Warm mix smoke suppression modified asphalt and preparation method thereof

Abstract

The present invention discloses a warm-mix smoke-suppressing modified asphalt and a preparation method thereof. The warm-mix smoke-suppressing modified asphalt is a composite material comprising asphalt and a warm-mix smoke suppressant, belonging to the technical field of functional pavement materials. The present invention is prepared from the following raw materials in parts by weight: 100 parts by weight of base asphalt, 2 to 6 parts by weight of sodium bentonite (NaB), 0.4 to 0.8 parts by weight of Evotherm warm-mix agent, and 2.5 to 5 parts by weight of magnesium hydroxide (MH) modified with an aluminate coupling agent. The three constitute a synergistic smoke suppression system that has the effect of lowering the mixing temperature of the asphalt mixture, effectively reducing the emission of asphalt smoke, and effectively improving the high-temperature performance and deformation resistance of the asphalt.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional pavement materials, and in particular relates to a warm-mix smoke-suppressing modified asphalt and a preparation method thereof. Background Art

[0002] The transportation industry is a key energy consumer and a significant source of atmospheric pollutant emissions. Asphalt pavement accounts for a significant portion of the road transportation industry. Asphalt pavement is typically constructed using hot-mix asphalt. The preparation temperature for hot-mix asphalt is between 140 and 180°C, which consumes significant energy and produces significant amounts of asphalt fumes. This pollutes the environment and poses a health risk to on-site construction workers. Therefore, research into hot-mix asphalt with smoke suppression is essential.

[0003] Warm mix smoke suppression modified asphalt is made by adding smoke suppressants and warm mix agents to base asphalt. The suppression effect of existing asphalt smoke suppressants is not obvious, and the added ingredients are too many, which makes the asphalt easy to segregate, the ductility index decreases significantly, and the preparation process is cumbersome.

[0004] For example, Chinese patent 201711095579.4 discloses a modified compound flame retardant, a high-efficiency warm-mix flame-retardant asphalt and a preparation method thereof. The flame-retardant asphalt includes a Sasobit-LM warm-mix agent, a zinc borate flame retardant, a magnesium hydroxide flame retardant, an ammonium polyphosphate smoke suppressant, a montmorillonite flame retardant synergist, a silane coupling agent or a titanate coupling agent. The warm-mix agent is added first and then the modified compound flame retardant. The stirring duration is about 2 hours at 150°C, which easily leads to asphalt aging problems. In addition, the Sasobit-LM warm-mix agent, silane coupling agent, and titanate used are expensive and relatively costly. Titanate is highly toxic and does not meet environmental protection requirements. The zinc borate smoke suppression effect is unstable. Ammonium polyphosphate has strong hygroscopicity and its chemical structure will change in high temperature and humid environments. The Sasobit warm-mix agent has a good cooling effect, but obvious cracking. The montmorillonite structure is a columnar structure with no water film between the crystal particles, weak adsorption, and poor flame retardant and smoke suppression effects. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a warm-mix smoke-suppressing modified asphalt and a preparation method thereof. The modified asphalt has the advantages of low smoke production, low cost, and few components. On the premise of meeting the smoke suppression rate requirements, other road performance indicators can meet the technical requirements and even far exceed the specification requirements.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A warm-mix smoke suppression modified asphalt, wherein the components in the warm-mix smoke suppression modified asphalt are calculated in parts by mass as follows:

[0008] 100 parts of base asphalt,

[0009] 2.5-5 parts of magnesium hydroxide (MH) modified with aluminate coupling agent,

[0010] Sodium bentonite (NaB) 2-6 parts,

[0011] 0.4-0.8 parts of Evotherm warm mix agent.

[0012] The components in the warm mix smoke suppression modified asphalt are calculated in parts by mass as follows:

[0013] 100 parts of base asphalt,

[0014] 2.5-5 parts of magnesium hydroxide (MH) modified with aluminate coupling agent,

[0015] 4-6 parts of sodium bentonite (NaB),

[0016] 0.4-0.8 parts of Evotherm warm mix agent.

