Preparation of regenerant carrier and application of regenerant carrier in hot in-place regeneration

Abstract

The invention discloses preparation of a regenerant carrier and application of the regenerant carrier in hot in-place recycling, and relates to the technical field of road engineering. A regenerant is used for regenerating the aged asphalt, and rubber powder is added for modification, so that the low-temperature crack resistance and durability are improved. According to the technical scheme, a regenerant is placed in a high-temperature container, and the regenerant is atomized through high temperature and high pressure; after the regenerant is atomized, the activated rubber powder is placed in the device and is in full contact with the atomized regenerant, a swelling reaction is carried out, and the regenerant is absorbed to form a regenerant carrier. In order to improve the low-temperature crack resistance of the regenerated asphalt mixture, improve the durability of the asphalt mixture and the like, the activated rubber powder is doped to prepare the regenerant carrier, so that the performance of the asphalt mixture regenerated by the regenerant carrier is more excellent.

Description

Technical Field

[0001] The invention relates to the technical field of road engineering, in particular to the field of asphalt pavement maintenance, and relates to a method suitable for the preparation and application of a recycled asphalt mixture. Background Art

[0002] At present, with the rapid development of highway engineering, a large amount of high-quality asphalt materials are urgently needed. Traditional asphalt is a by-product of the oil refining process. The non-renewable nature of oil resources determines the unsustainable nature of asphalt materials. Therefore, the recycling of asphalt is in line with the original intention of current green maintenance. In-situ hot recycling is a technology that heats and raks the asphalt pavement, adds a certain amount of regeneration agent, new asphalt, new asphalt mixture, etc., and then recycles the old asphalt pavement through hot mixing, paving, rolling and other processes to achieve one-time recycling of the old asphalt pavement.

[0003] Traditional asphalt regeneration measures involve in-situ hot regeneration of aged asphalt pavements by adding asphalt regeneration agents. However, as the requirements for low-temperature crack resistance and durability of asphalt continue to increase, asphalt regenerated with traditional regeneration agents can no longer meet the requirements, especially in terms of dynamic stability, failure strain, freeze-thaw splitting strength ratio and failure load. Therefore, how to improve the low-temperature crack resistance and durability of asphalt after in-situ hot regeneration has become a technical problem that needs to be urgently solved by technicians in this field. Summary of the invention

[0004] In view of the above problems, the present invention proposes a regeneration agent carrier preparation and application in on-site thermal regeneration, uses the regeneration agent to regenerate aged asphalt, and modifies it by adding rubber powder to improve low-temperature crack resistance and durability.

[0005] The technical solution of the present invention is: the regeneration agent carrier is formed by mixing activated rubber powder and atomized regeneration agent, the regeneration agent includes rubber oil, diesel, waste engine oil and waste oil, and the mass ratio of each component is 2:2:3:3; the mass ratio of the activated rubber powder and the regeneration agent is 2:3.

[0006] The regeneration agent is placed in a high-temperature container, heated and pressurized to atomize the regeneration agent. After the regeneration agent is atomized, the activated rubber powder is placed in the device to fully contact with the atomized regeneration agent, cause swelling reaction, and absorb the regeneration agent to form a regeneration agent carrier.

[0007] The rubber powder is processed from waste automobile tires, and the preparation method thereof is as follows:

[0008] First, preprocessing:

[0009] The waste tires are finely processed and cut into 80-100 meshes; then the waste rubber powder is extracted with acetone in a Soxhlet extractor for 2 hours, and after the extraction, the waste rubber powder is washed with pure water, dried in an 80°C drying oven to constant weight, and then soaked in 5% sodium hydroxide solution and 10% hydrochloric acid solution for 2 hours and washed respectively, and finally extracted with acetone in a Soxhlet extractor for 2 hours, washed with pure water, and then placed in an 80°C oven to dry to constant weight to obtain pretreated rubber powder;

[0010] Afterwards, the pre-treated rubber powder is activated:

[0011] Use 100 ml of pure water for every 3 g of rubber powder and stir for 5 to 15 minutes. After stirring, pour in 50 ml of sodium hypochlorite and concentrated hydrochloric acid in a volume ratio of 1:1. After standing for 2 hours, wash with pure water and then put it in an oven for drying to obtain the activated rubber powder.

