Preparation of low-carbon durable recycled asphalt concrete and performance evaluation method thereof

Abstract

The present application relates to the technical field of road engineering, in particular to a kind of low-carbon durable recycled asphalt concrete preparation and its performance evaluation method, comprising: aging asphalt / SBS polymer activity and its content detection and calculation;Low-carbon durable recycled asphalt design;Low-carbon durable recycled asphalt concrete preparation;Recycled asphalt concrete long-term performance evaluation.The present application innovatively proposes recycled technology based on aging asphalt performance regulation, breaks through the design limitation of traditional recycled asphalt concrete by constructing "material-structure-performance" multidimensional correlation model, and finally forms a complete technical system covering raw material evaluation, mix design, construction quality control and performance prediction, which provides theoretical support and technical support for realizing the high-value and large-scale application of RAP.

Description

Technical Field

[0001] This invention relates to the field of road engineering technology, specifically to a method for preparing low-carbon, durable recycled asphalt concrete and evaluating its performance. Background Technology

[0002] Even after long-term service and aging, asphalt pavement still has a strong regenerative capacity. The technical process of remixing RAP with appropriate proportions of new asphalt and new aggregates to prepare recycled asphalt concrete for paving new or maintained pavements is called asphalt pavement recycling technology.

[0003] First, existing technologies often add recycling agents based on experience and the content of aged asphalt in RAP, neglecting to quantify the activity and content of aged asphalt / SBS polymers in RAP. This makes it impossible to accurately customize recycling agents for a particular batch of RAP, resulting in poor recycling effects and affecting the long-term durability of recycled asphalt concrete.

[0004] Secondly, for aged SBS polymer-modified asphalt mixtures, the recycling agents proposed in current research can only restore the component balance of the matrix asphalt in the aged SBS modified asphalt, and cannot rebuild the cross-linked network structure of the aged and fractured SBS polymer. At the same time, existing technologies generally use hot-mix recycling technology to recover RAP, and the mixing and compaction temperature is usually as high as 180°C or above to ensure sufficient compaction effect, which will lead to secondary aging of the recycled asphalt.

[0005] Furthermore, "pseudo-particles" are a concern in recycled asphalt pavements. Pseudo-particles refer to incompletely dispersed aggregate clumps formed during the recycling process of old asphalt mixtures due to the binding effect of aged asphalt. These clumps appear to be independent particles, but are actually multiple fine aggregates bound together with aged asphalt, potentially affecting the performance of the recycled mixture. Moreover, since recycled asphalt mixtures contain both new and old aggregates, the design of gradation curves presents more complex challenges.

[0006] Furthermore, current research generally holds two viewpoints. One is that the new and old asphalt are in a 100% fusion state, meaning that the RAP aged asphalt is 100% integrated with the new asphalt and exhibits the same bonding properties. In this case, the amount of new asphalt added to the recycled mixture is the optimal asphalt dosage minus the total amount of aged asphalt contained in the RAP mixture, requiring no correction. The other is that the new and old asphalt are in a 0% fusion state, meaning that the RAP aged asphalt does not integrate with the new asphalt at all and does not exhibit the same bonding properties. In this case, the amount of new asphalt added to the recycled mixture is the optimal asphalt dosage. However, both of these assumptions are unreasonable. In reality, the new and old asphalt in the recycled mixture undergo partial diffusion fusion, meaning that the RAP aged asphalt can exert a certain degree of new asphalt efficacy. The amount of new asphalt added should be equal to the optimal asphalt dosage minus the total amount of aged asphalt that has undergone diffusion fusion in the RAP aged asphalt, requiring correction.

[0007] Furthermore, according to the "Technical Specification for Recycling Asphalt Pavement of Highways" (JTG / T 5521-2019), the construction temperature of plant-mixed hot recycled asphalt mixtures needs to be 5-10℃ higher than that of ordinary hot-mix asphalt mixtures to ensure the compaction quality of recycled pavements. However, excessively high construction temperatures and insufficient temperature control precision not only exacerbate fossil energy consumption and greenhouse gas emissions but may also lead to performance degradation of recycled asphalt concrete. Although the current "Technical Specification for Construction of Asphalt Pavement of Highways" (JTG F40-2004) proposes a construction temperature control method based on viscosity-temperature curves for base asphalt, it does not clearly define the standard for determining the optimal construction temperature for modified asphalt and recycled asphalt mixtures. It is worth noting that due to the complex colloidal structure of modified asphalt and recycled asphalt, high-temperature viscosity testing of these materials has significant limitations—the apparent viscosity measured by a Brookfield rotational viscometer at high temperatures may be distorted because asphalt exhibits non-Newtonian fluid characteristics under these conditions, resulting in viscosity indices that cannot accurately reflect actual workability during construction.

[0008] Finally, most existing evaluation methods neglect the study of the aging characteristics of the asphalt material itself. In fact, the performance of recycled asphalt concrete after the fusion of new and old asphalt during service has a significant impact on its long-term service performance. However, there are currently few methods to establish a correlation model between material aging and performance degradation from the perspective of asphalt, which directly leads to limitations in the prediction of the long-term service performance of recycled asphalt concrete. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention provides a method for preparing and evaluating the performance of low-carbon durable recycled asphalt concrete, forming a complete technical system covering raw material evaluation, mix design, construction quality control, and performance prediction, providing theoretical support and technical assurance for the high-value and large-scale application of RAP.

[0010] To achieve the above objectives, the present invention provides the following technical solution: a performance evaluation method for low-carbon durable recycled asphalt concrete, comprising the following steps:

[0011] (1) After obtaining asphalt samples from recycled asphalt concrete, asphalt films are prepared by pressing.

[0012] (2) Infrared spectroscopy was performed on the asphalt film, and its infrared spectral density at 950 cm⁻¹ was calculated based on the obtained infrared spectral data. -1 ~1050cm -1 The area of ​​the characteristic peak enclosed by the wavelength range is denoted as A ;

[0013] (3) Based on the area of ​​the characteristic peak formed A Evaluation indexes for calculating the long-term performance of recycled asphalt concrete n The calculation formula is as follows:

[0014]

[0015] In the formula, This is a long-term performance evaluation index for recycled asphalt concrete; the smaller the value, the better its long-term service performance.

[0016] Preferably, in step (1), the preparation method of recycled asphalt concrete is as follows: S1, using the aging index of RAP material to identify the content of pseudo-particles in it, in order to assess whether it meets the usage standards; S2, determining the content of aged asphalt and aged SBS polymer in RAP material; S3, determining the type of composite warm-mix recycling agent, and determining the mixing ratio of each component based on the content of aged asphalt and aged SBS polymer in RAP material; S4, determining the mix ratio of new aggregate and RAP material; S5, determining the optimal construction temperature of warm-mix recycled asphalt; S6, determining the optimal dosage of new asphalt; S7, determining the specific preparation of recycled asphalt concrete.