[0017] Furthermore, the warm-mix smoke suppression modified asphalt has an ductility greater than 30 cm, a softening point of above 50° C., and an inhibition rate of above 32%.

[0018] Furthermore, the preparation process of the warm-mix smoke-suppressing modified asphalt is as follows: heating the base asphalt to change the asphalt from a solid state to a liquid state, then heating it while keeping the temperature low until it is molten, adding magnesium hydroxide modified with an aluminate coupling agent at a shear rate of 3000-3600 r / min, and mixing until no obvious white powder is left when dipped in with a glass rod, thereby obtaining a primary mixture;

[0019] Sodium bentonite and Evotherm warm mix agent are added to the primary mixture under heat preservation conditions, the shear rate is increased to 400-500r / min, and the mixture is sheared evenly until no obvious solid powder is left to obtain warm mix smoke suppression modified asphalt.

[0020] Furthermore, the sodium bentonite has a montmorillonite content of 60% to 88%, a particle size of 325 meshes, an expansion capacity of 25 to 50 ml / g, Na2O ≥ 1.28, and a colloid value ≥ 99 ml / 15g.

[0021] The viscosity of the Evotherm warm mix agent at 30°C is 360-630 mPa·s, and the pH value at 25°C is 10-12.

[0022] The density of magnesium hydroxide is 2.36 g / cm 3 , melting point is 350℃ and molar mass is 58.3g / mol.

[0023] It is further defined that the amount of the aluminate coupling agent added to modify the magnesium hydroxide is 1% by mass of the magnesium hydroxide.

[0024] The aluminate coupling agent is DL-411 aluminate coupling agent.

[0025] The specific preparation method of the above-mentioned warm mix smoke suppression modified asphalt includes the following steps:

[0026] (1) Preparation of magnesium hydroxide (MH) modified with aluminate coupling agent

[0027] The magnesium hydroxide powder was placed in an oven at 105°C and dried for 2 hours. The dried powder was added to an alcohol-water solution to prepare a slurry with a concentration of 40-50 g / ml. An aluminate coupling agent was slowly added dropwise and stirred for 30 minutes. The stirred slurry was placed in an oven at a constant temperature of 60°C and dried for 30 minutes. The slurry was taken out and crushed. The powder was extracted with a Soxhlet extractor for 8 hours. The extracted powder was dried and crushed again at 60°C.

[0028] (2) placing the matrix asphalt in a constant temperature oven and heating it until the matrix asphalt completely changes from solid to liquid, the heating temperature of the constant temperature oven is the melting point temperature of the matrix asphalt, and the heating time is 20-35 minutes; then, heat it on a closed electromagnetic oven until it is molten, the insulation temperature of the electromagnetic oven is 5-8°C higher than the melting point temperature of the matrix asphalt, the electromagnetic oven is located below the shearing machine, and the shearing machine is controlled to stir at a low speed (shear rate of 3000-3600 r / min) and magnesium hydroxide modified with aluminate coupling agent is added. Shear for 15 minutes, and a glass rod is used to dip in a mixture without obvious white powder to obtain a uniformly mixed primary mixture. Since a small amount of modified magnesium hydroxide is added, it does not need to be sheared for too long to be well compatible with the matrix asphalt;

[0029] (3) Add sodium bentonite and Evotherm warm mix agent to the primary mix under heat preservation, increase the shear rate to 400-500 r / min, and shear evenly until there is no obvious solid powder. Shear for 30-40 minutes to obtain warm mix smoke suppression modified asphalt. If the shearing time is too long, aging problems will occur, and the asphalt will easily become hard and hard, and the needle penetration will decrease. The above shearing time is controlled within an appropriate range to ensure that the asphalt is always in a viscous state and can be easily stirred without showing a watery state.

