Application of semi-flexible pavement material shear test method

Abstract

The invention discloses application of a semi-flexible pavement material shear test method, belongs to the technical field of transportation, and is applied to a semi-flexible pavement material cement-asphalt interface shear performance test, and the shear test method comprises the following steps: preparing a test matrix material; pouring the pre-heated asphalt on the surface of the prepared test matrix material; wrapping the test base material coated with the asphalt by using a wood block to manufacture a cement grouting material pouring mold; pouring a cement grouting material on the mold; curing, demolding and molding, and mounting a cushion block on one side of the cement grouting material; and carrying out a shear test on the prepared sample. By adopting the method, a special cement-asphalt interface shear test method is provided for a semi-flexible pavement material.

Description

Technical Field

[0001] The invention relates to the technical field of transportation, and in particular to an application of a shear test method for semi-flexible pavement materials. Background Art

[0002] Semi-flexible pavement material (SFPM) is a new type of pavement material that combines the advantages of asphalt pavement and cement concrete pavement. It is a composite of rigid cement grouting material and flexible asphalt mixture skeleton. The cement grouting material is filled in the pores inside the asphalt mixture, which greatly improves the asphalt mixture's ability to resist push deformation under high temperature conditions. It also has the advantages of excellent anti-rutting performance, high strength and modulus, oil resistance, acid resistance, heat resistance, and water resistance. At present, SFPM has been widely used in engineering as a means of repairing asphalt pavement rutting in road intersections, bus lanes and platforms, highway climbing sections, urban freight sections and other heavy-loaded and severely channelized sections, and has received widespread attention in recent years.

[0003] However, due to the large difference in performance between the cement grouting material and the asphalt binder of SFPM, this difference will lead to different fatigue cracking mechanisms of semi-flexible pavement materials under different conditions. In particular, under fatigue repeated loads, the weak part of the semi-flexible pavement material is inside the grouting material, which limits the application of semi-flexible pavement materials. Therefore, improving the shear resistance of the cement-asphalt interface is of great significance to ensure the durability of semi-flexible pavements.

[0004] At present, analysis of existing specifications, standards, and literature has not found a shear test method specifically for the cement-asphalt interface of semi-flexible pavement materials, which affects the actual application of semi-flexible pavement materials. Summary of the invention

[0005] The purpose of the present invention is to provide an application of a shear test method for semi-flexible pavement materials, which has solved the problems mentioned in the background technology.

[0006] To achieve the above object, the present invention provides an application of a shear test method for semi-flexible pavement materials, which is applied to the shear performance test of cement-asphalt interface of semi-flexible pavement materials. The shear test method includes:

[0007] S1. Prepare test matrix material;

[0008] S2, pouring the pre-heated asphalt onto the surface of the prepared test base material;

[0009] S3. After the asphalt film is cooled, a cement grouting material casting mold is made by wrapping the test base material coated with asphalt with a wooden block;

[0010] S4, pouring cement grouting material on the mold to make the cement grouting material bond with the asphalt membrane;

[0011] S5, curing and demoulding, and installing a pad on one side of the cement grouting material;

[0012] S6. Perform a shear test on the prepared specimen.

[0013] Preferably, the test matrix material is a metal bonding head or a basalt stone block, the metal bonding head specimen size is 20 mm in height, 40 mm in length, and 40 mm in width, and the basalt stone specimen size is a 40 mm cubic stone block.

[0014] Preferably, in step S2, the asphalt poured on the surface of the prepared test base material adopts a volume method to control the thickness, and the thickness is 200 μm.

[0015] Preferably, step S3 specifically includes:

[0016] Place the test substrate material coated with asphalt in an oven at the temperature required for heating the corresponding asphalt, and keep it warm for 30 minutes until the asphalt film is spread smoothly, then take it out and place it until it cools down;

[0017] After cooling, the test base material is tightly wrapped with small wooden boards with a width of 40 mm and fixed with tape to make a cement grouting casting mold.

[0018] Preferably, the height of the wooden boards around the cement slurry casting mold is 40 mm ± 1 mm higher than the test piece.

[0019] Preferably, in step S5, the mold is removed after being placed in a natural environment for 1 day, and the curing is continued until the age of 7 days. The cured specimen is placed in a thermal insulation environment box and the temperature is set to be kept warm for 3 hours.

[0020] Preferably, in step S5, the length and width of the cushion block are consistent with the size of the test matrix material.

