1、Designation: G 180 04Standard Test Method forInitial Screening of Corrosion Inhibiting Admixtures forSteel in Concrete1This standard is issued under the fixed designation G 180; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes a procedure for determiningthe effects of chemical admixtures on the corrosion of m
3、etals inconcrete. This test method can be used to evaluate materialsintended to inhibit chloride-induced corrosion of steel inconcrete. It can also be used to evaluate the corrosivity ofadmixtures by themselves or in a chloride environment. Thistest is not applicable for emulsions.1.2 UnitsThe value
4、s stated in SI units are to be regardedas standard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safe
5、ty and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 150 Specification for Portland CementC 670 Practice for Preparing Precision Statements for TestMethods for Construction MaterialsD 632 Specification for Sodium
6、 ChlorideE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodG 3 Practice for Conventions Applicable to ElectrochemicalMeasurements in Corrosion TestingG 5 Test Method for Making Potentiostatic and Potentiody-namic Anodic Polarization MeasurementsG 15 Ter
7、minology Relating to Corrosion and CorrosionTestingG 59 Test Method for Conducting Potentiodynamic Polar-ization Resistance Measurements3. Terminology3.1 DefinitionsFor definitions of terms used in this prac-tice see Terminology G 15.4. Significance and Use4.1 This test method provides a means for a
8、ssessingcorrosion-inhibiting concrete admixtures.4.2 This test method is useful for development of admix-tures intended to reduce corrosion of reinforcing steel inconcrete.4.3 This test method is useful in determining the corrosivityof admixtures toward steel reinforcing if the admixture sampleis co
9、mpared to a control without admixtures.4.4 Good performance, a reduction in corrosion rate versuschloride alone by at least one order of magnitude in this test, isa strong indication that an admixture is a corrosion inhibitor.However, poor performance requires additional testing todetermine if the a
10、dmixture improves corrosion resistance.4.5 This method is a screening test and shall not be used topredict performance in the field. However, it is useful todetermine which admixtures shall be included into long-termevaluation programs.4.6 The filtering process makes this test not suitable for theev
11、aluation of emulsions.5. Apparatus5.1 The test cell as described in Test Method G 5.5.2 Potentiostat, as described in Test Method G 5, capableof varying potential at a constant scan rate and measuring theresulting current.5.3 A method of recording the varying potential and result-ing current is need
12、ed.5.4 Electrode holder such as described in Fig. 3 of TestMethod G 5.5.5 Electrodes:5.5.1 Working electrode, prepared from a 12.7 mm length of9.5 mm diameter rod stock. Carbon steel C1215 should beused.NOTE 1If specimen forms are used other than those called for by thistest method, for example flat
13、 sheet specimens, care should be taken not tointroduce crevices which can lead to erroneous results.1This test method is under the jurisdiction of ASTM Committee G01 onCorrosion of Metals and is the direct responsibility of Subcommittee G01.14 onCorrosion of Metals in Concrete, Mortar, or Cement.Cur
14、rent edition approved July 1, 2004. Published July 2004.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copy
15、right ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.6 Auxiliary Electrodes:5.6.1 Two graphite rods or platinized-niobium or platinummesh.5.7 Reference Electrodes:5.7.1 A saturated calomel electrode with a controlled rate ofleakage (about 3
16、L/h) is recommended.6. Reagents and Materials6.1 Type I/II cement (C3A content between 6 and 10 %),according to Specification C 150.6.2 Filter paper with 1.1 m retention.6.3 Teflon stir bars.6.4 Carbon steel C1215 samples.36.5 Sodium chloride, reagent grade, according to Specifica-tion D 632.6.6 Cal
17、cium hydroxide, reagent grade.6.7 Admixtures to be tested.6.8 Carbon dioxide free compressed air.47. Experimental Procedure7.1 Prepare a cement slurry consisting of 1000 g of waterand 200 g cement. Mix thoroughly, stir for 60 min and filter.NOTE 2An admixture should be added at a quantity consistent
18、 with itsaddition rate in concrete. 35 to 965 mL of water is equivalent to 5 L/m3in concrete. If other dosages are desired, proportion them based on thisratio.7.2 Filter, and add 4 g/L calcium hydroxide and stir a further30 min.7.3 Setup a standard electrochemical cell according to TestMethod G 5 an
