Activated powder modified cold-mix asphalt mixture and preparation method thereof

Abstract

The application belongs to the technical field of asphalt materials, and discloses an activated rubber powder modified cold-mixed asphalt mixture and a preparation method thereof.The activated rubber powder modified cold-mixed asphalt mixture comprises emulsified asphalt, activated rubber powder, aggregate and filler, wherein the mass ratio of the activated rubber powder to the asphalt component in the emulsified asphalt is (0.10-0.20):1; the activated rubber powder comprises rubber powder and epoxidized C5 petroleum resin, and the activated rubber powder is prepared by mixing the rubber powder and the epoxidized C5 petroleum resin and then performing microwave irradiation and activation.The application improves the problem of insufficient compatibility of the rubber powder and the asphalt in the cold-mixed mixture, and the obtained mixture has good strength and stability.

Description

Technical Field

[0001] This invention belongs to the field of asphalt material technology, specifically relating to an activated rubber powder modified cold-mix asphalt mixture and its preparation method. Background Technology

[0002] In the course of social development, with increasing environmental protection requirements and demands for the resource utilization of solid waste, the application of waste tire rubber powder to asphalt pavement has become an important direction for solid waste utilization. Cold-mix asphalt mixtures, due to their convenient construction and energy-saving and environmentally friendly characteristics, are particularly suitable for modification with rubber powder. However, the current technology of directly adding ordinary rubber powder into cold-mix systems has serious drawbacks: at room temperature, the compatibility between rubber powder and emulsified asphalt is extremely poor, and the interfacial bond between the two is weak, resulting in low strength and insufficient durability of the mixed asphalt mixture, severely restricting its application in high-grade pavements. Therefore, rubber powder is generally added to hot-mix asphalt to ensure compatibility between the rubber powder and asphalt.

[0003] In the field of cold-mix asphalt mixtures, current research attempts to add various compatibilizers to improve the compatibility between rubber powder and asphalt. However, the use of these compatibilizers is mostly physical mixing, which cannot build a stable and strong chemical bridge between rubber powder and asphalt. Therefore, how to overcome the interface bottleneck between rubber powder and asphalt, transform waste rubber powder from an "inert filler" into an "active reinforcing component," and establish a suitable performance verification system has become a key challenge in this field to achieve high-performance cold-mix rubber powder modified asphalt technology. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide an activated rubber powder modified cold-mix asphalt mixture and its preparation method, thereby improving the insufficient compatibility between rubber powder and asphalt in cold-mix asphalt mixtures, and resulting in a mixture with good strength and stability.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides an activated rubber powder modified cold-mix asphalt mixture, comprising emulsified asphalt, activated rubber powder, aggregates and fillers, wherein the mass ratio of activated rubber powder to asphalt component in emulsified asphalt is (0.10~0.20):1;

[0007] The activated rubber powder includes rubber powder and epoxidized C5 petroleum resin. The activated rubber powder is obtained by mixing the rubber powder and epoxidized C5 petroleum resin and then activating them by microwave irradiation.

[0008] Preferably, in the activated rubber powder, the mass ratio of epoxidized C5 petroleum resin to rubber powder is (0.08~0.15):1.

[0009] Preferably, the emulsified asphalt is a slow-cracking type emulsified asphalt.

[0010] More preferably, the mass ratio of emulsified asphalt to aggregate is (0.10~0.15):1.

[0011] Preferably, the mass ratio of filler to aggregate is (0.02~0.03):1.

[0012] Preferably, the aggregate is an alkaline aggregate, which includes one or more of limestone, basalt and diabase.

[0013] Preferably, the filler includes one or more of limestone powder, cement, and hydrated lime.

[0014] In a second aspect, the present invention provides a method for preparing activated rubber powder modified cold-mix asphalt mixture, comprising the following steps:

[0015] (1) Rubber powder is mixed with epoxidized C5 petroleum resin and subjected to microwave irradiation to obtain activated rubber powder.

[0016] (2) The aggregate, filler, activated rubber powder and emulsified asphalt are mixed to obtain activated rubber powder modified cold-mix asphalt mixture.

