Material for intelligent pavement, self-sensing and self-repairing intelligent pavement and implementation method of self-sensing and self-repairing intelligent pavement

Abstract

The invention relates to the technical field of intelligent pavements, in particular to a material for an intelligent pavement, a self-sensing and self-repairing intelligent pavement and an implementation method of the self-sensing and self-repairing intelligent pavement. The material for the intelligent pavement comprises a mixture of a matrix binding material, a self-sensing unit and a self-repairing unit, the mass of the self-sensing unit is 0.3%-1.5% of the mass of the matrix binding material, and the self-sensing unit is selected from at least one of a carbon-based nano material and short carbon fibers; the self-repairing unit comprises a microcapsule repairing agent and a shape memory fiber. The three-in-one framework of the intelligent surface layer, the induction monitoring network and the intelligent control system can realize self-sensing of the health state of the road surface; when a crack occurs at the position of the microcapsule, the microcapsule shell can be passively broken to release a repairing agent to fill the crack, and meanwhile, after a damage sign is found through self-sensing, the shape memory fiber can be triggered to actively repair.

Description

Technical Field

[0001] This invention relates to the field of intelligent road technology, specifically to an intelligent road material, a self-sensing and self-healing intelligent road, and a method for implementing the same. Background Technology

[0002] As the core carrier bearing traffic loads and ensuring traffic efficiency, the service performance and durability of road surfaces directly affect the safe and stable operation of transportation networks. Microcracks and decreased smoothness in road surfaces gradually weaken the load-bearing capacity of the pavement structure, leading to structural damage, shortening road lifespan, and increasing maintenance costs and traffic congestion risks, seriously impacting the safety and economy of transportation. Against this backdrop, traditional road construction models relying on passive maintenance are no longer sufficient to meet the modern transportation demands for long-life, low-maintenance, and highly safe pavements. Developing intelligent pavement technologies with the ability to actively sense damage and autonomously repair defects has become an important development direction in the field of road engineering materials, and is of great significance for promoting the transformation of transportation infrastructure towards intelligence and sustainability.

[0003] To address the challenges posed by road defects, the industry has conducted extensive research and practice, resulting in a series of targeted solutions. In terms of defect repair, self-healing material technology has made significant progress. This involves incorporating microcapsules into asphalt mixtures or cement concrete. The mechanical stress generated during crack propagation causes the capsules to rupture, releasing the encapsulated epoxy resin, asphalt rejuvenator, or mineral binder. Capillary action and chemical reactions then fill and solidify the cracks. Regarding damage detection, intelligent sensing technology is maturing. By embedding conductive fillers into the pavement structure to form a three-dimensional conductive network, damage monitoring is achieved by utilizing the resistivity changes caused by the breakage of conductive pathways when cracks occur. The application of devices such as piezoelectric sensing fibers and fiber optic grating sensors enables real-time acquisition of pavement stress, strain, and temperature signals, providing data support for early warning of road defects.

[0004] Although existing technologies have achieved some success in pavement damage detection and repair, they still have significant limitations in practical engineering applications. In existing technologies, the sensing and repair units are mostly deployed independently, lacking integrated design. The spatial layout of the sensing network and repair system lacks coordinated optimization, resulting in poor damage signal transmission paths and difficulty in accurately matching the release of repair agents with the location of cracks, thus affecting sensing sensitivity and repair efficiency. Summary of the Invention

[0005] To address the current lack of intelligent pavements with both self-sensing and self-repairing capabilities, this invention provides an intelligent pavement material, a self-sensing and self-repairing intelligent pavement, and its implementation method. When structural damage or changes in temperature and stress occur inside the road, the integrated architecture of the intelligent surface layer, sensing monitoring network, and intelligent control system of this invention enables self-sensing of the pavement's health status. When cracks occur at the microcapsule location, the microcapsule shell can passively rupture to release a repair agent to fill the crack. Simultaneously, after self-sensing and detecting signs of damage, this invention can also actively repair the damage by triggering shape memory fibers.

[0006] The technical solution of this invention is as follows: In a first aspect, the present invention provides a material for intelligent road surfaces, comprising a mixture of a matrix binder, a self-sensing unit, and a self-healing unit; The matrix binder is either asphalt-based or cement-based. The mass of the self-sensing unit is 0.3% to 1.5% of the mass of the matrix binder. The self-sensing unit is selected from at least one of carbon-based nanomaterials and short-cut carbon fibers. Carbon-based nanomaterials include carbon nanotubes, graphene, etc. The self-healing unit includes a microcapsule repair agent and shape memory fibers. The mass of the microcapsule repair agent is 3% to 8% of the mass of the matrix binder, and the mass of the shape memory fibers is 0.1% to 0.6% of the mass of the matrix binder.

