CN1815175A - Detecting instrument for concrete gas seepage coefficient under single-shaft-pressure stress and detecting method - Google Patents
Detecting instrument for concrete gas seepage coefficient under single-shaft-pressure stress and detecting method Download PDFInfo
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- CN1815175A CN1815175A CNA2006100237629A CN200610023762A CN1815175A CN 1815175 A CN1815175 A CN 1815175A CN A2006100237629 A CNA2006100237629 A CN A2006100237629A CN 200610023762 A CN200610023762 A CN 200610023762A CN 1815175 A CN1815175 A CN 1815175A
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Abstract
Said invention refers to concrete gaseous permeability coefficient uniaxial compressive stress tester and testing method belonging to concrete material viability detection technique field. It contains dying, dying sample room, supporting frame, lifting jack, pressurizing plate, compressed gas tank, and pressure gauge etc, wherein dying consisting of dying cover board and dying bottom case, dying sample room located in dying bottom case, dying cover board and dying bottom case respectively set with outgoing gas chamber, intake chamber in turn connected with inlet valve, compressed gas, and pressure gauge, lifting jack and pressurizing respectively located at two ends of test sample, one side of dying bottom case set leakage check groove. In testing, tested sample is located in dying sample room, pressing in wedge, screwing dying, checking leak tightness, starting up lifting jack, applying compressive stress in test sample, opening compressed gas tank valve, keeping tested sample equilibration time being 10-20 minute, each tested sample repeating testing gas permeation time by more than 3-5 times, changing test pressure and repeat testing, to obtain tested sample permeability coefficient average value, taking 3-5 tested sample permeability coefficient average value as test value of said group tested sample. Said invention has easy and simple to handle, reliable test result, assembly type unit, and convenient for carrying.
Description
Technical field
The invention belongs to concrete material permanance detection technique field, be specifically related to a kind of detecting instrument for concrete gas seepage coefficient under single-shaft-pressure stress and method of testing thereof.
Background technology
Concrete must work in the state of certain load action as building structural materials, existing testing tool all can only be tested the performance of concrete under unstress state, and the instrument that development can be tested concrete performance index under stress is the common objective of academia and engineering circle.
At present, be the infiltration coefficient method of testing of tested media with gas, mainly contain Figg method and Cembureau method.
The Figg method is measured the method that concrete density belongs to half breakage, bore the aperture of a 10mm at concrete surface, the about 40mm of the degree of depth, to squeeze into a rubbery stopper of being close to hole wall after the floating ash removing in the hole, form the zone of a sealing in the bottom in hole, put on a small needle tube again at the center of rubber plug, the vacuum pump of the external band valve of this needle tubing, during experiment sealing area is vacuumized, absolute pressure value in the zone is less than 0.45MPa, close vacuum pump, because the leakage of concrete micropore, vacuum tightness will progressively reduce in time, and the index of its measurement is that the absolute pressure in the sealing area changes to the time that 0.50MPa will spend from 0.45MPa, and unit is second.The method equipment needed thereby is simple and easy, but sealing effectiveness is undesirable.The repeatability of test findings and reliability are subjected to the query of academia.
1989, Kollek proposed with O
2Cembureau method for permeating medium mensuration concrete infiltration coefficient obtains international accepting extensively.Its principle is: apply stable air pressure to sample, be recorded under this pressure by the gas flow of sample, be transformed into infiltration coefficient again, with this concrete permeability energy relatively.This method has adopted the hermetically-sealed construction of rubber-tyred, and sealing effectiveness is very desirable.Its test procedure strictness, the test procedure complexity.But the test experiments operation is too loaded down with trivial details, and equipment needed thereby is huge, and the loading and unloading of tested sample are hard.
Therefore, research is a kind of can test the instrument of the concrete gas infiltration coefficient when action of compressive stress and the goal in research that method of testing is those skilled in the art.
Summary of the invention
The objective of the invention is to propose a kind of easy and simple to handle, reliable test result, portable detecting instrument for concrete gas seepage coefficient under single-shaft-pressure stress and method of testing thereof.
