RAP effective asphalt content evaluation method considering aggregate influence

Abstract

The invention discloses an RAP effective asphalt content evaluation method considering aggregate influence, which comprises the following steps: firstly, by analyzing the particle size composition proportion of a single-particle-size RAP sample after hot mixing and extraction, calculating the RAP crushing degree to quantify the caking degree, and classifying aggregates; then calculating the volume of the asphalt adhered to the surface of the mineral aggregate per unit mass under an extreme assumption condition by combining the composition proportion of the RAP with each particle size and the mass of the asphalt adhered to the surface; and finally, calculating the effective asphalt content in the RAP by adopting a mineral aggregate surface volume method according to the RAP particle size composition and the content of various aggregates. The method can truly reflect the actual participation degree of the asphalt in the hot recycled asphalt mixture, and provides a scientific basis for reasonable mix proportion design and regeneration process optimization.

Description

Technical Field

[0001] This invention belongs to the field of asphalt mixture recycling technology in highway engineering, specifically involving an analysis and evaluation method for the influence of aggregate structure on the effective asphalt content that can participate in mixing in reclaimed asphalt pavement (RAP). Background Technology

[0002] The recycling and reuse of reclaimed asphalt pavement (RAP) is an important technological approach to achieving green and low-carbon road construction and resource recycling. Through the rational recycling of RAP, project costs can be effectively reduced, asphalt and aggregate consumption can be decreased, and the environmental burden of construction waste can be lessened. In recent years, with the advancement of sustainable transportation systems, the demand for the application of recycled asphalt mixtures has become increasingly urgent.

[0003] During the milling, crushing, and collection of RAP, the adhesion of the aged asphalt film on the aggregate surface easily leads to varying degrees of adhesion and agglomeration between particles, forming "agglomerates" with a certain structural strength. These agglomerates are often difficult to completely break up and uniformly disperse during subsequent hot mixing. Even small-diameter RAP particles may undergo secondary agglomeration under the friction between new aggregate and RAP particles. Because the aged asphalt inside the unbroken agglomerates cannot contact the new asphalt and new aggregate, a discontinuous interface between the old and new asphalt is created, resulting in uneven distribution of effective asphalt content in the mixture, significantly affecting the mixing effect and road performance of the recycled asphalt mixture.

[0004] Currently, most existing methods for determining effective asphalt content employ traditional extraction or combustion methods, which only yield the total asphalt content of the mixture and cannot distinguish the actual contribution of aggregate structure to the effective asphalt content. This makes it difficult to accurately reflect the actual impact of aggregate presence on the performance of recycled asphalt mixtures. International research focuses primarily on mix design optimization and macroscopic performance control of recycled asphalt mixtures, while domestic research mainly concentrates on the mechanism of action and performance recovery of recycling agents. However, both domestically and internationally, systematic analysis and quantitative evaluation methods for the characteristics of RAP aggregate structure and its impact on effective asphalt content remain relatively lacking.

[0005] In summary, the existing technology lacks an analytical and evaluation method that can comprehensively consider the characteristics of aggregate structure and the determination of effective asphalt content within it. This largely restricts the accurate evaluation of the performance of recycled asphalt mixtures and the optimization and improvement of the recycling process. Summary of the Invention

[0006] The purpose of this invention is to provide an analytical and evaluation method for the effective asphalt content in recycled asphalt mixtures considering the presence of agglomerates. By analyzing the structure of RAP agglomerates, calculating their fragmentation degree, and measuring the volume of surface-adhered asphalt, this method can distinguish between weakly and strongly bonded agglomerates, thereby quantitatively evaluating their impact on the effective asphalt content. This method can accurately reflect the actual degree of asphalt participation in hot recycled asphalt mixtures, providing a scientific basis for rational mix design and recycling process optimization.