[0017] Preferably, in step S1, a near-infrared (NIR) imaging system is used to rapidly identify and screen the RAP material, and the 1650 cm⁻¹ value is calculated. -1 ~ 1700cm -1 The area of ​​the C=O characteristic peak in the wavelength range is used to calculate the aging index of recycled materials. CIA The calculation formula is as follows:

[0018] ;

[0019] In the formula: For RAP material at 1650cm -1 ~ 1700cm -1 Characteristic peak area in the wavelength range The original asphalt corresponding to the RAP material is at 1650cm. -1 ~ 1700cm -1 The characteristic peak area within the wavelength range;

[0020] in, CIA A value of 1 to 2 indicates that the content of fake particles is extremely low; CIA A score of 3 to 5 indicates the presence of some pseudo-particles; CIA A value >5 indicates the enrichment of pseudo-particles, which cannot be used to prepare recycled asphalt concrete.

[0021] Preferably, in step S2, the RAP material is subjected to infrared spectroscopy testing: the test wavenumber range is 400 cm⁻¹. -1 ~4000cm -1 Infrared spectra were acquired through 32 scans, and then analyzed using OMNIC software to calculate the values ​​at 1700 cm⁻¹. -1 carbonyl group at 1030 cm -1 986 cm⁻¹ of sulfoxide groups and aged SBS polymers at the site -1 The carbon-carbon double bond on the polybutadiene and 2700 cm -1 ~ 3000 cm -1 The characteristic peak area of ​​the reference peak at that location.

[0022] Preferably, the sulfoxide index is calculated based on the characteristic peak area. SI Carbonyl index CI and carbon-carbon double bond index PB The calculation formula is:

[0023] ;

[0024] ;

[0025] ;

[0026] In the formula, 1030cm -1 Area of ​​characteristic peak of sulfoxide group; 1700cm -1 Area of ​​the characteristic peak of carbonyl group; 968cm -1 Area of ​​the characteristic peak of carbon-carbon double bond; 2700cm -1 ~ 3000cm -1 The characteristic peak area of ​​the reference peak.

[0027] Preferably, based on the sulfoxide index SI and carbonyl index CI Establish a predictive model for aging asphalt index AIAnd the SBS polymer index prediction model for aging PBI ,as follows:

[0028] ;

[0029] In the formula, and The weighting factor is determined using standard asphalt samples in the laboratory; the aged asphalt index is... AI The lower the value, the lower the activity of the aged asphalt;

[0030] ;

[0031] In the formula, the aging SBS polymer index PBI The larger the value, the lower the activity of the aged SBS polymer.

[0032] Preferably, five or more groups of RAP materials with different aging degrees are selected, and a mathematical relationship prediction model is established between the infrared spectral absorption peak area and the actual aged asphalt content and aged SBS polymer content, as follows:

[0033] ;

[0034] ;

[0035] In the formula, , and The coefficients of the aging asphalt content prediction model; and yes Content prediction model coefficients; , , , and The result was obtained by fitting the data using the least squares method.

[0036] The carbonyl index of the unknown RAP material CI sulfoxide index SI and carbon-carbon double bond index PB By substituting these values ​​into the mathematical relationship prediction model, the contents of aged asphalt and aged SBS polymer can be calculated.

[0037] Preferably, in step S3, the method for determining the blending ratio of each component in the composite warm-mix regenerator is as follows: The softener, SBS crosslinking agent, viscosity reducer, interface enhancer, and anti-aging agent in the composite warm-mix regenerator are respectively denoted as... X i1 , X i2 , X i3 , Xi4 and X i5 , X i1 + X i2 + X i3 + X i4 + X i5 =100, where the dosage of softener and SBS crosslinking agent is calculated based on the actual aging index of aged asphalt and aged SBS polymer in the RAP material; then according to X i1 ~ X i5 The uniformity of dosing was designed to obtain several experimental groups; subsequently, key evaluation indicators were determined based on the efficacy of each component in the composite warm-mix regenerator, among which, X i1 Corresponding to the depth of penetration, X i2 Corresponding length, X i3 Corresponding viscosity, X i4 Corresponding tensile strength, X i5 Corresponding to the softening point, the five key evaluation indicators were then converted into their performance contribution. Y i1 , Y i2 , Y i3 , Y i4 and Y i5 The sum of all contributions can be considered as the overall performance score, i.e. Y i The calculation formula is as follows:

[0038] ( i =1,2,3……; j =1,2,3……)

[0039] ( i =1,2,3……)

[0040] Finally, based on the experimental data from several sets, performance testing was conducted to determine... Y j and Y ij, obtained through repeated iterations using a cubic regression model. Y and X The regression equation between i is used to calculate the overall performance score. YThe largest corresponding X i1, X i2, X i3, X i4 and X i5 is the optimal ratio for a composite warm-mix regenerator.

[0041] Preferably, the softener is any one of paraffin oil, naphthenic oil, aromatic oil, alkane oil, biodiesel, microbially decomposed oil, ester oil, coal tar, pine tar, and lubricating oil; the SBS crosslinking agent is any one of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, bisphenol A type epoxy resin, phenolic epoxy resin, butyl glycidyl ether, isophorone diisocyanate, naphthalene diisocyanate, polyurethane prepolymer, and epoxy polybutadiene resin; the viscosity reducer is APTL type viscosity reducer, Dow-Y type viscosity reducer, or Aspha... The following are the following ingredients: ltan-B lignite wax, EC-120 aliphatic hydrocarbons, Aspha-Min, Advera, and Messio; the following are the following interface enhancers: silane coupling agents, aluminate coupling agents, titanate coupling agents, nano-silica, nano-clay, carbon nanotubes, lignin, and rosin derivatives; the following are the following anti-aging agents: phenyl-α-naphthylamine, 2,6-di-tert-butyl-p-cresol, dilaurate thiodipropionate, 2-hydroxy-4-methoxybenzophenone, benzotriazole, tea polyphenols, and rutin.

[0042] Preferably, in step S4, the method for determining the mix proportions of the new aggregate and RAP material is as follows: determine the sieving results of each grade of the new aggregate and RAP material; construct the objective function for mix proportion optimization design; and solve to obtain the optimized mix proportion scheme of the new aggregate and RAP material.

