CN111739592B - Method for quantifying new-old asphalt interface fusion degree based on asphalt mixture performance - Google Patents
Method for quantifying new-old asphalt interface fusion degree based on asphalt mixture performance Download PDFInfo
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Abstract
The invention discloses a method for quantifying the degree of new-old asphalt interface fusion based on asphalt mixture performance, which comprises the following steps: RAP pretreatment is carried out, and the synthetic design grading and the optimal asphalt consumption are determined; screening conventional performance indexes capable of being used for quantitatively calculating the DOB of the new-old asphalt interface fusion degree, and determining the change relation of the performance indexes along with the asphalt consumption; determining the performance index test result P of the concrete sample in the 'black stone' state, the actual regeneration state and the 100% complete fusion state of a new-old asphalt interface 1 、P 2 、P 3 Effective asphalt content x 1 、x 2 、x 3 The method comprises the steps of carrying out a first treatment on the surface of the And calculating and obtaining the new-old asphalt interface fusion degree in the actual regeneration state according to the proportion relation of the effective asphalt contents in different states. The invention has the beneficial effects that: the DOB of the new-old asphalt interface fusion degree of the regenerated mixture can be obtained in a crude engineering field laboratory through a mix proportion design flow without high-end instrument equipment, so that the regeneration performance of the RAP can be judged in time by engineering field constructors.
Description
Technical Field
The invention relates to the technical field of road engineering-asphalt pavement material regeneration application, in particular to a method for quantifying new-old asphalt interface fusion degree based on asphalt mixture performance.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
At present, the high-grade road asphalt pavement has entered a development stage and mode of construction-maintenance and progress. The asphalt pavement material performance is greatly deteriorated along with the fact that the service life of the established asphalt pavement is alternately close to that of the established asphalt pavement and under the comprehensive factors such as repeated driving load, warm and humid environment circulation and the like. The traditional method is that asphalt pavement materials RAP (Reclaimed Asphalt Pavement, RAP for short) with deteriorated performances are crushed, milled, recovered and abandoned, piled up and buried, but the residual polyaromatic hydrocarbon and soluble chemical components in the waste asphalt can cause ecological pollution and damage to air, soil and water sources. Therefore, development of large-doping, good quality and wide-range regeneration and recycling of the RAP recovered by milling has gradually become a hot technical field recommended by modern road construction departments and deeply researched by road engineering practitioners, and has become an important layout means and overall planning direction for sustainable development of road traffic construction engineering.
However, recycling RAP requires the addition of a certain amount of fresh asphalt or even regenerant. When new asphalt and a regenerant (when necessary to be added) act with old asphalt on the surface of RAP, certain degree of interaction fusion reaction (the fusion reaction degree is between 0 and 100%) can necessarily occur in the interface area, and the action state of the new-old asphalt interface regeneration fusion can directly influence the road mechanical performance of the regenerated asphalt mixture. However, the prior art cannot scientifically and definitely quantitatively characterize the new-old asphalt interface fusion degree DOB (Degree of Blending, abbreviated as DOB) in the regenerated mixture, and the uncertainty and even the unknown degree of the new-old asphalt interface fusion degree DOB can cause the actual regenerated asphalt pavement engineering to have great fluctuation of road performance and high probability and high risk of pavement diseases.
Disclosure of Invention
In view of the above, the invention provides a method for quantifying the degree of new-old asphalt interface fusion based on the performance of asphalt mixture, which only needs to utilize the mixing proportion of new asphalt mixture and reclaimed asphalt mixture to form a design flow and related conventional performance indexes, and can obtain the degree of new-old asphalt interface fusion DOB in reclaimed mixture without other performance tests, thus the operation is quick and simple, the method is scientific and clear, and the result is accurate and effective.