[0007] The technical solution adopted to achieve the above-mentioned objectives of this invention is as follows: An evaluation method for the effective bitumen content of RAP considering the influence of aggregates includes the following steps: Step (1): After heating and drying the collected RAP material, it is separated into different single particle size groups by sieving to obtain representative samples of each particle size, i.e., single particle size samples; centrifuge and extract each single particle size sample to separate the asphalt and mineral in each single particle size sample to obtain the true particle size composition ratio. Step (2): Mix each single particle size sample with the new aggregate and heat-stir. After cooling and kneading, sieve. Subtract the mass of the new aggregate in the particle size of each particle size of the mixture to obtain the mass of RAP in the particle size after heat mixing, which is the RAP heat-stirred gradation. Then extract and sieve. Subtract the mass of the new aggregate in the particle size of each particle size of the mixture after sieving to obtain the mass of RAP in the particle size after extraction, which is the RAP extraction gradation. The breakage factor (FD) of hot-mixed samples was calculated by comparing the masses of individual particle size samples before and after hot mixing and pre-extraction. m and extraction fragmentation FD e and further limit FD e The total aggregate content in RAP, FD m The content of weakly cohesive agglomerates in RAP, (FD) e -FD m The content of strongly cohesive agglomerates in RAP is represented by ). Step (3): Centrifuge the extract in step (1), calculate the mass of aged asphalt for each single particle size sample, and further calculate the surface asphalt volume of mineral material per unit mass under the two extreme assumptions of the mineral powder completely filling the voids and completely forming a paste with the asphalt, and take the average value to obtain the surface asphalt volume of mineral material per single particle size. Step (4): Based on the composition ratio of each single particle size sample and its surface asphalt-adhered volume, the total asphalt-adhered volume V of RAP is obtained by weighting. t Then, the adhesive asphalt volume V of the strongly cohesive agglomerate component was further calculated. eBased on the uniform adhesion of fine aggregates to the surface of coarse aggregates in strongly coarse aggregate components, a multi-point adhesion model was established to calculate the volume of asphalt adhered to the surface of strongly coarse aggregates, V. m Based on the characteristics of aggregated structure, the asphalt content inside strongly bonded aggregate components is estimated. The effective asphalt content P is calculated using the following formula: , In the formula, M i The quality of aged asphalt at the interface within the strongly bonded agglomerate components; M t M represents the total mass of the adhesive bitumen in the RAP; e The quality of asphalt adhered to by strongly cohesive agglomerated components; M m ρ represents the mass of asphalt adhered to by strongly cohesive agglomerates under a multi-point adhesion model; ρ is the density of asphalt.

[0008] Compared with existing technologies, the evaluation method for effective asphalt content in RAP considering the influence of agglomerates provided by this invention can distinguish between weakly and strongly bonded agglomerates, and then quantitatively analyze their impact on effective asphalt content. This method can truly reflect the service performance of hot recycled asphalt mixtures, providing a scientific basis for rational mix design and recycling technology optimization. Based on the calculated effective asphalt content, the optimal asphalt-aggregate ratio is corrected, and road performance comparisons further confirm the effectiveness of the method. Attached Figure Description

[0009] Figure 1 Flowchart for RAP sieving of single particle size and extraction process; Figure 2 Flowchart of hot mixing and extraction of single-size RAP and new aggregates; Figure 3 The images show the morphology of the granules after hot mixing: (a) weakly cohesive granules, and (b) strongly cohesive granules. Figure 4 A diagram of a "multi-point adhesion model" for strongly agglomerated particles of fine aggregate adhering to coarse aggregate; Figure 5 This is a schematic diagram illustrating the structural characteristics and asphalt content calculation of the agglomerates after hot mixing and extraction. Detailed Implementation

[0010] To facilitate understanding by those skilled in the art, the present invention will be further described in conjunction with the accompanying drawings and embodiments.

[0011] Example 1: The particle size distribution of single-size RAP after hot mixing and extraction was analyzed. Based on this, the RAP breakage degree was calculated, the degree of RAP agglomeration was quantified, and the agglomerates were classified (corresponding to...). Figure 1 , Figure 2 and Figure 3 ).

