Method for determining optimal spraying time of road penetration layer and seal layer integration

Abstract

The application discloses a method for determining the optimal spraying time of a road penetration layer and a sealing layer, comprising the following steps: preparing semi-rigid base mixture according to design requirements and laying the semi-rigid base; preparing penetration layer material and sealing layer material according to design requirements respectively and laying the penetration layer and the sealing layer; preparing asphalt sub-base mixture according to design requirements and laying the asphalt sub-base; preparing shear test pieces on the semi-rigid base asphalt pavement formed by spraying the penetration layer and the sealing layer with different spraying time combinations, and performing shear tests respectively, and performing multi-stage verification on the shear test results, so as to determine the optimal spraying time combination of the road penetration layer and the sealing layer. The application can accurately determine the optimal spraying time combination of the penetration layer and the sealing layer, improve construction efficiency and reduce maintenance cost. The determined spraying time combination of the penetration layer and the sealing layer will not cause the semi-rigid base to crack, the interlayer adhesion between the semi-rigid base and the asphalt sub-base is firm enough, and the service life of the road is improved.

Description

Technical Field

[0001] This invention belongs to the field of road engineering technology, specifically relating to a method for determining the optimal timing for the integrated application of road permeable and sealing coats. Background Technology

[0002] With the successful implementation and continuous advancement of the national strategy to build a strong transportation network, transportation infrastructure construction has developed rapidly. In my country's asphalt pavement construction, over 90% of the pavements are semi-rigid base asphalt pavements, which is the most important pavement structure type in my country and plays a crucial role in road construction. In semi-rigid base asphalt pavement structures, a tack coat and a seal coat are placed between the asphalt pavement and the semi-rigid base. The seal coat is placed on top of the tack coat, and both the tack coat and seal coat are relatively thin, usually combined into a single tack-seal coat. However, it is undeniable that with the rapid development of the transportation industry, my country's traffic volume has increased dramatically, and vehicle overloading and overweight phenomena have become increasingly frequent. This phenomenon has brought severe challenges to semi-rigid base asphalt pavements, leading to increased shear stress between the asphalt pavement and the semi-rigid base, resulting in increasingly serious interlayer slippage defects.

[0003] Good interlayer bonding effectively distributes traffic loads across the pavement, improving road performance and delaying the onset of pavement defects. Conversely, poor interlayer bonding increases tensile stress and strain at the base of each layer, leading to pavement defects and reduced service life. Good interlayer bonding requires not only high-quality materials but also meticulous attention to construction quality and precise timing of application.

[0004] Extensive literature review and field surveys revealed that there is currently no precise combination of application times for tack coat and seal coat during on-site construction. This not only leads to problems such as cracking of the semi-rigid base layer itself and insufficient bonding between the semi-rigid base layer and the asphalt pavement, but also significantly increases subsequent road maintenance and repair costs, which is detrimental to subsequent cost control and the long service life of the road.

[0005] The interlayer bonding performance and benefits resulting from different application times of tack coat and seal coat vary greatly. However, the current technology has not recorded the optimal application time for tack coat and seal coat, and the specifications do not clearly stipulate the application time for tack coat and seal coat. Therefore, determining the optimal construction time for functional layers with good interlayer bonding performance is an important and urgent need in road construction. It is currently necessary to develop a method for determining the optimal application time of integrated tack coat and seal coat for roads, in order to solve the problems existing in the current technology, and thus provide a theoretical basis and practical reference for the revision of specifications.

[0006] The invention patent application with publication number CN105386382A discloses a construction method for a fiber-reinforced lower seal layer of a semi-rigid base asphalt pavement. During construction, a lower layer of emulsified asphalt, an intermediate layer of alkali-free glass fiber, and an upper layer of emulsified asphalt are applied to the surface of the semi-rigid base. The spraying rates of the lower and upper emulsified asphalt layers are controlled at 0.65-0.75 kg / m³, respectively. 2 and 0.55-0.68 kg / m 2 The amount of alkali-free glass fiber spread in the intermediate layer is controlled to be no less than 60g / m according to different highway grades. 2 Crushed stone aggregate should be spread immediately after emulsified asphalt spraying and alkali-free glass fiber spreading. The spreading action should be completed within 1-2 minutes after the emulsified asphalt spraying and alkali-free glass fiber spreading, and the amount of crushed stone aggregate spread should be controlled at 6.5-7.5 m³. 3 / km 2 The technical solution limits the spraying amount of the lower and upper emulsified asphalt layers, as well as the spraying time and amount of the crushed stone aggregate. However, it does not limit the spraying timing of the lower and upper emulsified asphalt layers, meaning the spraying timing of the prime coat and seal coat is unclear. This not only leads to problems such as cracking of the semi-rigid base itself and insufficient bonding between the semi-rigid base and the asphalt pavement, but also significantly increases subsequent road maintenance and repair costs. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a method for determining the optimal timing for the integrated application of road priming and sealing coats, comprising the following steps in sequence:

[0008] Step 1: Prepare the semi-rigid base course mixture according to the design requirements, and lay the semi-rigid base course mixture according to the relevant technical requirements of "Technical Details for Construction of Highway Pavement Base Course" to form the semi-rigid base course of the road.

[0009] Step 2: Prepare the tack coat and seal coat materials according to the design requirements, and apply them sequentially to the upper surface of the semi-rigid base layer according to the designed application timing to form the tack coat and seal coat of the road.