[0017] Preferably, in step (1), the process parameters for microwave irradiation are: the microwave irradiation temperature is 190~220℃, and the microwave irradiation time is 5~15 min.

[0018] Preferably, in step (1), the method for preparing the epoxidized C5 petroleum resin is as follows:

[0019] Add 100 parts by weight of C5 petroleum resin and 20 parts by weight of formic acid, stir and heat to 70°C.

[0020] Subsequently, 30 parts of hydrogen peroxide with a mass concentration of 30% were slowly added dropwise, and the dropping rate was controlled to maintain the reaction temperature at 70°C.

[0021] After the addition is complete, keep the mixture warm for another 5 hours. After the reaction is complete, cool the mixture and neutralize it with an alkaline solution (such as sodium hydroxide solution, concentration is not limited) until it is neutral. Then wash it several times with hot water to remove residual acid and catalyst.

[0022] The organic layer was separated and dehydrated under reduced pressure to obtain epoxidized C5 petroleum resin.

[0023] Preferably, in step (2), the aggregate and filler are first dry-mixed evenly, then activated rubber powder is added and stirred, and finally emulsified asphalt is added and stirred to obtain activated rubber powder modified cold-mix asphalt mixture.

[0024] Beneficial effects:

[0025] This invention activates rubber powder and establishes chemical bonds between the rubber powder and resin through microwave irradiation, effectively improving the poor interfacial compatibility between rubber powder and asphalt in cold-mix asphalt systems and enhancing the overall mechanical strength and long-term durability of the mixture. This invention utilizes waste tire rubber powder as the main raw material, achieving solid waste utilization; the cold-mix process also contributes to energy conservation and economic efficiency. Detailed Implementation

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, specific implementation methods of the present invention will be described below. Obviously, the following descriptions are merely some embodiments of the present invention; those skilled in the art can obtain other implementation methods based on these embodiments without creative effort.

[0027] This invention proposes an activated rubber powder modified cold-mix asphalt mixture, comprising emulsified asphalt, activated rubber powder, aggregates, and fillers. The activated rubber powder comprises rubber powder and epoxidized C5 petroleum resin. The rubber powder and epoxidized C5 petroleum resin are mixed and activated by microwave irradiation to obtain the activated rubber powder. The mass ratio of activated rubber powder to asphalt component in the emulsified asphalt is (0.10~0.20):1, the mass ratio of emulsified asphalt to aggregates is (0.10~0.15):1, and the mass ratio of fillers to aggregates is (0.02~0.03):1.

[0028] Epoxidized C5 petroleum resin refers to a reactive resin in which epoxy groups are introduced into the molecular backbone of C5 petroleum resin. Preferred epoxidized C5 petroleum resins have an epoxy-terminated structure. The C5 backbone of epoxidized C5 petroleum resin exhibits excellent compatibility with asphalt, while the epoxy groups at both ends serve as highly reactive reaction sites.

[0029] The rubber powder is preferably vulcanized rubber powder, such as waste tire rubber powder. Using waste tire rubber powder not only achieves high-value resource utilization of solid waste and reduces raw material costs, but also provides an ideal reaction matrix for microwave activation and subsequent chemical bonding due to its unique cross-linked network structure. This invention achieves the recycling of waste tire rubber powder through activation treatment, and the activated waste tire rubber powder can be directly applied to cold-mix asphalt mixtures. Compared with the conventional method of hot-mixing rubber powder with asphalt, this invention effectively simplifies the recycling operation and helps reduce recycling costs.

[0030] In this invention, the asphalt component content in the emulsified asphalt is generally 50-70%, such as 60%, and the activated rubber powder mainly acts on the asphalt component of the emulsified asphalt.

[0031] In this invention, the activated rubber powder is obtained by microwave irradiation activation treatment of rubber powder. During this process, an interfacial chemical bonding reaction occurs between the rubber powder and the epoxidized C5 petroleum resin to form a composite modified material. The microwave irradiation method in the activated rubber powder has the following effects: on the one hand, its selective heating effect can effectively break the sulfur crosslinking bonds on the surface of the rubber powder (i.e., desulfurization), exposing new active groups (such as thiol groups, carboxyl groups, and free radicals); on the other hand, the heat energy provided drives the epoxy groups to undergo ring-opening addition and other chemical reactions with these active groups, thereby constructing a strong covalent bond bridge between the rubber powder and the resin.