[0030] Furthermore, the heating temperature of the thermostat is 135°C, and the insulation temperature of the induction cooker is 140°C.

[0031] Furthermore, after the aluminate coupling agent is dripped into step (1), the shear rate is 500 r / min and the shear time is 30 min; the shear rate in step (2) is 3500 r / min and the shear time is 15 min; and the shear rate in step (3) is 4000 r / min and the shear time is 30 min.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The warm-mix smoke suppression modified asphalt of the present invention has a layered structure in which a large amount of water film is present between the stacked plates, which has strong adsorption and can fix asphalt smoke particles. In addition, the sodium bentonite is catalyzed into carbon to form a carbon layer on the asphalt surface, which can also prevent the release of smoke. Compared with other types of bentonite such as montmorillonite and calcium bentonite, the sodium bentonite has a stronger adsorption capacity. Since the type of bentonite is composed of interlayer cations Ca + 、Na + It is determined that the dispersibility of sodium bentonite is significantly better than that of calcium bentonite, and it is more suitable for addition to asphalt. After compounding with modified magnesium hydroxide, the modified magnesium hydroxide can promote the carbonization of sodium bentonite. The two have a synergistic effect. At the same time, the magnesium oxide produced by the decomposition of magnesium hydroxide has high strength and high heat resistance, isolating the asphalt from contact with air, reducing the oxidation of asphalt, and reducing the release of asphalt smoke. In addition, magnesium hydroxide has a strong neutralization ability with acid, which can quickly neutralize SO2 and NO released by asphalt. x , CO2 and other acidic gases, and suppress smoke through physical and chemical effects. Compared with aluminum hydroxide, magnesium hydroxide has higher decomposition ability and flame retardant and smoke suppression efficiency, and its cost is half of that of aluminum hydroxide. Finally, Evotherm warm mix agent is compounded to reduce the amount of smoke by lowering the mixing temperature, and the addition of Evotherm warm mix agent does not affect the three major indicators of asphalt road performance; the three work together to suppress smoke, so that the asphalt smoke suppression rate reaches more than 32%, or even more than 35.2%. The optimal smoke suppression rate is 32%-36%.

[0034] The present invention adopts the response surface methodology to establish a model, selects the modified MH content (A), NaB content (B), and Evotherm content (C) as observation factors, takes the penetration, softening point, ductility at 10°C, and smoke suppression rate of asphalt as response values, designs experiments, and determines that the optimal compound content of the three components is 5% modified MH, 4% NaB, and 0.6% Evotherm. At this content, the penetration of asphalt is reduced, the hardness is increased, and the deformation resistance is enhanced; the softening point is increased, and the high-temperature performance is improved; the compatibility of asphalt with the smoke suppressant is also good, and the smoke suppression rate is above 35%.

[0035] The present invention utilizes sodium bentonite and magnesium hydroxide modified with an aluminate coupling agent as smoke suppressants, which are then compounded with an Evotherm warm-mix agent to produce a warm-mix smoke-suppressant modified asphalt. Evotherm reduces smoke emissions by lowering the mixing temperature, thus avoiding the cracking problem associated with the addition of the Sasobit warm-mix agent. Test results using three major indicators and smoke suppression rates demonstrate that the warm-mix smoke-suppressant modified asphalt of the present invention, despite its low composition, exhibits excellent smoke suppression effectiveness, good compatibility between the smoke suppressant and asphalt, enhanced high-temperature performance, increased hardness, improved deformation resistance, and ductility that meets regulatory requirements.

[0036] The warm-mix smoke-suppressing asphalt of this invention uses magnesium hydroxide modified with an aluminate coupling agent, which is low-toxic, environmentally friendly, and easily dispersible. The modified magnesium hydroxide is then compounded with sodium bentonite as a smoke suppressant. During the preparation process, the asphalt temperature and shear mixing time are strictly controlled to prevent asphalt aging. Tests have shown that excessively high continuous heating temperatures and prolonged shearing times during asphalt preparation can significantly increase asphalt aging. The warm-mix agent dosage should be neither too high nor too low. Too little results in a suppression rate of only approximately 10%, while too much affects the asphalt's road performance.

