Method for rapidly predicting freezing fracture temperature of mixture based on low-temperature mechanical properties of asphalt

Abstract

The invention belongs to the technical field of performance prediction of hydraulic engineering materials, and provides a method for rapidly predicting the freezing fracture temperature of a mixture based on low-temperature mechanical properties of asphalt, and the method comprises the steps: collecting mechanical property parameters of ultralow-temperature modified hydraulic asphalt in a low-temperature tensile state, and calculating the corresponding yield strain energy of the ultralow-temperature modified hydraulic asphalt; based on the yield strain energy, a prediction model of the freezing fracture temperature of the asphalt mixture is constructed, and the prediction model meets the following relational expression I: y represents the freezing fracture temperature of the asphalt mixture; x represents average yield strain energy; and training and verifying the prediction model based on the formula series sample set for testing the performance of the ultralow-temperature modified hydraulic asphalt so as to finish error analysis, thereby obtaining the rapid prediction model for the freezing fracture temperature of the asphalt mixture. The method is high in universality and can realize rapid prediction.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of water conservancy engineering material performance prediction, and in particular to a method for rapidly predicting the freeze break temperature of asphalt mixture based on the low-temperature mechanical properties of asphalt. BACKGROUND

[0002] With the rapid development of social and economic modernization and the proposal of the "double carbon" target, the requirement for environmental protection is becoming higher and higher, and the development of various clean energy is becoming more and more important. Among them, water resources play an important role in clean energy, therefore, increasing the rational development and utilization of water resources to meet the strategic goal of China's development.

[0003] Compared with other impervious materials, hydraulic asphalt concrete has better viscoelasticity, plasticity, ductility and flexibility, and is widely used in water conservancy construction as the impervious layer of hydraulic structures such as dam panels, core walls and seawalls. With the construction of pumped storage power stations in high-cold regions and high-altitude regions, the low-temperature crack resistance of hydraulic asphalt concrete is required to be higher, therefore, in order to adapt to the requirements of special application environment and solve the problem of easy cracking of hydraulic asphalt at low temperature, it is particularly important to develop low-temperature crack-resistant hydraulic asphalt suitable for use in high-cold regions.

[0004] The low-temperature crack resistance of hydraulic asphalt mixture (such as core wall and impervious layer) is a key indicator, and the equipment currently used to detect this key indicator has the problems of complex operation, single function and low evaluation efficiency. The direct detection method of traditional asphalt mixture freeze break test needs to prepare mixture test pieces for low-temperature freeze break test (such as below-30℃), which has the defects of long time consumption (7-15 days), high cost and strict equipment requirements. In addition, due to the interference of factors such as aggregate gradation and mix proportion, it is difficult to directly relate the performance of asphalt to the performance of asphalt, therefore, special equipment is needed for detection.

[0005] In view of the deficiencies of the above direct detection method, relevant technical personnel has developed various indirect detection methods for low temperature performance of asphalt mixture. For example, the patent with publication number CN114636622B discloses an evaluation method for low temperature crack resistance of asphalt mixture based on equivalent fracture temperature. In view of the problem that the existing evaluation index, i.e., fracture energy, cannot effectively distinguish the low temperature crack resistance of recycled asphalt mixture, a new evaluation index, i.e., equivalent fracture temperature, is derived based on the fracture energy. The fracture energy and bending modulus of the asphalt mixture are obtained through the beam bending test of the asphalt mixture, the thermal shrinkage coefficient of the asphalt mixture is obtained through the thermal shrinkage test of the asphalt mixture or through the thermal shrinkage coefficient model of the asphalt mixture, and the equivalent fracture temperature of the asphalt mixture is calculated according to the above parameters. The equivalent fracture temperature is used as the evaluation standard for the low temperature crack resistance of the asphalt mixture, thereby improving the distinguishability of the low temperature crack resistance of the asphalt mixture. However, the fracture energy, bending modulus and thermal shrinkage coefficient in the method are all mixture parameters, and the test object is the asphalt mixture specimen, so the mixture needs to be formed and cured, and the beam bending test needs to be performed, which has a long test cycle, a complicated process and a long time consumption, and cannot achieve the purpose of rapid prediction.

