Simulation method for interface phase contribution rate of semi-flexible pavement cement asphalt composite material

Abstract

The application discloses a simulation method for interface phase contribution rate of semi-flexible pavement cement asphalt composite material, and belongs to the technical field of semi-flexible pavement. The method comprises the following steps: simulating and constructing a cement-based three-dimensional network structure with a certain target porosity; preparing a macropore matrix asphalt mixture with the same target porosity, and preparing a semi-flexible pavement material through cement grouting; after curing, respectively testing the properties of the cement-based three-dimensional network structure, the macropore matrix asphalt mixture and the semi-flexible pavement material; and according to the mechanical property test results of the cement-based three-dimensional network structure, the macropore matrix asphalt mixture and the semi-flexible pavement material, analyzing and calculating the matrix phase contribution rate of the asphalt mixture, the cement-based phase contribution rate and the cement-asphalt interface phase contribution rate.

Description

Technical Field

[0001] This invention belongs to the field of semi-flexible pavement technology, specifically relating to a method for simulating the interfacial phase contribution rate of cement asphalt composite materials for semi-flexible pavements. Background Technology

[0002] Semi-flexible pavements, due to their excellent rutting resistance, are widely used in road sections prone to rutting, such as intersections, BRT lanes, and intelligent rail transit. They are constructed by injecting cement-based materials into large-pore asphalt mixtures to form a three-dimensional interpenetrating network structure. The interaction between the two phases effectively resists shear deformation caused by loads. However, existing research on the interaction between the cement-based three-dimensional network structure and the asphalt skeleton is not in-depth. The influence of the cement-based three-dimensional network structure on the compressive strength, flexural tensile deformation capacity, and shear strength of composite specimens remains unclear, and there is a lack of effective and reliable methods to obtain the relevant performance characteristics. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for simulating the interfacial phase contribution rate of semi-flexible pavement cement asphalt composite materials.

[0004] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0005] On the one hand, the present invention provides a method for simulating the interfacial phase contribution rate of semi-flexible pavement cement asphalt composite materials, characterized by comprising the following steps:

[0006] Simulate and construct a cement-based three-dimensional network structure with a certain target porosity;

[0007] Prepare large-pore matrix asphalt mixtures with the same target porosity, and prepare semi-flexible pavement materials by cement grouting;

[0008] After curing, mechanical performance tests were conducted to obtain the mechanical performance indicators of cement-based three-dimensional network structure, macroporous matrix asphalt mixture and semi-flexible pavement material, respectively.

[0009] Based on the mechanical properties of cement-based three-dimensional network structures, large-pore matrix asphalt mixtures, and semi-flexible pavement materials, the contribution rates of the matrix phase, cement-based phase, and cement-asphalt interface phase in asphalt mixtures were analyzed and calculated.

[0010] As a further improvement, the method steps for simulating the construction of cement-based three-dimensional network structures are as follows:

[0011] Select the target porosity of the asphalt mixture matrix to be simulated;

[0012] Select one or more lightweight plastic spheres of different diameters based on the maximum nominal particle size and particle size distribution characteristics of the semi-flexible pavement material;

[0013] Based on the selected target porosity and the mold with a top opening, place an appropriate number of lightweight plastic spheres into the mold, and cover the top opening of the mold with a metal screen with a aperture smaller than the diameter of the spheres.

[0014] The prepared cement-based grout is poured into a mold through a metal screen and cured to form a cement-based three-dimensional network structure that simulates a certain target porosity.

[0015] As a further improvement, the analytical calculation method for the phase contribution rate at the cement-asphalt interface includes:

[0016] The mechanical performance index E of the cement-based three-dimensional network structure was obtained respectively. G Mechanical property index E of macroporous matrix asphalt mixture A Mechanical performance index E of semi-flexible pavement materials C ;

[0017] The contribution rate of the matrix phase in asphalt mixture is calculated using the following formula:

[0018]

[0019] Contribution rate of cement-based phase:

[0020]

[0021] Based on the contribution rates of the matrix phase and the cement-based phase in asphalt mixtures, the contribution rate of the cement-asphalt interface phase is calculated as follows:

[0022] k I =1-k A -k G .

[0023] As a further improvement, the formula for calculating the number of lightweight plastic spheres is as follows:

[0024]

[0025] In the formula, the target porosity is represented by δ, and the number of spheres is represented by N. i The diameter of a sphere is represented by r. i The total volume of the mold is represented by V.