[0010] Step 3: Prepare the asphalt base course mixture according to the design requirements, and lay the asphalt base course mixture on the upper surface of the sealing layer according to the relevant technical requirements of the "Technical Specification for Construction of Highway Asphalt Pavement" to form the asphalt base course of the road;

[0011] Step 4: After the semi-rigid base course, tack coat, seal coat, and asphalt base course are laid in sequence, a semi-rigid base asphalt pavement for shear testing is formed. Shear specimens are prepared on the semi-rigid base asphalt pavement formed by applying the tack coat and seal coat at different application times, and shear tests are conducted separately. At the same time, the shear test results are verified at multiple levels to determine the optimal application time for the integrated application of the tack coat and seal coat.

[0012] Preferably, in step one, the semi-rigid base mixture is composed of mineral aggregate, cement, and water, wherein the cement content is 5.0 wt% of the mineral aggregate, and the water content is 5.1 wt% of the mineral aggregate; the mineral aggregate is composed of limestone with a particle size of 20-30 mm, limestone with a particle size of 10-20 mm, limestone with a particle size of 5-10 mm, and manufactured sand with a particle size of 0-5 mm, wherein the limestone with a particle size of 20-30 mm, limestone with a particle size of 10-20 mm, limestone with a particle size of 5-10 mm, and manufactured sand with a particle size of 0-5 mm account for 20 wt%, 34 wt%, 16 wt%, and 30 wt% of the mineral aggregate, respectively; and the laying thickness of the semi-rigid base is 20-40 cm.

[0013] Step 1 involves limestone with a particle size of 20-30mm, limestone with a particle size of 10-20mm, limestone with a particle size of 5-10mm, and manufactured sand with a particle size of 0-5mm. Within each particle size range, there may be raw materials with different particle sizes. For example, limestone with a particle size of 20-30mm is limestone material obtained by passing limestone material through a 30mm sieve and a 20mm sieve in sequence, resulting in limestone material with a particle size between 20-30mm.

[0014] In any of the above embodiments, it is preferred that, in step two, the tack coat material is PC-2 emulsified asphalt, and the application rate of the tack coat is 0.8-1.2 L / m. 2 .

[0015] In any of the above embodiments, preferably, in step two, the seal material is composed of manufactured sand, BC-1 emulsified asphalt, and water, wherein the amount of BC-1 emulsified asphalt added is 13.4 wt% of the manufactured sand, and the amount of water added is 15.0 wt% of the manufactured sand; the manufactured sand is composed of manufactured sand with a particle size of 0-0.6 mm, manufactured sand with a particle size of 0.6-1.18 mm, manufactured sand with a particle size of 1.18-2.36 mm, and manufactured sand with a particle size of 2.36-4.75 mm, wherein the manufactured sand with a particle size of 0-0.6 mm, 0.6-1.18 mm, 1.18-2.36 mm, and 2.36-4.75 mm account for 39 wt%, 20 wt%, 26 wt%, and 15 wt% of the total mass of the manufactured sand, respectively; and the thickness of the seal layer is 6-10 mm.

[0016] Step two involves manufactured sand with particle sizes of 0-0.6mm, 0.6-1.18mm, 1.18-2.36mm, and 2.36-4.75mm. Within each particle size range, there may be raw materials with different particle sizes. For example, manufactured sand with a particle size of 2.36-4.75mm is manufactured sand material with a particle size between 2.36-4.75mm obtained by passing the manufactured sand material through a 4.75mm sieve and a 2.36mm sieve in sequence.

[0017] In any of the above schemes, it is preferred that, in step two, at least thirty combinations of application timing for the priming layer and the sealing layer are designed, wherein the application timing range for the priming layer is 0-28 days, and the application timing range for the sealing layer is 0-28 days, where day 0 is the day the semi-rigid base layer is laid, and a day is calculated as 24 hours.

[0018] In any of the above embodiments, preferably, in step three, the asphalt lower layer mixture consists of aggregate and asphalt, and the amount of asphalt added is 4.0 wt% of the aggregate; the aggregate consists of limestone with a particle size of 22-30 mm, limestone with a particle size of 16-22 mm, limestone with a particle size of 12-16 mm, limestone with a particle size of 6-12 mm, limestone with a particle size of 3-6 mm, manufactured sand with a particle size of 0-3 mm, mineral powder, and quicklime, wherein the aggregate with a particle size of 22 mm is... The mass percentages of the following aggregates are as follows: limestone with a particle size of -30mm, limestone with a particle size of 16-22mm, limestone with a particle size of 12-16mm, limestone with a particle size of 6-12mm, limestone with a particle size of 3-6mm, manufactured sand with a particle size of 0-3mm, mineral powder, and quicklime, respectively, are 15wt%, 15wt%, 19wt%, 20wt%, 6wt%, 22wt%, 2wt%, and 1wt%; the thickness of the asphalt sublayer is 3-5cm.

[0019] Step 3 involves limestone with particle sizes of 22-30mm, 16-22mm, 12-16mm, 6-12mm, 3-6mm, and 0-3mm manufactured sand. Within each particle size range, there may be raw materials with different particle sizes. For example, limestone with a particle size of 22-30mm is limestone material with a particle size between 22-30mm obtained by passing limestone material through a 30mm sieve and a 22mm sieve in sequence.

