CN108871937B - Test method for testing water stability of asphalt concrete - Google Patents
Test method for testing water stability of asphalt concrete Download PDFInfo
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- CN108871937B CN108871937B CN201810664990.7A CN201810664990A CN108871937B CN 108871937 B CN108871937 B CN 108871937B CN 201810664990 A CN201810664990 A CN 201810664990A CN 108871937 B CN108871937 B CN 108871937B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
- G01N3/04—Chucks
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0017—Tensile
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/006—Crack, flaws, fracture or rupture
- G01N2203/0067—Fracture or rupture
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
- G01N2203/0075—Strain-stress relations or elastic constants
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/04—Chucks, fixtures, jaws, holders or anvils
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Abstract
The invention discloses a test method for testing the water stability of asphalt concrete, which comprises the following steps: 1) manufacturing an asphalt concrete sample, and dividing the asphalt concrete sample into a test group and a comparison group, wherein the test group is subjected to freeze-thawing treatment, and the comparison group is not subjected to freeze-thawing treatment; 2) fixing the asphalt concrete sample between loading clamps, and applying a loading speed with a set value to the sample; 3) monitoring the change of load and displacement, and making a force-displacement curve chart; 4) and (4) calculating indirect stretching energy according to the force and displacement curve graph, and calculating the stretching residual energy ratio between freeze thawing to represent the water stability of the asphalt concrete. Compared with the traditional test method, the test method for testing the water stability of the asphalt concrete can better represent the water stability of the asphalt concrete by using data obtained by measurement of the test method, so that the test result is more accurate.
Description
Technical Field
The invention relates to the technical field of asphalt concrete quality detection, in particular to a test method for testing the water stability of asphalt concrete.
Background
In the prior art, a sample piece is pressurized in the process of testing the water stability of the asphalt concrete, the pressure intensity and the pressure of the sample piece are monitored in the pressurizing process, the maximum pressure intensity and the maximum pressure intensity which can be borne by the sample piece are detected, and the water stability of the asphalt concrete is evaluated, but the testing result is easily influenced by sample difference and other condition difference; particularly, the stress concentration of the clamp on the asphalt concrete sample is easy to influence the maximum load; thereby affecting the test result; therefore, the accuracy is not high; in the prior art, a relatively accurate asphalt concrete stability evaluation method is lacked, and the water stability of asphalt concrete can be more accurately and comprehensively measured.
Disclosure of Invention
In view of the above-mentioned defects in the prior art, the technical problem to be solved by the present invention is to provide a more accurate method for evaluating the stability of asphalt concrete, which can more accurately and comprehensively measure the water stability of asphalt concrete.
In order to achieve the aim, the invention provides a test method for testing the water stability of asphalt concrete, which comprises the following steps:
1) manufacturing an asphalt concrete sample, and dividing the asphalt concrete sample into a test group and a comparison group, wherein the test group is subjected to freeze-thawing treatment, and the comparison group is not subjected to freeze-thawing treatment;
2) fixing the asphalt concrete sample between loading clamps, and applying a loading speed with a set value to the sample;
3) monitoring the change of load and displacement, and making a force-displacement curve chart;
4) and calculating indirect stretching energy according to the force and displacement curve graph, and calculating the freeze-thaw indirect stretching residual energy ratio to represent the water stability of the asphalt concrete.
Preferably, in the step 1), the asphalt concrete sample is prepared according to the following steps:
11) molding a standard Marshall test piece, compacting two sides of the standard Marshall test piece for a plurality of times respectively by using a Marshall compaction instrument to obtain a test piece to be frozen and thawed and a test piece of a comparison group;
12) carrying out vacuum water saturation on the test piece to be frozen and thawed in the step 11);
13) freezing the vacuum saturated test piece to be frozen and thawed;
14) preserving the temperature of the frozen test piece to be frozen and thawed in a constant temperature water tank at 60 +/-0.5 ℃;
15) soaking the test pieces to be frozen and thawed and the test pieces of the comparison group subjected to constant temperature heat preservation in the step 14) into a constant temperature water tank with the temperature of 25 +/-0.5 ℃, keeping the soaking time for not less than 2 hours, and taking out the test pieces to be frozen and thawed for later use after soaking.
