A semi-flexible pavement material with enhanced interface self-healing properties and its maintenance method

Abstract

The present invention discloses an interface self-healing enhanced semi-flexible pavement material and its maintenance method, belonging to the technical field of road engineering materials. The interface self-healing enhanced semi-flexible pavement material of the present invention comprises a cement-based grouting material and the following raw materials in parts by weight: 7-8 parts modified porous asphalt mixture and 0.05-0.1 parts semi-flexible pavement interface self-healing microcapsules. The interface self-healing enhanced semi-flexible pavement material of the present invention has the advantages of high mechanical properties and strong interface self-healing ability.

Description

Technical Field

[0001] The present invention relates to the technical field of road engineering materials, and in particular to an interface self-healing enhanced semi-flexible pavement material and a maintenance method thereof. Background Art

[0002] Semi-flexible pavement material is a composite material formed by injecting a cement-based grouting material into a porous asphalt mixture with large voids. Due to its significant advantages, such as high load-bearing capacity, good rutting resistance, and excellent durability, this material has been widely used in heavy-load and heavy-traffic areas such as bus stops, BRT lanes, and intersections. However, during service, the poor compatibility between the cement-based grouting material and the asphalt mixture can lead to a decrease in adhesion at the composite interface, resulting in cracking.

[0003] The existing method of enhancing the composite interface of semi-flexible pavement is mainly to modify the asphalt interface by adding an interfacial emulsifier to enhance the anti-cracking effect of the inorganic-organic interface. For example, by introducing a polymer emulsion, the interfacial adhesion is improved and has good adhesion, but this method has the disadvantages of a slow asphalt emulsification process and a long cement curing cycle, which seriously affects the construction efficiency. In addition, some active groups with self-repairing functions fail when reacting with the emulsion, which will have a negative impact on the long-term service of the asphalt material. Some methods also use a composite structure to connect the cement-asphalt interface to form an "external bridge" to enhance the interface connection ability. For example, the use of modified fiber materials to connect the cement-asphalt interface can enhance the interface connection ability, but the fiber modification cost is high and the process is cumbersome. In addition, the above solutions only improve the bonding strength of the interface, and still have the problems of insufficient self-healing performance and limited long-term service effect. Summary of the Invention

[0004] The purpose of the present invention is to provide an interface self-healing enhanced semi-flexible pavement material and a maintenance method thereof to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is: an interface self-healing enhanced semi-flexible pavement material, comprising a cement-based grouting material and the following raw materials in parts by weight: 7 to 8 parts of a modified porous asphalt mixture and 0.05 to 0.1 parts of semi-flexible pavement interface self-healing microcapsules;

[0007] The modified porous asphalt mixture comprises the following raw materials in parts by weight: 10 to 20 parts of porous asphalt matrix, 48 to 62 parts of aggregate, 2.0 to 2.5 parts of high-viscosity particles, and 0.3 to 0.5 parts of steel wool fiber;

[0008] The semi-flexible pavement interface self-healing microcapsule is composed of a capsule core and a capsule wall;

[0009] The capsule core comprises the following raw materials in parts by weight: 8 to 15 parts of Bacillus bacterial liquid, 1.0 to 1.5 parts of adhesive biopolymer, 2.0 to 2.5 parts of urea and 4 to 5 parts of calcium chloride;

[0010] The raw material of the capsule wall includes ethyl cellulose.

[0011] Furthermore, the aggregate consists of coarse aggregate, fine aggregate and filler.

[0012] Furthermore, the modified porous asphalt mixture comprises the following raw materials in parts by weight: 10-20 parts of porous asphalt matrix, 40-50 parts of coarse aggregate, 5-8 parts of fine aggregate, 3-4 parts of filler, 2.0-2.5 parts of high viscosity particles and 0.3-0.5 parts of steel wool fiber;

[0013] The capsule core comprises the following raw materials in parts by weight: 8 to 15 parts of Bacillus liquid, 3 to 4 parts of yeast powder, 1.0 to 1.5 parts of viscous biopolymer, 2.0 to 2.5 parts of urea, and 4 to 5 parts of calcium chloride;

[0014] The capsule wall comprises the following raw materials in parts by weight: 80-100 parts of cyclohexane, 2.0-2.5 parts of ethyl cellulose and 0.45-0.65 parts of polyethylene.

[0015] Furthermore, the steel wool fiber has a length of 6.5 mm and a diameter of 8.89 to 12.7 μm;

[0016] The porosity of the porous asphalt matrix is ​​25-35%, and the interconnected porosity is 18-28%.

[0017] Furthermore, the coarse aggregate includes at least one of basalt, diabase and limestone; the particle size of the coarse aggregate is 4.75 to 13.2 mm;

[0018] The fine aggregate comprises at least one of basalt, diabase and limestone; the particle size of the fine aggregate is less than 2.36 mm;

[0019] The filler comprises limestone powder; the pass rate of the limestone powder in the particle size range of 0.15 mm is greater than 90%, and the pass rate of 0.075 mm is greater than 75%.

[0020] Furthermore, the preparation method of the modified porous asphalt mixture comprises the following steps:

[0021] After melting the porous asphalt matrix, steel wool fibers and high-viscosity particles are added, heated and stirred to swell, and then sheared at high speed to obtain modified porous asphalt;

[0022] The aggregate and the modified porous asphalt are heated and mixed evenly to obtain the modified porous asphalt mixture.

