CN100578221C - Method and apparatus for measuring rapid drying shrinkage of cement-based material - Google Patents

Method and apparatus for measuring rapid drying shrinkage of cement-based material Download PDF

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CN100578221C
CN100578221C CN200510112560A CN200510112560A CN100578221C CN 100578221 C CN100578221 C CN 100578221C CN 200510112560 A CN200510112560 A CN 200510112560A CN 200510112560 A CN200510112560 A CN 200510112560A CN 100578221 C CN100578221 C CN 100578221C
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valve
water
vacuum
measuring chamber
temperature
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CN1763525A (en
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赵顺增
郑万廪
刘立
姚燕
杨东升
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China Building Materials Academy CBMA
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China Building Materials Academy CBMA
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Abstract

The invention relates to a drying contraction measuring method and specific device of cement base material, which comprises the following steps: 1) setting a vacuum measuring room within thermostatic water-bath jacket to control the working temperature and relative dampness of detected cement base material, which affirms the drying contraction value; 2) affirming the quality, shape and temperature variation value of relative dampness trimmed value in the measuring room. The device contains measuring bulk, control console, vacuum pump, water pot and constant temperature water circulation pump, wherein the vacuum pump and water pot outlet pierce the measuring bulk through their own pipe, which connect the cave; the constant temperature water circulation pump connects the measuring bulk through two pipes.

Description

Dry measuring method and the device thereof of shrinking of cement-based material
Technical field
The present invention relates to a kind of measuring method and device thereof, specifically is dry measuring method and the device thereof of shrinking of a kind of cement-based material.Be applicable to and measure cement-based material rapid draing shrinkage value under the temperature and humidity conditions of regulation.
Background technology
In the cement-based material research field, the dry contraction is an important performance of cement concrete, it has very large influence to the endurance quality of concrete and reinforced concrete structure, the crack problem that is caused by the dry contraction of concrete has been the building problem of generally acknowledging, never way solves for a long time.
Moisture in the cement-based material reaches dry the contraction by diffusive equilibrium needs long time, the dry shrinkage test cycle very long (generally being 180 days) of therefore general cement-based material, testing expenses are than higher, this has just restricted this field innovative research result's generation speed, cause when performances such as workability of concrete, intensity all obtain prominent development, the volume stability Journal of Sex Research but lags behind always.So no matter be to detect from daily product, still the angle researched and developed of new material is said, presses for a kind of cement-based material hydrated properties that neither influences, fast and convenient again test method.
Summary of the invention
Problem set forth above, the problem to be solved in the present invention just, purpose of the present invention will provide a kind of high-precision cement-based material rapid draing to shrink measuring method and device thereof exactly.
For achieving the above object, the present invention by the following technical solutions: a kind of cement-based material rapid draing measuring method, it is characterized in that: it comprises the steps:
1) by a working temperature and a relative humidity that is arranged with the vacuum measurement chamber control cement-based material test specimen to be measured of water bath with thermostatic control chuck, with the drying shrinkage value of this test specimen to be measured of displacement sensor;
2) by mass change value, length variations value and temperature change value to definite acquisition test specimen to be measured of relative humidity equilibrium value under the working temperature in the measuring chamber;
Concrete operations are as follows:
A) working temperature of measuring chamber is set, the thermostatted water ebullator by a peripheral hardware injects thermostatted water in described water bath with thermostatic control chuck, and this thermostatted water circulates in its water bath with thermostatic control chuck;
B) open the measuring chamber loam cake, load described test specimen to be measured, this test specimen to be measured bottom contacts with a force cell, and the top contacts with a displacement transducer, the attached temperature sensor of outside surface card;
C) sealing measuring chamber top cover, vacuum pump and water pot by peripheral hardware alternately start the air of getting rid of in the measuring chamber, and charging into water vapour, the standard of deaeration is that at this moment the air content in the measuring chamber should can be thought to reach the measurement vacuum state that needs below 2%; Demonstrate steam partial pressure P in the measuring chamber by vacuum meter iBy following formula, determine described relative humidity RH; Its formula is:
RH = P i P 0 × 100 %
Wherein: P 0Water saturation vapour pressure when-temperature is t
The surface temperature of the test specimen to be measured that t-is in good time
When temperature t is controlled at 10～30 ℃, calculate saturated vapor pressure P by following formula 0
P 0＝670.76e 0.062t
Wherein: e=2.718
Above-mentioned thermostatted water can carry out accuracy controlling in 10～30 ℃ of scopes, error is ± 0.1 ℃; Working temperature in this measuring chamber is 20 ± 0.1 ℃.
