An activator for in-situ foam-temperature recycled mixtures, the in-situ foam-temperature recycled mixture, and its preparation method.

Abstract

This invention relates to the field of road engineering technology, and more particularly to an activator for in-situ foamed warm-mix asphalt mixtures, in-situ foamed warm-mix asphalt mixtures, and their preparation method. The activator includes fatty acid alcohol amide, hexadecyltrimethylammonium bromide, and agar. The in-situ foamed warm-mix asphalt mixture includes waste asphalt mixture, new aggregate, modified asphalt, foaming water, and the activator. This invention combines foamed warm-mix asphalt technology with in-situ thermal recycling technology. By using an activator with a specific composition, it can effectively reduce the interfacial energy between the asphalt and aggregate phases, improve the foaming effect of the foamed modified asphalt, promote the foaming of old asphalt on the surface of the RAP (Rich Asphalt Compound), increase the activation rate of old asphalt, thereby reducing the amount of new asphalt added, and giving the resulting in-situ foamed warm-mix asphalt mixture good road performance and service life.

Description

Technical Field

[0001] This invention relates to the field of road engineering technology, and in particular to an activator for in-situ foam-temperature regenerated mixtures, in-situ foam-temperature regenerated mixtures, and their preparation methods. Background Technology

[0002] Existing recycled asphalt mixtures are made by excavating, recycling, crushing, and screening old asphalt pavements, then remixing them with recycling agents, new asphalt materials, and new aggregates in a certain proportion. They are generally divided into in-situ recycling and plant-mixed recycling. Due to the influence of the road performance of recycled asphalt mixtures, the proportion of old material in the mix is ​​generally less than 30%. Furthermore, the asphalt binder effect is not well restored after adding recycling agents to aged asphalt, and the amount of new asphalt added during recycling is relatively large, resulting in low economic efficiency. The source and properties of recycled asphalt and asphalt mixtures directly affect the performance of the recycled asphalt mixture. Foamed asphalt is generally used in plant-mixed cold recycled mixtures, while hot recycling typically involves adding recycling agents to the old asphalt. Existing in-situ hot recycling technology uses high heating temperatures, resulting in strong secondary aging of asphalt and aggregates, making it difficult to restore the performance of aged asphalt. Moreover, the high heating temperature of the original pavement consumes a lot of energy, and the generated asphalt fumes pose a threat to the environment and construction workers, resulting in very low environmental and social benefits. Summary of the Invention

[0003] In order to solve the above-mentioned technical problems of the present invention, the present invention provides an activator for in-situ foam temperature regeneration mixture, an in-situ foam temperature regeneration mixture and a method for preparing the same.

[0004] According to a first aspect of the present invention, the present invention provides an activator for in-situ foam-temperature regeneration mixtures, comprising fatty acid alcohol amide, hexadecyltrimethylammonium bromide and agar.

[0005] In the above scheme, an activator for in-situ foamed warm recycled asphalt mixtures includes fatty acid alcohol amides, hexadecyltrimethylammonium bromide, and agar. Fatty acid alcohol amides can reduce asphalt cohesiveness and improve the compatibility between asphalt and aggregates. Hexadecyltrimethylammonium bromide is a cationic surfactant with good surface activity, which is beneficial for asphalt foaming. Agar contains polysaccharide molecules, which have cross-linking properties. When agar is mixed with liquids such as water, the polysaccharide molecules absorb the liquid and swell, forming a gel-like substance. Through the synergistic effect of fatty acid alcohol amides, hexadecyltrimethylammonium bromide, and agar, asphalt can be better foamed, and the activation degree of aged asphalt can be improved, resulting in in-situ foamed warm recycled asphalt mixtures with good road performance and service life.

[0006] Further, by weight, the activator comprises 10-20 parts of fatty acid alcohol amide, 5-15 parts of hexadecyltrimethylammonium bromide, and 5-15 parts of agar;

[0007] Preferably, the activator comprises 15 parts by weight of fatty acid alcohol amide, 10 parts by weight of hexadecyltrimethylammonium bromide, and 10 parts by weight of agar.