The detecting instrument for concrete gas seepage coefficient under single-shaft-pressure stress that the present invention proposes is by mould, mould sample chamber 8, support 11, lifting jack 12, increased pressure board 13, compression gas tank 14, pressure gauge 15 be connected flexible pipe 16 etc. and form (its structure as shown in Figure 1-Figure 3).Mould is connected by bolt 7 with mould drain pan 2 by die cover plate 1, mould sample chamber 8 is positioned at mould drain pan 2, be used to place concrete sample, die cover plate 1 is provided with discharge chamber 9, correspondingly, mould drain pan 2 is provided with inlet plenum 10, and inlet plenum 10 and gas admittance valve 5 are by being threaded, and gas admittance valve 5 connects compression gas tank 14, pressure gauge 15 respectively by connecting flexible pipe 16; Lifting jack 12 is fixed on the support base plate 18, and the oil cylinder of lifting jack 12 top links to each other with mould drain pan 2, and increased pressure board 13 1 ends are fixed in rack plate 17 bottoms, and the other end connects die cover plate 1; Mould drain pan 2 two sides are provided with leakage check groove 6, are used to check sealing effectiveness.
Among the present invention, place mould sample chamber 8 inner concrete samples to be provided with sealing gasket 3 perpendicular to two planes of gas flow direction.
Among the present invention, place the side of mould sample chamber 8 inner concrete samples to be provided with press seal wedge 4, to guarantee the sealing of detected concrete sample side.
Among the present invention, the profile that places mould sample chamber 8 inner concrete samples of surveying is a hexahedron, and its length is 70.7～150mm, and width is 70.7～150mm, and thick is 40～70mm.
Among the present invention, described sealing gasket 3 is quadrilateral, and its middle part has circular hole.
The method of testing of concrete gas permeability coefficient tester under the uniaxial compressive stress effect that the present invention proposes, concrete steps are as follows:
(1) reach the concrete sample in regulation length of time and dry under 50 ℃～65 ℃ conditions, the outside surface of concrete sample adopts encapsulation process, and the sample of handling well places drying basin, at room temperature leaves standstill 36～54 hours;
(2) tested sample that obtains in the step (1) is placed testing mould, be pressed into chock, tighten mould, check sealing condition by leakage check groove 6, till air tight, start lifting jack, apply compressive stress on tested sample, pressure effect to this sample testing finishes, and opens compression gas tank, air pressure is transferred to the force value of appointment, keeping the equilibration time of tested sample is 10～20 minutes, so that may be by all being full of the gas that is seen through in the passage of gas, closes compression gas pot valve in the tested sample, the ventilative time of test in the fixed pressure drop segment limit, record should be breathed freely the time; Each tested sample repeats to survey the ventilative time 3-5 time, requires the extreme difference of three data to be not more than 2 seconds;
(3) change the compressive stress that lifting jack applies, repeat above test, test sees through the ventilative time of tested sample, tries to achieve tested sample infiltration coefficient mean value, gets the test value of 3～5 tested sample infiltration coefficient mean values as this group tested sample; Wherein the infiltration coefficient of tested sample calculates by following formula:
In the formula: D---concrete gas infiltration coefficient (m
2),
P
a---local atmospheric pressure (Pa),
P
1, P
2---initial, the termination force value (Pa) of fixed pressure drop section,
Q---gas flow (m
3/ s),
The thickness of L---sample (m),
μ---aerodynamic force viscosity (Pas),
A---the sectional area (m that breathes freely in the sample
2),
The ventilative time (s) of t---measurement,
R---gas universal constant,
T---environment temperature during test (℃),
Volume (the m in V---confined gas chamber
3).
Among the present invention, the gas medium in the described compression gas tank is O
2, N
2, air or CO
2Deng.
Among the present invention, the fixed pressure drop section variation range in the described step (2) is 0.05MPa～0.2MPa.
Through a large amount of experimental studies, apparatus of the present invention are easy and simple to handle, reliable test result.But instrument is an assembled, is easy to carry.The present invention is in conjunction with the relevant national standard of China, the test problem of the concrete gas infiltration coefficient when having solved action of compressive stress.Its test philosophy builds on the Darcy's law, and concrete gas infiltration coefficient computation model is simple, and its test form is original creation.