After above-mentioned relative humidity RH determines, force cell described in the step b), displacement transducer and temperature sensor get access to length variations value, mass change value and the temperature change value of this test specimen to be measured on described test specimen to be measured, by transmission line above-mentioned measurement result is sent into control desk and carry out analyzing and processing.
In order to realize above-mentioned cement-based material rapid draing contraction measuring method, another object of the present invention also provides a kind of special measurement device, and its characteristics are: it comprises measurement mechanism body, control desk, vacuum pump, water pot and thermostatted water ebullator; Described measurement mechanism body is that two layers of being provided with base plate and upper cover plate overlap tubulars, and upper cover plate is positioned at the top of two layers of sleeve, on its upper cover plate vacuum meter is housed; The internal layer tube of two layers of sleeve is a measuring chamber, and outer layer sleeve is a water bath with thermostatic control chuck, and base plate and upper cover plate are the sealing shape with two layers of sleeve sealing; One has the support frame of lower and upper cross-member and two vertical rods, hangs down to being located at this measuring chamber middle part; One displacement transducer, it is arranged on described support frame entablature upside; One force cell is installed on described support frame sill upside, leaves the position of placing cement-based material test specimen to be measured under the described displacement transducer between contact and the described force cell upper surface; Two temperature sensors are attached on the vertical rod inboard of described framework one side respectively and on the outside surface of test specimen to be measured.Described measurement mechanism body bottom is provided with bracing frame; Described vacuum pump output terminal and water pot output terminal are communicated with in the base plate of described measurement mechanism body and with this measuring chamber by pipeline break-through separately respectively; The pipeline middle part that described vacuum pump output terminal is connected with its measurement mechanism body is provided with vacuum valve, described water pot output terminal connects a threeway, the pipeline middle part that the one port is communicated with described measurement mechanism body is provided with the water pot valve, and another port vertical end upside is equipped with an exhaust and inlet valve; Described thermostatted water ebullator feeds described outer layer sleeve respectively by inlet channel and outlet conduit barrel is communicated with described water bath with thermostatic control chuck, forms a circulation waterway.
Above-mentioned measuring chamber is the vacuum shape, described displacement transducer be in laser displacement sensor, grating displacement sensor or the capacitive displacement transducer any, described control desk is collection, analysis, the integrated computing machine of output function software.
The material of above-mentioned water bath with thermostatic control chuck wallboard and described vacuum shape measuring chamber wallboard can adopt stainless steel or common iron manufacturing.
Also be provided with a molecular sieve adsorption trap that is used to adsorb steam and oil gas between above-mentioned vacuum pump and the vacuum valve.
Above-mentioned vacuum valve, water pot valve, exhaust and inlet valve can select for use simultaneously the manual shutdown valve of high vacuum, electromagnetism shutdown valve, electromagnetism cut off air release, fine setting needle-valve, manually in air release or the electric current pneumatic valve any, also can select for use different valve combination to use, be used for the indoor water vapor pressure of control survey.
Above-mentioned vacuum meter can be selected any in film vacuum meter, thermocouple vacuum gauge, compound vacuum gauge, ohmer, silicone oil pressure gauge, the mercury manometr for use.
Above-mentioned control desk is connected with vacuum valve, water pot valve, displacement transducer, force cell, temperature sensor and vacuum meter respectively by the interface line.
