Quantitative evaluation method for adhesion between rubber powder modified asphalt and aggregate

Abstract

The present application belongs to the technical field of road materials, and relates to a method for quantitatively evaluating the adhesion of rubber powder modified asphalt and aggregate, which comprises the following steps: 1) forming asphalt mixture by mixing rubber powder modified asphalt and aggregate; 2) performing layer-by-layer elution on the asphalt mixture by using solvent elution method, and collecting eluted asphalt of each layer; 3) calculating the dispersion degree improvement range of each layer of eluted asphalt based on the rubber powder modified asphalt and each layer of eluted asphalt; 4) determining the contribution weight of each layer of eluted asphalt to adhesion by using the grey correlation method; 5) obtaining adhesion evaluation index according to the dispersion degree improvement range and the contribution weight; and 6) obtaining the adhesion performance grade according to the size of the adhesion evaluation index, and completing the quantitative evaluation of adhesion. The present application can objectively, directly and quantitatively evaluate the adhesion of rubber powder modified asphalt and aggregate, and has the characteristics of high evaluation precision and strong cross-scale correlation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of road materials, and relates to a method for quantitatively evaluating the adhesion performance of rubber powder modified asphalt and aggregate. BACKGROUND

[0002] The rapid development of the rubber industry has generated a large amount of waste rubber. According to statistics, the residual amount of waste rubber tires can reach more than 20 million tons, forming serious "black pollution". In order to realize sustainable development, waste rubber needs to be recycled. At present, in the road traffic industry, waste rubber is mainly made into rubber particles as a modifier to prepare rubber powder modified asphalt. After a series of physical and chemical actions of rubber powder and asphalt, the asphalt and its mixture are greatly improved in performance, the service life of asphalt pavement is prolonged, the black environmental pollution is reduced, and the production cost is reduced, which has good development prospects and environmental benefits. However, when the rubber powder modified asphalt is mixed with aggregate for road construction, the incorporation of rubber powder makes the interface behavior of asphalt binder and aggregate complex. The interfacial adhesion performance of rubber powder modified asphalt with different aggregate is different under different rubber powder particle size, dosage and asphalt types. Therefore, the adhesion performance between rubber powder modified asphalt and aggregate needs to be evaluated. However, the existing evaluation of the adhesion performance of asphalt aggregate still adopts the water boiling and water immersion method. This method mainly depends on the naked eye to judge the degree of asphalt peeling on the surface of aggregate. The test operation and result evaluation are highly subjective, and the human factors have a great influence.

[0003] In recent years, with the development of micro characterization technology, a batch of micro evaluation methods such as gel permeation chromatography (GPC), fourier transform infrared absorption spectrum analysis (FITR), dynamic shear rheometer (DSR) and atomic force microscope (AFM) have emerged. However, the evaluation objects are only general asphalt or emulsified asphalt. The specific quantitative relationship of the adhesion between rubber powder modified asphalt and aggregate at different layer thicknesses is still unclear. There is still no set of effective and accurate quantitative evaluation method for the adhesion of rubber powder modified asphalt and aggregate. SUMMARY

[0004] The purpose of the application is to provide a method for quantitatively evaluating the adhesion performance of rubber powder modified asphalt and aggregate, which can objectively, directly and quantitatively evaluate the adhesion of rubber powder modified asphalt and aggregate, and has the characteristics of high evaluation precision and strong cross-scale correlation.

[0005] In order to achieve the above purpose, the technical scheme adopted by the application is:

[0006] A method for quantitatively evaluating the adhesion performance of rubber powder modified asphalt and aggregate, comprising the following steps:

[0007] 1) forming asphalt mixture by mixing rubber powder modified asphalt and aggregate;

[0008] 2) using solvent elution method to elute the asphalt mixture layer by layer, collecting each layer of elution asphalt;

[0009] 3) using liquid chromatography method, calculating the dispersion degree improvement range Q of each layer of elution asphalt respectively for the crumb rubber modified asphalt and each layer of elution asphalt j ;

[0010] 4) obtaining the pull-off strength between the crumb rubber modified asphalt and the aggregate, and combining the dispersion degree improvement range Q j , using the grey correlation method to determine the contribution weight ω of each layer of elution asphalt to the adhesion performance j ;

[0011] 5) obtaining the adhesion evaluation index Q j according to the dispersion degree improvement range Q j and the contribution weight ω S ;

[0012] 6) obtaining the adhesion performance grade according to the size of the adhesion evaluation index Q S , completing the adhesion quantitative evaluation.

[0013] Further, the step 1) specifically comprises:

[0014] 1.1) preparing crumb rubber modified asphalt;

[0015] 1.2) mixing and stirring the crumb rubber modified asphalt and the aggregate at a mass ratio of 1:20 for 200s-240s at a temperature of 160-170℃;

[0016] 1.3) after the stirring is completed, placing and curing at room temperature for 21 days to obtain the asphalt mixture.