[0023] Further, the adhesive biopolymer includes at least one of xanthan gum, gum arabic, guar gum and carrageenan;

[0024] The capsule core is in granular form with a particle size of 50 to 100 microns.

[0025] Furthermore, the Bacillus bacterial solution includes Bacillus pasteurianus bacterial solution, and the bacterial concentration of the Bacillus pasteurianus bacterial solution is 1.1 to 1.6×10 10 / mL.

[0026] Furthermore, the mass ratio of the capsule core to the ethyl cellulose is 1:(1.5-2).

[0027] Furthermore, the preparation method of the semi-flexible pavement interface self-healing microcapsules is selected from one of the following methods:

[0028] Method 1 comprises: mixing a bacillus bacterial liquid with a viscous biopolymer, urea, and calcium chloride to form a mass to obtain a capsule core;

[0029] The semi-flexible pavement interface self-healing microcapsules are obtained by adding ethyl cellulose into a solvent, heating and dissolving the cellulose, adding a capsule core and a silane coupling agent, mixing the mixture evenly, and cooling and solidifying the mixture.

[0030] Method 2 comprises: mixing a bacillus bacterial liquid with a viscous biopolymer, urea, calcium chloride, and yeast powder to form a mass to obtain a capsule core;

[0031] Cyclohexane, ethyl cellulose and polyethylene are mixed, heated to dissolve, and then capsule cores and silane coupling agents are added, mixed evenly, and cooled to solidify to obtain the semi-flexible pavement interface self-healing microcapsules.

[0032] The second technical solution of the present invention is a method for preparing the above-mentioned interface self-healing enhanced semi-flexible pavement material, comprising the following steps:

[0033] The modified porous asphalt mixture is hot-mixed and evenly paved, and then the semi-flexible pavement interface self-healing microcapsules are placed in the gaps of the modified porous asphalt mixture. After cooling, cement-based grouting material is poured, solidified, and maintained to obtain the interface self-healing enhanced semi-flexible pavement material.

[0034] Furthermore, the curing includes: curing under standard curing conditions, or natural curing after spraying water retention curing, and then heating treatment.

[0035] Furthermore, the temperature of the heating treatment (electromagnetic induction heating treatment) is 60-70°C, and the heating depth is 3-5 cm;

[0036] Before spraying the water-retaining curing agent, the relative humidity of the interface self-healing enhanced semi-flexible pavement material is adjusted to ≥80%.

[0037] Technical solution three of the present invention: A maintenance method for an interface self-healing enhanced semi-flexible pavement material, comprising the following steps:

[0038] When cracks initially appear on the surface of the above-mentioned interface self-healing enhanced semi-flexible pavement material, a water-retaining curing agent is sprayed on the surface, and after natural curing, a heating treatment is performed, and after cooling, a grouting treatment is performed, and the material is smoothed and then rolled.

[0039] Furthermore, the temperature of the heating treatment (electromagnetic induction heating treatment) is 60-70°C, and the heating depth is 3-5 cm;

[0040] Before spraying the water-retaining curing agent, the relative humidity of the interface self-healing enhanced semi-flexible pavement material is adjusted to ≥80%.

[0041] The present invention discloses the following technical effects:

[0042] (1) The interface self-healing enhanced semi-flexible pavement material of the present invention has the advantages of high mechanical properties and strong interface self-healing ability.

[0043] (2) The viscous biopolymer in the semi-flexible pavement interface self-healing microcapsules of the present invention can promote the cementation process of carbonate precipitation induced by microorganisms after the microcapsules are ruptured, thereby enhancing the self-healing ability of various materials at the cement-asphalt interface and achieving efficient service of the semi-flexible pavement (which can serve for up to 15 years). For example, xanthan gum is often in a polyanionic state in aqueous solution, and the side chain carboxyl group of the anionic biopolymer carries a negative charge, which can attract a large amount of Ca 2+ ions, and Ca 2+ Form chemical bonds, thereby promoting the formation of calcium carbonate crystals; and, xanthan gum exhibits high viscosity through intramolecular and intermolecular non-covalent bonds, enabling it to connect the cement-asphalt interface after the microcapsules rupture, and enhance the self-healing ability of the asphalt interface by increasing the local viscosity of the asphalt material.

[0044] (3) The steel wool fiber added to the modified porous asphalt of the present invention can form a connecting bridge at the interface between cement and asphalt, optimize the adhesion of the composite interface to a certain extent, and enhance the bending resistance of the semi-flexible pavement material. At the same time, the steel wool fiber can be subjected to electromagnetic induction heating to increase the temperature of the interface. On the one hand, it increases the fluidity of the asphalt to fill the interface cracks and achieve the self-healing effect of the asphalt; on the other hand, the steel wool fiber induction heating process can enhance the bonding process of MICP after the microcapsule ruptures, thereby improving the self-healing effect of the cement interface. The process is divided into two stages. In the first stage, electromagnetic induction heating raises the interface temperature to 60-70°C, significantly improves the activity of microbial urease, accelerates metabolism, promotes urea hydrolysis, generates NH3 and CO2 that dissolve in water, and increases the pH of the solution and the concentration of soluble inorganic carbon in the solution; in the second stage, the heating is completed, the temperature drops to room temperature, and in an alkaline environment, HCO3 in the solution - and Ca 2+ The bonding rate is accelerated, and calcium carbonate precipitation is generated to fill the cracks. This method can be used repeatedly, thereby enhancing the long-term and efficient self-healing ability of the pavement material interface.

