CN102621041A - Method for testing calcium ion diffusion coefficient of concrete - Google Patents
Method for testing calcium ion diffusion coefficient of concrete Download PDFInfo
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- CN102621041A CN102621041A CN2012101067758A CN201210106775A CN102621041A CN 102621041 A CN102621041 A CN 102621041A CN 2012101067758 A CN2012101067758 A CN 2012101067758A CN 201210106775 A CN201210106775 A CN 201210106775A CN 102621041 A CN102621041 A CN 102621041A
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Abstract
The invention relates to a method for testing calcium ion diffusion coefficient of concrete, and the method comprises the following steps: cutting concrete into a sheet test sample, placing into a vacuum water holding device, dry-vacuuming, injecting a calcium hydroxide saturated solution into a vacuum chamber, and wet-vacuuming to form saturate concrete in the calcium hydroxide solution; applying voltage to the test sample, and measuring the calcium ion migration rate; and calculating the calcium ion diffusion coefficient according to Nernst-Plank equation. The calcium ion diffusion coefficient of concrete can be used for evaluating the permeability of concrete. The method provided by the invention has the following advantages: the method can be used for measuring the calcium ion diffusion coefficient of concrete, the method is simple, the data are accurate and reliable, and the method is suitable for both ordinary concrete and high performance concrete.
Description
Technical field
The present invention relates to a kind of method of testing concrete calcium ion coefficient of diffusion, belong to the concrete technology field.
Background technology:
It is one of principal element that causes the xoncrete structure results in premature failure that ion is invaded.The for example steel bar corrosion that causes of chlorion, the concrete spalling that sulfate ion causes, hydrated calcium silicate decomposition that magnesium ion causes etc.Ion is invaded the inner main process of concrete material and is comprised: diffusion, infiltration, capillary absorption, migration and convection current.Diffusion is one of them main process.Therefore, concrete ionic diffusion coefficient is significant for research concrete structure durability and life prediction as the important indicator of concrete material permanance.Confirm that science, reasonable, reliable and effective test method are most important.
At present, concrete material ionic diffusion coefficient method of testing is mainly the chloride diffusion coefficient method of testing.Mainly contain following several kinds: (1) electric flux method comprises state's standard material test association criterion (ASTM C1202) and American National highway and transportation standard (AASHTO T277); (2) stable state electromigration test method, Norske standard test method (NT Build 355); (3) unstable state electromigration test method, Norske standard test method (NT Build 492).(4) full salt electrical conductivity method.Above method can only be tested the chloride diffusion coefficient of concrete material, does not also test the test method of other ionic diffusion coefficients of concrete material up to now.
The objective of the invention is to propose a kind of concrete material calcium ion coefficient of diffusion method of testing.With the concrete sample of laminating, adopt the vacuscope aqua calcis of satisfying then, under certain voltage, make the calcium ion migration afterwards, calculate the calcium ion coefficient of diffusion through measuring the calcium ion migration rate.Concrete structure durability problem and harmful ion are invaded closely related, and can be known that by the electrobalance principle diffusion of yin, yang ion must be to carry out simultaneously, and both influence each other.Therefore, it is significant to study the transfer abilities in concrete such as other kation such as calcium ion.Simultaneously, calcium ion coefficient of diffusion and chloride diffusion coefficient have correlativity, can estimate the resisting chloride ion penetration infiltration capability of concrete material with the calcium ion coefficient of diffusion.Calcium ion is the intrinsic ion of concrete material, and calcium ion coefficient of diffusion method of testing can not introduced other ion, and is harmless to concrete sample.
Summary of the invention:
The concrete calcium ion coefficient of diffusion method of testing of the present invention's design comprises following step:
(1) concrete is cut into 1-5cm thin slice sample;
(2) concrete sample is put into vacuum water conservation appearance, keep the vacuum tightness below the 100kPa then, dry tap 3 hours.Keep vacuum tightness, in the full water appearance of vacuum, inject the calcium hydroxide saturated solution, concrete sample is immersed in the calcium hydroxide saturated solution fully, wet taking out 1 hour.Stop to vacuumize, under atmospheric pressure, keep concrete sample in the calcium hydroxide saturated solution, to soak 20 hours;
(3) concrete sample to full aqua calcis applies 60 volts of DC voltages, measures 1 hour migration rate with interior calcium ion;
(4), calculate concrete calcium ion coefficient of diffusion with formula (1) according to above-mentioned voltage and calcium ion migration rate.
In the formula: D
CaBe calcium ion coefficient of diffusion (m
2/ s), dc/dt is calcium ion migration rate (mol/m
3/ s), T is absolute temperature (K), and R is gas law constant (83.1J/K/mol), and z is calcium ion electric weight (2), and C is saturated aqua calcis calcium ion concentration (0.0233 * 10
3Mol/m
3), F is a Faraday constant (9.65 * 10
4C/mol), E is DC voltage (60V), V cathode solution volume (m
3), L is specimen thickness (m), A is concrete sample cross-sectional area (m
2).
