and cool to room temperature to obtain it.

[0021] Optionally, the rate of the high-speed shearing is 5000 - 6000 r / min, and the time is 30 min.

[0022] In a second aspect, the present application provides a construction method for an ultra-thin asphalt overlay material, adopting the following technical solution:

[0023] A construction method for an ultra-thin asphalt overlay material includes the following steps:

[0024] Step S1: Heat the RAP material to 130 - 140°C, add the viscosity-increasing rejuvenator, and stir for 20 - 30 s to obtain an asphalt mixture;

[0025] Step S2: Spread the asphalt mixture into a 1.5 - 2.5 cm thick ultra - thin overlay according to the designed thickness of the ultra - thin overlay, and perform rolling and forming simultaneously during spreading.

[0026] Step S3: Wait for the temperature of the just - rolled ultra - thin overlay to drop to 70 - 80 °C, evenly spray the interface protective agent onto the surface, and wait for the temperature to drop below 40 °C before opening to traffic.

[0027] Optionally, in step S1, the mass ratio of the RAP material to the viscosity - increasing regenerant is 100:0.5 - 1.

[0028] Optionally, in step S1, the discharge temperature of the asphalt mixture is not lower than 135 °C.

[0029] Optionally, in step S2, the initial rolling temperature shall not be lower than 125 °C, and the final rolling temperature is 100 - 110 °C.

[0030] Optionally, in step S3, the dosage of the interface protective agent is 0.2 kg / m 2 - 0.3 kg / m 2 .

[0031] Optionally, in step S3, when the thickness of the ultra - thin overlay is 1.5 cm, the dosage of the interface protective agent is 0.2 kg / m 2 , and when the thickness of the ultra - thin overlay is 2.5 cm, the dosage of the interface protective agent is 0.3 kg / m 2 .

[0032] In summary, this application includes at least one of the following beneficial effects:

[0033] 1. By using the viscosity - increasing regenerant and the interface protective agent in combination, especially the epoxy resin in the viscosity - increasing regenerant and the curing agent in the interface protective agent, which can undergo a curing and viscosity - increasing reaction, this application greatly increases the cohesion of the asphalt concrete, improves the strength of the asphalt concrete, and enhances the water - resistance of the asphalt concrete.

[0034] 2. By using 100% RAP material, this application can produce an ultra - thin overlay with road - using performance comparable to that of newly mixed mixtures, while ensuring that its road - using performance is not lower than that of newly mixed asphalt mixtures with the same gradation, greatly reducing the construction cost of the ultra - thin overlay.

[0035] 3. By adding a diluent to the interface protective agent in this application, not only can the interface protective agent have a certain fluidity at room temperature, which is convenient for construction, but also it can promote the rapid penetration of the interface protective agent into the asphalt concrete and promote the full contact between the curing agent and the epoxy resin. After construction, the diluent will volatilize quickly and will not affect the performance of the final interface protective agent.

[0036] 4. In this application, the epoxy resin is placed in the asphalt mixture, while the curing agent is placed in the interface protective agent. The construction is carried out by relying on a two-step construction method. The diluent in the interface protective agent can promote its downward penetration and the contact between the curing agent and the epoxy resin. At the same time, using the residual heat temperature just after paving, the rate of its curing reaction is promoted.

[0037] 5. By using SBS or SBR as the asphalt modifier in this application, the performance of the hard asphalt can be better. By increasing the softening point and improving the low-temperature tensile performance, the wear resistance of the formed oil film can be ultimately improved.

[0038] 6. The construction of the ultra-thin asphalt wearing surface material in this application is simple and convenient, without adding extra time and without affecting the construction efficiency. Detailed Embodiment

[0039] To better understand the above technical solutions, the above technical solutions will be described in detail below in combination with specific embodiments.

[0040] Unless otherwise specified, the materials used in the following examples and comparative examples of the present invention can be obtained through commercial purchase or prepared by conventional methods. The RAP material used in the following examples and comparative examples of this application is the RAP material of the upper surface layer of the road surface; the matrix asphalt used in the following examples and comparative examples of this application is 70# road petroleum asphalt; the epoxy resin used in the following examples and comparative examples of this application is E51 type epoxy resin; the asphalt warm mix agent used in the following examples and comparative examples of this application is the Evothem product of Ingevity Corporation, model M1; the asphalt rejuvenator used in the following examples and comparative examples of this application is the Evoflex product of Ingevity Corporation; the hard asphalt used in the following examples and comparative examples of this application is 50# petroleum asphalt; the diluent used in the following examples and comparative examples of this application is octane.