In order to achieve the above object, in some embodiments, the following technical solutions are adopted:
a method for quantifying the fusion degree of a new-old asphalt interface based on the performance of an asphalt mixture comprises the following steps:
preprocessing the waste asphalt pavement material RAP, and determining the synthetic design grading and the optimal asphalt consumption;
screening out performance indexes capable of being used for quantitatively calculating the fusion degree of a new asphalt interface and an old asphalt interface, and determining the change relation of the performance indexes along with the asphalt consumption;
substituting the performance index into a test result of the performance index of the recycled asphalt concrete sample in an actual recycling state based on the change relation of the performance index along with the asphalt consumption to obtain the content of the effective asphalt in the recycling state;
and combining the effective asphalt content of the new-old asphalt interface in a 0% fusion state and the effective asphalt content of the new-old asphalt interface in a 100% complete fusion state, and calculating the fusion degree of the new-old asphalt interface in an actual regeneration state through the proportional relation of the three.
Compared with the prior art, the invention has the beneficial effects that:
(1) The invention utilizes the mixing proportion of the new asphalt mixture and the regenerated asphalt mixture to form a design flow, and can obtain the DOB of the new-old asphalt interface fusion degree only through the conventional physical and mechanical performance indexes of the asphalt mixture without other performance tests, thereby having quick and simple operation. Therefore, the method has the most remarkable advantages that the DOB of the new-old asphalt interface fusion degree in the regenerated mixture can be obtained under the condition of a crude engineering site laboratory without high-end instruments and equipment, so that engineering site constructors can conveniently and timely judge the RAP regeneration performance, the construction quality of the regenerated asphalt pavement is effectively controlled, the method has good universal value, and the speed and the effect of recycling waste resources are accelerated.
(2) The method effectively avoids the operation link of extracting and extracting the waste asphalt binder and the regenerated asphalt binder in the traditional method, effectively reduces the possibility of distortion of DOB calculation results caused by the experimental operation errors, and has accurate and effective results.
(3) The method can be suitable for any type of grading, so that the requirements that part of traditional methods need to meet the type of the intermittent grading and define the grading break point are avoided, and the method is scientific and clear.
(4) In the method, during quantization calculation, the RAP 'black stone' effect gradually reaches 100% complete fusion, and the change process of the new-old asphalt interface fusion state accords with a specific functional relation, so that the DOB result under the action of the actual regeneration condition can be subjected to function interpolation calculation by means of a fitting regression formula, and the unscientific and imprecise method that the conventional method adopts single linear function interpolation to perform quantization calculation is avoided.
Additional aspects of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
FIGS. 1 (a) - (b) are schematic diagrams of the interface fusion process of 70# newly added asphalt-RAP waste asphalt respectively;
FIGS. 2 (a) - (b) are schematic diagrams of the interface fusion process of the 90# newly added asphalt-RAP waste asphalt respectively;
FIG. 3 is a schematic diagram of the interface fusion state change of different newly added asphalt-RAP waste asphalt;
FIG. 4 is a graph showing the comparison of the engineering Cheng Gecheng grading and the design composite grading in the example of the present invention;
FIGS. 5 (a) - (f) are graphs showing the physical and mechanical performance index test results (70 # for freshly added asphalt) for the freshly mixed asphalt mixture according to the examples of the present invention;
FIG. 6 is a graph showing the calculation of the degree of new-old asphalt interface fusion (70 # for new asphalt) based on the void fraction index in the example of the present invention;
FIG. 7 is a graph showing the calculation of the degree of new-old asphalt interface fusion (70 # for new asphalt) based on the saturation index in the embodiment of the present invention;
FIGS. 8 (a) - (f) are graphs showing the physical and mechanical performance index test results (90 # for freshly added asphalt) for the freshly mixed asphalt mixture according to the examples of the present invention;
FIG. 9 is a graph showing the calculation of the degree of new-old asphalt interface fusion (90 # for new asphalt) based on the void fraction index in the example of the present invention;
FIG. 10 shows the calculation of the degree of new-old asphalt interface fusion (90 # for new asphalt) based on the saturation index in the example of the present invention.
Detailed Description
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
Embodiments of the invention and features of the embodiments may be combined with each other without conflict.
