Background
Asphalt pavement is widely used in highway construction because of its advantages of smooth surface, no expansion joint, comfortable driving, low noise, easy construction and maintenance, etc. The common petroleum asphalt is mainly adopted to pave the road surface at home and abroad in the early stage, but the high-low temperature performance of the road surface is poor, the road surface is easy to have track, pit and crack and other diseases, and is easy to be seriously damaged particularly under the condition of heavy-load traffic, and the service life of the road surface is short. In order to prolong the service life of asphalt pavements, styrene and butadiene triblock thermoplastic elastomer (SBS) modified asphalt is applied to pavements from the nineties of the last century at home and abroad so as to improve the low-temperature crack resistance and high-temperature rutting resistance of the asphalt pavements.
Although the SBS modified asphalt has excellent high and low temperature performance, the modified asphalt pavement still receives the action of factors such as strong ultraviolet light, heat, oxygen and the like in the service process, so that the SBS modified asphalt is aged to cause pavement diseases, and the pavement also needs to be maintained or rebuilt, thereby generating a large amount of waste SBS modified asphalt mixture. The waste SBS modified asphalt mixture is recycled, so that a large amount of raw materials such as asphalt and stone can be saved, the influence of stone exploitation on the environment is reduced, the environment protection is facilitated, and the method has very remarkable social, economic and environmental benefits.
The cross-linked network structure formed by SBS in asphalt is the main reason that the modified asphalt has excellent high and low temperature performance. After the SBS modified asphalt is aged, the molecular structure of the modifier SBS is damaged, the original modification effect is lost, and the engineering performance of the SBS modified asphalt is deteriorated. In recent ten years, the regeneration of the aged SBS modified asphalt mainly adopts the traditional regeneration technology, such as directly adding organic oily components such as high aromatic hydrocarbon oil, waste vegetable oil, waste edible oil and illegal cooking oil, so as to supplement light components lost by the aging of the asphalt and improve the overall performance of the aged SBS modified asphalt. Although the technologies have better promotion effects on the characteristics of aged SBS modified asphalt, such as low temperature, fatigue and the like, the high-temperature performance and the adhesiveness of the regenerated SBS modified asphalt are difficult to reach or approach the performance level of the original SBS modified asphalt, so that the application of high-quality engineering of the reaction regenerated SBS modified asphalt is greatly limited.
Disclosure of Invention
In order to solve the defects of the prior art, the invention provides a reaction-regenerated SBS modified asphalt and a preparation method thereof.
The technical scheme provided by the invention is as follows:
a preparation method of SBS modified asphalt regenerated by reaction comprises the following steps:
1) obtaining aged SBS modified asphalt, diisocyanate structural repair agent, diepoxy structural repair agent and asphalt regenerant;
2) heating the aged SBS modified asphalt to 140-160 ℃, adding an asphalt regenerant at a stirring speed of 200-400rpm, and stirring, wherein the weight percentage of the asphalt regenerant to the aged SBS modified asphalt is 4-6%;
3) sequentially adding the diisocyanate structure repairing agent and the diepoxy structure repairing agent into the mixture obtained in the step 2), and stirring and reacting at the temperature of 140-160 ℃ and the stirring speed of 200-400rpm to prepare the SBS modified asphalt regenerated by reaction, wherein the weight percentage of the diisocyanate structure repairing agent to the aged SBS modified asphalt is 1-1.5%, and the weight percentage of the diepoxy structure repairing agent to the aged SBS modified asphalt is 1-2%.
In the technical scheme, if the diisocyanate structure repairing agent is singly added, the softening point of the SBS modified asphalt regenerated by reaction is greatly increased, and the low-temperature performance is damaged. If the diepoxy structure repairing agent is singly added, the ductility of the SBS modified asphalt regenerated by the reaction is only improved. However, the inventor finds that the simultaneous addition of the two repairing agents can avoid the excessively high softening point of the SBS modified asphalt to approach the original asphalt, thereby ensuring the high-temperature performance, the low-temperature performance and the ductility of the SBS modified asphalt regenerated by reaction.
Specifically, the diisocyanate structural repair agent is 4, 4-diphenylmethane diisocyanate.
