Composite slurry seal with bionic scale structure waterproof layer and preparation method thereof

Abstract

This application relates to the field of road engineering materials technology, and discloses a composite slurry seal with a biomimetic scale-structured waterproof layer and its preparation method. The seal includes a two-layer composite structure comprising a waterproof functional layer, an interlayer bonding layer, and an abrasion functional layer. The waterproof layer raw materials include surface-activated modified PET aggregate, thixotropic modified emulsified asphalt containing a rheology modifier, and active fillers. The preparation method covers PET surface modification, thixotropic system construction, interlayer bonding during a specific window period, and layered paving processes. This invention solves the problem of upward buoyancy and layering by introducing a rheology modifier to construct a thixotropic network, utilizing yield stress to balance buoyancy, restricting the vertical migration of lightweight PET aggregate, and promoting its orderly layered arrangement. Surface chemical modification transforms the physical interface into chemical bonding, significantly improving interfacial bonding strength. Combined with a flexible-at-the-bottom, rigid-at-the-top structural design, it significantly improves the seal's waterproof sealing, crack resistance, durability, and shear stability.

Description

Technical Field

[0001] This invention relates to the field of road engineering materials technology, specifically to a composite slurry seal with a biomimetic scale-structured waterproof layer and its preparation method. Background Technology

[0002] Slurry seal is a cold-mix asphalt mixture technology widely used in preventative road maintenance. It is mainly composed of appropriately graded mineral aggregates, emulsified asphalt, water, fillers, and necessary additives mixed in a specific ratio. In its mixed state, the mixture is a slurry-like flow. It is evenly spread onto the existing road surface using specialized machinery. After demulsification, water separation, evaporation, and curing, it firmly bonds to the original road surface, forming a thin, dense treatment layer. As a mainstream technology for treating early-stage pavement damage, slurry seal effectively seals micro-cracks, restores surface smoothness and skid resistance, and prevents water infiltration, thus protecting the base course. It is a key means to delay pavement performance degradation and reduce the overall life-cycle maintenance cost.

[0003] According to Chinese Patent Publication No. CN114477877B, this patent describes a high-plasticity modified slurry seal road material and its preparation method. Addressing the adhesion problem caused by the smooth, non-absorbent surface of modified road water-stabilized layers containing industrial solid waste such as phosphogypsum, this patent designs a cement-based composite seal material. The technical solution uses quartz sand as the sole aggregate, constructing a gelling system through cement, phenolic resin adhesive, and a complex formula curing agent (containing multiple components such as gelling agent, sodium silicate, and magnesium oxide). Hydroxymethyl cellulose is added to improve plasticity. Its core advantage lies in enhancing adhesion and structural strength to industrial solid waste water-stabilized layers. Publicly available performance data shows a strength of 15-25 MPa, with superior impermeability compared to conventional seals. However, this technology has significant inherent limitations, making it unsuitable for preventative maintenance of conventional asphalt pavements: First, its single-layer structure design lacks functional layering optimization. The high elastic modulus of the cement-based system results in a "strong but brittle" material, unable to absorb stress generated by reflective cracking in the base layer, making it prone to cracking and damage after long-term service. One of the core requirements of preventative maintenance for conventional asphalt pavements is resistance to reflective cracking. Second, its preparation process relies on high temperatures, requiring water to be heated to 100°C to dissolve hydroxymethyl cellulose. The preparation of the curing agent requires high-pressure heating at 120°C and multi-stage cooling reactions, resulting in high energy consumption and incompatibility with the on-site requirements of "rapid construction and short maintenance period" for conventional asphalt pavements. Third, this system does not contain emulsified asphalt, making it a typical... The cement-resin composite cementitious system has a significantly different coefficient of thermal expansion from that of asphalt pavement base layers, which can easily lead to interlayer delamination after long-term temperature cycling, resulting in insufficient compatibility. Fourth, this technology does not involve rheological control design. If applied to lightweight aggregates (such as PET), the lack of yield stress to balance buoyancy will cause the aggregates to float and segregate, making it impossible to form a continuous functional layer. Furthermore, the quartz sand is not surface-modified and relies solely on physical accumulation to bond with the cementitious system, which still poses a risk of interface delamination after long-term exposure to water. Fifth, the functional positioning of this technology focuses on bond-strength and does not consider the anti-skid performance required by conventional asphalt pavements. The gradation design of the quartz sand is not optimized for anti-skid requirements, and its applicable scenarios are strictly limited to industrial solid waste water stabilization layers, making it unsuitable for preventive maintenance of conventional asphalt pavements.

[0004] In addition to the aforementioned patents, other existing slurry seal technologies also share similar common problems: some technologies attempt to incorporate crushed PET waste as aggregate into the seal, but fail to perform surface activation treatment on the PET. As an inert polyester material, PET has low surface energy and can only physically adsorb with asphalt. Under rainwater immersion or temperature cycling, the asphalt film easily peels off from the PET surface, leading to interface failure. Some layered design technologies do not have a specific process for interlayer bonding, relying solely on conventional slow-cracking emulsified asphalt as the tack coat. They fail to control the matching of the tack coat spraying timing with the curing state of the underlying layer. If the tack coat is sprayed after the underlying layer is completely hardened, it cannot penetrate; if the tack coat is sprayed before the underlying layer is dry, it will cause the underlying layer to shift, ultimately resulting in insufficient interlayer fusion. Other technologies do not introduce a rheological control mechanism. Lightweight aggregates, due to their lower density than the asphalt matrix, float and aggregate, failing to build a continuous and dense waterproof barrier. Instead, the uneven distribution of aggregates weakens the overall mechanical properties of the seal. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a composite slurry seal with a biomimetic scale-structured waterproof layer and its preparation method, which solves the problems of poor functional synergy, difficulty in simultaneously achieving anti-reflective cracking and waterproof performance, easy floating and segregation of lightweight aggregates, and weak bonding at heterogeneous interfaces in conventional slurry seals.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of this invention provides a composite slurry sealant with a biomimetic scale-structured waterproof layer, employing the following technical solution: A composite slurry sealant with a biomimetic scale-like waterproof layer is used to construct a two-layer composite structure consisting of a waterproof functional layer, an interlayer bonding layer, and an abrasion-resistant functional layer, from bottom to top. The waterproof functional layer comprises modified PET aggregate, thixotropic modified emulsified bitumen, active fillers, and water. The modified PET aggregate is a polyester sheet with an activated surface. The thixotropic modified emulsified bitumen contains rheology modifiers, and the equivalent pure bitumen content of the thixotropic modified emulsified bitumen is 8.0 to 12.0 parts per part (based on the dry weight of the modified PET aggregate). The interlayer bonding layer is made of diluted slow-cracking emulsified bitumen. The abrasion-resistant functional layer comprises mineral aggregate, emulsified bitumen, and fillers.

