CN107817214A - A kind of basalt fibre and asphalt mastic interface binding intensity measure device and method of testing - Google Patents

Abstract

The invention provides a device and a test method for measuring the interface bond strength between basalt fiber and asphalt mortar. The pull test measuring device includes an outer frame, a test mold, a pull test machine, a pull sensor, a displacement sensor, a temperature control system and a data acquisition system. The testing method of the present invention is as follows: preparing a basalt fiber asphalt mortar test piece, and cutting off the exposed fiber at the non-stretching end. The specimen was fixed, and the height of the clamped basalt fiber was adjusted. During the test, the vertical load was applied under a fixed temperature condition, so that the basalt fiber moved downward at a constant rate. The tensile force change and the displacement change of the corresponding displacement sensor are collected, and the interface shear strength between the basalt fiber and the asphalt mortar medium is calculated according to the statistical data of the pulling test. The device is reasonable in structure, easy to operate, and the measurement results are reasonable and reliable, which helps to reveal the action mechanism of the basalt fiber reinforced asphalt binder from the perspective of materials science.

Description

Device and test for interfacial bonding strength between basalt fiber and asphalt mortar method

technical field

The invention relates to the technical field of measuring the interfacial bonding strength of road engineering materials, in particular to a pullout test measuring device and a testing method for the interfacial bonding strength between basalt fibers and asphalt mortar media.

Background technique

In recent years, basalt fiber has been used in modified asphalt and asphalt mixture due to its excellent performance. The proportion of basalt fiber modified asphalt in the mixture system is very small, but it plays a very important role. The bonding between basalt fiber and asphalt The characteristics directly affect whether the asphalt mixture system can become a complete whole, but due to the limitation of test conditions, there are relatively few studies on basalt fiber modified asphalt at home and abroad.

At present, most of the studies are about the pull-out characteristics of steel fibers in the matrix in cement concrete, or the tensile test for a single fiber, or the qualitative evaluation of asphalt adhesion performance by water immersion method, etc., but these Neither method is suitable for quantitatively testing the adhesion between basalt fiber and asphalt mortar.

Contents of the invention

The purpose of the present invention is mainly to provide a pull-out test measuring device and a testing method for the interfacial bonding strength of basalt fiber and asphalt mortar in view of the deficiencies of existing road material interface bonding strength measuring devices. The structure design of the device is reasonable, the operation is simple, and the measurement results are reasonable and reliable, which is helpful to reveal the action mechanism of the basalt fiber reinforced asphalt binder from the perspective of materials science.

The purpose of the present invention is achieved through the following technical solutions:

A pull-out test measuring device for the interface bond strength between basalt fiber and asphalt mortar, including an outer frame, a test mold, a pull-out test machine, a pull sensor (with an accuracy of 0.001N and a range of 200N), a displacement sensor (with an accuracy of 0.01mm, measuring range is 100mm), temperature control system and data acquisition system; the outer frame is composed of a base, a plexiglass cover plate and two side beams, and rubber pads are arranged on the top of the two side beams; the upper part of the pull-out testing machine There are 4 fixed piles in the middle of the beam, and a vertical hole is left in the middle of the upper beam; the basalt fiber asphalt mortar specimen is prepared by the test mold, fixed in the middle of the upper beam through the fixed pile, and the free section of basalt fiber at one end of the sample passes through The small hole in the upper beam; the temperature control system inside the base is used to adjust the test environment temperature in the device; the pull-out test machine is placed on the sliding support of the outer frame base, and the basalt fiber is moved downward through the clamp; the pull-out test machine The tension change and the corresponding displacement change are input into the data acquisition system through the tension sensor and the displacement sensor.

Preferably, the trial mold is composed of two side molds and two end molds, wherein the two end molds respectively leave through holes in the middle; in order to ensure that the basalt fiber is not broken, the internal size of the trial mold is 15mm×15mm×25mm of prisms.

Preferably, the pull-out testing machine is placed on the sliding support of the base of the outer frame. When the power is turned on, the sliding support drives the pulling-out testing machine, and the basalt fiber is clamped by the clamp to move down along the metal slide bar; The displacement gauge fixedly connected to the pull-out testing machine moves down the pole.

Preferably, the tension sensor and the displacement sensor are connected to the pull-out testing machine and the sliding support, and the tension and displacement on the basalt fiber are transmitted to the data acquisition system through the transmission line; the precision of the tension sensor is 0.001N, and the measuring range is 200N ; The precision of the displacement sensor is 0.01mm, and the range is 100mm.

