CN-121994600-A - Asphalt cement crack resistance evaluation method based on asphalt-aggregate constraint simulation

CN121994600ACN 121994600 ACN121994600 ACN 121994600ACN-121994600-A

Abstract

The invention relates to the technical field of road engineering asphalt pavement material performance detection, in particular to an asphalt cement crack resistance evaluation method based on asphalt-aggregate constraint simulation, which comprises the steps of preparing a cylindrical asphalt test piece which is completely bonded with round bonding surfaces of a top die and a bottom die; placing a test piece at a preset temperature, keeping the temperature constant until the temperature is uniform and stable, mounting the test piece on a tensile testing machine after heat preservation, carrying out uniaxial tension on the test piece in a preset loading mode until the test piece is completely broken under a constant temperature environment consistent with S2, continuously collecting real-time load and displacement in the whole process, calculating an anti-cracking index based on the collected load and displacement, evaluating the anti-cracking performance of asphalt cement, constructing a rigid constraint interface through a standardized test piece preparation process, and repeating the multidimensional constraint stress state and the real cracking mechanism of asphalt among aggregates in the uniaxial tension process, so as to construct a whole process standardized system from test piece preparation and constant temperature loading to data evaluation.

Inventors

CAO RONGJI
LV ZHENGLONG
PAN BIN
WEI WUJU
HAN CHAO
YUAN MENG
XU JINYU
CHENG ZHENGWEI

Assignees

苏交科集团检测认证有限公司
苏交科集团股份有限公司

Dates

Publication Date: 20260508
Application Date: 20260324

Claims (10)

1. An asphalt cement crack resistance evaluation method based on asphalt-aggregate constraint simulation is characterized by comprising the following steps: S1, preparing a cylindrical asphalt test piece which is completely bonded with the round bonding surfaces of the top die and the bottom die; s2, placing the test piece at a preset temperature, and preserving the temperature at a constant temperature until the temperature is uniform and stable; S3, mounting the test piece after heat preservation on a tensile testing machine, and carrying out uniaxial tension on the test piece in a preset loading mode under a constant temperature environment consistent with the S2 until the test piece is completely broken, and continuously collecting real-time load and displacement in the whole stretching process; S4, calculating an anti-cracking index based on the collected load and displacement, and evaluating the anti-cracking performance of the asphalt cement.
2. The asphalt cement crack resistance evaluation method based on asphalt-aggregate constraint simulation according to claim 1, wherein the test piece preparation method comprises: S11, cleaning bonding surfaces of a top die and a bottom die, and placing the top die, the bottom die and the spacing nails in an oven at 157-163 ℃ for preheating; S12, heating the asphalt cement to be tested to be in a flowing state, pouring the asphalt cement into a silica gel mold, and cooling; s13, placing the cooled asphalt cement into a preheated bottom die, and placing the bottom die back into an S11 oven for heating until the asphalt cement is completely melted and the whole bonding surface of the bottom die is paved; S14, taking the center of the bonding surface of the bottom die as the center of a circle, uniformly and transversely placing preheated interval nails according to an equilateral triangle at the middle position of the top surface of the bottom die, and then placing the bottom die back into an S11 oven for heating; and S15, horizontally placing the test piece after mold closing and locking in an S11 oven for heating, taking out, and cooling to complete shaping to obtain the test piece.
3. The asphalt cement crack resistance evaluation method based on asphalt-aggregate constraint simulation according to claim 2, wherein the cleaning method in S11 is to wipe the bonding surface with alcohol.
4. The asphalt cement crack resistance evaluation method based on asphalt-aggregate constraint simulation according to claim 2, wherein the asphalt cement to be tested in S12 is put into a container with a cover and heated.
5. The asphalt cement crack resistance evaluation method based on asphalt-aggregate constraint simulation according to claim 2, wherein the preset temperature in S2 is 24.5-25.5 ℃.
6. The asphalt cement crack resistance evaluation method based on asphalt-aggregate constraint simulation according to claim 1, wherein the preset loading mode in the step S3 is a graded loading mode, specifically, axial tension is applied in a displacement control mode of 0.8-1.2 mm/min, and after the tension reaches 40N, the load control mode is switched to 1.8-2.2N/S, and the uniform-speed stretching is continued until the test piece is completely broken.
7. The asphalt cement cracking performance evaluation method based on asphalt-aggregate constraint simulation according to claim 2, wherein the cracking index at least comprises tensile strength, post-peak elongation and strain energy index, and the calculation formula of the tensile strength is: ; Wherein, the Is tensile strength; D is the diameter of the bonding surface; the calculation formula of the post-peak elongation is as follows: ; Wherein, the The post-peak elongation is delta, and the post-peak elongation deformation value is delta, namely the displacement of the sample when the sample is attenuated to 80% of the tensile strength after reaching the tensile strength; The bonding thickness is the same as the diameter of the spacing nail; The strain energy index calculation formula is as follows: ; Wherein, the Is a strain energy index; And The unit variation of the elongation of the test piece along the abscissa direction is shown; the average action intensity corresponding to the unit elongation change quantity; the tensile strength of the i-th measurement point.
8. The method for evaluating crack resistance of asphalt cement based on asphalt-aggregate constraint simulation according to claim 7, wherein when the asphalt cement is modified asphalt, the qualification requirement is a strain energy index SEI not less than 5.0, and when the asphalt cement is recycled asphalt, the qualification requirement is a strain energy index SEI not less than 5.5.
9. The method for evaluating the cracking resistance of asphalt cement based on asphalt-aggregate constraint simulation according to claim 1, wherein the method for acquiring data in S3 is to record the displacement of the test piece and the corresponding load during the test at a speed of at least 2 points per second.
10. The asphalt cement crack resistance evaluation method based on asphalt-aggregate constraint simulation according to claim 2, wherein the test piece is mounted on a tensile testing machine, comprising the steps of fixing the bottom die on a bottom plate of the tensile testing machine, assembling a fish-eye joint on a top die, slowly pressing down after a Y-shaped joint is mounted on a main shaft of the testing machine, connecting the two joints through pins, and then removing a positioning rod.

