A semi-flexible composite pavement material based on a modulus transition layer and its application

Abstract

The present invention relates to the technical field of road engineering, and proposes a semi-flexible composite pavement material based on a modulus transition layer and its application. The semi-flexible composite pavement material comprises a large-void matrix asphalt mixture and a cement-based grouting mixture; the large-void matrix asphalt mixture comprises aggregate, mineral powder, succinimide-modified rubber powder and SBS modified asphalt; the cement-based grouting mixture comprises cement-based grouting material and water. The present invention introduces succinimide-modified rubber powder as a modulus transition layer material between the asphalt-cement grouting material interface in the anti-cracking semi-flexible composite pavement material, thereby reducing the deformation difference between the rigid cement grouting material and the flexible asphalt mixture of the semi-flexible composite pavement material under load, thereby solving the problem of cracking of the semi-flexible composite pavement.

Description

Technical Field

[0001] The invention relates to the technical field of road engineering, and in particular to a semi-flexible composite pavement material based on a modulus transition layer and application thereof. Background Art

[0002] Traditional road surfaces include asphalt pavement and cement pavement, each with its own advantages and disadvantages. Asphalt pavement is widely used due to its high driving comfort, easy maintenance and good anti-skid performance, but asphalt is a viscoelastic material, which is prone to rutting under high temperature and heavy load traffic conditions, and cracking under low temperature conditions; cement pavement has a large bearing capacity and good durability, but it has the disadvantages of long construction and curing time and joints that affect driving comfort. Once a disease occurs, it is difficult to maintain and repair.

[0003] In order to overcome the shortcomings of cement pavement and asphalt pavement, semi-flexible pavement materials came into being. They have excellent rutting resistance, wear resistance, oil resistance and other properties, and are widely used in the construction of special sections such as toll plazas, airport runways, municipal road intersections, BRT lanes, heavy-duty traffic industrial park roads, and port terminals. However, cracking has become a key disease that needs to be solved in the promotion of semi-flexible pavements. As a composite material with coexistence of rigidity and flexibility, due to the large difference in modulus between the asphalt matrix and cement slurry, microcracks are easily generated at the interface between the large-pore asphalt matrix and cement grouting material, and gradually expand into macro cracks. In order to improve the crack resistance of semi-flexible pavements, current research mainly focuses on improving the overall strength, such as using high-modulus asphalt binder, high-strength cement grouting material or increasing the amount of grouting material. However, these methods focus on improving the stiffness of the pavement to reduce load damage, and fail to effectively solve the deformation coordination problem between cement grouting material and asphalt matrix, making it difficult to fundamentally inhibit interface damage and cracks. Summary of the invention

[0004] In view of this, the present invention proposes a semi-flexible composite pavement material based on a modulus transition layer and its application. The main purpose is to overcome the shortcomings of the existing semi-flexible composite pavement technology, solve or alleviate the cracking problem of the semi-flexible pavement material due to the large difference in modulus between asphalt and cement grouting materials and the uncoordinated deformation under load, thereby improving the durability of the semi-flexible composite pavement and promoting the large-scale application of semi-flexible pavements.

[0005] The technical solution of the present invention is implemented as follows: On the one hand, the present invention provides a semi-flexible composite pavement material based on a modulus transition layer, comprising a large-void matrix asphalt mixture, an organic phosphate coupling agent and a cement-based grouting mixture;

[0006] The macrovoid matrix asphalt mixture comprises aggregate, mineral powder, succinimide modified rubber powder and SBS modified asphalt;

[0007] The cement-based grouting mixture comprises a cement-based grouting material and water.

[0008] On the basis of the above technical solution, preferably, the pavement material includes 70-85 parts of large-void matrix asphalt mixture and 15-30 parts of cement-based grouting mixture in parts by weight;

[0009] The mass ratio of the aggregate, mineral powder, succinimide modified rubber powder and SBS modified asphalt is 64-79.4:1-3:0.6-1:2-4, and the water-cement ratio of the cement-based grouting mixture is 0.3-0.32.

[0010] On the basis of the above technical solution, preferably, the pavement material further includes an organic phosphate coupling agent, and 0.1-0.3 g of the organic phosphate coupling agent is sprayed per cubic meter of large-void matrix asphalt mixture.

