CN108469389A - A kind of road surface interlayer cementing effect evaluation method based on composite beam fatigue test - Google Patents

Abstract

The invention relates to a method for evaluating the bond effect between pavement layers based on a composite beam fatigue test, comprising the following steps: step 1: performing mix ratio design and performance verification on asphalt mixture; step 2: calculating the required The quality of the asphalt mixture and the coating amount of the adhesive layer; Step 3: Forming and curing of composite beam specimens; Step 4: Fatigue performance test of the cured composite beam specimens; Step 5: Analysis and comparative evaluation of test data. This application evaluates the performance of the adhesive layer in the pavement structure combination. By evaluating the effect of the adhesive layer on the fatigue life of the asphalt pavement surface layer, and then comprehensively evaluates the interlayer bonding effect, it provides a basis for the selection of adhesive layer materials and reduces Pavement diseases caused by improper material selection can reduce economic losses.

Description

A Method for Evaluation of Pavement Interlayer Bonding Effect Based on Composite Beam Fatigue Test

technical field

The invention belongs to the technical field of road material engineering, and relates to a method for evaluating the bonding effect of pavement interlayers based on composite beam fatigue tests.

Background technique

Asphalt pavement adhesive layer is a thin layer of asphalt spread to strengthen the bonding of each layer of asphalt pavement to form a continuous whole. The quality of the interlayer bonding effect directly affects the service life of the asphalt pavement. In the design method of asphalt pavement in our country, it is assumed that the interlayer is completely continuous, but due to improper interlayer treatment measures, delamination and slippage are often prone to occur between asphalt pavement surface layers, making it a weak link in the pavement structure and weakening the pavement. The overall resistance of the structure is accompanied by repeated loads, as well as unfavorable conditions such as freezing and thawing, high temperature, etc., which can easily cause damage such as cracking of the pavement. Relevant requirements for adhesive layer materials are mentioned in the specification, but the regulations are relatively simple, most of which only involve the own requirements of adhesive layer materials, and lack the performance evaluation of adhesive layer in pavement structure combination. When ordinary scholars study the performance of adhesive layer materials in the pavement structure combination, they often focus on the two aspects of interlayer shear strength and pull-out strength, ignoring the influence of adhesive layer materials on the fatigue resistance of the overall structure of the surface layer.

The invention patent with the patent application number 201510795294.6 discloses a method for evaluating the bond strength and durability between layers of asphalt pavement. The 45° oblique shear specimen and the cylindrical specimen are formed respectively, and the 25, Calculate the maximum failure load at 40 and 60°C and calculate the shear strength value to obtain the shear strength ratio. The oblique shear specimen is loaded according to a fixed value of 0.2 to 0.7 times the maximum failure load. The load is loaded with a haversine waveform, and the loading frequency is 10 Hz. Repeat the loading until the specimen is destroyed. When the specimen is destroyed, the corresponding The number of loading times is the structural life under this stress level. This evaluation method is simple and easy to operate, and is of great significance to the evaluation of the bonded shear resistance between asphalt pavement layers. However, this patent also ignores the influence of the adhesive layer material on the fatigue resistance of the overall structure of the surface layer.

The invention patent with the patent application number 201410027525.4 discloses a method for evaluating the shear resistance of asphalt sand and modified asphalt sand bridge deck pavement waterproof adhesive layer. Under the conditions, take out the cement concrete specimen with the design label size of 300mm×300mm×50mm that has been cured for 28 days and dried. The bridge deck pavement layer asphalt mixture is rolled and formed into shear composite specimens, cut into specimens of specified size along the rolling direction, and subjected to freeze-thaw cycle tests. One set of specimens is not vacuum-saturated with water, and the other set of specimens Put the specimens into a plastic bag after being vacuum-saturated with water, add about 15mL of water, freeze at -18°C for 16 hours, then immediately put them in a constant temperature water tank at 60°C, and keep them warm for 24 hours. Both groups of test pieces are immersed in a constant temperature water tank at 60°C Less than 2h; carry out the shear test, calculate the freeze-thaw cycle shear strength ratio RSR, RSR is required to be ≥ 85%, and this patent also ignores the influence of the adhesive layer material on the fatigue resistance of the overall structure of the surface layer.