Description

Asphalt cement crack resistance evaluation method based on asphalt-aggregate constraint simulation Technical Field The invention relates to the technical field of road engineering asphalt pavement material performance detection, in particular to an asphalt cement crack resistance evaluation method based on asphalt-aggregate constraint simulation. Background In the field of road engineering, low-temperature cracking and fatigue cracking of asphalt pavement are the most common early disease types of high-grade roads in China, and the cracking resistance of asphalt cement directly determines the service life and long-term durability of the asphalt pavement. Currently, the evaluation of the cracking resistance of asphalt cement mainly depends on a test method based on a linear viscoelasticity theory, such as a Dynamic Shear Rheology (DSR) test and a Bending Beam Rheology (BBR) test in a United states Supermave system, and the method can effectively represent the high-temperature rutting resistance and low-temperature cracking resistance basic rheological characteristics of asphalt and is widely applied to the field of global road engineering. However, in long-term engineering practice and academic research, there are core defects that cannot be overcome: Firstly, the existing rheology test method cannot simulate the multidimensional constraint stress state and stress concentration effect formed by wrapping the asphalt cement in the actual asphalt mixture by rigid aggregates, and the test conditions have essential differences from the actual service state of the asphalt pavement, so that the nonlinear failure behavior of materials with obvious nonlinear characteristics such as modified asphalt, reclaimed asphalt and the like under the complex stress state cannot be truly reflected; Secondly, the existing fatigue cracking and low-temperature cracking tests mostly take rheological indexes as evaluation cores, actual cracking of an asphalt test piece is not caused in the test process, the actual cracking is completely inconsistent with the real cracking form and the cracking evolution process of a pavement, and the anti-cracking capability of the asphalt cement under the constraint condition is difficult to accurately quantify; thirdly, the existing method is large in discreteness, poor in repeatability and poor in reproducibility of test results of modified asphalt and recycled asphalt, cannot provide reliable technical basis for research and development, screening and approach quality control of high-durability pavement asphalt materials, and severely restricts development of long-life asphalt pavement technologies. The traditional uniaxial tensile test can realize tensile fracture of an asphalt test piece, but a dumbbell-shaped free test piece is mostly adopted, the test piece can shrink laterally without limitation in the tensile process, the test piece is in a pure uniaxial stress state and completely does not accord with the constraint stress state of asphalt in a mixture, the correlation between a test result and the actual cracking performance of a road surface is extremely low, and the tensile test with the sidewall limit can introduce additional interference factors due to the sidewall friction resistance, so that test data is distorted, and the cracking performance of asphalt cannot be accurately represented. The information disclosed in this background section is only for enhancement of understanding of the general background of the disclosure and is not to be taken as an admission or any form of suggestion that this information forms the prior art that is well known to a person skilled in the art. Disclosure of Invention The invention provides an asphalt cement crack resistance evaluation method based on asphalt-aggregate constraint simulation, which comprises the steps of constructing a rigid constraint interface through a standardized test piece preparation process, reproducing a multidimensional constraint stress state and a real cracking mechanism of asphalt among aggregates in a uniaxial stretching process, constructing a whole-flow standardized system from test piece preparation and constant-temperature loading to data evaluation, and solving the problems of distortion of the stress state, inconsistent evaluation logic and poor result stability in the traditional method, thereby realizing accurate evaluation of the nonlinear crack resistance of the asphalt cement. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: An asphalt cement crack resistance evaluation method based on asphalt-aggregate constraint simulation comprises the following steps: S1, preparing a cylindrical asphalt test piece which is completely bonded with the round bonding surfaces of the top die and the bottom die; S2, placing the test piece at a preset temperature, and preserving the temperature at a constant temperature until the temperature is uniform and stable; S3, mounting t