[0008] In the above scheme, by limiting the amounts of fatty acid alcohol amide, hexadecyltrimethylammonium bromide and agar in the activator to a reasonable range, the components can exert a better synergistic effect, which is more conducive to the foaming of asphalt and the improvement of the activation degree of aged asphalt.

[0009] According to a second aspect of the present invention, the present invention also provides an in-situ foamed warm recycled mixture, comprising waste asphalt mixture (RAP), new aggregate, modified asphalt, foaming water and the above-mentioned activator.

[0010] In the above scheme, foamed warm-mix asphalt technology is based on the foaming properties of asphalt. Foaming water is added to hot asphalt, causing the asphalt volume to expand and reducing its viscosity within a certain time, thereby lowering the construction temperature and improving workability. Furthermore, the foaming medium used in foamed warm-mix asphalt technology is water, a clean and renewable resource, resulting in low production costs and environmental friendliness. In-situ thermal recycling technology is convenient and quick, recycling RAP material in situ and saving on material transportation costs. This invention relates to an in-situ foamed warm-mix asphalt mixture that combines foamed warm-mix asphalt technology with in-situ thermal recycling technology. The in-situ foamed warm-mix asphalt mixture of this invention includes RAP (Rich Acrylic Acid) and new aggregate, as well as waste modified asphalt and foaming water. The modified asphalt, when mixed with foaming water, forms foamed modified asphalt. Based on the theory of convective mass transfer, the foamed modified asphalt has a lower viscosity and a larger specific surface area, allowing it to better integrate with the old asphalt, thereby improving the recovery ability of the old asphalt's properties. Furthermore, the foamed modified asphalt can lower the production temperature of the recycled mixture, allowing for a further increase in the RAP content without increasing the heating temperature of the new aggregate, while ensuring workability and compaction. Previous studies have found that the foaming water used in conventional foamed asphalt cannot foam the old asphalt on the surface of RAP (Rich Asphalt Pavement). Therefore, this invention provides an in-situ foamed warm recycled mixture that includes an activator. The activator effectively reduces the interfacial energy between the asphalt and aggregate phases, improves the foaming effect of the foamed modified asphalt, and promotes complete or partial foaming of the old asphalt on the surface of the RAP, increasing the activation rate of the old asphalt. This reduces the amount of new asphalt needed and results in an in-situ foamed warm recycled mixture with good road performance and service life. This invention's in-situ foamed warm recycled mixture can essentially achieve 100% in-situ recycling of old asphalt pavement materials without generating waste.

[0011] Further, the fatty acid alcohol amide accounts for 1-2% of the modified asphalt, the hexadecyltrimethylammonium bromide accounts for 0.5-1.5% of the modified asphalt, and the agar accounts for 0.5-1.5% of the modified asphalt.

[0012] In the above scheme, by limiting the amount of fatty acid alcohol amide, hexadecyltrimethylammonium bromide and agar in the activator to a reasonable range, it is more conducive to improving the foaming effect of foamed modified asphalt and promoting the foaming of old asphalt on the surface of RAP material.

[0013] Furthermore, the fatty acid alcohol amide accounts for 1.5% of the modified asphalt, the hexadecyltrimethylammonium bromide accounts for 1% of the modified asphalt, and the agar accounts for 1% of the modified asphalt.

[0014] Furthermore, the modified asphalt is SBS modified asphalt.

[0015] In the above scheme, by selecting a suitable type of modified asphalt, the modified asphalt can achieve a better synergistic effect with other components, which is conducive to improving the performance of in-situ foamed warm recycled mixture.

[0016] Furthermore, the weight ratio of the waste asphalt mixture to the new aggregate is (6-8):(2-4), preferably 7:3.

[0017] In the above scheme, by limiting the weight ratio of waste asphalt mixture to new aggregate within a reasonable range, it is beneficial to make full use of waste asphalt mixture while ensuring the performance of in-situ foam-temperature recycled mixture.

[0018] Furthermore, the amount of modified asphalt used is 5%-6% of the new aggregate, preferably 5.3%.

[0019] In the above scheme, by limiting the amount of modified asphalt within a reasonable range, the performance of the in-situ foamed warm recycled mixture can be guaranteed.