In one or more embodiments, a method for quantifying the degree of new-old asphalt interfacial fusion based on asphalt mixture properties is disclosed, comprising the steps of:
step (1): preprocessing the waste asphalt pavement material RAP, and determining the synthetic design grading and the optimal asphalt consumption;
specifically, according to the existing design flow of the proportion of the regenerated asphalt mixture, extracting and screening the RAP to obtain the content and the performance of the RAP waste asphalt, the grading of the RAP waste aggregate mixture and other characteristic information; furthermore, the addition proportion of new aggregate mixtures with different particle size grades is obtained through a graphic solution or a planning solution (namely, the synthetic design grading is determined), and the proper new asphalt category and the addition proportion are obtained through a regenerated asphalt binder performance compound formula and a regenerated asphalt mixture road performance test (namely, the optimal asphalt dosage is determined, and if a regenerant is required to be added, the new asphalt is replaced according to the corresponding proportion).
The step completes the design work of the mix proportion composition of the regenerated asphalt mixture, but the fusion degree of the new-old asphalt interface in the regenerated asphalt mixture cannot be quantitatively obtained at the moment.
In this embodiment, the trichloroethylene content in the extracted RAP asphalt should be less than 1% so as not to affect the accuracy of the RAP waste asphalt performance test result.
Step (2): screening out performance indexes capable of being used for quantitatively calculating the fusion degree of a new asphalt interface and an old asphalt interface, and determining the change relation of the performance indexes along with the asphalt consumption;
specifically, according to the types and mutual proportions of the raw materials determined in the step (1), respectively weighing the RAP waste asphalt, the new asphalt and the regenerant (if necessary), and then carrying out mutual miscibility on the materials to prepare the miscible asphalt (the miscible asphalt represents a 100% completely fused state of a new-old asphalt interface).
And (3) respectively weighing the RAP waste aggregate mixture with corresponding quality and the new aggregate mixture with different particle size grades according to the types and the mutual proportions of the raw materials determined in the step (1).
And then preparing a new asphalt concrete sample by adopting three types of asphalt, namely RAP waste asphalt, new asphalt and mixed asphalt, testing physical and mechanical performance indexes of each new asphalt concrete sample under different asphalt dosages by adopting a Marshall compaction test method, and drawing a relation chart of the corresponding performance indexes along with the asphalt dosage.
Finally, the influence effect of different asphalt types (characterized by asphalt PG performance grading) on physical and mechanical performance indexes of the concrete sample is analyzed, and the performance indexes capable of being used for quantitatively calculating the new-old asphalt interface fusion degree are screened out.
In this embodiment, physical and mechanical performance indexes may be selected from the gross bulk density ρ, the test piece void ratio VV, the mineral aggregate void ratio VMA, the asphalt saturation VFA, the stability MS, the flow value FL, and the like, which are involved in the design process of the asphalt mixture mix proportion composition (since road characteristic indexes such as the asphalt mixture high-low temperature performance, the water stability performance, the fatigue performance, and the like are usually only checked under the optimal asphalt dosage, the asphalt dosage is fixed, and thus this type of index is not considered in this embodiment).
Finally, two performance indexes of the void ratio VV and the asphalt saturation VFA are screened out and can be used for quantitatively calculating the new-old asphalt interface fusion degree DOB. Compared with other indexes, the two conventional performance indexes have smaller overall fluctuation of the numerical values along with the performance change of the asphalt PG; meanwhile, the asphalt is changed along with the change of the asphalt consumption in a monotone function, so that the asphalt can be well used for quantifying the content of effective asphalt in the regenerated mixture, and further quantitatively calculating the new-old asphalt interface fusion degree DOB.
Step (3): substituting the performance index into a test result of the performance index of the recycled asphalt concrete sample in an actual recycling state based on the change relation of the performance index along with the asphalt consumption to obtain the content of the effective asphalt in the recycling state;
specifically, in the actual regeneration state, the experimental conditions may include different RAP heating temperatures, new aggregate mixture heating temperatures, total mixing time, and the like under the set experimental conditions.
Substituting the performance index test result p of the regenerated concrete sample in the actual regeneration state in the step (1) according to the change relation of the performance indexes, namely VV and VFA, screened in the step (2) along with the asphalt consumption 2 Determining the effective asphalt content x in the regenerated mixture under the state 2 (x 1 ≤x 2 ≤x 3 )。
Step (4): and combining the effective asphalt content in the 'black stone' state and the 100% complete fusion state of the new-old asphalt interface, and calculating the fusion degree of the new-old asphalt interface in the actual regeneration state through the proportional relation of the black stone state, the new-old asphalt interface and the effective asphalt content.