[0037] The warm-mix smoke suppression asphalt of the present invention has an ductility of more than 30 cm, a softening point of more than 50° C., a needle penetration of more than 55 / 0.1 mm, and an inhibition rate of more than 32%, which can meet actual application requirements.

[0038] In the preparation method of the present invention, mixing is carried out under heating conditions 5-8°C higher than the melting point of the base asphalt, and magnesium hydroxide modified by an aluminate coupling agent is first added to ensure the flow and deformation ability of the base, the compatibility of the admixture with the asphalt is also good, and the smoke suppression effect is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a comparison chart of the oil smoke coverage of asphalt based on PTFE filter membrane in Example 1 and Example 3. The smoke suppression rate of warm-mix smoke suppression modified asphalt at the optimal dosage reaches 35.4%.

[0040] Figure 2 This is a comparison chart of the predicted and actual values ​​of needle penetration, softening point, ductility and smoke suppression rate. The closer the points are to the same straight line, the better.

[0041] Figure 3 This is the interaction diagram between various factors of needle penetration. The red dot in the figure is the optimal solution.

[0042] Figure 4 This is the interaction diagram between the various factors of the softening point. The red dot in the figure is the optimal solution.

[0043] Figure 5 This is the interaction diagram between various factors of extension. The red dot in the figure is the optimal solution.

[0044] Figure 6 This is an interaction diagram between various factors affecting the smoke suppression rate. The red dot in the figure is the optimal solution.

[0045] Figure 7 This is the SEM photo of Lunt 70# matrix asphalt.

[0046] Figure 8 This is the SEM photo of warm-mix smoke suppression modified asphalt. The microstructure has not changed much compared with the base asphalt. The three additives are evenly dispersed and have good compatibility. DETAILED DESCRIPTION

[0047] To clarify the objectives, technical solutions, and advantages of the present invention, a response surface methodology was used to establish a model. The modified MH content (A), NaB content (B), and Evotherm content (C) were selected as observation factors, and the asphalt penetration, softening point, ductility at 10°C, and smoke suppression rate were used as response values. The experimental factors and levels are shown in Table 1. The present invention is further described in detail below in conjunction with the examples. It should be understood that the specific examples described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0048] Table 1

[0049]

[0050] Example 1

[0051] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 0 parts, the mass fraction of sodium bentonite (NaB) is 0 parts, and the mass fraction of Evotherm warm-mix agent is 0 parts, wherein the asphalt selected is specifically Lunt 70# asphalt.

[0052] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0053] Example 2

[0054] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 2.5 parts, the mass fraction of sodium bentonite (NaB) is 6 parts, and the mass fraction of Evotherm warm-mix agent is 0.6 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0055] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0056] Example 3

[0057] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 5 parts, the mass fraction of sodium bentonite (NaB) is 4 parts, and the mass fraction of Evotherm warm-mix agent is 0.6 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0058] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0059] Example 4

[0060] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 5 parts, the mass fraction of sodium bentonite (NaB) is 6 parts, and the mass fraction of Evotherm warm-mix agent is 0.4 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0061] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0062] Example 5

[0063] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 2.5 parts, the mass fraction of sodium bentonite (NaB) is 2 parts, and the mass fraction of Evotherm warm-mix agent is 0.6 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0064] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0065] Example 6

[0066] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 7.5 parts, the mass fraction of sodium bentonite (NaB) is 4 parts, and the mass fraction of Evotherm warm-mix agent is 0.4 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0067] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0068] Example 7

[0069] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 5 parts, the mass fraction of sodium bentonite (NaB) is 4 parts, and the mass fraction of Evotherm warm-mix agent is 0.6 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0070] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0071] Example 8

