CN117007782A - New and old asphalt fusion degree evaluation method for heat-regenerated asphalt mixture - Google Patents
New and old asphalt fusion degree evaluation method for heat-regenerated asphalt mixture Download PDFInfo
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- 239000010426 asphalt Substances 0.000 title claims abstract description 401
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- 230000004927 fusion Effects 0.000 title claims abstract description 116
- 238000011156 evaluation Methods 0.000 title description 10
- 239000011800 void material Substances 0.000 claims abstract description 72
- 239000000463 material Substances 0.000 claims abstract description 48
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- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
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- 238000003801 milling Methods 0.000 description 2
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- 239000003208 petroleum Substances 0.000 description 2
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- 238000002791 soaking Methods 0.000 description 2
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- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 1
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Abstract
The application provides a method for evaluating the fusion degree of new asphalt and old asphalt of a heat-recycled asphalt mixture, which comprises the following steps: s1, obtaining old materials, and separating the old materials to obtain old asphalt and old aggregate; s2, obtaining new materials, wherein the new materials comprise new asphalt and new aggregate; s3, preparing an asphalt mixture based on the old asphalt, the old aggregate and the new material, dividing the asphalt mixture into a plurality of fusion groups according to the content of the old asphalt, and respectively detecting the void ratio of each fusion group; s4, calibrating the void ratio based on a plurality of groups of asphalt mixtures to obtain a void ratio-effective asphalt content relation curve; s5, obtaining a thermal regeneration asphalt mixture to be evaluated, testing the void ratio of the thermal regeneration asphalt mixture, and calculating the effective asphalt content of the thermal regeneration asphalt mixture based on the void ratio-effective asphalt content relation curve so as to calculate the new asphalt fusion degree and the old asphalt fusion degree of the thermal regeneration asphalt mixture.
Description
Technical Field
The application belongs to the technical field of recycling of highway asphalt mixtures, and particularly relates to a method for evaluating the fusion degree of new asphalt and old asphalt of a heat-recycled asphalt mixture.
Background
Along with the research and experience accumulation of the highway regeneration technology in China, the application range of the waste asphalt mixture is continuously enlarged, the waste asphalt mixture is gradually transited from the regeneration base layer to the asphalt surface layer, and the blending proportion of the waste asphalt mixture is increased from 10% to 30% or more. Under the double rigidity constraint of environmental resources, the old materials are used as excellent substitute materials of natural aggregates and asphalt, and the utilization efficiency and the high-quality utilization level of the old materials are required to be further improved. In the current mix proportion design of reclaimed asphalt mixtures, the estimation of the amounts of regenerant and new asphalt is determined based on the assumption that all old asphalt in old asphalt is activated. However, researches show that due to the short mixing time, hard and brittle aging of the old asphalt, part of the old asphalt still remains on the surface of the old asphalt and is not really fused with the new asphalt, so that the design error of the mixing ratio is increased, and the best road performance of the regenerated asphalt mixture is not achieved. Therefore, it is necessary to accurately evaluate the fusion degree of the new asphalt and the old asphalt of the reclaimed materials through an effective detection means, so that the design and the application of the reclaimed materials under the high blending rate of the old materials can be effectively guided.
At present, no unified evaluation standard for the fusion degree of new asphalt and old asphalt exists, but domestic and foreign scholars have tried a plurality of test means to study the problem, including methods of fluorescence microscope gray value, penetration index, infrared spectrum characteristic functional group content and the like. The fluorescence microscope gray value method has the advantages of expensive observation equipment, complex analysis method and high detection cost, and can only observe the local fusion degree of new asphalt and old asphalt; the penetration method needs to separate asphalt on the surface of magnetite aggregate by a large amount of chemical reagents, and has a large pollution problem; the infrared spectrum characteristic functional group content method can only observe the local fusion degree of new asphalt and old asphalt, and the test takes a long time. The prior art means only can detect the local fusion degree of new asphalt and old asphalt, has poor representativeness, large randomness and large detection error, and cannot be popularized and applied on a large scale due to the limitation of microscopic detection equipment and the influence of subjective factors.
Therefore, the evaluation method of the fusion degree of the new asphalt and the old asphalt of the hot recycled asphalt mixture needs to be optimized.