In particular, the method comprises the steps of,
according to the relation of the performance indexes, namely VV and VFA, screened in the step (2) along with the asphalt dosage, respectively determining the performance index test result p of the reclaimed asphalt mixture in a 'black stone' state and in a 100% complete fusion state of a new-old asphalt interface 1 、p 3 Content x of effective bitumen in each case 1 、x 3 ；
In this example, the effective asphalt content x was first determined for the new-old asphalt interface fusion level at 0% and 100%, respectively 1 And x 3 Based on the relation curve of the performance index with the asphalt consumption, the regenerated asphalt mixture under the corresponding state is obtainedMaterial performance index test result p 1 And p 3 . Wherein, the test result needs to satisfy the following conditions: p is p 1 ≤p 2 ≤p 3 。
Based on the effective asphalt content x in the state of 0% and 100% of the new-old asphalt interface fusion degree 1 And x 3 And obtaining the proportional relation between the new-old asphalt interface fusion degree and the effective asphalt content, and then determining the interface fusion degree in the actual regeneration state according to the effective asphalt content in the actual regeneration state.
The new asphalt described in this example may refer only to newly added asphalt, but if it is necessary to add a recycling agent, the new asphalt contains new asphalt and recycling agent.
The invention can accurately quantify the DOB of the new-old asphalt interface fusion degree, and the technical principle is as follows:
the essence of the DOB parameter is that under the corresponding conditions, the quantity of asphalt with active parts in the RAP material accounts for the proportion of the total quantity of waste asphalt on the surface of the RAP. In the RAP regeneration process, along with the continuous change of the fusion state of the new-old asphalt interface, the quantity of the regenerated asphalt actually effective in the regenerated asphalt mixture and the quality (performance) of the regenerated asphalt are changed, so that the physical, mechanical and other performances of the regenerated asphalt mixture are changed.
At this time, the physical and mechanical properties of the recycled asphalt mixture depend on the influences of the two variables, namely, the change of the physical and mechanical properties of the recycled asphalt mixture may be caused by the effective recycled asphalt quantity, the effective recycled asphalt quality (performance), or both. The existence of double variables can add difficulty to quantitatively calculating the DOB of the new-old asphalt interface fusion degree, and even confuse the real influencing factors behind the physical, mechanical and other performance changes of the regenerated mixture.
Therefore, the quantitative calculation method provided by the invention screens out indexes insensitive to asphalt performance change but sensitive to asphalt dosage change by comparison, so that the influence of the effective regenerated asphalt quantity is obvious and remarkable as much as possible while the influence of the effective regenerated asphalt quality (performance) factor is eliminated.
The technical principle of the present invention can be more vividly clarified by combining the schematic diagrams 1 (a) - (b) and fig. 2 (a) - (b):
fixing the performance and quantity of the waste asphalt on the surface of the RAP, and then adding 70# matrix asphalt and 90# matrix asphalt on the surface of the RAP respectively. Wherein, the addition amount of the 70# matrix asphalt is more than that of the 90# matrix asphalt, and the degree of DOB of the new-old asphalt interface fusion is equal. At this time, the effective fusion quantity of the RAP waste asphalt in the two is consistent, but the fusion quantity of the newly added asphalt is inconsistent (the fusion quantity of the 70# matrix asphalt is more than that of the 90# matrix asphalt), so that the quality (performance) of the effective regenerated asphalt in the two is different, and further the physical, mechanical and other performances of the regenerated asphalt mixture in the two are different. However, it is generally considered that DOB is one of the reasons for influencing the different physical and mechanical properties of the reclaimed asphalt mixture, and thus confusion and even errors are caused. Thus, the present invention needs to first exclude the influence of the change in asphalt quality (performance).