[0007] Furthermore, the core of the microcapsule repair agent contains asphalt rejuvenator or epoxy resin.

[0008] Furthermore, the shape memory fiber is a shape memory polymer (SMP) fiber or a shape memory alloy (SMA) fiber, with an activation temperature range of 50℃ to 80℃.

[0009] Secondly, the present invention provides a self-sensing and self-repairing intelligent road surface, including an intelligent surface layer, a sensing and monitoring network, and an intelligent control system. The intelligent surface layer is constructed from the aforementioned intelligent pavement materials. Specifically, the intelligent surface layer is composed of a matrix binder, self-sensing units, and self-healing units. The self-sensing units form a three-dimensional conductive network within the matrix binder, used to output signals indicating relative resistivity changes caused by pavement damage. ; The sensing and monitoring network is embedded in or beneath the smart surface layer, including features for data collection. Electrode grids and temperature sensors; The intelligent control system is electrically connected to an induction monitoring network for receiving signals. The signal is sent, and a repair trigger command is output according to a preset threshold. The repair activation unit activates the shape memory fibers in the self-repair unit to achieve autonomous repair of the crack.

[0010] Furthermore, it is used for collection The electrode grid for the signal includes an electrode grid laid out using the four-terminal method or electrical impedance tomography technique, with an electrode spacing of 5cm to 10cm.

[0011] Furthermore, the sensing monitoring network also includes piezoelectric fiber and / or fiber optic grating sensors for stress monitoring. The piezoelectric fiber and fiber optic grating sensors are embedded at the bottom of the smart surface layer to assist in damage diagnosis.

[0012] Furthermore, the repair activation unit is an electromagnetic induction heating device or an infrared heating device.

[0013] Thirdly, the present invention provides a method for implementing the above-mentioned self-sensing and self-repairing intelligent road surface, comprising the following steps: S1: Weigh the matrix binder, self-sensing unit and self-healing unit according to the preset formula. First, mix the matrix binder and self-sensing unit evenly at the first temperature and / or the first speed. Then, embed the self-healing unit into the mixture at the second temperature and / or the second speed. S2: Electrode grids and temperature sensors are embedded in the road structure layer, and the materials for the smart road are paved and compacted. S3: Connect the electrode grid and temperature sensor to the data acquisition system, and connect the data acquisition system to the cloud-based intelligent control platform; S4: Intelligent service and active repair. The data acquisition system continuously collects signals. When the signal reaches the preset trigger threshold, the repair activation unit is automatically activated to perform local repair on the damaged area.

[0014] Furthermore, in S1, the first temperature is 150~170℃, and the second temperature is below 40℃.

[0015] Furthermore, in S1, the first speed is 1500~3000rpm and the second speed is 100~300rpm.

[0016] The beneficial effects of this invention are as follows: The intelligent pavement material provided by this invention, through a rational ratio of matrix binder, self-sensing units, and self-healing units, can form a stable three-dimensional conductive network in the matrix, capturing resistivity changes caused by pavement damage. Simultaneously, the microcapsule repair agent and shape memory fibers work synergistically; the microcapsules passively release the repair agent to fill microcracks, while the shape memory fibers actively shrink and close cracks at an activation temperature of 50℃~80℃, endowing the material with both passive and active repair capabilities. This intelligent pavement material retains the mechanical strength and workability of traditional road materials while adding intelligent characteristics of self-sensing and self-healing.

[0017] The self-sensing and self-healing smart road surface provided by this invention, which uses the above-mentioned smart road surface material as one of the raw materials, can simultaneously realize damage detection and self-healing, breaking through the limitation of functional separation in the prior art, reducing the frequency of manual inspection and large-scale maintenance, and improving the economic efficiency of the road throughout its entire life cycle.

[0018] The implementation method of the self-sensing and self-repairing intelligent road surface provided by the present invention is highly compatible with the existing road construction system. During the material mixing stage, the self-repairing unit is avoided by operating at different temperatures and speeds, and the functional units are evenly distributed. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0020] This invention provides a smart pavement material, a self-sensing and self-repairing smart pavement, and its implementation method. It has application and development prospects in the construction and maintenance of various transportation infrastructures such as highways, urban roads, and airport runways. It can solve the technical problems of traditional pavement materials being prone to defects, having high maintenance costs, and having a disconnect between sensing and repair functions, and realize real-time monitoring, autonomous repair, and long-term service of pavement damage.