[0011] On the basis of the above technical solution, preferably, the preparation method of the succinimide modified rubber powder comprises the following steps:

[0012] S1, dissolving succinic acid and ammonia water in an ethanol solvent, and heating to cause ammonia and succinic acid to undergo a cyclization reaction to generate succinimide;

[0013] S2, transferring the rubber powder and succinimide into a mixer, and reacting for 0.5-1h to obtain succinimide-modified rubber powder.

[0014] On the basis of the above technical solution, preferably, in step S1, the mass ratio of succinic acid, aqueous ammonia (concentration of 25%) and ethanol is 50-60:30-35:20-30, and the temperature of the cyclization reaction is 150°C-200°C.

[0015] On the basis of the above technical solution, preferably, in step S2, the mass ratio of the rubber powder to succinimide is 1:0.8~1, the mixing machine is set to a stirring speed of 50~100 rpm, and the temperature is 150°C~180°C.

[0016] On the basis of the above technical solution, preferably, the organic phosphate coupling agent is one or more of triphenyl phosphate, tri(n-butyl) phosphate and tri(ethyl) phosphate.

[0017] On the basis of the above technical scheme, preferably, the aggregate is basalt aggregate with a particle size of ≤16mm; the mineral powder is limestone mineral powder with a particle size of ≤100μm; the rubber powder is powdered waste tires with a mesh size of 40-60 mesh; the cement-based grouting material is JGM-301 type semi-flexible pavement special cement-based grouting material, and the SBS modified asphalt is PG76-22 type modified asphalt.

[0018] On the other hand, the present invention provides an application of a semi-flexible composite pavement material based on a modulus transition layer in improving the crack resistance of a pavement.

[0019] On the basis of the above technical solution, preferably, the pavement construction method comprises the following steps:

[0020] S1, on the basis of SBS modified asphalt, succinimide modified rubber powder is added in stages at 170-175℃ to react, to prepare rubber modified asphalt, then aggregate and mineral powder are added to mix, compacted and molded to obtain large-void matrix asphalt mixture (wet method adding rubber powder); or the aggregate is heated to 170-175℃, then mineral powder, succinimide modified rubber powder and SBS modified asphalt are added to mix, compacted and molded to obtain large-void matrix asphalt mixture (dry method adding rubber powder);

[0021] S2, mixing the cement-based grouting material with water and stirring evenly to obtain a cement-based grouting mixture;

[0022] S3, after the test piece of step S1 is cooled to 50-60°C, an organic phosphate coupling agent is sprayed, and then a cement-based grouting mixture is poured in and cured for 1-3 hours to obtain a semi-flexible composite material test piece with a modulus transition layer.

[0023] On the basis of the above technical solution, preferably, in step S1, the method of adding succinimide-modified rubber powder in stages is:

[0024] The first stage: 0-15min, add 20%~30% mass fraction of succinimide modified rubber powder, stirring speed is 4000~5000rpm;

[0025] The second stage: 15-30min, add 40%~50% mass fraction of succinimide modified rubber powder, stirring speed is 4000~5000rpm;

[0026] The third stage: 30-45 minutes, add the remaining succinimide modified rubber powder, and the stirring speed is 4000~5000rpm.

[0027] The semi-flexible composite pavement material based on the modulus transition layer and its application of the present invention have the following beneficial effects compared with the prior art:

[0028] (1) Rubber powder is a commonly used elastic material in road engineering. As a common asphalt modifier, the swelling effect of rubber powder can significantly improve the performance of asphalt binder. On the one hand, the rubber powder is desulfurized and degraded, and some polymers are dissolved into the asphalt component to modify the matrix asphalt; on the other hand, the volume of the rubber particles expands after absorbing the light components of the asphalt, the free space between the particles is reduced, and the internal viscosity of the system is greatly increased, forming a stiffening effect. Succinimide provides amino groups (-NH) to enhance the compatibility of the rubber-asphalt interface. The swollen rubber powder has a particle effect of "tough inside and soft outside", which can be used as the rigidity transition layer of semi-flexible pavement materials, forming a deformation coordination interface of "flexible asphalt-elastic rubber powder-rigid cement", and improving the crack resistance of semi-flexible pavement materials. The present invention introduces rubber powder as a modulus transition layer material between the asphalt-cement grouting material interface in the crack-resistant semi-flexible composite pavement material, thereby reducing the deformation difference between the rigid cement grouting material and the flexible asphalt mixture of the semi-flexible composite pavement material under load, thereby solving the cracking problem of the semi-flexible composite pavement.