[0041] Example 1 provides a reaction-type ultra-thin asphalt wearing surface material made of all RAP materials and its construction method, including RAP materials, a viscosity-increasing rejuvenator, and an interface protective agent.

[0042] ① The specific composition of the viscosity-increasing rejuvenator can be seen in Table 1, and its preparation method is operated according to the following steps: The epoxy resin, matrix asphalt, asphalt warm mix agent, and asphalt rejuvenator are mixed in proportion.

[0043] ② The specific composition of the interface protective agent can be seen in Table 1, and its preparation method is operated according to the following steps: Heat the hard asphalt to 170 °C, add the asphalt modifier, carry out high-speed shearing, then keep stirring at this temperature for 3 h until the asphalt modifier is fully swollen, then lower the temperature of the mixture to 130 °C, add the curing agent and the diluent, stir for 15 min, and cool to room temperature to obtain it. Among them, the curing agent is isophorone diamine, and the asphalt modifier is SBS.

[0044] ③ The specific construction method of the ultra-thin asphalt overlay material of this reactive full-RAP material is as follows:

[0045] Step S1: Heat the RAP material to 135 °C, add the prepared tackifier regenerant as above, stir for 30 s to obtain the asphalt mixture. The mass ratio of the RAP material to the tackifier regenerant is 100:0.5, and the discharge temperature of the asphalt mixture is not lower than 135 °C;

[0046] Step S2: Spread a 1.5 cm thick ultra-thin overlay according to the designed thickness of the ultra-thin overlay, and carry out rolling forming while spreading;

[0047] Step S3: Wait for the temperature of the just-rolled ultra-thin overlay to drop to 80 °C, and evenly spray the interface protective agent on the surface. The spraying amount of the interface protective agent is 0.2 kg / m 2 , wait for the temperature to drop below 40 °C, and then the traffic can be opened.

[0048] Table 1 Dosages (kg) of raw materials of the tackifier regenerant and the interface protective agent in each example

[0049]

[0050] Example 2 provides an ultra-thin asphalt overlay material of a reactive full-RAP material and its construction method, which is basically the same as Example 1, except that the dosages of each raw material in the tackifier regenerant and the interface protective agent in Example 2 are different. Specifically, it can be seen in Table 1, and the mass ratio of the RAP material to the tackifier regenerant is 100:1.

[0051] Example 3 provides an ultra-thin asphalt overlay material of a reactive full-RAP material and its construction method, which is basically the same as Example 1, except that the dosages of each raw material in the tackifier regenerant and the interface protective agent in Example 3 are different. Specifically, it can be seen in Table 1; and the mass ratio of the RAP material to the tackifier regenerant is 100:0.5, the paving thickness of the ultra-thin overlay is 2.5 cm, and the spraying amount of the interface protective agent is 0.3 kg / m 2 .

[0052] Example 4 provides a reactive all-RAP ultra-thin asphalt overlay material and its construction method, which is basically the same as Example 1, except that the curing agent in Example 4 is diethylenetriamine.

[0053] Example 5 provides a reactive all-RAP ultra-thin asphalt overlay material and its construction method, which is basically the same as Example 1, except that the asphalt modifier of the interface protector in Example 5 is SBR.

[0054] Comparative Example 1 provides a reactive all-RAP ultra-thin asphalt overlay material and its construction method, which is basically the same as Example 1, except that the paving thickness of the ultra-thin overlay in Comparative Example 1 is 1.5 cm, and the spraying amount of the interface protector is 0.1 kg / m 2 。

[0055] Comparative Example 2 provides a reactive all-RAP ultra-thin asphalt overlay material and its construction method, which is basically the same as Example 1, except that the mass ratio of the RAP material to the viscosity-increasing regenerant in Comparative Example 2 is 100:0.2.

