Warm mix flame retardant asphalt and preparation method thereof

Abstract

The present application relates to the field of asphalt mixtures, and specifically discloses a warm-mix flame-retardant asphalt and a preparation method thereof. A warm-mix flame-retardant asphalt comprises the following raw materials in parts by weight: 70-90 parts of asphalt, 1-3 parts of flame retardant, 0.5-1 parts of warm-mix agent, and 0.3-0.8 parts of triethyl acetyl citrate. A warm-mix flame-retardant asphalt of the present application is compounded with a warm-mix agent and a flame retardant. On the premise of ensuring the flame-retardant effect of the asphalt system, the temperature and viscosity of the asphalt mixture during mixing are also reduced, and the generation of asphalt smoke is reduced. At the same time, triethyl acetyl citrate is combined with a warm-mix agent, and triethyl acetyl citrate can reduce the viscosity of the asphalt system at high temperature, and can also improve the ductility of the prepared warm-mix flame-retardant asphalt at low temperature, so that the prepared asphalt has certain resilience and toughness at low temperature.

Description

Technical Field

[0001] The present application relates to the field of asphalt mixtures, and in particular to a warm mix flame retardant asphalt and a preparation method thereof. Background Art

[0002] Asphalt concrete pavement materials have the advantages of comfortable driving, low noise, and good anti-skid performance. However, asphalt road pavement is flammable, especially in asphalt road tunnels. Asphalt road tunnels are relatively closed and poorly ventilated, posing a potential fire hazard.

[0003] In the existing conventional process, flame retardants are added to asphalt to reduce the burning of asphalt and limit the occurrence of fire. However, after the flame retardant is added to asphalt, the hardness and viscosity of the asphalt mixture will increase, which will easily increase the mixing and paving temperature of the asphalt mixture, thus causing the asphalt mixture to easily generate asphalt smoke, which will cause harm to construction workers and the surrounding environment. Summary of the invention

[0004] In order to reduce the generation of asphalt smoke and lower the viscosity and temperature of asphalt mixing, the present application provides a warm-mix flame-retardant asphalt and a preparation method thereof.

[0005] In the first aspect, the present application provides a warm mix flame retardant asphalt, which adopts the following technical solution:

[0006] A warm-mix flame-retardant asphalt comprises the following raw materials in parts by weight: 70-90 parts of asphalt, 1-3 parts of flame retardant, 0.5-1 parts of warm-mix agent and 0.3-0.8 parts of triethyl acetyl citrate.

[0007] By adopting the above technical solution, a warm mix agent is added to the asphalt system, which can improve the construction and workability of the asphalt mixture, reduce the viscosity and heat of the asphalt during mixing, thereby reducing the temperature of the asphalt and the generation of asphalt smoke. Acetyl triethyl citrate is added to the asphalt system to weaken the van der Waals force between molecules by increasing the molecular gap, so that the molecular chains in the asphalt system are easy to move, which can reduce the viscosity and hardness of the asphalt mixture and improve the ductility and toughness of the asphalt. At the same time, acetyl triethyl citrate can also reduce the degree of crystallization of the asphalt mixture at low temperatures, reduce the phenomenon of asphalt becoming brittle and hardening in low temperature environments, improve the resilience and plastic deformation capacity of warm mix flame retardant asphalt, and improve the low temperature performance of warm mix flame retardant asphalt.

[0008] Preferably, the flame retardant is at least one of magnesium aluminum hydroxide, zinc borate and diatomaceous earth.

[0009] By adopting the above technical solution, when the temperature rises, magnesium aluminum hydroxide can absorb heat, decompose to release water and form an oxide film, thereby playing a flame retardant effect in the asphalt system, and magnesium aluminum hydroxide can also react with acidic substances in asphalt smoke to further reduce the release of asphalt smoke. At high temperatures above 300°C, zinc borate can absorb heat and release crystal water, playing the role of heat absorption, cooling and diluting oxygen in the asphalt system, and at the same time forming a protective film on the asphalt pavement to inhibit the generation of flammable gases, thereby playing a flame retardant effect in the asphalt system.

[0010] Diatomaceous earth has a large specific surface area and good fireproof and heat-insulating properties. It can be adsorbed on the surface of asphalt, reduce the heat on the surface of asphalt, and inhibit the generation of combustible gases, thereby achieving a flame retardant effect.

[0011] Preferably, the asphalt raw material also includes 0.3-0.5 parts of titanate coupling agent.