The present invention is owing to adopt above method, it has the following advantages: 1, the present invention is by the method for forvacuum, eliminated of the influence of air dividing potential drop to relative humidity, evaporation process by moisture in the pressure equilibrium control test sample to be tested of water vapor, realize the moisture rapid evaporation in the test specimen to be measured, reached quick-drying purpose; 2, compare with heating rapid evaporation drying, the present invention can not form cement hydration process and disturb, and can not produce bigger temperature deformation influence; 3, the present invention can control the probe temperature and the humidity of cement-based material more accurately, and can regulate different probe temperatures and humidity as required, has solved insurmountable always for a long time accurate prediction environmental problem; 4, the present invention can be under same test environment, measure length, quality and the temperature variation of tested sample, it is many to have test parameter, and the data of being gathered are imported the processing of computing machine collective analysis into, thereby can be than the physical change form of more comprehensive understanding cement-based material in dry run; 5, equipment therefor precision height of the present invention, test data is accurate, can finish the test job that classic method needs half a year even several years in time a couple of days, can save the wide variety of materials expense, test fee and time, the R﹠D cycle that shortens new material is significant.
Description of drawings
Fig. 1 is a proving installation structural representation of the present invention
Embodiment
At first theoretical foundation of the present invention and result of study are carried out comparatively detailed introduction.
According to the molecular thermalmotion theory, when the molecular energy of liquid surface during greater than the potential barrier of liquid, will leave liquid level becomes steam molecule; Steam molecule in the environment will condense with the liquid level collision because of thermal motion and be liquid.Actual observation to macroscopical evaporation process be the evaporation of microcosmic and the summation of coacervation process.When the evaporation of microcosmic was equal with cohesion speed, the evaporation process of macroscopic view stopped, and this moment, the humidity of environment was saturated humidity.When ambient humidity during less than saturated humidity, the evaporation process of macroscopic view just takes place, otherwise, the coacervation process of macroscopic view just takes place.According to the formula of statistical thermodynamics, microcosmic velocity of evaporation v 1Function for liquid molecular heat of vaporization Q, temperature T, liquid surface area S:
v 1＝K 1Se -Q/RT
K in the formula 1Be the velocity of evaporation constant, R is a gas law constant.Velocity of evaporation V with unit area 1Represent, just can be write as following formula:
V 1＝K 1e -Q/RT
Microcosmic cohesion speed v 2Function for ambient humidity P (representing), temperature T, liquid surface area S with water vapor pressure:
v 2 = ( M 2 πRT ) 1 / 2 SP
Cohesion speed V with unit area 2Represent, just can be write as following formula:
V 2 = ( M 2 πRT ) 1 / 2 P
M is the gram molecular weight of liquid in the formula.Work as V 1=V 2The time, P should be P c, then:
K 1 e - Q / RT = ( M 2 πRT ) 1 / 2 P c
P c = ( 2 πRT M ) 1 / 2 K 1 e - Q / RT
The macroscopic view velocity of evaporation then is:
V = V 1 - V 2 = K 1 e - Q / RT - ( M 2 πRT ) 1 / 2 P
And P=RHP c
V＝K 1e -Q/RT(1-RH)＝V 1(1-RH) (1)
V 1Be the velocity of evaporation of microcosmic, it depends on the character and the temperature of liquid itself.For a kind of liquid, when temperature-resistant a constant.