[0021] Preferably, in step S6, the prepared specimen is placed on a 45° shearing mold, and a shear test is performed on a UTM universal testing machine at 25°C to calculate the shear strength, which is expressed as:

[0022]

[0023] Where, τ is the shear strength, MPa; F s is the shear failure load, N; S s is the stress-bearing area of ​​the specimen, m 2 .

[0024] Therefore, the present invention adopts the application of the above-mentioned shear test method for semi-flexible pavement materials and applies it to the cement-asphalt interface of semi-flexible pavement materials, providing a basis for the subsequent calculation of the shear strength of the cement-asphalt interface of semi-flexible pavement materials.

[0025] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flow chart of preparing cement-asphalt interface shear test specimens according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of a 45° shear test on a cement-asphalt interface according to an embodiment of the present invention;

[0028] Figure 3 A schematic diagram of cement-asphalt interface shear loading according to an embodiment of the present invention;

[0029] Reference numerals

[0030] 1. Metal bonding head; 2. Asphalt membrane; 3. Cement grouting material; 4. Pad; 5. Shearing mold. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] Example

[0033] The present invention provides an application of a semi-flexible pavement material shear resistance test method, which is applied to the semi-flexible pavement material cement-asphalt interface shear resistance test, referring to Figure 1 , shear test methods include:

[0034] S1. Prepare the test matrix material. The test matrix material can be a metal bonding head or a basalt stone. The metal bonding head specimen size is 20 mm high, 40 mm long, and 40 mm wide. The basalt stone specimen size is a 40 mm cubic stone.

[0035] S2. Pour the pre-heated asphalt onto the surface of the prepared test substrate material. Specifically, the asphalt poured onto the surface of the prepared test substrate material is controlled in thickness by a volume method, and the thickness is 200 μm. The volume method formula is:

[0036] m 沥青 =S×d×ρ;

[0037] Where: m is the asphalt mass, g; S is the specimen area, cm 2 ; d is the thickness of the asphalt film, cm; ρ is the density of asphalt, g / cm 3 .

[0038] It should be noted that the prepared test matrix material needs to be roughened with sandpaper to increase its adhesion with asphalt. Before paving, the surface of the prepared test matrix material needs to be cleaned with an ultrasonic cleaner and the cleaned test matrix material needs to be placed in an oven.

[0039] S3. After the asphalt film has cooled, a cement grouting casting mold is made by wrapping the asphalt-coated test base material with a wooden block.

[0040] Specifically, first, the test substrate material coated with asphalt is placed in an oven at the temperature required for heating the corresponding asphalt, and kept warm for 30 minutes until the asphalt film is spread smoothly, and then taken out and placed until cooled.

[0041] Then, the cooled test base material is tightly wrapped with a small wooden board with a width of 40 mm and fixed with adhesive tape to make a cement grouting material casting mold. The height of the wooden boards around the cement slurry casting mold is 40 mm ± 1 mm higher than the test piece.

[0042] S4. Pour cement grouting material on the mold to make the cement grouting material bond with the asphalt membrane.

[0043] Specifically, pre-mixed cement grouting material is poured into the groove of the mold.

[0044] S5. Maintain and demould the mold, and install a pad on one side of the cement grouting material.

[0045] Specifically, after being placed in the natural environment for 1 day, the mold is removed and the curing is continued until the 7-day age. The cured specimen is placed in a heat preservation environment box and the temperature is set to be kept warm for 3 hours. After the curing is completed, a pad is installed on one side of the cement grouting material, and the length and width of the pad are consistent with the size of the test matrix material.

[0046] S6. Perform a shear test on the prepared specimen.

[0047] Specifically, the prepared specimen is placed on a 45° shearing die, and a shear test is performed on a UTM universal testing machine to calculate the shear strength. The shear strength is expressed as:

[0048]

[0049] Where, τ is the shear strength, MPa; F sis the shear failure load, N; S s is the stress-bearing area of ​​the specimen, m 2 .

[0050] In order to verify the effectiveness of the method of the present invention, a metal bonding head 1 was selected as the test base material. The size of the metal bonding head 1 was 20 mm in height, 40 mm in length, and 40 mm in width. It was roughened with 120-grit sandpaper to increase its adhesion with asphalt.