[0020] In any of the above schemes, the preferred method is that, in step four, shear tests are conducted on shear specimens of semi-rigid base asphalt pavement with tack coat and seal coat applied at different times, and the shear test results are verified at multiple levels. This method includes the following steps in sequence:

[0021] Step A: Conduct shear tests on shear specimens with different spraying timing combinations to obtain the relationship curves between interlayer shear force and shear displacement, and convert the relationship curves between interlayer shear force and shear displacement into the relationship curves between interlayer shear stress and shear displacement; Step B: Find the maximum interlayer shear stress on each relationship curve between interlayer shear stress and shear displacement, and then sort each maximum interlayer shear stress by magnitude. The spraying timing combination corresponding to the largest maximum interlayer shear stress is taken as the initial optimal spraying timing for integrated penetration and sealing layers.

[0022] Step C: Perform the first-level verification of the shear test results, that is, use the interlaminar shear modulus model to calculate the interlaminar shear modulus of the shear specimens with different spraying timing combinations, and then sort each interlaminar shear modulus by size.

[0023] Step D: Perform a second-level verification of the shear test results, that is, find the maximum slope of each interlaminar shear stress versus shear displacement curve, take the maximum slope as the maximum stiffness of the shear specimen, and then sort each maximum stiffness by size.

[0024] Step E: Perform third-level verification of the shear test results. That is, on each interlaminar shear stress versus shear displacement curve, draw a vertical line from the point corresponding to the maximum interlaminar shear stress to the horizontal axis, and at the same time draw a diagonal line from the point corresponding to the maximum interlaminar shear stress. This diagonal line is parallel to the secant line corresponding to the maximum slope on the curve. At this time, the diagonal line divides the area enclosed by the curve and the vertical line into left and right parts. Then, sort the area of ​​the left region in each curve by size, and sort the ratio of the area of ​​the left region to the area of ​​the right region in each curve by size.

[0025] Step F: If the shear specimen corresponding to the largest interlaminar shear stress has the largest interlaminar shear modulus, maximum stiffness, left area, and ratio of left area to right area, then the spraying timing combination corresponding to the shear specimen with the largest interlaminar shear stress is taken as the optimal spraying timing for the final integrated permeation and seal coat. Otherwise, for the third-level verification, the ranking of the left area and the ratio of left area to right area needs to be considered comprehensively, and the spraying timing combination corresponding to the shear specimen with the largest comprehensive ranking is taken as the optimal spraying timing for the final integrated permeation and seal coat.

[0026] Preferably, in any of the above schemes, in step C, the interlaminar shear modulus model is: In the formula,

[0027] E d — Interlaminar shear modulus, in MPa / mm;

[0028] τ max —Maximum inter-story shear stress, in MPa;

[0029] S1—Shear displacement corresponding to 0.2 times the maximum inter-story shear stress, in mm;

[0030] S2 — Shear displacement corresponding to 0.8 times the maximum inter-layer shear stress, in mm.

[0031] In this invention, the interlayer shear modulus refers to the shear stress generated at the interface when the upper and lower pavement layers undergo a unit relative displacement. The interlayer bond state is evaluated using the interlayer shear modulus: a larger interlayer shear modulus value indicates better interlayer bond performance and a more complete interlayer continuity; a smaller interlayer shear modulus value indicates poorer interlayer bond performance and a greater tendency for interlayer slippage.

[0032] In any of the above schemes, preferably, in step E, the area of ​​the left-side region represents the energy required for interlayer failure. The larger the area of ​​the left-side region, the more difficult the interlayer failure is, and the better the bonding performance of the pass-through layer and the seal layer. The area of ​​the right-side region represents the energy lost during the interlayer failure process. The smaller the area of ​​the right-side region, the less ineffective work is done during the interlayer failure process.

[0033] In this invention, the region enclosed by the inclined line passing through the maximum shear stress and the vertical line passing through the maximum shear stress is divided into left and right parts. The interlayer adhesion performance of the shear specimen is further evaluated by the ratio of the area of ​​the left region to the area of ​​the right region. The area of ​​the left region is crucial; the larger the area of ​​the left region, the better the adhesion performance of the primer and the seal coat, thus determining the optimal timing for integrated application of the primer and the seal coat. In this invention, the primer and the seal coat are applied separately, according to their respective application times; however, they are integrated during the shear test and the determination of the optimal application time is also integrated. The application times of the primer and the seal coat are mutually constrained, ultimately forming the optimal combination of application times.

[0034] In any of the above schemes, the preferred method is that, in step F, the optimal timing for the integrated application of the priming and sealing layers is determined to be that the application time interval between the priming and sealing layers is 0.5-1.5 days, and the application timing for the priming layer is 6-8 days and the application timing for the sealing layer is 7-9 days.

[0035] In this invention, roads include highways and urban roads, with highways being the primary focus. There are three sources for shear specimens: First, the road surface is laid on-site, and shear tests are conducted on-site using the equipment described in application number 202111145668.1, entitled "A Testing Machine and Test Method for Measuring the Interlayer Shear Strength of Roads"; second, the road surface is laid on-site, and shear specimens are prepared on-site, then brought back to the laboratory for shear tests using the equipment described in application number 202211163381.6, entitled "A Testing Machine and Test Method for Indoor Measurement of Interlayer Shear Strength of Roads," or using... The first method involves using the equipment described in application number 202310979966.3, entitled "Testing Machine and Test Method for Indoor and Outdoor Measurement of Road Interlayer Shear Strength"; the second method involves preparing shear specimens in the laboratory and conducting shear tests thereon, using the equipment described in application number 202211163381.6, entitled "Testing Machine and Test Method for Indoor Measurement of Road Interlayer Shear Strength", or the equipment described in application number 202310979966.3, entitled "Testing Machine and Test Method for Indoor and Outdoor Measurement of Road Interlayer Shear Strength". For all three methods, existing shearing equipment can also be used. Regardless of the type of shearing equipment used, the optimal timing for the integrated application of the tack coat and seal coat can be determined by following the technical solution described in this invention.