[0021] The purpose of this invention is to provide an intelligent road surface solution that integrates self-sensing and self-healing characteristics, specifically achieving the following functions: First, real-time sensing of crack generation and propagation during road service (relative resistivity change signal). First, it provides accurate data support for damage assessment by analyzing temperature changes and stress distribution. Second, through a passive and active collaborative repair mechanism, it achieves automatic crack healing and mechanical property restoration, completing damage treatment without manual intervention. Third, it has long-term cyclic repair capabilities, supporting multiple damage and repair cycles by using shape memory fibers, thus extending the service life of the road surface.

[0022] To achieve the above objectives, the present invention first employs a smart road surface material, comprising a mixture of a matrix binder, a self-sensing unit, and a self-healing unit.

[0023] The matrix binder is either asphalt-based or cement-based, such as SBS modified asphalt or P·O 52.5R high-performance silicate cement. Both types of matrices must meet the basic requirements of road engineering for mechanical strength, durability, and workability.

[0024] The mass of the self-sensing unit is 0.3% to 1.5% of the mass of the matrix binder. The self-sensing unit is selected from at least one of carbon-based nanomaterials and short-cut carbon fibers. Carbon-based nanomaterials include carbon nanotubes, graphene, etc.

[0025] The self-healing unit includes a microcapsule repair agent and shape memory fibers. The mass of the microcapsule repair agent is 3% to 8% of the mass of the matrix binder. The microcapsule repair agent can be an existing microcapsule repair agent with a core containing asphalt recycling agent or epoxy resin. The mass of the shape memory fiber is 0.1% to 0.6% of the mass of the matrix binder. The shape memory fiber is a shape memory polymer (SMP) fiber or a shape memory alloy (SMA) fiber, and its activation temperature range is 50℃ to 80℃.

[0026] Using the aforementioned intelligent pavement materials, a self-sensing and self-healing intelligent pavement is obtained. Its construction and application methods follow a process of paving and forming, service sensing, self-healing activation, and cyclical maintenance, including the following steps: S1: Weigh the matrix binder, self-sensing unit and self-healing unit according to the preset formula. First, mix the matrix binder and self-sensing unit evenly at the first temperature and / or the first speed. Then, embed the self-healing unit into the mixture at the second temperature and / or the second speed. S2: Electrode grids and temperature sensors are embedded in the road structure layer, and the materials for the smart road are paved and compacted. S3: Connect the electrode grid and temperature sensor to the data acquisition system, and connect the data acquisition system to the cloud-based intelligent control platform; S4: Intelligent service and active repair. The data acquisition system continuously collects signals. When the signal reaches the preset trigger threshold, the repair activation unit is automatically activated to perform local repair on the damaged area.

[0027] The specific steps are as follows: S1: Weigh the matrix binder, self-sensing unit, and self-healing unit according to the preset formula. First, preheat the matrix binder to the set temperature. The preheating temperature for asphalt-based materials is 150-180℃, and for cement-based materials, it is controlled at 20-30℃. Then, add the self-sensing unit and mix at 1000-3000 rpm for 5-20 minutes. Next, when the temperature drops to ≤40℃, add the self-healing unit according to the ratio and stir at a low speed of 100-300 rpm for 2-5 minutes to avoid damage to the functional units, and finally form a uniform intelligent road surface mixture.

[0028] S2: Electrode grids and temperature sensors are embedded in the road structure layer, and the materials for the intelligent road surface are paved and compacted. The paving speed is controlled at 3-6 m / min, and the surface layer thickness is designed to be 30-80 mm according to the road grade. The compaction is carried out in 2-3 passes using a double steel drum roller. The initial compaction uses 5-10t static pressure, the intermediate compaction uses 70Hz medium frequency vibration, and the final compaction uses 5-10t static pressure. The compaction speed is 0.5-1.0 m / s.

[0029] S3: Connect the electrode grid and temperature sensor to the data acquisition system, and connect the data acquisition system to the cloud-based intelligent control platform. The data acquisition system can then transmit the received data to the cloud-based intelligent control platform via NB-IoT.

[0030] S4: Intelligent Service and Active Repair. The data acquisition system continuously collects signals, and when the cloud-based intelligent control platform detects a relative change in resistivity... When the preset trigger threshold is reached, the repair activation unit is automatically activated to perform localized repair on the damaged area. An electromagnetic induction heating device or an infrared heating device heats the road surface, causing the shape memory fibers to shrink and close the cracks. Simultaneously, during the active physical repair process of the shape memory fibers, the microcapsule repair agent ruptures due to the stress generated by crack propagation, releasing internal repair agents to fill the cracks. The physical and chemical repairs work synergistically; physical repair achieves rapid crack closure, while chemical repair achieves long-term consolidation.