[0029] (2) The silicate component (CSH gel) in cement contains silanol groups (-SiOH). The oxygen atoms in the phosphate groups of the organic phosphate coupling agent react with the silanol groups (-SiOH) on the cement surface to form Si-OP bonds, which improves the adhesion between cement and organic polymers and thus improves the overall performance of pavement materials.

[0030] In addition, it should be pointed out that it is precisely because of the synergistic effect and mutual coordination of the above-mentioned mechanisms that the semi-flexible composite pavement based on the modulus transition layer provided by the present invention significantly improves the material's anti-cracking performance, balances the deformation capacity between cement-based grouting materials and asphalt, and gives it excellent durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 It is the action mechanism diagram between organic phosphate coupling agent and cement grouting material asphalt, R is the organic functional group in the asphalt material;

[0033] Figure 2 This is a rendering of the "tough inside and soft outside" characteristics of the swelling rubber powder of the semi-flexible composite pavement modulus transition layer material. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The cement-based grouting material is JGM-301 semi-flexible pavement special cement-based grouting material purchased from Jiangsu Subote New Materials Co., Ltd. The SBS modified asphalt is PG76-22 modified asphalt purchased from Huayuntongda Road Technology Co., Ltd.

[0036] Example 1

[0037] This embodiment adopts a wet method of adding rubber powder step by step as the semi-flexible composite pavement modulus transition layer material, and the material composition is shown in Table 1.

[0038]

[0039] The preparation method of the semi-flexible composite pavement modulus transition layer material is as follows:

[0040] S1, Preparation of succinimide modified rubber powder:

[0041] 550g of succinic acid and 330g of ammonia water (25wt%) were dissolved in 250g of ethanol solvent, and heated to 180°C to allow ammonia and succinic acid to undergo a cyclization reaction to generate succinimide; then 400g of rubber powder and 350g of succinimide were transferred into a mixer, and mixed at 80rpm and 160°C for 1h to obtain succinimide-modified rubber powder.

[0042] S2, SBS / rubber powder composite modified asphalt:

[0043] On the basis of SBS modified asphalt, succinimide modified rubber powder was added in stages at 175°C for reaction. In the first stage (0-15min), 25% by mass of succinimide modified rubber powder was added, the temperature was 175°C, and the stirring speed was 4500rpm; in the second stage (15-30min), 45% by mass of succinimide modified rubber powder was added, the temperature was 175°C, and the stirring speed was 4500rpm; in the third stage (30-45min), the remaining succinimide modified rubber powder was added, the temperature was 175°C, and the stirring speed was 5000rpm, and SBS / rubber powder composite modified asphalt was obtained.

[0044] S3, first heat the aggregate and mineral powder to 175℃ to ensure that the materials are dry and have good heating conditions, then mix the aggregate, mineral powder, SBS / rubber powder composite modified asphalt (175℃) evenly, and compact them to obtain a large-void matrix asphalt mixture skeleton specimen with a modulus transition layer.

[0045] S4, after the specimen is cooled to 55°C, the mixed cement-based grouting mixture (water-cement ratio 0.3) is poured into it to evenly fill the pores of the asphalt matrix. The mixture is cured for 2 hours to finally obtain a semi-flexible composite material specimen with a modulus transition layer.

[0046] Example 2

[0047] This embodiment adopts a wet method of adding rubber powder step by step as a semi-flexible composite pavement modulus transition layer material. Compared with Example 1, Example 2 adds triphenyl phosphate coupling agent, and the material composition is shown in Table 2.

[0048]

[0049] The preparation method of the semi-flexible composite pavement modulus transition layer material is as follows:

[0050] S1, preparation of succinimide modified rubber powder: same as Example 1.

[0051] S2, SBS / rubber powder composite modified asphalt: same as Example 1.

[0052] S3, same as Example 1.

[0053] S4, after the specimen is cooled to 55°C, spray triphenyl phosphate coupling agent, and then pour in the mixed cement-based grouting mixture (water-cement ratio 0.3) to evenly fill it into the pores of the asphalt matrix. Curing and curing for 2 hours, finally a semi-flexible composite material specimen with a modulus transition layer is obtained.

[0054] Example 3

[0055] This embodiment adopts the dry method of adding rubber powder step by step as the semi-flexible composite pavement modulus transition layer material, and the material composition is the same as that of Example 2.

[0056] The preparation method of the semi-flexible composite pavement modulus transition layer material is as follows:

[0057] S1, preparation of succinimide modified rubber powder: same as Example 1.