[0045] (4) Asphalt is sticky, and there are highly sticky particles at the interface, which can effectively fix the microcapsules, making them less likely to be blown away by the airflow after contacting the interface; the microcapsule wall material contains silane coupling agent, and the free siloxy groups in the silane coupling agent can effectively adsorb the oil and resin in the asphalt, thereby ensuring good bonding performance between the asphalt mixture matrix and the self-healing microcapsules at the semi-flexible pavement interface, thereby reducing the aggregation and loss of microcapsules and further increasing the retention of microcapsules at the asphalt interface.

[0046] (5) The method of the present invention of using a pneumatic spray gun to evenly spray interface self-healing microcapsules into the voids of porous asphalt mixture is simple to operate, can significantly increase the utilization rate of interface self-healing microcapsules on the interface of semi-flexible pavement, achieve a better interface directional self-healing enhancement effect, and further improve the road performance of semi-flexible pavement materials.

[0047] (6) The present invention uses a pneumatic spray gun to evenly spray interface self-healing microcapsules into the voids of porous asphalt mixtures, so that the microcapsules act precisely on the composite interface. The microorganisms in the microcapsules and the electromagnetic induction heating work synergistically to enhance the self-healing properties of cement and asphalt in the composite interface, enhance the initial fusion strength of the interface and the crack adhesion performance (the interface adhesion strength can be increased by 50%), solve the problem of cracking of the composite interface of traditional semi-flexible pavement, and achieve efficient self-repair and high-performance long-term service of pavement materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0049] Figure 1 Schematic diagram of the working principle of the interface self-healing enhanced semi-flexible pavement material, where (a) is before repair and (b) is during the repair process. DETAILED DESCRIPTION

[0050] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0051] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0052] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0053] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0054] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0055] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in this field and are not the focus of the present invention.

[0056] In a first aspect, the present invention provides an interface self-healing enhanced semi-flexible pavement material, comprising a cement-based grouting material and the following raw materials in parts by weight: 7 to 8 parts of a modified porous asphalt mixture and 0.05 to 0.1 parts of semi-flexible pavement interface self-healing microcapsules;

[0057] The modified porous asphalt mixture comprises the following raw materials in parts by weight: 10-20 parts of porous asphalt matrix, 48-62 parts of aggregate, 2.0-2.5 parts of high viscosity particles and 0.3-0.5 parts of steel wool fiber;

[0058] Semi-flexible pavement interface self-healing microcapsules consist of a capsule core and a capsule wall;

[0059] The capsule core comprises the following raw materials in parts by weight: 8 to 15 parts of Bacillus bacterial liquid, 1.0 to 1.5 parts of adhesive biopolymer, 2.0 to 2.5 parts of urea and 4 to 5 parts of calcium chloride;

[0060] The raw materials of the capsule wall include ethyl cellulose.

[0061] In a specific embodiment of the present invention, the aggregate consists of coarse aggregate, fine aggregate and filler.

[0062] In a specific embodiment of the present invention, the modified porous asphalt mixture comprises the following raw materials in parts by weight: 10-20 parts of porous asphalt matrix, 40-50 parts of coarse aggregate, 5-8 parts of fine aggregate, 3-4 parts of filler, 2.0-2.5 parts of high viscosity particles and 0.3-0.5 parts of steel wool fiber;

[0063] The capsule core comprises the following raw materials in parts by weight: 8 to 15 parts of Bacillus liquid, 3 to 4 parts of yeast powder, 1.0 to 1.5 parts of adhesive biopolymer, 2.0 to 2.5 parts of urea, and 4 to 5 parts of calcium chloride;

[0064] The capsule wall comprises the following raw materials in parts by mass: 80-100 parts of cyclohexane, 2.0-2.5 parts of ethyl cellulose and 0.45-0.65 parts of polyethylene.

[0065] The function of yeast powder is to provide nutrients for Bacillus. Not adding yeast powder will not affect the realization of technical effects.

[0066] In a specific embodiment of the present invention, the steel wool fiber has a length of 6.5 mm and a diameter of 8.89 to 12.7 μm;

[0067] The porosity of the porous asphalt matrix is ​​25-35%, and the interconnected porosity is 18-28%.

[0068] In a specific embodiment of the present invention, the coarse aggregate includes at least one of basalt, diabase and limestone, preferably basalt; the particle size of the coarse aggregate is 4.75 to 13.2 mm;

[0069] The fine aggregate comprises at least one of basalt, diabase and limestone, preferably limestone; the particle size of the fine aggregate is less than 2.36 mm;

[0070] The filler includes limestone powder; the particle size range of the limestone powder is 0.15 mm, the passing rate of which is greater than 90%, and the passing rate of which is 0.075 mm, which is greater than 75%.