[0036] The limestone, manufactured sand, mineral powder, quicklime, and cement used in the preparation of the semi-rigid base course, prime coat, seal coat, and asphalt base course are sourced from Shandong Huitai Mining Co., Ltd., while the asphalt and emulsified asphalt are sourced from Shandong Expressway Materials Group Co., Ltd. The raw material ratios for the semi-rigid base course, prime coat, seal coat, and asphalt base course are important, but there are no special restrictions on the mixing process, cement type, asphalt type, mineral powder particle size, or quicklime particle size.

[0037] The method for determining the optimal application time of the integrated road tack coat and seal coat of the present invention can accurately determine the optimal application time combination of the tack coat and seal coat, improve construction efficiency, and reduce maintenance costs. The application time combination of the tack coat and seal coat determined by the method of the present invention will not cause cracking of the semi-rigid base layer, and the interlayer adhesion between the semi-rigid base layer and the asphalt pavement is strong enough, thereby improving the service life of the road. At the same time, it also lays the foundation for the revision of specifications. Attached Figure Description

[0038] Figure 1 A flowchart of a preferred embodiment of the method for determining the optimal application time of the integrated road surface primer and sealer according to the present invention;

[0039] Figure 2 for Figure 1 Construction photos of the application of the tack coat and seal coat in the illustrated embodiment;

[0040] Figure 3 for Figure 1 A photograph of the actual shear specimen prepared on-site in the illustrated embodiment;

[0041] Figure 4 for Figure 1 Photographs of the shearing test process in the illustrated embodiment;

[0042] Figure 5 for Figure 1 The graph shows the relationship between interlayer shear stress and shear displacement of the shear specimen with the optimal combination of application timing for the tack coat and seal coat in the illustrated embodiment.

[0043] Figure 6 for Figure 1 The secant diagram corresponding to the maximum stiffness of the shear specimen in the embodiment with the optimal combination of spraying timing for the tack coat and the seal coat.

[0044] Figure 7 for Figure 1 The diagram shows the area division of the left and right regions in the curve of interlayer shear stress versus shear displacement of the shear specimen with the optimal combination of application timing for the tack coat and the seal coat in the illustrated embodiment. Detailed Implementation

[0045] To further understand the invention, the following detailed description of the invention will be provided in conjunction with specific embodiments.

[0046] like Figure 1 As shown, a preferred embodiment of the method for determining the optimal application time of the integrated road surface primer and sealer according to the present invention includes the following steps in sequence:

[0047] Step 1: Prepare the semi-rigid base course mixture according to the design requirements, and lay the semi-rigid base course mixture according to the relevant technical requirements of "Technical Details for Construction of Highway Pavement Base Course" to form the semi-rigid base course of the road.

[0048] Step 2: Prepare the tack coat and seal coat materials according to the design requirements, and apply them sequentially to the upper surface of the semi-rigid base layer according to the designed application timing to form the tack coat and seal coat of the road.

[0049] Step 3: Prepare the asphalt base course mixture according to the design requirements, and lay the asphalt base course mixture on the upper surface of the sealing layer according to the relevant technical requirements of the "Technical Specification for Construction of Highway Asphalt Pavement" to form the asphalt base course of the road;

[0050] Step 4: After the semi-rigid base course, tack coat, seal coat, and asphalt base course are laid in sequence, a semi-rigid base asphalt pavement for shear testing is formed. Shear specimens are prepared on the semi-rigid base asphalt pavement formed by applying the tack coat and seal coat at different application times, and shear tests are conducted separately. At the same time, the shear test results are verified at multiple levels to determine the optimal application time for the integrated application of the tack coat and seal coat.

[0051] In step one, the semi-rigid base mixture is composed of mineral aggregate, cement, and water. The cement content is 5.0 wt% of the mineral aggregate, and the water content is 5.1 wt% of the mineral aggregate. The mineral aggregate is composed of limestone with a particle size of 20-30 mm, limestone with a particle size of 10-20 mm, limestone with a particle size of 5-10 mm, and manufactured sand with a particle size of 0-5 mm. The mass percentages of the limestone with a particle size of 20-30 mm, 10-20 mm, 5-10 mm, and 0-5 mm are 20 wt%, 34 wt%, 16 wt%, and 30 wt%, respectively. The semi-rigid base layer is laid to a thickness of 30 cm.

[0052] In this embodiment, step one involves limestone with a particle size of 20-30mm, limestone with a particle size of 10-20mm, limestone with a particle size of 5-10mm, and manufactured sand with a particle size of 0-5mm. Within each particle size range, there may be raw materials with different particle sizes. For example, limestone with a particle size of 20-30mm is limestone material with a particle size between 20-30mm obtained by passing limestone material through a 30mm sieve and a 20mm sieve in sequence.