[0058] S2, add hot aggregate (175℃) and mineral powder, succinimide modified rubber powder, and SBS modified asphalt (175℃) into the mixing equipment, mix them evenly and compact them to obtain a large-void matrix asphalt mixture skeleton specimen with a modulus transition layer.

[0059] S3, after the specimen is cooled to 55°C, spray triphenyl phosphate coupling agent, and then pour in the mixed cement-based grouting mixture (water-cement ratio 0.3) to evenly fill it into the pores of the asphalt matrix. Curing and curing for 2 hours, finally a semi-flexible composite material specimen with a modulus transition layer is obtained.

[0060] Example 4

[0061] This embodiment adopts a wet method of adding rubber powder step by step as the semi-flexible composite pavement modulus transition layer material, and the material composition is shown in Table 3.

[0062]

[0063] The preparation method of the semi-flexible composite pavement modulus transition layer material is as follows:

[0064] S1, Preparation of succinimide modified rubber powder:

[0065] 500g of succinic acid and 300g of ammonia water (25wt%) were dissolved in 200g of ethanol solvent, and heated to 150°C to allow ammonia and succinic acid to undergo a cyclization reaction to generate succinimide; then 400g of rubber powder and 320g of succinimide were transferred into a mixer, and mixed at 50rpm and 150°C for 0.5h to obtain succinimide-modified rubber powder.

[0066] S2, SBS / rubber powder composite modified asphalt:

[0067] On the basis of SBS modified asphalt, succinimide modified rubber powder is added in stages at 170°C for reaction. In the first stage (0-15min), 20% mass fraction of succinimide modified rubber powder is added, the temperature is 170°C, and the stirring speed is 4000rpm; in the second stage (15-30min), 40% mass fraction of succinimide modified rubber powder is added, the temperature is 170-175°C, and the stirring speed is 4000rpm; in the third stage (30-45min), the remaining succinimide modified rubber powder is added, the temperature is 170°C, and the stirring speed is 4000rpm, and the SBS / rubber powder composite modified asphalt can be obtained.

[0068] S3, first heat the aggregate and mineral powder to 170℃ to ensure that the materials are dry and have good heating conditions, then mix the aggregate, mineral powder and SBS / rubber powder composite modified asphalt evenly, and compact them to obtain a large-void matrix asphalt mixture skeleton specimen with a modulus transition layer.

[0069] S4, after the specimen is cooled to 50°C, spray triphenyl phosphate coupling agent, and then pour in the mixed cement-based grouting mixture to evenly fill the pores of the asphalt matrix. Curing and curing for 1 hour, finally a semi-flexible composite material specimen with a modulus transition layer is obtained.

[0070] Example 5

[0071] This embodiment adopts the wet method of adding rubber powder step by step as the semi-flexible composite pavement modulus transition layer material, and the material composition is shown in Table 4.

[0072]

[0073] The preparation method of the semi-flexible composite pavement modulus transition layer material is as follows:

[0074] S1, preparation of succinimide modified rubber powder:

[0075] 600 g of succinic acid and 350 g of ammonia water (25 wt%) were dissolved in 300 g of ethanol solvent and heated to 200 °C to allow ammonia and succinic acid to undergo a cyclization reaction to generate succinimide; then 400 g of rubber powder and 400 g of succinimide were transferred into a mixer and mixed at 100 rpm and 180 °C for 1 h to obtain succinimide-modified rubber powder.

[0076] S2, SBS / rubber powder composite modified asphalt:

[0077] On the basis of SBS modified asphalt, succinimide modified rubber powder was added in stages at 173°C for reaction. In the first stage (0-15min), 30% by mass of succinimide modified rubber powder was added, the temperature was 173°C, and the stirring speed was 5000rpm; in the second stage (15-30min), 50% by mass of succinimide modified rubber powder was added, the temperature was 173°C, and the stirring speed was 5000rpm; in the third stage (30-45min), the remaining succinimide modified rubber powder was added, the temperature was 173°C, and the stirring speed was 5000rpm, and the SBS / rubber powder composite modified asphalt was obtained.

[0078] S3, first heat the aggregate and mineral powder to 180℃ to ensure that the materials are dry and have good heating conditions, then mix the aggregate, mineral powder, SBS / rubber powder composite modified asphalt (180℃) evenly, and compact them to obtain a large-void matrix asphalt mixture skeleton specimen with a modulus transition layer.

[0079] S4, after the specimen is cooled to 60°C, spray triphenyl phosphate coupling agent, and then pour in the mixed cement-based grouting mixture to evenly fill the pores of the asphalt matrix. Curing and curing for 3 hours, finally a semi-flexible composite material specimen with a modulus transition layer is obtained.

