CN115266519A - Testing device and method for representing water vapor steady-state permeation of cement base material - Google Patents
Testing device and method for representing water vapor steady-state permeation of cement base material Download PDFInfo
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 97
- 239000000463 material Substances 0.000 title claims abstract description 45
- 238000012360 testing method Methods 0.000 title claims abstract description 40
- 239000004568 cement Substances 0.000 title claims abstract description 39
- 238000000034 method Methods 0.000 title claims description 10
- 229920006395 saturated elastomer Polymers 0.000 claims abstract description 74
- 239000012266 salt solution Substances 0.000 claims abstract description 73
- 238000007789 sealing Methods 0.000 claims abstract description 67
- 230000008859 change Effects 0.000 claims abstract description 37
- 230000035699 permeability Effects 0.000 claims abstract description 36
- 229920001971 elastomer Polymers 0.000 claims abstract description 31
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 10
- NLKNQRATVPKPDG-UHFFFAOYSA-M potassium iodide Chemical compound [K+].[I-] NLKNQRATVPKPDG-UHFFFAOYSA-M 0.000 claims description 9
- 229910001868 water Inorganic materials 0.000 claims description 9
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 6
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 claims description 6
- SCVFZCLFOSHCOH-UHFFFAOYSA-M potassium acetate Chemical compound [K+].CC([O-])=O SCVFZCLFOSHCOH-UHFFFAOYSA-M 0.000 claims description 6
- 238000010998 test method Methods 0.000 claims description 6
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 5
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 claims description 4
- XJHCXCQVJFPJIK-UHFFFAOYSA-M caesium fluoride Chemical compound [F-].[Cs+] XJHCXCQVJFPJIK-UHFFFAOYSA-M 0.000 claims description 4
- AMXOYNBUYSYVKV-UHFFFAOYSA-M lithium bromide Chemical compound [Li+].[Br-] AMXOYNBUYSYVKV-UHFFFAOYSA-M 0.000 claims description 4
- JHJLBTNAGRQEKS-UHFFFAOYSA-M sodium bromide Chemical compound [Na+].[Br-] JHJLBTNAGRQEKS-UHFFFAOYSA-M 0.000 claims description 4
- 235000011056 potassium acetate Nutrition 0.000 claims description 3
- 229910001629 magnesium chloride Inorganic materials 0.000 claims description 2
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 claims description 2
- 229910052939 potassium sulfate Inorganic materials 0.000 claims description 2
- 235000011151 potassium sulphates Nutrition 0.000 claims description 2
- 239000011780 sodium chloride Substances 0.000 claims description 2
- 230000005540 biological transmission Effects 0.000 abstract description 16
- 238000005259 measurement Methods 0.000 abstract description 11
- 238000012806 monitoring device Methods 0.000 abstract description 2
- 239000000565 sealant Substances 0.000 abstract 1
- 229940099259 vaseline Drugs 0.000 description 7
- 238000003795 desorption Methods 0.000 description 6
- 239000012153 distilled water Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000009792 diffusion process Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 239000011398 Portland cement Substances 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 238000007667 floating Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 239000008399 tap water Substances 0.000 description 3
- 235000020679 tap water Nutrition 0.000 description 3
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000003292 glue Substances 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 238000002336 sorption--desorption measurement Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- JYYOBHFYCIDXHH-UHFFFAOYSA-N carbonic acid;hydrate Chemical compound O.OC(O)=O JYYOBHFYCIDXHH-UHFFFAOYSA-N 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000001103 potassium chloride Substances 0.000 description 1
- 235000011164 potassium chloride Nutrition 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000000047 product Substances 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/082—Investigating permeability by forcing a fluid through a sample
- G01N15/0826—Investigating permeability by forcing a fluid through a sample and measuring fluid flow rate, i.e. permeation rate or pressure change
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Abstract
The invention belongs to the field of civil engineering, and relates to a testing device and a testing method for representing water vapor steady-state permeation of a cement base material. The testing device comprises an environment unit and a measuring unit, wherein the environment unit comprises a sealing box, and a hygrothermograph is arranged in the sealing box; the measuring unit comprises a cup body, a cup cover is arranged at the upper end of the cup body, a sealing rubber sleeve is arranged on the outer side of the cup cover corresponding to the opening, and scales are arranged on the outer side of the cup body. During measurement, saturated salt solution I is placed in the environment unit, saturated salt solution II is placed in the measurement unit, a sample to be measured is placed in the sealant sleeve, the measurement unit is placed in the environment unit, the whole weight change of the measurement unit is carried out along with the transmission of water vapor, the scale change and the corresponding time of the cup body with the scales are recorded until the scale change and the corresponding time are linear changes, namely the steady-state permeation of the water vapor, and the corresponding permeability can be calculated. The invention develops the cement base material water vapor permeation monitoring device, and has obvious technical and economic benefits and very wide application prospect.