Description of drawings
Fig. 1 is a mould spatial structure diagram of the present invention.
Fig. 2 is the central cross-sectional view of Fig. 1.
Fig. 3 is a structural representation of the present invention.
Fig. 4 is the structural representation of sealing gasket of the present invention.
Number in the figure: 1 is die cover plate, and 2 is the mould drain pan, and 3 is sealing gasket, 4 is the press seal wedge, and 5 is gas admittance valve, and 6 are the leakage check groove, 7 is bolt, and 8 is the sample chamber, and 9 is discharge chamber, 10 is inlet plenum, and 11 is support, and 12 is lifting jack, 13 for acting on the increased pressure board of sample, and 14 is compression gas tank, and 15 is pressure gauge, 16 for connecting flexible pipe, and 17 is rack plate, and 18 is the support base plate.
Embodiment
The invention is further illustrated by the following examples.
Embodiment 1: following each parts are connected by mode shown in Fig. 1,2, and the person skilled in art all can smooth implementation.Die cover plate 1 adopts the A3 steel, and it is of a size of long 130mm, wide 90mm, thick 30mm; Discharge chamber 9 diameters are that 50mm, the degree of depth are 18mm; Mould drain pan 2 adopts the A3 steel, and it is of a size of long 90mm, wide 90mm, thick 75mm; Inlet plenum 10 diameters are that 50mm, the degree of depth are 18mm; Leakage check groove 6 width are 4mm, the long 70mm of being; The detected concrete specimen size is 70.7mm * 70.7mm * 40mm; Air intake valve 5 models are DN10; Compression gas tank 14 is the industrial nitrogen steel cylinder; Flexible pipe 16 is the vacuum rubber pipe; Pressure gauge 15 is a mercury U type measuring cell; Lifting jack 12 is hydraulic type 20t; Sealing gasket 3 adopts the thick vacuum rubber sealing gasket of 3mm.
Embodiment 2: method of testing
Press table 1 match ratio moulding sample, concrete sample is of a size of 70.7mm * 70.7mm * 40mm, and the test gas medium adopts nitrogen.
The above-mentioned concrete sample that will reach the 28 day length of time is 55 ± 2 ℃ of oven dry, paste the thick vacuum rubber sealing gasket of 2mm on four sides along thickness direction, pasting thickness at two faces of ventilative direction is the vacuum rubber sealing gasket of 3mm, cementing agent can adopt silicon rubber, encapsulation process is made with thick white paint or silicone adhesive in all edges and corners of concrete sample, and the sample of handling well is put into drying basin and at room temperature left standstill 48 hours.Concrete sample after handling well places in the mould, be pressed into side press seal wedge, tighten the attaching nut on the mould, again mould is placed on the lifting jack in the support, closely connected rack plate and at the end, put the very heavy required pressure that peaks at, open compression gas tank then, air pressure is transferred to the force value of appointment, kept the interior duration of ventilation of sample 20 minutes, the closes compression gas tank begins to test the ventilative time in 0.15MPa～0.144MPa pressure drop segment limit, and record should be breathed freely the time; Change the pressure that requires of lifting jack, repeat above test, write down the test value of various conditions, press
Try to achieve sample infiltration coefficient value, get the test value of three sample infiltration coefficient mean values as this group tested sample; Test result sees Table 2.
Table 1 experiment concrete mix
| Numbering | Proportioning/(kg/m 3) | Water cement ratio | f c，28d /MPa | |||
| 425 ordinary portland cements | Water | Medium sand | 5～25 rubbles | |||
| A1 A2 A3 | 365 365 365 | 190 201 212 | 609 675 691 | 1236 1150 1129 | 0.52 0.55 0.58 | 45.4 42.6 39.4 |
Table 2 infiltration coefficient result of calculation summary sheet
| Curing age | Lifting jack working stress ratio | 0.00 | 0.20 | 0.30 | 0.39 | 0.42 | 0.46 | 0.50 | 0.53 | 0.57 |
| The proportioning numbering | Infiltration coefficient * 10 17/m 2 | |||||||||
| 28d 28d 28d | A1 A2 A3 | 7.31 7.97 13.54 | 7.51 8.35 13.25 | 7.51 8.90 14.19 | 7.40 9.29 16.04 | 7.71 9.37 118.43 | 8.09 11.71 193.2 | 10.24 253.2 | 10.57 | 188.3 |
Wherein, the lifting jack working stress is than being defined as actual stress and the 28 days compressive strength (f in the table 1 of this sample that puts on test block of lifting jack
C, 28d) the ratio.