[0007] By adopting the above technical solution, this invention achieves the following technical effects by combining functional hierarchical design with rheological control: To address the issue that the density of PET material (approximately 1.38 g / cm³) is significantly lower than that of conventional asphalt mortar matrix, this invention introduces a rheology modifier into emulsified asphalt to construct a thixotropic system. This system forms a structural network with a certain yield stress under static conditions. When the yield stress exceeds the net buoyancy shear stress experienced by the PET sheet in the matrix, it can restrict the vertical migration of the PET sheet. This characteristic causes the sheet-like PET to arrange itself in a stacked, inverted manner under gravity, forming a dense and ordered physical water-blocking structure, thus solving the problem of waterproofing failure caused by the stratification of lightweight aggregates.

[0008] By surface-activating PET aggregates (such as silane grafting or plasma oxidation), hydroxyl, carboxyl, or organic functional groups are introduced onto the surface of the inert polyester. These active groups chemically crosslink or form hydrogen bonds with the active components in the modified emulsified asphalt, transforming the interface, which was originally dominated by physical adsorption, into an interface with chemical bonding forces, thereby improving the asphalt film's anti-peeling ability in a water environment.

[0009] By setting a high equivalent pure bitumen content of 8.0 to 12.0 parts per unit area, combined with the large specific surface area of ​​PET sheets, a thick bitumen coating film is formed on the aggregate surface. This thick film structure, combined with the inherent flexibility of PET material, reduces the elastic modulus of the waterproof functional layer, enabling it to absorb and dissipate reflective crack stress from the substrate, thus acting as a stress-absorbing layer.

[0010] Preferably, the modified PET aggregate is a circular sheet with a diameter of 5.5 to 6.5 mm and a thickness of 0.5 to 1.0 mm, and the surface activation treatment layer of the modified PET aggregate is a silane coupling agent graft layer or a plasma oxidation layer; the raw materials for the thixotropic modified emulsified asphalt include slow-setting fast-curing cationic emulsified asphalt, cationic styrene-butadiene latex and rheology modifier; the rheology modifier is organic modified bentonite or modified nanocellulose; based on the mass of the slow-setting fast-curing cationic emulsified asphalt, the amount of cationic styrene-butadiene latex is 3.0% to 5.0%, and the dry weight amount of the rheology modifier is 0.5% to 1.5%.

[0011] By employing the above technical solutions, organically modified bentonite or nanocellulose forms a carousel-like structure in the emulsion through edge-face electrostatic interactions or hydrogen bonding, endowing the system with significant thixotropy—shear thinning to facilitate mixing during construction and static thickening to fix the aggregate position. Simultaneously, the bifunctional structure of the silane coupling agent acts as a molecular bridge between the inorganic matrix and the organic PET, enhancing interfacial adhesion strength.

[0012] Preferably, the base material of the modified PET aggregate is a modified copolyester with a heat shrinkage initiation temperature in the range of 45 to 60 degrees Celsius; and the surface micropores of the modified PET aggregate adsorb latent curing agent components.

[0013] By employing the above technical solution, a thermosensitive self-healing and chemical release mechanism is utilized: when the road surface temperature rises to the thermal shrinkage initiation temperature range of the modified copolyester, the polymer chain segments in the oriented state undergo deorientation movement, generating micro-shrinkage stress. This shrinkage stress, on the one hand, exerts a compressive effect on the surrounding asphalt, promoting the closure of microcracks; on the other hand, it compresses the micropores on the PET surface, promoting the release and diffusion of the pre-adsorbed latent curing agent to the asphalt interface, triggering a local cross-linking reaction, and achieving in-situ repair of aged or damaged interfaces.

[0014] Preferably, the asphalt residue distribution of the diluted slow-cracking emulsified asphalt in the interlayer bonding layer is 0.3 to 0.5 kg per square meter.

[0015] By adopting the above technical solution, a continuous bonding interface is constructed between the waterproof functional layer and the wear functional layer, reducing the risk of interlayer slippage caused by the large difference in elastic modulus between the two layers, and ensuring the integrity of the composite structure under the action of horizontal shear force of traffic.

[0016] The second aspect of this invention provides a method for preparing a composite slurry seal with a biomimetic scale-structured waterproof layer, employing the following technical solution: A method for preparing a composite slurry seal with a biomimetic scale-structured waterproof layer includes the following steps: S1, preparing modified PET aggregate: surface activation treatment of PET sheets; S2, preparing thixotropic modified emulsified asphalt: adding rheology modifiers to emulsified asphalt and shear dispersion; S3, construction of the waterproof functional layer: mixing modified PET aggregate, thixotropic modified emulsified asphalt, active filler, and water to form a first mixture, which is then spread on the road surface to form a waterproof functional layer; S4, interlayer bonding treatment: spraying tack coat oil onto the surface of the waterproof functional layer when it is in a partially dry and not fully hardened state; S5, construction of the abrasion functional layer: after the tack coat oil has demulsified, spreading a second mixture of mineral aggregate, emulsified asphalt, and filler on the interlayer bonding layer, and curing it to form a double-layer composite structure.