[0043] Preferably, in step S5, the method for determining the optimal construction temperature of warm-mix recycled asphalt is as follows: The warm-mix recycled asphalt is made into cylindrical samples, and the samples are tested at different temperatures using a dynamic shear rheology tester with a rotating plate. Based on the sample test data, the viscosity at different temperatures is calculated using the following formula:

[0044]

[0045] In the formula, It's viscosity; It is the resistance during testing; It is the set angular velocity; and These are the sample's thickness and moment of inertia, respectively.

[0046] Preferably, a scatter plot of the viscosity of warm-mix recycled asphalt on a rotating plate is plotted at different test temperatures to obtain the corresponding viscosity-temperature curve equation. The optimal mixing and construction viscosity of the corresponding warm-mix recycled asphalt is calculated using the isoviscosity method.

[0047] Preferably, in step S5, the method for determining the optimal amount of new asphalt is as follows: Square fixed aggregate is added as tracer aggregate during the mixing of recycled asphalt concrete. After cooling, the tracer aggregate is removed, and the asphalt on its surface is scraped off and recorded as recycled asphalt. RAP material is extracted to produce RAP aged asphalt. Infrared spectroscopy tests are performed on the new asphalt, RAP aged asphalt, and recycled asphalt, detecting their values ​​at 1030 cm⁻¹. -1 1700cm -1 And 2700cm -1 ~ 3000 cm -1 The absorbance at that location.

[0048] Preferably, the OMNIC analysis software was used to calculate the concentrations of new asphalt, aged asphalt, and recycled asphalt at the sulfoxide functional group 1030 cm⁻¹. -1 Carbonyl functional group 1700cm -1 And aliphatic hydrocarbons 2700cm -1 ~ 3000cm -1 The peak area at the point is determined, and then the sulfoxide / carbonyl index of the new bitumen is calculated sequentially. / 2. Sulfoxide / carbonyl index of aged asphalt / 2. Sulfoxide / carbonyl index of recycled bitumen / The calculation formula is as follows:

[0049] ; ;

[0050] ; ;

[0051] ; ;

[0052] In the formula, , , These are new asphalt at 1030cm -1 1700cm -1 And 2700cm -1 ~ 3000cm -1 Peak area at; , , These are the aged asphalt at 1030cm. -1 1700cm -1 And 2700cm -1 ~ 3000cm -1 Peak area at; , , They are Asphalt at 1030cm -1 1700cm -1 And 2700cm -1 ~ 3000cm -1 Peak area at that location.

[0053] Preferably, the sulfoxide transfer efficiency of RAP-aged bitumen is calculated based on the sulfoxide and carbonyl indices. and carbonyl transfer efficiency The calculation formula is as follows:

[0054] ;

[0055] .

[0056] Preferably, based on sulfoxide transfer efficiency and carbonyl transfer efficiency The diffusion fusion degree (DOB) of new and old asphalt in recycled asphalt concrete is calculated using the following formula:

[0057] ;

[0058] In the formula, It is the ratio of RAP aged asphalt to the best asphalt in recycled asphalt concrete.

[0059] The optimal amount of new asphalt added to recycled asphalt concrete is calculated using the following formula:

[0060] .

[0061] Preferably, the optimal asphalt content in recycled concrete is determined by Marshall mix design, and the optimal asphalt content includes the content of new asphalt and recycled asphalt; the RAP aged asphalt content in RAP materials is determined by combustion method.

[0062] Preferably, in step S6, the specific preparation method of recycled asphalt concrete is as follows: RAP material is cold-mixed with composite warm-mix recycling agent, and after pretreatment, warm-mix recycled asphalt is obtained. It is then mixed with new aggregate and new asphalt to obtain recycled asphalt concrete.

[0063] This invention provides a method for preparing and evaluating the performance of low-carbon, durable recycled asphalt concrete, which has the following advantages compared with existing technologies:

[0064] This invention innovatively proposes a recycling technology based on the performance regulation of aged asphalt. By constructing a multi-dimensional correlation model of "material-structure-performance", it breaks through the design limitations of traditional recycled asphalt concrete and ultimately forms a complete technical system covering raw material evaluation, mix design, construction quality control and performance prediction, providing theoretical support and technical guarantee for the high-value and large-scale application of RAP.

[0065] Compared to traditional performance testing methods such as direct tensile testing, the method for evaluating the long-term performance of recycled asphalt concrete in this invention has significant advantages. Traditional methods require repeated loading of specimens under actual stress conditions until failure, resulting in long testing cycles, cumbersome operations, extremely high requirements for specimen preparation precision, and significant investment of manpower and resources. The performance evaluation method proposed in this invention is based on infrared spectroscopy technology, which can quickly and conveniently obtain performance data. Furthermore, it eliminates the need for complex mechanical loading equipment and a large number of specimens, enabling real-time, dynamic monitoring of material fatigue performance under non-destructive conditions. This provides an efficient, accurate, and economical testing method for evaluating the long-term performance of recycled asphalt mixtures. Attached Figure Description

[0066] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0067] Figure 1 Infrared spectral test images of various RAP materials of this invention;

[0068] Figure 2 This is the infrared spectrum test image of sample 1 of the present invention;

[0069] Figure 3 This is the infrared spectrum test image of sample 2 of the present invention;

[0070] Figure 4 This is the optimized design diagram of the synthesis gradation curve for this invention;

[0071] Figure 5 The viscosity test results for the original SBS asphalt and warm-mix recycled asphalt of this invention are shown in the figure. Detailed Implementation

[0072] The following embodiments are provided to illustrate the implementation of this application in detail, so that the process of how this application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0073] Example 1

[0074] A performance evaluation method for low-carbon durable recycled asphalt concrete includes the following steps:

[0075] (1) After obtaining asphalt samples from recycled asphalt concrete, asphalt films with a diameter of about 3 mm are prepared by pressing.

[0076] (2) Infrared spectroscopy of the asphalt film was performed using an ATR module with a resolution of 4.0 cm⁻¹. -1 The sample scan count was 32, the background scan count was 16, the scan speed was 7.5 kHz, and the wavenumber range was 4000 cm⁻¹. -1 ~ 400cm -1 Based on the obtained infrared spectral data, its value at 950 cm⁻¹ was calculated. -1 ~ 1050cm -1 The area of ​​the characteristic peak enclosed by the wavelength range is denoted as A ;

[0077] (3) Based on the area of ​​the characteristic peak formed A Evaluation indexes for calculating the long-term performance of recycled asphalt concrete n' The calculation formula is as follows:

[0078]

[0079] In the formula, This is a long-term performance evaluation index for recycled asphalt concrete; the smaller the value, the better its long-term service performance.

[0080] Example 2

[0081] After obtaining core samples from three different recycled asphalt pavements (named pavement core samples 1, 2, and 3), asphalt samples from the pavement core samples were obtained by extraction. These samples were then tested according to the method described in Example 1. The test results were compared with those of the recycled asphalt concrete in Example 1. Details are shown in Table 1.