Description
Technical Field
The invention belongs to the field of civil engineering, relates to a cement-based material performance and durability testing technology, and particularly relates to a device and a method for measuring the water vapor permeability of concrete, which are mainly used for representing the water vapor permeability of a cement-based material.
Background
The cement-based material is a typical porous material and is often in an unsaturated state in the actual service process, and the water vapor transmission is an important characteristic of the damp-heat performance of the cement-based material. The water vapor transmission is subjected to phase change conversion, so that the microstructure evolution, the strength development and the service performance of the cement-based material are influenced. And (3) a plasticity stage: the water evaporation can cause early microstructure changes such as shrinkage, cracking and the like of the cement-based material; and (3) a maintenance stage: the proper humidity environment is the guarantee of the strength development of the cement-based material; a service stage: the water vapor transmission determines the water-containing state, and influences the durability of the cement-based material, such as freeze-thaw cycle resistance, ion erosion resistance and the like. Therefore, characterizing water vapor transmission is critical to cement-based material microstructure, strength, service performance, and the like.
According to different transmission power, the water vapor transmission is characterized by diffusion and permeation, and concentration difference and pressure difference are respectively used as driving forces. Currently, water vapor diffusion is performed by isothermal desorption experiments, based on the assumption that (1) water vapor transport is determined by a pure diffusion mechanism, namely: relative to the diffusion flow of water vapor, the laminar flow is ignored and (2) the internal and external air pressures of the material in the transmission process are equal, namely: the total gas (dry air + water vapor) pressure inside the pores remains constant and equal to the external atmospheric pressure. The adsorption-desorption equilibrium state is usually taken as the end point of the experiment, however, the adsorption-desorption equilibrium state is an ideal state and is easily influenced by environmental factors. In comparison, the water vapor permeation takes the air pressure difference as a driving force, the time required by the test is short, the fluid state does not need to be assumed, and the method is more suitable for representing the damp and hot performance of the cement-based material. The permeation of water vapor has not been established on the market at present.
Disclosure of Invention
The invention aims to solve the problems in the prior art, and provides a testing device and a testing method for representing the steady-state permeation of water vapor of a cement-based material, so that the rapid and accurate test of the water vapor permeability of the cement-based material is realized. Aiming at the defects and defects in the existing cement base material water vapor transmission process monitoring technology, the invention creates different humidity environments through saturated salt solution, forms pressure difference on two sides of a sample to drive water vapor permeation transmission, converts the permeation quantity of water vapor in the sample into mass change of the saturated salt solution by combining the physicochemical characteristics of absorption and desorption of the water vapor in the saturated salt solution, carries out real-time monitoring on the mass change by the change of integral buoyancy, and finally realizes the rapid and accurate test of the steady-state permeability of the water vapor of the cement base material.
The technical scheme adopted by the invention for solving the technical problem is as follows:
a testing device for representing water vapor steady-state permeation of a cement-based material comprises an environment unit and a measuring unit, wherein the environment unit comprises a seal box, the seal box comprises a seal box cover and a seal box body, the seal box cover and the seal box body can be connected in a sealing manner, the sealing effect of the seal box is realized, and a hygrothermograph is arranged in the seal box; the measuring unit comprises a cup body, a cup cover is arranged at the upper end of the cup body and connected with the cup cover through a thread structure, an opening is formed in the cup cover, a sealing rubber sleeve is arranged on the outer side of the cup cover corresponding to the opening, the sealing rubber sleeve is communicated with the inner portion of the cup body through the opening in the cup cover, and scales are arranged on the outer side of the cup body. The measuring unit can be arranged in the environment unit, and the environment unit can be sealed, so that the measuring unit is arranged under the environment unit and is not interfered by external factors, and the water vapor permeability of the material is accurately and stably measured.
Preferably, the seal box is a rigid seal box; more preferably the sealed housing is a transparent device, more preferably a transparent glass device or a transparent plastic device. Through adopting the rigidity seal box, can further guarantee the stability of environmental unit, the relevant information of the measuring unit in the environmental unit can be convenient for observe by transparent seal box.