[0012] Step A: RAP pretreatment and screening / grouping (e.g.) Figure 1 (As shown)

[0013] RAP material was collected from the stockpile, heated to 120°C and held at that temperature for 2 hours to remove moisture and the low-temperature hardening effect. After cooling, it was sieved into single particle size groups according to the sieve aperture size (e.g., sieved according to standard sizes such as 16 mm, 13.2 mm, etc.), and 1000g samples of each single particle size were collected.

[0014] Step B: Single-size RAP extraction and sieving (e.g.) Figure 1 (As shown)

[0015] According to the method specified in the "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011 T0722-1993), centrifugation tests were conducted on each single particle size RAP (...16 mm, 13.2 mm...) to separate the asphalt and aggregate in the sample. The aggregate in the extractor was collected and dried in an oven at 105℃ until constant weight. After cooling, sieve tests were conducted to obtain the actual particle size composition ratio of each single particle size.

[0016] Step C: Hot mixing and extraction test of the mixture (e.g.) Figure 2 (As shown)

[0017] RAP was heated at 120℃ for 2 hours, and new aggregate was heated at 160℃ for 4 hours. Then, RAP of various single particle sizes was mixed with new aggregate in different proportions and stirred at 165℃ for 180 seconds. During cooling, the mixture was kneaded to prevent secondary adhesion. After complete cooling, the mixture was sieved. The mass of RAP after hot mixing in that particle size was obtained by subtracting the mass of new aggregate in that particle size from the mass of the mixture at that particle size; this is the RAP hot-mix gradation. The cooled mixture was then extracted. The mass of RAP after extraction was obtained by subtracting the mass of new aggregate in that particle size from the mass of the mixture at that particle size; this is the RAP extraction gradation.

[0018] Step D: RAP breakage and particle classification (e.g.) Figure 3 (As shown)

[0019] After hot mixing and extraction, the portion of RAP smaller than its single-size particle size is stripped off. The proportion of this portion to the total mass is called the degree of breakage of the single-size RAP. The degree of breakage (FD) of each single-size RAP is... m ,%) and extraction fragmentation (FD) e ,%) are calculated according to formulas (1) and (2).

[0020]

[0021] In the formula, m a The initial mass of a single-size RAP particle, in g; m b The mass of the initial particle size after hot mixing is expressed in g; m.c The mass of the initial particle size after extraction is expressed in g.

[0022] The actual hot mixing process of RAP does not reach the state of complete crushing and separation. RAP particles that can be peeled off are called weakly cohesive particles, and RAP particles that do not peel off are defined as strongly cohesive particles. The calculation formulas for various types of particles are as shown in formula (3).

[0023]

[0024] Example 2: Based on the particle size composition ratio of each single-size RAP and the mass of surface-adhered asphalt, the volume of surface-adhered asphalt per unit mass of aggregate was calculated under extreme assumptions.

[0025] Step A: Centrifugation test after RAP extraction

[0026] The extracts of each single particle size in step B of Example 1 were placed in a centrifuge for centrifugation to remove trace amounts of mineral powder from the extracts. The centrifuge speed was 4000 r / min and the centrifugation time was not less than 30 min. The mass (M, g) of aged asphalt in RAP was calculated, as shown in Equation (4).

[0027]

[0028] In the formula, m1 is the mass of RAP before extraction, in g; m2 is the mass of the mineral material remaining in the extractor after RAP extraction, in g; m3 is the mass of mineral powder adsorbed on the filter paper, in g; and m4 is the mass of mineral powder remaining at the bottom of the centrifuge cup after centrifugation of the extract, in g.

[0029] Step B: Volume of asphalt adhering to the surface of the aggregate

[0030] (1) Based on the proportion of the actual components of single-size RAP and the mass of aged asphalt, the volume of asphalt adhering to the surface of single-size RAP is calculated using two extreme assumptions (1. mineral powder completely fills the voids as filler and the RAP surface is entirely adhered to asphalt; 2. mineral powder and asphalt completely form asphalt mortar and adhere to the surface of the aggregate). The calculation formula is shown in Equation (5).

