CN101886954A - Cement-based temperature sensing element for positive and negative temperature automatic measurement - Google Patents
Cement-based temperature sensing element for positive and negative temperature automatic measurement Download PDFInfo
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- CN101886954A CN101886954A CN 201010222211 CN201010222211A CN101886954A CN 101886954 A CN101886954 A CN 101886954A CN 201010222211 CN201010222211 CN 201010222211 CN 201010222211 A CN201010222211 A CN 201010222211A CN 101886954 A CN101886954 A CN 101886954A
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Abstract
The invention discloses a cement-based temperature sensing element for positive and negative temperature automatic measurement. The cement-based temperature sensing element comprises a test block and a pair of electrodes, wherein, the electrodes are respectively positioned on the upper surface and the lower surface of the test block, and the test block comprises a cement matrix and conductive fiber which is evenly distributed in the cement matrix; the cement matrix comprises alite-barium calcium sulphoaluminate cement and sand; and the conductive fiber is composed of chopped polypropolefin carbon fiber and a carbon nanotube. The cement-based temperature sensing element of the invention has the beneficial effects: 1. the alite-barium calcium sulphoaluminate cement is taken as the cement matrix, and the carbon nanotube expands the temperature measurement range of the temperature sensing element below a freezing point; and 2. the capacitive signal of the sensing element is sensitive to temperature change, thus stable data can be acquired through multiple repeated measurement.
Description
Technical field
The present invention relates to the sensing element in a kind of detection technique field, particularly a kind ofly be used to monitor that the mass concrete internal temperature changes and can be used for the cement based temperature-sensing element that positive subzero temperature is tested oneself with mass concrete combines together.
Background technology
Temperature has remarkable influence and effect to the stress of large volume concrete structural, and the research of structure temperature field and internal temperature gradient occupies more and more important position in the research of modern project structure detection.The measurement of Temperature Field in Bulky Concrete is no matter be in construction period or run duration all has crucial meaning.In construction period, nearly all large volume concrete structural all will take measures to carry out temperature control, reduces thermograde in the structure, prevents that the crack from taking place, and guarantees one-piece construction safety; At run duration, temperature load is the one of the main reasons that causes dam deformation and STRESS VARIATION.Therefore, in time and exactly obtaining the temperature field information of dam concrete inside configuration, is the key of massive concrete construction control, also is one of important content of mass concrete run duration safety monitoring.
Yet, the temperature survey of mass concrete, usually need pre-buried temperature sensor to carry out temperature monitoring, it is how not enough that this brings for actual engineering operation, mainly show as: a temperature sensor is measured the temperature of a point only, wants mass concrete is carried out multimetering, needs pre-buried a plurality of temperature sensors, this stress that will cause a plurality of positions of structure reduces, and influences the permanance of xoncrete structure greatly; The environmental requirement height of this class sensor to working, poor durability, tenure of use is low, and cost is high relatively, needs continuous replacing simultaneously in the use of xoncrete structure, improves construction costs greatly; Temperature sensing modulator material and concrete material poor performance can accurately not measured the temperature of large volume concrete structural.Therefore, but invention can compatible multimetering with mass concrete not influence structure durability, long service life, cost is low and can realizes that the cement based temperature-sensing element that temperature is tested oneself seems very necessary and urgent.
The researcher finds both at home and abroad, and chopped carbon fiber is joined in the cement concrete, can give concrete good responsive to temperature characteristic.For example, clocklike reducing appears in the concrete resistivity that is mixed with an amount of carbon fiber with the rising of environment temperature, i.e. temperature resistance characteristic; An amount of carbon fiber can make concrete become semiconductor material, has Seebeck effect, specially CN200610024718 utilizes the Seebeck effect of carbon fiber reinforced concrete to make the clever concrete sensor component that temperature is tested oneself, and the temperature Centralized that this sensing element is measured is between 0 ℃～150 ℃.
The environment temperature of actual mass concrete can change in positive and negative temperature range, minimum temperature especially, and in the winter or the highlands of cold, the minimum temperature of environment can reach between-15 ℃～-20 ℃.For example, the fate of Qinghai-Tibet Platean year positive and negative alternating temperature is up to 180d, and temperature difference per day can reach 30 ℃.Therefore, research can be used for positive and negative temperature measurement, under positive subzero temperature acts on repeatedly, still have good durability to can be used for the cement based temperature-sensing element that positive subzero temperature tests oneself significant.The temperature-measuring range of present temperature-sensing element also is confined to above zero, and the resistance signal by measuring sensing element is as the electric signal of sense ambient temperature, repeatedly repeated measurement data instability.