Disclosure of Invention
Based on the above-mentioned drawbacks and deficiencies of the prior art, it is an object of the present application to at least solve one or more of the above-mentioned problems of the prior art, in other words, to provide a method for evaluating the degree of fusion of old and new asphalt of a hot recycled asphalt mixture which meets one or more of the above-mentioned needs.
In order to achieve the aim of the application, the application adopts the following technical scheme:
the application provides a method for evaluating the fusion degree of new asphalt and old asphalt of a heat-recycled asphalt mixture, which comprises the following steps:
s1, obtaining old materials, and separating the old materials to obtain old asphalt and old aggregate;
s2, obtaining new materials, wherein the new materials comprise new asphalt and new aggregate;
s3, preparing an asphalt mixture based on the old asphalt, the old aggregate and the new material, dividing the asphalt mixture into a plurality of fusion groups according to the content of the old asphalt, and respectively detecting the void ratio of each fusion group;
s4, calibrating the void ratio based on a plurality of groups of asphalt mixtures to obtain a void ratio-effective asphalt content relation curve;
s5, obtaining a thermal regeneration asphalt mixture to be evaluated, testing the void ratio of the thermal regeneration asphalt mixture, and calculating the effective asphalt content of the thermal regeneration asphalt mixture based on the void ratio-effective asphalt content relation curve so as to calculate the new asphalt fusion degree and the old asphalt fusion degree of the thermal regeneration asphalt mixture.
According to the technical scheme, more old asphalt in the asphalt mixture is activated and migrates as the fusion degree of the old asphalt and the new asphalt is higher, and the activated old asphalt plays roles of lubricating and filling gaps similar to those of the new asphalt in the mixing and compacting process of the hot recycled asphalt mixture, so that the void ratio, namely the ratio between the volume of the gaps in the hot recycled asphalt mixture and the total volume of the gaps in the hot recycled asphalt mixture, can be used for evaluating the fusion degree of the old asphalt and the new asphalt of the hot recycled asphalt mixture.
And manufacturing a plurality of experimental groups by changing the addition amount of old asphalt to reduce randomness, detecting the void ratio of the plurality of experimental groups, obtaining a plurality of coordinate points based on the detected void ratio result and the effective asphalt content thereof, establishing a rectangular coordinate system by taking the effective asphalt content as a horizontal axis and the void ratio as a vertical axis, calibrating the plurality of coordinate points in the coordinate system, and smoothly connecting the plurality of coordinate points in the rectangular coordinate system to obtain a void ratio-effective asphalt content relation curve for mapping the relation between the effective asphalt content and the void ratio. It should be noted that the effective asphalt content in the present application refers to the asphalt content that is effectively usable in the asphalt mixture, and it is assumed that some of the asphalt is activated and transferred in the above-described experimental groups, so that the effective asphalt content in the above-described experimental groups refers to the sum of the partially activated old asphalt and the whole new asphalt.
When the relation curve of the void ratio and the effective asphalt content is applied, the void ratio of the sample to be evaluated is detected, the effective asphalt content of the sample to be evaluated is reversely calculated based on the relation curve of the void ratio and the effective asphalt content, and the fusion degree of the new asphalt and the old asphalt in the heat-regenerated asphalt mixture can be evaluated according to the calculation result of the effective asphalt content. The void ratio belongs to a laboratory conventional volume parameter index, the detection operation of the void ratio is simple and convenient, the technology is mature, the detection error is small, the efficiency is high, the detection cost is low, the evaluation method can realize the quantitative detection of the fusion degree of the whole new asphalt and old asphalt of the hot recycled asphalt mixture by means of the conventional volume parameter index, and accurate basic data is provided for the design of the hot recycled asphalt mixture, so that the design and the application of the hot recycled asphalt mixture are more accurate and reliable.
As a preferred embodiment, in step S3:
the fusion group includes a completely fused group having the old asphalt content of 100%, a completely unfused group having the old asphalt content of 0%, and a partially fused group excluding the old asphalt contents of the completely fused group and the completely unfused group.
As a preferred embodiment, the preparation of the asphalt mixture in step S3 includes the steps of:
selecting and mixing all the old asphalt with all the new asphalt, and then mixing all the new asphalt and the old asphalt which are mixed with all the old aggregate and the new aggregate to complete the preparation of the complete fusion group;
directly mixing all the new asphalt with all the old aggregate and the new aggregate to complete the preparation of the completely unfused group;
and selecting part of the old asphalt, mixing the old asphalt with all the new asphalt, and then mixing all the new asphalt, part of the old asphalt, all the old aggregate and the new aggregate which are mixed, so as to complete the preparation of the part of fusion group.
