Method for rapidly measuring content of emulsified asphalt evaporation residues in water bath

Abstract

The invention provides a method for rapidly measuring the content of emulsified asphalt evaporation residues in a water bath, which comprises the following steps: S1, pouring emulsified asphalt into a container, then pouring an ethanol water solution, and uniformly mixing; s2, the container is placed in a boiling water bath environment, heating is conducted while even mixing is conducted, and the test is finished when the mass change of emulsified asphalt evaporation residues and the beaker within one minute does not exceed 1%; s3, weighing the container, the emulsified asphalt and the mass of the emulsified asphalt evaporation residues and the container after the test is finished, and calculating the content of the emulsified asphalt evaporation residues; wherein the volume fraction of ethanol in the ethanol aqueous solution is 60%-85%. Compared with a traditional evaporation residue obtaining method, the method has the advantages that the test time can be effectively shortened, and the aging problem of the emulsified asphalt evaporation residues in the heating process is fully avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of road engineering materials, and particularly relates to a method for rapidly determining the content of evaporation residue of emulsified asphalt in a water bath. Background Art

[0002] Emulsified asphalt is a special asphalt material. It is a kind of asphalt emulsion in which viscous asphalt is dispersed in water containing emulsifier - stabilizer in the form of micro - droplets through heat melting and mechanical action, forming an oil - in - water (O / W) type. It has the characteristics of low viscosity and good fluidity at normal temperature and is widely used in the field of road construction, such as being used as a waterproof layer, bonding layer, permeable layer, etc., and can also be used as the main cementing material for technologies such as slurry seal, cold mix and cold lay mixture, cold recycled asphalt pavement, etc., playing an important role in modern road construction and maintenance.

[0003] In actual use, the viscosity and fluidity of emulsified asphalt should be maintained within a certain range. Too high viscosity will lead to a decrease in fluidity and affect permeability; too low viscosity will affect the adhesion between emulsified asphalt and aggregates or the base layer, reducing its stability and durability. And the viscosity of emulsified asphalt is closely related to its concentration (i.e., the content of evaporation residue of emulsified asphalt). To ensure that emulsified asphalt maintains an appropriate viscosity during actual use, relevant national technical specifications and standards clearly stipulate that in the production and use of emulsified asphalt, its solid content should be controlled between 55% and 62%. Therefore, accurately measuring the content of evaporation residue in emulsified asphalt is the key to verifying the production and finished product quality of emulsified asphalt.

[0004] Currently, "Test Regulations for Bitumen and Bituminous Mixtures for Highway Engineering" (JTG E20 - 2011) stipulates that the content of evaporation residue of emulsified asphalt is determined in the following way: The container containing the emulsified asphalt sample together with the glass rod is placed on an electric furnace or gas furnace (with an asbestos pad) and heated slowly, stirring while heating. The heating temperature should not cause the emulsion to overflow until it is confirmed that the water in the sample has completely evaporated, and then it is heated at a temperature of 163 ± 3.0 °C for 1 minute. Finally, after cooling, the total mass of the container, evaporation residue, and glass rod is weighed and then the mass of the container and glass rod is deducted to calculate the content of the evaporation residue. This method has the following drawbacks: (1) It requires manual stirring for a long time until the sample is completely evaporated, which has high requirements for the technical operation level of the operator; (2) It depends on subjective judgment to stop heating, and there is a problem that secondary heating is required when the water is not completely evaporated, affecting the accuracy and repeatability of the test results; (3) For the evaluation of the material properties of emulsified asphalt, conventional asphalt property tests (such as penetration, ductility, softening point, etc.) need to be carried out on the evaporation residue of emulsified asphalt. The traditional direct heating evaporation method may cause asphalt aging due to high - temperature heating, significantly affecting the rheological properties of the evaporation residue of emulsified asphalt and unable to accurately reflect the actual properties of emulsified asphalt materials. Summary of the Invention

[0005] In view of this, the present invention provides a method for rapidly determining the content of the evaporation residue of emulsified asphalt by water bath. By adding an ethanol aqueous solution to the emulsified asphalt, the surface tension and polarity of the emulsified asphalt are changed, and the oil-water interface film is destroyed, so that the asphalt particles rapidly aggregate and break emulsion to promote the separation of oil and water; at the same time, ethanol will form an azeotropic mixture with the water in the emulsified asphalt, reducing its boiling point, so that the water-ethanol mixture can be rapidly volatilized in a boiling water bath environment. Compared with the traditional method for obtaining the evaporation residue, this method can effectively shorten the test time and fully avoid the aging problem of the evaporation residue of emulsified asphalt during heating.