[0031]

[0032] In the formula:

[0033]

[0034]

[0035] A ij The percentage of RAP with particle size i when the particle size of the constituent component is j, %; V sjLet m be the volume of asphalt (asphalt mortar) adhering to the surface of each kilogram of aggregate with particle size j. 3 ρ is the density of asphalt, taken as 1.04 g / cm³. 3 M i Let be the mass of asphalt adhering to the surface of each kilogram of mineral material with particle size i, expressed in kg.

[0036] (2) Both forms of mineral powder will appear in asphalt mixtures, and their interaction with asphalt is based on two assumptions. Therefore, the average value under the two assumptions is taken as the volume of asphalt adhering to the surface of a single-size mineral aggregate per unit mass (V, ×10). -6 m 3 See equation (6).

[0037]

[0038] In the formula, V s1 and V s2 The volume of asphalt adhering to the surface of each kilogram of single-size aggregate, respectively, under assumptions 1 and 2, in m. 3 .

[0039] Example 3: Based on the particle size distribution ratio of single-size RAP and the content of various aggregates, the effective asphalt content in RAP was calculated using the aggregate surface volume method (e.g., Figure 4 , Figure 5 (As shown).

[0040] Step A: RAP component adheres to asphalt volume (V) t )

[0041] The volume (V) of asphalt adhering to the surface of RAP components was calculated based on the actual composition ratio of single-size RAP and the volume of asphalt adhering to the aggregate surface. t , ×10 -6 m 3 The calculation formula is shown in equation (7).

[0042]

[0043] In the formula, P i The percentage of mineral material with particle size i after RAP extraction of a certain single particle size, %; V i The volume of bitumen adhering to the surface of each kilogram of mineral aggregate with particle size i, ×10 -6 m 3 .

[0044] Step B: Volume of asphalt adhered to by strongly cohesive agglomerate components (V) e )

[0045] If the mineral aggregate in a strongly cohesive agglomerate component is composed of mineral aggregate smaller than its initial particle size that has been completely separated after extraction, then the volume (V) of asphalt adhering to the surface of this component is... e , ×10 -6 m 3 The calculation process is shown in equations (8) to (10).

[0046]

[0047] In the formula, B i The proportion of strongly cohesive agglomerates with particle size i, %; I i The proportion of mineral material with particle size i in the initial RAP gradation, %; (FD) e -FD m ) i The content of strongly cohesive agglomerates in RAP with particle size i, %; T j The percentage of strongly cohesive particles of size j in RAP, %; H （i，j+1） V represents the proportion of RAP aggregates with particle size i and (j+1) order in the component; j The volume of bitumen adhering to the surface of each kilogram of mineral aggregate with particle size j, ×10 -6 m 3 .

[0048] Step C: Volume of asphalt adhering to the surface of strongly bonded agglomerates (V) m )

[0049] Assuming that the fine aggregate (≤1.18mm, hexahedral) in strongly coarse aggregates is uniformly adhered to the coarse aggregate components, a "multi-point adhesion model" is established to calculate the volume (V) of asphalt adhered to the surface of the strongly coarse aggregates. m , ×10 -6 m 3 () Figure 4 ).

[0050]

[0051] In the formula, V 球i The volume of asphalt on the surface of spherical aggregates with a particle size of i, representing the size of strongly cohesive agglomerates in RAP, ×10 -6 m 3 V ci The volume of asphalt adhering to the surface of coarse aggregate in a strongly cohesive agglomerate component of particle size i, ×10 -6 m 3 B i The proportion of strongly cohesive agglomerates with particle size i, %; V i The volume of bitumen adhering to the surface of each kilogram of mineral aggregate with particle size i, ×10 -6 m 3 V jThe volume of bitumen adhering to the surface of each kilogram of aggregate with a particle size of j (≥2.36 mm) is multiplied by 10. -6 m 3 ;c ij The composition consists of strongly cohesive agglomerates with a particle size of i, and the proportion of coarse aggregate with a particle size of j in its components.

