Old road composite disease layered repair and asphalt paving integrated process

Abstract

The invention relates to the technical field of road engineering, and discloses an old road composite disease layered repair and asphalt paving integrated process which comprises the following steps: carrying out layered targeted repair on old road diseases; carrying out synergistic enhancement treatment on a repair interface, namely arranging a high-elasticity polyurethane and asphalt stress absorption layer at a construction joint of the new and old plates, and carrying out mechanical micro grooving on the surface of a grouting area; evaluating a representative deflection value of the repaired pavement by using a drop weight deflectometer, and dynamically matching an asphalt paving structure scheme; after the glass fiber grating is laid, the matching scheme is executed. According to the composite pavement structure disclosed by the invention, a synergistic enhancement interface comprising the stress absorption layer and the micro-carving grooves is arranged between the repaired base layer and the asphalt surface layer. According to the method, the quantitative feedback relationship between the repairing effect and the paving design is established, and the systematicness and accuracy of the repairing project are improved by cooperatively enhancing the interface to inhibit the reflection crack.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of road engineering, in particular to an old road composite disease layered repair and asphalt overlay integrated process. BACKGROUND

[0002] In the field of road engineering, overlaying an asphalt cover layer on an old cement concrete pavement is a common maintenance and upgrading technology. However, due to the significant differences in physical and mechanical properties between cement concrete slabs and asphalt mixtures, the joint displacement and slab bottom deformation caused by temperature changes and driving loads on the old cement slabs will concentrate stress at the bottom of the asphalt cover layer and gradually extend to the road surface, forming reflection cracks corresponding to the positions of the lower joints or cracks. Reflection cracks are one of the main reasons for the premature failure of such composite pavement structures.

[0003] In order to suppress the generation of reflection cracks, the prior art usually performs a series of pretreatments on the old cement concrete pavement before asphalt overlay, such as replacing broken slabs, pressure grouting filling in the void area, and laying geogrids or stress absorbing layers as intermediate layer materials on the top surface of the old slabs. These measures can delay the appearance of reflection cracks to some extent.

[0004] However, the prior art has inherent limitations in process implementation. On the one hand, the structural design of the asphalt overlay layer (such as thickness and material type) is usually determined in advance based on the evaluation of the initial condition of the old road, and this design remains unchanged throughout the repair construction process. This approach ignores the actual improvement effect of the pretreatment measures (such as grouting and slab replacement) on the bearing capacity of the old road base. Due to the variability of construction, the actual mechanical state of the repaired base often deviates from the estimated value at the design time, and the fixed overlay scheme cannot be adaptively adjusted according to this actual state, which may result in strength redundancy or deficiency in the final pavement structure.

[0005] On the other hand, the application of interlayer treatment measures in the prior art often lacks pertinence and synergy. For example, a single geogrid or stress absorbing layer is used to treat the entire pavement without differentiation, which fails to effectively distinguish between high stress concentration areas such as new and old concrete construction joints and ordinary grouted slab surfaces in terms of stress state and interface bonding requirements, resulting in insufficient adaptability of the interface treatment measures to complex stress environments, and limiting the comprehensive effectiveness of the measures in suppressing reflection cracks. Therefore, the existing repair process is a combination of multiple independent procedures, lacking a complete technical system that systematically associates and dynamically feeds back base repair, interface treatment, and surface layer design. SUMMARY

[0006] The purpose of the present application is to provide an old road composite disease layered repair and asphalt overlay integrated process, which solves the problem that in the existing old road repair process, due to the lack of quantitative evaluation and feedback on the mechanical state of the repaired base, the asphalt overlay scheme and the interface treatment measures cannot be matched, thereby affecting the overall performance of the composite pavement structure after repair.

[0007] To achieve the above purpose, the present application is implemented by the following technical scheme: an old road composite disease layered repair and asphalt overlay integrated process, comprising the following steps: S1, disease treatment is performed on the old road pavement, and the disease treatment includes replacing broken plates and cement grouting treatment for subsidence and voids; S2, after completing the disease treatment on the old road pavement, the interfaces of different types of repair areas are differentially treated, and the treatment includes: for the new and old concrete plate construction joints formed after replacing the broken plates, a layer of high-elasticity polyurethane and asphalt stress absorption material with a thickness of 1.5-2.5 mm is brushed above the new and old concrete plate construction joints, and for the surface of the old cement plate above the cement grouting treatment area, mechanical micro-groove treatment with a depth of 1.5-3.0 mm and a width of 2.0-4.0 mm is performed; S3, a falling weight deflectometer is used to detect the pavement after the differential treatment, and a representative deflection value is obtained; according to the representative deflection value, one to-be-executed scheme is dynamically matched and determined from at least two preset asphalt overlay structure schemes; S4, glass fiber grids are laid on the pavement after the differential treatment, and the determined asphalt overlay structure scheme is executed, the asphalt surface layer construction is completed, and thus a composite pavement structure is obtained.

