CN100487467C - Method for measuring volume resistance rate of conductive cement base material - Google Patents
Method for measuring volume resistance rate of conductive cement base material Download PDFInfo
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- CN100487467C CN100487467C CNB2006101172138A CN200610117213A CN100487467C CN 100487467 C CN100487467 C CN 100487467C CN B2006101172138 A CNB2006101172138 A CN B2006101172138A CN 200610117213 A CN200610117213 A CN 200610117213A CN 100487467 C CN100487467 C CN 100487467C
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Abstract
This invention relates to the civil engineering materials field, which is a method of testing volume resistivity of conductive cement-based materials. The method tests sample voltammetric with four electrodes based on principle of resistance first, and calculate the resistivity values of the sample based on the formula. With the following steps: 1) select the cement-based material samples, and take the pretreatments; 2) take two ends of the testing sample as current access electrode, and two middle parallel surfaces of the sample as voltage test electrodes, and link current into the test; 3) measure resistance based on Principle V and calculate the corresponding resistivity value. The invention takes the entire face of the sample as current access electrode; and central surface electrode as voltage test electrode. Save the tedious process of ordinary electrode testing method embedding electrodes and dispel the one-sidedness of ordinary electrode voltage testing. Test the voltage drop of the sample voltage electrode more accurately.
Description
Technical field
The present invention relates to civil engineering material technical field, be specifically related to the method for a kind of accurate measurement conductive cement base material volume resistance or resistivity.
Background technology
Conductive cement base material is by mixing the new function material that conductive material (carbon fiber, carbon black, steel fibre, conducting polymer) prepares as conductivity water mudstone, electric conduction mortar, conducting concrete etc.And the carbon-fiber cement sill is the conductive cement base material of wherein studying and being most widely used.Conductive cement base material has the function of many uniquenesses, as has the function and the thermoelectric effect of self-induction stress, strain, temperature and have temperature, be out of shape self-regulating function.Desirable conductive cement base material must possess good stable electric property.Yet because the complicacy of the conductive mechanism of conductive cement base material inside, making not only has ionic conduction, electronic conduction, hole conduction coexistence the drift of charge carrier, but also has tunneling effect.The resistance or the resistivity of therefore how to demarcate conductive cement base material are to perplex people's a technical barrier for a long time.
The domestic and international at present specific insulation method of testing to conductive cement base material mainly contains the two poles of the earth method (directly testing Ohmage) and four-electrode method (utilizing a volt-ampere principle test resistance).Because there is a large amount of conductive ions cement material inside, directed moving can be taken place under the electric field force effect, produce polarization effect, it is bigger to use the two poles of the earth method to measure time error; And the measurement of common four-electrode method must be at inner pre-buried four electrodes of cement-based material, the different of its electrode position and size have bigger difference (error surpasses 10%) to the last test result, are difficult to accurately measure and evaluate the true resistance rate of conductive cement base material.
Summary of the invention
The method that the purpose of this invention is to provide a kind of accurate measurement conductive cement base material volume resistance or resistivity.
The technical scheme that realizes the object of the invention is as follows:
A kind of method of measuring volume resistance rate of conductive cement base material adopts four electrodes, utilizes the volt-ampere principle to measure testing sample resistance earlier, measures the resistivity value of sample then according to the resistivity formula, has following steps:
1), choose cement-based material sample to be measured, and carry out pre-service;
2), insert electrode as measuring current, as the voltage tester electrode, feed measuring current with two the parallel anchor rings in sample middle part with two end faces of testing sample;
3), measure resistance value, calculate corresponding resistivity value according to the volt-ampere principle.
Testing sample is rectangular parallelepiped or right cylinder in the described step 1), and its preprocessing process comprises:
(1) laitance of sample surfaces is removed in polishing, cleans the precompose electrode area with acetone, and moisture is removed in oven dry;
(2), and toast once more, cool off at two anchor ring coated with conductive silver of two end faces of sample and middle part slurry.
The mass percent 60%~65% of silver powder in the described silver slurry, resistance per square is less than 10m Ω/ /25.4 μ m.
Described silver slurry has applied sends into baking oven, and to being solidificated in the testing sample surface to the silver slurry, oven temperature is controlled at below 150 ℃.
The silver slurry thickness that testing sample electrode place applies is 0.1mm, and wherein middle part anchor ring width is 3mm.
The strength of current of the measuring current that feeds described step 2) is not higher than 10mA.