[0056] Comparative Example 3 provides a reactive all-RAP ultra-thin asphalt overlay material and its construction method, which is basically the same as Example 1, except that there is no epoxy resin in the viscosity-increasing regenerant of Comparative Example 3.

[0057] Comparative Example 4 provides a reactive all-RAP ultra-thin asphalt overlay material and its construction method, which is basically the same as Example 1, except that there is no curing agent in the interface protector of Comparative Example 4.

[0058] According to the test method of T0702-2011 in the "Test Procedures for Bitumen and Bituminous Mixtures for Highway Engineering" (JTG E20-2011), asphalt mixture specimens were made from the asphalt mixtures obtained in the above examples and comparative examples respectively. By calculating the upper surface area of the specimens, the corresponding interface protectors were brushed on the surface of the specimens and allowed to stand and cool to simulate the process of on-site paving and spraying.

[0059] The specific test items are as follows, and the specific test results are shown in Table 2.

[0060] (1) Marshall stability and immersion residual Marshall stability: Standard Marshall stability test and immersion Marshall stability test were carried out according to T0709-2011 in the "Test Procedures for Bitumen and Bituminous Mixtures for Highway Engineering (JTG E20-2011)". The Marshall stability and immersion Marshall stability of the standard specimens were obtained through the test.

[0061] When measuring the Marshall stability, in this application, the Marshall stability of standard specimens cured at normal temperature for 2 h and then kept in a constant temperature water bath at 60 °C for 30 min was measured respectively.

[0062] When measuring the immersion Marshall stability, in this application, the Marshall stability of standard specimens cured at normal temperature for 7 d after being kept in a constant temperature water bath at 60 °C for 30 min and the Marshall stability of standard specimens cured at normal temperature for 7 d after being kept in a constant temperature water bath at 60 °C for 48 h were measured, and the immersion residual Marshall stability was calculated. The immersion residual Marshall stability is equal to the ratio of the immersion Marshall stability (60 °C) to the standard Marshall stability (60 °C). The Marshall stability is used to evaluate the mechanical properties of asphalt mixtures, and the immersion residual Marshall stability is used to evaluate the water stability of asphalt mixtures.

[0063] (2) Dynamic stability: First, the prepared asphalt mixture was rolled into a plate-shaped specimen with a length of 300 mm, a width of 300 mm, and a thickness of 50 mm by a wheel rolling forming machine according to T0703-2011. The corresponding interface protective agent was applied to the surface of the specimen, and it was left to stand and cool to simulate the process of spraying during on-site paving. Then it was placed in an incubator and cured at 60 °C for 7 days. Then, according to T0719-2011 in the "Test Procedures for Bitumen and Bituminous Mixtures for Highway Engineering" (JTG E20—2011), the plate-shaped specimen together with the test mold was placed on a rutting test machine for rutting test. During the test, the recorder automatically recorded the specimen deformation curve and the corresponding specimen temperature. The dynamic stability was calculated according to the calculation formula in Section 4 of T0719-2011. The dynamic stability is used to measure the high-temperature rutting resistance of asphalt mixtures. The requirement should be greater than 6000 times / mm.

[0064] (3) Cantabro loss: The Cantabro loss test of asphalt mixture was carried out according to T0733-2011 in the "Test Procedures for Bitumen and Bituminous Mixtures for Highway Engineering" (JTG E20—2011). The Cantabro loss is used to evaluate the degree of loss of surface aggregates of the road surface due to insufficient asphalt content or adhesiveness under traffic load, which is expressed as the percentage of the mass of the scattered material of the asphalt mixture specimen after the Marshall specimen rotates a specified number of times in the Los Angeles testing machine.

[0065] Table 2 Performance test results

[0066]

[0067] It can be seen from the results in Table 2 that after the construction of the ultra-thin asphalt overlay materials provided in Examples 1-5, due to the curing and viscosity-increasing reaction between the epoxy resin in the viscosity-increasing regenerant and the curing agent in the interface protective agent, the strength and water resistance of the asphalt concrete are greatly improved.