[0012] By adopting the above technical solution, the titanate coupling agent can modify the surface of the flame retardant, improve the compatibility between the flame retardant and asphalt, and improve the workability of the asphalt mixture, thereby further improving the flame retardant effect and smoke suppression effect of the asphalt system.

[0013] Preferably, the asphalt raw material also includes 1-3 parts of sodium stearate.

[0014] By adopting the above technical solution, sodium stearate can coat, disperse and lubricate magnesium aluminum hydroxide, zinc borate and diatomaceous earth in the flame retardant, reduce the surface energy of the flame retardant, make the flame retardant more compatible with asphalt, and improve the workability of asphalt mixture. At the same time, sodium stearate is adsorbed on the surface of the flame retardant and produces a certain steric hindrance on the surface of the flame retardant, reducing the phenomenon of flame retardant particle agglomeration, further reducing the viscosity of the asphalt system, and reducing the mixing temperature of the asphalt mixture.

[0015] Preferably, the diatomaceous earth particle size is 300-400 mesh, and the zinc borate particle size is 30-60 nm.

[0016] By adopting the above technical solution, the particle sizes of diatomaceous earth and zinc borate are controlled within an appropriate range. Under the premise of maintaining a good flame retardant effect, diatomaceous earth and zinc borate with smaller particle sizes can be better compatible with asphalt, thereby improving the workability of asphalt mixture.

[0017] Preferably, the warm mix agent comprises the following raw materials in parts by weight: 5-8 parts of alkylamine cationic surfactant, 3-5 parts of quaternary ammonium salt amphoteric surfactant, and 1-3 parts of carboxymethyl cellulose.

[0018] By adopting the above technical solution, the compounding of two surfactants, alkylamine cationic surfactant and quaternary ammonium salt amphoteric surfactant, has the effects of reducing viscosity, lubrication and foaming in the asphalt system, reducing the asphalt mixing temperature and reducing the generation of asphalt smoke. Carboxymethyl cellulose is added to the asphalt system to reduce the viscosity of the asphalt mixture when it is mixed, and at the same time, it can increase the viscosity of the asphalt mixture when the asphalt mixture is stationary and stored, effectively preventing the sinking, stratification and precipitation of asphalt particles, and improving the storage stability of the asphalt mixture.

[0019] In the second aspect, the present application provides a method for preparing warm mix flame retardant asphalt, adopting the following technical scheme: a method for preparing warm mix flame retardant asphalt, comprising the following specific steps: heating the asphalt, then adding a warm mix agent, a flame retardant and triethyl acetyl citrate to mix, thereby obtaining warm mix flame retardant asphalt.

[0020] Preferably, the asphalt heating temperature is 100-130°C.

[0021] By adopting the above technical scheme, the prepared warm-mix flame-retardant asphalt has excellent flame-retardant effect. Under the synergistic effect of various components, the workability of the asphalt system is improved, the asphalt mixing temperature and viscosity are reduced, and the generation of asphalt smoke is reduced.

[0022] In summary, this application has the following beneficial effects:

[0023] 1. Since the application adopts a compound of warm mix agent and flame retardant, the workability of the asphalt system is improved, the asphalt mixing temperature is reduced, and the generation of asphalt smoke is reduced. At the same time, triethyl acetyl citrate is used to reduce the low temperature hardness and high temperature viscosity of the asphalt system, so that the prepared warm mix flame retardant asphalt has good resilience and toughness.

[0024] 2. In this application, sodium stearate and titanate coupling agent are preferably used to modify the surface of the flame retardant. The titanate coupling agent can promote the flame retardant to be mixed with asphalt, improve the compatibility of the asphalt system, and reduce the viscosity and mixing temperature of the asphalt mixture. Sodium stearate can wrap the surface of the flame retardant, promote the flame retardant to be evenly dispersed in the asphalt system, reduce the agglomeration phenomenon between the flame retardant particles, further improve the workability of the asphalt mixture, and reduce the generation of asphalt smoke. DETAILED DESCRIPTION

[0025] The present application is further described in detail below with reference to the embodiments.

[0026] The average particle size of aluminum hydroxide is 40 μm.

[0027] The average particle size of magnesium hydroxide was 0.4 μm.