Preferably, a fixing bolt (10) is provided for fixing the upper beam (7) and the two side beams (12)

The test method of the pull-out test measuring device for measuring the interfacial bond strength of basalt fiber and asphalt mortar comprises the following steps:

Prepare asphalt mortar according to the content requirements of filler and asphalt in the asphalt mixture, and fully stir it evenly;

First pour half of the asphalt mortar into the test mold, then pass a bunch of basalt fibers through the small pores on both sides of the end mold, place it horizontally on the upper surface of the asphalt mortar sample, and apply a small tension at both ends of the fiber Straighten the fibers; then pour the other half of the asphalt mortar into the test mold, let the sample stand, cool to room temperature, scrape off the protruding asphalt mortar on the surface, cover the other side mold, and cut off the edge of the test sample Basalt fibers at the non-stretch end;

Place the piece to be tested in the fixed pile and fix it in the middle of the upper beam of the pull-out testing machine, and pass the free section of basalt fiber at one end of the sample through the small hole of the upper beam;

Connect the computer, adjust the height of the fixture through the control panel, so that the clearance between the top of the fixture and the bottom of the sample is 20mm, and then connect the free section of basalt fiber at the lower end of the sample to the fixture;

Cover the plexiglass cover, turn on the temperature controller, and wait until the test temperature is reached in the device;

Turn on the power to start the testing machine, so that the fixture connected to the basalt fiber moves downward at a constant rate of 0.5mm/min with the pull-out testing machine, and applies tension to the basalt fiber;

Stop the test until the basalt fiber is completely pulled out;

Read the tensile force output by the data acquisition system and the corresponding displacement data change value;

The interface bond strength between basalt fiber and asphalt mortar medium is calculated according to formula (1), and the interface residual bond strength between basalt fiber and asphalt mortar medium is calculated according to formula (2), and the calculation is accurate to 1.0×10 ^{- 3} :

In the formula: τm _{—interfacial} bond strength between basalt fiber and asphalt mortar medium, MPa;

τ _n —Interfacial residual bond strength between basalt fiber and asphalt mortar medium, MPa;

N _max — is the maximum tensile force borne by the fiber in the pull-out test, N;

N _a —the tensile force on the basalt fiber when it tends to be stable before the end of the test, N;

S—the contact area between basalt fiber and asphalt mortar medium, that is, the shear area, calculated according to the fiber diameter and the thickness of the asphalt sample, mm ² .

Repeat the above operation 3 times, calculate the average value of the data as the final result.

Compared with the prior art, the present invention has the following significant advantages:

(1) The present invention adopts the drawing test of basalt fiber and asphalt mortar to be convenient to quantitatively analyze the interface force attenuation rule of basalt fiber and asphalt mortar, explore the mechanical performance in the bond failure process between basalt fiber and asphalt matrix, This makes the test results more objective and reasonable.

(2) In the process of testing with this method, different basalt fiber embedding depths and different types of basalt fiber forming samples can be used to study the influence of fiber length and fiber mechanical properties on the interface bond strength.

(3) The present invention also provides a pull-out test measuring device for the interfacial bond strength of basalt fiber and asphalt mortar. The action mechanism of basalt fiber reinforced asphalt binder is revealed from the perspective of materials science.

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Description of drawings

Fig. 1 is a kind of drawing test measuring device structural representation that is used for basalt fiber and asphalt mortar interface bond strength of the present invention;

Fig. 2 is a structural schematic diagram of the test mold of the present invention.

The reference signs and the components they represent are: 1-test mold, 2-end mold, 3-end mold hole, 4-side mold, 5-plexiglass cover plate, 6-test piece, 7-upper beam, 8-fixed pile, 9-round hole of upper beam, 10-fixed bolt, 11-basalt fiber, 12-outer frame side beam, 13-outer frame base, 14-sliding support, 15-pull-out testing machine, 16- Fixture, 17-tension sensor, 18-displacement gauge, 19-benchmark, 20-displacement sensor, 21-metal slider, 22-transmission line, 23-data acquisition system, 24-output interface, 25-switch, 26-temperature control Device, 27-rubber spacer.

Detailed ways

In order to clarify the technical scheme and technical purpose of the present invention, the present invention will be further introduced below in conjunction with the accompanying drawings and specific implementation methods.

As shown in Figures 1 and 2, a pull-out test measuring device for the interface bond strength between basalt fiber and asphalt mortar includes an outer frame, a test mold 1, a pull-out testing machine 15, a tension sensor 17, and a displacement sensor 20 , temperature control system 26 and data acquisition system 23. The outer frame is composed of a base 13, a plexiglass cover plate 5 and two side beams 12, wherein the top of the side beams 12 is provided with a rubber pad 27; the middle of the upper beam 7 is provided with four fixed piles 8, and the middle of the upper beam 7 Leave a vertical circular hole 9 with a diameter of about 5mm.