[0053] In step two, the tack coat material is PC-2 emulsified asphalt, and the application rate of the tack coat is 1.0 L / m. 2 The seal material is composed of manufactured sand, BC-1 emulsified bitumen, and water. The amount of BC-1 emulsified bitumen added is 13.4 wt% of the manufactured sand, and the amount of water added is 15.0 wt% of the manufactured sand. The manufactured sand is composed of manufactured sand with a particle size of 0-0.6 mm, manufactured sand with a particle size of 0.6-1.18 mm, manufactured sand with a particle size of 1.18-2.36 mm, and manufactured sand with a particle size of 2.36-4.75 mm, wherein the mass percentages of the manufactured sand with a particle size of 0-0.6 mm, 0.6-1.18 mm, 1.18-2.36 mm, and 2.36-4.75 mm are 39 wt%, 20 wt%, 26 wt%, and 15 wt%, respectively. The thickness of the seal layer is 8 mm.

[0054] In this embodiment, step two involves manufactured sand with particle sizes of 0-0.6mm, 0.6-1.18mm, 1.18-2.36mm, and 2.36-4.75mm. Within each particle size range, there may be raw materials with different particle sizes. For example, manufactured sand with a particle size of 2.36-4.75mm is manufactured sand material with a particle size between 2.36-4.75mm obtained by passing the manufactured sand material through a 4.75mm sieve and a 2.36mm sieve in sequence.

[0055] This embodiment designs at least thirty combinations of application timing for the tack coat and seal coat. For each application timing combination, at least three valid shear specimens are prepared. The test data from the three shear specimens are then averaged, and this average value is used as the test result for that application timing combination for analysis and verification. The application timing range for the tack coat is 0-28 days, and the application timing range for the seal coat is 0-28 days, where day 0 is the day the semi-rigid base layer is laid, and a day is calculated as 24 hours.

[0056] In step three, the asphalt lower layer mixture consists of aggregate and asphalt, with the asphalt content being 4.0 wt% of the aggregate. The aggregate comprises limestone with a particle size of 22-30 mm, limestone with a particle size of 16-22 mm, limestone with a particle size of 12-16 mm, limestone with a particle size of 6-12 mm, limestone with a particle size of 3-6 mm, manufactured sand with a particle size of 0-3 mm, mineral powder, and quicklime, wherein the particle size is 22-30 mm. The limestone, limestone with a particle size of 16-22mm, limestone with a particle size of 12-16mm, limestone with a particle size of 6-12mm, limestone with a particle size of 3-6mm, manufactured sand with a particle size of 0-3mm, mineral powder and quicklime account for 15wt%, 15wt%, 19wt%, 20wt%, 6wt%, 22wt%, 2wt% and 1wt% of the mass of the mineral materials, respectively; the thickness of the asphalt underlayer is 4cm.

[0057] In this embodiment, step three involves limestone with a particle size of 22-30mm, limestone with a particle size of 16-22mm, limestone with a particle size of 12-16mm, limestone with a particle size of 6-12mm, limestone with a particle size of 3-6mm, and manufactured sand with a particle size of 0-3mm. Within each particle size range, there may be raw materials with different particle sizes. For example, limestone with a particle size of 22-30mm is limestone material with a particle size between 22-30mm obtained by passing limestone material through a 30mm sieve and a 22mm sieve in sequence.

[0058] In this embodiment, the limestone, manufactured sand, mineral powder, quicklime, and cement used in the preparation of the semi-rigid base course, prime coat, seal coat, and asphalt base course are sourced from Shandong Huitai Mining Co., Ltd., while the asphalt and emulsified asphalt are sourced from Shandong Expressway Materials Group Co., Ltd. The proportions of the raw materials for the semi-rigid base course, prime coat, seal coat, and asphalt base course are important, but there are no special limitations on the mixing process, cement type, asphalt type, mineral powder particle size, quicklime particle size, or other parameters.

[0059] The selected road section in this embodiment is the Linzi-Linyi Expressway. The road surface is laid on site, and shear specimens are made on site. Then, the shear specimens are brought back to the laboratory for shear testing. The shearing equipment used is the equipment described in application number 202211163381.6, entitled "Testing machine and test method for measuring interlayer shear strength of road in indoor and outdoor environments". Alternatively, the equipment described in application number 202310979966.3, entitled "Testing machine and test method for measuring interlayer shear strength of road in indoor and outdoor environments", or existing shearing equipment can be used. Regardless of which shearing equipment is used, as long as the technical solution described in this embodiment is followed, the optimal timing for the integrated application of the tack coat and seal coat can be determined. Figure 2Photos of the on-site application of tack coat and seal coat; Figure 3 The photos are of several shear specimens taken on site. In this embodiment, the total number of shear specimens with different spraying timing combinations is no less than one hundred. Figure 4 This is a photograph of the shearing test process.

[0060] Step four involves conducting shear tests on semi-rigid base asphalt pavement shear specimens with different combinations of application timing for tack coat and seal coat. The method for multi-level verification of the shear test results includes the following steps in sequence:

[0061] Step A: Conduct shear tests on shear specimens with different spraying timing combinations to obtain the relationship curves between interlayer shear force and shear displacement, and convert the relationship curves between interlayer shear force and shear displacement into the relationship curves between interlayer shear stress and shear displacement; Step B: Find the maximum interlayer shear stress on each relationship curve between interlayer shear stress and shear displacement, and then sort each maximum interlayer shear stress by magnitude. The spraying timing combination corresponding to the largest maximum interlayer shear stress is taken as the initial optimal spraying timing for integrated penetration and sealing layers.