[0071] In a specific embodiment of the present invention, the method for preparing the modified porous asphalt mixture comprises the following steps:

[0072] (1) The porous asphalt matrix is ​​heated at 180°C to melt it into a liquid state, while the steel wool fibers and high-viscosity particles are preheated at 150°C;

[0073] (2) Steel wool fibers and high-viscosity particles were added to the porous asphalt matrix and stirred at 180°C and 250 r / min for 30 min to allow the particles to fully swell;

[0074] (3) High-speed shearing at a speed of 4000 r / min for 30 min to ensure uniform mixing of steel wool fibers, high-viscosity particles and porous asphalt matrix to obtain modified porous asphalt;

[0075] (4) Preheating aggregate and modified porous asphalt at 150°C;

[0076] (5) Setting the temperature of the stirring pot to 180-190°C and the speed to 80-100 r / min, stirring the aggregate in the stirring pot for 30-60 seconds, then adding the modified porous asphalt and stirring for 60-90 seconds, and finally adding the filler and stirring for 60-90 seconds to obtain the modified porous asphalt mixture;

[0077] In a specific embodiment of the present invention, the adhesive biopolymer comprises at least one of xanthan gum, gum arabic, guar gum and carrageenan, preferably xanthan gum;

[0078] The capsule core is granular with a particle size of 50 to 100 microns.

[0079] In a specific embodiment of the present invention, the Bacillus bacterial solution includes a Bacillus pasteurian bacterial solution, and the bacterial concentration of the Bacillus pasteurian bacterial solution is 1.1 to 1.6×10 10 / mL.

[0080] In a specific embodiment of the present invention, the mass ratio of the capsule core to the ethyl cellulose is 1:(1.5-2).

[0081] In a specific embodiment of the present invention, the preparation method of the semi-flexible pavement interface self-healing microcapsules is selected from one of the following methods:

[0082] Method 1 includes:

[0083] Ⅰ. The Bacillus bacterial solution is thoroughly mixed with the viscous biopolymer, urea, and calcium chloride to form a mass to obtain a capsule core mixture material;

[0084] Ⅱ. The capsule core mixed material is sheared, dried, and ground to a particle size of 50 to 100 microns to obtain spherical capsule core particles (ie, capsule core);

[0085] III. Add ethyl cellulose to the solvent, stir thoroughly (stirring speed is 400-600 r / min), and heat in a water bath (temperature is 75-80°C) until completely dissolved to obtain a capsule wall mixture;

[0086] IV. Add the capsule core to the capsule wall mixture and stir until evenly dispersed;

[0087] V. Add silane coupling agent, slowly cool down to room temperature to completely cure the microcapsules;

[0088] VI. Wash the material obtained in step V with anhydrous ethanol, filter, and dry to obtain semi-flexible pavement interface self-healing microcapsules.

[0089] Method 2 includes:

[0090] Ⅰ. The Bacillus bacterial solution is thoroughly mixed with the sticky biopolymer, urea, calcium chloride, and yeast powder to form a mass to obtain a capsule core mixture material;

[0091] Ⅱ. The capsule core mixed material is sheared, dried, and ground to a particle size of 50 to 100 microns to obtain spherical capsule core particles (ie, capsule core);

[0092] Ⅲ. Add ethyl cellulose and polyethylene to cyclohexane, stir thoroughly (stirring speed is 400-600 r / min), and heat in a water bath (temperature is 75-80 ℃) until completely dissolved to obtain a capsule wall mixture;

[0093] IV. Add the capsule core to the capsule wall mixture and stir until evenly dispersed;

[0094] V. Add silane coupling agent, slowly cool down to room temperature to completely cure the microcapsules;

[0095] VI. Wash the material obtained in step V with anhydrous ethanol, filter, and dry to obtain semi-flexible pavement interface self-healing microcapsules.

[0096] In a second aspect, the present invention provides a method for preparing the above-mentioned interface self-healing enhanced semi-flexible pavement material, comprising the following steps:

[0097] A. After hot mixing the modified porous asphalt mixture (at 180-190°C), evenly lay it at 155-170°C and let it cool;

[0098] B. When the modified porous asphalt mixture is cooled to 130°C, a modified porous asphalt mixture specimen is prepared by a wheel rolling method. When the temperature drops to 60°C, a pneumatic spray gun is used to evenly spray the semi-flexible pavement interface self-healing microcapsules into the voids of the modified porous asphalt mixture;

[0099] The road paving process also includes using a roller to compact the modified porous asphalt mixture pavement and level the joints;

[0100] D. When the surface temperature of the modified porous asphalt mixture cools to 35°C, pour cement-based grouting material, let it stand and solidify, and then maintain it to obtain an interface self-healing enhanced semi-flexible pavement material.

[0101] In a specific embodiment of the present invention, the nozzle diameter of the pneumatic spray gun is selected to be 1.0-1.5 mm, the air pressure is 0.3-0.5 MPa, the angle between the nozzle and the modified porous asphalt mixture is maintained between 45-60°, and the distance from the nozzle to the modified porous asphalt mixture is 10-20 cm. The specific parameters should be adjusted to the best effect according to the test spraying situation.

[0102] In a specific embodiment of the present invention, curing includes: curing under standard curing conditions, or natural curing after spraying water retention curing, and then heat treatment.

[0103] In a specific embodiment of the present invention, the temperature of the heating treatment (electromagnetic induction heating treatment) is 60-70° C., and the heating depth is 3-5 cm;

[0104] Before spraying the water-retaining curing agent, the relative humidity of the interface self-healing enhanced semi-flexible pavement material is adjusted to ≥80%.