[0006] For example, the patent with publication number CN103232711B discloses a low temperature hydraulic asphalt which is composed of heavy duty asphalt, rubber powder, SBS modifier, compatibility agent and stabilizer. The amount of each component is 60-75 parts by weight of heavy duty asphalt, 5-15 parts of rubber powder, 3.8-10 parts of SBS modifier, 12-26 parts of compatibility agent and 0.2-0.3 parts of stabilizer. The softening point of the low temperature hydraulic asphalt is greater than 70℃, the 5℃ ductility is greater than 55cm, the penetration is greater than 100, the brittle point is lower than -25℃, and the low temperature freeze break of the mixture reaches -45℃, which can meet the special requirements of hydraulic asphalt in high-cold regions. A detection method for replacing the low temperature freeze break temperature of the low temperature hydraulic asphalt mixture is also disclosed. The test results of the bending beam rheometer of the low temperature hydraulic asphalt sample are used to characterize the low temperature freeze break temperature of the asphalt sample mixture. However, the detection method depends on the specific chemical formula of the asphalt, has low universality, has a long overall test cycle, and cannot achieve the purpose of rapid prediction. SUMMARY

[0007] In view of the above-mentioned shortcomings of the prior art, the present application provides a method for rapidly predicting the freeze break temperature of the mixture of asphalt based on the low temperature mechanical properties of the asphalt, which has high universality and can achieve rapid prediction.

[0008] To achieve the above and related purposes, the present application adopts the following technical solutions:

[0009] A method for rapidly predicting the freeze break temperature of the mixture of asphalt based on the low temperature mechanical properties of the asphalt, comprising the following steps:

[0010] (1) Collect the mechanical property parameters of the super-low temperature modified water conservancy asphalt in a low-temperature tensile state and calculate the corresponding yield strain energy; further, in step (1)

[0011] (2) Based on the yield strain energy, a freeze break temperature prediction model of the asphalt mixture is constructed, and the prediction model satisfies the following relationship I:

[0012] ,

[0013] In the relationship I, y represents the freeze break temperature of the asphalt mixture, and the unit is ℃; x represents the average yield strain energy, and the unit is N·cm;

[0014] (3) Based on the sample set of the super-low temperature modified water conservancy asphalt performance test formula series, the prediction model is trained and verified to complete error analysis, and a freeze break temperature rapid prediction model of the asphalt mixture is obtained.

[0015] Further, in step (1), the yield strain energy calculation method comprises:

[0016] (relationship II),

[0017] In the relationship II, E represents the yield strain energy, and the unit is N·cm; F max represents the yield point tension of the super-low temperature modified water conservancy asphalt in a low-temperature tensile state, and the unit is N; L max represents the yield point displacement of the super-low temperature modified water conservancy asphalt in a low-temperature tensile state, and the unit is cm.

[0018] Further, the average yield strain energy is the average value of multiple groups of yield strain energy.

[0019] Further, in step (2), the freeze break temperature prediction model of the asphalt mixture is constructed by the least square method.

[0020] Further, in step (3), the sample set of the super-low temperature modified water conservancy asphalt performance test formula series has at least 20 groups of samples, and the formulas are different.

[0021] Further, when the ductility test of the water conservancy asphalt mixture is carried out by the freeze break temperature rapid prediction model of the asphalt mixture, the test time is not more than 3h.

[0022] Further, in step (1), the low-temperature tensile state comprises: the temperature is 4±0.1℃.

[0023] Further, in step (1), the low-temperature tensile state further comprises: the tensile speed is 10±1 mm / min.

[0024] The beneficial technical effects of the present application are:

[0025] This invention uses the low-temperature mechanical properties of ultra-low temperature modified hydraulic asphalt itself as the most sensitive parameter for predicting the freezing point of its mixture, so as to directly determine the low-temperature deformation adaptability of hydraulic asphalt mixture through its own stress relaxation ability.

[0026] This invention establishes a quantitative mathematical model, namely a rapid prediction model for the freezing-break temperature of asphalt mixtures. By measuring the low-temperature yield strain energy, a key mechanical parameter of ultra-low temperature modified hydraulic asphalt, the freezing-break temperature of the mixture can be predicted quickly and accurately. This method can complete the asphalt force ductility test in just 3 hours, replacing the traditional freezing-break test of mixtures that takes more than 7 days, greatly improving testing efficiency and solving the problem of the time-consuming nature of traditional methods.