[0012] The regeneration agent carrier is added by direct injection or mixing station addition;

[0013] The first is direct injection, which first adds a predetermined amount of regeneration agent carrier to the original asphalt pavement, then rakes it through the on-site hot regeneration unit, and directly adds a predetermined amount of regeneration agent and new asphalt to the target pavement;

[0014] The second method is the mixing station addition method, which first adds a predetermined amount of regeneration agent to the original asphalt pavement, then raks it through the on-site hot regeneration unit, and adds a predetermined amount of regeneration agent carrier and new asphalt to remix in the mixing station, and then spreads it on the target road surface after remixing.

[0015] The new asphalt is added in an amount of 20% of the original asphalt mass, the regeneration agent is added in an amount of 3-5% of the original asphalt mass, and the regeneration agent carrier is added in an amount of 3-6% of the original asphalt mass.

[0016] The present invention mainly uses the activated rubber powder to fully absorb the regeneration agent, undergo a swelling reaction, form a regeneration agent carrier, and use it in on-site hot regeneration by direct delivery or delivery at a mixing station. Its advantage is that when the regeneration agent is used in on-site hot regeneration, the light component is not able to fully exert the regeneration effect due to the rapid volatilization of the light component due to the high temperature. When the rubber powder is used for absorption to form a regeneration agent carrier, the light component of the regeneration agent can be slowly released, thereby achieving the effect of improving the durability of the asphalt mixture.

[0017] The advantages of the present invention are:

[0018] It can be directly applied to recycled materials in remixing on-site hot regeneration. Rubber powder is easy to contact with asphalt materials, and in the recycled asphalt system modified by the regeneration agent and rubber powder, the aromatic components and light components of asphalt will migrate to the rubber powder to make it swell and form a colloid-like material. Swelling is the key to improving the performance of asphalt. After swelling, the volume of rubber powder will expand to 2 to 4 times of its original size, and it will fill the asphalt phase like elastic balls to play the role of micro-skeleton, thereby improving the low-temperature crack resistance and durability of asphalt.

[0019] In the specific application process, with the introduction of on-site hot regeneration construction, a part of the regeneration agent immediately regenerates the aged asphalt (the pressure work is released during the paving and rolling process), and the other part is stored in the regeneration agent carrier and is continuously released and regenerated with the rolling action of the vehicle.

[0020] In general, in order to improve the low-temperature crack resistance and durability of the regenerated asphalt mixture, the present invention adds activated rubber powder to prepare the regeneration agent carrier, so that the performance of the asphalt mixture after the regeneration agent carrier is regenerated is more excellent. DETAILED DESCRIPTION

[0021] In order to clearly illustrate the technical features of this patent, this patent is elaborated in detail below through a specific implementation method.

[0022] The present invention takes into account that the regeneration of aged asphalt by the regeneration agent has certain limits, and the higher the regeneration agent dosage is not necessarily better. At present, the maximum one-time dosage of the regeneration agent in the industry can only reach 5%, and the durability of the regenerated asphalt mixture has always been a problem.

[0023] Based on this, this case specifically proposes a recycled asphalt system using a regeneration agent carrier. During the construction process, as the asphalt mixture is spread and rolled, part of the regeneration agent carrier will be immediately broken under the rolling action of the roller, allowing the regeneration agent therein to come out and regenerate the aged asphalt; while the unbroken regeneration agent carrier will remain in the asphalt pavement for temporary storage. Thereafter, as vehicles continue to pass by on the road surface, the unbroken regeneration agent carrier will be continuously broken and regenerated under the action of vehicle loads, thereby significantly improving the durability of the regenerated asphalt mixture.