[0105] A third aspect of the present invention provides a maintenance method for an interface self-healing enhanced semi-flexible pavement material, comprising the following steps:

[0106] a. When cracks initially appear on the surface of the interface self-healing enhanced semi-flexible pavement material (ie, the pavement) prepared by the above-described preparation method, dust is removed from the pavement surface using a sweeper;

[0107] b. Spray water on the road surface until the relative humidity is ≥80%. After the road surface is dry, spray a water-retaining curing agent (the purpose of spraying a water-retaining curing agent is to ensure the moisture content of the road material. If the humidity can be controlled at ≥80%, spraying a water-retaining curing agent is not necessary);

[0108] c. After 3 days of natural curing, use a pavement induction heater to heat the pavement to 60-70°C, with a heating depth of 3-5 cm;

[0109] d. When the surface temperature of the road surface cools down to 35℃, grouting treatment is carried out on the obvious cracks, and the road is rolled after being leveled. Traffic is opened after curing for 7 days (heavy-loaded vehicles are strictly prohibited from passing within 7 days of curing).

[0110] In a specific embodiment of the present invention, the coil of the road surface induction heater is a flat coil.

[0111] In a specific embodiment of the present invention, the grouting material used in the grouting treatment is a cement-based grouting material.

[0112] When cracks initially appear in a semi-flexible pavement, the composite interface fractures first, rupturing the self-healing microcapsules within the semi-flexible pavement interface. Bacillus pasteurianus, upon contact with air and water, reactivates and metabolizes to produce calcium carbonate precipitates, filling the tiny gaps. Simultaneously, heating the semi-flexible pavement to 60-70°C using a pavement induction heater enhances both the asphalt's self-healing capacity and the activity of the Bacillus spores, achieving efficient self-healing of the composite interface material and enabling repair and preventative maintenance of the semi-flexible pavement.

[0113] Unless otherwise specified, the "normal temperature" in the specific embodiments of the present invention is 25±2°C.

[0114] In the specific embodiment of the present invention, all raw materials used were purchased from the market, among which the Bacillus pasteurianus liquid (cell concentration of 1.1×10 10 The silane coupling agent was purchased from Beijing Baozang Biotechnology Co., Ltd.; KH792 from Shandong Huachen New Materials Co., Ltd.; urea was purchased from Langfang Huinuo Fine Chemical Co., Ltd.; ethyl cellulose was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; cyclohexane organic solvent was purchased from Jinan Xinwo Chemical Co., Ltd.; high-viscosity particles were purchased from Shanghai Pudong Road and Bridge Construction Co., Ltd. (RST-P type high-viscosity particles); steel wool fiber was purchased from Baoding Shengtaiyuan Metal Products Co., Ltd.; porous asphalt matrix was purchased from Sinopec Refining and Sales Co., Ltd. (70#); basalt was purchased from Jiangsu Yabang Mining Co., Ltd.; limestone was purchased from Chibi Yuanda Mining Co., Ltd.; limestone powder was purchased from Shanghai Huchang Building Materials Co., Ltd.; cement-based grouting material was purchased from Zhejiang Weihua New Building Materials Co., Ltd. (Ulike G30B); the water-retaining curing agent was Ulike protective curing agent, purchased from Zhejiang Weihua New Building Materials Co., Ltd.; yeast powder was purchased from Shandong Qilin Chemical Co., Ltd., with an effective viable bacterial count of 2×10 8 CFU / g.

[0115] All “parts” described in the following examples are “parts by mass”.

[0116] Example 1

[0117] A method for preparing an interface self-healing enhanced semi-flexible pavement material:

[0118] (1) A method for preparing semi-flexible pavement interface self-healing microcapsules, comprising the following steps:

[0119] S1. 8g of Bacillus pasteurianus liquid (cell concentration of 1.1×10 10 / mL), 3g yeast powder, 1.5g xanthan gum powder, 2.5g urea powder, and 5g calcium chloride powder were fully mixed and stirred to form a mass to obtain a capsule core mixture material;

[0120] S2. The capsule core mixture obtained in step S1 is sheared, then dried at 37°C for 16 hours, and appropriately ground to obtain spherical capsule core particles (ie, capsule cores) having a particle size of 50 to 100 microns;

[0121] S3. Add 25 g of ethyl cellulose and 6 g of polyethylene (number average molecular weight of 18,000 g / mol; weight average molecular weight of 99,800 g / mol) to 1,000 g of cyclohexane organic solvent to obtain a mixed solution, stir thoroughly at a speed of 500 r / min, and heat in a water bath (temperature of 80°C) until completely dissolved to obtain a capsule wall mixed material; weigh dry spherical capsule core particles at a mass ratio of 1:1.5 between the ethyl cellulose in the capsule core and the capsule wall, and add them to the capsule wall mixed material, stirring until the particles are evenly dispersed; add 20 g of silane coupling agent, slowly cool down, and cool to room temperature to completely solidify the microcapsules; wash the microcapsules with anhydrous ethanol, filter, and dry to obtain semi-flexible pavement interface self-healing microcapsules.