The technical principle of the invention can be more vividly clarified by combining the schematic diagram 3:
the two extreme states, namely a RAP (random access point) state and a 100% complete fusion state of a new-old asphalt interface, are selected, and different change trends such as A, B, C possibly exist in the process of gradually transitioning from the 'black stone' state to the 100% complete fusion state of the new-old asphalt interface. The reason for this is mainly because, inside the reclaimed asphalt mixture, not only the content of effective asphalt (i.e., the amount of asphalt) is gradually changed, but also the performance of effective asphalt (i.e., the quality of asphalt) is gradually changed, and the nature of the degree of new-old asphalt interface fusion DOB is a function of the amount of asphalt. Thus, the present invention needs to first exclude the influence of the change in asphalt quality (performance).
The method of the invention is described below by way of two specific examples.
(1) The novel asphalt is SK-70#A grade road petroleum asphalt, and the specific process comprises the following steps:
step one, combining engineering requirements and the existing design flow of the proportion of the regenerated asphalt mixture, respectively determining the 50% RAP blending proportion and the hot mixing type of the regenerated asphalt mixture, and designing the median value of the upper limit range and the lower limit range of the synthetic grading selection AC-13. Subsequently, characteristic information such as the content of the RAP waste asphalt is 4.8%, the performance grade of the RAP waste asphalt is PG76-16, and the grading composition of the RAP waste aggregate mixture is obtained through an asphalt extraction test and a PG performance grading test, and the test results are shown in Table 1.
Meanwhile, the PG performance grade of the SK-70#A grade asphalt was determined to be PG64-28. The asphalt regenerant is self-made, and the core component of the asphalt regenerant is light aromatic oil (because a certain amount of regenerant is added in the regeneration process in consideration of higher RAP blending proportion).
Furthermore, the addition ratio of the new aggregate mixture (0-5 mm, 5-10 mm, 10-15 mm) with different particle size grades is obtained by a computer planning and solving method, the calculation result is shown in table 1, and the engineering synthesis gradation obtained by compounding is shown in table 1 and fig. 4 (basically the same as the design synthesis gradation).
Finally, according to an asphalt binder performance composite formula (theoretical formula (1)) and an asphalt mixture Marshall test piece performance test result, when the newly added asphalt is SK-70#A grade, the optimum asphalt dosage OAC of the regenerated mixture is 5.6% (the mixing amount of the regenerant is 8% of the total asphalt dosage) and the newly added asphalt is replaced by equal proportion.
Wherein P is the performance of the composite material obtained by mixing different raw materials; p (P) i The performance of each of different raw materials in the composite material; a, a i The composition ratio of the raw materials is different; n is the number of kinds of raw materials.
Table 1: engineering synthesis grading composition table for regenerated asphalt mixture
Step two, according to each raw material type and mutual proportion determined in the step one, calculating with 8 Marshall test piece required quantity (4 to carry out nondestructive physical property test, 4 to carry out destructive mechanical property test) and single test piece quality 1300g (considering material mixing and quality loss in test piece preparation process), wherein the required raw material quality is respectively: 5252g of RAP (5000 g of RAP waste aggregate mixture and 252g of RAP waste asphalt) is needed, 5000g of new aggregate mixture is needed, 314g of SK-70# new asphalt is needed, and 27g of regenerant is needed. And then completely mixing the RAP waste asphalt, the SK-70# newly added asphalt and the regenerant, and manually preparing the mixed asphalt in a state of completely fusing new-old asphalt interfaces. The PG performance grade of the miscible asphalt is PG70-22.
And thirdly, preparing the raw material types and the mutual proportions according to the raw material types determined in the first step, and calculating the raw material quality determined in the second step.
And then, compounding and uniformly mixing the RAP waste aggregate mixture and the newly added aggregate mixture, respectively adopting three types of asphalt of RAP waste asphalt, SK-70# newly added asphalt and miscible asphalt to prepare a new asphalt concrete sample, further testing physical and mechanical performance indexes of each new asphalt concrete sample under different asphalt dosages, drawing a relation chart of corresponding performance indexes along with asphalt dosage changes, and drawing in fig. 5 (a) - (f), wherein fig. 5 (a) - (f) contain all possible states of asphalt performances in the regenerated mixture.