[0017] By adopting the above technical solution, this invention establishes a time-controlled construction process for lightweight aggregates, the principle and effects of which are as follows: In the mixing and spreading stage of step S3, the high shear rate provided by mechanical stirring disrupts the structural network formed by the rheology modifier, resulting in a low-viscosity fluid state in the mixture. This ensures the encapsulation of PET aggregate and its workability in spreading. After spreading, the shear force is removed, the structural network quickly recovers, and the system viscosity rises again. This physically fixes the spatial position of the PET aggregate before the emulsion breaks down, preventing it from floating.

[0018] In step S4, the tack coat is sprayed during a specific window period when the waterproofing layer is "touch dry but not fully hardened." At this point, the surface of the waterproofing layer has sufficient strength to withstand the spraying operation, but the internal emulsified asphalt residue has not yet fully solidified. The tack coat can penetrate into the micropores of the waterproofing layer surface and undergo physical penetration and local fusion with the semi-cured asphalt matrix. Subsequently, the abrasion layer material applied in step S5 is embedded in this area. During the final curing process, these three components form a transition zone where physical anchoring and chemical fusion coexist, improving the bonding effect between the rigid and flexible layers.

[0019] As a preferred embodiment, the specific method of surface activation treatment in step S1 includes: after cleaning and drying the PET sheet, immersing it in an alcohol-water solution containing 1.5% to 3.0% silane coupling agent, adjusting the pH value to 3.5 to 4.5, soaking it at 25 to 40 degrees Celsius for 20 to 40 minutes, and then heat-curing it at 100 to 110 degrees Celsius; or, placing the PET sheet in a vacuum reaction chamber, introducing oxygen or argon gas, and performing plasma treatment at a power of 200 to 500 watts for 60 to 180 seconds.

[0020] By adopting the above technical solutions, the process parameters for both chemical grafting and physical etching pathways were clarified. The silane coupling agent method uses an alcohol-water solvent system to control the hydrolysis rate and promotes the condensation reaction to form a stable covalent bond layer during the thermal curing stage; the plasma method uses high-energy particles to bombard and break the molecular chains on the PET surface, generating polar groups in situ and increasing surface roughness. Both methods effectively improve the surface wetting tension.

[0021] As a preferred embodiment, the specific preparation process of thixotropic modified emulsified asphalt in step S2 is as follows: cationic styrene-butadiene latex is added to slow-cracking fast-setting cationic emulsified asphalt and stirred evenly, followed by the addition of pre-dispersed organic modified bentonite slurry or nanocellulose suspension, and shearing and mixing for 15 to 20 minutes using a high-shear emulsifier at a speed of 3000 to 5000 rpm.

[0022] By adopting the above technical solution, the high-shear process ensures the deagglomeration and uniform dispersion of the rheology modifier, enabling it to be fully peeled off and construct thixotropic structural units, thus avoiding local rheological failures caused by uneven dispersion.

[0023] Preferably, in step S3, the yield stress of the first mixture is greater than the net buoyancy shear stress experienced by the modified PET aggregate in the emulsion matrix; the paving thickness of the waterproof functional layer is 8 to 10 mm, and the paving thickness of the abrasion functional layer is 6 to 8 mm.

[0024] By adopting the above technical solution, the conditions for rheological control were defined from the perspective of mechanical equilibrium, ensuring the physical stability of the mixture under static conditions. The design of the thickness parameters followed the accommodating requirements of PET aggregate size and the functional allocation principle of the double-layer structure, ensuring both the continuity of the waterproof layer and controlling the total thickness.

[0025] Preferably, in step S4, the state of being partially dry but not fully hardened is when the waterproof functional layer is laid 45 to 75 minutes after application and the surface color changes from brown to black; in step S5, the abrasion functional layer is applied within 15 to 30 minutes after the tack coat demulsifies and turns black.

[0026] By adopting the above technical solution, the time window for interlayer construction was quantified. This time parameter is set based on the demulsification and strength growth law of cationic emulsified asphalt, avoiding the displacement and deformation of the lower layer caused by premature construction, and also avoiding the decrease in interlayer fusion caused by late construction. It is a process parameter that ensures the overall mechanical properties of the double-layer structure.

[0027] The present invention has the following beneficial effects: 1. This invention constructs a thixotropic system by introducing a rheology modifier into emulsified asphalt. The system's yield stress balances the buoyancy of lightweight PET aggregate in the liquid phase, effectively limiting the vertical migration of PET sheets. This mechanism causes the PET aggregate to arrange itself in an orderly, layered, and collapsed manner under gravity, forming a dense, physically waterproof structure. This solves the problem of large internal voids and impermeability failure in the waterproof layer caused by the floating and stratification of lightweight aggregate in traditional processes, significantly reducing the pavement permeability coefficient.

[0028] 2. This invention involves surface activation treatment of inert PET aggregate and interlayer bonding during a specific process window, improving the bonding state at the interface of heterogeneous materials. The polar groups introduced by surface activation transform the physical adsorption between PET and the bitumen matrix into chemical bonding. Combined with the penetration and interpenetration of the tack coat oil in a semi-cured state, a stable interfacial transition zone is constructed. This effectively improves the bitumen adhesion within the waterproof layer and the interlayer shear strength between the waterproof layer and the wear layer, preventing water damage, delamination, and interlayer slippage.