Summary of the invention
For the temperature-measuring range that solves present temperature-sensing element also is confined to above zero, the unsettled drawback of repeated measurement data repeatedly; The invention provides a kind of cement based temperature-sensing element that positive subzero temperature is tested oneself that can be used for.
The present invention realizes by following measure:
Of the present inventionly can be used for the cement based temperature-sensing element that positive subzero temperature is tested oneself, comprise test block and pair of electrodes, described electrode lays respectively at the upper surface and the lower surface of test block, and its special special feature is: described test block comprises cement matrix and the conductive fiber that is evenly distributed in the cement matrix; Described cement matrix comprises A Lite-barium-bearing calcium sulfo-aluminate cement and sand, and described conductive fiber cuts the polypropylene/olefin carbon fiber by weak point and carbon nano-tube is formed.
Above-mentioned can be used for the cement based temperature-sensing element that positive subzero temperature is tested oneself, the percentage by weight of each ore deposit phase system is in described A Lite-barium-bearing calcium sulfo-aluminate cement clinker:
Barium-bearing calcium sulfo-aluminate 3-37%
Tricalcium silicate 30-60%
Dicalcium silicate 15-40%
Tricalcium aluminate 15-40%
Tetra calcium aluminoferrite 3-20%.
Above-mentioned can be used for the cement based temperature-sensing element that positive subzero temperature is tested oneself, the weight of described test block consists of:
Cement matrix: 98.5-99.5%
Short polypropylene/olefin carbon fiber: the 0.4%-1% that cuts
Carbon nano-tube: 0.1%-0.8%.
Above-mentioned state can be used for the cement based temperature-sensing element that positive subzero temperature is tested oneself, described weak point is cut the polypropylene/olefin carbon fiber and is: length 10-15mm, diameter 7 ± 0.2 μ m, line resistance 85 Ω/m, stretch modulus 175-215/Gpa.
Above-mentioned can be used for the cement based temperature-sensing element that positive subzero temperature is tested oneself, described carbon nano-tube is: overall diameter 20-40nm, internal diameter 5-10nm, length 50 μ m, specific surface area 110m
2/ g, density 2.1g/cm
3
The present invention adopts A Lite-barium-bearing calcium sulfo-aluminate cement as cement matrix, mainly based on following reason, this cement is mainly formed still similar with the Portland cement composition, has guaranteed that the matrix of temperature-sensing element and large volume concrete structural have excellent compatibility; Simultaneously, the barium-bearing calcium sulfo-aluminate mineral have the microdilatancy characteristic, can reduce the porosity of temperature-sensing element, guarantee that element has good frost resistance, guarantee the accuracy of measuring-signal under positive negative temperature acts on repeatedly; Compensate the drying shrinkage of cement matrix simultaneously, reduce check crack, improve the permanance of sensing element.
The present invention is by the capacitance signal of measurement sensing element, but not resistance signal is as the electric signal of sense ambient temperature.This is because capacitance signal is compared with resistance signal, has the characteristics sensitive, good stability that change.That is to say, utilize the temperature-capacitance characteristic of sensing element to measure the environment temperature of xoncrete structure.Conductive fiber in the sensing element comprises chopped carbon fiber and carbon nano-tube, these conductive materials form many capacitors in cement matrix, wherein form relatively large capacitor between the carbon fiber, and form the more capacitor of microcosmic between the carbon nano-tube, thereby further strengthen the capacitance of whole temperature-sensing element at microcosmos area.Rising along with temperature, more charge carrier is owing to thermal excitation participates in conduction in the element, these charge carriers make the capacitance of sensing element constantly raise owing to the existence of numerous capacitors is adsorbed, can perception sensing element environment temperature on every side by the electric capacity of survey sensor.
Because principal ingredient of the present invention is the potpourri of A Lite-barium-bearing calcium sulfo-aluminate cement and sand, permanance is good, and has good compatibility with the large volume cement concrete.Can directly the present invention be placed in the mass concrete during use, mounting process is simple, simultaneously can be according to the requirement at the position of detecting, and the size that changes sensor is with the convenient temperature that detects required detection mass concrete position.
The invention has the beneficial effects as follows: 1. adopt A Lite-barium-bearing calcium sulfo-aluminate cement as cement matrix, quoting of carbon nano-tube makes the temperature-measuring range of temperature-sensing element expand to below freezing; 2. this sensing element capacitance signal is to the temperature variation sensitivity, and repeatedly repeated measurement data is stable.