As a preferred embodiment, the preparation step of the partially fused set is performed a plurality of times, and the quality of the old asphalt selected each time is changed to obtain a plurality of the partially fused sets having different amounts of the old asphalt.
As a preferred embodiment, the detecting the void fraction of each fusion group in step S3 includes the steps of:
s31, acquiring the air quality of each fusion group in a dry statem a ；
S32, obtaining the water quality of each fusion group immersed for a first preset time periodm w ；
S33, obtaining the surface dry quality of wiping off the surface water after the fusion groups are immersed in the water for a first preset time periodm f ；
S34, each air quality based on each fusion groupm a Mass in the waterm w The quality of the surface drym f And calculating the corresponding void fraction.
As a preferable embodiment, the calculation formula of the void fraction in step S34 is:
wherein,S a the void fraction is indicated as such and is indicative of,m a representing the quality of the air-space,m w the quality of the water is represented by the water,m f indicating the quality of the tack-free.
As a preferred embodiment, each point on the void fraction-effective asphalt content curve in step S4 satisfies the following equation:
wherein, (x, y) is the coordinates of each point on the void ratio-effective asphalt content relation curve in a rectangular coordinate system.
As a preferable scheme, the calculation formula of the new asphalt and old asphalt fusion degree of the hot recycled asphalt mixture in step S5 is as follows:
wherein,DoBthe fusion degree of the new asphalt and the old asphalt is expressed,AC 0% blending represents the asphalt content blended under the assumption that the old asphalt is not completely blended with the new asphalt,EAC partial blending the effective asphalt content which can actually exert the effect in the thermal regeneration asphalt mixture obtained by calculation according to the calibration relation curve is shown,AC 100% blending represents the asphalt content blended assuming a complete fusion design of old and new asphalt.
Compared with the prior art, the application has the following beneficial effects:
the void ratio belongs to a laboratory conventional volume parameter index, the detection operation of the void ratio is simple and convenient, the technology is mature, the detection error is small, the efficiency is high, the detection cost is low, the evaluation method can realize the quantitative detection of the fusion degree of the whole new asphalt and old asphalt of the hot recycled asphalt mixture by means of the conventional volume parameter index, and accurate basic data is provided for the design of the hot recycled asphalt mixture, so that the design and the application of the hot recycled asphalt mixture are more accurate and reliable.
Further or more detailed benefits will be described in connection with specific embodiments.
Drawings
In order to more clearly illustrate the embodiments of the application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for evaluating the fusion degree of new asphalt and old asphalt of a hot recycled asphalt mixture.
FIG. 2 is a schematic representation of the synthetic gradation curve of an asphalt mixture according to the first embodiment of the present application.
FIG. 3 is a graph showing the relationship between void fraction and effective asphalt content in the first embodiment of the present application.
Fig. 4 is a schematic diagram of the degree of fusion of old asphalt and new asphalt in three experimental groups of asphalt mixtures in the first verification experiment of the first embodiment of the present application.
Fig. 5 is a schematic diagram of the degree of fusion of old asphalt and new asphalt in three groups of asphalt mixture experiments in a verification experiment of the first embodiment of the application.
FIG. 6 is a graph showing the relationship between the void fraction and the effective asphalt content of the two-point fitting calibration in the first embodiment of the present application.
FIG. 7 is a graph showing the relationship between the void fraction and the effective asphalt content of the three-point fitting calibration in the first embodiment of the present application.
FIG. 8 is a graph showing the relationship between the void fraction and the effective asphalt content of the four-point fitting calibration in the first embodiment of the present application.
FIG. 9 is a graph showing the relationship between the void fraction and the effective asphalt content of a six-point fitting calibration in the first embodiment of the present application.
FIG. 10 shows the fitting accuracy R in the first embodiment of the present application 2 Schematic diagram of the relationship with the fitted point curve.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application.
