Additive for improving abrasion resistance of ultrathin asphalt layer

Abstract

The invention discloses an additive for improving the abrasion resistance of an ultrathin asphalt layer and application of the additive, and belongs to the technical field of road engineering materials. The additive is prepared by compounding 50%-60% of plasma grafting modified nano electric arc furnace steel slag clusters, 20%-30% of steel slag epoxy microcapsules and 3%-5% of a silane coupling agent. The additive is doped in an amount which is 0.5 to 1.0 percent of the total mass of the ultra-thin asphalt mixture, the initial hardness and the wear resistance of a base layer are remarkably improved by nano steel slag clusters, and microcapsules are broken under the triggering of induction heating to release an epoxy repairing agent to realize damage self-healing. The invention also provides a corresponding mixture formula and a special construction process comprising low-temperature microcapsule addition and later induction activation. The Cantabro abrasion loss of the ultra-thin asphalt layer formed by the invention is less than or equal to 5%, the abrasion recovery rate after induction healing is more than or equal to 80%, and the ultra-thin asphalt layer can be repeatedly healed for multiple times, so that the service life of a pavement is greatly prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of road engineering materials, in particular to an additive for improving the wear resistance of an ultra-thin asphalt layer. BACKGROUND

[0002] As an important means of preventive maintenance of roads, the ultra-thin wearing layer technology is mainly used for repairing minor road diseases, restoring skid resistance, improving flatness, and sealing the road to prevent water. The typical thickness of this technology is 15-25mm. This technology is widely used in high-grade highway maintenance due to its fast construction speed, small traffic interference, and relatively low cost.

[0003] In the prior art, Chinese patent CN118667346A discloses a road ultra-thin wearing layer and a construction method thereof. This technology uses a composite material system including asphalt, glass fiber, sodium alginate, rubber, and various additives, and enhances the structural performance by laying two layers of steel mesh in the asphalt layer. This scheme improves the mechanical strength and durability of the ultra-thin wearing layer to some extent, especially by adding steel mesh to reduce cracking and by using high-grade alcohol as a modifier to improve the physical and mechanical properties of the mixture.

[0004] However, through in-depth analysis and practical verification, the technical solution disclosed in CN118667346A still has several obvious defects: first, the material components of this scheme are complex, involving various additives and modifiers, including anti-rutting agents, high-viscosity additives, anti-stripping agents, and anti-aging agents. The ratio requires precision, the production process control is difficult, and the product quality is unstable and the production cost is increased; second, multiple layering and steel mesh embedding are required during construction, which is a complicated process and requires high technical requirements for construction personnel, which is not conducive to large-scale popularization and application; third, although the scheme proposes the concept of steel mesh reinforcement, the interface bonding performance between the steel mesh and the asphalt material has not been fully optimized, and interface peeling may still occur under the action of long-term load and environmental factors; finally, the long-term durability of this technical solution in extreme climate conditions and heavy traffic environment still needs to be verified, especially in terms of fatigue resistance and temperature stress resistance. SUMMARY

[0005] (I) Technical problems solved In view of the deficiencies of the prior art, the present application provides an additive for improving the wear resistance of an ultra-thin asphalt layer, which solves the problems raised in the background art.

[0006] (II) Technical solutions To achieve the above purpose, the present application is implemented by the following technical solutions: an additive for improving the wear resistance of an ultra-thin asphalt layer, which is compounded by the following components in mass percentage: a) 50%-60% of nano-arc-furnace steel slag clusters with a particle size of 50-200 nm and grafted with epoxy groups on the surface; b) 20%-30% of steel slag epoxy microcapsules with the nano-arc-furnace steel slag clusters as the shell and an epoxy repair agent as the core; c) 3%-5% of a silane coupling agent.

[0007] Preferably, the Mohs hardness of the nano-arc-furnace steel slag clusters is ≥ 6.5, and the surface epoxy group grafting density is ≥ 1.2 mmol / g.

[0008] Preferably, the steel slag epoxy microcapsules have a particle size of 130-170 µm, a core-to-wall mass ratio of (1.5-2.5):1, and a shell thickness of 20-30 µm.

[0009] Preferably, the epoxy repair agent is a composite of a bisphenol A type epoxy resin and a latent curing agent, and the latent curing agent is a cycloaliphatic amine with an activation temperature of 65-75 °C.

[0010] An ultrathin asphalt layer mixture composed of aggregate, asphalt binder, and the additive described above; the amount of the composite additive is 0.5%-1.0% of the total mass of the ultrathin asphalt layer mixture; and the amount of the asphalt binder is 5.0%-7.0% of the total mass of the ultrathin asphalt layer mixture.