[0017] Further, the preparation process of the crumb rubber modified asphalt in the step 1.1) is: after the base asphalt is heated at 150-160℃ for 1h, the crumb rubber particles are added for pre-modification for 30min; then shearing modification is carried out at 180-195℃ for 50-60min at a speed of 3000r / min to obtain the crumb rubber modified asphalt.

[0018] Further, in the step 2), the solvent used for layer-by-layer elution is trichloroethylene, toluene, tetrahydrofuran, decalin or decahydronaphthalene.

[0019] Further, the step 3) specifically comprises:

[0020] 3.1) obtaining the corresponding test samples after the crumb rubber modified asphalt and each layer of elution asphalt are pretreated respectively;

[0021] 3.2) Using a Waters high performance liquid chromatography system, the molecular weight of each test sample of step 3.1) is obtained; the molecular weight includes the number average molecular weight and the weight average molecular weight, and the molecular weight is calculated according to the following formula:

[0022]

[0023]

[0024] Wherein:

[0025] M i is the molecular weight of the i-th molecule of the test sample, n i is the proportion of the i-th molecule of the test sample in the total number of molecules, M n is the number average molecular weight of the test sample, M w is the weight average molecular weight of the test sample;

[0026] 3.3) Calculate the dispersity PD0 of the crumb rubber modified asphalt and the dispersity PD j of each layer of elution asphalt; j Both PD0 and PD j are calculated according to the following formula:

[0027]

[0028] Wherein: j is the number of elution layers, j = 1, 2, 3, 4... n;

[0029] 3.4) Calculate the dispersity improvement range Q j of each layer of elution asphalt, which is calculated according to the following formula:

[0030]

[0031] Further, in step 3.1), the pretreatment includes centrifugation, rotary evaporation and drying; the rotary evaporation conditions are: temperature 60℃, rotation speed 50r / min, and time 45min.

[0032] Further, step 4) specifically includes:

[0033] 4.1) Set the comparison sequence and the reference sequence;

[0034] The dispersity improvement range Q j of each layer of elution asphalt is taken as the comparison sequence {X j (k)}, and the pull-out strength of the crumb rubber modified asphalt and the aggregate is taken as the reference sequence {Y j (k)};

[0035] k is the sample number of the mixture of the rubber powder modified asphalt and aggregate, k = 1, 2, 3... m; j is the number of elution layers, j = 1, 2, 3, 4... n;

[0036] 4.2) Reference sequence is dimensionless processed with comparison sequence;

[0037]

[0038] Wherein: X' j (k) represents the comparison sequence after dimensionless processing; X j (1) represents the first row data in the comparison sequence;

[0039] The reference sequence Y j (k) is processed by the method of referring to the comparison sequence, to obtain the reference sequence Y' j (k) after dimensionless processing;

[0040] 4.3) Calculate the absolute difference matrix Δ j (k)

[0041] Δ j (k) = |Y' j (k) - X' j (k) |;

[0042] 4.4) Calculate the maximum difference A and the minimum difference I;

[0043]

[0044]

[0045] 4.5) Calculate the grey correlation coefficient ξ of the reference sequence and the calculation sequence j (k);

[0046]

[0047] In the formula, ρ is a resolution coefficient, and the value is between 0 and 1;

[0048] 4.6) Calculate the grey correlation degree r of the reference sequence and the calculation sequence j ;

[0049]

[0050] In the formula, m is the total number of sample number k of the asphalt mixture;

[0051] 4.7) The correlation degree is normalized, and the contribution weight ω of the jth layer asphalt to the adhesion performance between asphalt and aggregate is calculated according to the following formula j ;

[0052]

[0053] In the formula: n is the total number of elution layers j.

[0054] Further, Q S Calculated according to the following formula:

[0055]

[0056] Where: j is the number of elution layers, j = 1, 2, 3, 4... n, n is the total number of elution layers j.

[0057] Further, the adhesion performance grade in step 6) is divided as follows:

[0058] Q S In [1.0, 1.5), the adhesion performance is first grade; Q S In [1.5, 2.0), the adhesion performance is second grade; Q S In [2.0, 2.5), the adhesion performance is third grade; Q S ≥2.5, the adhesion performance is fourth grade.

[0059] Further, in step 6), Q S The greater, the stronger the adhesion performance.

[0060] The beneficial effects of the present application are:

[0061] 1、 The present application proposes a quantitative evaluation method for the adhesion performance of rubber powder modified asphalt and aggregate, compared with the existing qualitative evaluation method, which characterizes the adhesion performance between asphalt and mineral aggregate in the form of specific numerical values, the evaluation results are objective and fair, and overcome the defects of strong subjectivity and interference of human factors in the existing evaluation method.

[0062] 2、 The evaluation method of the present application can realize the detailed differentiation of the adhesion performance of rubber powder modified asphalt and aggregate under the same adhesion grade, and compared with the traditional water immersion method, the evaluation means is fine and scientific, and the differentiation degree is high.