[0027] This invention is applicable to ultra-low temperature modified hydraulic asphalt prepared with various different formulations, and has high versatility. Furthermore, this invention is applicable to rapid quality inspection of asphalt materials upon arrival at the site, low-temperature adaptability design of hydraulic seepage prevention structures, and performance optimization of asphalt supplier products. It solves the efficiency bottleneck of low-temperature performance evaluation of hydraulic asphalt mixtures, provides real-time data support for engineering material selection, and has significant economic value.

[0028] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0029] The accompanying drawings, incorporated in and forming part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without inventive effort. In the drawings:

[0030] Figure 1 This is a curve showing the deformation amount versus tensile force of the specimen in this application. Detailed Implementation

[0031] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should be understood that certain features of the invention (described in the context of separate embodiments for clarity) may also be provided in a single embodiment. Conversely, multiple features of the invention (described in the context of a single embodiment for brevity) may also be provided separately or in any suitable combination or, where appropriate, in any other described embodiment of the invention. Certain features described in the context of various embodiments will not be considered essential features of those embodiments unless the embodiment is inoperable without those elements. The invention is further illustrated below by specific examples; however, it should be noted that the specific process conditions and results described in the embodiments of the invention are merely illustrative and should not be construed as limiting the scope of protection of the invention. All equivalent changes or modifications made in accordance with the spirit and essence of the invention should be covered within the scope of protection of the invention.

[0032] This invention provides a method for rapidly predicting the frost fracture temperature of asphalt mixtures based on their low-temperature mechanical properties, comprising the following steps:

[0033] (1) Collect the mechanical property parameters of ultra-low temperature modified hydraulic asphalt under low temperature tensile state and calculate its corresponding yield strain energy.

[0034] Furthermore, in this step, the low-temperature tensile condition includes: a temperature of 4±0.1℃, a tensile speed of 10±1 mm / min, and mechanical property parameters including yield point tensile force F. max Yield point displacement L max .

[0035] Further, in this step, a force-ductility tester is used to test the mechanical properties of ultra-low temperature modified hydraulic asphalt under low-temperature tensile conditions. The force-ductility tester consists of a ductility meter and tensile force and deformation measuring devices. The ductility meter should meet the requirements of the Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering T 0605. The tensile force and deformation measuring devices can measure, display, and record tensile force and ductility values ​​in real time. The tensile force measuring device has a range of 0~300N and an accuracy of ±0.1N, while the deformation measuring device has an accuracy of ±1mm. The ductility test is conducted according to the Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering, with a test temperature of 4℃ and an accuracy of ±0.1℃, and a tensile speed of 10mm / min and an accuracy of ±1mm / min. Finally, a specimen deformation-tensile force curve is plotted, as shown below. Figure 1 As shown, the yield point tensile force and yield point tensile amount are obtained.

[0036] Furthermore, in this step, the method for calculating the yield strain energy includes:

[0037] (Relationship II)

[0038] In Equation II, E represents the yield strain energy, with units of N·cm; F max L represents the yield strength of ultra-low temperature modified hydraulic asphalt under low temperature tensile conditions, expressed in N; max This indicates the yield point displacement of ultra-low temperature modified hydraulic asphalt under low temperature tensile conditions, in cm.

[0039] Furthermore, this application uses the arithmetic mean of multiple yield strain energies as the average yield strain energy, accurate to 0.1 N·cm. These multiple groups can be up to three, etc. The average yield strain energy represents the stress relaxation capability of the ultra-low temperature modified hydraulic asphalt, i.e., its adaptability to low-temperature deformation.

[0040] (2) Based on the yield strain energy, a prediction model for the freezing fracture temperature of asphalt mixture is constructed. The prediction model satisfies the following relationship I:

[0041] ,

[0042] In Equation I, y represents the freezing point of the asphalt mixture, in °C; x represents the average yield strain energy, in N·cm.

