CN1087426C - Fast evaluation method for relative permeability of concrete - Google Patents
Fast evaluation method for relative permeability of concrete Download PDFInfo
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- CN1087426C CN1087426C CN 98126398 CN98126398A CN1087426C CN 1087426 C CN1087426 C CN 1087426C CN 98126398 CN98126398 CN 98126398 CN 98126398 A CN98126398 A CN 98126398A CN 1087426 C CN1087426 C CN 1087426C
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- concrete
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- limit
- permeability
- perviousness
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- 239000004567 concrete Substances 0.000 title claims abstract description 55
- 230000035699 permeability Effects 0.000 title claims abstract description 16
- 238000011156 evaluation Methods 0.000 title claims description 10
- 238000000034 method Methods 0.000 claims abstract description 21
- 230000015556 catabolic process Effects 0.000 claims abstract description 13
- 238000012360 testing method Methods 0.000 claims abstract description 9
- 238000010276 construction Methods 0.000 abstract 1
- 239000000463 material Substances 0.000 description 6
- 239000004574 high-performance concrete Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 239000004568 cement Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 230000035515 penetration Effects 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- 238000003869 coulometry Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000002715 modification method Methods 0.000 description 2
- 241000370738 Chlorion Species 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000002103 osmometry Methods 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
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- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The present invention relates to a method for quickly evaluating the permeability of concrete. In the method, concrete is cut into sheets of 5 to 30mm, the sheets are placed between two electrodes, current is applied between the two electrodes, current density is from 0.01 to 1 mA/cm<2>, voltage is increased to a limit or breakdown voltage, the limit or the sparking voltage of concrete under the same test condition is compared, the permeability of concrete is low if limit voltage is high, and the permeability of concrete is high if limit voltage is low. The permeability of concrete can be evaluated rapidly and simply by the present invention, and the present invention is suitable for the technical fields of construction, roads, bridges, hydraulic engineering and harbor engineering.
Description
Technical field
The present invention relates to a kind of quick evaluation concrete permeability method of quality relatively, belong to the concrete technology field.
Background technology
The method that is used to estimate concrete permeability now mainly contains following several: (1) osmometry comprises permeable method and air permeability method.This method is a kind of more traditional method of testing, is applicable to normal concrete, is unsuitable for high performance concrete; (2) coulometry comprises ASTM C1202 and modification method thereof.ASTM C1202 mainly is to be that 50mm, diameter are that the concrete sample of 100mm is under the 60V DC voltage by measuring thickness, the electric weight size that flows through in 6 hours is evaluated concrete perviousness, the electric weight that flows through is many more, illustrate that the passage in the concrete is many more, so perviousness is just big more, as shown in Figure 1.This method also only is suitable for normal concrete, and is inapplicable to high performance concrete.Modification method mainly is to have reduced voltage, has prolonged the time, and its fatal shortcoming is the same with ASTMC1202, and evaluation high performance concrete time error is bigger; (3) electromigration, this method has multiple, Tang-Nilsson method that the most successful is (ACI Materials Journal Vol.89, No.1,1992,49-53), promptly to being soaked in 3%NaCl-Ca (OH)
2The concrete sample of solution applies 30V voltage, and the energising certain hour is measured the length of penetration of chlorion with development process, use afterwards a reduced equation (
D is a coefficient of diffusion, and a, b, c are known constant, and t is a time of penetration, and x is a length of penetration) obtain chloride diffusion coefficient to estimate concrete perviousness.The shortcoming of this method is comparatively complicated, data parsing needs certain galvanochemistry knowledge, and the civil engineering work personnel do not possess often, in addition, because the galvanization time is longer, ion concentration in the concrete hole solution changes greatly, adds that the mean depth time error of measuring chloride permeability is also bigger, makes that the data that calculate at last are not accurate enough.In addition, the same with coulometry, applied voltage is higher, causes the serious polarization of electrode and the composition of hole solution to change easily.So, also do not have preferably a kind ofly up to now, both be suitable for the rapid evaluation normal concrete, also be suitable for evaluating the infiltrative method of high performance concrete.