[0082] Table 1 Long-term performance evaluation results

[0083]

[0084] According to the long-term performance evaluation indicators of asphalt mixtures, The smaller the value, the better the fatigue resistance. The results show that the service performance from best to worst is: recycled asphalt concrete > pavement core sample 1 > pavement core sample 3 > pavement core sample 2.

[0085] In this embodiment, the specific preparation of recycled asphalt concrete is as follows: RAP material is cold-mixed with composite warm-mix recycling agent, pretreated at 140°C for 2 hours to obtain warm-mix recycled asphalt, and then mixed with new aggregate and new asphalt at 154°C for 75 seconds to obtain recycled asphalt concrete.

[0086] Taking 100kg of recycled concrete as an example, the RAP material is a highway surface layer milled material SBS modified RAP mixture (aged RAP asphalt content is 4.75%), with an addition amount of 40% and a mass of 40kg; the composite warm-mix recycling agent consists of aromatic oil as an aged matrix asphalt softener, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide as an SBS crosslinking agent, EC-120 as a viscosity reducer, nano-silica as an interface reinforcing agent, and 2,6-di-tert-butyl-p-cresol as an anti-aging agent, with addition amounts of aromatic oil of 40 × 4.75% × 48.6% × 27.5% (aged asphalt activity index) = 0.25kg; 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide as... 40 × 4.75% × 27.2% × 94% (Aging SBS Polymer Activity Index) = 0.49 kg; EC-120 is 40 × 4.75% × 10.1% = 0.19 kg; Nano-silica is 40 × 4.75% × 7.7% = 0.15 kg; 2,6-Di-tert-butyl-p-cresol is 40 × 4.75% × 6.4% = 0.12 kg; The new asphalt is the original SBS modified asphalt provided by a company in Hubei Province, and its addition amount is 100 × 6.1% - 40 × 4.75% × 66.89% (Fusion Degree) = 4.83 kg; The new aggregate is diabase, and its addition amount is 100 - 40 - 4.83 - 0.25 - 0.49 - 0.19 - 0.15 - 0.12 = 53.97 kg.

[0087] Example 3

[0088] A method for preparing low-carbon, durable recycled asphalt concrete is as follows:

[0089] S1. Use the aging index of RAP material to identify the content of false particles in it, so as to assess whether it meets the usage standards.

[0090] S2. Determine the content of aged bitumen and aged SBS polymer in the RAP material;

[0091] S3. Determine the type of composite warm mix recycler and determine the blending ratio of each component based on the aged asphalt content and aged SBS polymer content in the RAP material.

[0092] S4. Determine the mix proportions of the new aggregates and RAP materials;

[0093] S5. Determine the optimal construction temperature for warm-mix recycled asphalt;

[0094] S6. Determine the optimal amount of new asphalt;

[0095] S7. The RAP material is cold-mixed with the composite warm-mix recycling agent and pretreated at 140℃ for 2 hours to obtain warm-mix recycled asphalt. It is then mixed with new aggregate and new asphalt at 154℃ for 75 seconds to obtain recycled asphalt concrete.

[0096] ① Regarding step S1, determine the aging index of the RAP material and assess whether it can be used to prepare recycled asphalt concrete.

[0097] A near-infrared (NIR) imaging system is installed above the conveyor belt, with the detection device approximately 50cm away from the belt. The installation distance should ideally not exceed 80cm, otherwise NIR signal attenuation and a reduced signal-to-noise ratio will occur, leading to inaccurate results. The angle between the imaging device's camera and the conveyor belt should be 20°. During testing, the imaging system's camera should not be perpendicular to the conveyor belt to avoid light reflection from the aggregate surface, which could cause spectral distortion. The conveyor belt speed is set to 2m / s, and the spectral range collected is 1000cm². -1 ~ 4000cm -1 .

[0098] Two batches of samples were selected for testing. The RAP materials in both batches were rapidly identified and screened using a near-infrared (NIR) imaging system. The test results are as follows: Figure 2 and Figure 3 As shown, 1650cm was calculated using OMINC software. -1 ~ 1700cm -1 The area of ​​the C=O characteristic peak in the wavelength range is used to calculate the aging index of recycled materials. CIA The calculation formula is as follows:

[0099]

[0100] In the formula: For RAP material at 1650cm -1 ~ 1700cm -1 Characteristic peak area in the wavelength range The original asphalt corresponding to the RAP material is at 1650cm. -1 ~ 1700cm -1 The characteristic peak area within the wavelength range;

[0101] Due to the enrichment of aged asphalt, the aging index of pseudo-particles is high. CIA The presence of pseudo-particles in waste asphalt mixtures was determined by the following criteria, which were significantly higher than those of real recycled aggregates, as shown in Table 2.

[0102] Table 2 Criteria for Identifying Fake Particles in RAP Materials

[0103]

[0104] in,CIA A value of 1 to 2 indicates that the content of fake particles is extremely low; CIA A score of 3 to 5 indicates the presence of some pseudo-particles; CIA A value >5 indicates the enrichment of pseudo-particles, which cannot be used to prepare recycled asphalt concrete.

[0105] Table 3 Test Results of Samples

[0106]

[0107] ② Regarding step S2, determine the content of aged bitumen and aged SBS polymer in the RAP material.

[0108] Infrared spectroscopy was performed on the RAP material: the wavenumber range was 400 cm⁻¹. -1 ~ 4000cm -1 Infrared spectra were acquired through 32 scans, and then analyzed using OMNIC software to calculate the values ​​at 1700 cm⁻¹. -1 carbonyl group at 1030 cm -1 986 cm⁻¹ of sulfoxide groups and aged SBS polymers at the site -1 The carbon-carbon double bond on the polybutadiene and 2700 cm -1 ~ 3000 cm -1 The characteristic peak area of ​​the reference peak at that location.

[0109] Calculate the sulfoxide index based on the characteristic peak area. SI Carbonyl index CI and carbon-carbon double bond index PB The calculation formula is:

[0110] ;

[0111] ;

[0112] ;

[0113] In the formula, 1030cm -1 Area of ​​characteristic peak of sulfoxide group; 1700cm -1 Area of ​​the characteristic peak of carbonyl group; 968cm -1 Area of ​​the characteristic peak of carbon-carbon double bond; 1030cm -1 The characteristic peak area of ​​the reference peak.