In this method test process, adjust different measuring currents and carry out 3 measurements respectively, draw the average test value then.
Good effect of the present invention has: 1) the present invention inserts electrode with the whole end face of testing sample as electric current, has guaranteed conductive cement base material inner conductive stability of network; As the voltage tester electrode, both save the loaded down with trivial details technology that common 4 electrode methods need pre-buried electrode with the anchor ring electrode, and eliminated the one-sidedness of common 4 electrode method voltage testers again, end face tests out the voltage drop between the sample voltage electrode more accurately entirely.
2) the present invention is a kind of improved 4 electrode methods, and 4 common electrode methods depend on the size and the position of electrode, often causes measuring error big (reaching 10%); And this law is by rationally being provided with electrode, and the test data accuracy height of acquisition, error are little, the specific insulation of the conductive cement base material of its measurement, and error is less than 0.5%.
3) the present invention adopts that electric conductivity is stable, the conductive silver paste of strong adhesion is as electrode, has not only made things convenient for measurement, and because silver slurry excellent conducting performance makes test data stable, has finely satisfied conductive cement base material grade estimation requirement.
Description of drawings
Fig. 1 is the installation site synoptic diagram of shape, size and the test electrode of sample of the present invention.
Embodiment
The prepared in laboratory carbon fiber volume content is respectively 0.3%, 0.5%, 0.8% positive rectangular parallelepiped sand-cement slurry as testing sample, and sample size is 40 * 40 * 160mm
3(sand-cement slurry of certainly selecting right cylinder or other rectangular shapes is as testing sample, and its method of testing is identical, and corresponding last measured resistivity value is also consistent).Maintenance was taken out after 28 days under standard environment (20 ± 3 ℃ of temperature, relative humidity is greater than 95%), left standstill under room temperature environment 4 hours.
Mark the position that anchor ring voltage tester electrode is set at the about 50mm of distance sample both ends of the surface place; With two end faces and the anchor ring voltage tester electrode area of sand papering sample, the about 2mm of grinding depth cleans with acetone then, place in 80 ℃ of baking ovens, toasted 20 minutes, and after taking-up is cooled to room temperature, began to make anchor ring voltage tester electrode and end face electric current and insert electrode.As shown in Figure 1, the conductive silver paste of two about 0.1mm of end face coating thickness, the electric current that forms end face inserts electrode; Anchor ring voltage tester electrode place, two middle parts applies wide about 3mm, and the conductive silver paste of thick 0.1mm forms the voltage tester electrode; The quality of cathode silver number percent of above-mentioned conductive silver paste is 60%~65%, and its resistance per square is less than 10m Ω/ /25.4 μ m; Send into baking oven after coating is finished once more and toasted 30 minutes in 80 ℃ of temperature, baking is stable to be controlled at below 150 ℃, takes out and is cooled to room temperature, and the test electrode of testing sample just completes.
As shown in Figure 1, insert the permanent steady electric currents (less than 10mA) of electrodes input at two end face electric currents of testing sample, simultaneously with the potential difference (PD) between two anchor ring electrodes of pot test, recording voltage~current data group.Adjust different strength of current and measure once more, obtain two groups of correspondent voltage~current data group.Can obtain the volume resistance of sample according to formula R=U/I (R is that resistance, U are that potential difference (PD), I are strength of current in the formula).Measure face area and two anchor ring distance between electrodes of testing sample, can obtain the specific insulation of sample according to formula ρ=RS/L (be resistivity, S is an area, and L is a length).
Table 1 is test data and result thereof in the embodiment of the invention, and the data from table as can be known, and are little with the specific insulation error range of the inventive method measurement conductive cement base material, are controlled in 0.5%.