[0052] Step D: Determining the effective bitumen content (P)

[0053] Based on the characteristics of agglomerated structure, the asphalt content inside strongly bonded agglomerates (i.e., the ineffective aged asphalt content) is estimated. The formula for calculating the effective asphalt content (P) in RAP is shown in equation (15). Figure 5 (As shown).

[0054]

[0055] In the formula, V t The volume of asphalt bonded to the RAP component, ×10 -6 m 3 V e For strongly cohesive agglomerated components, the asphalt has a volume, ×10 -6 m 3 V m The mass of asphalt adhered to by strongly bonded agglomerates (“multi-point adhesion model”), ×10 -6 m 3 .

[0056] Example 4: Application verification case (based on the calculation method of effective asphalt content in RAP, the optimal asphalt-aggregate ratio is corrected and the road performance is compared and verified).

[0057] Step A: Calculation of effective bitumen content in RAP

[0058] Selecting the same batch of RAP material (AC-16), taking a RAP content of 30% as an example, the content of various aggregates of single-size RAP was calculated according to formulas (1) to (3), as shown in Table 1. Combining the content of various aggregates, the mineral aggregate volume method was used, and the volume of adhesive asphalt of RAP component (V) was calculated using formulas (4) to (14). t ), Calculation of the volume of asphalt adhered to by strongly cohesive agglomerate components (V) e ) and the volume of asphalt adhered to the surface of strongly cohesive agglomerates (V m Finally, the effective asphalt content in RAP was calculated according to formula (15), and the calculation results of each parameter are shown in Table 2.

[0059] Table 1 Content of various aggregates of RAP with single particle size

[0060]

[0061] Table 2. Content of effective bitumen in RAP

[0062]

[0063] Step B: Marshall's optimal oil-stone ratio

[0064] The new asphalt was selected from the same type as RAP as the original asphalt. The Marshall test method specified in JTG F40-2004 "Technical Specification for Construction of Highway Asphalt Pavement" was adopted. The initial asphalt-aggregate ratios were set at 4.0%, 4.5%, 5.0%, 5.5%, and 6.0%, and the optimal asphalt-aggregate ratio was corrected by the effective asphalt content. The volumetric parameters of Marshall before and after correction (bulk density, porosity, VMA, VFA, stability, and flow value) were obtained. Based on the volumetric parameters, the optimal asphalt-aggregate ratios of Marshall before and after correction were calculated to be 4.74% and 4.84%, respectively.

[0065] Step C: Road performance of hot recycled asphalt mixture

[0066] Based on the optimal asphalt-aggregate ratio before and after the correction, hot recycled asphalt mixture specimens were prepared. High temperature stability (high temperature rutting test), low temperature crack resistance (low temperature beam three-point bending test), and water stability (immersion Marshall test and freeze-thaw splitting test) were studied in accordance with the specification JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The dynamic stability, maximum flexural strain, residual stability and freeze-thaw splitting strength of the hot recycled asphalt mixture before and after the correction were obtained, as shown in Table 3.

[0067] Table 3 Road Performance of AC-16 Hot Recycled Asphalt Mixture

[0068]

[0069] Step D: Comparative analysis of experimental results before and after correction

[0070] The test results show that after modifying the effective asphalt, the optimal Marshall asphalt-aggregate ratio increases, meaning the amount of new asphalt increases, leading to differences in performance between the hot recycled asphalt mixture before and after modification. Specifically, the dynamic stability of the modified mixture slightly decreases, but its maximum flexural tensile strain, residual stability, and freeze-thaw splitting strength are significantly improved. The results demonstrate that the modification method effectively improves the low-temperature crack resistance and water stability of the mixture, resulting in better overall road performance than the unmodified mixture, thus verifying the effectiveness of the method of this invention.