[0114] According to the sulfoxide index SI and carbonyl index CI Establish a predictive model for aging asphalt index AIAnd the SBS polymer index prediction model for aging PBI ,as follows:

[0115] ;

[0116] In the formula, and The weighting coefficients, determined using standard asphalt samples in the laboratory, are 83.3% and 16.7%, respectively, representing the aging asphalt index. AI The lower the value, the lower the activity of the aged asphalt;

[0117] ;

[0118] In the formula, the aging SBS polymer index PBI A higher value indicates lower activity of the aged SBS polymer. The activity of aged asphalt can be classified by the aged asphalt / SBS polymer index, and thresholds for classifying the activity levels of aged asphalt and aged SBS polymer can be established.

[0119] Five or more groups of RAP materials with different aging degrees were selected, and a mathematical relationship prediction model was established between the infrared spectral absorption peak area and the actual aged asphalt content and aged SBS polymer content, as follows:

[0120] ;

[0121] ;

[0122] In the formula, , and The coefficients of the aging asphalt content prediction model; and yes Content prediction model coefficients; , , , and The result was obtained by fitting the data using the least squares method.

[0123] The carbonyl index of the unknown RAP material CI sulfoxide index SI and carbon-carbon double bond index PB By substituting these values ​​into the mathematical relationship prediction model, the contents of aged asphalt and aged SBS polymer can be calculated.

[0124] This embodiment selected seven RAP materials from different sources and under different service conditions. Infrared spectroscopy tests were conducted on these materials. Two were SBS-modified asphalt aged in standard and extended pressure aging chambers, two were SBS-modified RAP mixtures from highway mid-layer milling, and three were SBS-modified asphalt aged in ovens for different durations. Additionally, a sample of unprocessed SBS-modified asphalt provided by a company in Hubei Province was used as a control group. FTIR tests were conducted on the asphalt samples using both FTIR-DR and FTIR-ATR testing modules, with a wavenumber range covering 400 cm⁻¹. -1 ~ 4000cm -1 The number of scans was 32.

[0125] The obtained infrared spectrum is as follows Figure 1 As shown in Table 4; the calculated results of the characteristic peak area of ​​RAP material are shown in Table 5; the calculated results of the sulfoxide index, carbonyl index and carbon-carbon double bond index are shown in Table 6; the calculated results of the activity index of aged asphalt / aged SBS polymer are shown in Table 6.

[0126] Table 4 Calculation results of characteristic peak area of ​​RAP material

[0127]

[0128] Table 5. Calculation results of sulfoxide index, carbonyl index, and carbon-carbon double bond index

[0129]

[0130] Table 6. Calculation Results of Activity Index of Aged Asphalt / Aged SBS Polymer

[0131]

[0132] As shown in Table 6, the aging activity of the seven SBS modified asphalts, from smallest to largest, is as follows: 40h oven-heated aging asphalt, 60h oven-heated aging asphalt, 20h oven-heated aging asphalt, mid-layer milled RAP aging asphalt, RTFO+20h PAV aging asphalt, RTFO+40h PAV aging asphalt, and top-layer milled RAP aging asphalt. The SBS polymer content, from smallest to largest, is as follows: top-layer milled RAP aging asphalt, 60h oven-heated aging asphalt, mid-layer milled RAP aging asphalt, RTFO+40h PAV aging asphalt, 40h oven-heated aging asphalt, RTFO+20h PAV aging asphalt, and 20h oven-heated aging asphalt.

[0133] ③ Regarding step S3, determine the type of composite warm-mix recycling agent, and determine the blending ratio of each component based on the aged asphalt content and aged SBS polymer content in the RAP material.

[0134] Taking the top-layer milled RAP material in Table 6 as an example, for the required composite warm-mix regenerator, aromatic oil is selected as the softener for the aged matrix asphalt, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide as the SBS crosslinking agent, EC-120 as the viscosity reducer, nano-silica as the interface reinforcing agent, and 2,6-di-tert-butyl-p-cresol as the anti-aging agent. The softener, SBS crosslinking agent, viscosity reducer, interface reinforcing agent, and anti-aging agent are respectively denoted as... X i1 , X i2 , X i3 , X i4 and X i5 , X i1 + X i2 + X i3 + X i4 + X i5 =100, where the dosage of softener and SBS crosslinking agent is calculated based on the actual aging index of aged asphalt and aged SBS polymer in the RAP material; then according to X i1 ~ X i5 The doping uniformity design yielded several experimental groups, as shown in Table 7, which contains 12 experimental design schemes.

[0135] Table 7 Experimental Design Scheme

[0136]

[0137] Using RAP material as the target for performance restoration, 12 groups of composite warm-mix recycling agents shown in Table 7 were added to prepare warm-mix recycled asphalt under different recycling states. The penetration, ductility, viscosity, pull-out strength, and softening point of each group of warm-mix recycled asphalt were then tested. X i1 Corresponding to the depth of penetration, X i2 Corresponding length, X i3 Corresponding viscosity, X i4 Corresponding tensile strength, X i5 Corresponding softening points. As shown in Table 8.

[0138] Table 8 Results of Performance Recovery Tests for Warm-Mix Recycled Asphalt

[0139]

[0140] The five key evaluation indicators in Table 4 are converted into their performance contribution. Y i1 , Y i2 , Y i3 , Y i4 and Y i5 The sum of all contributions can be considered as the overall performance score, i.e. Y i The calculation formula is as follows:

[0141] ( i =1,2,3……; j =1,2,3……)

[0142] ( i =1,2,3……)

[0143] The calculation results are shown in Table 9.

[0144] Table 9 Test Results of Performance Contribution and Overall Performance Score

[0145]

[0146] Finally, based on the experimental data in Tables 8 and 9, performance tests were conducted to determine... Y j and Y ij By combining the cubic regression model and iterating repeatedly, we obtain... Y and X The regression equation between i is used to calculate the overall performance score. Y The largest corresponding X i1 , X i2 , X i3 , X i4 and X i5 This is the optimal ratio for the composite warm-stir regenerator. The final optimal formula is as follows: 48.6% aromatic oil, 27.2% 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide, 10.1% EC-120, 7.7% nano-silica, and 6.4% 2,6-di-tert-butyl-p-cresol.

[0147] ④ Regarding step S4, determine the mix ratio of new aggregate and RAP material (old aggregate).

[0148] First, the sieving results for each grade of new and old aggregates were determined. For new aggregates, a multi-point sampling method was used to reduce the sample size to obtain the required test mass. Specifically, the test mass was not less than 5 kg. The new aggregates were sieved using a vibrating sieve, and the sieving results for each grade were recorded. For old aggregates, samples needed to be taken from different locations in the RAP stockyard to avoid experimental randomness. Specifically, five subsamples were taken from different locations, each not less than 1 kg, and after mixing, sieving calculations were performed. The sieving results of the old aggregates are shown in Tables 10 and 11 below, and the passing rate of the target SMA-13 ​​synthetic gradation is shown in Table 12.