[0008] Preferably, in the step S1, the treatment of replacing the broken plates further includes: After the broken plates are chiseled out, the strength of the base layer below is checked, if the base layer strength is insufficient, 150-160 mm is milled down and backfilled with cement stabilized gravel of the same thickness, and then cement concrete is poured.

[0009] Preferably, in the step S1, the cement grouting treatment for subsidence and voids is specifically: Cement grout with a water-cement ratio of 0.5-0.6 is used for grouting under a pressure of 0.2-0.4 MPa.

[0010] Preferably, in the step S2, the high-elasticity polyurethane and asphalt stress absorption material is prepared by mixing A component and B component on site, wherein: The A component is an isocyanate prepolymer, which is prepared by reacting polyether polyol with diphenyl methane diisocyanate at 75-85℃ for 2.5-3.5 hours; The B component is a curing agent and asphalt blend, which is blended by base asphalt, 1,4-butanediol and dioctyl phthalate; the mass ratio of the A component and the B component mixed on site is 1:2.5-1:3.0.

[0011] Preferably, in the step S3, the dynamic matching is specifically: If the measured deflection value is less than or equal to 22, a standard overlay scheme is matched and selected; If 22 is less than the measured deflection value and less than or equal to 30, a reinforced overlay scheme is matched and selected; The total thickness of the asphalt layer of the reinforced overlay scheme is greater than that of the standard overlay scheme.

[0012] Preferably, in the step S4, when the asphalt surface layer is constructed, the upper layer of the asphalt surface layer is asphalt mastic chip mixture, the middle layer or the lower layer of the asphalt surface layer is medium-grained or coarse-grained asphalt concrete, and temperature control is performed during construction, wherein: the paving temperature of the asphalt mastic chip mixture is not less than 160℃, and the paving temperature of the medium-grained or coarse-grained asphalt concrete is not less than 135℃.

[0013] Preferably, in the step S4, when the asphalt surface layer is constructed, a team composed of not less than two pavers is used for joint paving, and the distance between the front and rear of the team of pavers is 10-30m.

[0014] Preferably, in the step S4, In the compaction operation in the construction of the asphalt surface layer, a three-stage process of initial compaction, recompaction and final compaction is followed.

[0015] Preferably, the composite pavement structure comprises, from bottom to top, in order: (a) a repaired old road base layer; (b) a synergistically reinforced interface layer comprising a high-elasticity polyurethane and asphalt stress-absorbing material layer and a grid-shaped micro-groove, which is arranged on the repaired old road base layer; (c) a glass fiber grid layer arranged on the synergistically reinforced interface layer; (d) an asphalt overlay surface layer arranged on the glass fiber grid layer.

[0016] Preferably, in the composite pavement structure, the repaired old road base layer comprises cement concrete patches and dowels and tie rods arranged in the cement concrete patches in the broken slab replacement area. In summary, the present application has at least one of the following beneficial technical effects: 1.The present application directly links the measured mechanical state of the repaired base layer with the structural design of the asphalt overlay layer by introducing a step of dynamically matching the post-repair bearing capacity evaluation with the overlay scheme, so that the design of the overlay structure is no longer based on pre-assumptions, but is adaptively selected based on the actual post-repair bearing capacity, thereby avoiding the problem of structural redundancy or insufficient strength that may be caused by mismatch between the pre-set scheme and the actual repair effect.

[0017] 2.The present application establishes a direct physical link between the bottom repair measures and the function of the upper fiberglass grid crack prevention system by setting a high-elasticity stress absorption layer at the new-old plate construction joint where stress is prone to concentrate and performing micro-groove processing on the surface of the grouting area that needs to be enhanced, forming a composite crack prevention interface that works synergistically, and achieving the suppression of the generation and expansion of reflection cracks through two different mechanisms of stress dissipation and mechanical interlocking.

[0018] 3.The present application combines layered targeted repair, interface synergistic enhancement, dynamic matching decision, and integrated overlay construction, forming a complete process flow including diagnosis, repair, enhancement, verification, matching, and construction, etc., which integrates multiple processes that may be separated in technology into a systematic whole, improving the process control accuracy and systematization of the entire old road repair project. DETAILED DESCRIPTION

[0019] The sources and specifications of the main raw materials and reagents used in the following examples and comparative examples are as follows, and the reagents not specifically mentioned are commercially available analytical pure or higher grade products.