By above analysis and formula (1) as can be seen, when temperature-resistant, evaporation of water speed V only depends on the relative humidity of the water surface on the per surface area.So according to pascal's principle, the pressure in the water vapor pressure of the water surface and the measuring chamber equates that promptly appropriateness is equal.Water evaporates in measuring chamber realizes by pressure equilibrium, and pressure balance time is extremely short, so velocity of evaporation is very fast.In atmosphere, on the direction from the liquid level to the atmosphere, there is the concentration gradient of water vapour, not therefore can be and the build-up of pressure gradient.So in its space away from liquid level, its humidity is identical with atmospheric humidity, and more near the space of liquid level, its humidity is more near saturated humidity.In atmosphere, the mean free path of water vapour molecule approximately About, to just can be diffused into the atmosphere through ten million collision from the molecule of liquid surface evaporation and to go, stop the suitable time near the space liquid level, therefore near the space liquid level just forms the very high transition bed of humidity.Hydrone is actually a diffusion process by transition bed to the migration of airspace, so water is finished by diffusion process very slowly to the evaporation of atmosphere.By formula (1) as can be seen, though the relative humidity of environment all is RH, because the very high transition bed of a humidity is arranged near the liquid level in atmosphere, this moment, RH approached R CSo velocity of evaporation V is very little.
According to the above-mentioned theory analysis, the applicant has set up cement-based material rapid draing first and has shunk measuring method, and its concrete implementation step is as follows:
1) controls the working temperature of cement-based material test specimen to be measured and the drying shrinkage value that relative humidity is determined this test specimen to be measured by a vacuum measurement chamber that is arranged with the water bath with thermostatic control chuck;
2) by mass change value, change of shape value and temperature change value to definite acquisition test specimen to be measured of relative humidity equilibrium value under the working temperature in the measuring chamber;
Concrete operations are as follows:
A) working temperature of measuring chamber is set, opens between the thermostatted water ebullator of a peripheral hardware and the water bath with thermostatic control chuck and be connected with two pipelines; The thermostatted water ebullator injects in the water bath with thermostatic control chuck by a pipeline wherein can be 10～30 ℃ scope accuracy controlling temperature, error is ± 0.1 ℃ a thermostatted water, thermostatted water flows through in the water bath with thermostatic control chuck again and flows back to the thermostatted water ebullator through another pipeline, thermostatted water circulates in the water bath with thermostatic control chuck temperature in the measuring chamber is ceaselessly heated or cooling processing, make the temperature difference in its measuring chamber be controlled at all the time ± 0.1 ℃ of scope in;
B) open the measuring chamber loam cake, load test specimen to be measured, this test specimen to be measured bottom contacts with a force cell, and the top contacts with a displacement transducer, the attached temperature sensor of outside surface card;
C) sealing measuring chamber top cover, vacuum pump and water pot by peripheral hardware alternately start the air of getting rid of in the measuring chamber, and charge into water vapour, and the standard of deaeration is that the air content in the measuring chamber should be below 2%, vacuum pump and water pot are communicated with measuring chamber respectively by pipeline separately; Wherein, between vacuum pump and pipeline that measuring chamber is communicated with, be provided with vacuum valve; Between water pot and pipeline that measuring chamber is communicated with, be provided with the water pot valve, alternately open or close, the air in the measuring chamber is got rid of by vacuum valve or water pot valve; Demonstrate steam partial pressure P in this measuring chamber by the vacuum meter that is arranged on measuring chamber upper top cover place iValue; By following formula, determine described relative humidity RH; Its formula is:
RH = P i P 0 × 100 %
Wherein: P 0Water saturation vapour pressure when-temperature is t
The surface temperature of the test specimen to be measured that t-is in good time
When temperature t is controlled at 10～30 ℃, calculate saturated vapor pressure P by following formula 0
P 0＝670.76e 0.062t
Wherein: e=2.718.
Working temperature in the above-mentioned measuring chamber is 20 ± 0.1 ℃.
After above-mentioned relative humidity RH determines, force cell described in the step b), displacement transducer and temperature sensor get access to length variations value, mass change value and the temperature change value of this test specimen to be measured on described test specimen to be measured, above-mentioned measurement result is sent into control desk carry out analyzing and processing; Control desk can be set at a computing machine, by computing machine measurement result is carried out analyzing and processing; Also can be designed to hand held console the data that its displacement transducer, force cell and temperature sensor transfer out are carried out hand computation, analysis and processing.