Contents of the invention

In order to overcome the deficiencies in the prior art, the present invention provides a method for evaluating the bonding effect between layers of pavement based on composite beam fatigue tests. The bonding effect provides a basis for the selection of adhesive layer materials, reduces road surface diseases caused by improper selection of interlayer materials, and reduces economic losses.

The present invention provides following technical scheme:

A method for evaluating the bonding effect between pavement layers based on composite beam fatigue tests, comprising the following steps:

Step 1: Proportion design and performance verification of asphalt mixture;

Step 2: Calculate the quality of asphalt mixture and the coating amount of adhesive layer required for forming composite beam specimens;

Step 3: Forming and curing of composite beam specimens;

Step 4: Fatigue performance test of the well-cured composite beam specimen;

Step 5: Analysis and comparative evaluation of test data.

Preferably, in step 1, the asphalt mixture is divided into the asphalt mixture used for the upper layer and the asphalt mixture used for the lower layer.

In any of the above schemes, preferably, the asphalt mixture used in the upper layer is double-modified lake asphalt (lake asphalt-SBS) AC-13 type asphalt mixture.

For any of the above schemes, it is preferred that the asphalt mixture used in the lower layer is of warm-mix SBS modified AC-20C type.

Preferably, in any of the above schemes, in step 2, the mass of the asphalt mixture is calculated according to the required volume and the measured density.

Preferably, in any of the above schemes, the molding and health preservation method in step 3 includes the following steps;

(1) Use the test mold to make the shaped beam test piece;

(2) Cut the formed beam test piece into a fatigue test piece, and the adhesive layer is in the middle of the fatigue test piece;

(3) Put the fatigue specimens into the environmental chamber for health preservation.

Preferably, in any of the above schemes, the shaped beam test piece in step (1) includes an upper layer and a lower layer, and an adhesive layer is arranged between the upper layer and the lower layer.

Preferably, in any of the above schemes, the sticky layer material is selected from at least one of SBS modified asphalt, rubber asphalt and emulsified asphalt.

In any of the above schemes, it is preferred that SBS modified asphalt is selected as the sticky layer material.

Preferably, in any of the above schemes, rubber asphalt is selected as the sticky layer material.

Preferably, in any of the above schemes, the sticky layer material is emulsified asphalt.

Preferably, in any of the above schemes, the size of the inner wall of the test mold in step (1) is 150mm×150mm×550mm.

It is preferred that any of the above-mentioned schemes is that the concrete method for making the molded composite beam specimen in the step (1) is as follows:

(A) First brush the inside of the test mold with oil, and put the lower pressure block on the lower part of the test mold, exposing a part, then brush the backing plate with oil and put it on the lower pressure plate;

(B) Fill the lower layer into the test mold with asphalt mixture several times, then spread the sticky layer of asphalt, fill the upper layer with asphalt mixture into the test mold several times, and finally put the upper compact into the test mold Inner, exposed part;

(C) Put the whole trial mold on the press, pressurize until the upper and lower briquetting blocks are pressed into the trial mold, and maintain the pressure for 5 minutes;

(D) Remove the test mold after releasing the pressure, let it cool down to room temperature, and then remove the mold.

In any of the above schemes, it is preferred that the parts of the upper pressing block and the lower pressing block exposed outside the test mold are equal.

Preferably, in any of the above schemes, in step (2), the formed beam specimen is cut into fatigue specimens of 380mm×50mm×63.5mm by cutting equipment, and the adhesive layer is at the center of the height of the fatigue specimen.

Preferably, in any of the above schemes, in step (3), the curing temperature is 15°C±0.5°C, and the curing time is more than 4 hours.

Preferably, any of the above schemes is that step 4: the specific method of fatigue performance test is: put the cured composite beam specimen into the four-point bending fatigue loading device, the loading frequency is 10Hz±0.1Hz, and the constant strain control method is adopted. The fatigue test was carried out in the continuous biased sinusoidal loading mode; the test termination condition was the number of loading cycles corresponding to the bending stiffness modulus reduced to 50% of the initial bending stiffness modulus.