In the following description, embodiments of the application are provided, and various embodiments may be substituted or combined, so that the application is intended to include all possible combinations of the same and/or different embodiments described. Thus, if one embodiment includes feature A, B, C and another embodiment includes feature B, D, then the present application should also be considered to include embodiments that include one or more of all other possible combinations including A, B, C, D, although such an embodiment may not be explicitly recited in the following.
The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements described without departing from the scope of the application. Various examples may omit, replace, or add various procedures or components as appropriate. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples.
In order to facilitate better understanding of the embodiments of the present application, a description of an application scenario thereof is provided before a detailed explanation of a specific embodiment of the present application.
Embodiment one:
as shown in fig. 1, the embodiment provides a method for evaluating the fusion degree of new asphalt and old asphalt of a heat-recycled asphalt mixture, which comprises the following steps:
s1, obtaining old materials, and separating the old materials to obtain old asphalt and old aggregate.
More specifically, the asphalt in the recycled old material is separated by adopting an extraction and recovery technology to obtain old asphalt and old aggregate, so that the sustainability and economy of the asphalt material are improved. The old materials can also be obtained by milling the damaged road surface, so that the utilization rate of resources is improved, the generation of waste materials is reduced, and the resource consumption and the environmental impact are reduced.
S2, obtaining new materials, wherein the new materials comprise new asphalt and new aggregates.
More specifically, the new asphalt in this example is 90# road petroleum asphalt.
S3, preparing an asphalt mixture based on the old asphalt, the old aggregate and the new material, dividing the asphalt mixture into a plurality of fusion groups according to the content of the old asphalt, and respectively detecting the void ratio of each fusion group.
Specifically, the present example provides a preferred embodiment in step S3, wherein the fusion group includes a completely fused group having the old asphalt content of 100%, a completely unfused group having the old asphalt content of 0%, and a partially fused group excluding the old asphalt contents of the completely fused group and the completely unfused group.
Specifically, this example provides a preferred embodiment in step S3, and the preparation of the asphalt mixture includes the following steps:
selecting and mixing all the old asphalt with all the new asphalt, and then mixing all the new asphalt and the old asphalt which are mixed with all the old aggregate and the new aggregate to complete the preparation of the complete fusion group;
directly mixing all the new asphalt with all the old aggregate and the new aggregate to complete the preparation of the completely unfused group;
and selecting part of the old asphalt, mixing the old asphalt with all the new asphalt, and then mixing all the new asphalt, part of the old asphalt, all the old aggregate and the new aggregate which are mixed, so as to complete the preparation of the part of fusion group.
Specifically, this example provides a preferred embodiment in which the preparation steps of the partially fused set are performed a plurality of times, and the quality of the old asphalt selected each time is changed to obtain a plurality of partially fused sets having different amounts of the old asphalt.
Specifically, in a preferred embodiment provided in this embodiment, the detecting the void fraction of each fusion group in step S3 includes the following steps:
s31, acquiring the air quality m of each fusion group in a dry state a ；
S32, obtaining the water mass m of each fusion group immersed for a first preset time period w ；
S33, obtaining water outlet of each fusion group after soaking for a first preset time period, and wiping off surface waterQuality of surface dryness m f ；
S34, each air quality m based on each fusion group a Mass m in the water w The surface dry mass m f And calculating the corresponding void fraction.
More specifically, in this embodiment, the setting range of the first preset duration is [3min,5min ], preferably 3min, 4min, 5min.
Specifically, in a preferred embodiment provided in this embodiment, the calculation formula of the void ratio in step S34 is:
wherein,S a the void fraction is indicated as such and is indicative of,m a representing the quality of the air-space,m w the quality of the water is represented by the water,m f indicating the quality of the tack-free.
S4, calibrating to obtain a void ratio-effective asphalt content relation curve based on the void ratios of a plurality of groups of asphalt mixtures.
Specifically, the present example provides a preferred embodiment, and in step S4, each point on the air void fraction-effective asphalt content relationship curve satisfies the following equation:
wherein, (x, y) is the coordinates of each point on the void ratio-effective asphalt content relation curve in a rectangular coordinate system.
S5, obtaining a thermal regeneration asphalt mixture to be evaluated, testing the void ratio of the thermal regeneration asphalt mixture, and calculating the effective asphalt content of the thermal regeneration asphalt mixture based on the void ratio-effective asphalt content relation curve so as to calculate the new asphalt fusion degree and the old asphalt fusion degree of the thermal regeneration asphalt mixture.