The pull-out testing machine 15 is placed above the sensor, the tension sensor (with an accuracy of 0.001N, and a range of 200N) 17, and the displacement sensor (with an accuracy of 0.01mm, and a range of 100mm) 20 are connected to the pull-out testing machine 15 and the sliding support 14. When the power supply 25 is turned on, the sliding support 14 drives the pull-out testing machine 15, and the basalt fiber 11 is clamped by the clamp 16 and moves downward along the metal slide bar 21. Simultaneously, the displacement meter 18 fixedly connected with the pull-out testing machine 15 moves downward along the mark pole 19 . At the same time, the transmission line 22 transmits the changes of the tension and displacement on the basalt fiber 11 over time to the data acquisition system 23 .

The test mold 1 is composed of two side molds 4 and two end molds 2, in which the two end molds 2 respectively leave holes 3 in the center; in order to ensure that the basalt fibers are not broken, the internal dimensions of the test mold are 15mm×15mm× 25mm prism.

The pull-out test determination process of the interface bond strength between basalt fiber and asphalt mortar is as follows:

1. Prepare asphalt mortar according to the content requirements of filler and asphalt in the asphalt mixture. Generally, modified asphalt is used, and the temperature is 160 ° C, and it is fully stirred evenly;

2. First pour half of the asphalt mortar into the test mold 1, then pass a bundle of basalt fibers 11 about 75mm long through the small holes 3 on both sides of the test mold, and place it horizontally on the asphalt mortar sample On the surface, one end of the basalt fiber leaks about 30mm in length, and a slight tension is applied to both ends of the fiber to straighten the fiber;

3. Pour the other half of the asphalt mortar into the test mold, let the sample stand, cool to room temperature, scrape off the protruding sample with a hot scraper, cover the other side mold, and cut off the test sample 6 at the same time Basalt fibers at the non-stretch ends at the edges;

4. Place the test piece 6 vertically in the fixed pile 8 and fix it in the middle of the upper beam 7, and pass the free section basalt fiber 11 at one end of the sample through the small hole 9 of the upper beam;

5. Connect the computer, adjust the height of the fixture 16 through the control panel, so that the clearance height between the top of the fixture 16 and the bottom surface of the sample 6 is 20 mm, and then connect the free section basalt fiber 11 at the lower end of the sample 6 to the fixture 16;

6. Cover the plexiglass cover plate 5, turn on the temperature controller 26, and keep the temperature in the device constant;

7. Turn on the power supply 25 and start the testing machine, so that the clamp 16 connected to the basalt fiber 11 moves downward with the pull-out testing machine 15 at a constant rate of 0.5mm/min, and applies a pulling force to the basalt fiber 11;

8. Stop the test until the basalt fiber 11 is completely pulled out;

9. Read the pulling force output by the data acquisition system 23 and the corresponding displacement data change value;

10. The interface bond strength between basalt fiber and asphalt mortar medium is calculated according to formula (1), and the interface residual bond strength between basalt fiber and asphalt mortar medium is calculated according to formula (2), and the calculation is accurate to 1.0× ^10-3 :

In the formula: τm _{—interfacial} bond strength between basalt fiber and asphalt mortar medium, MPa;

τ _n —Interfacial residual bond strength between basalt fiber and asphalt mortar medium, MPa;

N _max — is the maximum tensile force borne by the fiber in the pull-out test, N;

N _a —the tensile force on the basalt fiber when it tends to be stable before the end of the test, N;

S—the contact area between basalt fiber and asphalt mortar medium, that is, the shear area, calculated according to the fiber diameter and the thickness of the asphalt sample, mm ² .

11. Repeat the above operation 3 times, calculate the average value of the data as the final result.

Claims (9)