[0011] Preferably, the additive and the asphalt binder synergistically exert overall performance through a "point-line-plane" mechanism: the nano-steel slag clusters provide a high-hardness skeleton as "points", the steel slag microcapsule shell disperses stress as "planes", and the KH-550 coupling agent bridges the three through chemical bonds as "lines", thereby constructing a three-dimensional network that increases the DSR complex modulus G* by 42% and the fatigue life by 3.7 times; the BBR-10 °C test shows that the stiffness modulus S value decreases by 18% and the m value increases by 22%, and the low-temperature crack resistance is significantly improved; the freeze-thaw splitting strength ratio is ≥ 85% (25 percentage points higher than the blank sample), and SEM confirms that there is no water film at the interface, the coupling agent effectively blocks moisture erosion, and the water stability and durability are comprehensively improved.

[0012] Preferably, the asphalt binder is SBS modified asphalt.

[0013] A construction method for an ultrathin asphalt layer mixture, characterized by the following steps: Step one, heating the aggregate to 160 ± 5 °C and dry mixing; Step two, adding the asphalt binder for wet mixing to obtain an asphalt mixture base; Step three, after cooling the asphalt mixture base to below 100 °C, adding the additive and mixing at low speed until uniform; Step four, paving and compacting to form an ultra-thin asphalt layer with a thickness of 15-25 mm; Step five, within 24 hours after compaction, using an induction heating device to scan and heat the surface of the ultra-thin asphalt layer, so that the surface temperature rises to 70-75℃, triggering the steel slag epoxy microcapsule to break and achieve self-healing.

[0014] Preferably, the power of the induction heating device in step five is 20-40 kW, the frequency is 25-35 kHz, and the scanning moving speed is 4-6 km / h.

[0015] An ultra-thin asphalt layer, characterized in that it is paved by the above-mentioned ultra-thin asphalt layer mixture through the above-mentioned construction method, and has a Cantabro abrasion loss of ≤5%, an abrasion recovery rate of ≥50% after induction healing, and a low-temperature splitting strength ratio of ≥80%.

[0016] Preferably, the ultra-thin asphalt layer can repeat the induction healing process of step five for not less than 3 times within the service period, and the abrasion recovery rate after each healing is less than 10% lower than the previous time.

[0017] Preferably, the additive and the asphalt binder synergistically exert overall effectiveness through "point-line-surface": the nano steel slag cluster provides a high-hardness skeleton as "point", the steel slag microcapsule shell forms a "surface" to disperse stress, and the KH-550 coupling agent bridges the three with a chemical bond "line", constructing a three-dimensional network, so that the DSR complex modulus G* is increased by 42%, and the fatigue life is increased by 3.7 times; the BBR-10℃ test shows that the stiffness modulus S value is decreased by 18%, the m value is increased by 22%, and the low-temperature anti-cracking performance is significantly improved; the freeze-thaw splitting strength ratio is ≥85% (25 percentage points higher than the blank sample), and the SEM confirms that there is no water film at the interface, the coupling agent effectively blocks moisture erosion, and the water stability and durability are comprehensively improved.

[0018] Preferably, during on-site construction, a 30 kW, 30 kHz mobile induction coil vehicle is used, the coil is 30 mm away from the road surface, and the scanning speed is 5 km / h; an infrared thermal imager is used for real-time monitoring to ensure that the surface temperature rise uniformity is ±3℃, and the power is automatically reduced in the over-temperature area; the compaction is divided into three stages, the initial pressure is 110℃, the re-compaction is 90℃, and the final pressure is controlled to be ≤65℃, the microcapsule integrity rate is >98%, and the compaction degree is ≥97%; within the design service life of the pavement, the microcapsule can be triggered to break and heal again by using a 20 kW power to quickly scan 0.2 h / km every 2-3 years, the healing efficiency is maintained at >80%, and there is no need for milling and repaving, achieving low-cost, long-life maintenance.

[0019] (Three) beneficial effects The present application provides an additive for improving the abrasion resistance of an ultra-thin asphalt layer, which has the following beneficial effects: This invention incorporates steel slag epoxy microcapsules in a single step, replacing the multi-component system of steel mesh, anti-rutting agent, anti-stripping agent, and anti-aging agent in the prior art. The formula is simple and the metering error is small. At the same time, all components can be added at a low temperature below 100°C to avoid high-temperature decomposition, which significantly reduces the difficulty of process control and production cost, and solves the problems of complex material composition and cumbersome process in the prior art.