[0028] Preparation example of warm mix agent

[0029] Preparation Example 1

[0030] The warm mix agent comprises the following raw materials in parts by weight: 7 kg of alkylamine cationic surfactant, 4 kg of quaternary ammonium salt amphoteric surfactant, and 2 kg of carboxymethyl cellulose, wherein the alkylamine cationic surfactant is hexadecyl propylene diamine, and the quaternary ammonium salt amphoteric surfactant is dodecyl sulfobetaine.

[0031] The preparation method of the warm mix agent comprises the following specific steps: mixing an alkylamine cationic surfactant, a quaternary ammonium salt amphoteric surfactant, carboxymethyl cellulose and water, wherein the mass ratio of water to the alkylamine cationic surfactant is 6:1. Thus, the warm mix agent is obtained.

[0032] Preparation Example 2

[0033] The difference between Preparation Example 2 and Preparation Example 1 is that the amount of alkylamine cationic surfactant used in the warm mix agent raw material is 5 kg, the amount of quaternary ammonium salt amphoteric surfactant used is 5 kg, and the amount of carboxymethyl cellulose used is 1 kg.

[0034] Preparation Example 3

[0035] The difference between Preparation Example 3 and Preparation Example 1 is that the amount of alkylamine cationic surfactant used in the warm mix agent raw material is 8 kg, the amount of quaternary ammonium salt amphoteric surfactant used is 3 kg, and the amount of carboxymethyl cellulose used is 3 kg.

[0036] Preparation Example 4

[0037] The difference between Preparation Example 4 and Preparation Example 1 is that carboxymethyl cellulose is not used in the warm mix agent raw material.

[0038] Example

[0039] Example 1

[0040] This embodiment provides a warm mix flame retardant asphalt, including the following raw materials by weight: 80 kg of asphalt, 2 kg of flame retardant, 0.8 kg of warm mix agent, and 0.5 kg of triethyl acetyl citrate. The flame retardant is a mixture of aluminum hydroxide, zinc borate, and diatomaceous earth in a mass ratio of 1:1:1, the average particle size of zinc borate is 30 nm, the average particle size of diatomaceous earth is 300 mesh, and the warm mix agent is purchased from Evotherm M1, a warm mix agent provided by MeadWestvaco Corporation of the United States.

[0041] The preparation method of warm-mix flame-retardant asphalt includes the following specific steps: heating the asphalt to 120°C, then adding a warm-mix agent and triethyl acetyl citrate to mix, stirring at a speed of 800 r / min for 30 minutes, adding a flame retardant, and continuing to stir for 20 minutes to obtain the warm-mix flame-retardant asphalt.

[0042] Example 2-3

[0043] The difference between Example 2-3 and Example 1 is that the contents of the components in the warm mix flame retardant asphalt raw materials are different, as shown in Table 1 for details.

[0044] Table 1: Content of each component in Examples 1-3

[0045]

[0046] Example 4

[0047] The difference between Example 4 and Example 1 is that the flame retardant in the warm mix flame retardant asphalt raw material is a mixture of magnesium hydroxide and zinc borate in a mass ratio of 1:1.

[0048] Example 5

[0049] The difference between Example 5 and Example 1 is that the flame retardant in the warm mix flame retardant asphalt raw material is a mixture of diatomaceous earth and zinc borate in a mass ratio of 1:1, the average particle size of the zinc borate is 60 nm, and the average particle size of the diatomaceous earth is 400 mesh.

[0050] Example 6

[0051] The difference between Example 6 and Example 1 is that the warm mix agent in the warm mix flame retardant asphalt raw material comes from Preparation Example 1.

[0052] Example 7

[0053] The difference between Example 7 and Example 1 is that the warm mix agent in the warm mix flame retardant asphalt raw material comes from Preparation Example 2.

[0054] Example 8

[0055] The difference between Example 8 and Example 1 is that the warm mix agent in the warm mix flame retardant asphalt raw material comes from Preparation Example 3.

[0056] Example 9

[0057] The difference between Example 9 and Example 1 is that the warm mix agent in the warm mix flame retardant asphalt raw material comes from Preparation Example 4.

[0058] Example 10

[0059] The difference between Example 10 and Example 6 is that the warm mix flame retardant asphalt raw material also includes 0.4 kg of titanate coupling agent.

[0060] The preparation method of warm mix flame retardant asphalt comprises the following specific steps:

[0061] The flame retardant is dried at 100° C. in advance, and then the flame retardant and the titanate coupling agent are mixed and stirred evenly to obtain a modified flame retardant;

[0062] Then, after the asphalt is heated to 120°C, warm mix agent and triethyl acetyl citrate are added and mixed, and after stirring at a speed of 800r / min for 30 minutes, the modified flame retardant is added and stirring is continued for 20 minutes to obtain warm mix flame retardant asphalt.