Preferably, in the step 2), the loading fixture comprises an upper loading plate (1) and a lower loading plate (2), the upper loading plate (1) is horizontally arranged, and the lower loading plate (2) is parallel to the upper loading plate (1); the width (L1) of the upper loading plate (1) and the width (L2) of the lower loading plate (2) are not less than the maximum width (D) of the sample piece.
Preferably, in the step 2), a force is applied to the upper loading plate (1) or the lower loading plate (2) to apply a set acceleration to the test piece.
Preferably, in the step 3), an electronic universal testing machine is used for monitoring the change of the load and the displacement of the test piece.
Preferably, in the step 4), the indirect stretching energy is obtained according to the following steps:
41) respectively printing the displacement and force diagram lines of the freeze-thaw test group and the displacement and force diagram lines of the comparison group;
42) finding a test piece cracking point (B) of the freeze-thaw test group on the displacement and force diagram line of the freeze-thaw test group, and setting a graph original point (A) and a projection point (C) of the cracking point (B) on the displacement axis;
43) at the moment, the ABC is cut off by scissors, and the mass m is weighed1Then, the recording paper mass m of unit area is weighed by the recording paper with known area0And obtaining the area of the curve shape (ABC) according to the formula (1):
wherein S isΩABCThe area of curve ABC, namely the indirect stretching energy, is expressed by the unit of N.m;
m0the unit area is the mass of the recording paper, and the unit is g/(N-m)]；
m1The recording paper mass of ABC part is g;
44) the curves of the comparison set are likewise processed according to the steps 42) to 43).
Preferably, in the step 4), the freeze-thaw indirect stretching residual energy ratio is calculated according to the following formula:
wherein: ER is the ratio (%) of residual energy of freeze-thaw indirect stretching;
The invention has the beneficial effects that: compared with the traditional test method, the test method for testing the water stability of the asphalt concrete can better represent the water stability of the asphalt concrete by using the data obtained by the test method, so that the test result is more accurate. Meanwhile, in the method, a new test fixture is utilized, the fixture is utilized to complete the test, the fracture process of the test piece can be closer to the actual application process, the accuracy of the test is further improved, and the strength and the deformation resistance of the asphalt concrete can be more accurately reflected by using the freeze-thaw indirect tensile residual energy ratio in the test.
Drawings
FIG. 1 is a flow chart of a method according to an embodiment of the present invention.
Fig. 2 is a schematic view of the structure of the clamp of the present invention.
Fig. 3 is a graph of indirect stretching energy obtained in an embodiment of the present invention.
Detailed Description
The invention is further illustrated by the following examples in conjunction with the accompanying drawings:
as shown in FIG. 1, a test method for testing the water stability of asphalt concrete comprises the following steps:
1) manufacturing an asphalt concrete sample, and dividing the asphalt concrete sample into a test group and a comparison group, wherein the test group is subjected to freeze-thawing treatment, and the comparison group is not subjected to freeze-thawing treatment;
2) fixing the asphalt concrete sample between loading clamps, and applying a loading speed with a set value to the sample;
3) monitoring the change of load and displacement, and making a force-displacement curve chart;
4) and calculating indirect stretching energy according to the force and displacement curve graph, and calculating the freeze-thaw indirect stretching residual energy ratio to represent the water stability of the asphalt concrete.
Further, in the step 1), an asphalt concrete sample is prepared according to the following steps:
11) molding a standard Marshall test piece, compacting two sides of the standard Marshall test piece for a plurality of times respectively by using a Marshall compaction instrument to obtain a test piece to be frozen and thawed and a test piece of a comparison group;
12) carrying out vacuum water saturation on the test piece to be frozen and thawed in the step 11);
13) freezing the vacuum saturated test piece to be frozen and thawed;
14) preserving the temperature of the frozen test piece to be frozen and thawed in a constant temperature water tank at 60 +/-0.5 ℃;
15) soaking the test pieces to be frozen and thawed and the test pieces of the comparison group subjected to constant temperature heat preservation in the step 14) into a constant temperature water tank with the temperature of 25 +/-0.5 ℃, keeping the soaking time for not less than 2 hours, and taking out the test pieces to be frozen and thawed for later use after soaking.