[0032] The rubber powder component in the activated rubber powder of the present invention is compatible with emulsified asphalt at room temperature, and the epoxidized C5 petroleum resin can also improve the compatibility between the activated rubber powder and emulsified asphalt.

[0033] Furthermore, in the activated rubber powder, the mass ratio of epoxidized C5 petroleum resin to rubber powder is (0.08~0.15):1. Epoxidized C5 petroleum resin helps activate the rubber powder, but excessive use of epoxidized C5 petroleum resin in cold-mix asphalt mixtures can have a negative impact on the system. The amount of epoxidized C5 petroleum resin in the activated rubber powder is extremely low, utilizing epoxidized C5 petroleum resin to enhance the performance of the activated rubber powder while avoiding negative impacts on the performance of the cold-mix asphalt mixture.

[0034] The amount of activated binder powder used is related to the asphalt component content in the emulsified asphalt. Preferably, the emulsified asphalt is a slow-cracking type, which has sufficient demulsification time, providing ample mixing, transportation, and construction operation window for the mixture system containing activated binder powder, ensuring that the components in the mixture are uniformly dispersed and effectively combined.

[0035] Preferably, the aggregate is alkaline aggregate, containing alkaline oxides, which can generate strong chemical adsorption and bonding with the acidic components in emulsified asphalt, synergistically enhancing the overall adhesion and water damage resistance of the mixture. More preferably, the alkaline aggregate includes one or more of limestone, basalt, and diabase. Limestone's main component is calcium carbonate, which has excellent adhesion to emulsified asphalt. Basalt and diabase are basic igneous rocks with stable and wear-resistant surface properties, are readily available, and have controllable costs.

[0036] Preferably, the filler includes one or more of limestone powder, cement, and hydrated lime. Limestone powder is a conventional inert filler, mainly serving to fill and improve gradation; cement can undergo a hydration reaction in the presence of water, improving early strength and overall stability; hydrated lime (mainly calcium hydroxide) has high activity and strong alkalinity, which can significantly improve the asphalt-aggregate interface properties and enhance the anti-stripping properties of the mixture. One or more fillers can be selected individually or used in combination according to engineering performance requirements to achieve an optimal balance between function and economy.

[0037] This invention also proposes a method for preparing activated rubber powder modified cold-mix asphalt mixture, comprising the following steps:

[0038] (1) Rubber powder is mixed with epoxidized C5 petroleum resin and subjected to microwave irradiation to obtain activated rubber powder.

[0039] (2) The aggregate, filler, activated rubber powder and emulsified asphalt are mixed to obtain activated rubber powder modified cold-mix asphalt mixture.

[0040] Preferably, in step (1), the process parameters for microwave irradiation are: the microwave irradiation temperature is 190~220℃, and the microwave irradiation time is 5~15 min. The temperature parameter of this invention is one of the key process parameters. Within this temperature range, the crosslinking density of the rubber powder decreases, the sol content increases, and selective chain scission occurs. If the temperature is too high, it will lead to main chain degradation or surface carbonization, affecting the modification effect.

[0041] Preferably, in step (2), the aggregate and filler are first dry-mixed evenly, then activated rubber powder is added and mixing continues, and finally emulsified asphalt is added and mixed to obtain activated rubber powder modified cold-mix asphalt mixture. The activated rubber powder is mixed evenly with the filler and aggregate, so that the surface of the filler and aggregate is first covered with activated rubber powder, and the emulsified asphalt is added last and mixed evenly to ensure the performance of the mixture.

[0042] The technical solution of the present invention will be described in detail below with specific embodiments.