Realize above-mentioned cement-based material rapid draing contraction measuring method, this another technical scheme that provides is provided the special measurement device that is adopted, and its body structure of this cement-based material rapid draing contraction measurement mechanism is as follows.
As shown in Figure 1, it is made control desk, measurement mechanism body 2, vacuum pump 8, water pot 7 by a computing machine 1 and forms with thermostatted water ebullator 9; Measurement mechanism body 2 bottoms are provided with bracing frame 25, and the top is provided with upper cover plate 24, and a vacuum meter 11 is housed on its upper cover plate; Vacuum pump 8, water pot 7 and thermostatted water ebullator 9 be arranged in parallel with bracing frame 25, its vacuum pump 8 and water pot 7 output terminals are communicated with these measurement mechanism body 2 inner chambers in measurement mechanism body 2 bottoms by pipeline break-through separately respectively, pipeline that vacuum pump 8 is connected with its measurement mechanism body 2 middle part is provided with vacuum valve 81, also is provided with a molecular sieve adsorption trap 10 that is used to adsorb steam and oil gas between vacuum pump 8 and the vacuum valve 81; The output terminal of water pot 7 is provided with a threeway, and wherein, a port is communicated with measurement mechanism body 2, and the pipeline middle part of its connection is provided with a water pot valve 71, and another port vertical end upside is equipped with an exhaust and inlet valve 72; Thermostatted water ebullator 9 is communicated with measurement mechanism body 2 sidewalls respectively with a rising pipe by a water inlet pipe, forms a circulation waterway.
The measurement mechanism body 2 that is positioned at bracing frame 25 upsides is that two layers of being provided with base plate and upper cover plate 24 overlap tubulars, the internal layer tube of sleeve is a measuring chamber 22, outer field sleeve is a water bath with thermostatic control chuck 21, and thermostatted water ebullator 9 is communicated with water bath with thermostatic control chuck 21 with the sidewall that rising pipe feeds measurement mechanism body 2 by water inlet pipe; One has the support frame 23 of lower and upper cross-member and two vertical rods, hangs down to being located at measuring chamber 22 centres; At support frame 23 entablature upsides one displacement transducer 3 is installed; Support frame 23 sill upsides are equipped with a force cell 6, leave the position of placing a cement-based material test block 4 to be measured between 3 times contacts of displacement transducer and force cell 6 upper surfaces; Temperature sensor 5 is attached at the vertical rod inboard of support frame one side, temperature sensor 5 ' is attached on the outside surface of cement-based material test block 4 to be measured, and displacement transducer 3, force cell 6, temperature sensor 5,5 ' are connected with the interface of computing machine 1 respectively by line.
Displacement transducer 3 can be selected any in laser displacement sensor, grating displacement sensor or the capacitive displacement transducer for use;
The wallboard of the wallboard of water bath with thermostatic control chuck 21 and measuring chamber 22 all adopts stainless steel or common iron manufacturing.
Vacuum valve 81, water pot valve 71, exhaust and inlet valve 72 can select for use simultaneously the manual shutdown valve of high vacuum, electromagnetism shutdown valve, electromagnetism cut off air release, fine setting needle-valve, manually in air release or the electric current pneumatic valve any, also can select for use different valve combination to use, be used for the indoor water vapor pressure of control survey.
Vacuum meter 11 can be treated the test event requirement of test block according to the client, selects in film vacuum meter, thermocouple vacuum gauge, compound vacuum gauge, ohmer, silicone oil pressure gauge, the mercury manometr any for use.