The pore structure decision ionic diffusion coefficient of concrete material.For with a kind of concrete material, the coefficient of diffusion of different ions has correlativity.Adopt parallel chlorion stable state electromigration test to compare with method of testing of the present invention, the relation between the calcium ion coefficient of diffusion that the present invention measures and the chloride diffusion coefficient of stable state electromigration determination of test method is seen Fig. 1.Test findings shows that calcium ion coefficient of diffusion and chloride diffusion coefficient have good correlativity, and the calcium ion coefficient of diffusion that the present invention measures is accurate.
Method of testing of the present invention has been confirmed corresponding test technology, can in 25 hours, accurately measure the calcium ion coefficient of diffusion of concrete material, is the present unique a kind of method of testing that can fast, accurately measure concrete calcium ion coefficient of diffusion.The present invention has the following advantages: (1) this method is based on the design of ion-conductance transport theory, clear principle; (2) device therefor is simple, and laboratory, scene all can possess; (3) measure simply, calculate easy.(4) can accurately measure concrete calcium ion coefficient of diffusion, to the concrete sample not damaged.(5) the calcium ion coefficient of diffusion of this method mensuration and the chloride diffusion coefficient of stable state electromigration determination of test method have good correlativity, and chloride diffusion coefficient can convert.
Description of drawings:
Fig. 1 is the graph of a relation between the chloride diffusion coefficient of the calcium ion coefficient of diffusion measured of the present invention and stable state electromigration determination of test method.
Embodiment:
The test ultimate principle is the ion-conductance transport theory.Concrete material can suppose that hole solution is saturated aqua calcis after handling through the full aqua calcis of vacuum.Through applying certain DC voltage, make calcium ion under the driving of voltage, form stable migration stream.At this moment, the migration rate of concrete calcium ion coefficient of diffusion decision calcium ion.Then can calculate the calcium ion coefficient of diffusion through measuring the calcium ion migration rate.Theoretical calculation formula is the Nernst-Plank formula.
Specimen preparation comprises two parts: the one, concrete is cut into the thin slice of suitable thickness; The 2nd, concrete sample is carried out the full aqua calcis of vacuum.
The thickness of concrete sample depends on the maximum aggregate size size, for the desirable 5cm of normal concrete.Carry out perviousness relatively or qualitative relatively the time, can be less than 5cm, but should be less than 1cm, with the macropore of avoiding occurring in the concrete sample being communicated with.
Full aqua calcis is handled and can be adopted the natural immersion method, is about to concrete sample and is soaked in the saturated onium hydroxide solution, and soak time is 4-8 week; Also can adopt the vacuum aqua calcis of satisfying, concrete technology is: concrete sample vertically is placed in the vacuscope, guarantees between the sample spacing that 1cm is above to keep the vacuum tightness below the 100kPa then, dry tap 3 hours.Keep vacuum tightness, in the full water appearance of vacuum, inject the calcium hydroxide saturated solution, concrete sample is immersed in the calcium hydroxide saturated solution fully, wet taking out 1 hour.Stop to vacuumize, depress, keep concrete sample in the calcium hydroxide saturated solution, to soak 20 hours at normal atmosphere.Saturated aqua calcis is by distilled water and the preparation of analysis pure cerium hydroxide calcon.
The calcium ion migration rate is measured and is adopted stable state electromigration test method (NT Build 355) test flume.Calcium ion concentration is measured and can be adopted EDTA titrimetry, the chromatography of ions or flame emission spectrometry to measure in the cathode can.After starting 60 volts of DC voltages, every 5ml solution of from downstream slot, getting at a distance from 12 minutes.Measure the calcium ion concentration of 5 samples after the off-test in 1 hour, and calculate the calcium ion migration rate.Can obtain the calcium ion coefficient of diffusion according to calcium ion migration rate and formula (1).Test temperature is 20 ± 5 ℃.
Embodiment one
Sample: Beijing University of Technology's sample, match ratio is seen table 1.Wherein 0.45OPC is a normal concrete, and water-cement ratio is 0.45, and 0.38OPC has reduced water consumption, and water-cement ratio is 0.38, and 0.45PFA has mixed flyash, and 0.45GGBS has mixed slag, and 0.45MS has mixed the silicon ash.
Use the concrete corning machine to drill through the right cylinder of diameter 20cm * 20cm * 20cm sample as 10cm along building direction.Using concrete cutting machine to cut thickness at the right cylinder middle part tests as the concrete thin slice sample of 5cm.Concrete calcium ion coefficient of diffusion is measured the result and is seen table 2.