Claims (9)
1, detecting instrument for concrete gas seepage coefficient under single-shaft-pressure stress, by mould, mould sample chamber (8), support (11), lifting jack (12), increased pressure board (13), compression gas tank (14), pressure gauge (15) be connected flexible pipe (16) and form, it is characterized in that mould is connected by bolt (7) with mould drain pan (2) by die cover plate (1), mould sample chamber (8) is positioned at mould drain pan (2), concrete sample is positioned at mould sample chamber (8), die cover plate (1) is provided with discharge chamber (9), correspondingly, mould drain pan (2) is provided with inlet plenum (10), inlet plenum (10) and gas admittance valve (5) are by being threaded, and gas admittance valve (5) connects compression gas tank (14) respectively by connecting flexible pipe (16), pressure gauge (15); Lifting jack (12) is fixed on the support base plate (18), and the oil cylinder of lifting jack (12) top links to each other with mould drain pan (2), and increased pressure board (13) one ends are fixed in rack plate (17) bottom, and the other end connects die cover plate (1); Mould drain pan (2) two sides are provided with leakage check groove (6).
2, detecting instrument for concrete gas seepage coefficient under single-shaft-pressure stress according to claim 1 is characterized in that described mould sample chamber (8) the inner concrete sample that places is provided with sealing gasket (3) perpendicular to two planes of gas flow direction.
3, detecting instrument for concrete gas seepage coefficient under single-shaft-pressure stress according to claim 1, it is characterized in that the side of the mould sample chamber that places (8) inner concrete sample be provided with press seal wedge (4).
4, detecting instrument for concrete gas seepage coefficient under single-shaft-pressure stress according to claim 1, it is characterized in that the profile of the mould sample chamber of surveying (8) inner concrete sample be hexahedron, its length is 70.7～150mm, and width is 70.7～150mm, and thick is 40～70mm.
5, detecting instrument for concrete gas seepage coefficient under single-shaft-pressure stress according to claim 2 is characterized in that described sealing gasket (3) is quadrilateral, and its middle part has circular hole.
6, the method for testing of concrete gas permeability coefficient tester under a kind of uniaxial compressive stress effect as claimed in claim 1 is characterized in that concrete steps are as follows:
(1) reach the concrete sample in regulation length of time and dry under 50 ℃～65 ℃ conditions, the outside surface of concrete sample adopts encapsulation process, and the sample of handling well places drying basin, at room temperature leaves standstill 36～54 hours;
(2) tested sample that obtains in the step (1) is placed testing mould, be pressed into chock, tighten mould, check sealing condition by leakage check groove 6, till air tight, start lifting jack, apply compressive stress on tested sample, pressure effect to this sample testing finishes, and opens compression gas tank, air pressure is transferred to the force value of appointment, keeping the equilibration time of tested sample is 10～20 minutes, so that may be by all being full of the gas that is seen through in the passage of gas, closes compression gas pot valve in the tested sample, the ventilative time of test in the fixed pressure drop segment limit, record should be breathed freely the time; Each tested sample repeats to survey the ventilative time 3～5 times;
(3) change the compressive stress that lifting jack applies, repeat above test, test sees through the ventilative time of tested sample, tries to achieve tested sample infiltration coefficient mean value, gets the test value of 3～5 tested sample infiltration coefficient mean values as this group tested sample; Wherein the infiltration coefficient of tested sample calculates by following formula:
In the formula: D---concrete gas infiltration coefficient, unit are m
2,
P
a---local atmospheric pressure, unit is Pa,
P
1, P
2---initial, the termination force value of fixed pressure drop section, unit is Pa,
Q---gas flow, unit are m
3/ s,
The thickness of L---sample, unit are m,
μ---aerodynamic force viscosity, unit is Pas,
A---the sectional area of breathing freely in the sample, unit is m
2,
The ventilative time of t---measurement, unit is s,
R---gas universal constant,
T---the environment temperature during test, unit is ℃,
V---the volume in confined gas chamber, unit are m
3
7, the method for testing of concrete gas permeability coefficient tester under the uniaxial compressive stress effect according to claim 6 is characterized in that the gas medium in the described compression gas tank is O
2, N
2, air or CO
2
8, the method for testing of concrete gas permeability coefficient tester under the uniaxial compressive stress effect according to claim 6 is characterized in that the fixed pressure drop section variation range in the described step (2) is 0.05MPa～0.2MPa.