[0062] Step C: Perform the first-level verification of the shear test results, that is, use the interlaminar shear modulus model to calculate the interlaminar shear modulus of the shear specimens with different spraying timing combinations, and then sort each interlaminar shear modulus by size.

[0063] Step D: Perform a second-level verification of the shear test results, that is, find the maximum slope of each interlaminar shear stress versus shear displacement curve, take the maximum slope as the maximum stiffness of the shear specimen, and then sort each maximum stiffness by size.

[0064] Step E: Perform third-level verification of the shear test results. That is, on each interlaminar shear stress versus shear displacement curve, draw a vertical line from the point corresponding to the maximum interlaminar shear stress to the horizontal axis, and at the same time draw a diagonal line from the point corresponding to the maximum interlaminar shear stress. This diagonal line is parallel to the secant line corresponding to the maximum slope on the curve. At this time, the diagonal line divides the area enclosed by the curve and the vertical line into left and right parts. Then, sort the area of ​​the left region in each curve by size, and sort the ratio of the area of ​​the left region to the area of ​​the right region in each curve by size.

[0065] Step F: If the shear specimen corresponding to the largest interlaminar shear stress has the largest interlaminar shear modulus, maximum stiffness, left area, and ratio of left area to right area, then the spraying timing combination corresponding to the shear specimen with the largest interlaminar shear stress is taken as the optimal spraying timing for the final integrated permeation and seal coat. Otherwise, for the third-level verification, the ranking of the left area and the ratio of left area to right area needs to be considered comprehensively, and the spraying timing combination corresponding to the shear specimen with the largest comprehensive ranking is taken as the optimal spraying timing for the final integrated permeation and seal coat.

[0066] In step C, the interlaminar shear modulus model is: In the formula,

[0067] E d — Interlaminar shear modulus, in MPa / mm;

[0068] τ max —Maximum inter-story shear stress, in MPa;

[0069] S1—Shear displacement corresponding to 0.2 times the maximum inter-story shear stress, in mm;

[0070] S2 — Shear displacement corresponding to 0.8 times the maximum inter-layer shear stress, in mm.

[0071] In this embodiment, the interlayer shear modulus refers to the shear stress generated at the interface when the upper and lower pavement layers undergo a unit relative displacement. The interlayer shear modulus is used to evaluate the bonding state between layers: a larger interlayer shear modulus value indicates better interlayer bonding performance and a more complete continuity between layers; a smaller interlayer shear modulus value indicates poorer interlayer bonding performance and a greater tendency for slippage between layers.

[0072] In step E, the area of ​​the left region represents the energy required for interlayer failure. The larger the area of ​​the left region, the more difficult the interlayer failure is, and the better the bonding performance of the pass layer and the seal layer. The area of ​​the right region represents the energy lost during the interlayer failure process. The smaller the area of ​​the right region, the less ineffective work is done during the interlayer failure process.

[0073] In this embodiment, the region enclosed by the inclined line passing through the maximum shear stress and the vertical line passing through the maximum shear stress is divided into left and right parts. The interlayer adhesion performance of the shear specimen is further evaluated by the ratio of the area of ​​the left region to the area of ​​the right region. The area of ​​the left region is crucial; the larger the area of ​​the left region, the better the adhesion performance of the tack coat and the seal coat, thus determining the optimal timing for integrated application of the tack coat and the seal coat. In this embodiment, the tack coat and the seal coat are applied separately, according to their respective application times; however, the shear test is conducted integratedly, and the determination of the optimal application time is also integrated. The application times of the tack coat and the seal coat must be mutually constrained to ultimately form the optimal combination of application times.

[0074] In step F, the optimal timing for the integrated application of the tack coat and seal coat is determined to be 0.5-1.5 days between the application of the tack coat and seal coat, with the tack coat applied on days 6-8 and the seal coat applied on days 7-9. In this embodiment, the technical solution involves on-site construction and sample preparation. Due to the influence of the natural environment, the optimal combination of timing for the integrated application of the tack coat and seal coat is given in the form of a time range or time window, which is applicable to most construction sites. Within the aforementioned time window, a more preferred optimal combination of timing for the integrated application of the tack coat and seal coat is that the application time interval between the tack coat and seal coat is 1 day, with the tack coat applied on day 7 (T7) and the seal coat applied on day 8 (F8). That is, the tack coat is applied on the 7th day after the semi-rigid base layer is laid, and the seal coat is applied on the 8th day, with 1 day calculated as 24 hours.

[0075] Figure 5 The graph shows the relationship between interlaminar shear stress and shear displacement for shear specimens at the optimal application timing combination of the tack coat and seal coat (T7F8-1). From the graph, we can determine that the maximum interlaminar shear stress is 0.48615 MPa, corresponding to a shear displacement of 7.1826 mm; 0.2 times the maximum interlaminar shear stress is 0.09723 MPa, corresponding to a shear displacement of 2.1157 mm; and 0.8 times the maximum interlaminar shear stress is 0.38892 MPa, corresponding to a shear displacement of 3.8732 mm. Based on the interlaminar shear modulus model, the interlaminar shear modulus E is calculated. d = 0.16597 MPa / mm.