[0020] By chemically bonding nano-steel slag clusters with asphalt and triggering immediate healing of microcapsules when microcracks appear, the interfacial bonding strength can be restored to over 85% within 30 seconds, achieving ≥3 repeated healings during the service life, with a wear recovery rate decrease of <10% after each healing. Thus, it maintains stable crack resistance and wear resistance under extreme conditions such as high cold and heavy loads, overcoming the shortcomings of existing technologies such as easy interface peeling and poor durability in extreme climates. Attached Figure Description

[0021] Figure 1 This is a construction diagram of the present invention. Detailed Implementation

[0022] The technical solutions of 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.

[0023] Example 1: like Figure 1 As shown in the figure, an embodiment of the present invention provides a preparation process for an additive to improve the wear resistance of ultra-thin asphalt layers, comprising the following steps: S1. Preparation and Modification of Nano-Steel Slag Clusters: Electric arc furnace steel slag was placed in a planetary ball mill and milled at 450 rpm for 2 hours. After sieving, nano-steel slag powder with a particle size between 50-200 nm was obtained. The nano-steel slag powder was placed in a plasma treatment device and treated with oxygen plasma at 1000 W for 30 seconds under an argon atmosphere of 0.1 MPa. After treatment, epoxy groups were successfully grafted onto its surface, and the grafting density was determined to be 1.3 mmol / g by titration. Its Mohs hardness was tested to be 6.8.

[0024] S2. Using in-situ polymerization, modified nano-steel slag was used as the wall material to encapsulate the core of the aforementioned epoxy repair agent. With strict control of reaction conditions, microcapsules with an average particle size of 155 μm and an outer shell thickness of approximately 25 μm were obtained. Microscopic image analysis showed an encapsulation rate greater than 96%.

[0025] The core repairing agent is prepared by pre-mixing bisphenol A type epoxy resin (E-51) and aliphatic amine latent curing agent (Ancamine 2441) at a mass ratio of 100:35 at 60 DEG C to form an epoxy repairing agent system with appropriate viscosity, and the activation temperature of the system is 70 DEG C.

[0026] Shell material: the modified nano-steel slag cluster prepared in step 1.

[0027] S3, compounding of the composite additive, each component is weighed according to the following mass percentage: Modified nano-steel slag cluster: 55% Steel slag epoxy microcapsule: 25% Silane coupling agent KH-550: 4% SBS modified asphalt: 16%. (Note: The SBS modified asphalt here is only used to bond and disperse the above functional components during storage and transportation to form a granular or block-shaped additive product, and is not the main asphalt binder in the mixture.) S4, all the above components are mechanically mixed at a speed of 400 rpm for 15 seconds at 85 DEG C to make them uniformly mixed, and then granulated after cooling to obtain the final composite additive product A1.

[0028] Example two: The application provides a preparation process of an additive for improving the wear resistance of an ultrathin asphalt layer, which comprises the following steps: S1, preparation and modification of nano-steel slag clusters: arc furnace steel slag is placed in a planetary ball mill and ball milled at a speed of 450 rpm for 2 hours, and then sieved to obtain nano-steel slag powder with a particle size of 50-200 nm; the nano-steel slag powder is placed in a plasma treatment device, and subjected to oxygen plasma treatment at a power of 1000 W for 30 seconds in an argon atmosphere at 0.1 MPa. After the treatment, epoxy groups are successfully grafted onto the surface, and the grafting density is 1.3 mmol / g as determined by titration. The Mohs hardness is tested to be 6.8.

[0029] S2, in-situ polymerization is used to coat the above-mentioned epoxy repairing agent core with the modified nano-steel slag as the wall material. The reaction conditions are strictly controlled, and finally the microcapsules with an average particle size of 155 μm and a shell thickness of about 25 μm are obtained. The coating rate is greater than 96% through microscopic image analysis and statistics.

[0030] The core repairing agent is prepared by pre-mixing bisphenol A type epoxy resin (E-51) and aliphatic amine latent curing agent (Ancamine 2441) at a mass ratio of 100:35 at 60 DEG C to form an epoxy repairing agent system with appropriate viscosity, and the activation temperature of the system is 70 DEG C.

[0031] Shell material: modified nano-steel slag clusters prepared in step 1.

[0032] S3, compounding of the composite additive, each component is weighed according to the following mass percentage: 60% modified nano-steel slag clusters, 20% steel slag epoxy microcapsules, 5% silane coupling agent KH-550, and 15% SBS modified asphalt.

[0033] S4, all the above components are mechanically mixed at a speed of 400 rpm for 15 seconds at 85°C to make them uniformly mixed, and then granulated after cooling to obtain the final composite additive product A2.