[0020] Furthermore, the foaming temperature of the modified asphalt is 150-170℃. Selecting a modified asphalt with a suitable foaming temperature, matching it with the construction temperature of the mixture, ensures that the mixture is evenly distributed on the road surface.

[0021] Furthermore, the amount of foaming water used is 2%-4% of the amount of modified asphalt used.

[0022] In the above scheme, limiting the amount of foaming water to a reasonable range is more conducive to the foaming of modified asphalt.

[0023] According to a second aspect of the present invention, the present invention also provides a method for preparing the above-mentioned in-situ foam-temperature recycled mixture, comprising the following steps:

[0024] The modified asphalt is heated to a molten state, then an activator is added and stirred evenly. The mixture is then heated to the foaming temperature of the modified asphalt (it should be noted that heating is generally not necessary after the foaming temperature is reached). Foaming water is then added to foam the modified asphalt, thus obtaining foamed modified asphalt.

[0025] The obtained foamed modified asphalt is mixed with waste asphalt mixture and new aggregate.

[0026] In the above scheme, the method for preparing in-situ foamed warm recycled asphalt mixture of the present invention first heats the modified asphalt to a molten state, then adds an activator and stirs it evenly. After adding the activator, the mixture is heated to the foaming temperature of the modified asphalt, and then foaming water is added to foam it, thus obtaining foamed modified asphalt. This ensures that the activator and modified asphalt are fully and evenly mixed, which is beneficial to the uniform distribution of the activator in the foamed modified asphalt after foaming. The obtained foamed modified asphalt is mixed with waste asphalt mixture and new aggregate. The activator evenly distributed in the foamed modified asphalt can come into contact with the new aggregate and waste asphalt mixture, better reducing the interfacial energy between the asphalt and aggregate phases, promoting the foaming of the old asphalt on the surface of the RAP material, and improving the activation rate of the old asphalt.

[0027] Furthermore, the mixing temperature is 140-150℃ and the mixing time is 60-80s.

[0028] In the above scheme, by limiting the mixing temperature and time to a reasonable range, the raw materials are fully mixed, and the old asphalt of the RAP material is fully activated.

[0029] Furthermore, the preparation method is implemented using an in-situ recycling device; an asphalt foaming pipe is installed in the asphalt pipeline of the in-situ recycling device, and the foaming water is added to the molten mixture of modified asphalt and activator through the asphalt foaming pipe. Thus, to implement the preparation method of this invention, it is only necessary to replace the original equipment for adding new asphalt in the existing in-situ thermal recycling process with an asphalt foaming device.

[0030] The technical solution provided by this invention has the following beneficial effects:

[0031] This invention discloses an in-situ foamed warm-mix asphalt mixture comprising waste asphalt mixture, new aggregate, modified asphalt, foaming water, and an activator. The activator includes fatty acid alcohol amide, hexadecyltrimethylammonium bromide, and agar. By combining foamed warm-mix asphalt technology with in-situ thermal recycling technology and employing a specific composition of activator, the interfacial energy between the asphalt and aggregate phases can be effectively reduced. This enhances the foaming effect of the foamed modified asphalt and promotes the foaming of the old asphalt on the surface of the RAP material, thereby increasing the activation rate of the old asphalt and reducing the amount of new asphalt required. The resulting in-situ foamed warm-mix asphalt mixture exhibits excellent road performance and service life. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the on-site thermal regeneration unit used in an application example of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0035] In this invention, unless specific techniques or conditions are specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Instruments and other equipment whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels. All raw materials used in this invention are readily available in the domestic market.

[0036] The design method for in-situ foam-temperature recycled mixtures is as follows:

[0037] The waste asphalt mixture (RAP material) retrieved from the old road site was extracted using a high-speed centrifuge to separate the aggregate and asphalt. The extracted aggregate was then screened to determine the gradation composition of the old aggregate.

[0038] Table 1. Results of RAP aggregate gradation extraction and screening.

[0039]

[0040] The amount of asphalt in RAP material was also determined through extraction tests. The tests showed that the asphalt-aggregate ratio in RAP material was 4.0%.

[0041] Aged asphalt in primary RAP material was recovered using the Absen distillation method as recycled asphalt, and its main performance indicators are shown in Table 2.