[0026] As a further improvement, the mold adopts a three-piece mold for cement mortar, and the molded specimen is 160mm long, 40mm high, and 40mm wide.

[0027] The mesh size of the metal screen is 4.75 mm;

[0028] The lightweight plastic spheres are made of foam plastic or polypropylene with a diameter of 10 mm.

[0029] As a further improvement, the coarse aggregate particle size of the macroporous matrix asphalt mixture is the same as the diameter of the lightweight plastic spheres.

[0030] As a further improvement, the cement grouting material includes water, cement, fine sand, admixtures, and fillers.

[0031] As a further improvement, the mechanical property test includes compressive strength test, flexural strength test, and various tests that can be performed on the specimen formed by the mold.

[0032] Compared with existing technologies, the method for simulating the interfacial phase contribution rate of semi-flexible pavement cement asphalt composite materials provided by this invention has the following technical advantages:

[0033] 1. It can effectively and reliably evaluate the mechanical properties of cement-based three-dimensional network structures in semi-flexible pavements corresponding to different matrix asphalt mixture void ratios, providing guidance for the design and selection of grouting materials for semi-flexible pavements;

[0034] 2. Lightweight plastic balls of different diameters can be used to simulate different gradation combinations, more realistically simulating the distribution of cement-based materials in the asphalt mixture skeleton;

[0035] 3. Based on the preparation of cement-based three-dimensional network structure specimens, the mechanical properties of the cement phase of semi-flexible pavement can be tested, thus providing a basis for calculating the contribution rates of the asphalt matrix phase, cement phase and interface phase, and providing ideas and directions for material design and performance control. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of a cement-based three-dimensional network structure after a specimen has been cast in a mold, as provided in an embodiment of the present invention.

[0037] In the picture:

[0038] 1. Specimen mold; 2. Lightweight plastic spheres; 3. Cement-based grouting material. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0040] like Figure 1 As shown, the method for simulating the interfacial phase contribution rate of semi-flexible pavement cement asphalt composite materials provided by the present invention firstly selects one or more lightweight plastic spheres of different sizes according to the maximum nominal particle size and particle size distribution characteristics of the semi-flexible pavement material.

[0041] Secondly, calculate the number N of lightweight plastic spheres according to the target porosity.i Then N i A lightweight plastic sphere is placed in mold 1, and the top is covered with a metal mesh.

[0042] Finally, the prepared cement-based grout 3 is poured into the mold through a sieve.

[0043] Simultaneously, large-pore asphalt mixtures with the same target porosity are prepared, and semi-flexible pavement materials are prepared by cement grouting. After curing, mechanical performance tests are conducted on different specimens, including compressive strength tests, flexural strength tests, and various tests that can be performed on specimens formed by molds.

[0044] Example 1

[0045] Plastic foam spheres with a diameter of 1cm and a target porosity of 24% were selected. A total of 370 spheres were used. The spheres were placed in a cylindrical mold (mold radius of 100mm and height of 63.5mm) and a 4.75mm mesh screen was placed on top of the mold. Cement-based grouting material (compressive strength of 30MPa and flexural strength of 5MPa) was poured into the mold through the screen.

[0046] After three days of curing, the above specimens were subjected to an indirect tensile test, and the splitting strength was 0.23 MPa.

[0047] Simultaneously, a large-pore asphalt mixture with the same porosity is formed and grouted to prepare a semi-flexible pavement material.

[0048] Three days after curing, a splitting test was conducted, and the splitting strength of the large-pore asphalt mixture was 0.49 MPa, while the splitting strength of the semi-flexible pavement material was 1.72 MPa.

[0049] Based on the above mechanical property test results, the following analysis and calculations are performed:

[0050] The contribution rate of the asphalt matrix phase in the semi-flexible pavement cement-asphalt composite material is 28.5%.

[0051] The contribution rate of the cement-based phase was 13.4%;

[0052] The contribution rate of the cement-asphalt interface phase is (1-28.5%-13.4%)=58.1%.

[0053] Example 2

[0054] Plastic foam spheres with a diameter of 0.5cm were selected, with a target porosity of 24%. A total of 2940 spheres were used. The spheres were placed in a cylindrical mold (mold radius of 100mm and height of 63.5mm), and a 4.75mm mesh screen was placed on top of the mold. Cement-based grouting material (compressive strength of 35MPa and flexural strength of 6MPa) was poured into the mold through the screen.