[0072] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 5 parts, the mass fraction of sodium bentonite (NaB) is 4 parts, and the mass fraction of Evotherm warm-mix agent is 0.6 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0073] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0074] Example 9

[0075] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 5 parts, the mass fraction of sodium bentonite (NaB) is 4 parts, and the mass fraction of Evotherm warm-mix agent is 0.6 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0076] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0077] Example 10

[0078] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 5 parts, the mass fraction of sodium bentonite (NaB) is 2 parts, and the mass fraction of Evotherm warm-mix agent is 0.8 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0079] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0080] Example 11

[0081] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 5 parts, the mass fraction of sodium bentonite (NaB) is 4 parts, and the mass fraction of Evotherm warm-mix agent is 0.6 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0082] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0083] Example 12

[0084] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 7 parts, the mass fraction of sodium bentonite (NaB) is 4 parts, and the mass fraction of Evotherm warm-mix agent is 0.8 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0085] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0086] Example 13

[0087] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 7.5 parts, the mass fraction of sodium bentonite (NaB) is 6 parts, and the mass fraction of Evotherm warm-mix agent is 0.6 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0088] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0089] Example 14

[0090] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 7.5 parts, the mass fraction of sodium bentonite (NaB) is 2 parts, and the mass fraction of Evotherm warm-mix agent is 0.6 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0091] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0092] Example 15

[0093] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 5 parts, the mass fraction of sodium bentonite (NaB) is 6 parts, and the mass fraction of Evotherm warm-mix agent is 0.8 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0094] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0095] Example 16

[0096] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 5 parts, the mass fraction of sodium bentonite (NaB) is 2 parts, and the mass fraction of Evotherm warm-mix agent is 0.4 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0097] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0098] Example 17

[0099] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 2.5 parts, the mass fraction of sodium bentonite (NaB) is 4 parts, and the mass fraction of Evotherm warm-mix agent is 0.4 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0100] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0101] Example 18

[0102] In the warm-mix smoke suppression modified asphalt of this embodiment, the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 2.5 parts, the mass fraction of sodium bentonite (NaB) is 4 parts, and the mass fraction of Evotherm warm-mix agent is 0.8 parts, among which the asphalt selected is specifically Lunt 70# asphalt.

[0103] The penetration, softening point, ductility and asphalt smoke suppression rate of asphalt were tested according to the basic performance test method of asphalt. The results are shown in Table 2.

[0104] Table 2

[0105]

[0106] The calculation formula of the inhibition rate in Table 2 is:

[0107]

[0108] The model was established based on the data in Table 2, and the variance analysis table of the regression model was obtained in Table 3.

[0109] Table 3

[0110]

[0111] As shown in Table 3, in the model variance analysis, the lack of fit error (P) is not significant, indicating that the model meets the requirements; R 2 Expressing the correlation between actual values ​​and predicted values, the values ​​of all four models are greater than 0.9, indicating that the change in response value is affected by the selected variables, and the predicted value has a high correlation with the actual value; CV / % represents the accuracy of the mathematical model, the smaller the value, the higher the accuracy, and the CV / % values ​​of the four models are all within the specified range.

[0112] In accordance with the objectives of this experiment, a multi-response surface optimization process was carried out: the lower the amount of smoke suppressant, the better, and the lower the amount, the more economical it is, so the amount of smoke suppressant was minimized; the larger the softening point of asphalt, the stronger its high-temperature stability, so the larger the softening point, the better while meeting the minimum requirements of the specification, so the softening point index was maximized; the greater the ductility of asphalt, the stronger its low-temperature cracking resistance, so the larger the ductility, the better while meeting the minimum requirements of the specification, so the ductility was maximized; the higher the smoke suppression rate, the better the smoke suppression performance of the composite dosage combination, so the smoke suppression rate was maximized, see Table 4 for details.