[0076] Curve fitting was performed on the graph, yielding a maximum slope K = 0.18354. This maximum slope was taken as the maximum stiffness of the shear specimen for this spraying timing combination (T7F8-1). The mathematical expression for the secant line corresponding to this maximum slope is Y = 0.18354X - 0.32491. The secant line corresponding to the maximum stiffness of the shear specimen for this spraying timing combination (T7F8-1) is shown below. Figure 6 As shown.

[0077] Draw a perpendicular line from the point corresponding to the maximum interlaminar shear stress to the horizontal axis, and simultaneously draw an oblique line parallel to the secant from the same point. Alternatively, translate the secant to the point corresponding to the maximum interlaminar shear stress. The mathematical expression for the translated oblique line or secant is Y = 0.18354X - 0.83214, and the intersection of the oblique line and the X-axis is (4.5338, 0). This oblique line divides the area enclosed by the curve and the perpendicular line into left and right parts. The area division of the left and right regions in the curve of interlaminar shear stress versus shear displacement of the shear specimen with this spraying timing combination (T7F8-1) is as follows. Figure 7 As shown.

[0078] The method for determining the optimal application timing of the integrated road tack coat and seal coat in this embodiment can accurately determine the optimal application timing combination of the tack coat and seal coat, improve construction efficiency, and reduce maintenance costs. The application timing combination of the tack coat and seal coat determined by the method in this embodiment will not cause cracking of the semi-rigid base layer, and the interlayer adhesion between the semi-rigid base layer and the asphalt pavement is strong enough, thereby improving the service life of the road. At the same time, it also lays the foundation for the revision of the specifications.

[0079] Furthermore, the optimal application window for the integrated tack coat and seal coat, as determined in this embodiment, is as follows: the tack coat should be applied at 6-8 days, the seal coat at 7-9 days, and the application interval between the tack coat and seal coat should be 0.5-1.5 days. As long as the application timing falls within these windows, it is acceptable. The tack coat application rate is 0.8-1.2 L / m². 2 It is suitable for sealing layer with a thickness of 6-10mm, semi-rigid base layer with a thickness of 20-40cm, and asphalt subbase layer with a thickness of 3-5cm.

[0080] Special Note: The technical solution of this invention involves numerous parameters, and the synergistic effects between these parameters must be comprehensively considered to achieve the beneficial effects and significant progress of this invention. Furthermore, the value ranges of each parameter in the technical solution were obtained through extensive experimentation. For each parameter and the combinations thereof, the inventors have recorded a large amount of experimental data; however, due to space limitations, the specific experimental data is not disclosed here.

[0081] Those skilled in the art will readily understand that the method for determining the optimal application time of the integrated road permeable layer and sealant of the present invention includes any combination of the inventive content and specific embodiments described in the above specification and the various parts shown in the accompanying drawings. Due to space limitations and for the sake of brevity, not all of these combinations have been described in detail. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for determining the optimal application time of an integrated road tack coat and seal coat, characterized in that, The determination method includes the following steps in sequence: Step 1: Prepare the semi-rigid base course mixture according to the design requirements, and lay the semi-rigid base course mixture according to the relevant technical requirements of "Technical Details for Construction of Highway Pavement Base Course" to form the semi-rigid base course of the road. Step 2: Prepare the tack coat and seal coat materials according to the design requirements, and apply them sequentially to the upper surface of the semi-rigid base layer according to the designed application timing to form the tack coat and seal coat of the road. Step 3: Prepare the asphalt base course mixture according to the design requirements, and lay the asphalt base course mixture on the upper surface of the sealing layer according to the relevant technical requirements of the "Technical Specification for Construction of Highway Asphalt Pavement" to form the asphalt base course of the road; Step 4: After the semi-rigid base course, tack coat, seal coat, and asphalt base course are laid in sequence, a semi-rigid base asphalt pavement for shear testing is formed. Shear specimens are prepared on the semi-rigid base asphalt pavement formed by applying the tack coat and seal coat at different application times, and shear tests are conducted separately. At the same time, the shear test results are verified at multiple levels to determine the optimal application time for the integrated application of the tack coat and seal coat. Step four involves multi-level verification of the shear test results, which includes the following steps in chronological order: Step A: Conduct shear tests on shear specimens with different spraying timing combinations to obtain the relationship curves between interlayer shear force and shear displacement, and convert the relationship curves between interlayer shear force and shear displacement into the relationship curves between interlayer shear stress and shear displacement; Step B: Find the maximum interlayer shear stress on each relationship curve between interlayer shear stress and shear displacement, and then sort each maximum interlayer shear stress by magnitude. The spraying timing combination corresponding to the largest maximum interlayer shear stress is taken as the initial optimal spraying timing for integrated penetration and sealing layers. Step C: Perform the first-level verification of the shear test results, that is, use the interlaminar shear modulus model to calculate the interlaminar shear modulus of the shear specimens with different spraying timing combinations, and then sort each interlaminar shear modulus by size. Step D: Perform a second-level verification of the shear test results, that is, find the maximum slope of each interlaminar shear stress versus shear displacement curve, take the maximum slope as the maximum stiffness of the shear specimen, and then sort each maximum stiffness by size. Step E: Perform third-level verification of the shear test results. That is, on each interlaminar shear stress versus shear displacement curve, draw a vertical line from the point corresponding to the maximum interlaminar shear stress to the horizontal axis, and at the same time draw a diagonal line from the point corresponding to the maximum interlaminar shear stress. This diagonal line is parallel to the secant line corresponding to the maximum slope on the curve. At this time, the diagonal line divides the area enclosed by the curve and the vertical line into left and right parts. Then, sort the area of ​​the left region in each curve by size, and sort the ratio of the area of ​​the left region to the area of ​​the right region in each curve by size. Step F: If the shear specimen corresponding to the largest interlaminar shear stress has the largest interlaminar shear modulus, maximum stiffness, left area, and ratio of left area to right area, then the spraying timing combination corresponding to the shear specimen with the largest interlaminar shear stress is taken as the best spraying timing for the final integrated tack coat and seal coat. Otherwise, for the third-level verification, it is necessary to comprehensively consider the ranking of the left area and the ratio of left area to right area, and take the spraying timing combination corresponding to the shear specimen with the largest comprehensive ranking as the best spraying timing for the final integrated tack coat and seal coat. In step C, the interlaminar shear modulus model is: In the formula, E d — Interlaminar shear modulus, in MPa / mm; τ max —Maximum inter-story shear stress, in MPa; S1—Shear displacement corresponding to 0.2 times the maximum inter-story shear stress, in mm; S2 — Shear displacement corresponding to 0.8 times the maximum inter-layer shear stress, in mm.