[0149] Table 10 Screening Results of Fresh Aggregates

[0150]

[0151] Table 11 Screening Results of Old Aggregates

[0152]

[0153] Table 12 Target Synthetic Grain Pass Rate

[0154]

[0155] Determine the screening results for each size range of the new and old aggregates; based on the screening results, divide the new aggregates into four sizes: 0~3mm, 3~6mm, 6~11mm, and 11~16mm. Record the admixture dosage of each size range of the new aggregates as follows: N 1. N 2. N 3. N 4; Divide the old aggregate into two grades, namely 0~8mm and 8~12mm old aggregate, and record the admixture dosage of each grade as follows: O 1 and O 2; Mineral powder content is recorded as K 1. Cement admixture is recorded as K 2; Record the results of the sieve aperture passing rates for each grade from 16mm, 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, to 0.075mm as follows: S 1. S 2. S 3…… S 10. The median sieve aperture passing rate is denoted as... M 1. M 2. M 3…… M 10; Record the throughput of new aggregates from 16mm to 0.075mm in the 0~3mm range. PN 11. PN 12.PN 13…… PN 110, the throughput of old aggregate at 10 different sizes, from 16mm to 0.075mm, is as follows: PO 11. PO 12. PO 13…… PO 110; Similarly, for the 3~6mm, 6~11mm, and 11~16mm sizes, the pass rates of the new aggregate from 16mm to 0.075mm for the ten sizes are respectively PN twenty one, PN twenty two, PN twenty three…… PN 210; PN 31. PN 32. PN 33…… PN 310; PN 41. PN 42. PN 43…… PN 410; The throughput of old aggregate at 10 different sizes, from 16mm to 0.075mm, is as follows: PO twenty one, PO twenty two, PO twenty three…… PO 210; PO 31. PO 32. PO 33…… PO 310; the throughput of mineral powder at 10 different sizes, from 16mm to 0.075mm, is as follows: PK 11. PK 12. PK 13…… PK 10; The pass rates for 10 cement thickness grades from 16mm to 0.075mm are respectively PK twenty one, PK twenty two, ​ twenty three…… ​ 20; Let the error value between the composite gradation and the median gradation for the 10 grades from 16mm to 0.075mm be [value missing]. R 1. R 2. R 3…… R 10. The total error of the mix design for optimizing the overall gradation curves of the new and old aggregates is RR; the final objective function for the mix design optimization is:

[0156]

[0157] in, ​ To optimize the total error of the mix design for new and old aggregates, ​ To optimize the total error of the mix design for new and old aggregates at each grade level,i The numbers 1 to 10 represent sieve aperture sizes of 16mm, 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, and 0.075mm, respectively. The error value between the specific grade's composite gradation and the median gradation is also shown. ​ The calculation formula is:

[0158]

[0159] in, ​ , ​ , ​ These represent the error value of the i-th grade, the pass rate of the composite gradation, and the pass rate of the median gradation, respectively. i The numbers 1 to 10 represent sieve aperture sizes of 16mm, 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, and 0.075mm, respectively.

[0160] Median gradation pass rate ​ Refer to the "Technical Specification for Construction of Asphalt Pavement on Highways" (JTG F40-2004). The formula for calculating the passing rate Ri of the synthetic gradation is determined by the gradation type and maximum particle size parameter: ;

[0161] in, ​ For the first i The pass rate of the composite gradation of the gear. N 1. N 2. N 3. N 4 represents the dosage of new asphalt at various grade levels. O 1. O 2 represents the dosage of different grades of old asphalt. K 1. K 2 represents the content of mineral powder and cement. X 1 represents the proportion of new aggregate in recycled asphalt concrete. X 2 represents the proportion of old aggregate in recycled asphalt concrete. ​ 1 i The first major category of new aggregates i The sieve aperture throughput of the filter. ​ 1 i The sieve aperture passing rate of the i-th sieve in the first major gradation of old aggregate. ​ 2 i , ​ 2 i , ​ 1 i The meanings are deduced by analogy. iThe numbers 1 to 10 represent sieve aperture sizes of 16mm, 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, and 0.075mm, respectively.

[0162] Based on the error solution function, the total error is... ​ The independent variable of the fitted objective function is N 1. N 2. N 3. N 4. O 1. O 2. K 1. K 2. Rewrite it in the following form:

[0163]

[0164] in, y To fit the objective function, X To fit the vector of independent variables to the objective function, i.e. X =[ N 1, N 2, N 3, N 4, O 1, O 2, K 1, K 2] T , β =[ β 0, β 1, β 2, β 3, β 4, β 5, β 6, β 7, β 8] T , is a parameter vector. ​ For the first i Error value of the file.

[0165] The objective function is fitted using the least squares method. Based on the L2 norm, the error function is as follows:

[0166]

[0167] in, Let be the error function. ​ For the first i The error value of the file, β =[ β 0, β 1, β 2, β 3,β 4, β 5, β 6, β 7,β8] T , is a parameter vector. ​ To fit the vector of independent variables to the objective function, i.e. ​ =[ N 1, N 2, N 3, N 4, O 1, O 2, K 1, K 2] T .

[0168] The optimal parameters are calculated using the solver in Excel, thus obtaining the best adsorption result. X O =[ N 1, N 2, N 3, N 4, O 1, O 2, K 1, K 2] T Complete the design optimization of the mix proportions of new and old aggregates.

[0169] For example, the synthetic gradation at a sieve size of 4.75 mm is:

[0170] S4= ( N 1*0.2+ N 2*0.9+ N 3*61.5+ N 4*100+ K 1*100+ K 2*100)+ X 2*( O 1*32.3+ O 2*84.6), the error value at this gear position R 4 = ( S 4-27) 2 .

[0171] assumed X 1 is 60%. X 2 was 40%, and the final results for different doping amounts were obtained, which are respectively N 1=33%, N 2=45%, N 3=2%, N 4=5%, O 1=15%, O2=85%, K 1 = 12% K 2=3%. The final composite gradation curve is shown below. ​ As shown.

[0172] ⑤ Regarding step S5, determine the optimal construction temperature for warm-mix recycled asphalt.

[0173] The viscosity of warm-mix recycled asphalt was measured using a dynamic shear rheology (DSR) rotating plate tester at temperatures ranging from 95 to 185°C. The warm-mix recycled asphalt consisted of 50% virgin SBS-modified asphalt and 50% RAP-aged asphalt. The sample diameter for the rotating plate test was 25 mm, and the thickness was 1 mm. The loading mode was stress-controlled, and the shear rate was 40 s⁻¹. -1 The temperature gradient was 10℃, and the termination condition for the rotating plate test was that the viscosity of the asphalt sample did not exceed 0.1 Pa·s.