[0063] 3、 The present application starts from the conversion degree of asphalt molecular weight and chemical substances in the interface adhesion process, proposes a rubber powder modified asphalt adhesion evaluation index based on layer-by-layer elution to characterize the compactness of the interface internal structure of rubber powder modified asphalt, and evaluates the adhesion quality of different asphalt and mineral aggregate interfaces, the present application establishes the connection between the micro molecular level and the macro adhesion performance, the evaluation precision is high, the evaluation index has strong correlation with the adhesion performance, and provides a new idea for the establishment of the rubber powder modified asphalt adhesion performance evaluation system.

[0064] 4, The present application has important significance for revealing the internal factors and action mechanism of the adhesion performance of the crumb rubber modified asphalt and aggregate, analyzing the material migration change rule of the adhesion process, and laying a theoretical foundation for improving the durability of the crumb rubber modified asphalt pavement and widely applying the crumb rubber modified asphalt. BRIEF DESCRIPTION OF DRAWINGS

[0065] Figure 1 is a flow chart of the crumb rubber modified asphalt and aggregate adhesion performance quantitative evaluation method based on layer-by-layer elution of embodiments of the present application;

[0066] Figure 2 is a crumb rubber modified asphalt elution schematic diagram of the present application;

[0067] Figure 3 is a comparison diagram of different elution methods of the crumb rubber modified asphalt of the present application;

[0068] Figure 4 is a crumb rubber modified asphalt equal quality layer-by-layer elution operation diagram of embodiments of the present application;

[0069] Figure 5 is the solvent elution uniformity test result of embodiments of the present application. DETAILED DESCRIPTION

[0070] The technical solutions of the present application will be described in detail in combination with the drawings and embodiments.

[0071] Referring to Figure 1 , a crumb rubber modified asphalt and aggregate adhesion performance quantitative evaluation method of the present application includes the following steps.

[0072] 1) Forming crumb rubber modified asphalt and aggregate into asphalt mixture.

[0073] This step specifically includes:

[0074] 1.1) Preparing crumb rubber modified asphalt: after the base asphalt is heated at 150℃-160℃ for 1h, crumb rubber particles are added and pre-modified for 30min; then, in a constant temperature oil bath pot at 180℃-195℃, a high-speed shearing machine is used to shear at a speed of 3000r / min for 50min-60min, to obtain crumb rubber modified asphalt.

[0075] 1.2) At a temperature of 160℃-170℃, crumb rubber modified asphalt and aggregate are mixed and stirred at a mass ratio of 1:20 for 200s-240s.

[0076] 1.3) After the stirring is completed, the asphalt mixture is obtained by placing and curing at room temperature for 21 days.

[0077] 2) Using solvent elution method to perform layer-by-layer elution on the asphalt mixture, and collecting the elution asphalt of each layer.

[0078] In this step, the solvent used for layer-by-layer elution is trichloroethylene, toluene, tetrahydrofuran, naphthane, or decahydronaphthalene. Trichloroethylene is the preferred solvent.

[0079] 3) For the rubber-modified asphalt and each layer of eluted asphalt, the corresponding increase in dispersion Q of each layer of eluted asphalt was calculated using liquid chromatography. j .

[0080] This step specifically includes:

[0081] 3.1) The rubber-modified asphalt and each layer of washed asphalt were pretreated to obtain corresponding test samples.

[0082] Pretreatment includes centrifugation, rotary evaporation, and drying; the conditions for rotary evaporation are: temperature 60℃, rotation speed 50 r / min, and time 45 min.

[0083] 3.2) Using a Waters high-performance liquid chromatography system, the molecular weight of each test sample in step 3.1) was obtained. Molecular weight includes number-average molecular weight and weight-average molecular weight, calculated according to the following formula:

[0084]

[0085]

[0086] in:

[0087] M i To test the molecular weight of the i-th molecule in the sample, n i To test the proportion of the i-th type of molecule in the total number of molecules, M n M is the number-average molecular weight of the test sample. w This represents the weight-average molecular weight of the test sample.

[0088] 3.3) Calculate the dispersion PD0 of the rubber-modified asphalt and the dispersion PD of each layer of washed asphalt. j ;PD0 and PD j The following formulas are used for calculation:

[0089]

[0090] Where: j is the number of elution layers, j = 1, 2, 3, 4...n;

[0091] 3.4) Calculate the increase in dispersion Q of each layer of washed bitumen. j Calculate according to the following formula:

[0092]

[0093] 4) Obtain the pull strength between the crumb rubber modified asphalt and the aggregate, and combine the dispersion improvement range Q j Determine the contribution weight ω of each layer of elution asphalt to the adhesion between the crumb rubber modified asphalt and the aggregate by using the grey correlation method j .