[0020] P.O 42.5 ordinary portland cement, CAS No.: 65997-15-1.

[0021] Medium sand, CAS No.: 14808-60-7.

[0022] Limestone, CAS No.: 471-34-1.

[0023] Polyether polyol, CAS No.: 9082-00-2.

[0024] Diphenyl methane diisocyanate, CAS No.: 101-68-8.

[0025] 1,4-Butanediol, CAS No.: 110-63-4.

[0026] Dioctyl phthalate, CAS No.: 117-81-7.

[0027] Lignin fiber, CAS No.: 9005-53-2.

[0028] Preparation of high-elasticity polyurethane and asphalt stress absorption material: The high-elasticity polyurethane used in the present application and the asphalt stress absorbing material are a two-component reactive material, which comprises component A (isocyanate prepolymer) and component B (curing agent and asphalt blend). The preparation method is as follows: Synthesis of component A (isocyanate prepolymer): (1) 200 parts by mass of polyether polyol (trade name 330N) was added to a four-necked flask equipped with a mechanical stirrer, a thermometer and a condenser, and stirring was started. The temperature was raised to 110-120°C under a vacuum of 1.0-1.5 kPa and the material was dehydrated for 2 hours.

[0029] (2) The vacuum was stopped and dry nitrogen was introduced for protection. The material was cooled to 80°C.

[0030] (3) Under continuous stirring and nitrogen protection, 52 parts by mass of diphenylmethane diisocyanate (MDI) was added at a constant rate, and the dropping speed was controlled so that the temperature of the system did not exceed 85°C. After the addition was completed, the system was kept at a constant temperature of 80±2°C for 3 hours.

[0031] (4) After the reaction was completed, the heating was stopped and the system was naturally cooled to room temperature. The obtained light yellow transparent viscous liquid was sealed and packaged, which was component A.

[0032] Preparation of component B (curing agent and asphalt blend): (1) 500 parts by mass of 70# grade A road petroleum asphalt was added to a reaction kettle with heating and stirring device, and heated to 135°C to completely melt.

[0033] (2) The stirring was started, and 25 parts by mass of 1,4-butanediol (BDO) and 30 parts by mass of dioctyl phthalate (DOP) were added to the reaction kettle in sequence under continuous stirring.

[0034] (3) The mixture was continuously stirred at a temperature of 135±5°C for 45 minutes until the components were uniformly mixed and a stable black homogeneous liquid was formed.

[0035] (4) The obtained product was discharged and sealed and packaged, which was component B.

[0036] In order to further illustrate the present application, the technical solutions provided by the present application will be described in detail below in conjunction with examples, but the protection scope of the present application should not be limited thereby.

[0037] In the examples and comparative examples described in this part, the C35 cement concrete used is prepared according to the conventional concrete mixing ratio of P.O 42.5 ordinary Portland cement, medium sand and limestone crushed stone; the cement paste used is prepared by P.O 42.5 ordinary Portland cement and water; the AC-20C, AC-25C and other asphalt concrete mixtures used are prepared by using No. 70 A-grade road petroleum asphalt as the asphalt, basalt crushed stone as the aggregate and limestone powder as the filler; the SMA-13 asphalt mastic crushed stone mixture used is prepared by using SBS (I-C) modified asphalt as the asphalt, basalt crushed stone as the aggregate, limestone powder as the filler and adding lignin fiber.

[0038] In the embodiments of the present application, the representative deflection value interval threshold (such as 22, 30 and the like with a unit of 0.01 mm) for dynamic matching is determined based on the requirements for the strength and long-term performance of the roadbed and pavement in the current highway engineering technical standards (for example, the “Highway Asphalt Pavement Design Specification JTG D50”) and combined with a large amount of engineering practice data. Specifically: The interval of the representative deflection value ≤ 22 generally corresponds to the state that the repaired base layer is in good condition and the bearing capacity is close to or reaches the standard of the newly built roadbed. In this state, the standard overlay scheme with balanced structure and cost can meet the performance requirements within the design period.

[0039] The interval of 22 < the representative deflection value ≤ 30 indicates that the repaired base layer has been stabilized, but its overall stiffness is reduced compared to the ideal state. In order to ensure the fatigue cracking resistance of the composite pavement structure under long-term load, a reinforced overlay scheme with a larger total thickness of the asphalt layer must be used to compensate for the insufficient bearing capacity of the base layer.