[0006] The technical solution of the present invention is realized as follows: In the first aspect, the present invention provides a method for rapidly determining the content of the evaporation residue of emulsified asphalt by water bath, including the following steps: S1. Pour the emulsified asphalt into a container, and then pour the ethanol aqueous solution and mix well; S2. Place the container in a boiling water bath environment, heat while mixing well, and the test ends when the mass change of the evaporation residue of the emulsified asphalt and the beaker within 1 minute does not exceed 1%; S3. Weigh the container, the emulsified asphalt, and the mass of the evaporation residue of the emulsified asphalt and the container after the test ends, and the content of the evaporation residue of the emulsified asphalt can be calculated. Wherein, the volume fraction of ethanol in the ethanol aqueous solution is 60% - 85%.

[0007] The addition of ethanol will reduce the surface tension of the emulsified asphalt, and at the same time change the polar environment of the emulsified asphalt, change the orientation arrangement of the emulsifier and destroy the interfacial film formed by the emulsifier at the oil-water interface, promote the polymerization and condensation of asphalt particles to cause demulsification and precipitation, realize the separation of oil and water, thereby reducing the restraint of water molecules by asphalt particles and emulsifiers during heating, and improving the evaporation rate of water in the emulsified asphalt.

[0008] The addition of ethanol can form an azeotropic mixture with the water in the emulsified asphalt. The boiling point of the formed ethanol-water azeotropic mixture is about 80 - 90 °C. Therefore, in a boiling water bath environment, the ethanol-water azeotropic mixture can be completely evaporated.

[0009] On the basis of the above technical solution, further, step S1 is to pour the emulsified asphalt into a container, pour the ethanol aqueous solution while mixing well, so that the emulsified asphalt and the ethanol aqueous solution are fully mixed.

[0010] On the basis of the above technical solution, further, the temperature of the boiling water bath environment is the boiling temperature of the water bath under standard atmospheric pressure.

[0011] On the basis of the above technical solutions, further, the evaporation residue content of the emulsified asphalt is calculated by the formula C = (m3 - m2) / m1 × 100%, where C is the evaporation residue content of the emulsified asphalt, m1 is the mass of the emulsified asphalt, m2 is the mass of the container, and m3 is the mass of the evaporation residue of the emulsified asphalt and the container after the test.

[0012] On the basis of the above technical solutions, further, the volume fraction of ethanol in the ethanol aqueous solution is 65% - 80%.

[0013] On the basis of the above technical solutions, further, the mass ratio of the ethanol aqueous solution to the emulsified asphalt is (20% - 40%) : 1.

[0014] On the basis of the above technical solutions, further, the mass ratio of the ethanol aqueous solution to the emulsified asphalt is (25% - 35%) : 1.

[0015] On the basis of the above technical solutions, further, the dosage of the emulsified asphalt is 300 g ± 1 g.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) By promoting the demulsification of the emulsified asphalt, the present invention reduces the restraint of water molecules by asphalt particles and emulsifiers during heating, and improves the evaporation rate of water in the emulsified asphalt; on the other hand, by forming an azeotropic mixture, the boiling point of the ethanol - water mixture is reduced, which can also enhance the evaporation rate of water, shorten the overall test time, and improve work efficiency.

[0017] (2) By forming an azeotropic mixture, the present invention reduces the boiling point of the ethanol - water mixture to 80 - 90 °C, enabling the evaporation residue of the emulsified asphalt to be obtained in a boiling water bath environment, and the temperature of the boiling water bath environment is only 100 °C. Compared with the traditional method using 163 °C, the aging effect of heating on the evaporation residue of the emulsified asphalt can be significantly reduced, ensuring that the performance of the evaporation residue of the emulsified asphalt is not affected.

[0018] (3) Compared with the traditional method of slowly heating the container containing the emulsified asphalt sample together with the glass rod on an electric furnace or gas furnace (with an asbestos pad), the heating method using a boiling water bath environment in the present invention can avoid the problem of local rapid heating. Through the "fully enclosed" boiling water bath heating method, the effect of uniform heating and increased heating points can be achieved, avoiding uneven heating while improving the heating and evaporation efficiency. Specific embodiments

[0019] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0020] In the following specific embodiments, the emulsified asphalt in each embodiment and the comparative example is 10 portions taken from the same emulsified asphalt sample after being fully stirred and evenly mixed, with each portion being 300 g.

[0021] The emulsified asphalt is purchased from Huayun Tongda Technology Group Co., Ltd., and the product number is PC-3.