19、d fill it with 900 mL of filtered slurry solution.Purge the cell with carbon dioxide free air. Air flow rate shouldbe at least 300 cc/min.7.4 Degrease the metal sample by cleaning ultrasonically inhexane for 2 min. If an ultrasonic bath is not available, soak thesamples in hexane and wipe dry. Make
20、sure the sample isthoroughly dried before mounting it on the electrode holder.7.5 While purging the cell with carbon dioxide free air,precondition the electrode in the solution for 24 h.7.5.1 Add NaCl to the solution obtained in 7.3 (having beenpurged for 24 h with CO2-free air), to obtain a 0.5 or
21、a 1Msolution, and continue purging for a further 4 h.NOTE 3The multi-laboratory test was run at the two different chloridelevels to develop the precision statement. The higher chloride level wouldbe representative of a more severe exposure.7.5.2 Measure the open circuit potential.7.5.3 Measure the p
22、olarization resistance (Rp) by recordingthe potentiodynamic polarization curve at a scan rate of 0.167mV/s, from 20 mV to +20 mV versus open circuit potential.7.5.4 Plot the polarization resistance curve as a linearpotential-current density plot as shown in Practice G 3.7.5.5 Determine the polarizat
23、ion resistance Rp, as the tan-gent of the curve at i = 0, as described in Test Method G 59.The corrosion rate is expressed as 1/Rpin S/cm2.NOTE 4An example of a polarization resistance curve is given in theAppendix as Fig. X1.4.8. Interpretation of Results8.1 An admixture is behaving as a corrosion
24、inhibitor in thistest method if the average log10(1/Rp) value is 1.0 or less thanthat of the chloride only average.8.2 If the admixture does not reduce average 1/Rpby anorder of magnitude another test method is needed to determineif it is an inhibitor.8.3 An admixture that increases average 1/Rpby a
25、n order ofmagnitude over a slurry without chloride or inhibitor iscorrosive.NOTE 5The change in log10(1/Rp) by 1.0 is an order of magnitudechange in 1/Rp. Log values are useful in comparing corrosion rates sincerates from different specimens or conditions can differ by orders ofmagnitude making a li
26、near scale less useful.9. Report9.1 Report the following information:9.1.1 Value of the open circuit potential (OCP) versus SCE,and9.1.2 Corrosion rate given by 1/Rpin S/cm2.10. Precision and Bias10.1 Based on the pooled estimates of precision, the follow-ing statement of precision and bias5can be m
27、ade:10.1.1 Interlaboratory Test ProgramAn interlaboratorystudy of a pore solution test for corrosion inhibiting admixturesfor steel reinforcement in concrete was conducted in 2001.Each of six laboratories tested two randomly drawn samples ofeach of four materials (two sodium chloride solutions, 0.5M
28、and 1.0M, each with and without 35 mL/L of a solutioncontaining 30 % calcium nitrite). Practice E 691 was followedfor the design and analysis of the study.10.1.2 Single-Operator PrecisionThe single operatorstandard deviation of the logarithm to the base 10 of a singletest result is 0.36. Therefore,
29、log10(1/Rp) values of two properlyconducted tests by the same operator should not differ by morethan 1.0.10.1.3 Interlaboratory PrecisionThe interlaboratory stan-dard deviation of the logarithm to the base 10 of a single testresult is 0.44. Therefore, log10(1/Rp) values of two properlyconducted test
30、s in different laboratories should not differ bymore than 1.24.NOTE 6These numbers represent, respectively, the (1s) and (2ds)limits as described in Practice C 670.10.2 BiasSince there is no accepted reference materialsuitable for determining the bias in this test method, nostatement on bias is made
31、.11. Keywords11.1 admixtures; cement; corrosion inhibitors; slurry;solution3The samples are cylindrical in shape, with 5.1 cm2exposed area, and can bepurchased from Metal Samples, AL, sample type P/N410.4ACO2free air gas generator (typically used for FT-IR equipment) can be used.5Supporting data hav
32、e been filed at ASTM Headquarters. Request RR:G01-1021.G180042APPENDIX(Nonmandatory Information)X1. PRECISION CALCULATIONSX1.1 Information on the precision of the results obtained bythis test method was derived from an interlaboratory test withtwo samples for each molarity tested, per laboratory. Si
33、xlaboratories participated in the study. Statistical analysis of thedata was performed using Practice E 691 Interlaboratory DataAnalysis Software. Results are shown in the attached Table Afor 1/Rpmeasurements. Values of repeatability (Sr, r), andreproducibility (SR, R) are for the logarithm (base 10
34、) of 1/Rp,where Sr, r, SR, and R are defined as follows:Sr= repeatability standard deviation log(S/cm2 (1s),r = 95 % repeatability limit within a laboratory log(S/cm2 (2ds),SR= reproducibility standard deviation log(S/cm2 (1s),andR = 95 % reproducibility limit between laboratorieslog(S/cm2 (2ds).X1.