[0024] In the above, the required regeneration agent is a new type of regeneration agent, whose main components are stabilizers, diesel, waste engine oil, gutter oil and other substances. The regeneration principle of the new regeneration agent is to restore the original asphalt performance (mainly supplement the aromatic components) by supplementing the light components of the aged asphalt; wherein the aromatic components of diesel have a relatively high content, and as the main component of the regeneration agent, rubber oil serves as a stabilizer, which fully integrates diesel, waste engine oil, gutter oil and other substances, and can be more fully integrated with the subsequent activated rubber powder to form the regeneration agent carrier required in this case, and finally form a system.

[0025] The dosage of the new regeneration agent in the present invention is:

[0026] Rubber oil: diesel: waste engine oil: gutter oil = 2:2:3:3; they are prepared by rotating and mixing with high-speed rotating equipment, in which rubber oil is a stable component. In addition, rubber oil and rubber powder have similar properties and can be more easily absorbed in the activated rubber powder.

[0027] Considering that waste motor oil and waste cooking oil are regeneration agent materials, there are indeed errors due to the different levels of impurities in them, but the light components, i.e. the target substances, usually account for a higher proportion and have a low proportion of impurities. Therefore, the impurity problem can be ignored after preliminary filtration.

[0028] As an important component of the regeneration agent carrier, that is, the activated rubber powder, the rubber powder selected is waste rubber powder from waste automobile tires in consideration of environmental protection and cost.

[0029] The specific preparation method of the activated rubber powder is:

[0030] First, preprocessing:

[0031] The washed and dried waste automobile tires are finely processed and cut into 80-100 meshes. Then, the waste rubber powder is extracted with acetone in a Soxhlet extractor for 2 hours. After the extraction, the waste rubber powder is washed with pure water, dried in an 80°C drying oven to constant weight, and then soaked in 5% sodium hydroxide solution and 10% hydrochloric acid solution for 2 hours and washed respectively. Finally, acetone is used to extract in a Soxhlet extractor for 2 hours. After washing with a large amount of pure water, it is placed in an 80°C oven and dried to constant weight to obtain pre-treated rubber powder.

[0032] Afterwards, the pre-treated rubber powder is activated:

[0033] First, the pretreated rubber powder is placed under acidic conditions and oxidized in a strong oxidant. The process is as follows: 100 ml of pure water is used for every 3 g of rubber powder, and stirred for 5 to 15 minutes. After stirring, 50 ml of sodium hypochlorite and concentrated hydrochloric acid (ratio 1:1) are poured in, and after standing for 2 hours, the powder is washed with pure water and then placed in an oven for drying to obtain activated rubber powder.

[0034] The advantage of this type of activated rubber powder is that the surface of the waste rubber powder is oxidatively modified by a strong oxidant sodium hypochlorite solution. It mainly relies on the strong oxidizing property of sodium hypochlorite to oxidize double bonds, methylene and other groups on the surface of the waste rubber powder into oxygen-containing groups such as hydroxyl and carbonyl, thereby enhancing the surface activity of the waste rubber powder. When the surface activity of the rubber powder is enhanced, it can be easier to fully contact with the old asphalt mixture.

[0035] Preparation of regeneration agent carrier with activated rubber powder:

[0036] The regeneration agent is placed in a high-temperature container, and sprayed out through a transmission pipeline by a pressure device. The regeneration agent is heated and pressurized to atomize the regeneration agent. When the regeneration agent is pressurized and atomized at 60-100°C, the activated rubber powder is placed in the device to make it fully contact with the atomized regeneration agent, and a swelling reaction occurs, absorbing the regeneration agent to form a regeneration agent carrier; avoiding the problem of easy volatilization of light components, poor durability of asphalt mixture after regeneration, and insufficient low-temperature crack resistance.

[0037] The prepared regeneration agent carrier is mainly used in on-site hot regeneration projects. In the project, the amount of new asphalt is 20% of the original asphalt mass, the amount of regeneration agent is 3-5% of the original asphalt mass, and the amount of regeneration agent carrier is 3-6% of the original asphalt mass. There are two ways to put the regeneration agent carrier:

[0038] The first is direct injection, which first adds a predetermined amount of regeneration agent carrier to the original asphalt pavement, then rakes it through the on-site hot regeneration unit, and directly adds a predetermined amount of regeneration agent and new asphalt to the target pavement;

[0039] The second method is the mixing station addition method, which first adds a predetermined amount of regeneration agent to the original asphalt pavement, then raks it through the on-site hot regeneration unit, and adds a predetermined amount of regeneration agent carrier and new asphalt to remix in the mixing station, and then spreads it on the target road surface after remixing.