[0029] 3. This invention utilizes a dual-layer composite structure to achieve functional decoupling and synergy of the slurry seal layer. The bottom layer is a flexible PET layer with a high asphalt-aggregate ratio. The low elastic modulus and high toughness of PET material absorb and dissipate reflective crack stress from the base layer, acting as a stress-absorbing layer. The top layer uses rigid mineral aggregates to provide the anti-skid and wear-resistant properties required for driving. This combination of a flexible bottom and a rigid top structure improves the seal system's adaptability to base layer deformation without increasing the overall thickness, delays the propagation of reflective cracks, and extends the service life of preventative road maintenance. Attached Figure Description

[0030] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a schematic diagram of the composite sealing structure of the present invention. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Please see the appendix Figure 1 -Appendix Figure 2 This invention provides a composite slurry seal with a biomimetic scale structure waterproof layer and its preparation method.

[0033] raw material: Polyethylene terephthalate (PET) sheets, industrial grade semi-crystalline thermoplastic polymer, molecular formula (C 10 H8O4) n Number average molecular weight 22,000-26,000, weight average molecular weight 45,000-55,000, density 1.38 g / cm³, glass transition temperature 76℃, melting point 255℃, intrinsic viscosity 0.80-0.84 dL / g, biaxially oriented transparent sheet, thickness 0.5 mm or 1.0 mm.

[0034] The No. 70 road petroleum asphalt conforms to JTGF40-2004 standard, with a penetration of 60-80 (0.1mm) and a softening point ≥46℃; cationic styrene-butadiene latex (SBR Latex), with a solid content of 60%±1%, a bound styrene content of 23.5%, a pH value of 4.0-5.0, and a glass transition temperature of -16℃; organically modified bentonite, quaternary ammonium salt modified montmorillonite, and a layer spacing of d. 001 ≥2.2nm, montmorillonite content ≥96%.

[0035] 3-Aminopropyltriethoxysilane (KH-550), purity ≥99.0%; octadecyltrimethylammonium chloride, active ingredient content ≥98%; ordinary silicate cement, P.O42.5 grade, conforming to GB175-2007 standard; lignin fiber, ash content ≤13%, average length 3.5mm.

[0036] The basalt aggregate has a rock density of 2.85 g / cm³, a crushing value of ≤12%, a polishing value of ≥45, and its gradation meets the requirements of ES-2 type in CJJ / T66-2011. The hydrochloric acid (concentration 36%) and anhydrous ethanol (purity ≥99.7%) are both commercially available analytical grade reagents.

[0037] Preparation example: Preparation Example 1: This preparation example provides a surface-silanized modified PET aggregate, comprising the following steps: First, PET sheets with a diameter of 6 mm and a thickness of 0.5 mm are ultrasonically cleaned in a weakly alkaline washing solution for 15 minutes, rinsed three times with deionized water, and then dried in an oven at 80°C for later use. Next, a modification solution is prepared by mixing anhydrous ethanol and water at a mass ratio of 9:1, adjusting the pH to 4.0 with acetic acid, and adding 1.5% (w / w) of KH-550 silane coupling agent, followed by stirring and hydrolysis for 30 minutes. The dried PET sheets are then immersed in the above modification solution and soaked at a constant temperature of 25°C for 30 minutes. The sheets are then removed, drained, and heat-cured in an oven at 105°C for 45 minutes, and cooled to room temperature to obtain the final product. This preparation example represents the intermediate parameter conditions for the silane coupling agent modification process.

[0038] Preparation Example 2: This preparation example provides a surface-silanized modified PET aggregate, comprising the following steps: First, a PET sheet with a diameter of 6 mm and a thickness of 1.0 mm is cleaned and dried. A modification solution is prepared by mixing anhydrous ethanol and water at a mass ratio of 9:1, adjusting the pH to 3.5, and adding 3.0% (w / w) of KH-550 silane coupling agent, followed by hydrolysis for 20 minutes. The PET sheet is then immersed in the modification solution and soaked at a constant temperature of 40°C for 40 minutes. The sheet is then removed, drained, and heat-cured in a 110°C oven for 60 minutes. This preparation example represents the high-concentration, high-temperature, and long-term parameter boundary conditions of the silane coupling agent modification process.

[0039] Preparation Example 3: This preparation example provides a surface plasma-modified PET aggregate, comprising the following steps: A cleaned and dried PET sheet is laid flat in a vacuum plasma treatment chamber, and a vacuum is drawn until the back pressure is less than 10 Pa. High-purity oxygen is introduced as the working gas, with the gas flow rate controlled at 100 sccm. The radio frequency power supply is turned on, the discharge power is set to 300 W, and the treatment time is 120 seconds, causing an oxidation reaction on the PET surface to generate polar groups. After treatment, the pressure is restored to normal and the aggregate is removed. This preparation example serves to support the generalization of the plasma physical modification method in the claims.

[0040] Preparation Example 4: This preparation example provides a modified polyester aggregate (PETG) with low-temperature heat shrinkage properties, comprising the following steps: selecting PETG chips with a glass transition temperature of 50°C, and processing them into circular sheets with a diameter of 6 mm and a thickness of 0.5 mm. Following the steps described in Preparation Example 1, surface silanization treatment is performed on the PETG using a 2.0% concentration of KH-550 modifying liquid, wherein the heat curing temperature is adjusted to 60°C to avoid material deformation, and the curing time is extended to 90 minutes. This preparation example is used to support a special embodiment with heat-sensitive self-healing function.