Description of drawings
Fig. 1: can be used for the cement based temperature-sensing element permittivity variation that positive subzero temperature is tested oneself at-45 ℃ of-90 ℃ of 1# and 2#.
Fig. 2: can be used for cement based temperature-sensing element that positive subzero temperature tests oneself permittivity under temperature conditions repeatedly at-45 ℃ of-90 ℃ of 2# and change.
Embodiment
Table 1 A Lite-barium-bearing calcium sulfo-aluminate cement performance
The short polypropylene/olefin carbon fiber performance parameter of cutting of table 2
The performance parameter of table 3 carbon nano-tube
Each ore deposit phase system ratio (wt%) of table 4 A Lite-barium-bearing calcium sulfo-aluminate cement clinker
Preparation is as the A Lite-barium-bearing calcium sulfo-aluminate cement of physicochemical property as described in table 1, table 2, table 3 and the table 4, short polypropylene/olefin carbon fiber and the carbon nano-tube of cutting.Short cut that the polypropylene/olefin carbon fiber cleans, dried, a certain proportion of weak point is cut the polypropylene/olefin carbon fiber join in the methocel solution, stir with glass bar and guarantee that the short polypropylene/olefin carbon fiber of cutting disperses fully; Simultaneously carbon nano-tube is joined in the neopelex solution and disperse, again above-mentioned two kinds of solution are poured in the agitated kettle and stirred, add entry by water cement ratio 0.35, beta-naphthalenesulfonic-acid salt water reducer (water weight 3 ‰), tbp defoamer (water weight 2 ‰), add cement then in batches and (add normal sand simultaneously, aggregate-to-cement ratio is 3: 1), after stirring 4min, injection forming in the standard mortar mould, imbed copper net electrode, jolt ramming, sample is put into standard curing room, and (temperature is 20 ± 1 ℃, relative humidity 〉=90%) maintenance, put into water behind the 1d and continue maintenance 28d, temperature-sensing element is made in vacuum drying.Wherein sand-cement slurry accounts for 98.5-99.5% in the temperature-sensing element, and weak point is cut the polypropylene/olefin carbon fiber and accounted for 0.4%-1%, and carbon nano-tube accounts for 0.1%-0.8%.Fig. 1 is a sensing element permittivity change curve in-45 ℃ of-90 ℃ of temperature ranges, repeatedly duplicate measurements, and its capacitance data is stable, and amplitude of variation is obvious.Sample raw material proportioning sees Table 5:
Table 5 sample raw material proportioning (wt%)
Fig. 1 can be used for cement based temperature-sensing element permittivity that positive subzero temperature tests oneself with the variation of temperature curve for 1# in-45 ℃ of-90 ℃ of scopes and 2#.As seen from Figure 1, the 1# element of carbon-doped nanometer tube is not obvious in the subzero capacitance variations, compare with the 2# element that mixes carbon nano-tube simultaneously, its integral capacitor changes irregular, therefore, the introducing of carbon nano-tube can make the measurement range of temperature element expand to subzero, and DATA REASONING is more regular and stable.
Fig. 2 can be used for cement based temperature-sensing element permittivity that positive subzero temperature the tests oneself change curve under temperature variation condition repeatedly for 2# in-45 ℃ of-90 ℃ of scopes.As seen from Figure 1, the temperature-capacitance curve of sample is repeatedly showing good temperature-capacitance characteristic under the temperature cycles effect, and only the 1st circulation differs bigger with other 3 round-robin temperature-capacitance curves.This be because: after the temperature cycles 1 time, sensing element inside just has part moisture and is dried, and moisture reduces in the sample, has reduced the inside of temperature-sensing element and can cause temperature-capacitance curve to descend for the amount of ions of polarization; Wherein the 1st temperature cycles sample moisture is dried at most, so its capacitance curve and differ bigger other 3 times.It can also be seen that by Fig. 1 along with the increase of cycle index, sensing element temperature-capacitance curve is linear to remain unchanged substantially, shows better repeatability.Temperature-sensing element data variation amplitude is big, and electric capacity rises with temperature and changes acumen, and data variation repeatability is strong, and is obviously regular.The introducing of carbon nano-tube has enlarged the temperature measurement range of temperature-sensing element, to subzero.
