Method for testing tension sensitivity of stress self-sensing cement-based material

A technology of cement-based materials and testing methods, which is applied in the directions of material resistance, testing material strength by applying stable tension/pressure, and preparation of samples for testing, etc. low problems, to achieve the effect of high stability, good compatibility and combination, and high accuracy

Pending Publication Date: 2021-04-23
BEIJING UNIV OF CIVIL ENG & ARCHITECTURE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] The purpose of the present invention is to provide a stress self-sensing cement-based material tensile performance test method to solve the above problems, overcome the existing stress self-sensing cement-based material in the tensile direction of the sensitive performance test method has low accuracy and stability Defects such as low compatibility, poor compatibility between electrode and substrate

Method used

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  • Method for testing tension sensitivity of stress self-sensing cement-based material
  • Method for testing tension sensitivity of stress self-sensing cement-based material
  • Method for testing tension sensitivity of stress self-sensing cement-based material

Examples

Experimental program
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Effect test

Embodiment 1

[0051] S1: if figure 1 , 2 As shown in , 3, prepare the cement paste and pour it into the "8" mold to ensure that the paste has good and almost uniform fluidity during the preparation of the test block 4. Insert four pieces of mesh metal electrodes into the cement slurry in a parallel arrangement, two first electrodes 1 on the inner side, and two second electrodes 2 on the outer side. After 28 days of curing, the structure of test block 4 is as follows figure 1 , 2 , 3 shown.

[0052] S2: Adjust the Keithley 2700 six and a half digit data acquisition multimeter test mode to two-electrode resistance test, connect two of the test lines to the two first electrodes 1 inside the test block 4, measure and record the distance between the two first electrodes 1 on the inside The resistance R 1 .

[0053] S3: Place the test block 4 in the fixture of the electronic universal testing machine, keep the upper and lower fixtures aligned and fix the test block 4 well, and perform an ax...

Embodiment 2

[0055] S1: The process of preparing the test block is as in Example 1.

[0056] S2: Adjust the Keithley 2700 6.5-digit data acquisition multimeter test mode to four-electrode resistance test. The four test lines are respectively connected to the inner and outer four electrodes according to the four-electrode resistance test method. Use the Keithley 2700 6.5-digit data acquisition multimeter to test the inner two electrodes The resistance R 1 .

[0057] S3: Place the test block in the fixture of the electronic universal testing machine, keep the upper and lower fixtures aligned and fix the test block well, and perform axial tensile test on the test block, apply a maximum tensile force of 300N, and the loading speed is 0.3mm / min, during the process of tension loading, the resistance R between two electrodes is collected in real time 2 , the calculation and evaluation process are the same as in Example 1.

Embodiment 3

[0059] S1: The process of preparing the test block is as in Example 1.

[0060] S2: Connect the two test wires equipped with the TH2810D LCR digital bridge to the two inner electrodes, and collect the initial resistance R 1 .

[0061] S3: Place the test block in the fixture of the electronic universal testing machine, keep the upper and lower fixtures aligned and fix the test block well, and perform axial tensile test on the test block, apply a maximum tensile force of 350N, and the loading speed is 0.35mm / min, during the process of tension loading, the resistance R between two electrodes is collected in real time 2 , the calculation and evaluation process are the same as in Example 1.

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Abstract

The invention provides a method for testing the tension sensitivity of a stress self-sensing cement-based material, and belongs to the field of cement material performance testing. The method comprises the following steps: pouring prepared composite cement paste into an 8-shaped mold, inserting at least two metal electrodes into the composite cement paste in a parallel arrangement mode, and after a test block is hardened, performing mold removal and maintenance; then testing the initial resistance R1 of the test block; carrying out an axis tensile test on the test block, collecting the resistance R2 between the electrodes in real time in the tension loading process, and calculating the real-time resistance change rate = (R2-R1)/R1; and finally, determining the relationship between the tensile force for judging the quality of the tension-sensitive property and the resistance change rate. The method has the advantages of high accuracy, simplicity, convenience and the like, and the data acquisition and processing of the resistance test have the advantages of simple and reliable circuit, digitization, high stability, low cost, real-time monitoring and the like.

Description

technical field [0001] The invention relates to the field of cement material performance testing, in particular to a stress self-sensing cement-based material tensile performance testing method. Background technique [0002] Since American professor D.D.L.Chung et al. mixed carbon fiber into cement-based composite materials and developed a new type of self-sensing cement material, many researchers have also followed up, combining carbon nanotubes, graphene, nano New carbon materials such as carbon black are added to cement-based materials to develop a stable, high-sensitivity, and high-durability stress self-sensing cement-based composite material. The resistivity of this cement-based composite material with conductive materials can change with the external The stress / strain change in the concrete structure is monitored by measuring the change in its electrical resistivity. Therefore, it has broad application prospects in crack monitoring of concrete structures, vehicle wei...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/08G01N1/36G01N27/04
Inventor 王琴詹达富
Owner BEIJING UNIV OF CIVIL ENG & ARCHITECTURE
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