Computing machine 1 also is connected with vacuum valve 81, water pot valve 71 and vacuum meter 11 respectively by the interface line.The using method of measurement mechanism of the present invention, as shown in Figure 1:
1, working temperature is set: open thermostatted water ebullator 9, in water bath with thermostatic control chuck 21, import recirculated water by water inlet pipe and rising pipe, the water temperature that the thermostatted water ebullator is 9 li can be in 10～30 ℃ of scopes accuracy controlling, its error is ± 0.1 ℃; The inflow water bath with thermostatic control chuck 21 that does not stop by thermostatted water, water in the water bath with thermostatic control chuck 21 is back to again in the thermostatted water ebullator 9 by rising pipe and heats or cooling processing, make the temperature in the measuring chamber 22 be set to the working temperature of regulation, and keep temperature constant state;
2, load test specimen 4 to be measured: test specimen 4 to be measured is packed in the measuring chamber 22, test specimen to be measured 4 lower ends place on the force cell 6, the top joins with displacement transducer 3 contacts that are fixed on support frame 23 crossbeams, a temperature sensor 5 ' is attached at test specimen to be measured 4 surfaces again;
3, the air in the eliminating measuring chamber 22: the upper cover plate 24 of measurement mechanism body 2 is covered, with its measuring chamber 22 sealings, open vacuum pump 8 simultaneously, open vacuum valve 81, close water pot valve 71 and exhaust and inlet valve 72, begin to get rid of the air in the measuring chamber 22, when the air capacity in the measuring chamber 22 2% when following, substantially do not influence the measuring accuracy of cement-based material test specimen to be measured, can think to reach the measurement vacuum state that needs.
4, measure:, just can obtain needed any steam partial pressure P by control valve vacuum valve 81 and water pot valve 71 iValue that is to say, can obtain working temperature, and as 20 ± 0.1 ℃ of following any one required relative humidity RH values, RH through type (1) is tried to achieve:
RH = P i P 0 × 100 % - - - ( 1 )
In the formula
RH---relative humidity;
P i---the partial pressure value of water vapor in the operating room, by regulating vacuum valve, measure gained by vacuum meter;
P 0---water saturation vapour pressure during working temperature t.
Water saturation vapour pressure P 0Can consult from physics frequently-used data table, in the time of 10～30 ℃, also by formula calculate (2):
P 0＝670.76e 0.062t (2)
T---in good time test article surface temperature.
E---get 2.718.
When two temperature sensing actuator temperatures in the measuring chamber reach set point of temperature and error in ± 0.1 ℃, when the force cell displayed value fluctuates in 1%, can think and reach equilibrium state, gather the numerical value of displacement transducer, force cell, temperature sensor, import computing machine, and measurement result is carried out computing, the computing mode adopts conventional method, promptly EXCEL electrical form or the establishment simple computation program by establishing in the computing machine calculates drying shrinkage and mass loss rate.Calculation procedure wherein is according to following formula draw:
ϵ = L 2 - L 1 L 0 × 100 %
ε---drying shrinkage
L 2---the numerical value that displacement transducer is gathered during equilibrium state;
L 1---test specimen has just been put into measuring chamber, the numerical value that displacement transducer is gathered;
L 0---the test specimen datum length does not promptly comprise the length of the cement-based material of gauge head.
w = G 2 - G 1 G 0 × 100 %
W---amount loss rate
G 2---the numerical value that force cell is gathered during equilibrium state;
G 1---test specimen has just been put into measuring chamber, the numerical value that force cell is gathered;
By displacement transducer 3 in the distortion of the indoor measurement of vacuum measurement test specimen to be measured under different relative humidity situations.
By force cell 6 in the mass change of the indoor measurement of vacuum measurement test specimen to be measured under different relative humidity situations.
By temperature sensor 5 ' at the in good time surface temperature t of the indoor measurement of vacuum measurement test specimen to be measured; Be positioned at the indoor temperature variation that the support frame 23 of displacement transducer 3 is housed of vacuum measurement by temperature sensor 5 measurements.Below data by the test specimen actual measured value measuring method of the present invention is further described:
Following table is a cement slurry test specimen, in temperature is that 20 ± 0.1 ℃, relative humidity deviation are under 2% environment, the numerical value that measurement collects is sent into and is carried out analyzing and processing in the computing machine, obtain pairing drying shrinkage of relative humidity RH and mass loss rate, only 7 days time spent, just can gather 10 groups of test figures.