[0040] The interval of the representative deflection value > 30 indicates that the base layer has a more serious structural strength problem, and even after local repair, its bearing capacity is still low. At this time, the heavy-load reinforced overlay scheme with the highest structural strength must be used to significantly increase the thickness of the high-modulus asphalt layer to bear the main load and prevent the pavement structure from failing in a short period of time.

[0041] It should be noted that the above specific thresholds are examples given for typical highway traffic grades and climate environments. Those skilled in the art can adaptively adjust these thresholds according to the specific engineering project requirements, traffic load grades or local standards, which do not deviate from the core technical ideas disclosed in the present application.

[0042] Example 1-3: Example 1: The embodiment provides an integrated process for layered repair of old road composite diseases and asphalt overlay. The object to be repaired is an old cement concrete pavement with broken and bottom void diseases of cement concrete slab. The repair process is as follows: Layered targeted repair: For broken slab: the completely broken concrete slab body is chiseled out using a hydraulic pick, and cleaned to the top surface of the base. After inspection, the strength of the base structure below meets the requirements. Holes are drilled at the joint of the old slab according to the design requirements and HRB400 grade threaded steel is implanted as a load transfer bar and a pull rod. Then, C35 cement concrete is poured in the area, vibrated and compacted and cured to the specified strength.

[0043] For voided slab: holes are drilled on the concrete slab with void. Cement grout with a water-cement ratio of 0.55 is used for grouting under a constant pressure of 0.3 MPa until the adjacent hole or slab edge spouts, and the filling of the voided area is completed.

[0044] Synergistic reinforcement treatment of repair interface: For new and old concrete slab construction joint: after the strength of the newly poured concrete reaches more than 75% of the design requirement, the A component and the B component prepared in advance are mixed in a mass ratio of 1:3.0 within a width of 200 mm above the construction joint of the new and old concrete slab, and then uniformly brushed to form a layer of high-elasticity polyurethane and asphalt stress absorbing material with a thickness of 2.0 mm.

[0045] For cement grouting treatment area: a special grooving equipment is used to excavate grid-shaped micro-grooves with a depth of 2.0 mm and a width of 3.0 mm on the surface of the old cement slab treated by grouting along the longitudinal and transverse directions, and the groove spacing is 300 mm.

[0046] Evaluation of bearing capacity after repair and dynamic matching of overlay scheme: The pavement after all the above repairs and interface treatments is detected using a falling weight deflectometer (FWD), and the representative deflection value of the section is calculated to be 21 (unit: 0.01 mm). According to the preset dynamic matching scheme, since the representative deflection value is ≤22, the standard overlay scheme is selected and executed.

[0047] Integrated asphalt overlay construction: A layer of bidirectional warp glass fiber grid is fully paved on the top surface of the pavement after the interface treatment. Then, the standard overlay scheme is executed for the construction of the asphalt surface layer.

[0048] Firstly, 40mm thickness of AC-20C medium-grained asphalt concrete is laid as the lower layer. The construction is carried out by using two pavers in echelon for joint paving, one in front and the other following behind on the adjacent lane, with the longitudinal distance between the two pavers kept at 15m. The distance ensures that the edge of the asphalt mixture laid by the former paver still keeps the temperature within the range that can realize good compaction and bonding when the latter paver carries out the adjacent lane paving, thus forming a high-density thermal joint.

[0049] Immediately after the paving operation, the compaction operation is carried out. The compaction operation strictly follows the three-stage process of primary compaction, secondary compaction and final compaction: Primary compaction stage: immediately after the paver, a 12-ton double steel wheel roller is used for stable compaction, with the rolling speed controlled at 2.0km / h and rolled once. At this time, the temperature of the lower layer mixture is controlled between 140℃ and 150℃.

[0050] Secondary compaction stage: after primary compaction, a 25-ton rubber-tired roller is used for main compaction, with the rolling speed controlled at 4.0km / h and rolled 6 times to achieve the target compaction degree. The temperature of the mixture in this stage is controlled between 120℃ and 140℃.

[0051] Final compaction stage: after secondary compaction, when the temperature of the mixture drops to above 90℃, a 12-ton double steel wheel roller (vibration off) is used for the final rolling, with the speed controlled at 3.0km / h and rolled twice to eliminate the wheel marks left by the secondary compaction and ensure the flatness of the pavement.

[0052] After the completion of the lower layer construction, the same echelon paving and three-stage compaction process is used to lay 40mm thickness of SMA-13 asphalt mastic chip mixture as the upper layer, with the paving temperature controlled at not less than 165℃. Finally, the composite pavement structure of this embodiment is obtained.