[0063] Embodiment 11

[0064] The difference between Example 11 and Example 10 is that the amount of titanate coupling agent used in the warm mix flame retardant asphalt raw material is 0.3 kg.

[0065] Example 12

[0066] The difference between Example 12 and Example 10 is that the amount of titanate coupling agent used in the warm mix flame retardant asphalt raw material is 0.5 kg.

[0067] Embodiment 13

[0068] The difference between Example 13 and Example 10 is that the warm mix flame retardant asphalt raw material also includes 2 kg of sodium stearate.

[0069] The preparation method of warm mix flame retardant asphalt comprises the following specific steps:

[0070] The flame retardant is dried at 100° C. in advance, and then the flame retardant and the titanate coupling agent are mixed and stirred evenly to obtain a modified flame retardant;

[0071] Then heat the asphalt to 120°C, add warm mix agent and acetyl citrate triethyl, stir at 800r / min for 30min, add modified flame retardant and sodium stearate, continue stirring for 30min, and obtain warm mix flame retardant asphalt.

[0072] Embodiment 14

[0073] The difference between Example 14 and Example 13 is that the amount of sodium stearate used in the warm mix flame retardant asphalt raw material is 1 kg.

[0074] Embodiment 15

[0075] The difference between Example 15 and Example 13 is that the amount of sodium stearate used in the warm mix flame retardant asphalt raw material is 3 kg.

[0076] Comparative Example

[0077] Comparative Example 1

[0078] The difference between Comparative Example 1 and Example 1 is that acetyl triethyl citrate is not used in the warm mix flame retardant asphalt.

[0079] Comparative Example 2

[0080] The difference between Comparative Example 2 and Example 1 is that no warm mix agent and acetyl triethyl citrate are used in the warm mix flame retardant asphalt.

[0081] The preparation method of warm-mix flame-retardant asphalt comprises the following specific steps: heating the asphalt to 170° C., adding a flame retardant and stirring evenly to obtain the warm-mix flame-retardant asphalt.

[0082] Performance testing

[0083] The following performance tests were conducted on the warm mix flame retardant asphalt provided in Examples 1-15 and Comparative Examples 1-2 of the present application. The specific test results are shown in Table 2.

[0084] Detection Methods

[0085] 1. Smoke suppression performance

[0086] The smoke density of warm mix flame retardant asphalt is tested with reference to the standard of GB / 8627-2007 "Test for Flammability of Building Materials".

[0087] 2. Flame retardant properties

[0088] The oxygen index of the warm mix flame retardant asphalt prepared in this application was tested with reference to the standard of NB / SH / T0815-2010 "Oxygen Index Method for Determination of Combustion Performance of Asphalt".

[0089] 3. Extension

[0090] With reference to the standard of T0605-1993 "Asphalt Ductility Test", the 5°C ductility of the warm mix flame retardant asphalt prepared in this application was tested.

[0091] 4. Viscosity

[0092] The viscosity of the warm mix flame retardant asphalt of the present application at 80°C and 135°C was tested by using a NDJ-1C Brookfield rotational viscometer and referring to the standard JTGE20-2011 "Test Procedures for Asphalt and Asphalt Mixtures for Highway Engineering".

[0093] Table 2: Performance test data table

[0094]

[0095]

[0096] It can be seen from the performance test results that the warm-mix flame-retardant asphalt prepared in Examples 1-5 of the present application has a lower mixing temperature while maintaining a good flame-retardant effect under the synergistic effect of each component. The viscosity of the asphalt at high temperature is reduced by the warm-mix agent, thereby reducing the generation of asphalt smoke. In Examples 1-5 of the present application, triethyl acetyl citrate is used in combination with the warm-mix agent to promote the prepared warm-mix flame-retardant asphalt to have good ductility and viscosity at low temperatures, thereby reducing the phenomenon that the asphalt easily becomes brittle and hardens at low temperatures. In Examples 1-5 of the present application, the amount of each component used is different, and the comprehensive performance of Example 1 is better.