Preferably, the contact surfaces of the sealing box cover and the sealing box body are ground or connected through a threaded structure, so that the sealing performance of the sealing box is further ensured. The sealing of the sealing box can be further enhanced by applying vaseline or the like to the contact surface.
Preferably, the hygrothermograph is arranged at the upper part in the sealed box body.
Preferably, the hygrothermograph is provided with a plurality of, more preferably 3, more preferably uniformly and circumferentially arranged at the upper part in the sealed box body, and more preferably the hygrothermograph is on the same horizontal plane. The temperature and humidity sensor is used for testing temperature and humidity changes in the sealed box.
Preferably, the sealing rubber sleeve has elasticity, is tightly connected with the cup cover to achieve a sealing effect, is detachably connected with the cup cover and can be taken down from the cup cover when needed; can be with the sample that awaits measuring put into behind the sealed gum cover, play the sealed effect of side direction to the sample that awaits measuring to can be used for fixed sample that awaits measuring, so that vapor can not circulate from the side of the sample that awaits measuring, thereby record the vapor permeability of the sample that awaits measuring.
Preferably, the opening is arranged at the central part of the cup cover.
The invention also provides a test method for representing the water vapor steady-state permeation of the cement-based material, which adopts the device and comprises the following steps:
(1) A stable environment unit: saturated salt solution I is filled in the sealing box, the sealing box body and the sealing box cover are sealed, and the sealing box is kept still until the humidity in the sealing box is stable; the humidity change in the sealed box can be recorded by a hygrothermograph arranged in the sealed box;
(2) Placing a measuring unit: placing a saturated salt solution II into the cup body, placing a sample to be measured into a sealing rubber sleeve on the cup cover, connecting the cup cover with the cup body through a thread structure, placing the measuring unit into the environment unit, and making the cup body float on the saturated salt solution I; the saturated salt solution I and the saturated salt solution II are different salt solutions, so that the saturated salt solution I and the saturated salt solution II have different corresponding humidity, and two sides of a sample to be detected are exposed to different humidity environments to realize permeation and transmission of water vapor;
(3) And (3) calculating the permeability: the water vapor is transmitted through the sample to be measured to cause the change of the whole quality of the measuring unit, and the change is converted into the up-and-down floating of the cup body, so that the saturated salt solution I is positioned at different scale positions of the cup body; and recording the scale change and the time of the cup body until the scale change and the time of the cup body linearly change, namely the water vapor steady-state permeation, and calculating the permeability.
Preferably, vaseline is adopted in the step (1) to seal the sealed box body and the sealed box cover. The sealing performance of the sealing box is further enhanced.
Preferably, the saturated salt solution I and the saturated salt solution II in the steps (1) and (2) may be respectively selected from one of cesium fluoride, lithium bromide, lithium chloride, potassium acetate, magnesium chloride, potassium carbonate, sodium bromide, potassium iodide, sodium chloride, potassium sulfate, water and other common saturated salt solutions with standard relative humidity values of approximately from 4% to 100%, and the temperature may be from 5 ℃ to 80 ℃; the saturated salt solution I and the saturated salt solution II are different salt solutions, so that different humidity values of the environment unit and the measurement unit are ensured; more preferably one selected from the group consisting of lithium chloride (11%), potassium acetate (23%), potassium carbonate (43%), potassium iodide (68%), potassium chloride (84%), water (100%), and the parenthesized data are relative humidity values of saturated salt solutions corresponding to temperatures of about 20 ℃ to 25 ℃; it should be noted that the saturated salt solution and the relative humidity can be selected according to the actual conditions and the actual temperature, and are not limited to the data provided by the present invention; more preferably, the relative humidity of the saturated salt solution I is higher than that of the saturated salt solution II, and more preferably, the saturated salt solution I and the saturated salt solution II are water and potassium carbonate which are stable in performance, easy to obtain and cheap, respectively.
Preferably, the distance from the liquid level of the saturated saline solution I to the bottom of the sealing box in the step (1) is not less than the height of the cup body.
Preferably, step (2) in the bowl cover pass through after helicitic texture and cup zonulae occludens, still further glue firmly sealedly through sealed glue to further guarantee the seal box, make vapor only can pass through the sample circulation that awaits measuring.