Beneficial effect:

The invention provides a method for evaluating the bonding effect between pavement layers based on a composite beam fatigue test, comprising the following steps:

Step 1: Proportion design and performance verification of asphalt mixture;

Step 2: Calculate the quality of asphalt mixture and the coating amount of adhesive layer required for forming composite beam specimens;

Step 3: Forming and curing of composite beam specimens;

Step 4: Fatigue performance test of the well-cured composite beam specimen;

Step 5: Analysis and comparative evaluation of test data. The fatigue performance test is a four-point bending fatigue life test of asphalt mixture, using a four-point bending fatigue loading device to measure the fatigue life of the compacted mixture under repeated bending loads under specified test conditions. On the basis of the four-point bending fatigue life test, a composite beam specimen with an upper layer and a lower layer, and an adhesive layer between the upper layer and the lower layer is formed, and the fatigue performance test of the composite beam is carried out to evaluate the effect of the adhesive layer material on the asphalt pavement surface layer. Influence of fatigue life and evaluation of interlayer bonding effect.

This application evaluates the performance of the adhesive layer in the pavement structure combination. By evaluating the effect of the adhesive layer on the fatigue life of the asphalt pavement surface layer, and then comprehensively evaluates the interlayer bonding effect, it provides a basis for the selection of adhesive layer materials and reduces Pavement diseases caused by improper material selection can reduce economic losses.

Description of drawings:

Fig. 1 is a cross-sectional view of a formed composite beam specimen produced in the method for evaluating the bonding effect between asphalt pavement layers based on the composite beam fatigue test in Example 1 of the present invention.

Detailed ways

In order to further understand the technical characteristics of the present invention, the present invention will be described in detail below in conjunction with specific embodiments. The embodiment is only exemplary to the present invention, and does not have any restrictive effect. Any insubstantial modification made by those skilled in the art on the basis of the present invention shall belong to the protection scope of the present invention.

Example 1

The bonding effect evaluation method between asphalt pavement layers based on composite beam fatigue test adopted by the present invention comprises the following steps:

1) In accordance with JTG E51-2009 "Test Regulations for Inorganic Binder Stable Materials in Highway Engineering" T0844-2009 Inorganic Binder Stable Material Specimen Manufacturing Method (Beam Type) to form a composite beam specimen, the structure of the composite beam specimen is shown in Figure 1 As shown, the size of the inner wall of the selected test mold is 150mm×150mm×550mm.

When forming composite beam specimens (i.e., composite beam specimens), attention should be paid to the order of adding asphalt mixture. With reference to the actual pavement structure, the amount of asphalt mixture used for the upper layer 1, the amount of asphalt mixture used for the lower layer 2, and the viscosity of the asphalt mixture should be calculated in advance. The amount of layer 3 is formed by a press during molding. The quality of the asphalt mixture is calculated according to the required volume and the measured density. The height of the upper layer 1 and the lower layer 2 of the composite beam after compaction is both 30mm, and the amount of the adhesive layer is the optimal coating amount (for example, the SBS modified asphalt adhesive layer is the most The best coating amount is 1.4kg/m ² , the best coating amount of emulsified asphalt sticky course is 0.5kg/m ² , and the best coating amount of rubber asphalt sticky course is 1.8kg/m ² ).

First, oil the inside of the test mold, and put the lower pressure block on the lower part of the test mold, about 2cm exposed, and then brush the backing plate with oil and put it on the lower pressure plate. Fill the calculated lower layer 2 with asphalt mixture into the test mold in 2 to 3 times. After each filling, tamp it evenly with a tamping rod to make the surface smooth, and then spread the asphalt material for the sticky layer 3. The calculated The upper layer 1 of the upper layer is filled into the test mold with asphalt mixture in 2 to 3 times. After each filling, it is evenly tamped with a tamping stick. Finally, the upper briquetting block is put into the test mold, and it should also be exposed by about 2cm (upper layer). The part of the pressing block and the lower pressing block exposed outside the test mold should be equal). Put the whole trial mold (together with the upper briquetting block and the lower briquetting block) on the press, pressurize until both the upper briquetting block and the lower briquetting block are pressed into the trial mold, and maintain the pressure for 5 minutes. After releasing the pressure, remove the test mold, let it cool down to room temperature (not less than 12 hours), and then use the method of disassembling the mold to demould.

