Method for determining mixing amount of anti-icing snow-melting filler based on structure, performance and snow melting effect of asphalt mixture

Abstract

The invention relates to a method for determining the mixing amount of an anti-icing snow-melting filler based on the structure, performance and snow-melting effect of an asphalt mixture, which comprises the following steps of: performing test piece forming on the asphalt mixture with different snow-melting filler mixing amounts, respectively performing density, freeze-thaw splitting and ice-coagulation rate tests, and drawing a double-coordinate-axis curve graph according to the obtained void ratio, freeze-thaw splitting strength ratio and ice-coagulation rate. The void ratio ranges from 2.0% to 3.5%, and the freeze-thaw splitting strength ratio meets gt; the ice coagulation rate is smaller than 55%, and meanwhile, the range meeting the conditions is the target mixing amount range of the snow melting filler. The evaluation method provided by the invention can effectively determine the range of the addition amount of the snow melting filler in the snow melting asphalt mixture, so that the snow melting asphalt mixture meets the normal pavement performance requirements of an asphalt pavement while ensuring the snow melting effect.

Description

Technical Field

[0001] This invention relates to a method for determining the dosage of anti-icing and snow-melting filler based on the structure, performance, and snow-melting effect of asphalt mixtures, belonging to the field of highway asphalt pavement design technology. Background Technology

[0002] Road construction and operation are crucial components of the national economy, playing a vital role in its development. Ensuring smooth traffic flow and road safety are two major challenges in road operation. This is especially true in large cities where traffic congestion is increasingly severe, where road service capacity becomes a decisive factor affecting the normal functioning of the city.

[0003] In cold winter weather, roads are prone to snow and ice accumulation, leading to ice and snow disasters. This causes problems such as reduced road surface adhesion, vehicle skidding, and loss of steering control, often resulting in traffic congestion or even paralysis. Therefore, it is necessary to adopt various measures and methods to clear snow and ice from roads. While maintaining good road quality to provide sufficient service capacity, it is also necessary to increase road safety to prevent traffic accidents caused by severe weather.

[0004] Snow-melting asphalt pavement incorporates snow-melting materials during pavement construction. Over long-term use, these materials slowly release snow, effectively melting accumulated snow on the road surface. It not only offers advantages such as proactive, efficient, and bottom-up snow and ice melting, but also provides continuous and sustained snow and ice melting, avoiding the adverse effects of using large amounts of snow-melting agents. Furthermore, it improves the efficiency of snow and ice melting under vehicle loads.

[0005] However, in practical applications, the amount of snow-melting filler added to asphalt mixtures is not necessarily better the more the better. Studies show that snow-melting filler has an adverse effect on the water stability of the mixture. Water damage, along with rutting and cracking, is one of the three most significant forms of pavement distress in my country across all grades of asphalt pavement. Insufficient water resistance in asphalt mixtures can lead to potholes, seriously affecting driving safety. Therefore, the amount of snow-melting filler added should be controlled within a certain range to ensure that the asphalt mixture meets both the requirements for active snow melting and road performance. Summary of the Invention

[0006] The purpose of this invention is to provide a method for determining the amount of snow-melting filler in snow-melting asphalt mixtures. This method is based on the structure, performance and snow-melting effect of asphalt mixtures, and solves the problems that adding too much snow-melting filler affects the water stability performance of snow-melting asphalt mixtures, while adding too little snow-melting filler fails to achieve the active snow-melting effect.

[0007] The specific solution of the present invention is as follows:

[0008] A method for determining the dosage of anti-icing and snow-melting filler based on the structure, performance and snow-melting effect of asphalt mixtures, including test steps for specimen molding, density, freeze-thaw splitting and ice-freezing rate, and evaluation steps for the dosage of snow-melting filler.

[0009] The specimen molding steps are as follows:

[0010] Specimens were formed according to the test methods in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" T0702-2011.

[0011] The density detection step is as follows:

[0012] The test was conducted according to the test method of "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" T0705-2011, and the porosity of the specimen was calculated.

[0013] The freeze-thaw crack detection steps are as follows:

[0014] The test was conducted according to the test method of "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" T0729-2000, and the freeze-thaw splitting strength ratio of the specimen was calculated.