The invention utilizes the selective reaction capability of the isocyanate end group in the molecular structure of the 4, 4-diphenylmethane diisocyanate to bond the SBS oxidation degradation product part, promotes the molecular weight of the SBS modified asphalt regenerated by reaction to be increased, and simultaneously leads the high-temperature performance of the SBS modified asphalt regenerated by reaction to be obviously improved based on the steric hindrance of the benzene ring structure.
Specifically, the diepoxy structure repair agent is 1, 4-butanediol diglycidyl ether.
The invention utilizes the addition of 1, 4-butanediol diglycidyl ether and a common asphalt regenerant to promote the aged SBS modified asphalt to have higher fluidity at the regeneration processing temperature (150 ℃), and achieves the purpose of improving the low-temperature characteristic of the aged SBS modified asphalt through the physical and chemical interaction with the aged SBS modified asphalt.
Specifically, the asphalt regenerant is aromatic oil.
The preparation method of the SBS modified asphalt regenerated by reaction comprises the following specific steps:
1) weighing 100g of aged SBS modified asphalt, 1-1.5 g of 4, 4-diphenylmethane diisocyanate and/or 1-2 g of 1, 4-butanediol diglycidyl ether and 5g of aromatic oil according to the mass ratio of the raw materials for later use.
2) Heating the aged asphalt to 150 ℃, adding aromatic oil at a stirring speed of 200-400rpm, and stirring for 5 min;
3) and sequentially adding 4, 4-diphenylmethane diisocyanate and 1, 4-butanediol diglycidyl ether into the mixture, keeping the temperature and the stirring speed unchanged, and continuing to react for 5min to prepare the SBS modified asphalt regenerated by reaction.
The invention also provides the SBS modified asphalt regenerated by the preparation method of the SBS modified asphalt regenerated by the reaction.
The reactive compound and the common asphalt regenerant are utilized to carry out the synergistic regeneration on the aged SBS modified asphalt, so that the high-quality SBS modified asphalt which can be subjected to reaction regeneration and can be applied can be prepared, the high-performance recycling of the waste SBS modified asphalt mixture is realized, and the obvious engineering value, economic benefit and environmental benefit are achieved.
Detailed Description
The principles and features of this invention are described below in conjunction with examples which are set forth to illustrate, but are not to be construed to limit the scope of the invention.
In the invention, SBS modified asphalt (ductility at 5 ℃ of 36.8cm, softening point of 70.5 ℃, needle penetration at 25 ℃ of 48.3dmm and viscosity at 135 ℃ of 2.56 Pa.s) is put in a film oven (TFOT) for aging for 5h, and then the ultraviolet light intensity is 1300 mu W/cm-1And continuously irradiating for 14 days in an ultraviolet aging box (the wavelength of ultraviolet light is 365nm) at the temperature of 40 ℃ to obtain the aged SBS modified asphalt. The aging process mainly simulates the thermal aging of SBS modified asphalt in concrete mixing and paving and the aging process of SBS modified asphalt subjected to long-term ultraviolet radiation in the service process. After aging, the SBS modified asphalt had a 5 ℃ ductility of 6.6cm, a softening point of 61.8 ℃, a 25 ℃ penetration of 30.8dmm and a 135 ℃ viscosity of 4.04 pas. The aged SBS modified asphalt from this test was used in each of the following examples.
Example 1
100g of aged SBS modified asphalt heated to a molten state is weighed, after the temperature is stabilized at 150 ℃, 1g of 4, 4-diphenylmethane diisocyanate is added, and the mixture is stirred for 5min at a stirring speed of 300rpm, so that the SBS modified asphalt regenerated by reaction is prepared. The physical properties of the SBS modified asphalt regenerated by reaction were tested according to the test protocol for road engineering asphalt and asphalt mixture (JTJE20-2011), and the SBS modified asphalt regenerated by reaction had a softening point of 69.8 ℃, an ductility of 6.8cm at 5 ℃, a penetration of 29.2dmm at 25 ℃ and a viscosity of 4.21 Pa.s at 135 ℃.