Table 1 concrete sample match ratio
Table 2 concrete calcium ion coefficient of diffusion
| Numbering | Calcium ion coefficient of diffusion (10 -12m 2/s) |
| 0.38OPC | 8.37 |
| 0.45OPC | 12.23 |
| 0.45PFA | 3.95 |
| 0.45GGBS | 2.36 |
| 0.45MS | 5.48 |
Claims (1)
1. a method of testing concrete calcium ion coefficient of diffusion is characterized in that, this method may further comprise the steps:
(1) concrete is cut into 1-5cm thin slice sample;
(2) concrete sample is put into vacuum water conservation appearance, keep the vacuum tightness below the 100kPa then, dry tap 3 hours; Keep vacuum tightness, in the full water appearance of vacuum, inject the calcium hydroxide saturated solution, concrete sample is immersed in the calcium hydroxide saturated solution fully, wet taking out 1 hour; Stop to vacuumize, under atmospheric pressure, keep concrete sample in the calcium hydroxide saturated solution, to soak 20 hours;
(3) concrete sample to full aqua calcis applies 60 volts of DC voltages, measures 1 hour migration rate with interior calcium ion;
(4), calculate concrete calcium ion coefficient of diffusion with formula (1) according to above-mentioned voltage and calcium ion migration rate;
In the formula: D
CaBe the calcium ion coefficient of diffusion, unit is m
2/ s, dc/dt are the calcium ion migration rates, and unit is mol/m
3/ s, T are absolute temperature, and unit is K, and R is a gas law constant, and z is the calcium ion electric weight, are 2, and C is saturated aqua calcis calcium ion concentration, are 0.0233 * 10
3Mol/m
3, F is a Faraday constant, and E is a DC voltage, is 60V, and V cathode solution volume, unit are m
3, L is a specimen thickness, and unit is m, and A is the concrete sample cross-sectional area, and unit is m
2
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104062208A (en) * | 2014-06-30 | 2014-09-24 | 上海华力微电子有限公司 | Method for determining diffusion coefficient of oxygen in silicon substrate in dry-oxygen diffusion process |
| CN104865163A (en) * | 2014-02-26 | 2015-08-26 | 中交四航工程研究院有限公司 | Method and system for lossless measurement and concrete durability inference |
| CN105092423A (en) * | 2014-05-14 | 2015-11-25 | 中交四航工程研究院有限公司 | Advanced prediction method for chloride ion permeability resistance of concrete based on water binder ratio monitoring |
| CN108982301A (en) * | 2018-07-05 | 2018-12-11 | 河海大学 | A kind of measurement device and measuring method of hydrated calcium silicate gel chloride diffusion coefficient |
| CN109406551A (en) * | 2018-12-11 | 2019-03-01 | 吉林大学 | A kind of analysis method for testing asphalt internal structure feature |
| CN111896428A (en) * | 2020-08-10 | 2020-11-06 | 南京工业大学 | Device and method for measuring diffusion coefficient of sulfate ions in mortar and concrete |
| JP7461708B2 (en) | 2020-03-30 | 2024-04-04 | 太平洋セメント株式会社 | How to measure expansion strain |
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| CN1111737C (en) * | 1999-09-10 | 2003-06-18 | 清华大学 | Rapid evaluation method for concrete permeability |
| JP2005164257A (en) * | 2003-11-28 | 2005-06-23 | Okumura Corp | Method for judging deterioration of concrete structure |
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Patent Citations (4)
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| JPH06317560A (en) * | 1993-04-30 | 1994-11-15 | Tokyo Electric Power Co Inc:The | Estimation method of compression strength of concrete by rapid chlorine ion permeability test |
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Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104865163A (en) * | 2014-02-26 | 2015-08-26 | 中交四航工程研究院有限公司 | Method and system for lossless measurement and concrete durability inference |
| CN104865163B (en) * | 2014-02-26 | 2018-06-08 | 中交四航工程研究院有限公司 | A kind of lossless measurement and the method and system for estimating endurance performance of concrete |
| CN105092423A (en) * | 2014-05-14 | 2015-11-25 | 中交四航工程研究院有限公司 | Advanced prediction method for chloride ion permeability resistance of concrete based on water binder ratio monitoring |
| CN105092423B (en) * | 2014-05-14 | 2018-05-08 | 中交四航工程研究院有限公司 | A kind of ion penetration resistance of concrete advanced prediction method based on water-cement ratio monitoring |
| CN104062208A (en) * | 2014-06-30 | 2014-09-24 | 上海华力微电子有限公司 | Method for determining diffusion coefficient of oxygen in silicon substrate in dry-oxygen diffusion process |
| CN104062208B (en) * | 2014-06-30 | 2016-08-17 | 上海华力微电子有限公司 | Oxygen determination method of diffusion coefficient in silicon chip in dry oxygen diffusion process |
| CN108982301A (en) * | 2018-07-05 | 2018-12-11 | 河海大学 | A kind of measurement device and measuring method of hydrated calcium silicate gel chloride diffusion coefficient |
| CN108982301B (en) * | 2018-07-05 | 2020-09-29 | 河海大学 | Device and method for measuring diffusion coefficient of chloride ions in calcium silicate hydrate gel |
| CN109406551A (en) * | 2018-12-11 | 2019-03-01 | 吉林大学 | A kind of analysis method for testing asphalt internal structure feature |
| CN109406551B (en) * | 2018-12-11 | 2021-11-30 | 吉林大学 | Analysis method for testing internal structure characteristics of asphalt mixture |
| JP7461708B2 (en) | 2020-03-30 | 2024-04-04 | 太平洋セメント株式会社 | How to measure expansion strain |
| CN111896428A (en) * | 2020-08-10 | 2020-11-06 | 南京工业大学 | Device and method for measuring diffusion coefficient of sulfate ions in mortar and concrete |
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Application publication date: 20120801 |