[0113] Table 4

[0114] name Target Lower limit Upper limit A: Modified MH minimize 2.5 7.5 B:NaB minimize 2 6 C:Evotherm minimize 0.4 0.8 Needle penetration minimize 56.8 63.2 Softening point maximize 56.9 58.9 Elongation maximize 26.3 36.2 Smoking suppression rate maximize 31.8 35.8

[0115] The response surface methodology was used to determine the optimal mass fractions of the three additives, which were 5 parts modified MH, 4 parts NaB, and 0.6 parts Evotherm. The actual results at these dosages are shown in Table 5.

[0116] Table 5

[0117] index predict actual Needle penetration / 0.1mm 59.4 61.5 Softening point / ℃ 57.7 57.0 Elongation / cm 32.2 34.9 Smoke suppression rate / % 34.2 35.4

[0118] As shown in Table 5, the predicted values ​​are very close to the experimental values, and the model fit is high.

[0119] From the above data, it can be seen that Examples 3, 7, 8, 9, 10, and 11 can be considered as parallel experiments of response surface simulation, and the smoke suppression rates are all above 35%.

[0120] The following is a comparative example of unmodified magnesium hydroxide, modified aluminum hydroxide, calcium-based bentonite and Sasobit warm mix agent based on Example 11 of the optimal blending combination.

[0121] Comparative Example 1

[0122] Comparative Example 11 is a warm-mix smoke suppression modified asphalt, wherein the mass fraction of base asphalt is 100 parts, the mass fraction of unmodified magnesium hydroxide (MH) is 5 parts, the mass fraction of sodium bentonite (NaB) is 4 parts, and the mass fraction of Evotherm warm-mix agent is 0.6 parts, wherein the asphalt selected is specifically Lunt 70# asphalt.

[0123] According to the basic performance test method of asphalt, its penetration, softening point, ductility and asphalt smoke suppression rate were tested. The results are shown in Table 6.

[0124] Table 6

[0125]

[0126] It can be seen from Table 6 that after unmodified magnesium hydroxide (MH) is compounded with sodium bentonite (NaB) and Evotherm warm mix agent, the ductility of asphalt decreases significantly and the smoke suppression rate is low.

[0127] Comparative Example 2

[0128] Comparative Example 11 is a warm-mix smoke suppression modified asphalt, in which the mass fraction of base asphalt is 100 parts, the mass fraction of modified aluminum hydroxide is 5 parts, the mass fraction of sodium bentonite (NaB) is 4 parts, and the mass fraction of Evotherm warm-mix agent is 0.6 parts, wherein the asphalt selected is specifically Lunt 70# asphalt.

[0129] According to the basic performance test method of asphalt, its penetration, softening point, ductility and asphalt smoke suppression rate were tested. The results are shown in Table 7.

[0130] Table 7

[0131]

[0132] It can be seen from Table 7 that after the modified aluminum hydroxide is compounded with sodium bentonite (NaB) and Evotherm warm mix agent, compared with the present invention, the warm mix smoke suppression asphalt of the present invention has a lower needle penetration, better asphalt deformation resistance, higher softening point, stronger high-temperature rutting resistance, little difference in ductility, and better smoke suppression effect.

[0133] Comparative Example 3

[0134] Comparative Example 11 is a warm-mix smoke suppression modified asphalt, wherein the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 5 parts, the mass fraction of calcium-based bentonite (NaB) is 4 parts, and the mass fraction of Evotherm warm-mix agent is 0.6 parts, wherein the asphalt selected is specifically Lunt 70# asphalt.

[0135] According to the basic performance test method of asphalt, its penetration, softening point, ductility and asphalt smoke suppression rate were tested. The results are shown in Table 8.

[0136] Table 8

[0137]

[0138] It can be seen from Table 8 that after modified magnesium hydroxide (MH) is compounded with calcium-based bentonite and Evotherm warm mix agent, compared with the present invention, the warm mix smoke suppression asphalt of the present invention has a higher softening point, stronger high-temperature deformation resistance, higher ductility, better low-temperature crack resistance, and better smoke suppression effect.