[0053] Example 2: The process flow of this embodiment is basically the same as that of Example 1, with the main difference being the initial state of the old road disease and the dynamic adjustment triggered thereby.

[0054] Layered targeted repair: For broken slabs: after the broken slabs are chiseled out, it is found through inspection that the top surface of the underlying base layer is loose and has insufficient strength. Therefore, the original base layer is first milled down to a depth of 150mm, and then backfilled with 5% cement stabilized gravel of the same thickness and compacted in layers to a heavy compaction degree of 98%, forming a base strengthening layer. Then, the dowel bar implantation and pouring of C35 cement concrete are carried out.

[0055] For voided slabs: cement grout with a water-cement ratio of 0.6 is used for grouting treatment under a pressure of 0.35MPa.

[0056] Cooperative reinforcement treatment of the repaired interface: The operation of this step is exactly the same as that of Example 1.

[0057] Post-repair bearing capacity evaluation and dynamic matching of overlay scheme: The pavement after repair and interface treatment is detected using a falling weight deflectometer (FWD), and the representative deflection value of the section is calculated to be 26 (unit: 0.01 mm). According to the preset dynamic matching scheme, since 22 < representative deflection value ≤ 30, the reinforced overlay scheme is selected and executed.

[0058] Integrated asphalt overlay construction: On the top surface of the pavement after interface treatment, a layer of bidirectional warp glass fiber grid is fully paved. Then, the reinforced overlay scheme is executed, specifically: AC-25C coarse-grained asphalt concrete with a thickness of 60 mm is laid as the lower layer, and the paving temperature is controlled to be no less than 135°C.

[0059] SMA-13 asphalt mastic chip mixture with a thickness of 40 mm is laid as the upper layer, and the paving temperature is controlled to be no less than 165°C. The echelon paving and three-stage compaction process during construction are the same as those of Example 1. Finally, the composite pavement structure of this example is obtained.

[0060] Example 3: This example provides a repair and overlay process under the condition of serious damage to the base.

[0061] Layered targeted repair: For broken slabs: After the broken slabs are removed, it is found that the base and subbase below have been severely damaged and have lost bearing capacity. Therefore, the original base and subbase are completely removed by excavating 400 mm. Then, the new subbase is backfilled by laying 200 mm thick low-dose cement stabilized gravel (cement content 3%) and the new base is backfilled by laying 200 mm thick cement stabilized gravel (cement content 5%) in sequence. Each structural layer is compacted to a heavy compaction degree of 98%. Then, the dowel bar implantation and C35 cement concrete pouring are performed.

[0062] For voided slabs: cement grout with a water-cement ratio of 0.50 is used for grouting treatment under a pressure of 0.40 MPa.

[0063] Cooperative reinforcement treatment of the repaired interface: The operation of this step is exactly the same as that of Example 1.

[0064] Post-repair bearing capacity evaluation and dynamic matching of overlay scheme: The pavement after repair and interface treatment was detected using a falling weight deflectometer (FWD), and the representative deflection value of the road section was calculated to be 35 (unit: 0.01 mm). According to the preset dynamic matching scheme, since the representative deflection value > 30, the heavy load strengthening overlay scheme was selected and executed.

[0065] Integrated asphalt overlay construction: On the top surface of the pavement after interface treatment, a layer of bidirectional warp glass fiber grid was fully paved. Then, the heavy load strengthening overlay scheme was executed, specifically: An 80 mm thick AC-25C coarse-grained asphalt concrete was laid as the lower layer.

[0066] A 50 mm thick SMA-13 asphalt mastic chip mixture was laid as the upper layer. The echelon paving and three-stage compaction process in construction were all executed according to the detailed method described in step (4) of Example 1. Finally, the composite pavement structure of this example was obtained.

[0067] Comparative Example 1: Compared with Example 1, the difference is that the post-repair bearing capacity evaluation and overlay scheme dynamic matching are not performed, but the pre-designed fixed asphalt overlay scheme (laying a 40 mm thick AC-20C lower layer and a 40 mm thick SMA-13 upper layer) is directly used for construction. The rest are the same.

[0068] Comparative Example 2: Compared with Example 1, the difference is that the cooperative reinforcement treatment of the repair interface is not performed, that is, after completing the layered targeted repair, neither high-elasticity polyurethane nor asphalt stress absorbing material is brushed, and no mechanical micro-grooving treatment is performed on the surface of the cement grouting treatment area, and the subsequent bearing capacity evaluation and overlay construction steps are directly performed. The rest are the same.