[0080] Comparative Example 1

[0081] Compared with Example 1, Comparative Example 1 does not add succinimide modified rubber powder, the SBS modified asphalt is increased by 0.68 kg, and the rest of the contents are the same as Example 1.

[0082] The preparation method of the semi-flexible composite pavement modulus transition layer material of Comparative Example 1 is:

[0083] S1, first heat the aggregate and mineral powder to 175℃ to ensure that the materials are dry and have good heating conditions, then mix the aggregate, mineral powder and SBS modified asphalt (175℃) evenly, and compact them to obtain a large-void matrix asphalt mixture skeleton specimen with a modulus transition layer.

[0084] S2, after the specimen is cooled to 55°C, spray triphenyl phosphate coupling agent, and then pour in the mixed cement-based grouting mixture (water-cement ratio 0.3) to evenly fill it into the pores of the asphalt matrix. Curing and curing for 2 hours, finally a semi-flexible composite material specimen with a modulus transition layer is obtained.

[0085] Comparative Example 2

[0086] Compared with Example 1, in Comparative Example 2, the rubber powder was not modified, and 0.68 kg of rubber powder was directly added, and the remaining materials and amounts were the same as in Example 1.

[0087] The preparation method of the semi-flexible composite pavement modulus transition layer material of Comparative Example 2 is:

[0088] S1, heat the aggregate and mineral powder to 175℃, ensure that the materials are dry and have good heating conditions, and add rubber powder: on the basis of SBS modified asphalt, in the first stage (0-15min), add 25% mass fraction of rubber powder, the temperature is 175℃, and the stirring speed is 4500rpm; in the second stage (15-30min), add 45% mass fraction of rubber powder, the temperature is 175℃, and the stirring speed is 4500rpm; in the third stage (30-45min), add the remaining rubber powder, the temperature is 175℃, and the stirring speed is 5000rpm, and the SBS / rubber powder composite modified asphalt can be obtained.

[0089] S2, first heat the aggregate and mineral powder to 175℃ to ensure that the materials are dry and have good heating conditions, then mix the aggregate, mineral powder, SBS / rubber powder composite modified asphalt (175℃) evenly, and compact them to obtain a large-void matrix asphalt mixture skeleton specimen with a modulus transition layer.

[0090] S3, after the specimen is cooled to 55°C, spray triphenyl phosphate coupling agent, and then pour in the mixed cement-based grouting mixture (water-cement ratio 0.3) to evenly fill it into the pores of the asphalt matrix. Curing and curing for 2 hours, finally a semi-flexible composite material specimen with a modulus transition layer is obtained.

[0091] Comparative Example 3

[0092] Compared with Example 1, Comparative Example 3, the succinimide modified rubber powder was added at one time, and the materials and dosage were the same as those in Example 1.

[0093] The preparation method of the semi-flexible composite pavement modulus transition layer material of Comparative Example 3 is:

[0094] S1, heat the aggregate and mineral powder to 175℃, ensure that the materials are dry and have good heating conditions, and directly add rubber powder: on the basis of SBS modified asphalt, directly add rubber powder at one time, at a temperature of 175℃ and a stirring speed of 5000rpm, to obtain SBS / rubber powder composite modified asphalt.

[0095] S2, first heat the aggregate and mineral powder to 175℃ to ensure that the materials are dry and have good heating conditions, then mix the aggregate, mineral powder, SBS / rubber powder composite modified asphalt (175℃) evenly, and compact them to obtain a large-void matrix asphalt mixture skeleton specimen with a modulus transition layer.

[0096] S3, after the specimen is cooled to 55°C, spray triphenyl phosphate coupling agent, and then pour in the mixed cement-based grouting mixture (water-cement ratio 0.3) to evenly fill it into the pores of the asphalt matrix. Curing and curing for 2 hours, finally a semi-flexible composite material specimen with a modulus transition layer is obtained.

[0097] Comparative Example 4

[0098] Compared with Example 1, the amount of succinimide modified rubber powder in Comparative Example 4 exceeds the specified range, specifically 1.5 kg, and the remaining materials and amounts are the same as in Example 1.

[0099] Comparative Example 5

[0100] Compared with Example 2, in Comparative Example 5, the amount of interface enhancer used exceeds the specified range, specifically 0.5 g of organic phosphate coupling agent per cubic meter of large-void matrix asphalt mixture, and the remaining components and preparation method are the same as in Example 2.