RH/％ Drying shrinkage/% Mass loss/%
100.0 0.00 0.0
90.0 0.12 1.3
80.0 0.20 1.9
70.0 0.27 2.7
60.0 0.33 4.0
50.0 0.38 5.3
40.0 0.43 6.7
30.0 0.47 8.0
20.0 0.51 10.1
10.0 0.55 12.8
0.2 0.59 18.7
Same test specimen, use conventional methods, 180 days times spent, can only measure data under 20 ± 2 ℃ of temperature, relative humidity 60 ± 5% environment, measurement result is a drying shrinkage 0.34%, the experimental result of 4.1%, two kind of method of mass loss is basic identical, but efficient is mutually far short of what is expected with test accuracy.
In like manner, adopt special measurement device of the present invention, measure the cement slurry test specimen, in temperature is 10 ± 0.1 ℃ or under 30 ± 0.1 ℃ condition, all relative humidity deviation can be controlled in 2%, measure to gather and as calculated the machine analysis meter calculate and corresponding drying shrinkage of relative humidity RH and mass loss rate, the same time spent only is 7 days, just can gather 10 groups of test figures.
In sum, adopt measuring method of the present invention and special measurement device test parameter many, the measuring accuracy height can rapid draing shrinkage cement sill, and does not disturb the aquation process of cement, is easy to promotion and implementation.

Claims (9)

1, the dry measuring method of shrinking of a kind of cement-based material is characterized in that it comprises the steps:
1) by a working temperature and a relative humidity that is arranged with the vacuum measurement chamber control cement-based material test specimen to be measured of water bath with thermostatic control chuck, with the drying shrinkage value of this test specimen to be measured of displacement sensor;
2) by mass change value, length variations value and temperature change value to definite acquisition test specimen to be measured of relative humidity equilibrium value under the working temperature in the measuring chamber;
Concrete operations are as follows:
A) working temperature of measuring chamber is set, the thermostatted water ebullator by a peripheral hardware injects thermostatted water in described water bath with thermostatic control chuck, and this thermostatted water circulates in its water bath with thermostatic control chuck;
B) open the measuring chamber loam cake, load described test specimen to be measured, this test specimen to be measured bottom contacts with a force cell, and the top contacts with a displacement transducer, the attached temperature sensor of outside surface card;
C) sealing measuring chamber top cover, vacuum pump and water pot by peripheral hardware alternately start the air of getting rid of in the measuring chamber, and charge into water vapour, and the standard of deaeration is that the air content in the measuring chamber should be below 2%; Demonstrate steam partial pressure P in this measuring chamber by a vacuum meter that probes into measuring chamber iBy following formula, determine described relative humidity RH; Its formula is:
RH = P i P 0 × 100 %
Wherein: P 0Water saturation vapour pressure when-temperature is t
The surface temperature of the test specimen to be measured that t-is in good time
When temperature t is controlled at 10～30 ℃, calculate saturated vapor pressure P by following formula 0
P 0＝670.76e 0.062t
Wherein: e is a constant value, gets 2.718;
After described relative humidity RH determined, the force cell described in the step b), displacement transducer and temperature sensor get access to mass change value, length variations value and the temperature change value of this test specimen to be measured on described test specimen to be measured measurement result was sent into control desk and is carried out analyzing and processing.
2, the dry measuring method of shrinking of cement-based material according to claim 1, it is characterized in that: the described working temperature of step 2 is 20 ± 0.1 ℃; Wherein, the water temperature regulate and control of the described thermostatted water of step a) is at 10～30 ℃, and its error is ± 0.1 ℃.