Generally speaking, material is fine and close more, and porosity is low more, and withstand voltage properties is good more, and perviousness is low more, and impermeability is good more; Vice versa.The withstand voltage properties of material, promptly anti-electrical breakdown capability, not only relevant, also relevant with its micromechanism with the composition of material.High electrical breakdown theory about insulating material mainly contains electric breakdown, thermal breakdown and electrochemical breakdown theory (referring to Zhu Deheng, Yan Zhang chief editor's " High-Voltage Insulation " at present, the 186th page, publishing house of Tsing-Hua University, February in 1992 the 1st edition), do not come it is quantitatively described but also have unified theory and formula so far.Yet any is arranged is identifiable, and promptly material is more not fine and close, and its withstand voltage properties is poor more.
Summary of the invention
The objective of the invention is to propose a kind of quick evaluation concrete permeability method of quality relatively, estimate the height of concrete permeability with concrete withstand voltage properties, it is concrete according to being: (1) concrete insulate in the normal state, can think dielectric material; (2) concrete is the heterogeneous random material with labyrinth, is wherein certainly existing the weakest link; What (3) concrete perviousness reflected in fact promptly is link the weakest in the concrete, and its withstand voltage properties also reflects identical path.
The quick evaluation concrete permeability that the present invention proposes is the method for quality relatively, and at first concrete cutting being become thickness is the thin slice of 5～30mm, is placed between two electrodes, limits certain electric current between two electrodes, and current density is 0.01～1mA/cm
2, making alive compares the concrete limit or voltage breakdown under the same test condition to the limit or voltage breakdown then, and the limit or voltage breakdown are high more, and then concrete perviousness is low more, and the limit or voltage breakdown are low more, and then concrete perviousness is high more.
In the evaluation method of the present invention, at first concrete cutting is become the thin slice of suitable thickness, be generally less than or equal the maximum gauge of aggregate, usually desirable 5～30mm; Then directly or dry to constant weight under proper temperature, be placed between two electrodes, limit an electric current (size depends on instrument range and electrode area), common desirable current density is 0.01～1mA/cm
2, making alive is to the limit (or puncture) voltage then.By comparing the concrete limit (or puncture) voltage under the same test condition, can determine the relative height of concrete permeability; The limit or voltage breakdown are high more, and perviousness is low more, otherwise then high more.
Evaluation method of the present invention has the following advantages: (1) device therefor is simple, easily buys.(2) measurement is simple, quick, can measure to finish in a few minutes.(3) both be applicable to normal concrete, also be applicable to high performance concrete.
Description of drawings:
Fig. 1 is the experimental result of measuring with the ASTM C1202 method of prior art.
Fig. 2 is the concrete corresponding limiting voltage (being converted to voltage strength) under certain current limit (being converted to current density) that is obtained by the present invention, sample drying 48 hours, wherein Fig. 2 (a) is the result with DC measurement, and Fig. 2 (b) exchanges electrometric result for using.
Concrete under certain current limit the corresponding limiting voltage (be converted to voltage strength) of Fig. 3 for being obtained by the present invention, sample dries to constant weight.
Table 1 is each concrete mixture ratio and the anti-mechanical pressure intensity of standard curing after 28 days among the figure.
Specific implementation method example one:
1, electrode used therein is diameter 50mm, thickness 25mm, surface smoothness is the fine copper electrode of 7, used high-voltage power supply is the CY2661 type AC/DC withstands voltage tester that Changzhou radio instrument factory produces, voltage range is 2500, two grades of 5000V, and electric current is 0.5,1,5,10, five grades of 20mA.