[0101] Comparative Example 6

[0102] In Comparative Example 6, compared with Example 2, a silane coupling agent is selected as the interface enhancer, and the amount used is the same as that of Example 2. The other materials and amounts used are also the same as those of Example 2.

[0103] The preparation method of the semi-flexible composite pavement modulus transition layer material of Comparative Example 6 is:

[0104] S1, preparation of succinimide modified rubber powder: same as Example 2.

[0105] S2, SBS / rubber powder composite modified asphalt: same as Example 2.

[0106] S3, same as Example 2.

[0107] S4, after the specimen is cooled to 55°C, spray the silane coupling agent (KH560 silane coupling agent), and then pour the mixed cement-based grouting mixture (water-cement ratio 0.3) into it to evenly fill the pores of the asphalt matrix. Curing and curing for 2 hours, finally a semi-flexible composite material specimen with a modulus transition layer is obtained.

[0108] Comparative Example 7

[0109] Comparative Example 7 Compared with Example 2, succinimide modified rubber powder is added to the cement-based grouting mixture, and its materials and dosage are the same as those in Example 2.

[0110] The preparation method of the semi-flexible composite pavement modulus transition layer material of Comparative Example 7 is:

[0111] S1, preparation of succinimide modified rubber powder: same as Example 2.

[0112] S2, rubber powder modified cement-based grouting mixture:

[0113] The succinimide modified rubber powder was added step by step to the mixed cement-based grouting mixture (water-cement ratio 0.3). In the first stage (0-15min), 25% mass fraction of succinimide modified rubber powder was added at a stirring speed of 400rpm; in the second stage (15-30min), 45% mass fraction of succinimide modified rubber powder was added at a stirring speed of 400rpm; in the third stage (30-45min), the remaining succinimide modified rubber powder was added at a stirring speed of 500rpm to obtain a rubber powder-modified cement-based grouting mixture.

[0114] S3, first heat the aggregate and mineral powder to 175℃ to ensure that the materials are dry and have good heating conditions, then mix the aggregate, mineral powder and SBS modified asphalt (175℃), compact and shape them to obtain a large-void matrix asphalt mixture skeleton specimen.

[0115] S4, after the specimen is cooled to 550°C, spray triphenyl phosphate coupling agent, and then pour in the rubber powder modified cement-based grouting mixture to evenly fill it into the pores of the asphalt matrix, solidify and cure for 2 hours, and finally obtain a semi-flexible composite material specimen.

[0116] Performance Testing:

[0117] The performance test of the mixed cement-based grouting material (water-cement ratio 0.3) used in the present invention is carried out, and the test results are shown in the following table:

[0118]

[0119] The semi-flexible composite material specimens of the embodiment and the comparative example were subjected to performance tests, and the test methods were as follows:

[0120] Rutting is an important indicator for evaluating the high-temperature stability of asphalt mixtures. It is reflected by the rutting depth value, and the test method refers to ASTM D6372 specification.

[0121] The low temperature splitting test is used to determine the crack resistance of semi-flexible pavement materials in low temperature environments, which is reflected by the low temperature splitting strength. The test method refers to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), the test temperature is -10 ℃, and the loading rate is 10 mm / min.

[0122] The four-point bending test is mainly used to determine the fatigue life of semi-flexible pavement materials under constant strain or constant stress conditions to evaluate the material's fatigue resistance. It is reflected by fatigue life (number of times). The test method refers to ASTM D7460 specification.

[0123] The indirect tensile test is used to evaluate the water damage resistance of semi-flexible pavement materials. It is characterized by the ITSR value of the tensile strength ratio before and after immersion. The test method refers to the AASHTO T 283 specification.

[0124] The test results are shown in the following table:

[0125]

[0126] Table 6 shows three mixing methods, namely wet method (Examples 1, 2, 4 and 5), dry method (Example 3), and adding cement-based grouting material (Comparative Example 6). In terms of high temperature rutting resistance, the rutting depths of Examples 1-4 are all lower than those of Comparative Example 7, among which the rutting depth of the wet method is shallower. In terms of fatigue performance, the fatigue life of Examples 2 and 3 is higher than that of Comparative Example 7 at any strain level, but Comparative Example 7 has better water damage resistance.