[0122] (2) Preparation method of interface self-healing enhanced semi-flexible pavement material:

[0123] S1. 10 parts of porous asphalt matrix (the porosity of the porous asphalt matrix is ​​25% and the connected porosity is 21%) are heated to liquid at 180°C, and steel wool fibers and high-viscosity particles are preheated at 150°C; 0.3 parts of steel wool fibers and 2 parts of high-viscosity particles are added to the porous asphalt matrix and stirred at 250 r / min at 180°C to fully swell the particles; high-speed shearing is performed at a speed of 4000 r / min for 30 minutes to ensure that the steel wool fibers (the length of the steel wool is 6.5 mm and the diameter is 8.89-12.7 μm), high-viscosity particles and the porous asphalt matrix are evenly mixed to obtain the modified multi-layered asphalt matrix. preheating 40 parts of coarse aggregate (basalt, particle size of 4.75-13.2 nm), 5 parts of fine aggregate (limestone, particle size less than 2.36 mm), 4 parts of filler (limestone powder, particle size range of 0.15 mm with a pass rate greater than 90%, 0.075 mm with a pass rate greater than 75%), and modified porous asphalt at 150°C; setting the temperature of the mixing pot to 180°C and the speed to 80 r / min, stirring the coarse aggregate and fine aggregate in the mixing pot for 30 seconds, then adding the modified porous asphalt and stirring for 60 seconds, and finally adding the filler and stirring for 60 seconds to obtain a hot-mix modified porous asphalt mixture;

[0124] S2. Weigh 8 parts of hot-mix modified porous asphalt mixture and pour them evenly into a mold measuring 100 mm × 100 mm × 100 mm at 170°C. When the hot-mix modified porous asphalt mixture cools to 130°C, a modified porous asphalt mixture specimen is prepared by wheel rolling. When the temperature drops to 60°C, use a pneumatic spray gun (the nozzle diameter of the pneumatic spray gun is selected to be 1.0 mm, the air pressure is 0.3 MPa, the angle between the nozzle and the modified porous asphalt mixture is maintained at 45°, and the distance between the nozzle and the modified porous asphalt mixture is 10 cm) to evenly spray 0.1 parts of semi-flexible pavement interface self-healing microcapsules into the voids of the modified porous asphalt mixture to prepare a modified porous asphalt mixture specimen (cube specimen, measuring 100 mm × 100 mm × 100 mm).

[0125] S3. After the cube specimen has cooled to room temperature, wrap the bottom and sides of the specimen with PET plastic film. Place the specimen on a vibration table and pour three parts of cement-based grouting material into the specimen from the upper surface, using the vibration table to assist in grouting, until the cement-based grouting material no longer seeps into the specimen. Clean any excess cement-based grouting material from the surface of the specimen and place the specimen in a standard curing chamber at 20°C ± 1°C and a relative humidity of ≥ 80% for curing, thereby obtaining an interface self-healing enhanced semi-flexible pavement material.

[0126] Among them, the preparation method of cement-based grouting material is: take a certain proportion of cement-based grouting material powder and mix it with water, stir it at a speed of 2500rmp for 2 minutes, the mixing temperature is 25℃, and the water-cement ratio is 0.30.

[0127] Comparative Example 1

[0128] The same as Example 1, except that the semi-flexible pavement interface self-healing microcapsules are not added.

[0129] Comparative Example 2

[0130] The same as Example 1, except that the Bacillus pasteurianus liquid in the semi-flexible pavement interface self-healing microcapsules is replaced with water of equal mass.

[0131] Comparative Example 3

[0132] The same as Example 1, except that the xanthan gum powder in the semi-flexible pavement interface self-healing microcapsules is replaced with an equal mass of Tween-80.

[0133] Comparative Example 4

[0134] The same as Example 1, except that steel wool fibers and high-viscosity particles are not added during the preparation of the interface self-healing enhanced semi-flexible pavement material.

[0135] Comparative Example 5

[0136] The same as Example 1, except that the preparation method of the interface self-healing enhanced semi-flexible pavement material is as follows:

[0137] S1. Preheat 40 parts coarse aggregate, 5 parts fine aggregate, 4 parts filler, and modified porous asphalt (prepared with 10 parts porous asphalt matrix, 0.3 parts steel wool fiber, and 2 parts high-viscosity particles) at 150°C. Set the temperature of the mixing pot to 180°C and the speed to 80 r / min. Stir the coarse aggregate and fine aggregate in the mixing pot for 30 seconds. Then, add the modified porous asphalt and stir for 60 seconds. Finally, add the filler and stir for 60 seconds to obtain a hot-mix modified porous asphalt mixture.

[0138] S2. Mix a certain proportion of cement-based grouting material powder with water and stir at 2500 rpm for 2 minutes at a mixing temperature of 25°C and a water-cement ratio of 0.30. Add 3% of the semi-flexible pavement interface self-healing microcapsules (3% by weight of the cement-based grouting material) to the cement-based grouting material and mix thoroughly to obtain a self-healing cement-based grouting material.

[0139] S3. Weigh 8 parts of hot-mix modified porous asphalt mixture and pour them evenly into a mold with dimensions of 100mm×100mm×100mm; when the hot-mix modified porous asphalt mixture is cooled to 130°C, a modified porous asphalt mixture specimen is made by a wheel rolling method; after the cube specimen is cooled to room temperature, the bottom and sides of the specimen are wrapped with PET plastic film; the specimen is placed on a vibration table, and 3 parts of self-healing cement-based grouting material is poured into the specimen from the upper surface, and the vibration table is used to assist the grouting until the grouting material no longer penetrates into the specimen; the excess self-healing cement-based grouting material on the surface of the specimen is cleaned, and the specimen is placed in a standard curing box at 20°C±1°C and a relative humidity ≥80% for curing to obtain an interface self-healing enhanced semi-flexible pavement material.