Finally, the influence effect of different asphalt types on the physical and mechanical performance indexes of the asphalt mixture is analyzed, and two conventional performance indexes of the void ratio VV and the asphalt saturation VFA are screened out and can be used for quantitatively calculating the new-old asphalt interface fusion degree DOB.
And step four, averaging test results of the void ratio VV and the asphalt saturation VFA which are conventional performance indexes screened out in the step three under different asphalt types, namely averaging the change curves of the graph 5 (d) and the graph 5 (f), wherein the results are shown in the graph 6 and the graph 7.
Then, the conventional performance index of the regenerated asphalt mixture in the 'black stone' state, namely the void ratio VV, is 9.20 percent, the asphalt saturation VFA is 47.07 percent, and the effective asphalt content in the regenerated mixture is 3.2 percent; similarly, the conventional performance index of the reclaimed asphalt mixture, namely the void ratio VV, is 4.12% and the asphalt saturation VFA is 73.15% in the 100% complete fusion state of the new-old asphalt interface, and at this time, the effective asphalt content in the reclaimed mixture is 5.6%. Further, from the results of the tests of the void ratio and the asphalt saturation of the recycled concrete test piece in the actual recycled state of the first step (the conventional performance index of the recycled asphalt mixture, i.e., the void ratio VV, was 5.50% and the asphalt saturation VFA was 67.26%, which were obtained by the tests in the optimum asphalt amount OAC and the actual recycled state), the effective asphalt contents in the recycled concrete test piece were 4.63% and 4.83%, respectively, in the actual recycled state, which were obtained by substituting the results into fig. 6 and fig. 7 in this order.
Finally, according to the proportion relation of the effective asphalt content in different states (black stone state, 100% complete fusion state and actual regeneration state), the new-old asphalt interface fusion degree DOB is calculated to be 59.6% by the void ratio VV, and the new-old asphalt interface fusion degree DOB is calculated to be 67.9% by the asphalt saturation degree VFA. And taking the average value of the two, and obtaining the DOB of the new-old asphalt interface fusion degree under the condition that the new asphalt is SK-70# to be 63.8%.
(2) The novel asphalt is SK-90#A grade road petroleum asphalt, and the specific process comprises the following steps:
step one, combining engineering requirements and the existing design flow of the proportion of the regenerated asphalt mixture, respectively determining the 50% RAP blending proportion and the hot mixing type of the regenerated asphalt mixture, and designing the median value of the upper limit range and the lower limit range of the synthetic grading selection AC-13. Subsequently, characteristic information such as the content of the RAP waste asphalt is 4.8%, the performance grade of the RAP waste asphalt is PG76-16, and the grading composition of the RAP waste aggregate mixture is obtained through an asphalt extraction test and a PG performance grading test, and the test results are shown in Table 1.
Meanwhile, the PG performance grade of the SK-90#A grade asphalt was determined to be PG58-28. The asphalt regenerant is self-made, and the core component of the asphalt regenerant is light aromatic oil (because a certain amount of regenerant is added in the regeneration process in consideration of higher RAP blending proportion).
Furthermore, the addition ratio of the new aggregate mixture (0-5 mm, 5-10 mm, 10-15 mm) with different particle size grades is obtained by a computer planning and solving method, the calculation result is shown in table 1, and the engineering synthesis gradation obtained by compounding is shown in table 1 and fig. 4 (basically the same as the design synthesis gradation).
Finally, according to an asphalt binder performance composite formula (theoretical formula (1)) and an asphalt mixture Marshall test piece performance test result, when the newly added asphalt is of SK-90#A grade, the optimum asphalt dosage OAC of the regenerated mixture is 5.2% (the mixing amount of the regenerant is 8% of the total asphalt dosage), and the newly added asphalt is replaced by equal proportion.
Step two, according to each raw material type and mutual proportion determined in the step one, calculating with 8 Marshall test piece required quantity (4 to carry out nondestructive physical property test, 4 to carry out destructive mechanical property test) and single test piece quality 1300g (considering material mixing and quality loss in test piece preparation process), wherein the required raw material quality is respectively: 5252g of RAP (5000 g of RAP waste aggregate mixture and 252g of RAP waste asphalt) is needed, 5000g of new aggregate mixture is needed, 273g of SK-90# new asphalt is needed, and 24g of regenerant is needed. And then completely mixing the RAP waste asphalt, the SK-90# newly added asphalt and the regenerant, and manually preparing the mixed asphalt in a state of completely fusing new-old asphalt interfaces. The PG performance grade of the miscible asphalt is PG64-22.