[0041] Preparation Example 5: This preparation example provides a thixotropic modified emulsified asphalt, comprising the following steps: heating No. 70 road petroleum asphalt to 140°C to make it fluid; adding an aqueous solution of octadecyltrimethylammonium chloride emulsifier at 1.2% of the asphalt mass; emulsifying by a colloid mill to obtain cationic emulsified asphalt with a solid content of 60%; and cooling to 60°C. Slowly adding cationic styrene-butadiene latex at 3.0% of the emulsified asphalt mass, and stirring at low speed for 10 minutes. Pre-dispersing organic modified bentonite in water to prepare a slurry, and adding it to the above modified emulsified asphalt at a ratio of 1.0% of the dry weight of the organic modified bentonite to the mass of the emulsified asphalt. Starting a high-shear emulsifier, shearing and dispersing at 4000 rpm for 15 minutes until the system forms a thixotropic structure. This preparation example represents a medium dosage parameter for rheology modifiers.

[0042] Preparation Example 6: This preparation example provides a thixotropic modified emulsified asphalt, comprising the following steps: preparing a base cationic emulsified asphalt and cooling it to 55°C. Adding 5.0% (by weight) of cationic styrene-butadiene latex to the emulsified asphalt. Adding pre-dispersed bentonite slurry to the system at a ratio of 1.5% (by dry weight) of organically modified bentonite to the emulsified asphalt. Starting a high-shear emulsifier and shearing and dispersing at 5000 rpm for 20 minutes. This preparation example represents the boundary of high rheology modifier dosage and high shear energy parameters.

[0043] Preparation Example 7: This preparation example provides a thixotropic modified emulsified asphalt, comprising the following steps: preparing a basic cationic emulsified asphalt and cooling it to 60°C. Adding 4.0% (by weight) of cationic styrene-butadiene latex to the emulsified asphalt. Selecting modified nanocellulose as a rheology modifier, preparing it into a suspension and adding it to the system, the dry weight of the nanocellulose being 0.8% (by weight) of the emulsified asphalt. Shearing and mixing at 3000 rpm for 20 minutes. This preparation example is intended to support the generalization regarding different types of rheology modifiers in the claims.

[0044] Preparation Example 8: This preparation example provides a modified emulsified asphalt without added rheology modifiers, comprising the following steps: emulsifying No. 70 road petroleum asphalt to obtain cationic emulsified asphalt, and cooling it to 60°C. Adding 4.0% (by weight) of cationic styrene-butadiene latex to the emulsified asphalt, and mixing thoroughly using a conventional mixer at 300 rpm, without adding organic modified bentonite or nanocellulose, and without high-shear treatment. This preparation example will be used as the binder in the comparative example.

[0045] Example: Example 1: This example provides a biomimetic flake-like PET double-layer composite slurry seal, the preparation and construction process of which includes the following steps: Step 1, Mixture preparation: Select the surface silanized modified PET aggregate (6mm in diameter, 0.5mm in thickness) obtained in Preparation Example 1 as the first layer aggregate. Mix the PET aggregate with the thixotropic modified emulsified asphalt, ordinary silicate cement, lignin fiber and water obtained in Preparation Example 5. Based on 100 parts of the dry weight of PET aggregate, the amount of thixotropic modified emulsified asphalt is added at an asphalt-aggregate ratio of 10.0% after conversion to pure asphalt, the amount of cement is 1.5 parts, the amount of lignin fiber is 0.2 parts, and 2.0 parts of water are added. Step 2, Waterproof layer paving: Spread the above mixture on a clean road surface using a slurry sealer, setting the paving box thickness to 9mm. During mechanical mixing and paving, the mixture remains fluid; after paving and leveling, the thixotropic emulsion locks the position of the PET aggregate, making it arranged in a layered manner. Step 3, Interlayer Treatment: 60 minutes after the first layer is laid, when the waterproof layer turns black and the surface is touch dry, spray diluted SS-1h emulsified asphalt as a tack coat at a rate of 0.4 kg / m² (based on asphalt residue). Step 4, Wearing Course Laying: 20 minutes after the tack coat is sprayed, lay the second traditional wearing course. The second course uses ES-2 graded basalt aggregate and conventional CSS-1h emulsified asphalt, with an asphalt-aggregate ratio of 7.5% and a laying thickness of 6 mm. After both layers are laid, allow them to cure naturally.

[0046] Example 2: This example provides a biomimetic flake-like PET double-layer composite slurry seal, employing a high asphalt-aggregate ratio and large thickness design parameters, including the following steps: Step 1, Mixture preparation: Select the surface-silanized modified PET aggregate (6mm diameter, 1.0mm thickness) obtained in Example 2 as the first layer aggregate. Mix this PET aggregate with the high-shear thixotropic modified emulsified asphalt obtained in Example 6. Based on 100 parts of dry weight of PET aggregate, the modified emulsified asphalt is added at an asphalt-aggregate ratio of 12.0% after conversion to pure asphalt, the cement is added at 2.0 parts, the lignin fiber is added at 0.3 parts, and 1.5 parts of water are added. Step 2, Waterproof layer paving: Pave the mixture onto the road surface, setting the paving thickness to 10mm. Step 3, Interlayer treatment: 45 minutes after the first layer is paved, once the waterproof layer has demulsified and formed, spray tack coat at a rate of 0.5kg / m². Step 4, Wear Layer Laying: The second layer is laid 15 minutes after the tack coat demulsifies. The second layer uses ES-3 graded basalt aggregate, with an asphalt-aggregate ratio of 8.5% and a laying thickness of 8mm. Curing is then performed after completion.