[0068] Compared with Example 1, in Comparative Example 1, since the spraying amount of the interface protective agent is only half of that in Example 1, the content of the curing agent is also only half of that in Example 1. A large amount of curing agent in Example 1 can fully react with the epoxy resin in the tackifier regenerant, greatly increasing the cohesion of the asphalt concrete, so that its mechanical properties and water resistance are much higher than those in Comparative Example 1.

[0069] Compared with Example 1, in Comparative Example 2, due to the insufficient amount of the tackifier regenerant, the amount of epoxy resin reacting with the curing agent in the interface protective agent is also less. A large amount of curing agent in Example 1 can fully react with the epoxy resin in the tackifier regenerant, greatly increasing the cohesion of the asphalt concrete, so that its mechanical properties and water resistance are much higher than those in Comparative Example 2.

[0070] Compared with Example 1, in Comparative Example 3, due to the lack of epoxy resin, and in Comparative Example 4, due to the lack of curing agent, the interface protective agent can only float on the surface of the asphalt concrete and cannot be deeply combined with it. Therefore, its mechanical properties and water resistance are both poor.

[0071] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereby. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A reactive all-RAP ultra-thin asphalt overlay material, characterized in that: Including RAP material, viscosity increasing regeneration agent and interface protective agent, The viscosity increasing regeneration agent comprises base asphalt, epoxy resin, asphalt warm mix agent and asphalt regeneration agent; and the mass ratio of the base asphalt, the epoxy resin, the asphalt warm mix agent and the asphalt regeneration agent is 16-24:2-5:1-2:6-10; The interface protective agent comprises hard asphalt, asphalt modifier and curing agent, and the mass ratio of the hard asphalt, the asphalt modifier and the curing agent is 100:1-2:10-20; The interface protective agent also includes a diluent, and the mass ratio of the hard asphalt to the diluent is 1:1-1.5; The curing agent includes at least one of isophoronediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine; The construction method of the ultra-thin asphalt overlay material of the reactive full RAP material comprises the following steps: Step S1: heating the RAP material to 130-140° C., adding a viscosity increasing regeneration agent, and stirring for 20-30 seconds to obtain an asphalt mixture; Step S2: Spreading the asphalt mixture into an ultra-thin overlay with a thickness of 1.5 to 2.5 cm according to the designed thickness of the ultra-thin overlay, and rolling and forming the mixture at the same time; Step S3: wait for the temperature of the newly rolled ultra-thin cover surface to drop to 70-80°C, spray the interface protective agent evenly on the surface, wait for the temperature to drop below 40°C, and then open to traffic; In the step S1, the mass ratio of the RAP material to the viscosity increasing regeneration agent is 100:0.5-1; In step S3, the amount of the interface protective agent used is 0.2 kg / m 2 -0.3kg / m 2 .

2. The ultra-thin asphalt overlay material of reactive full RAP material according to claim 1, characterized in that: The base asphalt is 70# road petroleum asphalt or 90# road petroleum asphalt.

3. The ultra-thin asphalt overlay material of reactive full RAP material according to claim 1, characterized in that: The asphalt modifier includes one or both of SBS and SBR.

4. The ultra-thin asphalt overlay material of reactive full RAP material according to claim 1, characterized in that: The interface protective agent is prepared by the following preparation method: Heat the hard asphalt to 160-170°C, add the asphalt modifier, perform high-speed shearing, and then maintain the temperature and stir for 3-4 hours until the asphalt modifier is fully swollen, then reduce the temperature of the mixture to 120-140°C, add the curing agent and the diluent, stir for 15 minutes, and cool to room temperature.

5. A construction method for an ultra-thin asphalt overlay material of a reactive full RAP material according to any one of claims 1 to 4, characterized in that: The steps include: Step S1: heating the RAP material to 130-140° C., adding a viscosity increasing regeneration agent, and stirring for 20-30 seconds to obtain an asphalt mixture; Step S2: Spreading the asphalt mixture into an ultra-thin overlay with a thickness of 1.5 to 2.5 cm according to the designed thickness of the ultra-thin overlay, and rolling and forming the mixture at the same time; Step S3: Wait for the temperature of the newly rolled ultra-thin cover surface to drop to 70-80°C, spray the interface protective agent evenly onto the surface, wait for the temperature to drop below 40°C, and then open to traffic.

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