2) Using cutting equipment to cut into fatigue specimens

Cut the formed 150mm×150mm×550mm composite beam specimen with a cutting machine into a 380mm×50mm×63.5mm fatigue specimen, and the position of the adhesive layer 3 is in the middle of the formed composite beam specimen. The length is 380mm±5mm, the thickness is 50mm±5mm, and the width is 63.5±5mm. When cutting, the cutting position should be carefully measured to ensure that the position of the adhesive layer 3 is in the middle layer of the composite beam.

3) The four-point bending fatigue life test is carried out by using the formed composite beam specimen to determine the fatigue life of the composite beam.

Put the composite beam specimen into the environmental chamber for health preservation, and keep it under the condition of 15°C±0.5°C for more than 4 hours before the test can be carried out.

Using a four-point bending fatigue loading device, under specified test conditions, the fatigue life of the compacted mixture subjected to repeated bending loads was determined. Put the cured composite beam specimen into the four-point bending fatigue loading device, the loading frequency is 10 Hz ± 0.1 Hz, and the fatigue test is carried out in the continuous partial sinusoidal loading mode controlled by constant strain. The test termination condition is the number of loading cycles corresponding to the bending stiffness modulus decreasing to 50% of the initial bending stiffness modulus. For the same structure combination, at least 3 parallel tests shall be carried out under the same test conditions.

The composite beam specimen specifically includes an upper layer 1 and a lower layer 2, and an adhesive layer 3 is arranged between the upper layer 1 and the lower layer 2. The upper layer 1 uses lake asphalt double-modified (lake asphalt-SBS) AC-13 asphalt mixture, and the mix ratio of lake asphalt double-modified AC-13 is shown in Table 1; the lower layer 2 uses warm-mix SBS modified AC-20C The gradation of warm-mix SBS modified AC-20C is shown in Table 2; the adhesive layer 3 is made of any one of SBS modified asphalt, rubber asphalt and emulsified asphalt to make composite beam specimens respectively, and emulsified asphalt is used to make adhesive For layer 3, it is necessary to wait until the emulsified asphalt is demulsified before filling the upper layer 1 with asphalt mixture.

By comparing the fatigue performance of composite beam specimens with adhesive layer 3 of different materials, and using the accelerated aging method of asphalt mixture, that is, the short-term aging method is to put the asphalt mixture specimen in an oven at 135°C and heat it under ventilation for 4 hours ; The method of long-term aging is to first aging the asphalt mixture for a short period of time, then forming the test piece, demoulding after cooling, placing the test piece in an oven at 85°C, and heating continuously for 5 days. The effect of surface course and sticky course 3 aging on the fatigue performance of asphalt mixture was studied.

The results obtained through washing and screening of various mineral materials are adopted and according to the "Technical Specifications for Highway Asphalt Pavement Construction" JTG F40-2004 Zhonghu asphalt double-modified AC-13 type and warm-mixed AC-20C gradation requirements, this paper The upper layer 1 of the application adopts lake asphalt double-modified AC-13 type asphalt mixture, and the gradation ratio is shown in the following table 1:

Table 1 Lake asphalt double-modified AC-13 gradation ratio

The above is the amount of aggregate, which includes the ratio of ore and asphalt.

The lower layer 2 of this application uses warm-mix SBS modified AC-20C type asphalt mixture, and the gradation of warm-mix AC-20C is shown in Table 2:

Table 2 Mixing ratio of warm mix SBS modified AC-20C asphalt mixture

According to the above-mentioned method for forming beam specimens, the upper layer 1 of lake asphalt double-modified AC-13 type, the lower layer 2 and adhesive layer 3 of warm-mixed AC-20C type are sequentially formed, and then cut into lengths by using a cutting machine. A standard composite beam specimen with a thickness of 380mm±5mm, a thickness of 50mm±5mm, and a width of 63.5±5mm.

In order to study the effect of the aging of the surface layer and the adhesive layer 3 on the fatigue performance of the composite beam, three groups of experiments were set up in this experiment, namely, the fatigue test of the unaged composite beam of the surface layer and the adhesive layer 3, and the short-term aging of the surface layer and the adhesive layer 3. Composite beam fatigue test and composite beam fatigue test of long-term aging of surface layer and adhesive layer 3. In the experiment, the adhesive layer was simulated by rotating thin film oven test (RTFOT) for short-term aging, and pressure aging test (PAV) was used to simulate long-term aging.