[0031] Example 1 A smart road material comprising a mixture of a matrix binder, a self-sensing unit, and a self-healing unit; The matrix binder is SBS modified bitumen, ID grade, with a penetration of 60~80dmm (25℃, 100g, 5s) and a softening point ≥75℃. The self-sensing unit uses chopped carbon fiber, specifically T700, and the mass of the chopped carbon fiber is 1.5% of the mass of the matrix binder. The self-healing unit includes a microcapsule repair agent and shape memory fibers. The microcapsule repair agent is a polyurethane shell microcapsule with a particle size of 100 μm, a wall thickness of 8 μm, and a core consisting of E-51 epoxy resin and curing agent in a mass ratio of 2:1. The mass of the polyurethane shell microcapsule is 3% of the mass of the matrix binder. The shape memory fiber is a NiTi shape memory alloy fiber with a diameter of 100 μm, a length of 10 mm, and a phase change temperature of 60℃. The mass of the shape memory fiber is 0.3% of the mass of the matrix binder.

[0032] The above-mentioned intelligent road materials are used for the paving of self-sensing and self-healing intelligent roads. The self-sensing and self-healing intelligent road includes an intelligent surface layer, a sensing and monitoring network, and an intelligent control system. The intelligent surface layer is constructed from the aforementioned intelligent pavement materials. Specifically, the intelligent surface layer is composed of a matrix binder, self-sensing units, and self-healing units. The self-sensing units form a three-dimensional conductive network within the matrix binder, used to output signals indicating relative resistivity changes caused by pavement damage. ; The sensing and monitoring network is embedded in or beneath the smart surface layer, including features for data collection. The device consists of an electrode grid, a temperature sensor, piezoelectric fibers, and a fiber optic grating sensor. The electrode grid uses silver-plated copper electrodes (50mm×50mm×1mm) arranged in a four-terminal method with an electrode spacing of 8cm. There are 10 temperature sensors, 20 piezoelectric fibers (model PZT-5H), and 5 fiber optic grating sensors (model FBG-1550). The intelligent control system includes a data acquisition system and a cloud-based intelligent control platform. The intelligent control system is electrically connected to an induction monitoring network for receiving data. The signal is sent and a repair trigger command is output according to a preset threshold. The repair activation unit (medium frequency electromagnetic induction heater) activates the shape memory fiber in the self-repair unit to realize the autonomous repair of the crack.

[0033] The aforementioned self-sensing and self-healing intelligent pavement is constructed and applied according to the following implementation method: S1: First, add SBS modified asphalt to a high-shear mixer, heat to 160℃, and stir at 2000 rpm for 5 minutes; then add short-cut carbon fibers, maintain the temperature at 160℃ and the speed at 2000 rpm, and continue stirring for 15 minutes. After cooling to 30℃, add microcapsule repair agent and shape memory fiber according to the formula, and stir at low speed of 200 rpm for 5 minutes to finally obtain a uniform intelligent road material.

[0034] S2: On the base layer of the road surface to be constructed, copper-plated silver electrode grids are laid at 8cm intervals. Ten temperature sensors are buried at the nodes of the electrode grids. Twenty PZT-5H piezoelectric fibers and five FBG-1550 fiber optic grating sensors are evenly buried at the bottom of the surface layer. The leads of the sensors and electrodes are all led to the roadside control box using high-temperature shielded cables.

[0035] The intelligent pavement material is laid on the base layer using a paver at a speed of 4 m / min. Then, a double-drum roller is used for compaction. The initial compaction uses 5t static pressure at a speed of 0.8 m / s, and is carried out twice. The secondary compaction uses 70Hz medium-frequency vibration at a speed of 0.6 m / s, and is carried out three times. The final compaction uses 5t static pressure at a speed of 1.0 m / s, and is carried out twice. The compaction temperature is controlled at 120℃, which finally forms the intelligent surface layer.

[0036] S3: Connect the leads of the electrode grid, temperature sensor, piezoelectric fiber and fiber Bragg grating sensor to the data acquisition system in the roadside control box, and set the data acquisition parameters, for example: the resistance signal sampling frequency is 10Hz, the temperature signal sampling frequency is 1Hz, the piezoelectric signal sampling frequency is 500Hz, and the fiber Bragg grating signal sampling frequency is 10Hz.

[0037] The data acquisition system is connected to the cloud-based intelligent control platform via an NB-IoT module to complete system communication debugging and ensure that data can be uploaded to the cloud in real time.