[0127] Compared with Example 2, in Example 1, since no interface enhancer was sprayed, the interface connection between the asphalt and the grouting material was weak, and the interface layer was prone to peeling and damage during low-temperature cracking. Due to the insufficient bonding force of the interface, the synergy between the internal and external materials at high temperatures is insufficient, and the overall rutting resistance is reduced. Interface defects also lead to aggravated delamination under fatigue loads, and cracks are more likely to initiate and expand at the interface, significantly reducing the service life. At the same time, it is also reversely proved that spraying interface enhancers can increase the rutting resistance, strength and fatigue resistance of the pavement.

[0128] The semi-flexible composite pavement modulus transition layer material swelling rubber powder in Examples 2-3 has a "tough inside and soft outside" characteristic effect diagram as shown in the figure. Figure 2 shown.

[0129] Through analysis, it can be seen that the low-temperature crack resistance, high-temperature rutting resistance and fatigue life of the semi-flexible composite pavement modulus transition layer material mixed with rubber powder using the wet process are better than those of the dry process.

[0130]

[0131] By analyzing the test results of the embodiments and comparative examples, it can be seen that in terms of low-temperature crack resistance, the modulus transition layer of the semi-flexible composite pavement material designed based on the "tough inside and soft outside" characteristics of the rubber powder proposed in the present invention can significantly improve the -10°C low-temperature splitting strength of the semi-flexible composite pavement material, thereby reducing the risk of cracking.

[0132] In Table 7, Comparative Example 1 does not add succinimide modified rubber powder, the asphalt matrix lacks sufficient flexibility and toughness, and cannot absorb thermal stress concentration at low temperatures, resulting in easy brittle cracking; the lack of modified rubber powder causes the original asphalt to have greater fluidity at high temperatures and insufficient ability to resist rutting; the asphalt matrix without modified rubber powder is susceptible to cracks under fatigue loads and rapidly expands. In Comparative Example 2, the rubber powder is not modified, and the rubber powder is directly added, resulting in poor compatibility between the rubber powder and the asphalt matrix, unable to form an effective reinforcement network with the asphalt, and insufficient overall toughness; in addition, the unmodified rubber powder has weak uniform dispersibility, and the reinforcement effect at high temperatures is not significant, resulting in weak resistance to rheological deformation; the unmodified rubber powder has limited improvement on the dynamic properties of asphalt, and insufficient fatigue resistance.

[0133] In comparative example 3, succinimide-modified rubber powder was added at one time, which resulted in insufficient mixing with the asphalt matrix, uneven modification effect, and poor flexibility of the asphalt matrix. During the one-time addition process, the modified rubber powder easily accumulated into agglomerates, which resulted in local enhancement, while other areas were not fully modified, resulting in decreased rheological properties of the material. Material inhomogeneity increased the probability of fatigue cracks in different parts, and cracks propagated faster.

[0134] In Comparative Example 4, due to the excessive addition of succinimide modified rubber powder, the elasticity is increased but the rigidity is insufficient, which easily leads to low-temperature cracking in an unbalanced state; in addition, it also leads to poor rheological properties, reduced rutting resistance, uneven material distribution, and accelerated crack initiation. In Comparative Example 5, due to excessive spraying of interface enhancer, the interface is too hard and loses flexibility, the interface synergy is weak, it is easy to crack, the fatigue resistance is poor, and the service life is shortened.

[0135] Comparative Example 6 uses a silane coupling agent. Compared with Example 1, the performance of its pavement material is poor. This is because: the organic phosphate contains a phosphoric acid group (-PO4 3- ), which has strong polarity and can bind to Ca on the surface of cement particles. 2+Chemical reactions occur to form strong chemical bonds (such as calcium phosphate complexes). This bonding force is strong and stable, and can significantly improve the bonding strength between cement particles and coupling agents. In addition, organic phosphate molecules usually carry organic segments (such as ester groups, alkyl groups or aromatic groups), which can form physical bonds and intermolecular forces (such as van der Waals forces) with organic components in asphalt (such as aromatic hydrocarbons or saturated hydrocarbons) to enhance the compatibility of cement and asphalt. Silane coupling agents mainly rely on the reaction of silanol (–Si–OH) with the surface of cement to form silanol bonds (–Si–O–). Although the bonding strength of silanol bonds is high, they are prone to partial hydrolysis in high humidity environments, resulting in a decrease in interfacial bonding strength.