Specifically, the present example provides a preferred embodiment, and the calculation formula of the new asphalt and old asphalt fusion degree of the hot recycled asphalt mixture in step S5 is as follows:
wherein,DoB（Degree of Blending）the fusion degree of the new asphalt and the old asphalt is expressed,AC 0% blending represents the asphalt content blended under the assumption that the old asphalt is not completely blended with the new asphalt,EAC partial blending the effective asphalt content which can actually exert the effect in the thermal regeneration asphalt mixture obtained by calculation according to the calibration relation curve is shown,AC 100% blending represents the asphalt content blended assuming a complete fusion design of old and new asphalt.
More specifically, the partial fusion groups in this embodiment are two groups, that is, the fusion group includes a group 1 complete fusion group, a group 2 complete unfused group, a group 3 partial fusion group, and a group 4 partial fusion group, which specifically operate as follows:
step one, old material preparation:
old asphalt and old aggregate are obtained by milling and recycling the site damaged road surface, the mixing amount of the old aggregate is set to be 32%, namely, the proportion of the sum of the old aggregate and the old aggregate is set to be 32%, the content of the old asphalt is set to be 1.53%, namely, the proportion of the sum of the old asphalt and the old aggregate is set to be 1.53%, and the content of the old aggregate is set to be 30.47%, namely, the proportion of the sum of the old aggregate and the old aggregate is set to be 30.47%.
The proportion of the mixing amount of the old materials is controlled to balance the performance and quality of the reclaimed asphalt mixture. The higher mixing amount of the old materials can realize better resource recycling and environmental benefit, and simultaneously reduce the cost. However, too high an amount of the old material may adversely affect the properties of the mixture, such as low-temperature cracking, durability, etc. According to the current design level of the hot recycled asphalt mixture, the mixing amount of the old materials is controlled to be about 30 percent in a certain proportion, and the embodiment is set to be 32 percent to meet the actual technical requirements.
The results of the classification of the old aggregate according to the particle size are shown in Table 1.
Table 1:
。
step two, preparing new materials:
the 90# road petroleum asphalt was selected as the new asphalt, the blending amount of the new material was set to 68%, i.e., the ratio of the sum of the new material and the old material was 68%, the content of the new asphalt was set to 3.57%, i.e., the ratio of the sum of the new asphalt and the old material was 3.57%, and the content of the new aggregate was set to 64.43%, i.e., the ratio of the sum of the new aggregate and the old material was 64.43%, according to the results of the size screening of the old aggregate gradation in table 1.
The synthetic gradation of the asphalt mixture after the addition of the new aggregate is shown in table 2.
Table 2:
as can be seen from fig. 2, the synthetic gradation of the asphalt mixture after the new aggregate is within the upper and lower limits of the specification, and the content design of the old asphalt, the old aggregate, the new asphalt and the new aggregate in the embodiment meets the specification requirements.
And step three, preparing a fusion group:
preparing a complete fusion group of the group 1, namely mixing and melting all new asphalt and all old asphalt, and then mixing with all old aggregate and new aggregate, so that the effective asphalt content of the asphalt mixture in the group 2 is equal to 5.10% of the sum of the using amounts of the new asphalt and the old asphalt, and the fusion degree of the new asphalt and the old asphalt in the group 1 is 100%;
preparing a group 2 completely unfused group, and mixing all new asphalt with all old aggregate and new aggregate, so that the effective asphalt content of the asphalt mixture in the group 2 is 3.57% of the new asphalt, and the fusion degree of the new asphalt and the old asphalt in the group 2 is 0%;
preparing a group 3 partial fusion group, namely mixing and melting all new asphalt and 1.02% old asphalt, and then mixing with all old aggregate and new aggregate, so that the effective asphalt content of an asphalt mixture in the group 3 is 4.59%;
and preparing a group 4 part of fusion group, and mixing the new asphalt with 0.51% of old asphalt, and then mixing the new asphalt with all the old aggregate and the new aggregate in the fourth group, so that the effective asphalt content of the asphalt mixture in the group 4 is 4.08%.