[0094] Step 4) specifically includes:

[0095] 4.1) Set the comparison sequence and the reference sequence;

[0096] The dispersion improvement range Q of each layer of elution asphalt j is taken as the comparison sequence {X j (k)} and the pull strength between the crumb rubber modified asphalt and the aggregate is taken as the reference sequence {Y j (k)}.

[0097] k is the sample number of the asphalt mixture formed by the crumb rubber modified asphalt and the aggregate, k = 1, 2, 3... m; j is the layer number of elution, j = 1, 2, 3, 4... n.

[0098] 4.2) Non-dimensional treatment is performed on the reference sequence and the comparison sequence;

[0099]

[0100] Wherein: X′ j (k) represents the comparison sequence after non-dimensional treatment; X j (1) represents the first row of data in the comparison sequence.

[0101] The reference sequence Y j (k) is processed by referring to the comparison sequence to obtain the reference sequence Y′ j (k) after non-dimensional treatment.

[0102] 4.3) Calculate the absolute difference matrix Δ j (k)

[0103] Δ j (k) = |Y′ j (k) - X′ j (k);

[0104] Wherein: j is the layer number of elution, j = 1, 2, 3, 4... n; k = 1, 2, 3... m.

[0105] 4.4) Calculate the maximum difference A and the minimum difference I;

[0106]

[0107]

[0108] j is the number of elution layers, j = 1, 2, 3, 4...n; k = 1, 2, 3...m.

[0109] 4.5) Calculate the grey correlation coefficient ξ of the reference sequence and the calculation series j (k);

[0110]

[0111] In the formula, ρ is the resolution coefficient, which is between 0 and 1; j = 1, 2, 3, 4...n, k = 1, 2, 3...m.

[0112] 4.6) Calculate the grey correlation degree r of the reference sequence and the comparison sequence j ;

[0113]

[0114] In the formula: m is the total number of sample quantities k of the asphalt mixture.

[0115] 4.7) Normalize the correlation degree, and calculate the contribution weight ω of the jth layer elution asphalt to the adhesion performance between the asphalt aggregate according to the following formula j ;

[0116]

[0117] In the formula above: n is the total number of elution layers j, j = 1, 2, 3, 4...n.

[0118] 5) According to the dispersion degree improvement amplitude Q j and the contribution weight ω j , the adhesion evaluation index Q of the rubber powder modified asphalt is obtained S .

[0119] Q S is calculated according to the following formula:

[0120]

[0121] In the formula above: j is the number of elution layers, j = 1, 2, 3, 4...n; n is the total number of elution layers j.

[0122] 6) According to the size of the adhesion evaluation index Q S , the adhesion performance grade is obtained, and the adhesion quantitative evaluation is completed.

[0123] In this step, the larger Q S , the tighter the combination between the asphalt and the aggregate, and the more excellent the adhesion performance.

[0124] Further, according to Q SThe adhesion performance of the rubber powder modified asphalt and the aggregate is divided into the following four grades with an interval of 0.5, corresponding to poor, general, good and excellent adhesion performance, respectively, to obtain a quantitative evaluation system of the adhesion performance of the rubber powder modified asphalt based on layer-by-layer elution, as shown in Table 1.

[0125] Table 1 Quantitative evaluation system of the adhesion performance of the rubber powder modified asphalt based on layer-by-layer elution

[0126] Q S ]] [1.0，1.5) [1.5，2.0) [2.0，2.5) ≥2.5 Adhesion rating First Second Third Fourth

[0127] The adhesion performance quantitative evaluation method of the present application is further illustrated below with specific examples.

[0128] Example

[0129] S1: Preparation of rubber powder modified asphalt and aggregate asphalt mixture

[0130] (1) Preparation of rubber powder modified asphalt

[0131] The base asphalt is placed in an oven at 150°C for 1 hour, and the corresponding mass fraction of waste rubber powder particles is added for pre-modification for 30 minutes. The shearing modification is performed at a high-speed shearing machine speed of 3000 r / min and an oil bath pot temperature of 175°C for 50 minutes to complete the preparation of the rubber powder modified asphalt.

[0132] In this example, the mass fraction of the rubber powder is 10%, 15% and 20%; and the mesh number of the rubber powder is 40 mesh, 60 mesh and 80 mesh (see Table 3).

[0133] (2) Preparation of asphalt mixture

[0134] First, 1000g of aggregate with the same particle size range (in this example, 13mm-19mm) is weighed and placed in a stirring pot at 160°C, and 50g of rubber powder modified asphalt is added to the pot. After stirring for 240s, the rubber powder modified asphalt mixture is obtained. Finally, the mixture is placed in a normal temperature environment for 21 days to ensure the full adhesion of the rubber powder modified asphalt and the aggregate. The asphalt mixture after curing can be subjected to the layer-by-layer elution experiment.

[0135] In the implementation, the base asphalt is 90# asphalt and 70# asphalt; and the aggregate is granite.