[0022] Example 1 This example provides a method for quickly determining the evaporation residue content of emulsified asphalt in a water bath, including the following steps: Weigh 300 g of emulsified asphalt and pour it into a beaker. Then, while stirring, slowly pour 80 g of an ethanol aqueous solution (ethanol volume fraction is 65%) and mix well. Then, place the beaker in a boiling water bath environment (under standard atmospheric pressure, the boiling temperature of the water bath is 100 °C) and heat while stirring to completely evaporate the water and ethanol.

[0023] Calculate the evaporation residue content of the emulsified asphalt through the formula C = (m3 - m2) / m1 × 100%, where before pouring the emulsified asphalt into the beaker, weigh the masses m1 and m2 of the emulsified asphalt and the beaker respectively; the test ends when the mass change of the evaporation residue of the emulsified asphalt and the beaker does not exceed 1% within 1 minute. After the test, weigh the mass m3 of the evaporation residue of the emulsified asphalt and the beaker.

[0024] Example 2 This example provides a method for quickly determining the evaporation residue content of emulsified asphalt in a water bath. The difference from Example 1 is that the amount of the ethanol aqueous solution (ethanol volume fraction is 60%) is 60 g.

[0025] Example 3 This example provides a method for quickly determining the evaporation residue content of emulsified asphalt in a water bath. The difference from Example 1 is that the amount of the ethanol aqueous solution (ethanol volume fraction is 85%) is 120 g.

[0026] Example 4 This example provides a method for quickly determining the evaporation residue content of emulsified asphalt in a water bath. The difference from Example 1 is that the amount of the ethanol aqueous solution (ethanol volume fraction is 65%) is 75 g.

[0027] Example 5 This embodiment provides a method for quickly determining the content of the evaporation residue of emulsified asphalt in a water bath. The difference from Embodiment 1 is that the amount of the ethanol aqueous solution (ethanol volume fraction is 65%) is 105 g.

[0028] Embodiment 6 This embodiment provides a method for quickly determining the content of the evaporation residue of emulsified asphalt in a water bath. The difference from Embodiment 1 is that the amount of the ethanol aqueous solution (ethanol volume fraction is 80%) is 80 g.

[0029] Comparative Example 1 This comparative example provides a method for determining the content of the evaporation residue of emulsified asphalt as specified in the "Test Regulations for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20 - 2011), including the following steps: Weigh 300 g of emulsified asphalt, and perform the test operation using the method of the test for the content of the evaporation residue of emulsified asphalt (T 0651 - 1993) specified in the "Test Regulations for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20 - 2011).

[0030] Comparative Example 2 This comparative example provides a method for determining the evaporation residue of emulsified asphalt by "boiling water bath + short - time electric furnace heating", including the following steps: Weigh 300 g of emulsified asphalt and pour it into a beaker, then place the beaker in a boiling water bath environment (under standard atmospheric pressure, the boiling temperature of the water bath is 100 °C) and heat it while stirring to evaporate the water. To ensure complete evaporation of the water, finally place the beaker on an electric furnace (with an asbestos pad) and heat it slowly for 5 minutes, and then place it in an oven at 163 °C and let it stand for 1 minute according to the standard method.

[0031] Calculate the content of the evaporation residue of emulsified asphalt through the formula C = (m3 - m2) / m1×100%, where before pouring the emulsified asphalt into the beaker, weigh the masses m1 and m2 of the emulsified asphalt and the beaker respectively; the test ends when the mass change of the evaporation residue of emulsified asphalt and the beaker within 1 minute does not exceed 1%. After the test, weigh the mass m3 of the evaporation residue of emulsified asphalt and the beaker.

[0032] Comparative Example 3 The difference between this comparative example and Embodiment 1 is that anhydrous ethanol is used instead of the ethanol aqueous solution, and the amount of anhydrous ethanol is 80 g.

[0033] Comparative Example 4 The difference between this comparative example and Embodiment 1 is that the amount of the ethanol aqueous solution (ethanol volume fraction is 30%) is 80 g.

[0034] Performance Detection The heating and evaporation durations, the measured evaporation residue contents of the emulsified asphalt, and the test results of various properties of the evaporation residues of the emulsified asphalt in Examples 1 to 6 and Comparative Examples 1 to 4 are summarized in Table 1 as follows.