[0043] Furthermore, in this step, a prediction model for the freezing point temperature of asphalt mixtures is constructed using the least squares method. Even further, this application quantifies the quantitative relationship between the average yield strain energy of the ultra-low temperature modified hydraulic asphalt matrix and the freezing point temperature of the hydraulic asphalt mixture by fitting a linear equation, ensuring that this relationship reflects the overall trend of all data points. This application pre-prepares no fewer than 20 sets of ultra-low temperature modified hydraulic asphalt samples with different formulations. For each set of samples, its yield point tensile force and yield point displacement are simultaneously measured to calculate the average yield strain energy and the actual freezing point temperature of the mixture made from that ultra-low temperature modified hydraulic asphalt sample, thus forming multiple sets of data pairs. The least squares method is applied for fitting to obtain the prediction model for the freezing point temperature of the asphalt mixture.

[0044] (3) Based on the sample set of formulations for testing the performance of ultra-low temperature modified hydraulic asphalt, the prediction model is trained and verified to complete the error analysis and obtain a rapid prediction model for the freezing temperature of asphalt mixture.

[0045] Furthermore, in this step, the sample set of formulations used for performance testing of ultra-low temperature modified hydraulic asphalt comprises at least 20 groups of samples, each with a different formulation. Even further, the preparation method of ultra-low temperature modified hydraulic asphalt in this application can utilize existing technology, obtaining multiple different formulations by changing different parameter proportions. For example, the ultra-low temperature modified hydraulic asphalt of this application is prepared by the following method:

[0046] (3.1) Mix the solvent and modifier, and swell at a constant temperature for a certain time to obtain a premix.

[0047] The swelling conditions are as follows: swelling temperature is 175°C-185°C, stirring speed is 200 r / min-1000 r / min, and stirring time is 0.5h-1h.

[0048] The solvent is a composition of aromatic oil and naphthenic oil, and the weight ratio of aromatic oil to naphthenic oil is 1:(1-10):1, preferably, the weight ratio of aromatic oil to naphthenic oil is 5:(1-7):1;

[0049] The modifier is one or more combinations of SBS, SBR, SEBS, and desulfurized rubber particles; when the modifier is a combination of SBR and SEBS, the weight ratio between the two is 3:1; when the modifier is a combination of SBS, SBR, and SEBS, the weight ratio between the three is 4:2:1; when desulfurized rubber particles are used in the modifier, the desulfurized rubber particles account for no less than 10% of the total amount of the modifier.

[0050] (3.2) The premix and the base asphalt are sheared by a shearing machine to obtain intermediate material.

[0051] The shearing conditions are as follows: shearing temperature 175°C-185°C, shearing time 0.5h-1h.

[0052] (3.3) The stabilizer, plasticizer and phase change agent are mixed and stirred to develop, and then ultra-low temperature modified hydraulic asphalt is obtained.

[0053] The stabilizer is a combination of thiuram vulcanization accelerator and sulfur, with a weight ratio of 1:1.

[0054] The plasticizer is one of phthalates, fatty acids, fatty acid esters, and polyols;

[0055] The phase change agent is a blend of Fischer-Tropsch wax and polyethylene glycol 400 in a weight ratio of 2:1.

[0056] Furthermore, this application obtains a series of sample formulations for performance testing of ultra-low temperature modified hydraulic asphalt by changing the weight parts of the base asphalt, solvent, modifier, stabilizer, plasticizer, and phase change agent. For example:

[0057] Sample 1 of this application: The base bitumen is bitumen produced from straight-run naphthenic crude oil, sourced from Shandong Jingbo Petrochemical Co., Ltd., 100 parts by weight, penetration 130 dmm; 9 parts modifier; 0.3 parts stabilizer; 0.5 parts plasticizer; 0.5 parts phase change agent; 6 parts solubilizer.

[0058] Sample 2 of this application: 100 parts by weight of base bitumen; 25 parts of modifier; 0.3 parts of stabilizer; 0.5 parts of plasticizer; 1 part of phase change agent; 8 parts of solvent.

[0059] Sample 3 of this application: 100 parts by weight of base bitumen; 6 parts of modifier; 0.3 parts of stabilizer; 0.5 parts of plasticizer; 1 part of phase change agent; 7 parts of solvent.

[0060] Sample 4 of this application: 100 parts by weight of base bitumen; 14 parts of modifier; 0.3 parts of stabilizer; 0.5 parts of plasticizer; 0.5 parts of phase change agent; 6 parts of solvent.

[0061] This application does not list all samples; the preparation principle is the same as above, only the weight parts of the components are changed.