Preferably, the sample to be tested in the step (2) is cylindrical, the inner diameter of the sample to be tested is 1-2mm larger than that of the sealing rubber sleeve, and the sample to be tested and the sealing rubber sleeve are equal in height. Thereby further guarantee sealed gum cover to the circumferential pressure of the sample that awaits measuring, further play the sealed effect of side direction, prevent that vapor from the side circulation of the sample that awaits measuring.
Preferably, the distance between the liquid level of the saturated saline solution II in the step (2) and the bottom of the sample to be tested is not less than 15 mm.
Preferably, the permeability calculation formula in step (3) is as follows:
in the formula: delta-water vapor permeability of concrete in kg.m-1·s-1·Pa-1；
P1And P2The saturated salt solution I and the saturated salt solution II form a water vapor pressure in Pa corresponding to different humidities, more preferably in relation to the relative humidity (RH,%) and the temperature (T, ° C), which can be calculated according to the following formula
Rho-density of saturated salt solution I in kg/m3；
d and A-height (m) and Cross-sectional area (m) of the cylindrical sample2)；
(l1-l2) -the scale change in Δ t time in m;
s-the external section area of the cup body (2-5) with scales is m2。
The invention provides a testing device for water vapor steady-state permeation of a cement-based material, which is divided into an environment unit and a measuring unit, wherein the environment unit comprises: the system comprises a rigid seal box, a hygrothermograph and a saturated salt solution I, wherein an environment unit forms an external environment with a certain temperature and humidity; the measuring unit includes: the measuring unit comprises a sample, a sealing rubber sleeve, a cup cover, a saturated salt solution II and a cup body with scales, and a certain temperature-humidity internal environment is formed inside the measuring unit. After the measuring unit is arranged in the environment unit, the measuring unit can be still on the water surface of the saturated salt solution I of the environment unit due to self buoyancy, the whole weight of the measuring unit changes along with the transmission of water vapor, the scale change and the corresponding time of the cup body with the scales are recorded until the scale change and the corresponding time are linear changes, namely the steady state permeation of the water vapor, and the corresponding permeability is calculated. The water vapor permeation and transmission are realized by forming pressure difference in the two systems, the physical and chemical properties of absorption and desorption of water vapor in saturated salt solution change the whole mass of the measuring unit, the timely measurement is realized by buoyancy, and the change rate is the steady-state permeation flow of the water vapor in the cement-based material.
Firstly, different saturated salt solutions are adopted to respectively create certain humidity environments on two sides of a cement-based material, and pressure difference formed by different humidities drives water vapor to permeate in the material; generally, a saturated salt solution in a measuring unit is selected to create a low-pressure end, a saturated salt solution in an environment unit creates a high-pressure end, the collection of water vapor is realized through the adsorption of the water vapor at the low-pressure end in the saturated salt solution, the mass of the measuring unit after the water vapor is collected is increased, the measuring unit sinks on the liquid level of the environment unit, and the water vapor mass of a permeable material is obtained by combining buoyancy and adopting a drainage method; and finally, deriving a permeability expression of water vapor in the cement-based material based on a seepage mechanics theory and an ideal gas law for quantitative calculation.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention adopts different saturated salt solutions to form a steam pressure difference on two sides of the sample to be tested, and adopts a rubber sleeve confining pressure mode to seal the sample to be tested, thereby realizing the axial permeation and transmission of the steam. According to the invention, different saturated salt solutions are adopted on two sides of the sample to create corresponding humidity environments, different water vapor corresponds to different gas pressures, and the water vapor performs permeation transmission under the action of pressure difference to perform confining pressure sealing on the sample, so that the axial permeation of the water vapor is realized.
2. The method is based on the physicochemical characteristics of saturated salt solution on water vapor adsorption and desorption, and realizes the test of the water vapor flow in the sample by combining the relationship between the mass and the buoyancy. According to the invention, different saturated salt solutions are respectively arranged in the environment unit and the measurement unit to create corresponding humidity environments, high-humidity water vapor flows to the low-humidity environment through the sample and is absorbed by the low-humidity saturated salt solution, the change of the mass in the measurement unit is measured through the change of the buoyancy of the measurement unit, the timely and accurate acquisition of the water vapor flow is realized, and the water vapor permeability of the material is further calculated.
3. The invention comprehensively applies the physical and chemical properties of water vapor and the absorption-desorption effect and the drainage method of saturated salt solution, solves the problem of quantitative characterization of water vapor permeation of cement-based materials, develops a water vapor permeation monitoring device for cement-based materials, has no products at home and abroad, has obvious technical and economic benefits and has very wide application prospect.