And step four, void fraction detection:
the volume parameters of the group 1, the group 2, the group 3 and the group 4 are respectively tested by adopting a surface drying method, namely the air quality of each fusion group in a dry state is obtainedm a Acquiring the water quality of each fusion group immersed for a first preset time periodm w The surface dry quality of wiping off the surface water after the first preset time period of soaking the fusion groups is obtainedm f Each of the air masses based on each of the fusion groupsm a Mass in the waterm w The quality of the surface drym f Using the formulaAnd calculating the corresponding void fraction.
The parameter values for the four groups of asphalt mixtures are shown in table 3.
Table 3:
。
calibrating a relation curve of void ratio and effective asphalt content:
based on the parameter values of the four groups of asphalt mixtures in table 3, fitting is performed by using a polynomial, wherein the polynomial is specifically:
wherein,AV（Air Void）the void fraction is indicated as the void fraction,K 1 、K 2 andK 3 each representing a polynomial fit coefficient,EACindicating the effective asphalt content.
The relation curve of the void ratio and the effective asphalt content is shown in fig. 3, and each point on the relation curve of the void ratio and the effective asphalt content satisfies the following equation:
wherein, (x, y) is the coordinates of each point on the void ratio-effective asphalt content relation curve in a rectangular coordinate system.
To further verify the void fraction-effective asphalt content relationship of this example, this example was verified in terms of both mixing time and aging degree.
Verification experiment one:
mixing time is a key design factor which is acknowledged to obviously influence the fusion degree of new asphalt and old asphalt, and three groups of asphalt mixtures prepared by different mixing time are arranged in the embodiment so as to test the differentiation degree and the sensibility of the embodiment on different fusion degrees of new asphalt and old asphalt.
In the first verification experiment, mixing time of three verification groups is respectively 180s,360s and 540s, and experimental conditions of the three verification groups are the same except for the mixing time. And (3) mixing and preparing according to the time of 180s,360s and 540s to obtain three asphalt mixture verification groups, and respectively testing the volume parameters of the three asphalt mixture verification groups.
The volume parameters of the three asphalt mix validation sets in validation experiment one are shown in table 4.
Table 4:
in table 4, VMA represents the mineral aggregate gap rate of the asphalt mix validation set, and VFA represents the effective asphalt saturation of the asphalt mix validation set.
Void ratio-effective asphalt content curve equation based on this exampleThe volume parameters (Table 4) of the three asphalt mixture verification groups of the verification experiment were calculated to obtain the effective asphalt contents of the three asphalt mixture verification groups of the verification experiment, and the effective asphalt of the three asphalt mixture verification groups of the verification experiment was based on the effective asphalt contents of the three asphalt mixture verification groups of the verification experimentContent, conversion equation of the present embodiment->And calculating to obtain the new and old asphalt fusion degree of the three asphalt mixture verification groups in the verification experiment.
The degree of fusion of the old asphalt and the new asphalt in the three asphalt mixture verification groups in this verification experiment is shown in table 5 and fig. 4.
Table 5:
as can be seen from the test results of the first verification experiment table 5 and fig. 4, the method for evaluating the fusion degree of the new asphalt and the old asphalt of the hot recycled asphalt mixture in the embodiment has good differentiation degree and sensitivity to the fusion degree of the new asphalt and the old asphalt of the hot recycled asphalt mixture under different mixing time conditions, the evaluation result also accords with the actual rule, and meanwhile, the test method is simple and efficient and has good popularization and application potential.
And (3) verification experiment II:
the aging degree of the old materials is also a key design factor influencing the fusion degree of the new asphalt and the old asphalt, the second verification experiment adopts three old materials with different aging degrees to prepare three asphalt mixture verification groups, and the rest test conditions except the aging degree of the old materials in the three asphalt mixture verification groups are set to be the same.
The old asphalt and the old aggregate in the old material are separated and recycled through an extraction recycling technology in a verification experiment, and rheological property parameters of the old asphalt on the surface of the old material with three different ageing degrees are tested.
The rheological properties of the old asphalt on the surface of the old materials with three different ageing degrees are shown in Table 6.
Table 6:
the three asphalt mixture verification groups are prepared by adopting old asphalt on the surfaces of three old materials with different ageing degrees in table 6, and the volume parameters of the three asphalt mixture verification groups are respectively tested.
The volume parameters of the three asphalt mix validation sets in validation experiment two are shown in table 7.
Table 7:
in Table 7, VMA represents the mineral aggregate gap rate of the asphalt mix validation set and VFA represents the effective asphalt saturation of the asphalt mix validation set.