[0174] Based on the raw data from the DSR rotating plate test, the formula was used. Calculate the viscosity of warm-mix recycled asphalt at different test temperatures; It's viscosity; It is the resistance during testing; It is the set angular velocity; and These are the sample's thickness and moment of inertia, respectively.

[0175] Spread scatter plots of the viscosity of warm-mix recycled asphalt on rotating plates at different test temperatures were plotted to obtain the corresponding viscosity-temperature curve equations. Using the isoviscosity method, and taking the conventional viscosity requirements for asphalt mixture mixing (0.17±0.02 Pa·s) and compaction (0.28±0.02 Pa·s) processes recommended in the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40-2004) as a reference, the optimal mixing and construction viscosity of the corresponding warm-mix recycled asphalt was calculated. ​ As shown in the figure, the mixing temperature of warm-mix recycled asphalt is 154℃, while the mixing temperature of the original SBS modified asphalt is 179℃, with the temperature reduction of warm-mix reaching 25℃.

[0176] ⑥ In step S6, determine the optimal amount of new asphalt.

[0177] Square fixed aggregates were added as tracer aggregates during the mixing of recycled asphalt concrete. After cooling, the tracer aggregates were removed, and the asphalt on their surface was scraped off and recorded as recycled asphalt. RAP aged asphalt was produced by extraction of RAP material. The optimal asphalt content in recycled asphalt concrete was determined to be 6.1% through Marshall mix design, including the content of new asphalt and recycled asphalt. The RAP aged asphalt content in RAP material was determined to be 4.75% through combustion method. The mix design of AC-13 recycled concrete was carried out with a composition of 40% RAP material and 60% new aggregate.

[0178] Infrared spectroscopy tests were conducted on new asphalt, RAP-aged asphalt, and recycled asphalt, with a wavenumber range of 400 cm⁻¹. -1 ~4000cm -1 The value was measured at 1030cm. -1 1700cm -1 And 2700cm -1 ~3000cm -1 Absorbance at that location;

[0179] The OMNIC analysis software was used to calculate the concentrations of the three asphalts at the sulfoxide functional group at 1030 cm⁻¹. -1 Carbonyl functional group 1700cm -1 And aliphatic hydrocarbons 2700cm -1 ~3000cm -1 The peak area at each point is denoted as A. 1030 A 1700 and A 2700~3000 Then, the sulfoxide / carbonyl index of the new bitumen is calculated sequentially. ; 2. Sulfoxide / carbonyl index of RAP aged bitumen ; and the sulfoxide / carbonyl index of recycled bitumen ; As shown in Table 13.

[0180] Table 13 Calculation results of FTIR peak area

[0181]

[0182] Calculation of sulfoxide transfer efficiency of RAP aged pitch based on sulfoxide and carbonyl indices and carbonyl transfer efficiency , , .

[0183] Assuming the preparation of 5 kg of recycled asphalt concrete (RAP) has an optimal asphalt content (total asphalt) of 6.1% and an optimal asphalt content of 0.3050 kg, the aged asphalt content in the RAP is 5 × 40% × 4.75% = 0.095 kg. What is the percentage of aged asphalt in the total asphalt content of the RAP? Therefore, the degree of fusion of recycled asphalt concrete is The results of the fusion degree calculation show that up to 66.89% of the aged asphalt in the RAP mixture has undergone fusion with the new asphalt. For 5 kg of recycled asphalt concrete, the actual optimal amount of new asphalt to add is... =0.02415kg, instead of the total asphalt content of 0.3050kg, which is obtained by directly subtracting the aged asphalt content of 0.095kg in RAP to get 0.21kg.

[0184] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A performance evaluation method for low-carbon durable recycled asphalt concrete, characterized in that, Includes the following steps: (1) After obtaining asphalt samples from recycled asphalt concrete, asphalt films are prepared by pressing. (2) Infrared spectroscopy was performed on the asphalt film, and its infrared spectral density at 950 cm⁻¹ was calculated based on the obtained infrared spectral data. -1 ~1050cm -1 The area of ​​the characteristic peak enclosed by the wavelength range is denoted as A ; (3) Based on the area of ​​the characteristic peak formed A Evaluation indexes for calculating the long-term performance of recycled asphalt concrete n' The calculation formula is as follows: ； In the formula, It is a long-term performance evaluation index for recycled asphalt concrete. The smaller the value, the better its long-term service performance. In step (1), the preparation method of recycled asphalt concrete is as follows: S1. Use the aging index of RAP material to identify the content of false particles in it, so as to assess whether it meets the usage standards. S2. Determine the content of aged bitumen and aged SBS polymer in the RAP material; S3. Determine the type of composite warm mix recycler and determine the blending ratio of each component based on the aged asphalt content and aged SBS polymer content in the RAP material. S4. Determine the mix proportions of the new aggregates and RAP materials; S5. Determine the optimal construction temperature for warm-mix recycled asphalt; S6. Determine the optimal amount of new asphalt; S7. Determine the specific preparation parameters for recycled asphalt concrete; In step S6, the method for determining the optimal amount of new asphalt is as follows: Square fixed aggregate is added as tracer aggregate during the mixing of recycled asphalt concrete. After cooling, the tracer aggregate is removed, and asphalt on its surface is scraped off and recorded as recycled asphalt. RAP material is extracted to produce RAP aged asphalt. Infrared spectroscopy tests are performed on the new asphalt, RAP aged asphalt, and recycled asphalt, detecting their values ​​at 1030 cm⁻¹. -1 1700cm -1 And 2700cm -1 ~ 3000 cm -1 Absorbance at that location; The OMNIC analysis software was used to calculate the concentrations of new asphalt, aged asphalt, and recycled asphalt at the sulfoxide functional group 1030 cm⁻¹. -1 Carbonyl functional group 1700cm -1 And aliphatic hydrocarbons 2700cm -1 ~ 3000cm -1 The peak area at the point is calculated, and then the sulfoxide index of the new bitumen is calculated sequentially. Carbonyl index sulfoxide index of aged asphalt Carbonyl index sulfoxide index of recycled bitumen Carbonyl index The calculation formula is as follows: ； ； ； ； ； ； In the formula, , , These are new asphalt at 1030cm -1 1700cm -1 And 2700cm -1 ~ 3000cm -1 Peak area at; , , These are the aged asphalt at 1030cm. -1 1700cm -1 And 2700cm -1 ~ 3000cm -1 Peak area at; , , They are Asphalt at 1030cm -1 1700cm -1 And 2700cm -1 ~ 3000cm -1 Peak area at; Calculation of sulfoxide transfer efficiency of RAP aged pitch based on sulfoxide and carbonyl indices and carbonyl transfer efficiency The calculation formula is as follows: ； ； Based on sulfoxide transfer efficiency and carbonyl transfer efficiency The diffusion fusion degree (DOB) of new and old asphalt in recycled asphalt concrete is calculated using the following formula: ； In the formula, It is the ratio of RAP aged asphalt to the best asphalt in recycled asphalt concrete. The optimal amount of virgin asphalt used in recycled asphalt concrete is calculated using the following formula: ； In the formula, This refers to the optimal amount of new asphalt used in recycled asphalt concrete. This refers to the total amount of asphalt in recycled asphalt concrete; This refers to the amount of aged asphalt on the RAP material in recycled asphalt concrete.

