1、Designation: G 180 07Standard 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 covers a procedure for determining theeffects of chemical admixtures on the corrosion of meta
3、ls 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 The values stated
4、 in SI units are to be regarded asstandard. 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 safety and h
5、ealth 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 and Bias Statementsfor Test Methods for Construction MaterialsD 632 Specification for Sodiu
6、m ChlorideE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodG3 Practice for ConventionsApplicable to ElectrochemicalMeasurements in Corrosion TestingG5 Reference Test Method for Making Potentiostatic andPotentiodynamic Anodic Polarization MeasurementsG1
7、5 Terminology Relating to Corrosion and CorrosionTestingG59 Test Method for Conducting Potentiodynamic Polar-ization Resistance Measurements3. Terminology3.1 DefinitionsFor definitions of terms used in this prac-tice see Terminology G15.4. Significance and Use4.1 This test method provides a means fo
8、r assessingcorrosion-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
9、 compared 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 th
10、e admixture improves corrosion resistance.4.5 This test method is a screening test and shall not be usedto predict 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 f
11、or theevaluation of emulsions.5. Apparatus5.1 The test cell as described in Test Method G5.5.2 Potentiostat, as described in Test Method G5, 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 i
12、s needed.5.4 Electrode holder such as described in Fig. 3 of TestMethod G5.5.5 Electrodes:5.5.1 Working electrode, prepared from a 12.7 mm length of9.5 mm diameter rod stock. Carbon steel C1215 should beused.1This test method is under the jurisdiction of ASTM Committee G01 onCorrosion of Metals and
13、is the direct responsibility of Subcommittee G01.14 onCorrosion of Metals in Construction Materials.Current edition approved Nov. 1, 2007. Published December 2007. Originallyapproved in 2004. Last previous edition approved in 2004 as G 18004.2For referenced ASTM standards, visit the ASTM website, ww
14、w.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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE
15、 1If specimen forms are used other than those called for by thistest method, for example flat sheet specimens, care should be taken not tointroduce crevices which can lead to erroneous results.5.6 Auxiliary ElectrodesTwo graphite rods or platinized-niobium or platinum mesh.5.7 Reference ElectrodesA
16、saturated calomel electrodewith a controlled rate of leakage (about 3 L/h) is recom-mended.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 PTFE stir bars.6.4 Carbon steel C1215 samples, cylindri
17、cal in shape, with5.1 cm2exposed area.36.5 Sodium chloride, reagent grade, according to Specifica-tion D 632.6.6 Calcium 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
18、200 g cement. Mix thoroughly, stir for 60 min and filter.NOTE 2An admixture should be added at a quantity consistent with itsaddition rate in concrete. Water measured at 35 to 965 mL is equivalent to5 L/m3in concrete. If other dosages are desired, proportion them based onthis ratio.7.2 Filter, and a
19、dd 4 g/Lcalcium hydroxide and stir a further30 min.7.3 Setup a standard electrochemical cell according to TestMethod G5and 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
20、ultrasonically inhexane for 2 min. If an ultrasonic bath is not available, soak thesamples in hexane and wipe dry. Make 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
21、 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 a 1Msolution, and continue to stir and purge for a further 4 h. After4 h, stop stirring and continue purging for a another 20 h.NOTE 3The multi-laboratory test was run at the two d
22、ifferent 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 polarization resistance (Rp) by recordingthe potentiodynamic polarization curve at a scan rate of0.167 mV/
23、s, from 20 mV to +20 mV versus open circuitpotential.7.5.4 Plot the polarization resistance curve as a linearpotential-current density plot as shown in Practice G3.7.5.5 Determine the polarization resistance Rp, as the tan-gent of the curve at i = 0, as described in Test Method G59.The corrosion rat
24、e is expressed as 1/Rpin S/cm2.NOTE 4An example of a polarization resistance curve is given in Fig.X1.4.8. Interpretation of Results8.1 An admixture is behaving as a corrosion 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 th
25、e 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 an order ofmagnitude over a slurry without chloride or inhibitor iscorrosive.NOTE 5The change in log10(1/Rp) by 1.0 is an ord
26、er 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 linear scale less useful.9. Report9.1 Report the following information:9.1.1 Value of the open circuit potential (OCP) versus