And thirdly, preparing the raw material types and the mutual proportions according to the raw material types determined in the first step, and calculating the raw material quality determined in the second step.
Subsequently, the RAP waste aggregate mixture and the newly added aggregate mixture with the quality are compounded and uniformly mixed, three types of asphalt, namely RAP waste asphalt, SK-90# newly added asphalt and mixed asphalt, are respectively adopted to prepare a new asphalt concrete sample, physical and mechanical performance indexes of each new asphalt concrete sample under different asphalt dosages are tested, a corresponding performance index change relation chart along with the asphalt dosages is drawn, and in fig. 8 (a) - (f), all possible states of asphalt performances in the regenerated mixture are included in fig. 8 (a) - (f).
Finally, the influence effect of different asphalt types on the physical and mechanical performance indexes of the asphalt mixture is analyzed, and two conventional performance indexes of the void ratio VV and the asphalt saturation VFA are screened out and can be used for quantitatively calculating the new-old asphalt interface fusion degree DOB.
And step four, averaging test results of the void ratio VV and the asphalt saturation VFA which are conventional performance indexes screened out in the step three under different asphalt types, namely averaging the change curves of the graph (d) and the graph (f) of fig. 8, wherein the results are shown in the graph (9) and the graph (10).
Then, the conventional performance index of the regenerated asphalt mixture in the 'black stone' state, namely the void ratio VV, is 11.21 percent, the asphalt saturation VFA is 36.47 percent, and the effective asphalt content in the regenerated mixture is 2.8 percent; similarly, the conventional performance index of the reclaimed asphalt mixture, namely the void ratio VV, is 4.61% and the asphalt saturation VFA is 70.55% in the 100% complete fusion state of the new-old asphalt interface, and at this time, the effective asphalt content in the reclaimed mixture is 5.2%. Further, from the results of the tests of the void ratio and the asphalt saturation of the recycled concrete test piece in the actual recycled state of step one (the conventional performance index of the recycled asphalt mixture, i.e., the void ratio VV, was 5.07% and the asphalt saturation VFA was 66.44%, obtained by the test in the optimum asphalt amount OAC and the actual recycled state), the effective asphalt contents in the recycled concrete test piece in the actual recycled state were 4.81% and 4.76%, respectively, obtained by substituting the results into fig. 9 and 10 in this order.
Finally, according to the proportion relation of the effective asphalt content in different states (black stone state, 100% complete fusion state and actual regeneration state), the new-old asphalt interface fusion degree DOB can be calculated to be 83.75% by the void ratio VV, and the new-old asphalt interface fusion degree DOB can be calculated to be 81.67% by the asphalt saturation degree VFA. And taking the average value of the two, and obtaining the DOB (degree of fusion) of the new asphalt interface and the old asphalt interface under the condition that the newly added asphalt is SK-90# is 82.71%.
The above examples are only examples of regeneration which are listed in the present invention and are not intended to limit the method of quantifying the degree of new-old asphalt interfacial fusion DOB in the regenerated mixture. Therefore, the method according to the present invention quantifies the degree of new-old asphalt interface fusion DOB in the regenerated mixture, and any numerical simple modification, correction and equivalent increase and decrease changes made with reference to this example during the quantification are all within the protection scope of the design method according to the present invention.