[0136] S2: Layer-by-layer elution of asphalt mixture

[0137] In the layer-by-layer elution of the asphalt mixture, the elution solvent and the elution method can ensure the uniformity of the layer-by-layer elution, and provide a good basis for subsequent dispersion index acquisition and adhesion evaluation, so the elution solvent and the elution method are optimized.

[0138] In order to select a suitable solvent for the crumb rubber modified asphalt, the solvent should not only have a good ability to dissolve the asphalt components, but also ensure the uniformity of the asphaltene, gum, saturates and aromatic solubility during the dissolution process, and the preferential dissolution of a certain component is not allowed. Meanwhile, the solvent should not dissolve the crumb rubber particles to avoid the existence of crumb rubber components in the asphalt dissolution solution after elution, and to avoid the influence of crumb rubber components on the test results. Therefore, the Hansen solubility parameters of asphalt with five solvents, including trichloroethylene, toluene, tetrahydrofuran, decalin and ten hydrogen naphthalene, were compared, and the results are shown in Table 2.

[0139] Table 2 Hansen solubility parameters of asphalt with different solvents

[0140] Solvent Asphaltic concrete Soft asphalt Trichloroethylene 3.96 14.72 Toluene 8.98 18.97 Tetrahydrofuran 2.70 31.82 Naphthene 26.91 40.97 Decalin 63.28 60.73

[0141] At present, the methods of layer-by-layer elution test include equal mass elution and equal time elution. The former selects different elution times to elute the asphalt mixture layer by layer, so as to ensure that the mass of the eluted asphalt layers is not much different. The latter selects a fixed elution time, and divides the number of layers equal to the number of elution times to elute layer by layer. The mass of the asphalt layers obtained by this method may be quite different.

[0142] Further, in order to compare the elution effects of the two elution methods, the equal mass elution and equal time elution methods were carried out on the crumb rubber modified asphalt and the mixture prepared with granite, and four layers were eluted.

[0143] During the test, the process of the elution method is shown in Figure 2 . The equal mass elution and equal time elution were used. The equal mass elution is that the mass of the eluted asphalt is equal each time. The equal time elution method selects the elution time of each time as 1 min, and four layers of asphalt are obtained by eluting four times. The elution results of the two elution methods are shown in Figure 3 .

[0144] Referring to Figure 3 , the mass distribution of each layer obtained by the equal time elution method is extremely unreasonable, and the mass difference between the first layer and the fourth layer is 60.1%. The inner layer asphalt which plays an adhesive performance is difficult to be completely eluted in 1 min, which leads to a large mass deviation of the asphalt and a large difficulty in recovery. The mass proportions of each asphalt layer obtained by the equal mass elution method at different times are 25.8%, 24.4%, 25.5% and 24.3% respectively, and the maximum mass and minimum mass difference is only 1.5%. The mass deviation of the asphalt layer is small, and the aggregate surface shows no asphalt adhesion after the fourth layer is dissolved for 28 min. The asphalt recovery is almost equal to 100%.

[0145] Therefore, the embodiment selects the layer-by-layer equal quality elution method to recycle the asphalt adhered to the aggregate surface, ensures the same elution quality of each asphalt layer, and avoids affecting the subsequent dispersion test.

[0146] Further, according to the equal quality elution result, the layer-by-layer elution time of the first layer to the fourth layer is determined as 10s, 25s, 55s and 28min respectively, so that the elution can ensure that the mass difference of each type of asphalt mixture is the smallest.

[0147] Further, in order to ensure the uniformity of the equal quality eluted asphalt, a steel ball is used to replace the aggregate to test the uniformity of the equal quality elution, and the result is shown in Figure 5

[0148] Referring to Figure 5 , the mass difference between the asphaltenes, colloid, aromatic fraction and saturated fraction of the eluted asphalts of each layer is 0.9%, 1.2%, 1.6% and 0.5% respectively, and the four-component proportion of each layer is relatively small compared with the four-component proportion of the modified asphalt before elution. Therefore, the solvent selectivity dissolution does not exist when the asphalt adhered to the surface of the aggregate is eluted by using trichloroethylene solvent, and the equal quality elution method proposed in the embodiment is applicable to the elution of the rubber powder modified asphalt mixture.

[0149] In the embodiment, the equal quality layer-by-layer elution is adopted, the elution solvent is trichloroethylene, and the steps of the equal quality elution and the elution time of each layer are shown in Figure 4

[0150] Referring to Figure 4 , in the first layer (the outermost layer) elution, 200g of the asphalt mixture after curing is placed in a 0# beaker, 500ml of trichloroethylene is added for fully dissolving for 10s, the liquid in the 0# beaker is poured into a 1# beaker through a filter screen to obtain the first layer eluted asphalt, and the residue in the 0# beaker is continuously subjected to the second layer elution.

[0151] In the second layer elution, 500ml of trichloroethylene is continuously added to the residue in the 0# beaker for fully dissolving for 25s, then the liquid is poured into a 2# beaker through a filter screen to obtain the second layer eluted asphalt, and the residue in the 0# beaker is continuously subjected to the third layer elution.