[0055] Three days after curing, the specimens were taken for anti-scattering performance testing, and the scattering loss was 47%.

[0056] Simultaneously, a large-pore asphalt mixture with the same porosity is formed and grouted to prepare a semi-flexible pavement material.

[0057] Three days after curing, a scattering test was conducted, and the scattering loss of the large-pore asphalt mixture was 100%, while the scattering loss of the semi-flexible pavement material was 19%.

[0058] Based on the above mechanical property test results, the following analysis and calculations are performed:

[0059] The contribution rate of the asphalt matrix phase in the cement-asphalt composite material for semi-flexible pavement is 0%.

[0060] The cement phase contribution rate is 65%;

[0061] The contribution rate of the cement-asphalt interface phase is (1-0%-65%)=35%.

[0062] The test results from the above embodiments show that the sum of the splitting strength of the cement-based network structure and the splitting strength of the asphalt matrix skeleton is less than the splitting strength of the semi-flexible pavement material, indicating that ignoring the role of the interface phase will underestimate the mechanical properties of the composite material. This invention, however, provides guidance for the design and selection of grouting materials for semi-flexible pavements by assessing the mechanical properties of the cement phase in semi-flexible pavements. It enables the testing of the mechanical properties of the cement phase in semi-flexible pavements, thereby providing a basis for calculating the contribution rates of the asphalt matrix phase, cement phase, and interface phase, and ultimately providing ideas and directions for material design and performance control.

[0063] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for simulating the interfacial phase contribution rate of semi-flexible pavement cement asphalt composite materials, characterized in that, Includes the following steps: Simulate and construct a cement-based three-dimensional network structure with a certain target porosity; Prepare large-pore matrix asphalt mixtures with the same target porosity, and prepare semi-flexible pavement materials by cement grouting; After curing, mechanical properties of cement-based three-dimensional network structure, macroporous matrix asphalt mixture and semi-flexible pavement material were obtained through testing. Based on the mechanical property test results of cement-based three-dimensional network structure, large-pore matrix asphalt mixture and semi-flexible pavement material, the contribution rate of the matrix phase, cement-based phase and cement-asphalt interface phase of asphalt mixture are analyzed and calculated. The method and steps for simulating the construction of cement-based three-dimensional network structures are as follows: Select the target porosity of the asphalt mixture matrix to be simulated; Select one or more lightweight plastic spheres of different diameters based on the maximum nominal particle size and particle size distribution characteristics of the semi-flexible pavement material; Based on the selected target porosity and the mold with a top opening, place an appropriate number of lightweight plastic spheres into the mold, and cover the top opening of the mold with a metal screen with a aperture smaller than the diameter of the spheres. The prepared cement-based grout is poured into a mold through a metal screen and cured to form a cement-based three-dimensional network structure for simulating a certain target porosity. The formula for calculating the number of lightweight plastic spheres is as follows: ； In the formula, the target porosity is expressed as: The number of spheres is expressed as N i The diameter of a sphere is expressed as r i The total volume of the mold is expressed as V .

2. The method for simulating the interfacial phase contribution rate of semi-flexible pavement cement asphalt composite materials according to claim 1, characterized in that, The analytical calculation methods for the contribution rate of the cement-asphalt interface phase include: Obtain the mechanical properties of cement-based three-dimensional network structures respectively E G Mechanical properties of macroporous matrix asphalt mixtures E A Mechanical properties of semi-flexible pavement materials E C ; The contribution rate of the matrix phase in asphalt mixture is calculated using the following formula: ； Contribution rate of cement-based phase: ； Based on the contribution rates of the matrix phase and the cement-based phase in asphalt mixtures, the contribution rate of the cement-asphalt interface phase is calculated as follows: 。 3. The method for simulating the interfacial phase contribution rate of semi-flexible pavement cement asphalt composite materials according to claim 2, characterized in that, The mechanical property tests also include compressive strength tests and flexural strength tests.

4. The method for simulating the interfacial phase contribution rate of semi-flexible pavement cement asphalt composite materials according to claim 3, characterized in that, The mold is a three-piece mold for cement mortar. The mesh size of the metal screen is 4.75 mm; The lightweight plastic spheres are made of foam plastic or polypropylene with a diameter of 10 mm.

5. The method for simulating the interfacial phase contribution rate of semi-flexible pavement cement asphalt composite materials according to claim 4, characterized in that, The coarse aggregate particle size of the macroporous matrix asphalt mixture is the same as the diameter of the lightweight plastic spheres.

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