Drawings
FIG. 1 is a schematic perspective view of a testing device according to the present invention;
in the figure, a seal box 1-1, a hygrothermograph 1-2, a saturated salt solution I1-3, a sample to be tested 2-1, a seal gum cover 2-2, a cup cover 2-3, a saturated salt solution II 2-4 and a cup body 2-5,
FIG. 2 is a schematic diagram illustrating the testing principle of the testing method according to the present invention;
FIG. 3 specific results of example 1 carried out using the apparatus of the invention;
FIG. 4 specific results of example 2 carried out using the apparatus of the invention;
FIG. 5 shows the specific results of example 3 carried out using the apparatus of the invention.
Detailed Description
The technical solution of the present invention is further specifically described below by using specific embodiments and with reference to the accompanying drawings.
The invention provides a testing device for representing the steady-state permeation of water vapor of a cement-based material, which is divided into an environment unit and a measuring unit, wherein the environment unit comprises: the system comprises a rigid seal box 1-1, a hygrothermograph 1-2 and a saturated salt solution I1-3, wherein an environment unit forms a temperature and humidity external environment; the measuring unit includes: 2-1 parts of a sample to be measured, 2-2 parts of a sealing rubber sleeve, 2-3 parts of a cup cover, 2-4 parts of a saturated salt solution and 2-5 parts of a cup body with scales, and a temperature and humidity internal environment is formed inside the measuring unit. The two systems realize water vapor permeation and transmission due to pressure difference formed by different environments, the physical and chemical characteristics of absorption-desorption of water vapor in saturated salt solution change the overall mass of the measuring unit, the real-time measurement is realized through buoyancy, and the change rate of the change rate is the steady-state permeation flow of the water vapor in the cement-based material.
Specifically, the testing device comprises an environment unit and a measuring unit, the environment unit comprises a seal box 1-1, the seal box 1-1 comprises a seal box cover and a seal box body, the seal box cover and the seal box body can be connected in a sealing mode to achieve the sealing effect of the seal box, and a hygrothermograph 1-2 is arranged inside the seal box 1-1; the measuring unit comprises a cup body 2-5, a cup cover 2-3 is arranged at the upper end of the cup body 2-5, the cup body 2-5 is connected with the cup cover 2-3 through a threaded structure, an opening is formed in the cup cover 2-3, a sealing rubber sleeve 2-2 is arranged on the outer side of the cup cover corresponding to the opening, the sealing rubber sleeve 2-2 is communicated with the inner portion of the cup body 2-5 through the opening in the cup cover 2-3, and scales are arranged on the outer side of the cup body 2-5. The measuring unit can be arranged in the environment unit, and the environment unit can be sealed, so that the measuring unit is arranged under the environment unit and is not interfered by external factors, and the water vapor permeability of the material is accurately and stably measured.
The sealing box 1-1 is a rigid transparent sealing box, so that the stability of the sealing box is ensured, and the relevant information of a measuring unit in an environment unit is convenient to observe; the contact surfaces of the sealing box cover and the sealing box body of the sealing box are ground or connected through a thread structure, and meanwhile, the sealing performance of the sealing box is further enhanced by coating vaseline;
the hygrothermographs 1-2 are arranged above the liquid level of the saturated salt solution I in the sealed box body and are used for detecting the temperature and the humidity in an environment system;
the sealing rubber sleeve 2-2 has certain elasticity, the more preferable sealing rubber sleeve is cylindrical, the diameter of the sealing rubber sleeve is 1-2cm smaller than that of a cylindrical sample to be measured 2-1, the height of the sealing rubber sleeve 2-2 is equal to that of the sample to be measured 2-1, so that the sample to be measured can be filled into the sealing rubber sleeve under the elasticity, and meanwhile, the sealing rubber sleeve forms confining pressure on the periphery of the sample to be measured under the action of the elasticity, so that water vapor can only flow in the axial direction of the sample to be measured and cannot flow from the side edge during measurement; the more preferable opening on the cup cover 2-3 is arranged at the central part, so that the water vapor can uniformly enter and exit the central part, the uniform mass change is realized in the measuring unit, and the phenomenon that the cup body 2-5 is inclined due to the uneven mass change and the center-of-gravity shift is further avoided, so that the scale reading is influenced.
The measuring method comprises the following steps: firstly, a proper amount of saturated salt solution I1-3 is put into a rigid seal box 1-1, a box cover and a box body of the rigid seal box 1-1 are sealed by Vaseline, meanwhile, a hygrothermograph 1-2 is put into different positions to record the humidity change in the rigid seal box 1-1, and the rigid seal box is kept stand for a period of time until the humidity in the box is stable.