[0043] Example 1

[0044] (1) Weigh 10 parts by weight of 40-mesh waste tire rubber powder (vulcanized rubber) and 1.0 part of epoxy-terminated C5 petroleum resin (epoxy value 0.12 mol / 100g), and dry mix them at room temperature for 3 minutes in a high-speed mixer. Transfer the uniformly mixed material to an industrial microwave reactor. Control the microwave irradiation process to make the core temperature of the material reach and stabilize at 195℃, and maintain this constant temperature for 10 minutes. Then discharge and cool to obtain chemically modified activated rubber powder.

[0045] (2) Weigh 86.8 parts of limestone aggregate and 2.0 parts of limestone powder according to AC-13 gradation, add them to the mixing pot and dry mix for 30 seconds. Then, add 1.0 part of activated rubber powder and continue mixing for 60 seconds. Finally, add 10.0 parts of CRS-1 type slow-cracking cationic emulsified asphalt (asphalt component content is 60%) and wet mix for 90 seconds until all materials are evenly coated to obtain a fresh mixture.

[0046] Epoxidized C5 petroleum resin can be prepared by the following method: Add 100 parts by weight of C5 petroleum resin and 20 parts by weight of formic acid, stir, and heat to 70°C. Then, slowly add 30 parts by weight of 30% hydrogen peroxide, controlling the dropping rate to maintain the reaction temperature within the stated range. After the addition is complete, continue the reaction at this temperature for 5 hours. After the reaction is complete, cool the mixture, neutralize it with sodium hydroxide solution to neutral, and then wash it several times with hot water to remove residual acid and catalyst. Separate the organic layer and dehydrate it under reduced pressure to obtain epoxidized C5 petroleum resin. The same applies below.

[0047] Example 2

[0048] (1) Weigh 10 parts by weight of 40-mesh waste tire rubber powder (vulcanized rubber) and 1.5 parts by weight of epoxy-terminated C5 petroleum resin (epoxy value 0.12 mol / 100g), and dry mix them at room temperature for 3 minutes in a high-speed mixer. Transfer the uniformly mixed material to an industrial microwave reactor. Control the microwave irradiation process to make the core temperature of the material reach and stabilize at 205℃, and continue to be treated at this temperature for 8 minutes. Then discharge and cool to obtain chemically bonded modified activated rubber powder.

[0049] (2) By weight, weigh 80.0 parts of basalt aggregate and 2.0 parts of cement according to AC-13 gradation, add them to the mixing pot and dry mix for 30 seconds. Then, add 0.75 parts of activated rubber powder and continue mixing for 60 seconds. Finally, add 10.0 parts of CRS-1 type slow-cracking cationic emulsified asphalt (asphalt component content is 60%) and wet mix for 90 seconds until all aggregates are evenly coated to obtain fresh mixture.

[0050] Example 3

[0051] (1) Weigh 10 parts by weight of 40-mesh waste tire rubber powder (vulcanized rubber) and 1.0 part of epoxy-terminated C5 petroleum resin (epoxy value 0.12 mol / 100g), and dry mix them in a high-speed mixer at 25°C for 3 minutes. Transfer the uniformly mixed material to an industrial microwave reactor. Control the microwave irradiation process to make the center temperature of the material reach and stabilize at 215°C, and continue to be treated at this temperature for 12 minutes. Then discharge and cool to obtain chemically bonded modified activated rubber powder.

[0052] (2) Calculate by weight, weigh 85.0 parts of diabase aggregate according to AC-13 gradation. Separately weigh 2 parts of limestone powder and 0.5 parts of hydrated lime, mix evenly as filler. Add the aggregate and filler to the mixing pot and dry mix for 30 seconds. Then, add 1.0 part of activated rubber powder and continue mixing for 60 seconds. Finally, add 12.0 parts of Span-20 type slow-cracking emulsified asphalt (asphalt component content is 60%), wet mix for 90 seconds until all aggregates are evenly coated, and obtain fresh mixture.

[0053] Comparative Example 1

[0054] The difference from Example 1 is that: without the activation treatment in step (1), an equal amount of ordinary waste tire rubber powder, 4.2 parts by weight, was directly added to step (2) without any treatment.

[0055] Comparative Example 2

[0056] The difference from Example 1 is that the waste tire rubber powder undergoes the same microwave treatment (165°C / 10 minutes) as in Example 1, but without the addition of any petroleum resin. Other formulations and processes are the same as in Example 1.