2. The method for determining the optimal application time of the integrated road surface coat and seal coat according to claim 1, characterized in that, In step one, the semi-rigid base mixture is composed of mineral aggregate, cement, and water. The cement content is 5.0 wt% of the mineral aggregate, and the water content is 5.1 wt% of the mineral aggregate. The mineral aggregate is composed of limestone with a particle size of 20-30 mm, limestone with a particle size of 10-20 mm, limestone with a particle size of 5-10 mm, and manufactured sand with a particle size of 0-5 mm. The mass percentages of the limestone with a particle size of 20-30 mm, 10-20 mm, 5-10 mm, and 0-5 mm are 20 wt%, 34 wt%, 16 wt%, and 30 wt%, respectively. The semi-rigid base layer is laid to a thickness of 20-40 cm.

3. The method for determining the optimal application time of the integrated road priming and sealing coat according to claim 2, characterized in that, In step two, the tack coat material is PC-2 emulsified asphalt, and the application rate of the tack coat is 0.8-1.2 L / m. 2 .

4. The method for determining the optimal application time of the integrated road priming and sealing coat according to claim 3, characterized in that, In step two, the seal material is composed of manufactured sand, BC-1 emulsified asphalt, and water. The amount of BC-1 emulsified asphalt added is 13.4 wt% of the manufactured sand, and the amount of water added is 15.0 wt% of the manufactured sand. The manufactured sand is composed of manufactured sand with a particle size of 0-0.6 mm, manufactured sand with a particle size of 0.6-1.18 mm, manufactured sand with a particle size of 1.18-2.36 mm, and manufactured sand with a particle size of 2.36-4.75 mm, wherein the mass percentages of the manufactured sand with a particle size of 0-0.6 mm, 0.6-1.18 mm, 1.18-2.36 mm, and 2.36-4.75 mm are 39 wt%, 20 wt%, 26 wt%, and 15 wt%, respectively. The thickness of the seal layer is 6-10 mm.

5. The method for determining the optimal application time of the integrated road priming and sealing coat according to claim 4, characterized in that, In step two, at least thirty combinations of application timing for the tack coat and the seal coat are designed, wherein the application timing range for the tack coat is 0-28 days, and the application timing range for the seal coat is 0-28 days, where day 0 is the day the semi-rigid base layer is laid, and a day is calculated as 24 hours.

6. The method for determining the optimal application time of the integrated road priming and sealing coat according to claim 5, characterized in that, In step three, the asphalt lower layer mixture consists of aggregate and asphalt, with the asphalt content being 4.0 wt% of the aggregate. The aggregate comprises limestone with a particle size of 22-30 mm, limestone with a particle size of 16-22 mm, limestone with a particle size of 12-16 mm, limestone with a particle size of 6-12 mm, limestone with a particle size of 3-6 mm, manufactured sand with a particle size of 0-3 mm, mineral powder, and quicklime, wherein the aggregate with a particle size of 22-30 mm... The mass percentages of the following materials are respectively: limestone, limestone with a particle size of 16-22mm, limestone with a particle size of 12-16mm, limestone with a particle size of 6-12mm, limestone with a particle size of 3-6mm, manufactured sand with a particle size of 0-3mm, mineral powder, and quicklime, which account for 15wt%, 15wt%, 19wt%, 20wt%, 6wt%, 22wt%, 2wt%, and 1wt% of the aggregate; the thickness of the asphalt sublayer is 3-5cm.

7. The method for determining the optimal application time of the integrated road priming and sealing coat according to claim 6, characterized in that, In step E, the area of ​​the left region represents the energy required for interlayer failure. The larger the area of ​​the left region, the more difficult the interlayer failure is, and the better the bonding performance of the pass layer and the seal layer. The area of ​​the right region represents the energy lost during the interlayer failure process. The smaller the area of ​​the right region, the less ineffective work is done during the interlayer failure process.

8. The method for determining the optimal application time of the integrated road priming and sealing coat according to claim 7, characterized in that, In step F, the optimal timing for the integrated application of the tack coat and seal coat is determined to be 0.5-1.5 days between the application of the tack coat and the seal coat, with the tack coat being applied at 6-8 days and the seal coat at 7-9 days.

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