[0152] In the third layer asphalt elution, 500ml of trichloroethylene is continuously added to the residue in the 0# beaker for fully dissolving for 55s, then the liquid is poured into a 3# beaker through a filter screen to obtain the third layer eluted asphalt, and the residue in the 0# beaker is continuously subjected to the fourth layer elution.

[0153] In the fourth layer asphalt elution, 500ml of trichloroethylene is continuously added to the residue in the 0# beaker for fully dissolving for 28min, at this time, it is ensured that the fourth layer (the innermost layer) asphalt can be completely eluted, then the liquid is poured into a 4# beaker through a filter screen to obtain the fourth layer eluted asphalt.​​

[0154] S3: Gel permeation chromatography test (GPC) of each layer of eluted asphalt

[0155] When performing the chromatography test, the four eluted asphalts obtained by layer-by-layer elution need to be immediately pretreated to ensure the performance of the modified asphalt. The pretreatment steps are as follows.

[0156] First, centrifugal tests are performed on the solutions in the four beakers to reduce the impact of the rubber powder particles and asphalt insoluble substances on subsequent tests. Then, the solutions after centrifugation are placed in a 60°C oil bath for rotary evaporation tests in batches, with a rotation rate of 50 r / min. After 45 min of rotary evaporation, each layer of asphalt is obtained. Finally, each layer of asphalt after rotary evaporation is placed in a drying box for 3 hours to ensure that the trichloroethylene can be completely removed, avoiding the impact of other chemicals on subsequent experiments.

[0157] The gel chromatography test in this embodiment uses a Waters high-performance liquid chromatography (HPLC) system.

[0158] The main test specifications of the system are as follows: the instrument measurement standard is polystyrene resin, the particle size of the test chromatography column is 5 μm, and the pore size is The solvent reagent selected during the test is tetrahydrofuran, with a flow rate of 1 mL / min. The temperature of the chromatography column is maintained at 35°C, and the column pressure is stabilized at 625 PSI.

[0159] Specifically, the rubber powder modified asphalt not adhered to the aggregate, the first layer of eluted asphalt, the second layer of eluted asphalt, the third layer of eluted asphalt, and the fourth layer of eluted asphalt are respectively prepared for GPC testing. The sample preparation method is as follows: 25 mg of rubber powder modified asphalt or base asphalt sample is weighed using a microbalance, and the sample is dissolved in 5 ml of tetrahydrofuran solvent. The dissolution time is 24 hours. Then, after baseline leveling and related processing of the test instrument, the dissolved GPC test sample is injected into the system for test testing.

[0160] The molecular weight statistical results of each test sample can be obtained through the GPC test. The dispersity PD0 of the rubber powder modified asphalt not adhered to the aggregate and the dispersity PD of each layer of eluted asphalt can be calculated according to formulas (1), (2), and (3). j wherein: j is the number of elution layers, satisfying j = 1, 2, 3, 4... n, which can be selected according to actual needs.

[0161] In this embodiment, the number of elution layers is 4, so j takes 1, 2, 3, and 4, respectively, to obtain the dispersity results of the first, second, third, and fourth layer of eluted solution, PD0 and PD jAll are calculated by the following formula:

[0162]

[0163]

[0164]

[0165] Wherein, M i is the molecular weight of the i th molecule, n i is the proportion of the i th molecule in the total number of molecules, M n is the number average molecular weight, M w is the weight average molecular weight, PD x is the dispersity; the test sample refers to the crumb rubber modified asphalt or each layer elution asphalt as the GPC test sample.

[0166] Based on the crumb rubber modified asphalt adhesion evaluation index of each layer elution, the improvement range of the dispersity of each layer elution asphalt compared with the dispersity of the initial crumb rubber modified asphalt is calculated.

[0167] Specifically, the dispersity PD0 of the crumb rubber modified asphalt not adhered to the aggregate and the dispersity PD j of each layer elution asphalt are used to calculate the dispersity improvement range Q j of each layer elution asphalt, and the calculation method is shown in formula (4).

[0168]

[0169] In this embodiment, 18 samples of crumb rubber modified asphalt with different mass fractions and crumb rubber mesh numbers and granite asphalt mixture are used for equal mass layer-by-layer elution to obtain the dispersity improvement range of each layer elution asphalt, and the results are shown in Table 3.

[0170] S4: Determination of the contribution weight of each elution layer asphalt to the adhesion performance between asphalt aggregate

[0171] The contribution weight ω j of each elution layer asphalt to the adhesion performance between asphalt aggregate is determined.

[0172] Preferably, in this embodiment, the gray correlation method is used to determine the contribution weight of each layer, and the specific determination steps are as follows.

[0173] (1) Define the comparison sequence and the reference sequence.

[0174] In this embodiment, the comparison sequence is the dispersity improvement range of the first layer to the fourth layer elution asphalt, i.e., Q1, Q2, Q3 and Q4 form the comparison sequence {X1(k)},{X2(k)},{X3(k)},{X4(k)}.