[0042] Table 2 Main performance indicators of recycled asphalt

[0043]

[0044]

[0045] Asphalt mixtures are structurally complex materials, and their road performance is closely related to their structural characteristics. Asphalt mixtures are a three-phase system composed of mineral aggregates, asphalt mastic, and air. The mineral aggregate skeleton is a discontinuous dispersed phase, and the asphalt mastic is the dispersion medium. The structure of an asphalt mixture refers to the characteristics of the interactions between its constituent materials, the distribution of their relative positions, and their interrelationships. Its structural characteristics are closely related to the material composition, the mechanical properties of the materials, and the relative positions of the components.

[0046] The structural composition of recycled asphalt mixtures is similar to that of ordinary asphalt mixtures, but the difference lies in the presence of RAP (Recycling Agent) and a recycling agent, ultimately forming a mixture of new asphalt, new aggregates, a recycling agent, and RAP. Both RAP and the recycling agent affect the strength development of the recycled mixture. Therefore, a reasonable mix design should be implemented during the recycling process, fully considering the material properties and mastering the construction technology to strive for high-performance recycled mixtures.

[0047] In the design of in-situ foamed warm recycled mixtures of this invention, the blending rate of RAP material should be determined first in order to determine the amount of asphalt activator, and then the amount of new asphalt added should be determined according to the Marshall method.

[0048] Based on the original road surface elevation and the comprehensive performance of the on-site foamed thermal recycled mixture, a RAP material blending rate of 70% by mass was selected for the recycling design. The blending rate = RAP material mass / (RAP material mass + new aggregate mass) * 100%.

[0049] The new aggregate includes new aggregates and mineral powder. The new aggregates are divided into four grades: 10-15mm, 5-10mm, 3-5mm, and 0-3mm. The 10-15mm and 5-10mm aggregates are basalt, while the 3-5mm and 0-3mm aggregates are limestone. The crushing value of the coarse aggregate is 14.3%, and the abrasion loss of the fine aggregate is 13.5%. The passing rates of each sieve aperture for both the new aggregates and mineral powder are shown in Table 3.

[0050] Table 3. Quality passing rate of fresh aggregate and mineral powder at various sieve openings

[0051]

[0052] The mix design of the new aggregate for in-situ foam-warm recycled mixture was carried out, and the design results are shown in Table 4.

[0053] Table 4. New aggregate mix proportions for in-situ foam-heated recycled aggregates

[0054]

[0055] The activator was incorporated into the recycled asphalt, and the recovery of indicators such as penetration was measured. After slow and thorough mixing, the mixture was poured into molds, and tests were conducted on softening point, penetration, ductility, viscosity, and visco-toughness. The test results are shown in Table 5 below. The activators incorporated included fatty acid alcohol amide, hexadecyltrimethylammonium bromide, and agar. The amount of fatty acid alcohol amide incorporated was 1.5% of the recycled asphalt, the amount of hexadecyltrimethylammonium bromide incorporated was 1%, and the amount of agar incorporated was 1%.

[0056] Table 5. Effect of activators on the performance of recycled asphalt

[0057]

[0058] Estimated amount of modified asphalt to be added to in-situ foamed warm recycled mixture

[0059] The design asphalt-aggregate ratio of in-situ foam-temperature recycled mixture can be initially estimated using the aforementioned empirical formula, and then adjusted according to the type of in-situ foam-temperature recycled mixture to preliminarily determine the design asphalt-aggregate ratio of in-situ foam-temperature recycled mixture.

[0060] ② Molded specimens

[0061] This oil-aggregate ratio was used as the median of the range for preparing Marviate specimens of in-situ foamed warm recycled mixture. The oil content was then divided into 5 grades by increasing and decreasing by 0.5%, with 5 specimens prepared for each grade.

[0062] ③ Determine the optimal amount of modified asphalt.

[0063] a. First, based on the new aggregate mix design, and combined with the tested aggregate density, new aggregate density, and modified asphalt density in the RAP mix, the theoretical maximum relative density of the in-situ foamed warm recycled mixture is obtained by calculation.