[0139] Because Sasobit warm-mix agent offers superior warm-mix performance, it was compared with Evotherm warm-mix agent. Experimental research has shown that the optimal addition level for Sasobit warm-mix agent alone is 3%. At this level, all three warm-mix asphalt performance indicators meet regulatory requirements. Further increases in the addition level significantly reduce ductility and lead to more severe pavement cracking. Therefore, Sasobit warm-mix agent was compounded into smoke-suppressing asphalt at three different weight ratios: 2, 3, and 4 parts by weight.

[0140] Comparative Example 4

[0141] Comparative Example 11 is a warm-mix smoke suppression modified asphalt, wherein the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 5 parts, the mass fraction of sodium bentonite (NaB) is 4 parts, and the mass fraction of Sasobit warm-mix agent is 2 parts, wherein the asphalt selected is specifically Lunt 70# asphalt.

[0142] According to the basic performance test method of asphalt, its penetration, softening point, ductility and asphalt smoke suppression rate were tested. The results are shown in Table 9.

[0143] Comparative Example 5

[0144] Comparative Example 11 is a warm-mix smoke suppression modified asphalt, wherein the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 5 parts, the mass fraction of sodium bentonite (NaB) is 4 parts, and the mass fraction of Sasobit warm-mix agent is 3 parts, wherein the asphalt selected is specifically Lunt 70# asphalt.

[0145] According to the basic performance test method of asphalt, its penetration, softening point, ductility and asphalt smoke suppression rate were tested. The results are shown in Table 9.

[0146] Comparative Example 6

[0147] Comparative Example 11 is a warm-mix smoke suppression modified asphalt, wherein the mass fraction of base asphalt is 100 parts, the mass fraction of modified magnesium hydroxide (MH) is 5 parts, the mass fraction of sodium bentonite (NaB) is 4 parts, and the mass fraction of Sasobit warm-mix agent is 4 parts, wherein the asphalt selected is specifically Lunt 70# asphalt.

[0148] According to the basic performance test method of asphalt, its penetration, softening point, ductility and asphalt smoke suppression rate were tested. The results are shown in Table 9.

[0149] Table 9

[0150]

[0151] It can be seen from Table 9 that under the optimal blending combination, Evotherm warm mix agent is replaced by Sasobit. When the mass fraction of Sasobit is 2 parts, the three major indicators meet the specification requirements, but with respect to actual engineering applications, its elongation of 22.5 cm cannot meet the actual engineering needs, and the smoke suppression rate is lower than that of Example 11; when the mass fraction of Sasobit is 3 parts, the elongation of the smoke suppression asphalt is less than 20 cm, which no longer meets the specification requirements, and the smoke suppression rate is lower than that of Example 11; when the mass fraction of Sasobit is 4 parts, although the smoke suppression rate is increased compared with Example 11, the elongation index no longer meets the specification requirements, and the Sasobit content is relatively large, the price is relatively high, and the economy is poor.

[0152] The above are only 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 principles of the present invention should be included in the scope of protection of the present invention.

[0153] Any matters not described in the present invention are applicable to the prior art.

Claims

1. A warm mix smoke suppression modified asphalt, characterized in that: The components in the warm mix smoke suppression modified asphalt are calculated in parts by mass as follows: 100 parts of base asphalt, 2.5-5 parts of magnesium hydroxide modified with aluminate coupling agent, 2 to 6 parts of sodium bentonite, 0.4-0.8 parts of Evotherm warm mix agent.

2. The warm mix smoke suppression modified asphalt according to claim 1, characterized in that: The components in the warm mix smoke suppression modified asphalt are calculated in parts by mass as follows: 100 parts of base asphalt, 2.5-5 parts of magnesium hydroxide modified with aluminate coupling agent, 4-6 parts of sodium bentonite, 0.4-0.8 parts of Evotherm warm mix agent.