[0051] Put the metal bonding head 1 into an oven at the temperature required for heating the corresponding asphalt for standby use. Use 70# base asphalt, SBS modified asphalt, and high viscosity modified asphalt to prepare them in the oven for standby use. Take out the rock specimen and place it on an electronic scale. Pour the pre-heated asphalt on the metal bonding head. Use the volume method to control the thickness of the asphalt film 2 to 200μm. Calculate the required asphalt mass according to the formula as shown below:

[0052] m 70#基质沥青 =S×d×ρ=4×4×0.02×1.035=0.331(g);

[0053] m SBS沥青 =S×d×ρ=4×4×0.02×1.029=0.329(g);

[0054] m 高黏沥青 =S×d×ρ=4×4×0.02×1.045=0.334(g);

[0055] Put the metal bonding head coated with asphalt into an oven at the temperature required for heating the asphalt for 30 minutes until the asphalt film 2 is spread smoothly, take it out and place it until it cools to room temperature for use.

[0056] Use wood blocks to wrap the test base material coated with asphalt to make a cement grouting material casting mold, pour the pre-mixed cement grouting material 3, and cure and demould to form. Place the cured specimen in an insulation environment box for insulation, and set the temperature for insulation for 3 hours.

[0057] The pad 4 is glued to one side of the cement grouting material 3. After the specimen is prepared, the specimen is placed on a 45° shearing mold 5. Figure 2 As shown in the figure, a shear test was performed using a UTM universal testing machine at 25°C. Figure 3 The shear strength results are shown in Table 1.

[0058] Table 1 Interface shear strength of different cement types with asphalt at 25°C

[0059]

[0060] Therefore, the present invention adopts the above-mentioned shear test method and applies it to the shear performance test of the cement-asphalt interface of semi-flexible pavement materials, providing a basis for calculating the shear strength of the cement-asphalt interface of semi-flexible pavement materials in practice.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. Application of a shear test method for semi-flexible pavement materials, characterized in that: Applied to the shear performance test of cement-asphalt interface of semi-flexible pavement materials. The shear test methods include: S1. Prepare test matrix material; S2, pouring the pre-heated asphalt onto the surface of the prepared test base material; S3. After the asphalt film is cooled, a cement grouting material casting mold is made by wrapping the test base material coated with asphalt with a wooden block; S4, pouring cement grouting material on the mold to make the cement grouting material bond with the asphalt membrane; S5, curing and demoulding, and installing a pad on one side of the cement grouting material; S6. Perform a shear test on the prepared specimen.

2. The application of the shear test method for semi-flexible pavement materials according to claim 1 is characterized in that: The test matrix material is a metal bonding head or a basalt stone block. The metal bonding head specimen has a size of 20 mm in height, 40 mm in length and 40 mm in width. The basalt stone specimen has a size of 40 mm in cubic stone.

3. Application of the shear test method for semi-flexible pavement materials according to claim 1, characterized in that: In step S2, the asphalt poured on the surface of the prepared test base material is controlled in thickness by a volume method, and the thickness is 200 μm.

4. Application of the shear test method for semi-flexible pavement materials according to claim 1, characterized in that: Step S3 specifically includes: Place the test substrate material coated with asphalt in an oven at the temperature required for heating the corresponding asphalt, and keep it warm for 30 minutes until the asphalt film is spread smoothly, then take it out and place it until it cools down; After cooling, the test base material is tightly wrapped with small wooden boards with a width of 40 mm and fixed with tape to make a cement grouting casting mold.

5. The application of the shear test method for semi-flexible pavement materials according to claim 4 is characterized in that: The height of the wooden boards around the cement slurry casting mold is 40mm±1mm higher than the test piece.

6. The application of the shear test method for semi-flexible pavement materials according to claim 1 is characterized in that: In step S5, the samples are placed in a natural environment for 1 day before demoulding and continued to be cured until the age of 7 days. The cured samples are placed in a heat preservation environment box and the temperature is set to be kept warm for 3 hours.

7. The application of the shear test method for semi-flexible pavement materials according to claim 1, characterized in that: In step S5, the length and width of the pad block are consistent with the size of the test base material.

8. The application of the shear test method for semi-flexible pavement materials according to claim 1 is characterized in that: In step S6, the prepared specimen is placed on a 45° shearing mold, and a shear test is performed on a UTM universal testing machine at 25°C to calculate the shear strength. The shear strength is expressed as: Where, τ is the shear strength, MPa; F s is the shear failure load, N; S s is the stress-bearing area of ​​the specimen, m 2 .

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