A four-point bending fatigue test was carried out on the surface layer, and the test results are shown in Table 3:

Table 3 Surface layer fatigue life data

A four-point bending fatigue test was carried out on the composite beam, and the experimental results are shown in Table 4:

Table 4 fatigue test results

From the experimental results in Table 3 and Table 4, it can be seen that the fatigue life of the composite beam with long-term aging of the surface layer and the adhesive layer 3 is seriously attenuated, and its fatigue performance is far from meeting the specifications. In addition, the fatigue life of composite beams is also related to the materials used in the adhesive layer 3. As shown in Table 4, the fatigue life of composite beams using different adhesive layer 3 materials is in the order: SBS modified asphalt > rubber asphalt > emulsified asphalt.

Claims (10)

1. a method for evaluating the bonding effect between pavement layers based on composite beam fatigue test, is characterized in that: comprise the steps: Step 1: Proportion design and performance verification of asphalt mixture; Step 2: Calculate the quality of asphalt mixture and the coating amount of adhesive layer required for forming composite beam specimens; Step 3: Forming and curing of composite beam specimens; Step 4: Fatigue performance test of the well-cured composite beam specimen; Step 5: Analysis and comparative evaluation of test data. 2. a kind of road surface bonding effect evaluation method based on composite beam fatigue test as claimed in claim 1, is characterized in that: in step 1, asphalt mixture is divided into the used asphalt mixture of upper layer and the used of lower layer of asphalt mixture. 3. A method for evaluating the bonding effect between pavement layers based on composite beam fatigue test as claimed in claim 1, characterized in that: in step 2, the asphalt mixture quality is calculated according to the required volume and measured density. 4. A method for evaluating the bonding effect between pavement layers based on composite beam fatigue test as claimed in claim 1, characterized in that: the forming and health-preserving method in step 3 specifically comprises the following steps; (1) Forming beam specimens are made by using test molds; (2) Cut the formed beam specimens into fatigue specimens, and the sticky layer is in the middle of the fatigue specimens; (3) Put the fatigue specimens into the environmental chamber for health preservation. 5. A method for evaluating the bonding effect between layers of pavement based on composite beam fatigue test as claimed in claim 4, characterized in that: step (1) the formed beam test piece includes an upper layer and a lower layer, and the upper layer and the lower layer There is an adhesive layer between them. 6. A method for evaluating the bond effect between layers of pavement based on composite beam fatigue test according to claim 4, characterized in that: step (1) the inner wall of the test mold has a dimension of 150mm×150mm×550mm. 7. A method for evaluating the bonding effect between layers of pavement based on composite beam fatigue test as claimed in claim 4, characterized in that: the specific method for making the formed beam specimen by the test mold in step (1) is as follows: (A) First brush the inside of the test mold with oil, and put the lower pressure block on the lower part of the test mold, exposing a part, then brush the backing plate with oil and put it on the lower pressure plate; (B) Fill the lower layer into the test mold with asphalt mixture several times, then spread the sticky layer of asphalt, fill the upper layer with asphalt mixture into the test mold several times, and finally put the upper compact into the test mold Inner, exposed part; (C) Put the entire test mold on the press, pressurize until the outer surfaces of the upper and lower pressure blocks are pressed into the test mold, and maintain the pressure for 5 minutes; (D) Remove the test mold after releasing the pressure, let it cool to room temperature, and then demould. 8. A method for evaluating the bond effect between layers of pavement based on composite beam fatigue test as claimed in claim 4, characterized in that: in step (2), the formed beam specimen is cut into 380mm×50mm× For a 63.5mm fatigue specimen, the sticky layer is at the middle of the height of the fatigue specimen. 9. A method for evaluating the bond effect between pavement layers based on composite beam fatigue test as claimed in claim 4, characterized in that: in step (3), the curing temperature is 15°C±0.5°C, and the curing time is more than 4h . 10. a kind of method for evaluating the bonding effect between layers of pavement based on composite beam fatigue test as claimed in claim 1, is characterized in that: step 4: the specific method of fatigue performance test is: put the composite beam specimen well maintained Into the four-point bending fatigue loading device, the loading frequency is 10Hz±0.1Hz, and the fatigue test is carried out in the continuous partial sinusoidal loading mode controlled by constant strain; the test termination condition is that the bending stiffness modulus is reduced to 50% of the initial bending stiffness modulus The corresponding number of loading cycles.