Void ratio-effective asphalt content curve equation based on this exampleThe volume parameters (table 7) of the three asphalt mixture verification groups in the verification experiment are calculated to obtain the effective asphalt contents of the three asphalt mixture verification groups in the verification experiment, and the conversion equation of the embodiment is based on the effective asphalt contents of the three asphalt mixture verification groups in the verification experiment>And calculating to obtain the new and old asphalt fusion degree of the three asphalt mixture verification groups in the verification experiment.
The degree of fusion of the old asphalt and the new asphalt in the three asphalt mixture verification groups in the verification experiment is shown in table 8 and fig. 5.
Table 8:
as can be seen from the test results of the verification experiment two, table 8 and fig. 5, as the aging degree of the blending materials increases, the measured fusion degree of the new asphalt and the old asphalt in the hot recycled asphalt mixture decreases, the evaluation result accords with the actual rule, and meanwhile, the fusion result of the new asphalt and the old asphalt among the groups has obvious discrimination degree, so that the reliability and the effectiveness of the fusion degree evaluation method of the new asphalt and the old asphalt of the hot recycled asphalt mixture in the embodiment are further verified.
According to the combination of the first verification experiment and the second verification experiment, under the adjustment level of different design factors, the new and old asphalt fusion degree evaluation method of the hot recycling asphalt mixture can effectively evaluate the new and old asphalt fusion degree of the hot recycling asphalt mixture, and has the advantages of higher sensitivity and differentiation, and wide application range.
It should be noted that, the number of the partial fusion groups in the fusion groups in this embodiment may be set to other values than the present embodiment, and the present embodiment preferably sets the partial fusion groups to two groups, that is, the fusion groups in this embodiment are four groups in total. In order to further verify the reliability and effectiveness of the fusion group arrangement in this embodiment, four groups of experiments are set in this embodiment, and the number of the partial fusion groups in the four groups of experiments is respectively 0, 1, 2 and 4, so that the number of the fusion groups in the four groups of experiments is respectively 2, 3, 4 and 6, that is, the fitting points of the four groups of experiments are gradually increased, and the void ratio-effective asphalt content relation curves of the four groups of experiments are respectively calibrated in this embodiment.
The void fraction-effective asphalt content relationship curves of the four groups of experiments are shown in fig. 6, 7, 8 and 9 respectively.
The fitting accuracy R is calculated according to the relation curve of the void ratio and the effective asphalt content of four groups of experiments 2 Fitting accuracy R 2 The relationship with the fitted point curve is shown in fig. 10.
As can be seen from fig. 10, as the adopted fitting calibration data increases, the fitting accuracy of the curve improves. Fitting accuracy R obtained by linear fitting of two data points 2 For 0.9871, fitting accuracy R obtained by fitting four data points 2 0.9922 can be reached, but as the fitting data is further increased, the fitting accuracy R 2 The inflection point elevation effect is not apparent. Meanwhile, the fitting precision and the calibration experimental quantity of the calibration curve are considered, and the embodiment preferably adopts four data points to fit the relation curve of the void ratio and the effective asphalt content.
It should be noted that, for simplicity of description, the foregoing method embodiments are all described as a series of acts, but it should be understood by those skilled in the art that the present application is not limited by the order of acts described, as some steps may be performed in other orders or concurrently in accordance with the present application. Further, those skilled in the art will also appreciate that the embodiments described in the specification are all preferred embodiments, and that the acts and modules referred to are not necessarily required for the present application.
In the foregoing embodiments, the descriptions of the embodiments are emphasized, and for parts of one embodiment that are not described in detail, reference may be made to related descriptions of other embodiments.
The foregoing is merely exemplary embodiments of the present disclosure and is not intended to limit the scope of the present disclosure. That is, equivalent changes and modifications are contemplated by the teachings of this disclosure, which fall within the scope of the present disclosure. Embodiments of the present disclosure will be readily apparent to those skilled in the art from consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a scope and spirit of the disclosure being indicated by the claims.