35、2 This study meets the minimum requirements fordetermining precision prescribed in Practice E 691 in terms ofthe number of laboratories, materials and determinations (seeAppendix X1, Table X1.1).X1.3 Fig. X1.1 is a graph of r and R versus averagelog10(1/Rp) + 1. Because the ASTM data analysis softwa
36、redoes not accept negative numbers, a value of 1 was added toevery log10(1/Rp) value. Adding a constant to all values doesnot change the standard deviation estimates. It does, however,change the calculated averages. In Table X1.1, the averagevalues were corrected by subtracting 1 from the softwareou
37、tput. In Fig. X1.1, the average values were not corrected.There is no indication that precision varies systematically withaverage level. Therefore, pooled estimates of precision weredetermined which should be valid over the range of 1/Rpencompassed in the interlaboratory study.X1.4 The consistency s
38、tatistics for log10(1/Rp) by labora-tory and by material, are shown in Figs. X1.2 and X1.3,respectively. The h statistic examines consistency of test resultsfrom laboratory to laboratory. The k statistic examines consis-tency of within-laboratory precision from laboratory to labo-ratory. In these pl
39、ots, the horizontal lines are the critical valuesfor h and k at the 0.5 % statistical significance level. There area couple of excursions beyond the critical values for h or k ineach plot, but there are no consistent patterns of concern in theplots. Therefore, the data appear consistent for purposes
40、 of thisanalysis.X1.5 Example of a polarization resistance curve:TABLE X1.1 Statistical Analysis of Corrosion Potential DataPractice E 691 Interlaboratory Data Analysis SoftwareThe number of laboratories, materials, and determinations in this study DOESmeet the minimum requirements for determining p
41、recision prescribed in PracticeE 691:ThisStudyPractice E 691MinimumLaboratories 6 6Materials 4 3Determinations 2 2Precision Statement for Test MethodPrecision and Reproducibility of Log10(1/Rp) for Each MaterialPrecision, characterized by repeatability (Sr, r) and reproducibility (SR, R) hasbeen det
42、ermined for the materials to be:Material Average SrSRrR(All dimensions are Log10(S/cm2)0.5M NaCl 1.65 0.38 0.59 1.05 1.640.5M NaCl + Ca(NO2)20.42 0.34 0.40 0.95 1.111.0M NaCl 1.66 0.17 0.23 0.49 0.661.0M NaCl + Ca(NO2)20.49 0.43 0.43 1.20 1.20Precision and Reproducibility of Log10(1/Rp) Pooled Over
43、All MaterialsAverage SrSRrR(All dimensions are Log10(S/cm2)1.06 0.36 0.44 1.00 1.24where:Sr= repeatability standard deviationr = 95 % repeatability limit (within laboratory)SR= reproducibility standard deviationR = 95 % reproducibility limit (between laboratories)G180043FIG. X1.1 r and R versus Mate
44、rial AveragesAnalysis: Log10(1/Rp)+1G180044FIG. X1.2 Consistency Statistics by LaboratoryAnalysis: Log10(1/Rp)+1FIG. X1.3 Consistency Statistics by MaterialAnalysis: Log10(1/Rp)+1G180045ASTM International takes no position respecting the validity of any patent rights asserted in connection with any
45、item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical c
46、ommittee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at
47、a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Dr
48、ive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).FIG. X1.4 Polarization Resistance CurveG180046