[0047] Example 3: This example provides a biomimetic flake-like PET double-layer composite slurry seal, employing a low asphalt-aggregate ratio and thin-layer design parameters, and utilizing plasma-modified materials and a nanocellulose rheological system. The steps include: Step 1, Mixture Preparation: The plasma-modified PET aggregate obtained in Example 3 is selected as the first layer aggregate. This PET aggregate is mixed with the nanocellulose-modified emulsified asphalt obtained in Example 7. Based on 100 parts of dry weight of PET aggregate, the modified emulsified asphalt is added at an asphalt-aggregate ratio of 8.0% (converted to pure asphalt), cement is added at 1.0 part, lignin fiber at 0.1 part, and water at 2.5 parts. Step 2, Waterproofing Layer Laying: The mixture is laid on the road surface, with a laying thickness of 8 mm. Step 3, Interlayer Treatment: 75 minutes after the first layer is laid, when the waterproofing layer meets the interlayer construction requirements, a tack coat is sprayed at a rate of 0.3 kg / m². Step 4, Wear Layer Laying: The second layer is laid 30 minutes after the tack coat demulsifies. The second layer uses ES-2 graded basalt aggregate, with an asphalt-aggregate ratio of 6.5% and a laying thickness of 6mm. Curing is then performed after completion.

[0048] Example 4: This example provides a biomimetic scaly PET double-layer composite slurry seal with heat-sensitive self-healing potential, comprising the following steps: Step 1, Mixture preparation: The low-temperature heat-shrinkable modified polyester (PETG) aggregate obtained in Example 4 is selected as the first layer aggregate. This aggregate is mixed with the thixotropic modified emulsified asphalt obtained in Example 5. Based on 100 parts dry weight of PETG aggregate, the asphalt-aggregate ratio is set at 10.0%, the cement addition is 1.5 parts, the lignin fiber addition is 0.2 parts, and 2.0 parts water is added. Step 2, Waterproofing layer paving: The mixture is paved on the road surface, with a paving thickness of 8 mm. Step 3, Interlayer treatment: Tack coat is sprayed 60 minutes after the first layer is paved, with a spraying amount of 0.4 kg / m². Step 4, Wearing layer paving: The second layer is paved 25 minutes after the tack coat demulsifies. The second layer uses ES-2 type graded aggregate, with an asphalt-aggregate ratio of 7.0% and a paving thickness of 6 mm. During the maintenance period, the ambient temperature should be kept above 25℃, and heavy-load vehicles should avoid sudden braking in the early stage of operation.

[0049] Comparative example: Comparative Example 1: Compared with Example 1, the difference is that the modified PET aggregate in the first layer (waterproof functional layer) is replaced with an equal volume of conventional fine-grained limestone crushed stone (particle size 3-5mm), and the emulsified asphalt used in the first layer is conventional modified emulsified asphalt without rheology modifier. The other raw material ratios, construction steps and curing conditions are the same.

[0050] Comparative Example 2: Compared with Example 1, the difference is that the PET aggregate used in the first layer was not subjected to any chemical grafting or plasma surface activation treatment (commercially available clean PET sheets were used directly), and the rest were the same.

[0051] Comparative Example 3: Compared with Example 1, the difference is that the emulsified asphalt used in the first layer was replaced with ordinary modified emulsified asphalt (i.e., non-thixotropic) without added organic modified bentonite or nanocellulose obtained in Preparation Example 8, and the rest were the same.

[0052] Comparative Example 4: Compared with Example 1, the difference is that the layered paving process was eliminated. The modified PET aggregate of the first layer and the basalt aggregate of the second layer in Example 1 were mixed at a volume ratio of 1:1, and conventional modified emulsified asphalt was used for single-layer paving with a paving thickness of 15 mm. All other aspects were the same.

[0053] Comparative Example 5: Compared with Example 1, the difference is that the interlayer treatment process in step three was omitted, that is, the second wear layer was laid directly after the first layer was laid, and no tack coat was sprayed. Everything else was the same.

[0054] Comparative Example 6: Compared with Example 4, the difference is that the first layer of aggregate was replaced by the low-temperature heat-shrinkable modified polyester (PETG) obtained in Preparation Example 4 with the ordinary modified PET aggregate (non-heat-sensitive type) obtained in Preparation Example 1, and the rest were the same.

[0055] Test example: Test Example 1: To simulate the static state after paving and detect differences in component distribution in the vertical direction, the fresh mixtures prepared in each example and comparative example were immediately poured into a 1000mL transparent glass graduated cylinder, with the filling height controlled at 250mm ± 5mm. The graduated cylinder was placed on a horizontal test bench and allowed to stand for 20 minutes at room temperature (25℃) to correspond to the window period from paving to initial setting in actual construction. After standing, the upper 1 / 3 and lower 1 / 3 volumes of the mixture were respectively sampled and labeled as the upper layer sample and the lower layer sample. The upper and lower layer samples were washed and dried, and the aggregate mass was separated and weighed, denoted as W. top and W bottom According to the formula SD= W top -W bottom / (W top +W bottom Calculate the degree of segregation (SD) by multiplying the result by 100%. The closer the value is to 0, the more homogeneous the system is. The larger the value is, the more severe the segregation is.

[0056] The aggregate-asphalt adhesion test was conducted according to the T0616 test method for adhesion between asphalt and coarse aggregate in JTGE20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". Aggregates, whether pretreated or untreated, were coated with emulsified asphalt from the corresponding examples or comparative examples. After curing, the samples were suspended in gently boiling water for 3 minutes. The samples were then removed and the asphalt film peeling was observed, and evaluated from Grade 1 (complete peeling) to Grade 5 (virtually no peeling).