[0062] Furthermore, this application trains and validates the prediction model to complete error analysis and evaluate the reliability of the prediction model. The evaluation metrics include the correlation coefficient R. 2 R measures how well a model explains the variability of data. 2 A value > 0.99 indicates an extremely high model fit and highly reliable predictions. Mean absolute error (MAE) or root mean square error (RMSE): quantifies the average deviation between the model's predicted values ​​and the actual values. Furthermore, after establishing the prediction model, this application validates it using a sample set not used in training to ensure its generalization ability and prevent overfitting. Upon successful validation, a rapid prediction model for the freezing point temperature of asphalt mixtures is obtained, which can be used for prediction. That is, for any new ultra-low temperature modified hydraulic asphalt sample, as long as its low-temperature average yield strain energy x is measured and substituted into the prediction model, the predicted freezing point temperature y of its mixture can be calculated.

[0063] Furthermore, this application uses a series of sample sets of formulations for testing the performance of ultra-low temperature modified hydraulic asphalt to train and validate the prediction model. The validation results of the above samples 1 to 4 are shown in Table 1.

[0064] Table 1

[0065]

[0066] Furthermore, the correlation coefficient R of the prediction model in this application... 2 The correlation is >0.99, indicating a very strong correlation and high prediction reliability; the verification error is controlled within ±2℃, meeting the accuracy requirements for engineering applications.

[0067] Furthermore, when conducting ductility tests on hydraulic asphalt mixtures using a rapid prediction model for asphalt mixture freezing-break temperature, the testing time does not exceed 3 hours. This application can complete asphalt force ductility testing in just 3 hours, replacing the traditional 7-day or longer freezing-break test of mixtures, significantly improving testing efficiency and solving the problem of the time-consuming nature of traditional methods.

[0068] Furthermore, the method of this application is applicable to ultra-low temperature modified hydraulic asphalt prepared with various different formulations, and has high versatility. In addition, this application is applicable to rapid quality inspection of asphalt materials upon arrival at the site, low temperature adaptability design of hydraulic seepage prevention structures, and performance optimization of asphalt supplier products. It solves the efficiency bottleneck of low temperature performance evaluation of hydraulic asphalt mixtures, provides real-time data support for the selection of engineering materials, and has significant economic value.

[0069] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for rapidly predicting the freeze-thaw fracture temperature of asphalt mixtures based on their low-temperature mechanical properties, characterized in that, Includes the following steps: (1) Collect the mechanical property parameters of ultra-low temperature modified hydraulic asphalt under low temperature tensile state and calculate its corresponding yield strain energy. (2) Based on the yield strain energy, a prediction model for the freezing fracture temperature of asphalt mixture is constructed. The prediction model satisfies the following relationship I: ， In Equation I, y represents the freezing point of the asphalt mixture, in °C; x represents the average yield strain energy, in N·cm. (3) Based on the sample set of formulations for testing the performance of ultra-low temperature modified hydraulic asphalt, the prediction model is trained and verified to complete the error analysis and obtain a rapid prediction model for the freezing temperature of asphalt mixture.

2. The method according to claim 1, characterized in that, In step (1), the method for calculating the yield strain energy includes: (Relationship II) In Equation II, E represents the yield strain energy, with units of N·cm; F max The L represents the yield point tensile force of the ultra-low temperature modified hydraulic asphalt under low temperature tensile conditions, in N; max The value represents the yield point displacement of the ultra-low temperature modified hydraulic asphalt under low temperature tensile conditions, in cm.

3. The method according to claim 2, characterized in that, The average yield strain energy is the average of multiple sets of yield strain energies.

4. The method according to claim 2, characterized in that, In step (2), the asphalt mixture freezing temperature prediction model is constructed using the least squares method.

5. The method according to claim 3, characterized in that, In step (3), the sample set of the formula series for testing the performance of ultra-low temperature modified hydraulic asphalt has at least 20 groups of samples, and the formulas are different.

6. The method according to claim 4, characterized in that, When the ductility test of hydraulic asphalt mixture is performed using the rapid prediction model for freezing fracture temperature of asphalt mixture, the test time shall not exceed 3 hours.

7. The method according to claim 1, characterized in that, In step (1), the low-temperature stretching state includes a temperature of 4±0.1℃.

8. The method according to claim 1, characterized in that, In step (1), the low-temperature stretching state further includes a stretching speed of 10±1 mm / min.

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