Then, a cylindrical cement-based material sample 2-1 is placed in a sealing rubber sleeve 2-2, the sealing rubber sleeve 2-2 is tightly connected with a cup cover 2-3, and a hole in the center of the cup cover 2-3 is equal to the diameter of the sample 2-1 and is integrated with the sealing rubber sleeve 2-2. During testing, a proper amount of saturated salt solution II 2-4 is placed in the graduated cup body 2-5, the cup cover 2-3 and the graduated cup body 2-5 are tightly screwed and tightly sealed and adhered, and the whole measuring unit is placed in an environment unit.
And finally, the measuring unit can be still on the water surface of the saturated salt solution I1-3 of the environment unit due to the buoyancy of the measuring unit, the scale change and the corresponding time of the cup body 2-5 with the scale are recorded until the scale change and the corresponding time are linear changes, namely the water vapor steady-state permeation is obtained, and the corresponding permeability is calculated.
The technical solution of the present invention is further described in detail by the following specific examples.
Example 1:
P.I. 52.5 portland cement and tap water are adopted. Mixing ratio (kg/m)3): cement-433.0, sand-655.0, coarse aggregate (5 mm-20 mm) -1117, water-195 and additive-2.20.
And (4) forming a concrete sample (CR 45) according to the mixing proportion, and performing standard curing for 90d. Before the test, a cylindrical sample with the diameter of 50mm and the height of 50mm is drilled and dried to constant weight at 105 ℃. Before testing, firstly, a proper amount of distilled water (corresponding to 100% relative humidity under the special condition of saturated salt solution I) is put into a rigid sealed box, the box cover and the box body of the rigid sealed box are sealed by Vaseline, simultaneously, hygrothermographs are put into different positions to record the humidity change in the rigid sealed box, and the rigid sealed box is kept stand for a period of time until the humidity in the rigid sealed box is stable.
Then, a proper amount of saturated K is put into the cup body with the scale2CO3(saturated salt solution II, corresponding to a relative humidity of 43%,23 ℃), placing a cylindrical sample in a sealing rubber sleeve with an inner diameter of 48mm, tightly connecting the cylindrical sample with a cup cover, tightly screwing the cup cover and a cup body with scales, and placing the whole body in a rigid sealThe box was floated in distilled water and the initial position of the graduation mark was recorded (l)1) (ii) a And finally, recording the scale change and the corresponding time of the cup body with the scale every 1 day until the scale changes linearly with the corresponding time, namely the water vapor steady-state permeation, and calculating the corresponding permeability, wherein the test result is shown in fig. 3. The parameters involved are as follows: the respective temperatures T of the two systems are obtained by a hygrothermograph (1-2) (generally considered to be the same), scale readings on the outer side of the cup body (2-5) in the test piece and corresponding time (directly read at any time) are substituted into a calculation formula by combining parameters of the height and the sectional area of the cylindrical sample and the outer sectional area of the cup body (2-5) to calculate the permeability delta.