Claims

1. A method for evaluating the effective asphalt content of RAP considering the influence of aggregates, characterized in that... Includes the following steps: Step (1): After heating and drying the collected RAP material, it is separated into different single particle size groups by sieving to obtain representative samples of each particle size, i.e., single particle size samples. Centrifugation was performed on each single particle size sample to separate the asphalt and mineral aggregate in each single particle size sample and obtain the true particle size composition ratio. Step (2): Mix each single particle size sample with the new aggregate and heat-stir. After cooling and kneading, sieve. Subtract the mass of the new aggregate in the particle size of each particle size of the mixture to obtain the mass of RAP in the particle size after heat mixing, which is the RAP heat-stirred gradation. Then extract and sieve. Subtract the mass of the new aggregate in the particle size of each particle size of the mixture after sieving to obtain the mass of RAP in the particle size after extraction, which is the RAP extraction gradation. The breakage factor (FD) of hot-mixed samples was calculated by comparing the masses of individual particle size samples before and after hot mixing and pre-extraction. m and extraction fragmentation FD e and further limit FD e The total aggregate content in RAP, FD m The content of weakly cohesive agglomerates in RAP, (FD) e -FD m The content of strongly cohesive agglomerates in RAP is represented by ). Step (3): Centrifuge the extract in step (1), calculate the mass of aged asphalt for each single particle size sample, and further calculate the surface asphalt volume of mineral material per unit mass under the two extreme assumptions of the mineral powder completely filling the voids and completely forming a paste with the asphalt, and take the average value to obtain the surface asphalt volume of mineral material per single particle size. Step (4): Based on the composition ratio of each single particle size sample and its surface asphalt-adhered volume, the total asphalt-adhered volume V of RAP is obtained by weighting. t Then, the adhesive asphalt volume V of the strongly cohesive agglomerate component was further calculated. e Based on the principle that fine aggregates in strongly bonded aggregates are uniformly adhered to the surface of coarse aggregates, a multi-point adhesion model was established, and the volume of asphalt adhering to the surface of strongly bonded aggregates, V, was calculated. m Finally, based on the characteristics of the aggregated structure, the asphalt content inside the strongly bonded aggregate component, i.e., the effective asphalt content P, is estimated using the following formula: ， In the formula, M i The quality of aged asphalt at the interface within the strongly bonded aggregate components; M t M represents the total mass of the adhesive bitumen in the RAP; e The quality of asphalt adhered to by strongly cohesive agglomerated components; M m ρ represents the mass of asphalt adhered to by strongly cohesive agglomerates under a multi-point adhesion model; ρ is the density of asphalt.

2. The evaluation method for effective asphalt content of RAP considering the influence of aggregates according to claim 1, characterized in that: In step (1), the collected RAP material is heated to 120°C and kept at a constant temperature for 2 hours to remove moisture and low-temperature hardening effect; after cooling, it is sieved into single particle size groups according to different particle size standards, and samples of each single particle size are collected in portions of 1000g.

3. The evaluation method for effective asphalt content of RAP considering the influence of aggregates according to claim 1, characterized in that: In step (1), after centrifugation extraction and separation of each single particle size sample, the mineral material in the extractor is collected and placed in an oven at 105℃ to be dried to constant weight. After cooling, a sieve test is performed to obtain the true particle size composition ratio of each single particle size sample. At the same time, the mass of aged asphalt is calculated from the difference between the mass before extraction and the mass of the residue after extraction.

4. The evaluation method for effective asphalt content of RAP considering the influence of aggregates according to claim 1, characterized in that: The hot mixing step in step (2) is as follows: each single particle size sample is heated at 120℃ for 2 hours, and the new aggregate is heated at 160℃ for 4 hours. Then, each single particle size sample and the new aggregate are mixed in different proportions and mixed at 165℃ for 180 seconds. During cooling, the mixture is kneaded to avoid secondary adhesion.

5. The method for evaluating the effective asphalt content of RAP considering the influence of aggregates according to claim 1, characterized in that: In step (2), after hot mixing and extraction, the mineral material smaller than the particle size of each single-size sample is stripped off. The proportion of this part to the total mass is the breakage degree of the single-size RAP; the hot mixing breakage degree FD of each single-size sample m and extraction fragmentation FD e Calculate according to formulas (1) and (2): ， ， In the formula, m a m represents the initial mass of each single-size sample; b The mass of the residue of the initial particle size after hot mixing; m c This refers to the mass of the residue at the initial particle size after extraction.