[0038] S4: During the service of the intelligent road, when micro-cracks occur in the road surface, the three-dimensional conductive network formed by the self-sensing unit is destroyed, resulting in a change in local resistivity. The electrode grid converts the resistivity change signal into a voltage signal and transmits it to the data acquisition system. The temperature sensor collects the temperature signal of the intelligent road in real time, and the piezoelectric fiber and fiber optic grating sensors collect the road stress and strain signals, respectively. After analog-to-digital conversion by the data acquisition system, all signals are uploaded to the cloud intelligent control platform once per second through the NB-IoT module.

[0039] The cloud-based intelligent control platform has a built-in signal processing algorithm. First, it performs temperature compensation on the uploaded resistivity signal. The compensation formula is as follows:

[0040] In the formula, To compensate for the resistivity, For measured resistivity, The temperature coefficient of chopped carbon fiber is 0.0005 / ℃. For actual measured temperature, The reference temperature is 25℃.

[0041] The relative resistivity change signal was then calculated. , This is the baseline resistivity when the road surface is undamaged, which can be measured under undamaged conditions after construction. The platform's preset trigger threshold is... ≥30%, when calculated in real time When the threshold is reached or exceeded, the cloud-based intelligent control platform determines that cracks in the road surface require repair and immediately sends a repair trigger command; if If the percentage is less than 30%, then we will continue to monitor it in real time.

[0042] After receiving the repair trigger command from the cloud, road maintenance personnel activate the medium-frequency electromagnetic induction heater to locally heat the damaged area. The heating frequency is set to 200kHz, the power to 1kW, and the heating time to 5 minutes, raising the road surface temperature to 60℃. When the temperature reaches 60℃, the shape memory fibers shrink and deform, mechanically closing the road cracks. Simultaneously, the mechanical stress generated during crack expansion causes the polyurethane shell of the microcapsule repair agent to rupture, allowing the epoxy resin core to flow at the crack and cross-link with the curing agent, filling the crack gaps. The synergistic effect of physical and chemical repair achieves self-repair of the road cracks. After the repair is completed, the medium-frequency electromagnetic induction heater stops operating, and the road surface naturally cools to ambient temperature.

[0043] Twelve hours after the repair was completed, the cloud-based intelligent control platform again collected road surface resistivity, temperature, and stress signals. If the stress level drops below 10% and the stress signal recovers to more than 90% of its undamaged state, the repair is considered successful. If the repair standard is not met, the cloud platform will send a trigger command again to repeat the heating repair process until the repair requirements are met.

[0044] Example 2 A smart road material comprising a mixture of a matrix binder, a self-sensing unit, and a self-healing unit; The matrix binder is P·O 52.5R high-performance silicate cement; The self-sensing unit uses chopped carbon fiber, specifically T700, and the mass of the chopped carbon fiber is 1.5% of the mass of the matrix binder. The self-healing unit includes a microcapsule repair agent and shape memory fibers. The microcapsule repair agent is a polyurea shell microcapsule with a particle size of 150 μm, a wall thickness of 10 μm, and a core composed of asphalt recycling agent and petroleum fraction in a mass ratio of 3:1. The mass of the polyurea shell microcapsule is 8% of the mass of the matrix binder. The shape memory fiber is a shape memory polymer fiber with a diameter of 150 μm, a length of 15 mm, and a phase change temperature of 70℃. The mass of the shape memory fiber is 0.6% of the mass of the matrix binder.

[0045] The above-mentioned intelligent road materials are used for the paving of self-sensing and self-healing intelligent roads. The self-sensing and self-healing intelligent road includes an intelligent surface layer, a sensing and monitoring network, and an intelligent control system. The intelligent surface layer is constructed from the aforementioned intelligent pavement materials. Specifically, the intelligent surface layer is composed of a matrix binder, self-sensing units, and self-healing units. The self-sensing units form a three-dimensional conductive network within the matrix binder, used to output signals indicating relative resistivity changes caused by pavement damage. ; The sensing and monitoring network is embedded in or beneath the smart surface layer, including features for data collection. The electrode grid and temperature sensor are designed with silver-plated copper electrodes (50mm×50mm×1mm) and arranged using resistive tomography. The electrode spacing is 5cm and there are 15 temperature sensors. The intelligent control system includes a data acquisition system and a cloud-based intelligent control platform. The intelligent control system is electrically connected to an induction monitoring network for receiving data. The signal is sent, and a repair trigger command is output according to a preset threshold. The repair activation unit (infrared heating device) activates the shape memory fibers in the self-repair unit to achieve autonomous repair of the crack.