2. The performance evaluation method for low-carbon durable recycled asphalt concrete according to claim 1, characterized in that, In step (2), an ATR module was used for testing, with a resolution of 4.0 cm. -1 The sample scan count was 32, the background scan count was 16, the scan speed was 7.5 kHz, and the wavenumber range was 4000 cm⁻¹. -1 ~ 400cm -1 .

3. The performance evaluation method for low-carbon durable recycled asphalt concrete according to claim 1, characterized in that, In step S1, a near-infrared (NIR) imaging system is used to quickly identify and sieve the RAP material, and the 1650 cm⁻¹ value is calculated. -1 ~ 1700cm -1 The area of ​​the C=O characteristic peak in the wavelength range is used to determine the aging index of recycled materials. CIA The calculation formula is as follows: ； In the formula: For RAP material at 1650cm -1 ~ 1700cm -1 Characteristic peak area in the wavelength range The original asphalt corresponding to the RAP material is at 1650cm. -1 ~ 1700cm -1 The characteristic peak area within the wavelength range; in, CIA A value of 1 to 2 indicates that the content of fake particles is extremely low; CIA A score of 3 to 5 indicates the presence of some pseudo-particles; CIA A value >5 indicates the enrichment of pseudo-particles, which cannot be used to prepare recycled asphalt concrete.

4. The performance evaluation method for low-carbon durable recycled asphalt concrete according to claim 1, characterized in that, In step S2, infrared spectroscopy is performed on the RAP material: the wavenumber range is 400 cm⁻¹. -1 ~ 4000cm -1 Infrared spectra were acquired through 32 scans, and then analyzed using OMNIC software to calculate the values ​​at 1700 cm⁻¹. -1 carbonyl group at 1030 cm -1 986 cm⁻¹ of sulfoxide groups and aged SBS polymers at the site -1 The carbon-carbon double bond on the polybutadiene and 2700 cm -1 ~ 3000cm -1 The characteristic peak area of ​​the reference peak at that location.

5. The performance evaluation method for low-carbon durable recycled asphalt concrete according to claim 4, characterized in that, Calculate the sulfoxide index based on the characteristic peak area. SI Carbonyl index CI and carbon-carbon double bond index PB The calculation formula is: ； ； ； In the formula, 1030cm -1 Area of ​​the characteristic peak of the sulfoxide group; 1700cm -1 Area of ​​the characteristic peak of carbonyl group; 968cm -1 Area of ​​the characteristic peak of carbon-carbon double bond; 2700cm -1 ~ 3000cm -1 The characteristic peak area of ​​the reference peak.

6. The performance evaluation method for low-carbon durable recycled asphalt concrete according to claim 5, characterized in that, According to the sulfoxide index SI and carbonyl index CI Establish a predictive model for aging asphalt index AI And the SBS polymer index prediction model for aging PBI ,as follows: ； In the formula, and The weighting factor is determined using standard asphalt samples in the laboratory; the aged asphalt index is... AI The lower the value, the lower the activity of the aged asphalt; ； In the formula, the aging SBS polymer index PBI The larger the value, the lower the activity of the aged SBS polymer; It is the carbon-carbon double bond index of aged SBS modified bitumen; It is the carbon-carbon double bond index of the original SBS modified bitumen.

7. The performance evaluation method for low-carbon durable recycled asphalt concrete according to claim 5, characterized in that, Five or more groups of RAP materials with different aging degrees were selected, and a mathematical relationship prediction model was established between the infrared spectral absorption peak area and the actual aged asphalt content and aged SBS polymer content, as follows: ； ； In the formula, , and The coefficients of the aging asphalt content prediction model; and yes Content prediction model coefficients; , , , and The result was obtained by fitting the data using the least squares method. The carbonyl index of the unknown RAP material CI sulfoxide index SI and carbon-carbon double bond index PB By substituting these values ​​into the mathematical relationship prediction model, the contents of aged asphalt and aged SBS polymer can be calculated.

8. The performance evaluation method for low-carbon durable recycled asphalt concrete according to claim 1, characterized in that, In step S4, the method for determining the mix proportions of new aggregates and RAP materials is as follows: determine the sieving results of each grade of new aggregates and RAP materials; construct the objective function for mix proportion optimization design; and solve to obtain the optimized mix proportion scheme of new aggregates and RAP materials.

9. The performance evaluation method for low-carbon durable recycled asphalt concrete according to claim 1, characterized in that, In step S5, the method for determining the optimal construction temperature of warm-mix recycled asphalt is as follows: The warm-mix recycled asphalt is prepared into cylindrical samples, and the samples are tested at different temperatures using a dynamic shear rheology tester with a rotating plate. Based on the sample test data, the viscosity at different temperatures is calculated using the following formula: ； In the formula, It's viscosity; It is the resistance during testing; It is the set angular velocity; and These are the sample's thickness and moment of inertia, respectively.

10. The performance evaluation method for low-carbon durable recycled asphalt concrete according to claim 9, characterized in that, Plot the scatter plot of the viscosity of warm-mix recycled asphalt on a rotating plate at different test temperatures to obtain the corresponding viscosity-temperature curve equation. Use the isoviscosity method to calculate the optimal mixing and construction viscosity of the corresponding warm-mix recycled asphalt.

11. The performance evaluation method for low-carbon durable recycled asphalt concrete according to claim 1, characterized in that, The optimal asphalt content in recycled concrete is determined by Marshall mix design, and the optimal asphalt content includes the amount of new asphalt and recycled asphalt; the RAP aged asphalt content in RAP materials is determined by combustion method.

12. The performance evaluation method for low-carbon durable recycled asphalt concrete according to claim 11, characterized in that, In step S7, the specific preparation method of recycled asphalt concrete is as follows: RAP material is cold-mixed with composite warm-mix recycling agent, and after pretreatment, warm-mix recycled asphalt is obtained. It is then mixed with new aggregate and new asphalt to obtain recycled asphalt concrete.

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