[0064] b. Test the bulk relative density of the in-situ foamed recycled mixture under various asphalt-aggregate ratios, and then calculate its void ratio, effective asphalt saturation, and aggregate void ratio respectively; test the stability and flow value of the Marshall specimen using a Marshall tester at the specified test temperature and test time.

[0065] c. Plot the relationship between modified asphalt dosage and physical and mechanical properties, with modified asphalt dosage as the abscissa and density, porosity, saturation, stability, and flowability as the ordinate. From each graph, select the modified asphalt dosage corresponding to the maximum stability, the maximum density, the median of the saturation range, and the target porosity. Use the average of these four modified asphalt dosages as the initial value OAC1 for the optimal modified asphalt dosage.

[0066] d. Take the median value of the modified asphalt dosage range OACmin to OACmax, where all indicators meet the technical standards (excluding VMA), as OAC2. Take the median value of OAC1 and OAC2 as the calculated optimal modified asphalt dosage OAC, and then check whether the VMA meets the minimum VMA requirement in the construction specifications.

[0067] The optimal modified asphalt content can be determined through the above-mentioned experimental methods combined with general engineering experience. As the RAP blending content increases, the optimal modified asphalt content also increases. This is mainly because the recycled asphalt in the RAP blend cannot fully integrate with the new asphalt, and the recycled asphalt in the RAP blend cannot fully play its role as a binder, resulting in the need to add relatively more new asphalt to the mixture to play its role as a binder.

[0068] Example 1

[0069] This embodiment provides an in-situ foamed warm recycled mixture, comprising 700 parts of RAP material, 300 parts of new aggregate, 16 parts of SBS modified bitumen, 0.48 parts of foaming water, and 0.56 parts of activator. The activator includes 0.24 parts of fatty acid alcohol amide, 0.16 parts of hexadecyltrimethylammonium bromide, and 0.16 parts of agar. The SBS modified bitumen is type ID SBS modified bitumen.

[0070] The preparation method of in-situ foamed warm recycled mixture is as follows: the modified asphalt is heated to a molten state, then an activator is added and stirred evenly, and the mixture is heated to the foaming temperature of the modified asphalt of 160°C. Then foaming water is added to foam the mixture to obtain foamed modified asphalt.

[0071] The obtained foamed modified asphalt was mixed with waste asphalt mixture and new aggregate at 150℃ for 60 seconds.

[0072] Example 2

[0073] This embodiment provides an in-situ foamed warm recycled mixture, which differs from Embodiment 1 in that it includes 900 parts of RAP material, 100 parts of new aggregate, 16 parts of SBS modified bitumen, 0.48 parts of foaming water, and an activator, which includes 0.24 parts of fatty acid alcohol amide, 0.16 parts of hexadecyltrimethylammonium bromide, and 0.16 parts of agar.

[0074] The preparation method of the in-situ foam-temperature recycled mixture is the same as in Example 1.

[0075] Example 3

[0076] This embodiment provides an in-situ foamed warm recycled mixture, which differs from Embodiment 1 in that it includes 500 parts of RAP material, 500 parts of new aggregate, 16 parts of SBS modified bitumen, 0.48 parts of foaming water, and an activator, which includes 0.24 parts of fatty acid alcohol amide, 0.16 parts of hexadecyltrimethylammonium bromide, and 0.16 parts of agar.

[0077] The preparation method of the in-situ foam-temperature recycled mixture is the same as in Example 1.

[0078] Example 4

[0079] This embodiment provides an in-situ foam-temperature regeneration mixture, which differs from Embodiment 1 in that the activator includes 0.16 parts of fatty acid alcohol amide, 0.08 parts of hexadecyltrimethylammonium bromide, and 0.08 parts of agar.

[0080] The preparation method of the in-situ foam-temperature recycled mixture is the same as in Example 1.

[0081] Example 5

[0082] This embodiment provides an in-situ foam-temperature regenerated mixture, which differs from Embodiment 1 in that the amount of activator used is 0.32 parts. The activator includes 0.14 parts of fatty acid alcohol amide, 0.09 parts of hexadecyltrimethylammonium bromide, and 0.09 parts of agar.