[0175] In this embodiment, j is the number of elution layers, j is 1-4.

[0176] Meanwhile, according to the existing research, the pull strength can better represent the adhesion strength between asphalt and aggregate. In this embodiment, the pull strength of the crumb rubber modified asphalt and aggregate (granite is selected in this embodiment) is selected as the reference sequence. The results are shown in Table 3, i.e., {X0(k)} k = 1, 2, 3... m.

[0177] In this embodiment, k represents the sample number of the mixture of crumb rubber modified asphalt and aggregate. According to Table 3, k is 1-m, and m = 18.

[0178] Further, the pull strength test of the crumb rubber modified asphalt and granite aggregate is performed by using the PosiTest AT-A full-automatic digital display pull-type adhesion tester produced by the DeFelsko company of the United States. The asphalt film thickness is 800 μm. Three sets of repetitive tests are performed for each group of test pieces to ensure the test accuracy. The loading temperature is room temperature, and the loading rate is 0.7 MPa / s.

[0179] (2) The reference sequence and the comparison sequence are subjected to dimensionless processing.

[0180] Since the meanings of various factors in the system are different, the data dimensions may be deviated. Therefore, when the grey correlation method is used for analysis, the data needs to be subjected to dimensionless processing.

[0181]

[0182] X′ j (k) represents the comparison sequence after dimensionless processing; X j (1) represents the first row data in the comparison sequence.

[0183] The reference sequence Y j (k) is processed by referring to the method of the comparison sequence to obtain the reference sequence Y′ j (k) after dimensionless processing.

[0184] (3) Calculate the absolute difference matrix.

[0185] According to formula (6), the absolute difference Δ j (k) of the two comparison sequences at k time is calculated, so as to obtain the matrix.

[0186] Δ j (k) = |Y′ j (k) - X′ j (k) | (6)

[0187] (4) Calculate the maximum difference A and the minimum difference I.

[0188]

[0189]

[0190] (5) Calculate the grey correlation coefficient of the reference sequence and the calculation series.

[0191] The correlation coefficient of the two at different times can be calculated by formula (9).

[0192]

[0193] In the formula, ρ is the resolution coefficient, which is usually limited to the range of 0-1, and commonly selected as 0.5.

[0194] (6) Calculate the grey correlation degree r of the reference sequence and the comparison sequence j .

[0195]

[0196] In the formula: j takes 1-4, k takes 1-m, and m=18.

[0197] According to the correlation degree r j , after normalization processing, the contribution weight of the jth layer (j takes 1-4) elution asphalt to the adhesion performance between asphalt and aggregate can be calculated, as shown in formula (11).

[0198]

[0199] In the formula: j takes 1-n, and n=4.

[0200] In this embodiment, the tensile strength of the 18 combined samples and the dispersion degree improvement range (i.e. Q1, Q2, Q3 and Q4) of the elution asphalt of each layer are sequentially substituted into the above steps, respectively, to obtain the contribution weight calculation results of the jth layer (j takes 1-4) elution asphalt to the adhesion performance between asphalt and aggregate, as shown in Table 4.

[0201] Table 3 Tensile test results and dispersion degree of different rubber powder modified asphalts and granite

[0202]

[0203] Table 4 Contribution weight of elution asphalt of each layer to adhesion performance

[0204]

[0205]

[0206] S5: Quantitative evaluation of adhesion performance of rubber powder modified asphalt based on layer-by-layer elution

[0207] The contribution weight ω of each layer of elution asphalt to the adhesion performance determined according to step S4 j , and the dispersion improvement range Q of each layer of elution asphalt j , the adhesion performance evaluation index Q based on layer-by-layer elution is calculated S , as shown in formula (12).

[0208]

[0209] In this embodiment, the data in Tables 3 and 4 are substituted into formula (12) to calculate the Q S value of 70# rubber powder modified asphalt and granite is 1.608, the Q S value of 90# rubber powder modified asphalt and granite is 1.552. Compared with Table 1, the adhesion levels are both secondary, and the adhesion performance of 70# rubber powder modified asphalt and granite is better than that of 90# rubber powder modified asphalt and granite.