[0040] Since the above-mentioned on-site hot regeneration unit is an existing technology and has functions such as heating, raking, spraying, and paving, the structure of the on-site hot regeneration unit will not be described in detail in this case.

[0041] The amount of rubber powder added is 0.1% of the original pavement asphalt mixture mass. The amount of hot asphalt added is determined based on the asphalt oil-stone ratio deficiency of the original pavement material. According to engineering experience, the amount of new asphalt added is generally 0.5% for remixing and on-site hot recycling.

[0042] By comparing the performance of asphalt mixture after adding rubber powder regeneration agent carrier and asphalt mixture after general regeneration agent regeneration, the technical indicators are shown in the following table:

[0043]

[0044] There are many specific implementation ways of the present invention. The above is only the preferred implementation mode of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements can be made without departing from the principle of the present invention. These improvements should also be regarded as the protection scope of the present invention.

Claims

1. A regeneration agent carrier, characterized in that: The regeneration agent carrier is formed by mixing activated rubber powder and atomized regeneration agent, the regeneration agent includes rubber oil, diesel, waste engine oil and waste cooking oil, and the mass ratio of each component is 2:2:3:3; the mass ratio of the activated rubber powder and the regeneration agent is 2:

3.

2. A method for preparing a regeneration agent carrier according to claim 1, characterized in that: The regeneration agent is placed in a high-temperature container, heated and pressurized to atomize the regeneration agent. After the regeneration agent is atomized, the activated rubber powder is placed in the device to fully contact with the atomized regeneration agent, cause swelling reaction, and absorb the regeneration agent to form a regeneration agent carrier.

3. The method for preparing a regeneration agent carrier according to claim 2, characterized in that: The rubber powder is processed from waste automobile tires, and the preparation method thereof is as follows: First, preprocessing: The waste tires are finely processed and cut into 80-100 meshes; then the waste rubber powder is extracted with acetone in a Soxhlet extractor for 2 hours, and after the extraction, the waste rubber powder is washed with pure water, dried in a drying oven at 80°C to constant weight, and then soaked in 5% sodium hydroxide solution and 10% hydrochloric acid solution for 2 hours and washed respectively, and finally extracted with acetone in a Soxhlet extractor for 2 hours, washed with pure water, and then dried in an oven at 80°C to constant weight to obtain pretreated rubber powder; Afterwards, the pre-treated rubber powder is activated: Use 100 ml of pure water for every 3 g of rubber powder and stir for 5 to 15 minutes. After stirring, pour in 50 ml of sodium hypochlorite and concentrated hydrochloric acid in a volume ratio of 1:

1. After standing for 2 hours, wash with pure water and then put it in an oven for drying to obtain the activated rubber powder.

4. A method for using the regeneration agent carrier prepared according to claim 1 in in-situ thermal regeneration, characterized in that: The regeneration agent carrier is added by direct injection or mixing station addition; The first is direct injection, which first adds a predetermined amount of regeneration agent carrier to the original asphalt pavement, then rakes it through the on-site hot regeneration unit, and directly adds a predetermined amount of regeneration agent and new asphalt to the target pavement; The second method is the mixing station addition method, which first adds a predetermined amount of regeneration agent to the original asphalt pavement, then raks it through the on-site hot regeneration unit, and adds a predetermined amount of regeneration agent carrier and new asphalt to remix in the mixing station, and then spreads it on the target road surface after remixing.

5. The method for using a regeneration agent carrier in in-situ thermal regeneration according to claim 4, characterized in that: The new asphalt is added in an amount of 20% of the original asphalt mass, the regeneration agent is added in an amount of 3-5% of the original asphalt mass, and the regeneration agent carrier is added in an amount of 3-6% of the original asphalt mass.

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