The test results show that the 4, 4-diphenylmethane diisocyanate mainly has the effect of improving the softening point of the aged SBS modified asphalt, but has no effect of improving the low-temperature ductility and the working characteristics.
Example 2
Weighing 100g of aged SBS modified asphalt heated to a molten state, adding 1g of 1, 4-butanediol diglycidyl ether after the temperature is stabilized at 150 ℃, and continuously stirring at a stirring speed of 300rpm for 5min to prepare the SBS modified asphalt regenerated by reaction. The physical properties of the SBS modified asphalt regenerated by reaction were tested according to the test protocol for road engineering asphalt and asphalt mixture (JTJE20-2011), and the SBS modified asphalt regenerated by reaction had an extensibility of 18.9cm at 5 ℃, a softening point of 58.4 ℃, a penetration of 39.8dmm at 25 ℃ and a viscosity of 2.29 Pa.s at 135 ℃.
From the test results, the 1, 4-butanediol diglycidyl ether mainly has the effect of improving the low-temperature ductility and the working characteristics of the aged SBS modified asphalt, but can reduce the high-temperature performance of the aged SBS modified asphalt to a certain extent.
Example 3
Weighing 100g of aged SBS modified asphalt heated to a molten state, adding 1g of 4, 4-diphenylmethane diisocyanate at a stirring speed of 300rpm after the temperature is stabilized at 150 ℃, adding 1g of 1, 4-butanediol diglycidyl ether after 5min, and continuously stirring for 5min to prepare the SBS modified asphalt regenerated by reaction. The physical properties of the reactively recycled SBS modified asphalt were tested according to road engineering asphalt and asphalt mixture testing protocol (JTJE20-2011), and the reactively recycled SBS modified asphalt had a ductility of 18.1cm at 5 ℃, a softening point of 67.2 ℃, a penetration of 34.6dmm at 25 ℃ and a viscosity of 3.02 Pa.s at 135 ℃.
From the test results, it can be seen that comparative examples 1 and 2, 4, 4-diphenylmethane diisocyanate and 1, 4-butanediol diglycidyl ether have complementary advantages in the regeneration of aged SBS-modified asphalt, and also improve the high and low temperature properties of the aged SBS-modified asphalt.
Example 4
Weighing 100g of aged SBS modified asphalt heated to a molten state, adding 1g of 4, 4-diphenylmethane diisocyanate at a stirring speed of 300rpm after the temperature is stabilized at 150 ℃, adding 1.5g of 1, 4-butanediol diglycidyl ether after 5min, and continuously stirring for 5min to obtain the SBS modified asphalt regenerated by reaction. The physical properties of the SBS modified asphalt regenerated by reaction were tested according to the test protocol for road engineering asphalt and asphalt mixture (JTJE20-2011), and the SBS modified asphalt regenerated by reaction had a ductility at 5 ℃ of 23.3cm, a softening point of 65.1 ℃, a penetration at 25 ℃ of 42.4dmm, and a viscosity at 135 ℃ of 2.56 Pa.s.
From the test results, it can be seen that the increase in the amount of 1, 4-butanediol diglycidyl ether added in comparative example 3 further improves the low-temperature ductility and the working characteristics of the aged SBS-modified asphalt regenerated from 4, 4-diphenylmethane diisocyanate, without seriously deteriorating the high-temperature performance.
Example 5
Weighing 100g of aged SBS modified asphalt heated to a molten state, adding 1g of 4, 4-diphenylmethane diisocyanate at a stirring speed of 300rpm after the temperature is stabilized at 150 ℃, adding 2g of 1, 4-butanediol diglycidyl ether after 5min, and continuously stirring for 5min to obtain the SBS modified asphalt regenerated by reaction. The physical properties of the reactively recycled SBS modified asphalt were tested according to road engineering asphalt and asphalt mixture testing protocol (JTJE20-2011), and the reactively recycled SBS modified asphalt had a ductility of 27.8cm at 5 ℃, a softening point of 63.5 ℃, a penetration of 46.5dmm at 25 ℃ and a viscosity of 2.21 Pa.s at 135 ℃.