Numbering | 1# | 2# | 3# |
Carbon fiber volume content (vol.%) | 0.3 | 0.5 | 0.8 |
Strength of current I 1 (mA) | 5.0 | 5.0 | 5.0 |
Potential difference (PD) U 1 (mV) | 769.35 | 257.60 | 63.30 |
Strength of current I 2 (mA) | 7.0 | 7.0 | 7.0 |
Potential difference (PD) U 2 (mV) | 1077.44 | 360.78 | 88.83 |
Strength of current I 3 (mA) | 9.0 | 9.0 | 9.0 |
Potential difference (PD) U 3 (mV) | 1387.08 | 464.13 | 113.49 |
Average resistance R (ohm) | 153.97 | 51.54 | 12.65 |
End area S (cm 2) | 16 | 16 | 16 |
Length L (cm) | 6 | 6 | 6 |
Average resistivity (ohmcm) | 410.59 | 137.45 | 33.74 |
Table 1
Claims (7)
1, a kind of method of measuring volume resistance rate of conductive cement base material is characterized in that: have following steps:
1), choose cement-based material sample to be measured, and carry out pre-service;
2), insert electrode as measuring current, as the voltage tester electrode, insert measuring current in the sample two ends with two the parallel anchor rings in sample middle part with two end faces of testing sample;
3), measure resistance value according to the volt-ampere principle: R=U/I, wherein R is that resistance, the U of sample between two anchor ring electrodes are that two potential difference (PD), I between the anchor ring electrode are the strength of current by sample;
And calculate corresponding resistivity value: ρ=RS/L, and wherein ρ is the resistivity of sample, and S is the area of section of sample, and L is the length of sample between two anchor ring electrodes.
2, the method for measurement volume resistance rate of conductive cement base material according to claim 1 is characterized in that: testing sample is rectangular parallelepiped or right cylinder in the described step 1), and its preprocessing process comprises:
(1) laitance of sample surfaces is removed in polishing, cleans the precompose electrode area with acetone, and moisture is removed in oven dry;
(2), and toast once more, cool off at two anchor ring coated with conductive silver of two end faces of sample and middle part slurry.
3, the method for measurement volume resistance rate of conductive cement base material according to claim 2 is characterized in that: the mass percent of silver powder is 60%~65% in the described silver slurry, and the resistance per square of described silver slurry is less than 10m Ω/mouth/25.4 μ m.
4, the method for measurement volume resistance rate of conductive cement base material according to claim 2 is characterized in that: described silver slurry has applied sends into baking oven, is solidificated in the testing sample surface until the silver slurry, and oven temperature is controlled at below 150 ℃.
5, the method for measurement volume resistance rate of conductive cement base material according to claim 2 is characterized in that: the silver slurry thickness that testing sample electrode place applies is 0.1mm, and wherein middle part anchor ring width is 3mm.
6, the method for measurement volume resistance rate of conductive cement base material according to claim 1 is characterized in that: the strength of current of the measuring current that feeds described step 2) is not higher than 10mA.
7, the method for measurement volume resistance rate of conductive cement base material according to claim 1 is characterized in that: in this method test process, adjust different measuring currents and carry out 3 measurements respectively, draw the average test value then.
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CN102680791B (en) * | 2012-05-24 | 2015-05-13 | 重庆市防雷中心 | Automatic test system for resistance reducing agent resistivity and power frequency current tolerance test |
CN102854392A (en) * | 2012-09-04 | 2013-01-02 | 中国能源建设集团广东省电力设计研究院 | Method and device for measuring indoor resistivity of soil sample |
CN103018568B (en) * | 2012-12-07 | 2015-06-03 | 黄瑞哲 | Resistivity measuring method of rock test block with stable moisture content |
CN104345216A (en) * | 2014-10-29 | 2015-02-11 | 中国建筑材料科学研究总院 | Method and device for measuring specific resistance and 28-day strength of cement |
CN104678181B (en) * | 2015-03-23 | 2017-09-29 | 攀钢集团研究院有限公司 | Rail resistance rate measuring method |
CN104714097B (en) * | 2015-04-02 | 2018-01-09 | 中国矿业大学(北京) | A kind of cement-based material resistivity on-line determination instrument |
CN106706406B (en) * | 2017-01-23 | 2019-04-30 | 河海大学 | Cement-based material for being embedded into electrode forms die trial |
CN108051480A (en) * | 2017-12-29 | 2018-05-18 | 中冶建筑研究总院有限公司 | A kind of grouting material plumpness detection method and device and grout sleeve |
CN112433096A (en) * | 2019-08-26 | 2021-03-02 | 南京工程学院 | Method for testing resistivity of conductive concrete in loading process |
CN111596000A (en) * | 2020-04-17 | 2020-08-28 | 南京航空航天大学 | Testing device and method for electro-osmosis dehumidification and corrosion prevention of conductive mortar |
CN111856141A (en) * | 2020-07-29 | 2020-10-30 | 深圳前海中瑞智能技术开发有限公司 | Cement-based resistivity detection system and method |
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