9, the method for testing of concrete gas permeability coefficient tester under the uniaxial compressive stress effect according to claim 6, it is characterized in that the profile of the mould sample chamber of surveying (8) inner concrete sample be hexahedron, its length is 70.7～150mm, width is 70.7～150mm, and thick is 40～70mm.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2006100237629A CN1815175A (en) | 2006-02-07 | 2006-02-07 | Detecting instrument for concrete gas seepage coefficient under single-shaft-pressure stress and detecting method |
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Cited By (7)
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| CN102147348A (en) * | 2011-01-25 | 2011-08-10 | 中国科学院山西煤炭化学研究所 | Device and method for measuring gas permeation in coal |
| CN102590062A (en) * | 2012-01-21 | 2012-07-18 | 长安大学 | Asphalt mixture pressure type permeameter and method for measuring permeability |
| CN103245596A (en) * | 2013-05-14 | 2013-08-14 | 南京工程学院 | Method for determining gas permeability coefficient of concrete |
| CN106644823A (en) * | 2016-12-21 | 2017-05-10 | 山西大学 | Air tightness testing device for coal wall coating and air tightness testing method applied to air tightness testing device |
| CN107144512A (en) * | 2017-06-15 | 2017-09-08 | 深圳大学 | A kind of concrete permeability testing device and its test system |
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2006
- 2006-02-07 CN CNA2006100237629A patent/CN1815175A/en active Pending
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102147348A (en) * | 2011-01-25 | 2011-08-10 | 中国科学院山西煤炭化学研究所 | Device and method for measuring gas permeation in coal |
| CN102147348B (en) * | 2011-01-25 | 2012-11-14 | 中国科学院山西煤炭化学研究所 | Device and method for measuring gas permeation in coal |
| CN102590062A (en) * | 2012-01-21 | 2012-07-18 | 长安大学 | Asphalt mixture pressure type permeameter and method for measuring permeability |
| CN102590062B (en) * | 2012-01-21 | 2014-06-04 | 长安大学 | Asphalt mixture pressure type permeameter and method for measuring permeability |
| CN103245596A (en) * | 2013-05-14 | 2013-08-14 | 南京工程学院 | Method for determining gas permeability coefficient of concrete |
| CN106644823A (en) * | 2016-12-21 | 2017-05-10 | 山西大学 | Air tightness testing device for coal wall coating and air tightness testing method applied to air tightness testing device |
| CN107144512A (en) * | 2017-06-15 | 2017-09-08 | 深圳大学 | A kind of concrete permeability testing device and its test system |
| CN111122416A (en) * | 2020-01-17 | 2020-05-08 | 同济大学 | Test system for measuring gas permeation parameters of ultra-low permeability medium under multi-field multi-phase coupling condition |
| CN111122416B (en) * | 2020-01-17 | 2021-12-07 | 同济大学 | Test system for measuring gas permeation parameters of ultra-low permeability medium under multi-field multi-phase coupling condition |
| CN111504876A (en) * | 2020-04-30 | 2020-08-07 | 江苏科技大学 | Device for measuring oxygen diffusion coefficients in concrete with different saturation degrees under continuous tension and compression action |
| CN111504876B (en) * | 2020-04-30 | 2023-08-15 | 江苏科技大学 | Device for measuring oxygen diffusion coefficient in concrete under continuous tension and compression effect |
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