[0046] The aforementioned self-sensing and self-healing intelligent pavement is constructed and applied according to the following implementation method: S1: First, add P·O 52.5R high-performance silicate cement to the mixer, add water at 0.4 times the weight of the cement, and stir at 2000 rpm for 8 minutes; then add short-cut carbon fibers, maintain the speed, and continue stirring for 15 minutes. After cooling to 30℃, add microcapsule repair agent and shape memory fiber according to the formula, and stir at 200 rpm for 5 minutes to finally obtain a uniform intelligent road material.

[0047] S2: On the base layer of the road surface to be constructed, copper-plated silver electrode grids are laid at 5cm intervals. Fifteen temperature sensors are buried at the nodes of the electrode grids. The leads of the sensors and electrodes are all led to the roadside control box using high-temperature shielded cables.

[0048] The intelligent pavement material is laid on the base layer using a paver at a speed of 3 m / min. Then, a double-drum roller is used for compaction. The initial compaction uses 6t static pressure at a speed of 0.7 m / s for three passes; the intermediate compaction uses 65Hz medium-frequency vibration at a speed of 0.5 m / s for four passes; and the final compaction uses 6t static pressure at a speed of 0.9 m / s for three passes, ultimately forming the intelligent surface layer.

[0049] S3: Connect the leads of the electrode grid and temperature sensor to the data acquisition system in the roadside control box, and set the data acquisition parameters, for example: the resistance signal sampling frequency is 10Hz and the temperature signal sampling frequency is 1Hz.

[0050] The data acquisition system is connected to the cloud-based intelligent control platform via an NB-IoT module to complete system communication debugging and ensure that data can be uploaded to the cloud in real time.

[0051] S4: During the service of the intelligent road, when micro-cracks occur in the road surface, the three-dimensional conductive network formed by the self-sensing unit is destroyed, causing a change in local resistivity. The electrode grid converts the resistivity change signal into a voltage signal and transmits it to the data acquisition system. The temperature sensor collects the temperature signal of the intelligent road in real time. After all signals are converted from analog to digital by the data acquisition system, they are uploaded to the cloud intelligent control platform once per second through the NB-IoT module.

[0052] The cloud-based intelligent control platform has a built-in signal processing algorithm. First, it performs temperature compensation on the uploaded resistivity signal. The compensation formula is as follows:

[0053] In the formula, To compensate for the resistivity, For measured resistivity, The temperature coefficient of chopped carbon fiber is 0.0005 / ℃. For actual measured temperature, The reference temperature is 25℃.

[0054] The relative resistivity change signal was then calculated. , This is the baseline resistivity when the road surface is undamaged, which can be measured under undamaged conditions after construction. The platform's preset trigger threshold is... ≥25%, when calculated in real time When the threshold is reached or exceeded, the cloud-based intelligent control platform determines that cracks in the road surface require repair and immediately sends a repair trigger command; if If the percentage is less than 25%, then we will continue to monitor it in real time.

[0055] After receiving the repair trigger command from the cloud, road maintenance personnel activate the infrared heating device to locally heat the damaged area. The heating power is set to 1.5kW, and the heating time is 8 minutes, raising the road surface temperature to 70℃. When the temperature reaches 70℃, the shape memory fibers shrink and deform, mechanically closing the road cracks. Simultaneously, the mechanical stress generated during crack expansion causes the polyurea shell of the microcapsule repair agent to rupture, allowing the asphalt rejuvenator in the core to flow at the crack and react with petroleum fractions, filling the crack gaps. The synergistic effect of physical and chemical repair achieves self-repair of the road cracks. After the repair is completed, the infrared heating device stops working, and the road surface naturally cools to ambient temperature.

[0056] Twelve hours after the repair was completed, the cloud-based intelligent control platform again collected road surface resistivity, temperature, and stress signals. If the temperature drops below 8%, the repair is considered successful. If the repair standard is not met, the cloud platform will send a trigger command again to repeat the heating and repair process until the repair requirements are met.

[0057] Example 3 Example 3 is a laboratory simulation experiment of a self-sensing and self-repairing intelligent road surface. Cement-based blocks are used to simulate the road surface structure to verify the effectiveness of the self-sensing and self-repairing functions.