[0034] Example Three: The construction method of the ultra-thin asphalt layer mixture comprises the following steps: S1. Mixture mixing: AC-10 gradation design asphalt mixture is used; the aggregate is heated to 165°C and dry mixed in the mixing kettle for 5 seconds; 6.0% SBS modified asphalt (binder) of the total mass of the mixture is added, and wet mixed for 40 seconds to make the aggregate completely wrapped; the mixed asphalt mixture matrix is cooled to 95°C; 0.8% of the composite additive A1 prepared in Example 1 of the total mass of the mixture is added, and mixed at a low speed of 300 rpm for 15 seconds, and then discharged. The whole process ensures that the microcapsules will not be broken prematurely due to high temperature during mixing.

[0035] S2, paving and compaction: the mixture is spread to a thickness of 10 mm, and a double steel roller compactor is used to compact the mixture immediately after paving to achieve a compaction density of more than 97% of the maximum theoretical density.

[0036] S3, induction activated self-healing: within 12 hours after compaction, a mobile induction heating equipment with a power of 30 kW and a frequency of 30 kHz is used to scan the newly built pavement at a speed of 5 km / h; the infrared thermal imager monitoring shows that the surface temperature of the pavement is uniformly raised to 72°C. This temperature effectively triggers the activation of the epoxy resin curing agent in the microcapsule, causing the capsule to break, the epoxy resin to flow out and to be cured in a short time, and the self-repair of microcracks and damages is achieved.

[0037] Comparative Example Without adding any composite additive, only SBS modified asphalt (6.0%) is used to mix with the aggregate to form a conventional ultra-thin asphalt mixture. The paving and compaction process is exactly the same as Example 3, but no induction heating treatment is performed.

[0038] Performance test and result analysis Test sample explanation: the following data are respectively the test results of the ultra-thin asphalt layer formed by adding additives A1, A2 and the comparative example without adding any additive, and all of them are formed by the construction method described in Example Three.

[0039] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be made without departing from the spirit and scope of the present application, which is defined by the following claims and their equivalents.

Claims

1. An additive for improving the wear resistance of ultra-thin asphalt layers, characterized in that, It is a compound of the following components in the indicated mass percentages: a) 50%-60% of plasma-grafted modified nano-electric arc furnace slag clusters with a particle size of 50-200nm and epoxy groups grafted onto the surface. b) 20%-30% steel slag epoxy microcapsules, which have the aforementioned nano electric arc furnace steel slag clusters as the outer shell and epoxy repair agent as the core; c) 3%-5% silane coupling agent.

2. The composite additive according to claim 1, characterized in that, The nano-electric arc furnace slag clusters have a Mohs hardness ≥6.5 and a surface epoxy grafting density ≥1.2mmol / g.

3. The composite additive according to claim 1, characterized in that, The steel slag epoxy microcapsules have a particle size of 130-170µm, a core-to-wall mass ratio of (1.5-2.5):1, and a shell thickness of 20-30µm.

4. The composite additive according to claim 1, characterized in that, The epoxy repair agent is a composite of bisphenol A type epoxy resin and a latent curing agent, wherein the latent curing agent is an alicyclic amine with an activation temperature of 65-75℃.

5. A thin asphalt layer mixture, characterized in that, It is composed of aggregates, asphalt binder and additives as described in any one of claims 1-4; the amount of the composite additive is 0.5%-1.0% of the total mass of the ultra-thin asphalt layer mixture; the amount of the asphalt binder is 5.0%-7.0% of the total mass of the ultra-thin asphalt layer mixture.

6. The ultra-thin asphalt layer mixture according to claim 5, characterized in that, The asphalt binder is SBS modified asphalt.

7. A construction method for an ultra-thin asphalt layer mixture as described in claim 5 or 6, characterized in that, Includes the following steps: Step 1: Heat the aggregate to 160±5℃ and dry mix it; Step 2: Add the asphalt binder and wet mix to obtain the asphalt mixture matrix; Step 3: After cooling the asphalt mixture matrix to below 100°C, add the additive and mix at low speed until uniform. Step 4: Spread and compact the asphalt to form an ultra-thin asphalt layer with a thickness of 15-25mm; Step 5: Within 24 hours after compaction, the surface of the ultra-thin asphalt layer is scanned and heated using an induction heating device to raise its surface temperature to 70-75℃, triggering the rupture of the steel slag epoxy microcapsules and achieving self-healing.

8. The construction method according to claim 7, characterized in that, The power of the induction heating device mentioned in step five is 20-40kW, the frequency is 25-35kHz, and the scanning movement speed is 4-6km / h.

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