[0097] In Examples 6-9 of the present application, the warm mix agent in the asphalt system uses a compound of two surfactants, namely, an alkylamine cationic surfactant and a quaternary ammonium salt amphoteric surfactant, which can improve the lubricity between the components of the asphalt system, further reduce the viscosity of the asphalt system, thereby reducing the asphalt mixing temperature and further reducing the generation of asphalt smoke. At the same time, carboxymethyl cellulose is added to the warm mix agent. From the performance comparison of Example 6 and Example 9, it can be seen that in Example 9, carboxymethyl cellulose is not used, the workability of the asphalt mixture is reduced, resulting in an increase in viscosity and mixing temperature. At the same time, the prepared asphalt will also precipitate and stratify during storage, further indicating that carboxymethyl cellulose can reduce the viscosity of the asphalt mixture during mixing, reduce the generation of asphalt smoke, and improve the storage stability of the asphalt mixture during storage.

[0098] In Examples 10-12, different amounts of titanate coupling agent were added to the asphalt system. From the performance test results, it can be seen that the smoke suppression performance and compatibility of the prepared asphalt are further improved, which further illustrates that the titanate coupling agent can modify the surface of the flame retardant, improve the compatibility of the flame retardant with asphalt, further reduce the asphalt smoke generated by the asphalt mixture, and improve the workability of the asphalt mixture.

[0099] In Examples 13-15, different amounts of sodium stearate were added to the asphalt system. From the performance test results, it can be seen that the viscosity of the prepared warm-mix flame-retardant asphalt is further reduced, and the smoke suppression performance is further improved. Sodium stearate can promote the zinc borate, magnesium aluminum hydroxide and diatomaceous earth in the flame retardant to be evenly dispersed in the asphalt system, reduce the agglomeration of flame retardant particles, thereby improving the workability of the asphalt mixture, reducing the viscosity and mixing temperature of the asphalt mixture, and reducing the phenomenon of excessive viscosity of asphalt during mixing and the generation of asphalt smoke.

[0100] By comparing the performance test results of Comparative Example 1 and Example 1, it can be seen that when acetyl triethyl citrate is not used in the asphalt system, the warm mix flame retardant asphalt prepared in Comparative Example 1 has a lower ductility, reduced resilience and toughness, and the asphalt becomes hard and brittle at low temperatures, shortening the service life of the asphalt road surface. It further illustrates that acetyl triethyl citrate can be combined with a warm mix agent, the warm mix agent reduces the high temperature viscosity of the asphalt mixture, and acetyl triethyl citrate can increase the ductility of the asphalt at low temperatures, so that the asphalt has excellent ductility and toughness in a low temperature environment.

[0101] By comparing the performance test results of Comparative Example 2 and Example 1, it can be seen that Comparative Example 2 does not use acetyl triethyl citrate and warm mix agent in the asphalt system. In actual use, the mixing temperature and paving temperature are significantly higher than those of Example 1, and asphalt smoke is also easily generated, further illustrating that the mixing temperature of the warm mix flame retardant asphalt prepared in Example 1 is significantly reduced, further illustrating the promoting effect of warm mix agent and acetyl triethyl citrate on the asphalt system.

[0102] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A warm mix flame retardant asphalt, characterized in that: The invention comprises the following raw materials in parts by weight: 70-90 parts of asphalt, 1-3 parts of flame retardant, 0.5-1 parts of warm mix agent, 0.3-0.8 parts of triethyl acetyl citrate, 0.3-0.5 parts of titanate coupling agent and 1-3 parts of sodium stearate; the flame retardant is at least one of magnesium aluminum hydroxide, zinc borate and diatomaceous earth; the warm mix agent comprises the following raw materials in parts by weight: 5-8 parts of alkylamine cationic surfactant, 3-5 parts of quaternary ammonium salt amphoteric surfactant and 1-3 parts of carboxymethyl cellulose.

2. The warm mix flame retardant asphalt according to claim 1, characterized in that: The particle size of the diatomaceous earth is 300-400 mesh, and the particle size of the zinc borate is 30-60 nm.

3. A method for preparing warm mix flame retardant asphalt as claimed in any one of claims 1 to 2, characterized in that: The specific steps include: The flame retardant is dried at 100° C. in advance, and then the flame retardant and the titanate coupling agent are mixed and stirred evenly to obtain a modified flame retardant; After the asphalt is heated, a warm mix agent and triethyl acetyl citrate are added and mixed, and then a modified flame retardant and sodium stearate are added and mixed to obtain warm mix flame retardant asphalt.

4. The method for preparing warm mix flame retardant asphalt according to claim 3, characterized in that: The asphalt heating temperature is 100-130°C.

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