In this embodiment, the method specifically includes the following steps:
the method comprises the steps of placing an asphalt concrete sample between two straight steel plates with the block size of 100mm multiplied by 10mm or 150mm multiplied by 10mm, carrying out pressure test on the asphalt concrete sample on an electronic universal testing machine at the speed of 50mm/min, and obtaining a force-displacement curve on an operation software interface of the electronic universal testing machine. And calculating the area enclosed by the indirect stretching energy-force and displacement curve according to the force-displacement curve. And (4) dividing the indirect stretching energy between the freeze-thaw groups by the indirect stretching energy between the non-freeze-thaw groups to obtain the freeze-thaw indirect stretching residual energy ratio, and representing the water stability of the asphalt concrete.
When the test piece is processed, the processing is specifically carried out according to the following steps:
(1) and (3) molding the standard Marshall test pieces, and compacting the two surfaces of each test piece 50 times by using a Marshall compaction device, wherein the number of the samples is not less than 6.
(2) Randomly dividing the samples into two groups, wherein each group of samples is not less than 3, respectively testing the void ratio, and the difference between the maximum value and the minimum value of the void ratio is not more than +/-0.5%. One group is a standard group and is stored at room temperature for standby without any treatment; the other group is taken as a condition group for freeze thawing treatment;
(3) carrying out vacuum water saturation on a second group of test pieces, namely placing the test pieces in a normal-temperature water tank, soaking the test pieces in water, then placing the water tank containing the test pieces in a vacuum drying box, starting a vacuum pump connected with the vacuum drying box, keeping the vacuum drying box at a vacuum degree of 97.3-98.7 kPa for 15min, then opening a valve to recover the normal pressure, and placing the test pieces in the water for 30 min;
(4) taking out five test pieces of each group saturated with water in vacuum, placing the test pieces in a plastic bag, adding about 10mL of water, tightening a bag opening, placing the test pieces in a constant-temperature refrigerator, and keeping the frozen temperature at minus 18 +/-2 ℃ for 16 +/-1 h;
(5) taking out the frozen test piece, immediately putting the test piece into a constant-temperature water tank with the constant temperature of 60 +/-0.5 ℃, removing the plastic bag, and preserving the heat for 24 hours;
(6) the heat-preserved test piece and the test piece preserved at normal temperature are completely immersed into a constant-temperature water tank at the temperature of 25 +/-0.5 ℃ for not less than 2 hours, and the distance between every two test pieces is not less than 10 mm;
(7) and taking out the test piece to measure the height of each test piece, and immediately carrying out an indirect Brazilian wheel disc tensile test by using an electronic universal testing machine at a loading rate of 50 mm/min.
As shown in fig. 2. Further, in the step 2), the loading fixture comprises an upper loading plate 1 and a lower loading plate 2, the upper loading plate 1 is horizontally arranged, and the lower loading plate 2 is parallel to the upper loading plate 1; the width L1 of the upper loading plate 1 and the width L2 of the lower loading plate 2 are not less than the maximum width D of the sample 3.
Further, in the step 2), a force is applied to the upper loading plate (1) or the lower loading plate (2) to apply a set acceleration to the test piece.
Further, in the step 3), an electronic universal testing machine is used for monitoring the change of the load and the displacement of the test piece.
As shown in fig. 3, a graph of displacement versus applied force is obtained, wherein the horizontal axis represents deformation displacement of the sample piece in mm; the vertical axis is the acting force applied by the electronic testing machine, and the unit is N; after obtaining the graph, in the step 4), the indirect stretching energy is obtained according to the following steps:
41) respectively printing the displacement and force diagram lines of the freeze-thaw test group and the displacement and force diagram lines of the comparison group;
42) finding a test piece cracking point B of the freeze-thaw test group on the displacement and force diagram line of the freeze-thaw test group, and setting a graph original point A and a projection point C of the cracking point B on the displacement axis;
43) at the moment, the ABC is cut off by scissors, and the mass m is weighed1Then, the recording paper mass m of unit area is weighed by the recording paper with known area0And obtaining the area of the curve shape (ABC) according to the formula (1):
wherein S isΩABCThe area of curve ABC, namely the indirect stretching energy, is expressed by the unit of N.m;
m0the unit area is the mass of the recording paper, and the unit is g/(N-m)]；
m1The recording paper mass of ABC part is g;
44) the curves of the comparison set are likewise processed according to the steps 42) to 43).