Claims (5)
1. one kind can be used for the cement based temperature-sensing element that positive subzero temperature is tested oneself, comprise test block and pair of electrodes, described electrode lays respectively at the upper surface and the lower surface of test block, it is characterized in that: described test block comprises cement matrix and the conductive fiber that is evenly distributed in the cement matrix; Described cement matrix comprises A Lite-barium-bearing calcium sulfo-aluminate cement and sand, and described conductive fiber cuts the polypropylene/olefin carbon fiber by weak point and carbon nano-tube is formed.
2. according to claim 1ly can be used for the cement based temperature-sensing element that positive subzero temperature is tested oneself, it is characterized in that: the percentage by weight of each ore deposit phase system is in described A Lite-barium-bearing calcium sulfo-aluminate cement clinker:
Barium-bearing calcium sulfo-aluminate 3-37%
Tricalcium silicate 30-60%
Dicalcium silicate 15-40%
Tricalcium aluminate 15-40%
Tetra calcium aluminoferrite 3-20%.
3. according to claim 1ly can be used for the cement based temperature-sensing element that positive subzero temperature is tested oneself, it is characterized in that: the weight of described test block consists of:
Cement matrix: 98.5-99.5%
Short polypropylene/olefin carbon fiber: the 0.4%-1% that cuts
Carbon nano-tube: 0.1%-0.8%.
4. according to claim 1ly can be used for the cement based temperature-sensing element that positive subzero temperature is tested oneself, it is characterized in that: described weak point is cut the polypropylene/olefin carbon fiber and is: length 10-15mm, diameter 7 ± 0.2 μ m, line resistance 85 Ω/m, stretch modulus 175-215/Gpa.
5. according to claim 1ly can be used for the cement based temperature-sensing element that positive subzero temperature is tested oneself, it is characterized in that: described carbon nano-tube is: overall diameter 20-40nm, internal diameter 5-10nm, length 50 μ m, specific surface area 110m
2/ g, density 2.1g/cm
3
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Cited By (5)
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| RU2472753C1 (en) * | 2011-06-21 | 2013-01-20 | Общество с ограниченной ответственностью "Теконит" | Method of producing crude mixture for making foam concrete |
| CN103674300A (en) * | 2013-11-26 | 2014-03-26 | 河海大学 | Manufacturing method for temperature sensor |
| CN104496231A (en) * | 2014-12-29 | 2015-04-08 | 桂林理工大学 | Method for preparing high-ferric Alite-calcium barium sulphoaluminate cement by using red mud and barium mud |
| CN106673564A (en) * | 2017-02-22 | 2017-05-17 | 青岛理工大学 | Intelligent concrete for GO (graphene oxide) strengthened CNT (carbon nano tube) precoated sand, wireless sensor and preparation method |
| CN113480263A (en) * | 2021-07-24 | 2021-10-08 | 陕西秦汉恒盛新型建材科技股份有限公司 | 3D printing concrete prepared from recycled aggregate and preparation method thereof |
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| CN1451955A (en) * | 2003-05-22 | 2003-10-29 | 武汉理工大学 | High-sensitivity carbon fibre cement based resistance strain sensing system comprising temp. compensation |
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| CN1513786A (en) * | 2003-08-14 | 2004-07-21 | 济南大学 | Alite-barium calcium sulfur aluminate cement |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2472753C1 (en) * | 2011-06-21 | 2013-01-20 | Общество с ограниченной ответственностью "Теконит" | Method of producing crude mixture for making foam concrete |
| CN103674300A (en) * | 2013-11-26 | 2014-03-26 | 河海大学 | Manufacturing method for temperature sensor |
| CN104496231A (en) * | 2014-12-29 | 2015-04-08 | 桂林理工大学 | Method for preparing high-ferric Alite-calcium barium sulphoaluminate cement by using red mud and barium mud |
| CN104496231B (en) * | 2014-12-29 | 2016-07-06 | 桂林理工大学 | A kind of method utilizing red mud and the clay standby high ferro Alite-barium calcium sulphoaluminate of barium |
| CN106673564A (en) * | 2017-02-22 | 2017-05-17 | 青岛理工大学 | Intelligent concrete for GO (graphene oxide) strengthened CNT (carbon nano tube) precoated sand, wireless sensor and preparation method |
| CN106673564B (en) * | 2017-02-22 | 2019-09-24 | 青岛理工大学 | Intelligent concrete, wireless sensor and the preparation method of GO enhancing CNT precoated sand |
| CN113480263A (en) * | 2021-07-24 | 2021-10-08 | 陕西秦汉恒盛新型建材科技股份有限公司 | 3D printing concrete prepared from recycled aggregate and preparation method thereof |
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Open date: 20101117 |