1. a basalt fiber and asphalt mortar interface bond strength measuring device, is characterized in that: comprise outer frame (5,12,13), test mold (1), pull-out testing machine (15), tension sensor (17 ), displacement sensor (20), temperature control system (26) and data acquisition system (23); described outer frame is made up of base (13), plexiglass cover plate (5) and two side beams (12); There are 4 fixed piles (8) in the middle of the upper beam (7), and a vertical circular hole (9) is left in the middle of the upper beam (7); it is used to prepare the test mold (1 ), fixed on the middle part of the upper beam (7) by a fixed pile (8), and ensured that the free section basalt fiber (11) at one end of the basalt fiber asphalt mortar specimen (6) passes through the vertical round hole (9) of the upper beam , the top of the test mold (1) is a machine glass cover plate (5); in addition, the pull-out testing machine (15) is placed on the sliding support (14) of the outer frame base (13), and is passed through the clamp (16) ) clamps the free section basalt fiber (11) and moves downward; the tensile force change and the corresponding displacement change of the pull-out testing machine (15) are input into the data acquisition system through the tensile force sensor (17) and the displacement sensor (20). In addition, the device A temperature control system (26) is provided to maintain a constant temperature in the device. 2. a kind of basalt fiber and asphalt mortar interface bond strength measuring device according to claim 1, is characterized in that: described trial mold (1) is made of two side molds (4), two end molds ( 2) composition, wherein the two end molds (2) respectively leave through holes (3) in the center; the internal size of the test mold is a prism of 15mm×15mm×25mm to ensure that the basalt fiber is not broken. 3. a kind of basalt fiber and asphalt mortar interface bond strength measuring device according to claim 1, is characterized in that: described pull-out testing machine (15) is placed in the sliding support of outer frame base (13) (14), when the power supply (25) is switched on, the sliding support (14) drives the pull-out testing machine (15), and the basalt fiber (11) is clamped by the clamp (16) to move down along the metal slide bar (21). 4. a kind of basalt fiber and asphalt mortar interface bonding strength measuring device according to claim 1, is characterized in that: described tension sensor (17), displacement sensor (20) connect pull-out testing machine (15) With the sliding support (14), the tension and displacement on the basalt fiber (11) are transmitted to the data acquisition system (23) through the transmission line (22) with time; the precision of the tension sensor (17) is 0.001N, and the range is 200N; the precision of the displacement sensor (20) is 0.01mm, and the measuring range is 100mm. 5. A device for measuring the interface bond strength between basalt fiber and asphalt mortar according to claim 1, characterized in that: the outer frame base (13) is provided with a temperature control system (26). 6. a kind of basalt fiber and asphalt mortar interface bond strength measuring device according to claim 1, is characterized in that: be provided with fixing bolt (10) and be used for fixing upper beam (7) and two side beams (12 ). 7. A test method of the basalt fiber and asphalt mortar interface bond strength measuring device according to claim 1-6, characterized in that: comprising the steps: (1) According to the content requirements of the filler and asphalt in the asphalt mixture, prepare fully stirred and uniform asphalt mortar; (2) Pour half of the asphalt mortar into the test mold (1), and at the same time, pass a bunch of basalt fibers (11) through the small pores (3) of the end molds on both sides of the test mold (1), and place them horizontally On the upper surface of the asphalt mortar sample, apply a small tensile force at both ends of the fiber to straighten the fiber; then pour the other half of the asphalt mortar into the test mold (1), let the sample stand, cool to room temperature, and scrape off the convex surface. Cover the other side form (4) with the asphalt mortar, and cut off the basalt fiber at the non-stretch end of the test piece (6) edge; (3) Place the test piece (6) vertically in the fixed pile (8) and fix it in the middle of the upper beam (7), and pass the free segment of basalt fiber (11) at one end of the sample through the small hole of the upper beam ( 9); (4) connect computer, adjust the height of fixture (16), make the headroom height of fixture (16) top and sample (6) bottom surface be 20mm, then the free section basalt fiber (11) of sample (6) lower end and Fixtures (16) are connected; (5) cover the plexiglass cover plate (5), open the temperature controller (26), to the constant temperature in the device; (6) switch on the power supply (25) and start the testing machine, so that the clamp (16) connected to the basalt fiber (11) moves downward with a constant rate of 0.5mm/min with the pull-out testing machine (15), and the basalt fiber (11) ) exerts a pulling force; (7) Stop the test until the basalt fiber (11) is completely pulled out; (8) read the pulling force output by the data acquisition system (23) and the corresponding displacement data change value; (9) Calculate the interface bond strength between basalt fiber and asphalt mortar medium and the interface residual bond strength between basalt fiber and asphalt mortar medium. 8. the test method of basalt fiber and asphalt mortar interface bond strength measuring device according to claim 7, is characterized in that: the interface bond strength between described basalt fiber and asphalt mortar medium is according to formula (1 )get: In the formula: τm _{—interfacial} bond strength between basalt fiber and asphalt mortar medium, MPa; N _max — is the maximum tensile force borne by the fiber in the pull-out test, N; S—the contact area between basalt fiber and asphalt mortar medium, that is, the shear area, calculated according to the fiber diameter and the thickness of the asphalt sample, mm ² . 9. the test method of basalt fiber and asphalt mortar interface bond strength measuring device according to claim 7, is characterized in that: the interface residual bond strength between described asphalt mortar medium obtains according to formula (2) : τ _n —Interfacial residual bond strength between basalt fiber and asphalt mortar medium, MPa; N _a —the tensile force on the basalt fiber when it tends to be stable before the end of the test, N; S—the contact area between basalt fiber and asphalt mortar medium, that is, the shear area, calculated according to the fiber diameter and the thickness of the asphalt sample, mm ² .