The permeability calculation formula is as follows:
in the formula: delta-concrete water vapor permeability in kg. M-1·s-1·Pa-1；
P1And P2The saturated salt solution I and the saturated salt solution II form a water vapor pressure in Pa corresponding to different humidities, more preferably Relative Humidity (RH) and temperature (T), which can be calculated according to the following formula
In this example, T was 23 ℃, RH of saturated salt solution I water was 100%, RH of saturated salt solution II potassium carbonate was 43%, and P was obtained1＝2.81×103Pa，P2＝1.21×103Pa；
Rho-density of saturated salt solution I in kg/m3(ii) a In the present example, ρ =1000kg/m3；
d and A-height (m) and Cross-sectional area (m) of the cylindrical sample2) (ii) a In this example, d =0.05m, a =1.96 × 10- 3m2；
(l1-l2) -the scale changes in Δ t time in units of m; in this example, t1＝1.0×106s, at this time l1＝4.01mm，t2＝6.0×106s, at this time l2＝4.26mm，△t＝5.0×106s，l1-l2＝0.25mm；
S-area of outer section of cup body (2-5) with scale, unit is m2(ii) a In this example, S is 5.41X 10-3m2；
The corresponding data are substituted into the formula, and the permeability delta =4.25 × 10 measured in the embodiment is obtained by combining the data with the graph of fig. 3-12kg·m-1·s-1·Pa-1。
Example 2:
based on sample CR45 of example 1, coarse aggregate was removed to obtain sample MR45, and P.I. 52.5 portland cement and tap water were used. The mixing ratio (kg): cement-433.0, sand-655.0, water-195 and additive-0.5
And (5) forming a concrete sample (MR 45) according to the mixing proportion, and performing standard curing for 90d. Before the test, a cylindrical sample with the diameter of 50mm and the height of 50mm is drilled and dried to constant weight at 105 ℃. Before testing, firstly, a proper amount of distilled water (corresponding to 100% relative humidity under the special condition of saturated salt solution I) is put into a rigid sealed box, the box cover and the box body of the rigid sealed box are sealed by Vaseline, simultaneously, hygrothermographs are put into different positions to record the humidity change in the rigid sealed box, and the rigid sealed box is kept stand for a period of time until the humidity in the rigid sealed box is stable. Then, a proper amount of saturated KCO is put into the cup body with the scale3(saturated salt solution II, corresponding to a relative humidity of 43%,23 ℃), placing a cylindrical sample in a sealed rubber sleeve with an inner diameter of 48mm, tightly connecting the cylindrical sample with a cup cover, tightly screwing the cup cover and a cup body with scales, placing the whole in a rigid sealed box, floating in distilled water, and recording the initial position of a scale mark (l)1) (ii) a And finally, recording the scale change and the corresponding time of the cup body with the scales every 1 day until the scales and the corresponding time are linearly changed, namely the water vapor steady-state permeation, and calculating the corresponding permeability, wherein the test result is shown in fig. 4. The parameters involved are as follows: the respective temperatures T of the two systems are obtained by a hygrothermograph (1-2) (generally considered to be the same), the scale index and the corresponding time (directly read at any time) are arranged on the outer side of a cup body (2-5) in the test piece, and the height of the cylindrical test sample is combinedSubstituting the parameters of the degree, the sectional area and the external sectional area of the cup body (2-5) into a calculation formula to calculate the permeability delta.
The permeability calculation formula is shown in example 1, wherein in the present example, t is1＝1.0×106s, at this time l1＝3.71mm，t2＝6.0×106s, at this time l2＝4.05mm，△t＝5.0×106s，l1-l2=0.34mm, the remaining parameters being the same as in example 1; with reference to fig. 4, the permeability δ =5.87 × 10 measured in this example was obtained-12kg·m-1·s-1·Pa-1。
Example 3:
based on sample MR45 of example 2, fine aggregate was removed to obtain sample PR45, and Portland cement P.I. 52.5 and tap water were used. Mixing proportion (kg): cement-433.0, water-195
And (5) forming a concrete sample (PR 45) according to the mixing proportion, and carrying out standard curing for 90d. Before the test, a cylindrical sample with the diameter of 50mm and the height of 50mm is drilled and dried to constant weight at 105 ℃. Before testing, firstly, a proper amount of distilled water (corresponding to 100% relative humidity under the special condition of saturated salt solution I) is put into a rigid sealed box, the box cover and the box body of the rigid sealed box are sealed by Vaseline, simultaneously, hygrothermographs are put into different positions to record the humidity change in the rigid sealed box, and the rigid sealed box is kept stand for a period of time until the humidity in the rigid sealed box is stable. Then, a proper amount of saturated K is put into the cup body with the scale2CO3(saturated salt solution II, corresponding to a relative humidity of 43%,23 ℃), using a sealed rubber sleeve with an inner diameter of 48mm, placing a cylindrical sample in the sealed rubber sleeve and tightly connecting the cylindrical sample with a cup cover, tightly screwing the cup cover and a cup body with scales, placing the whole in a rigid sealed box and floating in distilled water, and recording the initial position (l) of a scale mark1) (ii) a And finally, recording the scale change and the corresponding time of the cup body with the scales every 1 day until the scales and the corresponding time are linearly changed, namely the water vapor steady-state permeation, and calculating the corresponding permeability, wherein the test result is shown in fig. 5. The parameters involved are as follows: the respective temperatures T of the two systems are obtained by a hygrothermograph (1-2) (generally considered to be the same), and the scale numbers and the corresponding time (direct and direct at any time) are displayed on the outer sides of the cup bodies (2-5) in the test pieceReading) and substituting parameters of the height and the sectional area of the cylindrical sample and the external sectional area of the cup body (2-5) into a calculation formula to calculate the permeability delta.