[0057] Table 1 Results of anti-segregation stability and adhesion tests for each group of mixtures

[0058] Conclusions and Mechanism Analysis: Based on the data in Table 1 and the design mechanism of the technical solution, the analysis is as follows: Comparing the data from Examples 1 to 4 with Comparative Example 3, it is evident that the rheology modifier is crucial for achieving uniform distribution of PET aggregate. Comparative Example 3, without the addition of organically modified bentonite or nanocellulose, achieved a segregation degree of 42.7%. Because the density of PET (1.38 g / cm³) is lower than that of the emulsion matrix, it migrates upwards under buoyancy during settling, resulting in the enrichment of unbonded PET sheets on the surface of the paving layer and the enrichment of asphalt at the bottom, failing to form an effective structure. The segregation degree in Examples 1 to 4 was controlled between 1.8% and 3.1%, indicating that the yield stress system constructed by the rheology modifier balanced the net buoyancy of the PET particles; after shearing ceased, the matrix viscosity recovered, limiting the vertical movement of the dispersed phase and ensuring the physical stability of the mixture before demulsification.

[0059] Comparative data from Example 1 and Comparative Example 2 confirmed the necessity of surface pretreatment. In Comparative Example 2, the untreated PET had an adhesion grade of 1. The PET molecular chains lacked polar groups, resulting in low surface energy and only physical adsorption with asphalt. Water molecules easily displaced the asphalt film, leading to peeling. Example 1 (silane coupling) and Example 3 (plasma) both achieved an adhesion grade of 5. The silane coupling agent reacted with the hydroxyl or carboxyl groups on the PET surface and crosslinked with the active components of the asphalt. Plasma treatment introduced oxygen-containing polar groups, transforming the hydrophobic interface into a water-resistant, oleophilic interface.

[0060] Although Comparative Example 1 met the adhesion requirements, the high density of the aggregate resulted in a segregation rate of 38.4% (manifested as settling), confirming that traditional fluid systems are ineffective in stabilizing suspended aggregates. Comparative Example 4 showed bidirectional segregation with PET floating and aggregate settling, resulting in a chaotic internal structure. These results validate the rationality of the layered paving and targeted rheological design employed in this invention, solving the technological challenges of floating and segregating lightweight inert aggregates in an asphalt matrix.

[0061] Test Example 2: Experimental steps: According to T0730-2000 "Test Method for Water Permeability of Asphalt Pavement", the molded composite structure specimen was placed on the test platform and the surface was cleaned. A permeability meter was installed and the base edge was sealed. Water was filled to the scale line, and the switch was turned on. The time required for the water level to drop to a certain height or the amount of water permeation within 3 minutes was recorded, and the permeability coefficient was calculated. Interlaminar shear strength was tested using a self-designed interlaminar shear mold and a universal testing machine. A 100mm diameter core sample was drilled from the composite specimen. The interface between the PET waterproof layer and the wearing layer was placed on the center line of the shear fixture. A vertical shear load was applied at a rate of 50mm / min until failure. The maximum failure load was recorded and the strength was calculated. According to the T0715 small beam bending test method in JTGE20-2011, the composite specimen was cut into 250mm×30mm×35mm prism beams. After being kept at -10℃ for 4 hours, a three-point bending loading test was performed at a loading rate of 50mm / min. The mid-span deflection at fracture was recorded, and the tensile strain at failure was calculated. According to ISSATB147 standard, load wheel rutting test (LWT) was carried out. After the mixture was laid, shaped and cured, it was placed on the wheel rutting tester and subjected to 1000 cycles of wheel load compaction at 60℃. The deformation depth of the specimen surface and the displacement of asphalt mixture per unit width were measured before and after compaction.

[0062] Table 2. Test results of road performance of each group of composite structures

[0063] Conclusions and Mechanism Analysis: Table 2 shows that the permeability coefficients of Examples 1, 2, and 4 were 0 mL / min, while Example 3 was 2.5 mL / min, achieving a water-impermeable effect. In contrast, Comparative Example 3 had a permeability coefficient of 145.7 mL / min. The data differences validate the role of the rheological control system: in the examples, the thixotropic emulsion restricted the vertical migration of the PET discs, causing them to form an ordered layered structure under gravity, thus constructing a physical water-blocking barrier. Comparative Example 3 lacked rheological control, resulting in PET floating and agglomeration, leaving only asphalt at the bottom and failing to form a continuous dense layer. Comparative Example 1, due to the inherent porosity between the aggregates, had a permeability coefficient of 68.4 mL / min, indicating that the dense structure of the PET material has a water-blocking advantage.

[0064] In terms of mechanical properties, the low-temperature failure flexural strain of the examples was in the range of 4630-5120 με, higher than the 2250 με of the conventional structure in Comparative Example 1. This difference stems from the low modulus characteristics of PET material. When the composite structure is subjected to flexural load, the bottom PET absorbs and dissipates stress through elastic deformation, delaying crack propagation. In the interlaminar shear strength test, the example group maintained 0.79-0.85 MPa, close to the 0.95 MPa of the all-stone structure in Comparative Example 1, indicating that the bonding strength of the heterogeneous materials meets the requirements. The shear strengths of Comparative Example 2 (untreated) and Comparative Example 5 (without tack coat) were 0.18 MPa and 0.25 MPa, respectively, confirming that the chemical bonding introduced by surface activation and the tack coat penetration process during a specific window period are necessary means to prevent interlaminar slip.

[0065] LWT rut depth data reflects the structure's resistance to deformation. Comparative Example 2 showed a rut depth of 8.6 mm due to interlayer bonding failure, indicating structural damage. The rut depth in the example group was controlled within the range of 3.2-4.1 mm, close to Comparative Example 1, indicating that the introduction of the flexible PET underlayer did not significantly reduce the overall structure's high-temperature stability. Comparative Example 4, using a blending process, had a permeability coefficient of 82.3 mL / min, with all indicators falling within the middle range, failing to demonstrate the water-blocking and crack-resistant advantages of the layered structure. In summary, by constructing a thixotropic rheological system to achieve the directional arrangement of lightweight aggregates, and combining this with surface chemical modification to enhance interfacial bonding, a composite structure with a sealing lower layer and a wear-resistant upper layer was formed, improving the road surface's waterproof and crack-resistant performance.