[0140] Effect Example 1

[0141] (1) The interface self-healing enhanced semi-flexible pavement material specimens prepared in Example 1 and Comparative Examples 1 to 5 were cured for 28 days and subjected to mechanical property tests in accordance with the "Standard for Test Methods for Physical and Mechanical Properties of Concrete" (GB / T50081-2019). The specific test results are shown in Table 1.

[0142] Table 1 Mechanical properties test results

[0143] Group Compressive strength (MPa) Example 1 11.7 Comparative Example 1 8.9 Comparative Example 2 10.1 Comparative Example 3 10.2 Comparative Example 4 7.3 Comparative Example 5 9.5

[0144] It can be seen from Table 1 that under the synergistic effect of steel wool fibers, high-viscosity particles and semi-flexible pavement interface self-healing microcapsules, the mechanical properties of the interface self-healing enhanced semi-flexible pavement material specimens are significantly enhanced.

[0145] (2) The interface self-healing enhanced semi-flexible pavement material specimens prepared in Example 1 and Comparative Examples 1 to 5 were cured for 28 days. Each group of 20 specimens (size 100mm×100mm×100mm) were cured and divided into a test group and a reference group. 10 specimens were selected from each group as the test group, and 70% of the load corresponding to the compressive strength in Table 1 was set as the load damage pressure value. Loads were applied to the 10 specimens in the test group respectively. After reaching the set load damage pressure value, constant load was applied for 30s, and then placed under curing conditions 1 and curing conditions 2 for 28 days on average. When the test specimens in the test group reached the curing age, their compressive strength was tested, and the average value was calculated to obtain the compressive strength F1 of the test specimens. The 10 specimens in the reference group were placed under curing conditions 1 and curing conditions 2 for 28 days on average. When the test specimens in the reference group reached the curing age, their compressive strength was tested, and the average value was calculated to obtain the compressive strength F2 of the reference specimens. Among them, the ratio of F1 and F2 is the self-healing index R of the experiment h ,Right now The specific test results are shown in Table 2.

[0146] Among them, curing condition 1 is to simulate the ordinary outdoor environment and place it in a standard curing box with a temperature of 20℃±1℃ and a relative humidity of 80% for curing; curing condition 2 is to place it in a standard curing box with a temperature of 20℃±1℃ and a relative humidity of ≥80% for curing, and perform electromagnetic induction heating (heating to 60-70℃, heating depth of 3-5cm) on the specimen once every 7 days.

[0147] Table 2 Self-healing performance test results

[0148]

[0149] As can be seen from Table 2, the mechanical properties and self-healing properties of the interface self-healing enhanced semi-flexible pavement material prepared in Example 1 of the present invention are better than those of Comparative Examples 1 to 5, and the self-healing property of Curing Method 2 is better than that of Curing Method 1. Specifically, after the specimen is loaded, the semi-flexible pavement interface self-healing microcapsules rupture under stress and release Bacillus pasteurianus and xanthan gum. The urease activity of Bacillus pasteurianus increases rapidly under high temperature, and the urease activity of Bacillus pasteurianus increases rapidly under the adsorption of Ca by xanthan gum. 2+ The synergistic effects of the xanthan gum and electromagnetic induction heating significantly enhance the efficiency of microbial-induced carbonate precipitation, filling tiny cracks. Simultaneously, the physical properties of the xanthan gum and high-viscosity particles, along with the induction heating of the steel wool fibers, enhance the local viscosity and fluidity of the asphalt, thereby strengthening the asphalt's self-healing ability and achieving dual-material synergistic self-healing for a semi-flexible pavement material.

[0150] Further comparison of the performance differences between the examples and the comparative examples shows that the comparative example 1 does not add the semi-flexible pavement interface self-healing microcapsules, and the comparative example 2 does not add the Bacillus pasteurianus liquid. Both examples cannot induce calcium carbonate precipitation to fill the gaps through the MICP action, and the self-healing performance is poor. The comparative example 3 uses Tween-80 instead of xanthan gum, and cannot absorb Ca 2+ The microbial cementation is promoted, and Tween-80 is soluble in most solvents, resulting in high losses in the preparation of microcapsules. Comparative Example 4 does not incorporate steel wool fibers and highly viscous particles, and cannot enhance the material's self-healing ability through electromagnetic induction heating and viscosity, and cannot effectively fix the interface microcapsules, resulting in easy aggregation of microcapsules and poor self-healing effect. Comparative Example 5 does not use the jet injection method to inject the interface self-healing microcapsules into the interface area, resulting in only a small number of semi-flexible pavement interface self-healing microcapsules contacting the composite interface. When the composite interface cracks, it cannot be effectively repaired, resulting in poor self-healing effect. A comprehensive comparison of the embodiments and the comparative examples shows that the embodiments have high mechanical properties and high self-healing performance, and the composite interface has strong bonding properties and good self-healing performance.