[0069] Comparative Example 3: Compared with Example 1, the difference is that when performing the cooperative reinforcement treatment of the repair interface, only the new and old concrete slab construction joints are brushed with high-elasticity polyurethane and asphalt stress absorbing material, and the surface of the cement grouting treatment area is not mechanically micro-grooved. The rest are the same.

[0070] Comparative Example 4: Compared with Example 3, the difference is that when performing the post-repair bearing capacity evaluation and overlay scheme dynamic matching, although the representative deflection value is 35 (> 30), the corresponding heavy load strengthening overlay scheme is not matched and executed, but a standard overlay scheme (laying a 40 mm thick AC-20C lower layer and a 40 mm thick SMA-13 upper layer) is mistakenly executed. The rest are the same.

[0071] Test Example 1: Anti-reflection crack performance evaluation: This test example aims to evaluate the ability of composite pavement structures prepared by different processes to resist the generation and propagation of reflective cracking under simulated temperature cycling and dynamic loading.

[0072] 1. Experimental procedure: (1) Test slab preparation: Composite pavement structure test slabs with dimensions of 500 mm x 300 mm were prepared according to the complete processes described in Example 1, Example 2, Comparative Example 1, Comparative Example 2 and Comparative Example 3, respectively. The lower part of each slab was an old cement concrete slab simulation with a through joint at the center position to simulate the construction joint or potential cracking position of new and old concrete slabs.

[0073] (2) Temperature and load cycling test: The prepared test slabs were placed in an environmental simulation test chamber with dynamic loading function. The following cycling program was set and executed: First, the temperature in the chamber was decreased from 20°C to -10°C, and kept constant for 4 hours; Then, the temperature in the chamber was increased from -10°C to 40°C, and kept constant for 4 hours.

[0074] This process constitutes a complete high-low temperature cycle. During the entire process of each high-low temperature cycle, a dynamic load with a frequency of 10 Hz and a contact pressure of 0.7 MPa was continuously applied through the loading wheel directly above the center joint of the test slab.

[0075] (3) Data collection: After completing 1000 temperature and load cycles as described above, the test slabs were removed from the test chamber. The crack width measuring instrument and ruler were used to measure and record the length of each crack appearing on the asphalt overlay of each slab, and all crack lengths were added to obtain the total crack length of the slab. The total crack length was divided by the surface area of the slab (0.15 m 2 ), to calculate the total crack length per unit area. Three parallel samples were tested for each process, and the results were averaged.

[0076] Test results: The results of the reflective cracking resistance performance test of each group of test slabs are recorded in the table below.

[0077] Table 1. Results of reflective cracking resistance performance test The test data in Table 1 shows that the total length of reflective cracks per unit area of the composite pavement structure prepared according to the processes of Example 1 and Example 2 is significantly lower than that of all the comparative examples. This result directly reflects the role of the integrated process described in the present application in improving the anti-cracking performance of the structure. The process combines layer-by-layer targeted repair, post-repair bearing capacity evaluation, dynamic matching of overlay schemes, and synergistic enhancement treatment of the repair interface to form a complete technical system, so that the final composite pavement structure exhibits stronger resistance to crack development under the combined action of long-term temperature variation and load.

[0078] The comparison of the data of Example 1 with Comparative Example 2 and Comparative Example 3 shows the direct effect of the synergistic enhancement treatment of the repair interface. Compared with Comparative Example 2 (1.42 m / m 2 ) which does not perform any interface treatment, the crack length of Example 1 (0.23 m / m 2 ) is greatly reduced. The mechanism is that the high-elasticity polyurethane and the asphalt stress absorbing material layer arranged at the joint can absorb and dissipate the stress concentration caused by temperature shrinkage and load through its large deformation capacity; at the same time, the mechanical micro-groove arranged on the surface of the grouting area enhances the physical interlocking effect of the asphalt overlay layer and the old plate base layer by increasing the interface roughness, limiting the relative displacement between them. Comparative Example 3 (0.67 m / m 2 ) lacks the micro-groove treatment, and its crack length is between that of Example 1 and Comparative Example 2, which confirms that the synergistic effect of stress absorption and mechanical interlocking is necessary for building an effective composite anti-cracking interface.