[0083] Comparative Example 1

[0084] This comparative example provides an in-situ foamed warm recycled asphalt mixture, which differs from Example 1 in that it does not contain an activator. Its preparation method is as follows: Modified asphalt is heated to its foaming temperature of 160°C, and then foaming water is added to foam the mixture, obtaining foamed modified asphalt. The obtained foamed modified asphalt is then mixed with waste asphalt mixture and new aggregate at 170°C for 60 seconds. During the experiment, construction was impossible without the addition of an activator; the temperature needed to be raised to 170°C for construction to proceed.

[0085] Comparative Example 2

[0086] This comparative example provides an in-situ foam warm recycling mixture, which differs from Example 1 in that the activator used is different. Specifically, the activator is 0.16 parts of silane + 0.16 parts of paraffin oil.

[0087] The asphalt-aggregate ratios of the in-situ foamed warm recycled mixtures in Examples 1-5 and Comparative Examples 1-2 are shown in Table 6. The test method for the asphalt-aggregate ratio refers to the Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering (JTG E20-2011)(T0722).

[0088] Table 6. Asphalt-aggregate ratio of in-situ foam-heated regenerated mixture

[0089]

[0090] Indoor performance evaluation of in-situ foam-heated recycled mixtures:

[0091] (1) High temperature stability is shown in Tables 7-8. The high temperature stability test method refers to the Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering (JTG E20-2011)(T0719) and the Design Specification for Asphalt Pavement of Highway (JTG D50-2017).

[0092] Table 7. Rutting test results of in-situ foamed warm recycled mixture

[0093] Dynamic stability (cycles / mm) Example 1 16579 Example 2 18236 Example 3 12432 Example 4 14773 Example 5 14325 Comparative Example 1 19091 Comparative Example 2 15662

[0094] Table 8 Results of Uniaxial Penetration Strength Test

[0095]

[0096]

[0097] As can be seen from the test results in Tables 7 and 8, the in-situ foam-temperature recycled mixture of the present invention has excellent high-temperature stability.

[0098] (2) Low temperature crack resistance is shown in Table 9. The crack resistance test method refers to the test procedure for asphalt and asphalt mixtures in highway engineering (JTG E20-2011)(T0728).

[0099] Table 9 Results of Low-Temperature Bending Tests on Beams of In-Situ Foam-Recycled Asphalt Mixture

[0100] Damage strain / με Example 1 3663.2 Example 2 2106.3 Example 3 3723.4 Example 4 3326.1 Example 5 3122.4 Comparative Example 1 3000.2 Comparative Example 2 3261.5

[0101] As can be seen from the test results in Table 9, when the RAP content in the in-situ foam warm recycling mixture of the present invention is below 70%, it exhibits excellent low-temperature crack resistance.

[0102] (3) Water stability is shown in Table 10. The water stability test method refers to the test procedure for asphalt and asphalt mixtures in highway engineering (JTG E20-2011)(T0729).

[0103] Table 10 Results of Water Stability Test for In-situ Foam-Warm Regenerated Mixture

[0104]

[0105]

[0106] As can be seen from the test results in Table 10, when the amount of RAP material in the in-situ foam warm recycling mixture of the present invention is less than 70%, it exhibits excellent water stability.

[0107] Based on the above test results, the in-situ foam-temperature recycled mixture of Example 1 of the present invention has the best performance indicators, with excellent high-temperature stability, low-temperature crack resistance and water stability, and high cost performance.

[0108] Experimental Example

[0109] To investigate the mixing ratio of SBS modified bitumen to foaming water, the following exploratory experiment was conducted:

[0110] Foaming experiments were conducted using ID-type SBS modified asphalt and different amounts of foaming water. The results are shown in Table 11 below.

[0111] Table 11 Results of SBS modified asphalt foaming test

[0112]

[0113] As shown in Table 11, the foaming temperature of SBS modified asphalt is 160℃, the optimal water content is 3.0%, the expansion rate is 6 times, and the half-life is >180s.