Further, in the step 4), the freeze-thaw indirect stretching residual energy ratio is calculated according to the following formula:
wherein: ER is the ratio (%) of residual energy of freeze-thaw indirect stretching;
When the test is carried out, the number of effective test pieces in each group of test is not less than 3, and the average value is taken as the test result. When the difference between one test data and the average value in a group of test values is larger than k times of the standard deviation, the test value is discarded, and the average value of the rest test values is used as the test result. Such test results are more accurate.
Through tests, when the number m of the samples is 3, 4, 5 and 6, the k values are 1.15, 1.46, 1.67 and 1.82 respectively. In other embodiments, different K values may be obtained according to specific items of the sample to be tested, and the obtained data may be filtered to obtain more accurate test results.
The foregoing detailed description of the preferred embodiments of the invention has been presented. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning and limited experiments based on the prior art according to the concept of the present invention should be within the scope of protection defined by the claims.
Claims (5)
1. A test method for testing the water stability of asphalt concrete is characterized by comprising the following steps: the method comprises the following steps:
1) manufacturing an asphalt concrete sample, and dividing the asphalt concrete sample into a test group and a comparison group, wherein the test group is subjected to freeze-thawing treatment, and the comparison group is not subjected to freeze-thawing treatment;
2) fixing the asphalt concrete sample between loading clamps, and applying a set value of loading speed to the asphalt concrete sample;
3) monitoring the change of load and displacement, and making a force-displacement curve chart;
4) according to the force and displacement curve diagram, calculating indirect stretching energy, and calculating the freeze-thaw indirect stretching residual energy ratio to represent the water stability of the asphalt concrete,
in the step 4), indirect stretching energy is obtained according to the following steps:
41) printing the displacement and force diagram lines of the freeze-thaw test group and the displacement and force diagram lines of the comparison group respectively;
42) finding a test piece cracking point (B) of the freeze-thaw test group on a displacement and force diagram line of the freeze-thaw test group, and setting a graph original point (A) and a projection point (C) of the cracking point (B) on a displacement axis;
43) at the moment, the ABC is cut off by scissors, and the mass m is weighed1Then, the recording paper mass m of unit area is weighed by the recording paper with known area0And obtaining the area of the curve shape (ABC) according to the formula (1):
wherein S isΩABCThe area of curve ABC, namely the indirect stretching energy, is expressed by the unit of N.m;
m0the unit area is the recording paper mass, and the unit is g/(N.m);
m1the recording paper mass of ABC part is g;
44) processing the curves of the comparison group according to the steps 42) to 43);
in the step 4), the freeze-thaw indirect stretching residual energy ratio is calculated according to the following formula:
wherein: ER is the ratio (%) of residual energy of freeze-thaw indirect stretching;
2. The test method for testing the water stability of asphalt concrete according to claim 1, wherein: in the step 1), the asphalt concrete sample is prepared according to the following steps:
11) molding a standard Marshall test piece, compacting two sides of the standard Marshall test piece for a plurality of times respectively by using a Marshall compaction instrument to obtain a test piece to be frozen and thawed and a test piece of a comparison group;
12) carrying out vacuum water saturation on the test piece to be frozen and thawed in the step 11);
13) freezing the vacuum saturated test piece to be frozen and thawed;
14) preserving the temperature of the frozen test piece to be frozen and thawed in a constant temperature water tank at 60 +/-0.5 ℃;
15) soaking the test pieces to be frozen and thawed and the test pieces of the comparison group subjected to constant temperature heat preservation in the step 14) into a constant temperature water tank with the temperature of 25 +/-0.5 ℃, keeping the soaking time for not less than 2 hours, and taking out the test pieces to be frozen and thawed for later use after soaking.
3. The test method for testing the water stability of asphalt concrete according to claim 1, wherein: in the step 2), the loading fixture comprises an upper loading plate (1) and a lower loading plate (2), the upper loading plate (1) is horizontally arranged, and the lower loading plate (2) is parallel to the upper loading plate (1); the width (L1) of the upper loading plate (1) and the width (L2) of the lower loading plate (2) are not less than the maximum width (D) of the asphalt concrete sample.
4. The test method for testing the water stability of asphalt concrete according to claim 3, wherein: in the step 2), acting force is applied to the upper loading plate (1) or the lower loading plate (2) to apply a set loading speed to the asphalt concrete sample.
5. The test method for testing the water stability of asphalt concrete according to claim 1, wherein: and in the step 3), monitoring the changes of the load and the displacement of the asphalt concrete sample by using an electronic universal testing machine.
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