[0079] The comparison of the data of Example 1, Example 2, and Example 3 with Comparative Example 1 and Comparative Example 4 systematically reflects the necessity of the steps of post-repair bearing capacity evaluation and dynamic matching of overlay schemes. Example 2 and Example 3 respectively triggered the implementation of a stronger reinforcement overlay scheme and a heavy load reinforcement overlay scheme for the structure according to the representative deflection values measured after repair, and their final anti-cracking performance (0.18 m / m 2 and 0.15 m / m 2 ) is excellent. Comparative Example 4, which has the same initial conditions as Example 3 (both representative deflection values are 35), but due to the incorrect matching of the standard overlay scheme with insufficient strength, its total length of reflective cracks per unit area reaches a disastrous 2.58 m / m 2 , and the structure is rapidly destroyed in the test. This result, which is in sharp contrast to the excellent performance of Example 3, directly and conclusively proves that the quantitative matching of the overlay layer structure design with the measured mechanical state of the repaired base layer is a decisive technical link to ensure that the final composite pavement structure obtains the expected service performance and durability.

[0080] Test Example 2: Interlayer bonding performance evaluation: This test example aims to evaluate the interfacial bond strength between the asphalt overlay and the underlying repaired old cement concrete slab subbase in composite pavement structures prepared by different processes.

[0081] 1. Experimental procedure: (1) Test core preparation: From each group of test slabs prepared in Test Example 1 and having completed the temperature and load cycling tests, cores were drilled using a core drill with a diameter of 100 mm. The drilling locations were chosen in the areas simulated for cement grouting treatment, ensuring that the cores contained the asphalt overlay, the interfacial bond interface, and part of the old cement slab subbase.

[0082] (2) Interfacial shear test: The drilled cores were placed on a universal material testing machine. Using a dedicated shear clamp, the shear force was applied with the plane precisely aligned at the bond interface between the asphalt overlay and the old cement slab subbase.

[0083] (3) Data collection: The testing machine was started to apply the shear load at a loading rate of 5 mm / min until the core failed in shear at the interfacial bond. The peak load P at failure was recorded. The interfacial shear strength τ was calculated according to the formula τ = P / A, where A is the cross-sectional area of the core. Three cores for each process were tested, and the results were averaged.

[0084] 2. Test results: The interfacial shear strength test results for each group of test cores are recorded in the table below.

[0085] Table 2. Interfacial shear strength test results Group Interlaminar shear strength (MPa) Example 1 1.12 Example 2 1.15 Example 3 1.14 Comparative Example 1 1.09 Comparative Example 2 0.47 Comparative Example 3 0.78 Comparative Example 4 1.11 The data in Table 2 objectively shows the effect of different processes on the interfacial bond performance. The structures prepared in Example 1 and Example 2 have significantly higher interfacial shear strength values than Comparative Example 2 and Comparative Example 3. This result indicates that the processes described in the present invention, particularly the synergistic reinforcement treatment step regarding the repair interface, effectively enhance the bonding ability between the asphalt overlay and the repaired old slab subbase, thereby forming a more integrated composite structure.

[0086] The test results of Example 1 and Comparative Examples 2 and 3 directly reveal the mechanism of the technical features in the interface synergistic reinforcement treatment. Comparative Example 2 does not have any interface treatment, and its interlayer shear strength is the lowest (0.47 MPa), which only relies on the bonding effect of the tack coat asphalt. Comparative Example 3 has a coating of high-elastic polyurethane and asphalt stress absorbing material (the area is actually tack coat asphalt) without micro-grooving treatment, and its strength (0.78 MPa) is increased. However, the strength (1.12 MPa) of Example 1, which includes micro-grooving treatment, is the highest. The differences in the data confirm that the mechanical micro-grooving treatment with controlled depth and width on the surface of the cement grouting area provides physical interlocking space for the subsequent asphalt material by increasing the surface area and roughness of the interface, forming significant mechanical gripping force. The mechanical interlocking effect is one of the main sources of interlayer bonding strength.

[0087] Comparing the test results of Comparative Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 4, it can be observed that their interlayer shear strength values are all at a relatively high level of 1.09 MPa to 1.15 MPa and close to each other. This indicates that the interlayer bonding performance is mainly determined by the interface treatment process itself, and has no direct correlation with the specific structure scheme (standard, strengthened or heavy-duty strengthening scheme) of the upper asphalt overlay and the selection method (dynamic matching or error matching) of the scheme. This phenomenon further illustrates that the repair interface synergistic reinforcement treatment described in the present application is an independent and stable technical module, which can stably provide high-level interlayer bonding strength under different overlay structures, and dynamic matching is the key step to ensure that the upper structure can adapt to the state of the base on this basis, and the two together constitute the complete technical system of the present application.