3, a kind of dry measurement mechanism that shrinks measuring method of above-mentioned cement-based material of realizing, it is characterized in that: it comprises measurement mechanism body, control desk, vacuum pump, water pot and thermostatted water ebullator; Described measurement mechanism body is that two layers of being provided with base plate and upper cover plate overlap tubulars, and its internal layer tube is a measuring chamber, and outer layer sleeve is a water bath with thermostatic control chuck, and vacuum meter is housed on the upper cover plate; One has the support frame of lower and upper cross-member and two vertical rods, hangs down to being located at described measuring chamber middle part; One displacement transducer, it is arranged on described support frame entablature upside; One force cell is installed on described support frame sill upside, leaves a position of placing cement-based material test specimen to be measured under the described displacement transducer between contact and the described force cell upper surface; One temperature sensor is attached at the vertical rod inboard of described support frame one side; Described measurement mechanism body bottom is provided with bracing frame; Described vacuum pump output terminal and described water pot output terminal are communicated with in the base plate of described measurement mechanism body and with this measuring chamber by pipeline break-through separately respectively; Be provided with a vacuum valve between described vacuum pump output terminal and the pipeline that its measurement mechanism body is connected, described water pot output terminal connects a threeway, be provided with a water pot valve between one port and the pipeline that this measurement mechanism body is communicated with, another port vertical end upside is equipped with an exhaust and inlet valve; Be connected with two pipelines between described thermostatted water ebullator and the described water bath with thermostatic control chuck, the rising pipe of described thermostatted water ebullator is communicated with described water bath with thermostatic control chuck with the sidewall that water inlet pipe feeds described measurement mechanism body respectively.
4, measurement mechanism according to claim 3, it is characterized in that: described measuring chamber is sealing vacuum shape, described displacement transducer be in laser displacement sensor, grating displacement sensor or the capacitive displacement transducer any, described vacuum is counted in film vacuum meter, thermocouple vacuum gauge, compound vacuum gauge, ohmer, silicone oil pressure gauge, the mercury manometr any.
5, according to claim 3 or 4 described measurement mechanisms, it is characterized in that: described control desk is collection, analysis, the integrated computing machine of output function software, and it is connected with described vacuum valve, described water pot valve, described displacement transducer, described force cell, described temperature sensor and described vacuum meter respectively by the interface line; Between described vacuum pump and described vacuum valve, be provided with a part sieve adsorption trap.
6, measurement mechanism according to claim 5 is characterized in that: described vacuum valve, described water pot valve and described exhaust and inlet valve be the manual shutdown valve of high vacuum, electromagnetism shutdown valve, electromagnetism cut off air release, fine setting needle-valve, manually in air release or the electric current pneumatic valve any.
7, measurement mechanism according to claim 6 is characterized in that: the wallboard material of described water bath with thermostatic control chuck and the wallboard material of described measuring chamber are a kind of in stainless steel or the common iron.
8, measurement mechanism according to claim 3 is characterized in that: described vacuum valve, water pot valve and described exhaust and inlet valve be the manual shutdown valve of high vacuum, electromagnetism shutdown valve, electromagnetism cut off air release, fine setting needle-valve, manually in air release or the electric current pneumatic valve any.
9, according to claim 3 or 4 or 8 described measurement mechanisms, it is characterized in that: the wallboard material of described water bath with thermostatic control chuck and the wallboard material of described measuring chamber are a kind of in stainless steel or the common iron.
CN200510112560A 2005-10-12 2005-10-12 Method and apparatus for measuring rapid drying shrinkage of cement-based material Expired - Fee Related CN100578221C (en)

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CN200510112560A CN100578221C (en) 2005-10-12 2005-10-12 Method and apparatus for measuring rapid drying shrinkage of cement-based material

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Application Number Priority Date Filing Date Title
CN200510112560A CN100578221C (en) 2005-10-12 2005-10-12 Method and apparatus for measuring rapid drying shrinkage of cement-based material

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CN103472213B (en) * 2013-09-27 2015-03-18 东南大学 Method for measuring strength of cementing materials
CN103713116B (en) * 2013-12-24 2016-07-27 中国建筑材料科学研究总院 A kind of method evaluating high MgO cement stability
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