Claims

1. A method for quantitatively evaluating the adhesion performance of asphalt modified with adhesive powder to aggregates, characterized in that, Includes the following steps: 1) The modified asphalt powder is mixed with aggregates to form an asphalt mixture; 2) The asphalt mixture is eluted layer by layer using a solvent elution method, and the eluted asphalt from each layer is collected; 3) For the rubber-modified asphalt and each layer of eluted asphalt, the corresponding increase in dispersion of each layer of eluted asphalt was calculated using liquid chromatography. ; Calculate the dispersibility of rubber-modified asphalt. and the dispersion of each layer of eluted bitumen ; and The following formulas are used for calculation: in: j The number of layers eluted. ; M n To determine the number-average molecular weight of the test samples, M w The weight-average molecular weight of the test sample; Calculate the increase in dispersion of each layer of washed bitumen. Calculate according to the following formula: ； 4) Obtain the pull-out strength between the rubber-modified asphalt and the aggregate, and combine it with the dispersion to improve the yield. The grey relational analysis method was used to determine the contribution weight of each layer of eluted bitumen to the adhesion performance. ; Step 4) specifically includes: 4.1) Define the comparison sequence and the reference sequence; Increase the dispersion of each layer of washed bitumen As a comparison sequence { The pull-out strength of the modified asphalt and aggregates is used as a reference sequence. }; k This refers to the sample size of asphalt mixtures formed from rubber-modified asphalt and aggregates. ; j The number of layers eluted. ; 4.2) The reference and comparison sequences are dimensionless; in: This represents the comparison sequence after dimensionless processing; This indicates a comparison of the first row of data in the sequence; Processing the reference sequence using the method of comparing sequences The dimensionless reference sequence is obtained. ; 4.3) Calculate the absolute difference matrix ； 4.4) Calculate the maximum difference A and the minimum difference I ; 4.5) Calculate the grey relational coefficient between the reference sequence and the calculated series. ; In the formula, The resolution coefficient takes a value between 0 and 1; 4.6) Calculate the grey relational degree between the reference sequence and the comparison sequence. ; In the above formula: m Number of samples of asphalt mixture k The total number; 4.7) After normalizing the correlation degree, calculate the first correlation degree according to the following formula. j Weight of the contribution of layer-washed asphalt to the inter-aggregate adhesion properties ; In the above formula: n Elution layer number j The total number of floors; 5) Based on the increase in dispersion and contribution weight Obtain adhesion evaluation index ; 6) Based on adhesion evaluation indicators The size of the adhesive properties determines the level of adhesion performance, thus completing the quantitative evaluation of adhesion.

2. The method for quantitatively evaluating the adhesion performance of rubber-modified asphalt to aggregates according to claim 1, characterized in that, Step 1) specifically includes: 1.1) Preparation of rubber powder modified asphalt; 1.2) At a temperature of 160℃~170℃, mix the rubber-modified asphalt and aggregate at a mass ratio of 1:20 for 200s~240s. 1.3) After mixing, let it cure at room temperature for 21 days to obtain asphalt mixture.

3. The method for quantitatively evaluating the adhesion performance of rubber-modified asphalt to aggregates according to claim 2, characterized in that, The preparation process of the rubber powder modified asphalt in step 1.1) is as follows: after heating the base asphalt at 150℃~160℃ for 1 hour, rubber powder particles are added for pre-modification for 30 minutes; then, at 180℃~195℃, it is sheared at a speed of 3000 r / min for 50 minutes~60 minutes to obtain rubber powder modified asphalt.

4. The method for quantitatively evaluating the adhesion performance of rubber-modified asphalt to aggregates according to claim 3, characterized in that, In step 2), the solvent used for layer-by-layer elution is trichloroethylene, toluene, tetrahydrofuran, or naphthalene.

5. The method for quantitatively evaluating the adhesion performance of rubber-modified asphalt to aggregates according to claim 4, characterized in that, Step 3) specifically includes: 3.1) After pretreatment, the rubber-modified asphalt and each layer of washed asphalt were obtained as corresponding test samples; 3.2) Using a Waters high-performance liquid chromatography system, obtain the molecular weight of each test sample from step 3.1); the molecular weight includes number-average molecular weight and weight-average molecular weight, and the molecular weight is calculated according to the following formula: in: M i For the test sample i The molecular weight of the molecule n i For the test sample i The percentage of each type of molecule in the total number of molecules. M n To determine the number-average molecular weight of the test samples, M w This represents the weight-average molecular weight of the test sample.

6. The method for quantitatively evaluating the adhesion performance of rubber-modified asphalt to aggregates according to claim 5, characterized in that, In step 3.1), the pretreatment includes centrifugation, rotary evaporation and drying; the conditions for rotary evaporation are: temperature 60℃, rotation speed 50r / min, and time 45min.

7. The method for quantitatively evaluating the adhesion performance of rubber-modified asphalt to aggregates according to claim 1, characterized in that, In step 5) The following formula is used to calculate: in: j The number of layers eluted. ; n Elution layer number j The total number of floors.

8. The method for quantitatively evaluating the adhesion performance of rubber-modified asphalt to aggregates according to claim 7, characterized in that, The adhesion performance levels in step 6) are classified as follows: Within the range [1.0, 1.5), the adhesion performance is Grade 1; At [1.5, 2.0), the adhesion performance is grade two; At [2.0, 2.5), the adhesion performance is level three; ≥2.5, adhesion performance is level four.

9. The method for quantitatively evaluating the adhesion performance of rubber-modified asphalt to aggregates according to claim 8, characterized in that, In step 6), The larger the size, the stronger the adhesion.

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