[0015] The freezing rate detection steps are as follows:

[0016] A cylinder of a fixed size is fixed to the upper surface of the specimen using water-insoluble sealant. A certain amount of distilled water is injected into it, and the specimen is placed in an environmental chamber with constant temperature conditions for freezing. After a period of time, the distilled water in the cylinder is removed, weighed, and the freezing rate is calculated according to the following formula.

[0017] s = (m0 - m) ÷ m0 × 100%

[0018] in:

[0019] s: Freezing rate

[0020] m0: Mass of injected water

[0021] m: Mass of remaining water

[0022] The method for evaluating the snow melting filler content is as follows:

[0023] Asphalt mixtures with different snow-melting filler contents were subjected to density, freeze-thaw splitting tensile strength, and freezing rate tests. Based on the obtained porosity, freeze-thaw splitting tensile strength ratio, and freezing rate, a dual-axis curve was plotted. The porosity curve was used to determine the snow-melting filler content range C1 corresponding to a porosity of 2.0% to 3.5%. The freeze-thaw splitting tensile strength ratio curve was used to determine the snow-melting filler content range C2 corresponding to a freeze-thaw splitting tensile strength ratio > 80%. The freezing rate curve was used to determine the snow-melting filler content range C3 corresponding to a freezing rate < 55%. The snow-melting filler content C in the overlapping part of C1, C2, and C3 is the target content range.

[0024] In the specimen molding process, the molded specimen is a standard specimen with dimensions of φ101.6mm×63.5mm, and the number of compaction times is 50 times on each side.

[0025] In the density test, during the process of weighing the specimen in water, the specimen should not be immersed in water for more than 3 minutes.

[0026] In the freezing rate test, the diameter of the fixed-size cylinder is 6cm, the amount of distilled water injected is 30ml, and the freezing time is 60min.

[0027] The method for determining the content of snow-melting filler in this invention considers a porosity of 2.0%~3.5%, a freeze-thaw splitting strength ratio >80%, and an ice-freezing rate <55%. The solution obtained by simultaneously meeting these three requirements is that the snow-melting filler content C in the overlapping portion of C1, C2, and C3 is the target content range. These three indicators represent the structure, water stability, and snow-melting effect of the asphalt mixture, respectively. Because the snow-melting filler gradually precipitates during the application of the asphalt mixture, it affects the internal porosity structure of the mixture. The water stability has the greatest impact on the road performance of the asphalt mixture after the addition of snow-melting filler. The snow-melting asphalt mixture must not only ensure the basic performance of the mixture but also provide anti-icing and snow-melting effects. Therefore, this invention determines the snow-melting filler content based on these three indicators. Only when all three indicators are met can the asphalt mixture achieve structural stability, meet water stability requirements, and provide good anti-icing and snow-melting effects. With a porosity in the range of 2.0% to 3.5%, the internal structure of the mixture remains stable after the snow-melting filler is released; with a freeze-thaw splitting strength ratio in the range of >80%, the strength of the mixture still meets the requirements under freeze-thaw conditions; and with a freezing rate in the range of <55%, the surface of the snow-melting asphalt mixture will not freeze into a hard ice layer within 1 hour in a low-temperature environment, and the road surface will not slip under the simultaneous action of vehicle loads.

[0028] The evaluation method of this invention can effectively determine the range of snow-melting filler content in snow-melting asphalt mixture, so that the snow-melting asphalt mixture can meet the normal road performance requirements of asphalt pavement while ensuring the snow-melting effect. Attached Figure Description

[0029] Figure 1 This is a curve graph with two axes. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the embodiments, and the invention includes, but is not limited to, the contents of the embodiments.

[0031] Based on the actual engineering needs, different dosages of snow-melting filler in asphalt mixtures are determined, and the following steps are performed on asphalt mixtures with different dosages of snow-melting filler.

[0032] The evaluation method steps of this invention are as follows:

[0033] (1) Specimens were formed according to the test method of "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" T0702-2011. The formed specimens were standard specimens with a size of φ101.6mm×63.5mm and were compacted 50 times on each side. The asphalt mixture mix ratio is as follows: salts (a mixture of organic and inorganic salts) purchased from the market for anti-icing and snow melting are added to the mixture.