Claims (8)
1. The method for evaluating the fusion degree of the new asphalt and the old asphalt of the heat-recycled asphalt mixture is characterized by comprising the following steps of:
s1, obtaining old materials, and separating the old materials to obtain old asphalt and old aggregate;
s2, obtaining new materials, wherein the new materials comprise new asphalt and new aggregate;
s3, preparing an asphalt mixture based on the old asphalt, the old aggregate and the new material, dividing the asphalt mixture into a plurality of fusion groups according to the content of the old asphalt, and respectively detecting the void ratio of each fusion group;
s4, calibrating the void ratio based on a plurality of groups of asphalt mixtures to obtain a void ratio-effective asphalt content relation curve;
s5, obtaining a thermal regeneration asphalt mixture to be evaluated, testing the void ratio of the thermal regeneration asphalt mixture, and calculating the effective asphalt content of the thermal regeneration asphalt mixture based on the void ratio-effective asphalt content relation curve so as to calculate the new asphalt fusion degree and the old asphalt fusion degree of the thermal regeneration asphalt mixture.
2. The method for evaluating the degree of fusion of old asphalt and new asphalt of a heat-regenerated asphalt mixture according to claim 1, wherein in step S3:
the fusion group includes a completely fused group having the old asphalt content of 100%, a completely unfused group having the old asphalt content of 0%, and a partially fused group excluding the old asphalt contents of the completely fused group and the completely unfused group.
3. The method for evaluating the degree of fusion of old asphalt and new asphalt of a heat-regenerated asphalt mixture according to claim 2, wherein the step S3 of preparing the asphalt mixture comprises the steps of:
selecting and mixing all the old asphalt with all the new asphalt, and then mixing all the new asphalt and the old asphalt which are mixed with all the old aggregate and the new aggregate to complete the preparation of the complete fusion group;
directly mixing all the new asphalt with all the old aggregate and the new aggregate to complete the preparation of the completely unfused group;
and selecting part of the old asphalt, mixing the old asphalt with all the new asphalt, and then mixing all the new asphalt, part of the old asphalt, all the old aggregate and the new aggregate which are mixed, so as to complete the preparation of the part of fusion group.
4. The method for evaluating the fusion degree of new asphalt and old asphalt of the heat-regenerated asphalt mixture according to claim 3, which is characterized by comprising the following steps of:
and carrying out the preparation steps of the partial fusion groups for a plurality of times, and changing the quality of the old asphalt selected each time to obtain a plurality of partial fusion groups with different content of the old asphalt.
5. The method for evaluating the degree of fusion of old asphalt and new asphalt of a heat-recycled asphalt mixture according to claim 1, wherein the step S3 of detecting the void ratio of each fusion group comprises the steps of:
s31, acquiring the air quality of each fusion group in a dry statem a ；
S32, obtaining the water quality of each fusion group immersed for a first preset time periodm w ；
S33, obtaining the surface dry quality of wiping off the surface water after the fusion groups are immersed in the water for a first preset time periodm f ；
S34, each air quality based on each fusion groupm a Mass in the waterm w The surface dry mass m f And calculating the corresponding void fraction.
6. The method for evaluating the degree of fusion of old asphalt and new asphalt of a heat-recycled asphalt mixture according to claim 5, wherein the calculation formula of the void ratio in step S34 is:
wherein,S a the void fraction is indicated as such and is indicative of,m a representing the quality of the air-space,m w the quality of the water is represented by the water,m f indicating the quality of the tack-free.
7. The method for evaluating the degree of fusion of old asphalt and new asphalt of a heat-recycled asphalt mixture according to claim 1, wherein each point on the relation curve of void ratio and effective asphalt content in the step S4 satisfies the following equation:
wherein, (x, y) is the coordinates of each point on the void ratio-effective asphalt content relation curve in a rectangular coordinate system.
8. The method for evaluating the degree of fusion of old asphalt and new asphalt of a thermal reclaimed asphalt mixture according to claim 1, wherein the calculation formula of the degree of fusion of old asphalt and new asphalt of the thermal reclaimed asphalt mixture in the step S5 is as follows:
wherein,DoBthe fusion degree of the new asphalt and the old asphalt is expressed,AC 0% blending represents the asphalt content blended under the assumption that the old asphalt is not completely blended with the new asphalt,EAC partial blending the effective asphalt content which can actually exert the effect in the thermal regeneration asphalt mixture obtained by calculation according to the calibration relation curve is shown,AC 100% blending represents the asphalt content blended assuming a complete fusion design of old and new asphalt.
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