2, for avoiding surface conduction, the test specimen area should be greater than electrode area.When electrode diameter was 50mm, concrete sample can be with the thin slice of 100 * 100mm, the desirable size identical of thickness with maximum diameter of aggrogate, and that also can cut as required is thinner, and when qualitative more concrete perviousness, desirable specimen thickness is 5～10mm.The used maximum aggregate size of concrete is 20mm in this example, and because of more fine or not, we get the concrete sheet thickness is 10mm.
3, to the concrete of match ratio as shown in table 1, be shaped to the test block of 100 * 100 * 300mm, maintenance was cut into the thick thin slice of 10mm after 28 days, embezzled water (can adopt natural immersion or vacuum satisfy water technology) at saturated Ca (OH) 2 solution then.Dried 48 hours down at 50 ℃ more afterwards, the making alive experimental result is seen Fig. 2, and Vb is the limit electric field intensity corresponding to current limit density Ig (current limit is 0.5mA) among the figure.As shown in Figure 1, the concrete that water cement ratio is big more, no matter its limiting voltage is to exchange or direct current, all low more, so perviousness is also big more.
Example two:
1, device therefor is the high direct voltage tester of developing voluntarily, and range is 50000V, 2mA.
2, concrete is cut into the thin slice of 20mm, (drying time was generally several days) dries to constant weight under 50 ℃.Current limit is 2mA, and other test condition is identical with example one, and measured result is seen Fig. 3.As shown in Figure 3, after the test specimen oven dry, it is big that its limit (puncture) voltage obviously becomes, but the comparing result unanimity, promptly its perviousness of the concrete that water cement ratio is big more is big more.
The test result of ASTM C1202 method is seen Fig. 1.Because of electric weight is big more, concrete permeability is big more, so consistent in this scope of experiment with the result who is measured by ASTM C1202 method by the experimental result that the present invention measured.Table 1 is each concrete mixture ratio and the anti-mechanical pressure intensity of standard curing after 28 days among each figure
| Specimen coding (kg/m 3) | Water cement ratio (kg/m 3) | East, Ji 525# cement (kg/m 3) | Sand intensity (MPa) | Rubble | Mark was supported 28 days |
| C1 C2 C3 C4 | 0.40 0.45 0.50 0.55 | 480 480 480 480 | 663 663 663 663 | 1081 1081 1081 1081 | 63 49 39 39 |
Claims (1)
1, the fine or not relatively method of a kind of quick evaluation concrete permeability, it is characterized in that: it is the thin slice of 5～30mm that concrete cutting is become thickness, is placed between two electrodes, applies electric current between two electrodes, current density is 0.01～1mA/cm
2, making alive compares the concrete limit or voltage breakdown under the same test condition to the limit or voltage breakdown then, and limiting voltage is high more, and then concrete perviousness is low more, and limiting voltage is low more, and then concrete perviousness is high more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 98126398 CN1087426C (en) | 1998-12-31 | 1998-12-31 | Fast evaluation method for relative permeability of concrete |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 98126398 CN1087426C (en) | 1998-12-31 | 1998-12-31 | Fast evaluation method for relative permeability of concrete |
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| Publication Number | Publication Date |
|---|---|
| CN1224839A CN1224839A (en) | 1999-08-04 |
| CN1087426C true CN1087426C (en) | 2002-07-10 |
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| CN 98126398 Expired - Fee Related CN1087426C (en) | 1998-12-31 | 1998-12-31 | Fast evaluation method for relative permeability of concrete |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| RU2705655C1 (en) * | 2019-03-13 | 2019-11-11 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Тамбовский государственный технический университет" (ФГБОУ ВО "ТГТУ") | Method of determining diffusion coefficient in solid articles from orthotropic capillary-porous materials |
| RU2705706C1 (en) * | 2019-03-13 | 2019-11-11 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Тамбовский государственный технический университет" (ФГБОУ ВО "ТГТУ") | Method of determining diffusion coefficient in solid articles from capillary-porous materials |
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- 1998-12-31 CN CN 98126398 patent/CN1087426C/en not_active Expired - Fee Related
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