[0114] To investigate the optimal ratio of SBS modified asphalt to activator (1.5% fatty acid alcohol amide, 1.0% hexadecyltrimethylammonium bromide, and 1% agar), the following exploratory experiment was conducted:

[0115] The three raw materials of the activator were premixed in SBS modified asphalt heated to a fluid state and stirred evenly until foaming occurred. After the addition of the activator, the SBS modified asphalt produced smaller and denser bubbles, and the half-life increased significantly. The effect was improved. Foaming experiments were conducted using ID type SBS modified asphalt with different amounts of activator, and the results are shown in Table 12 below.

[0116] Table 12 Results of foaming test of SBS modified asphalt + activator

[0117]

[0118] Application examples

[0119] The in-situ foamed thermal recycling mixture of Embodiment 1 of this invention is applied to actual asphalt pavement. The in-situ recycling equipment used includes an in-situ thermal recycling unit. The in-situ thermal recycling unit consists of single machines with functions such as heating, loosening, and warming the old asphalt pavement, adding new materials, mixing and paving, and compaction. The width of a single lane is preferably 3.0 to 4.5 meters, and the construction speed is adjustable within the range of 2 m / min to 5 m / min. A schematic diagram of the in-situ thermal recycling unit is shown below. Figure 1 This invention adds an asphalt foaming device to the existing equipment used for adding new asphalt in the original in-situ thermal recycling process.

[0120] During the stages of adding, mixing, and paving new materials, asphalt foaming pipes are installed in the asphalt pipelines, ensuring that the asphalt mixed with the RAP material is foamed modified asphalt. Due to the use of foamed modified asphalt, the working temperature during the heating stage and the mixing and paving stages can be reduced by 15-20℃. The mixing time is increased by 10 seconds during the mixing stage, allowing the activator to fully react with the aged asphalt on the RAP material surface and improving the utilization rate of the aged asphalt.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An activator for in-situ foam-temperature regenerated mixtures, wherein the activator comprises 10-20 parts of fatty acid alcohol amide, 5-15 parts of hexadecyltrimethylammonium bromide and 5-15 parts of agar by weight.

2. The activator according to claim 1, characterized in that, The activator comprises, by weight, 15 parts fatty acid alcohol amide, 10 parts hexadecyltrimethylammonium bromide, and 10 parts agar.

3. An in-situ foam-warm recycled mixture, characterized in that, It includes waste asphalt mixture, new aggregate, modified asphalt, foaming water, and the activator as described in claim 1 or 2.

4. The in-situ foam-warm recycled mixture according to claim 3, characterized in that, The activator accounts for 2-3.5% of the amount of the modified asphalt.

5. The in-situ foam-warm recycled mixture according to claim 3, characterized in that, The modified asphalt is SBS modified asphalt; And / or, the amount of modified bitumen used is 5%-6% of the new aggregate; And / or, the foaming temperature of the modified asphalt is 150-170℃.

6. The in-situ foam-warm recycled mixture according to claim 5, characterized in that, The amount of modified asphalt used is 5.3% of the new aggregate.

7. The in-situ foam-warm recycled mixture according to any one of claims 3-6, characterized in that, The weight ratio of the waste asphalt mixture to the new aggregate is (6-8):(2-4).

8. The in-situ foam-warm recycled mixture according to claim 7, characterized in that, The weight ratio of the waste asphalt mixture to the new aggregate is 7:

3.

9. The in-situ foam-warm recycled mixture according to any one of claims 3-6, characterized in that, The amount of foaming water used is 2%-4% of the amount of modified asphalt used.

10. The method for preparing the in-situ foam-warm recycled mixture according to any one of claims 3-9, characterized in that, Includes the following steps: The modified asphalt is heated to a molten state, then an activator is added and stirred evenly. The mixture is then heated to the foaming temperature of the modified asphalt, and foaming water is added to foam the asphalt to obtain foamed modified asphalt. The obtained foamed modified asphalt is mixed with waste asphalt mixture and new aggregate.

11. The preparation method according to claim 10, characterized in that, The mixing temperature is 140-150℃ and the mixing time is 60-80s.

12. The preparation method according to claim 10 or 11, characterized in that, The preparation method is implemented using an in-situ recycling device; an asphalt foaming pipe is installed in the asphalt pipeline of the in-situ recycling device, and the foaming water is added to the molten mixture of modified asphalt and activator through the asphalt foaming pipe.

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