[0035] Table 1 Comparison of heating and evaporation durations, measured evaporation residue contents of emulsified asphalt, and properties of evaporation residues of emulsified asphalt for different test methods of evaporation residue contents of emulsified asphalt

[0036] As can be seen from Table 1, when using the method for rapidly determining the evaporation residue content of emulsified asphalt by water bath proposed in the present invention, the error between the measured evaporation residue content value of the emulsified asphalt and the method specified in the current "Test Procedures for Bitumen and Bituminous Mixtures for Highway Engineering" (JTG E20 - 2011) (Comparative Example 1) is within 0.4%, indicating that the method proposed in the present invention can accurately measure the evaporation residue content of emulsified asphalt. In addition, by comparing the heating and evaporation times, it can be found that the total time of Examples 1 - 6 is shortened by more than 10% compared with Comparative Example 1 (i.e., the standard method), and the total heating and evaporation time of Example 3 with a higher - concentration ethanol aqueous solution added is even shorter.

[0037] In addition, in order to verify the influence degree of the method proposed in the present invention on the properties of the evaporation residue of emulsified asphalt, Comparative Example 2 was specially set up. The method of "boiling water bath + short - time electric furnace heating" was used to obtain the evaporation residue of emulsified asphalt. The evaporation residue of emulsified asphalt obtained by this method can be considered to be little affected by heating and aging. By comparing the properties of the evaporation residues of emulsified asphalt obtained in Examples 1 - 6 and Comparative Example 2, it can be found that the penetration, softening point, and ductility of the evaporation residues of the 6 groups of emulsified asphalt are relatively close; in contrast, the penetration of the evaporation residue of emulsified asphalt obtained by Comparative Example 1 (i.e., the standard method) is smaller, the softening point is higher, and the ductility is lower, indicating that there is an aging phenomenon of the evaporation residue of emulsified asphalt when using the traditional slow heating method with an electric furnace or gas furnace; at the same time, it can also be concluded by comparison that the method for rapidly determining the evaporation residue content of emulsified asphalt by water bath proposed in the present invention can greatly reduce the aging influence of the heating process on asphalt materials and can more truly reflect the properties of the evaporation residue of emulsified asphalt.

[0038] When anhydrous ethanol was poured in Comparative Example 3, during the experiment, the asphaltenes in the emulsified asphalt precipitated too fast and agglomerated, and it was impossible to achieve heating while stirring well. Therefore, the test was stopped halfway and no relevant data was recorded. This also shows that: the higher the concentration of the ethanol aqueous solution added, the faster the evaporation efficiency of water. But at the same time, due to the increase in concentration, it may cause the emulsified asphalt to break and coagulate too fast to form agglomerates, which is not conducive to further stirring and evaporating water. Therefore, ethanol aqueous solutions with appropriate concentrations should be used according to different types of emulsified asphalt.

[0039] In Comparative Example 4, a certain amount of low-concentration ethanol aqueous solution was poured into the emulsified asphalt. Although the addition of ethanol had a certain effect of promoting the demulsification and precipitation of the emulsified asphalt, due to the low concentration, more water was added to the emulsified asphalt. Therefore, when the evaporation was carried out by the method of the present invention, the required evaporation time was longer. Therefore, the concentration of the ethanol aqueous solution should not be too low.

[0040] In summary, the method of the present invention can effectively shorten the test time and fully avoid the aging problem of the evaporation residue of the emulsified asphalt during the heating process.

[0041] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for rapidly determining the content of evaporation residue of emulsified asphalt by water bath, characterized in that, Including the following steps: S1. Pour the emulsified asphalt into a container, and then pour in the ethanol aqueous solution and mix evenly; S2. Place the container in a boiling water bath environment, heat while mixing evenly, and end the test when the mass change of the evaporation residue of the emulsified asphalt and the beaker within 1 minute does not exceed 1%; S3. Weigh the container, the emulsified asphalt, and the mass of the evaporation residue of the emulsified asphalt and the container after the test, and the content of the evaporation residue of the emulsified asphalt can be calculated; Among them, the volume fraction of ethanol in the ethanol aqueous solution is 60% - 85%.

2. The method for rapidly measuring the evaporation residue content of emulsified asphalt in a water bath according to claim 1, characterized in that, The volume fraction of ethanol in the ethanol aqueous solution is 65% - 80%.

3. The method for rapidly determining the content of evaporation residue of emulsified asphalt by water bath according to claim 1, characterized in that, The mass ratio of the ethanol aqueous solution to the emulsified asphalt is (20% - 40%):

1.

4. The method for rapidly measuring the content of the evaporation residue of emulsified asphalt in a water bath according to claim 1, wherein, The mass ratio of the ethanol aqueous solution to the emulsified asphalt is (25% - 35%):1.

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