[0057] Comparative Example 3

[0058] The difference from Example 1 is that an equal amount of epoxidized C5 petroleum resin was added, but it was only physically mixed with the adhesive powder at 25°C without microwave irradiation. Other formulations and processes are the same as in Example 1.

[0059] Comparative Example 4

[0060] The difference from Example 1 is that the same process as in Example 1 is used, but the epoxidized C5 petroleum resin is replaced with an equal amount of ordinary C5 petroleum resin (without epoxy groups). Other formulations and processes are the same as in Example 1.

[0061] Comparative Example 5

[0062] The difference from Example 1 is that a "two-step method" is used to prepare the activated adhesive powder. First, microwave-activated adhesive powder is prepared according to the method in Comparative Example 2, cooled to 25°C, and then physically mixed with epoxidized C5 petroleum resin. That is, "activation first, then mixing." Other formulations and processes are the same as in Example 1.

[0063] Comparative Example 6

[0064] The difference from Example 1 is that 10 parts of 40-mesh waste tire rubber powder (vulcanized rubber) and 3 parts of epoxy-terminated C5 petroleum resin are used. Other formulations and processes are the same as in Example 1.

[0065] Comparative Example 7

[0066] The difference from Example 1 is that the mass ratio of activated rubber powder to the asphalt component in the emulsified asphalt is 0.3:1. Other formulations and processes are the same as in Example 1.

[0067] For rubber powder-emulsified asphalt blends, microwave activation significantly improved their high-temperature deformation resistance, medium-temperature fatigue resistance, and low-temperature crack resistance. The underlying mechanism lies in the fact that activation improves the compatibility between rubber powder and asphalt, especially enhancing the interfacial bonding between the solid particles of rubber powder and the matrix, and improving the adhesion performance between emulsified asphalt and aggregates.

[0068] Performance testing:

[0069] All the compacted specimens of the mixtures prepared in the examples and comparative examples were cured at room temperature (20°C) for 7 days, and the following targeted tests were performed:

[0070] Splitting tensile strength: determined according to the standard method of JTG E20 T0716. At 15℃, a standard cylindrical specimen is placed horizontally between the pressure plates of the testing machine, and a linearly increasing load is applied along the diameter of the specimen through an arc-shaped pressure strip until the specimen splits and fails. The splitting tensile strength (MPa) is calculated from the maximum load at failure, the specimen diameter, and the height using a standard formula. This index directly reflects the overall tensile strength and internal bonding performance of the mixture.

[0071] Immersion splitting strength ratio: The specimen is immersed in a 60℃ water bath for 48 hours, and a splitting strength test is conducted. The ratio of the splitting strength to the dry splitting strength is calculated. This is used to sensitively evaluate the interface's resistance to water damage.

[0072] Freeze-thaw splitting strength ratio: The specimen undergoes a cycle of vacuum saturation, freezing at -18℃ for 16 hours, and water bath at 60℃ for 24 hours. After two cycles, the splitting strength is measured and compared with the strength of the unfrozen specimen. This evaluates the interfacial durability under extreme temperature and humidity conditions.

[0073] Low-temperature bending failure strain: According to JTG E20 T0715 standard, a three-point bending test was conducted at -10℃ with a loading rate of 50 mm / min. The maximum bending tensile strain (με) at specimen failure was recorded. The interface toughness and low-temperature crack resistance were evaluated.

[0074] Rutting test dynamic stability: According to JTG E20 T0719 standard, the test was conducted at 60℃ using a rutting tester on a molded plate-shaped specimen (300mm×300mm×50mm). A rubber wheel was used to reciprocate at a frequency of 42 times / minute, and the rutting depth was measured between 45 and 60 minutes. The dynamic stability (times / mm) was calculated using a formula. This evaluated the high-temperature resistance to deformation.

[0075] The performance test results are shown in Table 1.

[0076] Table 1. Performance test results of the examples and comparative examples.

[0077] .