[0151] Schematic diagram of the working principle of the interface self-healing enhanced semi-flexible pavement material Figure 1 , Figure 1 (a) is before repair (with cracks), and (b) is during repair; in (a), 1 is modified porous asphalt, 2 is semi-flexible pavement interface self-healing microcapsule, 3 is aggregate, and 4 is cement-based grouting material; in (b), 1 is modified porous asphalt, 2 is semi-flexible pavement interface self-healing microcapsule, 3 is aggregate, 4 is cement-based grouting material, and 5 is calcium carbonate precipitation.

[0152] Example 2

[0153] A maintenance method for interface self-healing enhanced semi-flexible pavement material:

[0154] (1) When cracks initially appear on the surface of the interface self-healing enhanced semi-flexible pavement material (i.e., the pavement), a sweeper is used to clean the dust on the pavement surface.

[0155] (2) Spray water on the road surface until the relative humidity of the road surface is ≥80%, and spray water-retaining curing agent after the road surface is dry.

[0156] (3) After 3 days of natural curing, the pavement is heated to 60-70°C using a pavement induction heater (the coil of the pavement induction heater is a flat coil) with a heating depth of 3-5 cm.

[0157] (4) When the surface temperature of the road surface cools down to 35℃, grouting treatment is carried out on the obvious cracks (the grouting material is cement-based grouting material), and the road is rolled after being leveled. After natural curing for 7 days (heavy-loaded vehicles are strictly prohibited from passing during the curing period), traffic is opened.

[0158] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. An interface self-healing enhanced semi-flexible pavement material, characterized in that: It includes cement-based grouting material and the following raw materials in parts by weight: 7-8 parts of modified porous asphalt mixture and 0.05-0.1 parts of semi-flexible pavement interface self-healing microcapsules; The modified porous asphalt mixture comprises the following raw materials in parts by weight: 10-20 parts of porous asphalt matrix, 48-62 parts of aggregate, 2.0-2.5 parts of high-viscosity particles, and 0.3-0.5 parts of steel wool fiber; The semi-flexible pavement interface self-healing microcapsule is composed of a capsule core and a capsule wall; The capsule core comprises the following raw materials in parts by weight: 8 to 15 parts of Bacillus bacterial liquid, 1.0 to 1.5 parts of adhesive biopolymer, 2.0 to 2.5 parts of urea, and 4 to 5 parts of calcium chloride; The raw material of the capsule wall includes ethyl cellulose.

2. The interface self-healing enhanced semi-flexible pavement material according to claim 1, characterized in that: The steel wool fiber has a length of 6.5 mm and a diameter of 8.89-12.7 μm; And / or, the porous asphalt matrix has a porosity of 25-35% and a connected porosity of 18-28%.

3. The interface self-healing enhanced semi-flexible pavement material according to claim 2, characterized in that: The preparation method of the modified porous asphalt mixture comprises the following steps: After melting the porous asphalt matrix, steel wool fibers and high-viscosity particles are added, heated and stirred to swell, and then sheared at high speed to obtain modified porous asphalt; The aggregate and the modified porous asphalt are heated and mixed evenly to obtain the modified porous asphalt mixture.

4. The interface self-healing enhanced semi-flexible pavement material according to claim 1, characterized in that: The adhesive biopolymer includes at least one of xanthan gum, gum arabic, guar gum and carrageenan; And / or, the capsule core is granular with a particle size of 50 to 100 microns.

5. The interface self-healing enhanced semi-flexible pavement material according to claim 1, characterized in that: The bacterial concentration of the Bacillus spore liquid is 1.1~1.6×10 10 pieces / mL.

6. The interface self-healing enhanced semi-flexible pavement material according to claim 1, characterized in that: The mass ratio of the capsule core to the ethyl cellulose is 1:(1.5-2).

7. The interface self-healing enhanced semi-flexible pavement material according to claim 1, characterized in that: The preparation method of the semi-flexible pavement interface self-healing microcapsules comprises the following steps: The bacillus liquid is mixed with a sticky biopolymer, urea and calcium chloride to form a mass to obtain a capsule core; The semi-flexible pavement interface self-healing microcapsules are obtained by adding ethyl cellulose into a solvent, heating and dissolving the cellulose, adding a capsule core and a silane coupling agent, mixing the mixture evenly, and cooling and solidifying the mixture.

8. A method for preparing the interface self-healing enhanced semi-flexible pavement material according to any one of claims 1 to 7, characterized in that: The following steps are involved: The modified porous asphalt mixture is hot-mixed and evenly paved, and then the semi-flexible pavement interface self-healing microcapsules are placed in the gaps of the modified porous asphalt mixture. After cooling, cement-based grouting material is poured, solidified, and maintained to obtain the interface self-healing enhanced semi-flexible pavement material.

9. The preparation method according to claim 8, characterized in that The curing includes: curing under standard curing conditions, or natural curing after spraying water retention curing, and then heating treatment.

10. A maintenance method for interface self-healing enhanced semi-flexible pavement material, characterized in that: The following steps are involved: When cracks initially appear on the surface of the interface self-healing enhanced semi-flexible pavement material according to any one of claims 1 to 7, a water-retaining curing agent is sprayed on the surface, the material is naturally cured and then subjected to heating treatment, grouting treatment is performed after cooling, and the material is smoothed and then rolled.

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