Claims (8)
1. A method for quantifying the degree of new-old asphalt interface fusion based on asphalt mixture performance, comprising:
the method comprises the following steps of preprocessing the waste asphalt pavement material RAP to determine the synthetic design grading and the optimal asphalt consumption, wherein the concrete process comprises the following steps:
extracting and screening the waste asphalt pavement material RAP to obtain the content and performance of the waste asphalt and the grading of the waste aggregate mixture of the RAP;
obtaining the addition proportion of new aggregate mixtures with different particle size grades through a graphic solution or a planning solution, namely synthesizing design grading;
obtaining new asphalt category and adding proportion, namely the optimal asphalt dosage, through a regenerated asphalt binder performance compound formula and a regenerated asphalt mixture road performance test;
the method comprises the steps of screening out performance indexes capable of being used for quantitatively calculating the fusion degree of a new asphalt interface and an old asphalt interface, and determining the change relation of the performance indexes along with the asphalt dosage, wherein the specific process comprises the following steps:
based on the determined synthetic design grading and the optimal asphalt dosage, preparing a new asphalt concrete sample by adopting three types of asphalt, namely RAP waste asphalt, newly added asphalt and mixed asphalt; wherein the miscible asphalt is prepared by interactive miscibility of RAP waste asphalt and newly added asphalt;
testing physical and mechanical performance indexes of each fresh asphalt concrete sample under different asphalt dosages, and drawing a relation chart of corresponding performance indexes along with the asphalt dosages;
analyzing the influence effect of different asphalt types on the physical and mechanical performance indexes of the concrete sample, and screening out the performance indexes which can be used for quantitatively calculating the fusion degree of the new-old asphalt interface;
substituting the performance index into a test result of the performance index of the recycled asphalt concrete sample in an actual recycling state based on the change relation of the performance index along with the asphalt consumption to obtain the content of the effective asphalt in the recycling state;
and combining the effective asphalt content of the new-old asphalt interface in a 0% fusion state and the effective asphalt content of the new-old asphalt interface in a 100% complete fusion state, and calculating the fusion degree of the new-old asphalt interface in an actual regeneration state through the proportional relation of the three.
2. The method for quantifying the degree of new-old asphalt interface fusion based on asphalt mixture performance according to claim 1, wherein the physical and mechanical performance indexes of each new asphalt concrete sample under different asphalt dosages are tested by a marshall compaction test method.
3. The method for quantifying the degree of new-old asphalt interfacial fusion based on the asphalt mixture performance according to claim 2, wherein the physical and mechanical performance indexes comprise: bulk density ρ, specimen void fraction VV, mineral aggregate void fraction VMA, asphalt saturation VFA, stability MS, and flow value FL.
4. The method for quantifying the degree of new-old asphalt interface fusion based on the asphalt mixture performance according to claim 1, wherein the performance index capable of being used for quantifying and calculating the degree of new-old asphalt interface fusion DOB is screened out, specifically: void fraction VV and asphalt saturation VFA.
5. The method for quantifying the degree of new-old asphalt interface fusion based on asphalt mixture performance according to claim 1, wherein the test result P of the performance index selected by the recycled asphalt concrete sample is determined in a state where the degree of new-old asphalt interface fusion is 0% and in a state where the new-old asphalt interface is 100% completely fused, respectively 1 And P 3 The method comprises the steps of carrying out a first treatment on the surface of the Test result P of performance index of regenerated asphalt concrete sample in actual regenerated state 2 The requirements are satisfied: p (P) 1 ≤P 2 ≤P 3 。
6. The method for quantifying the degree of old-new asphalt interfacial fusion based on asphalt mixture performance according to claim 5, wherein the effective asphalt content x in the state where the degree of old-new asphalt interfacial fusion is 0% and in the state where the old-new asphalt interfacial fusion is 100% is determined, respectively 1 、x 3 The method comprises the steps of carrying out a first treatment on the surface of the Based on the variation relation curve of the selected performance index along with the asphalt dosage, through P 2 Obtaining the effective asphalt content x in the regenerated asphalt concrete sample under the actual regenerated state 2 ，x 2 Needs to satisfy x 1 ≤x 2 ≤x 3 。
7. The method for quantifying the degree of new-old asphalt interfacial fusion based on asphalt mixture properties according to claim 1, wherein the effective asphalt content x is based on the different states 1 、x 2 、x 3 And the mutual proportion relation, and calculating to obtain the new-old asphalt interface fusion degree under the actual regeneration state.
8. The method for quantifying the degree of new-old asphalt interfacial fusion based on asphalt mixture performance according to claim 1, wherein the new asphalt is simply new asphalt or new asphalt and a regenerant.
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