[0066] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composite slurry sealant with a biomimetic scale-structured waterproof layer, characterized in that, The composite slurry seal layer consists of a two-layer composite structure from bottom to top, comprising a waterproof functional layer, an interlayer adhesive layer, and an abrasion functional layer. The raw materials for the waterproof functional layer include modified PET aggregate, thixotropic modified emulsified asphalt, active filler, and water; The modified PET aggregate is a polyester sheet with a surface activation treatment; The thixotropic modified emulsified asphalt contains a rheology modifier, and based on 100 parts of the dry weight of the modified PET aggregate, the equivalent pure asphalt content of the thixotropic modified emulsified asphalt is 8.0 to 12.0 parts. The raw material for the interlayer bonding layer is diluted slow-cracking emulsified asphalt; The raw materials for the wear-resistant functional layer include mineral aggregates, emulsified asphalt, and fillers.

2. The composite slurry sealant with a biomimetic scale structure waterproof layer according to claim 1, characterized in that, The modified PET aggregate is a circular sheet with a diameter of 5.5 to 6.5 mm and a thickness of 0.5 to 1.0 mm, and the surface activation treatment layer of the modified PET aggregate is a silane coupling agent graft layer or a plasma oxidation layer. The raw materials for the thixotropic modified emulsified asphalt include slow-cracking, fast-setting cationic emulsified asphalt, cationic styrene-butadiene latex, and rheology modifiers. The rheology modifier is organic modified bentonite or modified nanocellulose; based on the mass of the slow-cracking fast-setting cationic emulsified asphalt, the amount of cationic styrene-butadiene latex is 3.0% to 5.0%, and the dry weight amount of the rheology modifier is 0.5% to 1.5%.

3. The composite slurry sealant with a biomimetic scale structure waterproof layer according to claim 1, characterized in that, The modified PET aggregate has a base material that is a modified copolyester with a heat shrinkage initiation temperature in the range of 45 to 60 degrees Celsius; and the surface micropores of the modified PET aggregate adsorb latent curing agent components.

4. The composite slurry sealant with a biomimetic scale structure waterproof layer according to claim 1, characterized in that, The raw materials of the waterproof functional layer also include a stabilizer, which is lignin fiber or mineral fiber, and the amount used is 0.1% to 0.3% of the mass of the modified PET aggregate; the active filler is ordinary silicate cement, and the amount used is 1.0% to 2.0% of the mass of the modified PET aggregate.

5. The composite slurry sealant with a biomimetic scale structure waterproof layer according to claim 1, characterized in that, The asphalt residue distribution of the diluted slow-cracking emulsified asphalt in the interlayer bonding layer is 0.3 to 0.5 kg per square meter; the mineral aggregate in the abrasion functional layer is basalt or diabase crushed stone.

6. The method for preparing the composite slurry seal with a biomimetic scale structure waterproof layer according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Preparation of modified PET aggregate: Surface activation treatment of PET sheets; S2. Preparation of thixotropic modified emulsified asphalt: Rheology modifiers are added to emulsified asphalt and shear dispersion is performed; S3. Waterproof functional layer construction: The modified PET aggregate, thixotropic modified emulsified asphalt, active filler and water are mixed to form the first mixture, which is then spread on the road surface to form a waterproof functional layer. S4. Interlayer bonding treatment: When the waterproof functional layer is in a state of contact dryness and not fully hardened, spray adhesive oil on its surface. S5. Construction of the wear-resistant functional layer: After the tack coat is demulsified, the second mixture formed by mixing mineral aggregates, emulsified asphalt and fillers is spread on the interlayer bonding layer and cured to form a double-layer composite structure.

7. The method for preparing the composite slurry seal with a biomimetic scale structure waterproof layer according to claim 6, characterized in that, The specific methods of surface activation treatment in step S1 include: After cleaning and drying the PET sheet, immerse it in an alcohol-water solution containing 1.5% to 3.0% silane coupling agent, adjust the pH value to 3.5 to 4.5, soak it at 25 to 40 degrees Celsius for 20 to 40 minutes, and then heat-cur it at 100 to 110 degrees Celsius. The PET sheet is placed in a vacuum reaction chamber, and oxygen or argon is introduced. The plasma is then treated for 60 to 180 seconds at a power of 200 to 500 watts.

8. The method for preparing the composite slurry seal with a biomimetic scale structure waterproof layer according to claim 6, characterized in that, The specific preparation process of the thixotropic modified emulsified asphalt in step S2 is as follows: cationic styrene-butadiene latex is added to slow-cracking and fast-setting cationic emulsified asphalt and stirred evenly. Then, pre-dispersed organic modified bentonite slurry or nanocellulose suspension is added, and the mixture is sheared and mixed for 15 to 20 minutes at a speed of 3000 to 5000 rpm using a high-shear emulsifier.

9. The method for preparing the composite slurry seal with a biomimetic scale structure waterproof layer according to claim 6, characterized in that, In step S3, the yield stress of the first mixture is greater than the net buoyancy shear stress experienced by the modified PET aggregate in the emulsion matrix. The waterproof functional layer has a thickness of 8 to 10 mm, and the abrasion functional layer has a thickness of 6 to 8 mm.

10. The method for preparing the composite slurry seal with a biomimetic scale structure waterproof layer according to claim 6, characterized in that, In step S4, the state of being touched dry but not fully hardened is when the waterproof functional layer is applied 45 to 75 minutes after application and the surface color changes from brown to black. In step S5, the abrasion functional layer is applied within 15 to 30 minutes after the tack coat demulsifies and turns black.

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