[0034] Table 1. AC-13 Grading Curve

[0035] Sieve aperture size (mm) 16 13.2 9.5 4.75 2.36 1.18 0.6 0.3 0.15 0.075 Grading (%) 100 95 70 43.5 27.5 18 12.5 8.5 7 6

[0036] (2) The density was tested according to the test method of T0705-2011 "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering". During the process of weighing the specimen in water, the specimen was immersed in water for no more than 3 minutes; the porosity of the specimen was calculated.

[0037] (3) The freeze-thaw splitting test was carried out according to the test method of "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" T0729-2000, and the freeze-thaw splitting strength ratio of the specimen was calculated.

[0038] (4) Fix a 6cm diameter cylinder to the upper end of the specimen with water-insoluble sealant. Weigh the mass m0 of 30ml of distilled water in advance, pour 30ml of distilled water into the cylinder, and freeze the specimen in an environmental chamber with constant temperature conditions. After 60min, take out the distilled water in the cylinder and weigh it m. Calculate the freezing rate according to the following formula.

[0039] s = (m0 - m) ÷ m0 × 100%

[0040] in:

[0041] s: Freezing rate

[0042] m0: Mass of injected water

[0043] m: Mass of remaining water

[0044] The experimental results are shown in Table 1.

[0045] Table 2 Test Results of Snow Melting Asphalt Mixture

[0046] Snow melting filler content (%) Porosity (%) Freeze-thaw splitting strength ratio (%) Freezing rate (%) 0 4.1 93.4 62 2 3.4 87.0 57 4 2.9 83.2 49 6 2.5 79.8 43 8 2.2 71.7 39

[0047] (5) Density and freeze-thaw splitting tests were conducted on asphalt mixtures with different snow-melting filler contents. The resulting porosity, freeze-thaw splitting strength ratio, and freezing rate were plotted as follows: Figure 1As shown, the porosity curve indicates that the snow melting filler content range is ≥2% when the porosity is in the range of 2.0~3.5. The freeze-thaw splitting strength ratio curve indicates that the snow melting filler content range is ≤5% when the freeze-thaw splitting strength ratio is >80%. The freezing rate curve indicates that the snow melting filler content range is ≥3% when the freezing rate is <55%. The overlapping part, i.e. the target content range of snow melting filler, is 3%~5%.

Claims

1. A method for determining the dosage of anti-icing and snow-melting filler based on the structure, performance, and snow-melting effect of asphalt mixtures. Asphalt mixtures with different filler dosages were molded into specimens, and density, freeze-thaw splitting tensile strength, and freezing rate tests were conducted. Based on the obtained porosity, freeze-thaw splitting tensile strength ratio, and freezing rate, dual-axis curves were plotted. The porosity curve determined the filler dosage range C1 corresponding to a porosity of 2.0%–3.5%. The freeze-thaw splitting tensile strength ratio curve determined the dosage corresponding to a freeze-thaw splitting tensile strength ratio >80%. The snow melting filler dosage range is C2. The snow melting filler dosage range corresponding to an ice freezing rate < 55% is determined as C3. The snow melting filler dosage range C in the overlapping area of ​​C1, C2, and C3 is the target dosage range. The test method for the ice freezing rate is as follows: a fixed-size cylinder is fixed to the upper end face of the specimen using water-insoluble sealant. A certain amount of distilled water is injected into the cylinder, and it is placed in an environmental chamber with constant temperature conditions for freezing. After a period of time, the liquid distilled water in the cylinder is removed, weighed, and the ice freezing rate is calculated according to the following formula: s = (m0 - m) ÷ m0 × 100% in: s: freezing rate m0: Mass of injected water m: The mass of the remaining liquid water.

2. The method according to claim 1, wherein the diameter of the fixed-size cylinder is 6cm, the amount of distilled water injected is 30ml, and the freezing time is 60min.

3. The method according to claim 1, wherein the density test is conducted according to the test method of "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" T0705-2011, and the void ratio of the specimen is calculated.

4. According to claim 3, in the density test, during the process of weighing the specimen in water, the specimen is immersed in water for no more than 3 minutes.

5. The method according to claim 1, wherein the freeze-thaw splitting test is conducted according to the test method of "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" T0729-2000, and the freeze-thaw splitting strength ratio of the specimen is calculated.

6. The method according to claim 1, wherein the specimen is prepared according to the test method of "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" T0702-2011.

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