[0078] Examples 1-3 demonstrate that within the parameter range of this invention, the mixtures prepared by this invention exhibit excellent and stable properties. For cold-mix asphalt mixtures, microwave activation treatment significantly improves high-temperature stability, water stability, and anti-stripping performance. The activated rubber powder can form a stable interfacial bond with the asphalt matrix, synergistically resisting load deformation and moisture erosion, transforming the rubber powder from a filler into an effective structural component. In terms of crack resistance, activation greatly enhances the toughness of the mixture, increasing fracture energy, impact toughness, and fracture toughness, promoting a shift in the failure mode from brittle to ductile, and strengthening the material's ability to inhibit crack propagation.

[0079] The embodiments provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention, and the descriptions of the embodiments above are only for the purpose of helping to understand the core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A cold-mix asphalt mixture modified with activated rubber powder, characterized in that, It includes emulsified asphalt, activated binder powder, aggregates and fillers, wherein the emulsified asphalt is slow-cracked emulsified asphalt, and the mass ratio of activated binder powder to the asphalt component in the emulsified asphalt is (0.10~0.20):1; The activated rubber powder includes rubber powder and epoxidized C5 petroleum resin. The mass ratio of epoxidized C5 petroleum resin to rubber powder is (0.08~0.15):

1. The rubber powder and epoxidized C5 petroleum resin are mixed and then activated by microwave irradiation to obtain the activated rubber powder. The process parameters of microwave irradiation are: microwave irradiation temperature is 190~220℃, and microwave irradiation time is 5~15 min. The preparation method of epoxidized C5 petroleum resin is as follows: Add 100 parts by weight of C5 petroleum resin and 20 parts by weight of formic acid, stir and heat to 70°C. Subsequently, 30 parts of hydrogen peroxide with a mass concentration of 30% were slowly added dropwise, and the dropping rate was controlled to maintain the reaction temperature at 70°C. After the addition is complete, keep the mixture warm and continue the reaction for 5 hours. After the reaction is complete, cool the mixture, neutralize it with alkali solution to neutral, and then wash it several times with hot water to remove residual acid and catalyst. The organic layer was separated and dehydrated under reduced pressure to obtain epoxidized C5 petroleum resin.

2. The activated rubber powder modified cold-mix asphalt mixture according to claim 1, characterized in that, The mass ratio of emulsified asphalt to aggregate is (0.10~0.15):

1.

3. The activated rubber powder modified cold-mix asphalt mixture according to claim 1 or 2, characterized in that, The mass ratio of filler to aggregate is (0.02~0.03):

1.

4. The activated rubber powder modified cold-mix asphalt mixture according to claim 1, characterized in that, The aggregate is alkaline aggregate, which includes one or more of limestone, basalt and diabase.

5. The activated rubber powder modified cold-mix asphalt mixture according to claim 1, characterized in that, The filler includes one or more of limestone powder, cement, and hydrated lime.

6. A method for preparing activated rubber powder modified cold-mix asphalt mixture, characterized in that, The preparation of the activated rubber powder modified cold-mix asphalt mixture according to any one of claims 1-5 includes the following steps: (1) Rubber powder is mixed with epoxidized C5 petroleum resin and subjected to microwave irradiation to obtain activated rubber powder. (2) The aggregate, filler, activated rubber powder and emulsified asphalt are mixed to obtain activated rubber powder modified cold-mix asphalt mixture; In step (1), the method for preparing epoxidized C5 petroleum resin is as follows: Add 100 parts by weight of C5 petroleum resin and 20 parts by weight of formic acid, stir and heat to 70°C. Subsequently, 30 parts of hydrogen peroxide with a mass concentration of 30% were slowly added dropwise, and the dropping rate was controlled to maintain the reaction temperature at 70°C. After the addition is complete, keep the mixture warm and continue the reaction for 5 hours. After the reaction is complete, cool the mixture, neutralize it with alkali solution to neutral, and then wash it several times with hot water to remove residual acid and catalyst. The organic layer was separated and dehydrated under reduced pressure to obtain epoxidized C5 petroleum resin.

7. The preparation method according to claim 6, characterized in that, In step (1), the process parameters for microwave irradiation are: the microwave irradiation temperature is 190~220℃, and the microwave irradiation time is 5~15 min.