6. The method for evaluating the effective asphalt content of RAP considering the influence of aggregates according to claim 1, characterized in that: In step (3), the extract is centrifuged in a centrifuge to remove trace amounts of mineral powder. The centrifuge speed is 4000 r / min and the centrifugation time is not less than 30 min. The formula for calculating the mass M of the aged asphalt is shown in formula (4): ， In the formula, m1 is the mass of RAP before extraction; m2 is the mass of the mineral material remaining in the extractor after RAP extraction; m3 is the mass of mineral powder adsorbed on the filter paper; and m4 is the mass of mineral powder remaining at the bottom of the centrifuge cup after centrifugation of the extract.

7. The evaluation method for effective asphalt content of RAP considering the influence of aggregates according to claim 1, characterized in that: In step (3), the volume of asphalt adhering to the surface of a unit mass of mineral material is V. s The calculation formula is shown in equation (5): ， In the formula: ， ， ， A ij V represents the proportion of RAP with particle size i when the particle size of the constituent component is j; sj ρ is the volume of asphalt or asphalt mortar adhering to the surface of each kilogram of aggregate with particle size j; ρ is the density of asphalt; M i Let i be the mass of asphalt adhering to the surface of each kilogram of mineral material with particle size i; Further calculations were performed on the volume of asphalt adhering to the surface of each kilogram of single-size aggregate under the two extreme assumptions: the mineral powder completely fills the voids and it completely forms a binder with the asphalt. s1 and V s2 The average of the two values ​​is taken as the volume V of asphalt adhering to the surface of a single-size mineral aggregate per unit mass, as shown in equation (6): 。 8. The evaluation method for effective asphalt content of RAP considering the influence of aggregates according to claim 1, characterized in that: In step (4), the total adhesive bitumen volume V of RAP t The calculation formula is shown in equation (7): ， In the formula, P i V represents the percentage of mineral material with particle size i extracted from a single particle size sample; i The volume of asphalt adhering to the surface of each kilogram of mineral material with particle size i.

9. The method for evaluating the effective asphalt content of RAP considering the influence of aggregates according to claim 1, characterized in that: In step (4), the mineral aggregate in the strongly cohesive agglomerate component consists of mineral aggregate smaller than the initial particle size that has been completely separated after extraction, and its adhering asphalt volume V e The calculation formulas are shown in equations (8) to (10): ， ， ， In the formula, B i I represents the proportion of strongly cohesive agglomerates with a particle size of i; i The proportion of mineral aggregate with particle size i in the initial gradation of RAP; (FD) e -FD m ) i The content of strongly cohesive agglomerates in RAP with particle size i; T j H represents the proportion of strongly cohesive particles of size j in RAP; （i，j+1） V represents the proportion of RAP aggregates with particle size i and (j+1) order in the component; j The volume of asphalt adhering to the surface of each kilogram of mineral material with particle size j.

10. The method for evaluating the effective asphalt content of RAP considering the influence of aggregates according to claim 1, characterized in that: In step (4), a "multi-point adhesion model" is established to calculate the volume V of asphalt adhered to the surface of strongly bonded agglomerates. m The calculation formula is as follows: ， ， ， In the formula, V 球i V represents the volume of asphalt on the surface of spherical aggregates with a particle size of i, representing the size of strongly cohesive agglomerates in RAP; ci B represents the volume of asphalt adhered to the surface of coarse aggregate in a strongly cohesive agglomerate component with particle size i; i V represents the proportion of strongly cohesive agglomerates with a particle size of i; j c is the volume of asphalt adhering to the surface of each kilogram of mineral aggregate with particle size j (j≥2.36mm); ij It is a strongly cohesive agglomerate with a particle size of i, and its composition contains a proportion of coarse aggregate with a particle size of j.

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