[0058] Materials for intelligent pavements include a mixture of matrix binder, self-sensing units, and self-healing units; The matrix binder is P·O 52.5R high-performance silicate cement; The self-sensing unit is made of a mixture of multi-walled carbon nanotubes and T300 chopped carbon fibers. The multi-walled carbon nanotubes have a diameter of 10 nm and a length of 20 μm, while the chopped carbon fibers have a length of 2 mm and a diameter of 7 μm. The carbon nanotubes account for 0.3% of the matrix binder mass, the chopped carbon fibers account for 0.7% of the matrix binder mass, and the total mass of the self-sensing unit accounts for 1.0% of the matrix binder mass. The self-healing unit comprises a microcapsule repair agent and shape memory fibers. The microcapsule repair agent is made of polyurethane shell microcapsules with a particle size of 80 μm, a wall thickness of 6 μm, and a core consisting of asphalt recycling agent and mineral binder in a 1:1 mass ratio. The mass of the microcapsule repair agent is 6% of the mass of the matrix binder. The shape memory fibers are made of shape memory polymer fibers with a diameter of 80 μm, a length of 8 mm, and a phase change temperature of 75℃. The mass of the shape memory fibers is 0.1% of the mass of the matrix binder.

[0059] The above-mentioned intelligent road materials were used to prepare cement-based blocks to simulate intelligent roads. The experimental cement-based blocks were 500mm×300mm×100mm in size and included a simulated intelligent surface layer, a micro-sensor monitoring network, and a laboratory intelligent control terminal. The simulated intelligent surface layer is cast from the aforementioned intelligent pavement materials. Self-sensing units form a three-dimensional conductive network within the matrix binder, used to output signals indicating relative resistivity changes caused by block damage. ; A miniature sensing and monitoring network is embedded at the bottom of the simulated smart surface layer, including features for data collection. The device consists of a micro-electrode grid, a temperature sensor, piezoelectric fibers, and fiber optic grating sensors. The electrode grid uses copper electrodes (10mm×10mm×0.5mm) and is laid out using resistive tomography technology. The electrode spacing is 5cm. The temperature sensors are micro thermistors, and there are 5 temperature sensors in total. The laboratory intelligent control terminal includes a data acquisition system and computer-based control software. The terminal is electrically connected to a miniature induction monitoring network for receiving data. The signal is sent and a repair trigger command is output according to a preset threshold. The repair activation unit is a small infrared heating lamp, which activates the shape memory fiber in the self-repair unit to realize the autonomous repair simulation of block cracks.

[0060] The test was conducted using the following experimental method: S1: First, add P·O 52.5R cement to a planetary mixer, add deionized water, and stir at 1500 rpm for 10 minutes; then add multi-walled carbon nanotubes and short-cut carbon fibers, and continue stirring at the same speed for 20 minutes; after cooling to 25°C, add microcapsule repair agent and shape memory polymer fiber, and stir at 100 rpm for 8 minutes to finally obtain a uniform intelligent road surface material slurry.

[0061] S2: A copper electrode grid is laid out at 5cm intervals within a laboratory mold (500mm×300mm×100mm). Five miniature thermistors are embedded at the electrode nodes. The leads of the sensors and electrodes are led to the outside through pre-drilled holes in the mold. The intelligent pavement material slurry is poured into the mold, compacted by vibration on a vibrating table, cured at room temperature (25℃) for 24 hours, demolded, and then placed in a standard curing chamber (temperature 20℃, humidity 95%) for 28 days to obtain a cement-based block simulated pavement test specimen.

[0062] S3: Connect the microelectrode grid and the thermistor leads to the data acquisition system, and set the acquisition parameters: resistance signal sampling frequency of 20Hz and temperature signal sampling frequency of 5Hz. Connect the data acquisition system to the computer control software via a data cable, complete communication debugging, and ensure that data can be uploaded to the software in real time.

[0063] S4: A three-point bending test device is used to apply load to cement-based masonry blocks, pre-inducing micro-cracks to simulate pavement damage. When micro-cracks appear in the blocks, the three-dimensional conductive network formed by the self-sensing units is disrupted, causing a change in local resistivity. The micro-electrode grid converts the resistivity change signal into a voltage signal, which is transmitted to the data acquisition system. Thermistors collect the block temperature signal in real time. All signals are converted from analog to digital by the data acquisition system and uploaded to the computer control software once per second. The computer control software has a built-in signal processing algorithm. First, temperature compensation is performed on the uploaded resistivity signal. The compensation formula is:

[0064] In the formula, To compensate for the resistivity, For measured resistivity, The temperature coefficient of chopped carbon fiber is taken as 0.0004 / ℃. For actual measured temperature, The reference temperature is 25℃.

[0065] The relative resistivity change signal was then calculated. , This is the reference resistivity when the blocks are undamaged. The platform's preset trigger threshold is... ≥20%, when calculated in real time When the threshold is reached or exceeded, the computer-controlled software determines that the block has cracks that need repair and immediately sends a repair trigger command; if If the percentage is less than 20%, then we will continue to monitor it in real time.