3. The warm mix smoke suppression modified asphalt according to claim 2, characterized in that: The warm-mix smoke suppression modified asphalt has an ductility of more than 30 cm, a softening point of more than 50° C., an inhibition rate of more than 32%, and a smoke suppression rate of 32%-36%.

4. The warm mix smoke suppression modified asphalt according to claim 3, characterized in that: The smoking suppression rate is 32%-36%.

5. The warm mix smoke suppression modified asphalt according to claim 1, characterized in that: The preparation process of the warm-mix smoke-suppressing modified asphalt is as follows: heating the base asphalt to change it from a solid state to a liquid state, then heating it to a molten state by heat preservation, adding magnesium hydroxide modified with an aluminate coupling agent at a shear rate of 3000-3600 r / min, and mixing until no obvious white powder is left when dipped in a glass rod, thereby obtaining a primary mixture; Sodium bentonite and Evotherm warm mix agent are added to the primary mixture under heat preservation conditions, the shear rate is increased to 400-500r / min, and the mixture is sheared evenly until no obvious solid powder is left to obtain warm mix smoke suppression modified asphalt.

6. The warm mix smoke suppression modified asphalt according to claim 1, characterized in that: The sodium bentonite has a montmorillonite content of 60% to 88%, a particle size of 325 meshes, an expansion capacity of 25 to 50 ml / g, Na2O ≥ 1.28, and a colloidal value ≥ 99 ml / 15g; The viscosity of the Evotherm warm mix agent at 30°C is 360-630 mPa·s, and the pH value at 25°C is 10-12; the density of the magnesium hydroxide is 2.36 g / cm 3 , a melting point of 350°C, and a molar mass of 58.3g / mol; the aluminate coupling agent is DL-411 aluminate coupling agent.

7. The warm mix smoke suppression modified asphalt according to claim 1, characterized in that: The amount of the aluminate coupling agent used to modify the magnesium hydroxide is 1% by mass of the magnesium hydroxide.

8. A method for preparing the warm-mix smoke-suppressing modified asphalt according to any one of claims 1 to 7, comprising the following steps: (1) Preparation of magnesium hydroxide modified with aluminate coupling agent The magnesium hydroxide powder was placed in an oven at 105°C and dried for 2 hours. The dried powder was added to an alcohol-water solution to prepare a slurry with a concentration of 40-50 g / ml. An aluminate coupling agent was slowly added dropwise and stirred for 30 minutes. The stirred slurry was placed in an oven at a constant temperature of 60°C and dried for 30 minutes. The slurry was taken out and crushed. The powder was extracted with a Soxhlet extractor for 8 hours. The extracted powder was dried and crushed again at 60°C. (2) placing the matrix asphalt in a constant temperature oven and heating it until the matrix asphalt completely changes from solid to liquid, wherein the heating temperature of the constant temperature oven is the melting point of the matrix asphalt, and the heating time is 20-35 minutes; then, heating it on a closed electromagnetic oven until it is molten, wherein the insulation temperature of the electromagnetic oven is 5-8°C higher than the melting point of the matrix asphalt, and the electromagnetic oven is located below the shearing machine, and the shearing machine is controlled to stir at a low speed, and magnesium hydroxide modified with an aluminate coupling agent is added, and a glass rod is used to dip in a glass rod without obvious white powder to obtain a uniformly mixed primary mixture; (3) Add sodium bentonite and Evotherm warm mix agent to the primary mixture under heat preservation, increase the shear rate to 400-500 r / min, and shear evenly until there is no obvious solid powder. Shear for 30-40 minutes to obtain warm mix smoke suppression modified asphalt.

9. The preparation method according to claim 8, characterized in that The heating temperature of the constant temperature oven is 135° C., and the insulation temperature of the induction cooker is 140° C.; after the aluminate coupling agent is dripped into the step (1), the shear rate is 500 r / min and the shear time is 30 min; the shear rate in the step (2) is 3000-3600 r / min and the shear time is 15 min; and the shear rate in the step (3) is 4000 r / min and the shear time is 30 min.

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