See example 1 for the permeability calculation formula, where t1＝1.0×106s, at this time l1＝2.63mm，t2＝6.0×106s, at this time l2＝3.28mm，△t＝5.0×106s，l1-l2=0.65mm, and the other parameters are the same as in example 1; with reference to fig. 5, the permeability δ =11.07 × 10 measured in the present example was obtained-12kg·m-1·s-1·Pa-1。
The above-described embodiments are merely preferred embodiments of the present invention, which is not intended to be limiting in any way, and other variations and modifications are possible without departing from the scope of the invention as set forth in the appended claims.
Claims (10)
1. The testing device for representing the water vapor steady-state permeation of the cement-based material is characterized by comprising an environment unit and a measuring unit, wherein the environment unit comprises a sealing box (1-1), the sealing box (1-1) comprises a sealing box cover and a sealing box body, and a hygrothermograph (1-2) is arranged in the sealing box (1-1); the measuring unit comprises a cup body (2-5), a cup cover (2-3) is arranged at the upper end of the cup body (2-5), the cup body (2-5) is connected with the cup cover (2-3) through a threaded structure, an opening is formed in the cup cover (2-3), a sealing rubber sleeve (2-2) is arranged on the outer side of the cup cover corresponding to the opening, and scales are arranged on the outer side of the cup body (2-5).
2. The test device for characterizing the water vapor steady-state permeation of the cement-based material is characterized in that the seal box (1-1) is a rigid seal box, and the seal box body is a transparent device.
3. The test device for characterizing the water vapor steady-state permeation of the cement-based material is characterized in that the hygrothermograph (1-2) is arranged at the upper part in the sealed box body.
4. The testing device for characterizing the water vapor steady-state permeation of the cement-based material is characterized in that the sealing rubber sleeve (2-2) has elasticity, and the sealing rubber sleeve (2-2) is tightly connected with the cup cover (2-3).
5. The testing device for characterizing the water vapor steady-state permeation of the cement-based material as claimed in claim 1, wherein the opening is disposed at a central portion of the cup cover (2-3).
6. A test method for characterizing the steady state water vapor permeation of a cement-based material, wherein the method employs the test device of any one of claims 1 to 5, comprising the steps of:
(1) A stable environment unit: saturated salt solution I is filled in the sealing box, the sealing box body and the sealing box cover are sealed, and the sealing box is kept still until the humidity in the sealing box is stable;
(2) Placing a measuring unit: placing a saturated salt solution II into the cup body, placing a sample to be measured into a sealing rubber sleeve on the cup cover, connecting the cup cover with the cup body through a thread structure, placing the measuring unit into the environment unit, and making the cup body float on the saturated salt solution I;
(3) And (3) calculating the permeability: and recording the scale change and the time of the cup body until the scale change and the time of the cup body are linearly changed, namely the water vapor steady-state permeation, and calculating the permeability.
7. The test method for characterizing the steady water vapor permeability of the cement-based material according to claim 6, wherein the saturated salt solution I and the saturated salt solution II in the steps (1) and (2) are respectively selected from one of cesium fluoride, lithium bromide, lithium chloride, potassium acetate, magnesium chloride, potassium carbonate, sodium bromide, potassium iodide, sodium chloride, potassium sulfate and water.
8. The test method for characterizing the water vapor steady-state permeability of a cement-based material as claimed in claim 7, wherein the humidity of the saturated salt solution I is higher than that of the saturated salt solution II.
9. The test method for characterizing the steady-state water vapor permeation of the cement-based material according to claim 6, wherein the sample to be tested in the step (2) is cylindrical, the inner diameter of the sample is 1-2mm larger than that of the sealing rubber sleeve, and the sample to be tested is equal to the sealing rubber sleeve in height.
10. The test method for characterizing the water vapor steady-state permeability of the cement-based material as claimed in claim 6, wherein the permeability in step (3) is calculated by the following formula:
in the formula: delta-concrete water vapor permeability in kg. M-1·s-1·Pa-1；
P1And P2The saturated salt solution I and the saturated salt solution II form a water vapor pressure in Pa corresponding to different humidities, more preferably Relative Humidity (RH) and temperature (T), which can be calculated according to the following formula
Rho-density of saturated salt solution I in kg/m3；
d and A-height (m) and Cross-sectional area (m) of the cylindrical sample2)；
(l1-l2) -the scale change in Δ t time in m;
s-the external section area of the cup body (2-5) with scales is m2。
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