[0136] The anti-rutting performance of the grouting material of Comparative Example 6 decreased after adding rubber powder. The reason is that in the semi-flexible pavement material, cement-based grouting is the main contributor to the rigid component; the addition of elastic crumb rubber increases the toughness of the grouting, but reduces its strength and stiffness. Therefore, under the same base asphalt mixture framework, the overall stiffness of the semi-flexible mixture containing crumb rubber modified grouting material is reduced. This makes the mixture more susceptible to rutting deformation.

[0137] Through the above analysis, it can be seen that the wet or dry process is recommended to add rubber powder as the modulus transition layer material of the semi-flexible composite pavement. Its low-temperature crack resistance, high-temperature rutting resistance, water damage resistance and fatigue performance are significantly improved, which improves the durability and comfort of the semi-flexible composite pavement.

[0138] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A semi-flexible composite pavement material based on a modulus transition layer, characterized in that: Includes large void matrix asphalt mixture and cement-based grouting mixture; The macrovoid matrix asphalt mixture comprises aggregate, mineral powder, succinimide modified rubber powder and SBS modified asphalt; The cement-based grouting mixture comprises a cement-based grouting material and water; In terms of weight, the pavement material includes 70-85 parts of large-void matrix asphalt mixture and 15-30 parts of cement-based grouting mixture; The mass ratio of the aggregate, mineral powder, succinimide modified rubber powder and SBS modified asphalt is 64-79.4:1-3:0.6-1:2-4, and the water-cement ratio of the cement-based grouting mixture is 0.3-0.32; The preparation method of the succinimide modified rubber powder comprises the following steps: S1, dissolving succinic acid and ammonia water in an ethanol solvent, heating the ammonia water and succinic acid to cause a cyclization reaction to generate succinimide; the mass ratio of succinic acid, ammonia water, and ethanol is 50-60:30-35:20-30, and the temperature of the cyclization reaction is 150° C.-200° C.; S2, transferring the rubber powder and succinimide into a mixer, reacting for 0.5-1h to obtain succinimide-modified rubber powder; the mass ratio of the rubber powder to succinimide is 1:0.8~1, the mixer is set to a stirring speed of 50~100 rpm, and a temperature of 150℃~180℃.

2. A semi-flexible composite pavement material based on a modulus transition layer as claimed in claim 1, characterized in that: The pavement material also includes an organic phosphate coupling agent, and 0.1-0.3 g of the organic phosphate coupling agent is sprayed per cubic meter of large-void matrix asphalt mixture.

3. A semi-flexible composite pavement material based on a modulus transition layer as claimed in claim 2, characterized in that: The organic phosphate coupling agent is one or more of triphenyl phosphate, tri(n-butyl) phosphate and tri(ethyl) phosphate.

4. A semi-flexible composite pavement material based on a modulus transition layer as claimed in claim 1, characterized in that: The aggregate is basalt aggregate with a particle size of ≤16mm; the mineral powder is limestone mineral powder with a particle size of ≤100μm; the rubber powder is powdered waste tires with a mesh size of 40-60 mesh; the cement-based grouting material is JGM-301 type semi-flexible pavement special cement-based grouting material, and the SBS modified asphalt is PG76-22 type modified asphalt.

5. Application of a semi-flexible composite pavement material based on a modulus transition layer as described in claim 2 in improving pavement crack resistance.

6. The use according to claim 5, characterized in that The pavement construction method includes the following steps: S1, on the basis of SBS modified asphalt, succinimide modified rubber powder is added in stages at 170-175°C to react, to prepare rubber modified asphalt, and then aggregate and mineral powder are added to mix, compacted and molded to obtain large-void matrix asphalt mixture; or the aggregate is heated to 170-175°C, and then mineral powder, succinimide modified rubber powder and SBS modified asphalt are added to mix, compacted and molded to obtain large-void matrix asphalt mixture; S2, mixing the cement-based grouting material with water and stirring evenly to obtain a cement-based grouting mixture; S3, after the test piece of step S1 is cooled to 50-60°C, an organic phosphate coupling agent is sprayed, and then a cement-based grouting mixture is poured in to obtain a semi-flexible composite pavement material test piece based on a modulus transition layer.

7. The use according to claim 6, characterized in that In step S1, the method of adding succinimide modified rubber powder in stages is: The first stage: 0-15min, add 20%~30% mass fraction of succinimide modified rubber powder, stirring speed is 4000~5000rpm; The second stage: 15-30min, add 40%~50% mass fraction of succinimide modified rubber powder, stirring speed is 4000~5000rpm; The third stage: 30-45 minutes, add the remaining succinimide modified rubber powder, and stir at a speed of 4000-5000 rpm.

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