[0066] Upon receiving the repair trigger command, the researchers activated a small infrared heating lamp to locally heat the damaged area of ​​the masonry block, raising the temperature to 75°C. When the temperature reached 75°C, the shape memory polymer fibers contracted and deformed, mechanically closing the cracks in the block. Simultaneously, the mechanical stress generated by the crack propagation caused the polyurethane shell of the microcapsule repair agent to rupture, allowing the asphalt recycling agent and mineral cementitious agent within the core to flow and gel at the crack, filling the gaps. The synergistic effect of physical and chemical repair achieved a self-healing simulation of the block cracks. After the repair was completed, the infrared heating lamp stopped working, and the block naturally cooled to room temperature.

[0067] Twelve hours after the repair was completed, the computer-controlled software collected the resistivity of the blocks again and found... A decrease to below 5% indicates that the block's self-sensing and self-repair mechanism has been successfully implemented.

[0068] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A material for intelligent road surfaces, characterized in that, It includes a mixture of matrix binder, self-sensing unit and self-healing unit; The matrix binder is either asphalt-based or cement-based. The mass of the self-sensing unit is 0.3% to 1.5% of the mass of the matrix binder, and the self-sensing unit is selected from at least one of carbon-based nanomaterials and short-cut carbon fibers; The self-healing unit includes a microcapsule repair agent and shape memory fibers. The mass of the microcapsule repair agent is 3% to 8% of the mass of the matrix binder, and the mass of the shape memory fibers is 0.1% to 0.6% of the mass of the matrix binder.

2. The intelligent road surface material as described in claim 1, characterized in that, The core of the microcapsule repair agent contains asphalt rejuvenator or epoxy resin.

3. The intelligent road surface material as described in claim 1, characterized in that, Shape memory fibers are shape memory polymer fibers or shape memory alloy fibers, and the activation temperature range of shape memory fibers is 50℃~80℃.

4. A self-sensing and self-healing intelligent road surface, characterized in that, This includes a smart surface layer, a sensor monitoring network, and a smart control system; The intelligent surface layer is constructed from the intelligent pavement material as described in claim 1. A self-sensing unit forms a three-dimensional conductive network within the matrix binder, used to output signals indicating relative resistivity changes caused by pavement damage. ; The sensing and monitoring network is embedded in or beneath the smart surface layer, including features for data collection. Electrode grids and temperature sensors; The intelligent control system is electrically connected to an induction monitoring network for receiving signals. The signal is sent, and a repair trigger command is output according to a preset threshold. The repair activation unit activates the shape memory fibers in the self-repair unit to achieve autonomous repair of the crack.

5. The self-sensing and self-healing intelligent road surface as described in claim 4, characterized in that, Used for collecting The electrode grid for the signal includes an electrode grid laid out using the four-terminal method or electrical impedance tomography technique, with an electrode spacing of 5cm to 10cm.

6. The self-sensing and self-healing intelligent road surface as described in claim 4, characterized in that, The sensing monitoring network also includes piezoelectric fiber and / or fiber optic grating sensors for stress monitoring. The piezoelectric fiber and fiber optic grating sensors are embedded in the bottom of the smart surface layer to assist in damage diagnosis.

7. The self-sensing and self-healing intelligent road surface as described in claim 4, characterized in that, The repair activation unit is an electromagnetic induction heating device or an infrared heating device.

8. A method for implementing the self-sensing and self-healing intelligent road surface as described in claim 4, characterized in that, Includes the following steps: S1: Weigh the matrix binder, self-sensing unit and self-healing unit according to the preset formula. First, mix the matrix binder and self-sensing unit evenly at the first temperature and / or the first speed. Then, embed the self-healing unit into the mixture at the second temperature and / or the second speed. S2: Electrode grids and temperature sensors are embedded in the road structure layer, and the materials for the smart road are paved and compacted. S3: Connect the electrode grid and temperature sensor to the data acquisition system, and connect the data acquisition system to the cloud-based intelligent control platform; S4: Intelligent service and active repair. The data acquisition system continuously collects signals. When the signal reaches the preset trigger threshold, the repair activation unit is automatically activated to perform local repair on the damaged area.

9. The implementation method of a self-sensing and self-repairing intelligent road surface as described in claim 8, characterized in that, In S1, the first temperature is 150~170℃, and the second temperature is below 40℃.

10. The implementation method of a self-sensing and self-repairing intelligent road surface as described in claim 8, characterized in that, In S1, the first speed is 1500~3000rpm, and the second speed is 100~300rpm.

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