Claims

1. An integrated process for layered repair and asphalt overlay of complex road defects, characterized in that: Includes the following steps: S1. Treat the defects of the old road surface, including replacing broken slabs and grouting the subsidence and voids with cement. S2. After completing the treatment of defects in the old road surface, differentiated treatment is applied to the interfaces of different types of repair areas. This treatment includes: For the construction joint between the old and new concrete slabs formed after the replacement of the broken slab, a layer of high-elasticity polyurethane and asphalt stress-absorbing material with a thickness of 1.5-2.5mm is applied above the construction joint between the old and new concrete slabs. For the surface of the old cement slab above the cement grouting treatment area, mechanical micro-grooving treatment with a depth of 1.5-3.0mm and a width of 2.0-4.0mm is performed. S3. Use a falling weight deflectometer to test the pavement after the differential treatment and obtain a representative deflection value; based on the representative deflection value, dynamically match and determine a scheme to be executed from at least two preset asphalt overlay structure schemes. S4. Lay fiberglass grids on the differentiated road surface and implement the determined asphalt overlay structure scheme to complete the asphalt surface layer construction and thereby obtain a composite road structure.

2. The integrated process of layered repair and asphalt overlay for composite road defects as described in claim 1, characterized in that, In step S1, the process of replacing the broken plate further includes: After removing the broken slab, check the strength of the base layer underneath. If the base layer is not strong enough, mill downwards 150-160mm and backfill with cement-stabilized crushed stone of equal thickness, and then pour cement concrete.

3. The integrated process of layered repair and asphalt overlay for composite road defects as described in claim 1, characterized in that, In step S1, the cement grouting treatment for subsidence and voids specifically involves: Cement paste with a water-cement ratio of 0.5-0.6 is used for grouting under a pressure of 0.2-0.4 MPa.

4. The integrated process of layered repair and asphalt overlay for composite road defects as described in claim 1, characterized in that, In step S2, the highly elastic polyurethane and asphalt stress-absorbing material is prepared by on-site mixing of component A and component B, wherein: Component A is an isocyanate prepolymer, prepared by reacting polyether polyol with diphenylmethane diisocyanate at 75-85°C for 2.5-3.5 hours; Component B is a blend of curing agent and asphalt, which is composed of base asphalt, 1,4-butanediol and dioctyl phthalate. The mass ratio of component A to component B mixed on-site is 1:2.5-1:3.

0.

5. The integrated process of layered repair and asphalt overlay for composite road defects as described in claim 1, characterized in that, In step S3, the dynamic matching specifically refers to: Pre-set at least two sequentially increasing representative deflection value intervals, and pre-set a corresponding asphalt overlay scheme for each interval; The total thickness of the asphalt layer in the various asphalt overlay schemes increases as the corresponding representative deflection value range increases.

6. The integrated process of layered repair and asphalt overlay for composite road defects as described in claim 1, characterized in that, In step S4 When performing the asphalt surface layer construction, the upper layer of the asphalt surface layer is an asphalt mastic aggregate mixture, and the middle or lower layer of the asphalt surface layer is a medium-grained or coarse-grained asphalt concrete. Temperature control is carried out during construction, wherein the paving temperature of the asphalt mastic aggregate mixture is not lower than 160℃, and the paving temperature of the medium-grained or coarse-grained asphalt concrete is not lower than 135℃.

7. The integrated process of layered repair and asphalt overlay for composite road defects as described in claim 5, characterized in that, In step S4 During asphalt pavement construction, no fewer than two pavers shall be used to form a team for joint paving, with the distance between the front and rear of the team of pavers being 10-30m.

8. The integrated process of layered repair and asphalt overlay for composite road defects as described in claim 6, characterized in that, In step S4 The compaction process in asphalt pavement construction follows a three-stage process: initial compaction, intermediate compaction, and final compaction.

9. The integrated process of layered repair and asphalt overlay for composite road defects as described in claim 1, characterized in that, The composite pavement structure, from bottom to top, includes: (a) The restored base course of the old road; (b) A synergistically reinforced interface layer disposed on the repaired old road base course and comprising a layer of highly elastic polyurethane and asphalt stress-absorbing material and a grid-like microgroove. (c) A fiberglass grid layer disposed on the synergistic reinforcement interface layer; (d) An asphalt overlay layer disposed on the fiberglass grid layer.

10. The integrated process of layered repair and asphalt overlay for composite road defects as described in claim 1, characterized in that, In the composite pavement structure, the repaired old road base includes cement concrete patches and dowel bars and tie bars installed in the cement concrete patches in the area where the broken slabs are replaced.

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