From the test results, it can be seen that in comparative examples 3 and 4, with the further increase of the amount of the 1, 4-butanediol diglycidyl ether, the low-temperature performance and the working characteristics of the recycled modified SBS modified asphalt are improved, and the softening point can still be kept at a higher level.
Example 6
Weighing 100g of aged SBS modified asphalt heated to a molten state, adding 1.5g of 4, 4-diphenylmethane diisocyanate at a stirring speed of 300rpm after the temperature is stabilized at 150 ℃, adding 2g of 1, 4-butanediol diglycidyl ether after 5min, and continuously stirring for 5min to obtain the SBS modified asphalt regenerated by reaction. The physical property test of the SBS modified asphalt regenerated by the reaction is carried out according to the test specification of road engineering asphalt and asphalt mixture (JTJE20-2011), and the SBS modified asphalt regenerated by the reaction has the ductility of 25.2cm at 5 ℃, the softening point of 65.8 ℃, the penetration of 34.9dmm at 25 ℃ and the viscosity of 2.83 Pa.s at 135 ℃.
From the test results, it can be seen that in comparative example 5, 4, 4-diphenylmethane diisocyanate mainly exhibits an inhibitory effect on the decrease in the high-temperature performance of the aged SBS-modified asphalt after the synergistic regeneration, under the action of the above two reactive compounds.
Example 7
Weighing 100g of aged SBS modified asphalt heated to a molten state, adding 5g of aromatic oil at a stirring speed of 300rpm after the temperature is stabilized at 150 ℃, adding 1g of 4, 4-diphenylmethane diisocyanate after 5min, adding 1g of 1, 4-butanediol diglycidyl ether, and continuously stirring for 5min to obtain the SBS modified asphalt regenerated by reaction. The physical properties of the reactively recycled SBS modified asphalt were tested according to the road engineering asphalt and asphalt mixture test protocol (JTJE20-2011), and the reactively recycled SBS modified asphalt had a ductility of 24.5cm at 5 ℃, a softening point of 65.1 ℃, a penetration of 43.9dmm at 25 ℃ and a viscosity of 2.53Pa · s at 135 ℃.
From the test results, it can be seen that in comparative example 3, the aromatic oil mainly acts as a softening effect on the aged asphalt, so that the low temperature ductility and the working properties of the SBS modified asphalt regenerated by the synergistic reaction are improved.
Example 8
Weighing 100g of aged SBS modified asphalt heated to a molten state, adding 5g of aromatic oil at a stirring speed of 300rpm after the temperature is stabilized at 150 ℃, adding 1.5g of 4, 4-diphenylmethane diisocyanate after 5min, then adding 2g of 1, 4-butanediol diglycidyl ether, and continuing stirring for 5min to prepare the SBS modified asphalt regenerated by reaction. The physical properties of the reactively recycled SBS modified asphalt were tested according to the road engineering asphalt and asphalt mixture test protocol (JTJE20-2011), and the reactively recycled SBS modified asphalt had a ductility at 5 ℃ of 32.5cm, a softening point of 63.1 ℃, a penetration at 25 ℃ of 42.8dmm, and a viscosity at 135 ℃ of 2.13Pa · s.
From the test results, it can be seen that in comparative examples 6 and 7, under the synergistic effect of 4, 4-diphenylmethane diisocyanate, 1, 4-butanediol diglycidyl ether and aromatic oil, the high and low temperature performances of the aged SBS modified asphalt are improved to a degree close to the performance level of the original SBS modified asphalt.
As can be seen from the above examples, the effects of 4, 4-diphenylmethane diisocyanate and 1, 4-butanediol diglycidyl ether on the high and low temperature properties of aged SBS-modified asphalt are significantly different. If the dosage of a certain SBS molecular structure repairing agent is simply increased, the high-temperature performance or the low-temperature performance of the aged SBS modified asphalt can be improved unilaterally, but the effect of taking account of both the high-temperature performance and the low-temperature performance cannot be obtained. Therefore, 4-diphenylmethane diisocyanate and 1, 4-butanediol diglycidyl ether are used cooperatively, and aromatic oil is added to adjust the aged matrix asphalt component, so that the overall performance of the aged SBS modified asphalt can be promoted to be close to the original asphalt level, and the high-quality engineering application is met.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.