27、SCE,and9.1.2 Corrosion rate given by 1/Rpin S/cm2.10. Precision and Bias510.1 Based on the pooled estimates of precision, the follow-ing statement of precision and bias can be made:10.1.1 Interlaboratory Test ProgramAn interlaboratorystudy of a pore solution test for corrosion inhibiting admixturesf
28、or 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, 0.5Mand 1.0M, each with and without 35 mL/L of a solutioncontaining 30 % calcium nitrite). Practice E 691 was followedfor the d
29、esign 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, log10(1/Rp) values of two properlyconducted tests by the same operator should not differ by morethan 1.0.10.1.3 Interlabora
30、tory 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 tests in different laboratories should not differ bymore than 1.24.3The sole source of supply of the apparatus known to the com
31、mittee at this timeis Metal Samples,AL, sample type P/N410. If you are aware of alternative suppliers,please provide this information to ASTM International Headquarters. Your com-ments will receive careful consideration at a meeting of the responsible technicalcommittee,1which you may attend.4ACO2fr
32、ee air gas generator (typically used for FT-IR equipment) can be used.5Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: G01-1021.G180072NOTE 6These numbers represent, respectively, the (1s) and (2ds)limits as described in Practic
33、e C 670.10.2 BiasSince there is no accepted reference materialsuitable for determining the bias in this test method, nostatement on bias is made.11. Keywords11.1 admixtures; cement; corrosion inhibitors; slurry;solutionAPPENDIX(Nonmandatory Information)X1. PRECISION CALCULATIONSX1.1 Information on t
34、he precision of the results obtained bythis test method was derived from an interlaboratory test withtwo samples for each molarity tested, per laboratory. Sixlaboratories participated in the study. Statistical analysis of thedata was performed using Practice E 691 Interlaboratory DataAnalysis Softwa
35、re. Results are shown in the attached Table Afor 1/Rpmeasurements. Values of repeatability (Sr, r), andreproducibility (SR, R) are for the logarithm (base 10) 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
36、 a laboratory log(S/cm2 (2ds),SR= reproducibility standard deviation log(S/cm2 (1s),andR = 95 % reproducibility limit between laboratorieslog(S/cm2 (2ds).X1.2 This study meets the minimum requirements fordetermining precision prescribed in Practice E 691 in terms ofthe number of laboratories, materi
37、als and determinations (seeTable X1.1).X1.3 Fig. X1.1 is a graph of r and R versus averagelog10(1/Rp) + 1. Because the ASTM data analysis softwaredoes 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
38、estimates. It does, however,change the calculated averages. In Table X1.1, the averagevalues were corrected by subtracting 1 from the softwareoutput. In Fig. X1.1, the average values were not corrected.There is no indication that precision varies systematically withaverage level. Therefore, pooled e
39、stimates of precision weredetermined which should be valid over the range of 1/Rpencompassed in the interlaboratory study.X1.4 The consistency statistics 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 result
40、sfrom laboratory to laboratory. The k statistic examines consis-tency of within-laboratory precision from laboratory to labo-ratory. In these plots, the horizontal lines are the critical valuesfor h and k at the 0.5 % statistical significance level. There area couple of excursions beyond the critica
41、l values for h or k ineach plot, but there are no consistent patterns of concern in theplots. Therefore, the data appear consistent for purposes of thisanalysis.X1.5 Fig. X1.4 is an example of a polarization resistancecurve.TABLE X1.1 Statistical Analysis of Corrosion Potential DataPractice E 691 In
42、terlaboratory Data Analysis SoftwareThe number of laboratories, materials, and determinations in this study DOESmeet the minimum requirements for determining precision prescribed in PracticeE 691:ThisStudyPractice E 691MinimumLaboratories 6 6Materials 4 3Determinations 2 2Precision Statement for Tes
43、t MethodPrecision and Reproducibility of Log10(1/Rp) for Each MaterialPrecision, characterized by repeatability (Sr, r) and reproducibility (SR, R) hasbeen determined 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)2
44、0.42 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 All MaterialsAverage SrSRrR(All dimensions are Log10(S/cm2)1.06 0.36 0.44 1.00 1.24where:Sr= repeatability standard deviationr = 95 % repeata
45、bility limit (within laboratory)SR= reproducibility standard deviationR = 95 % reproducibility limit (between laboratories)G180073FIG. X1.1 r and R versus Material AveragesAnalysis: Log10(1/Rp)+1G180074FIG. X1.2 Consistency Statistics by LaboratoryAnalysis: Log10(1/Rp)+1FIG. X1.3 Consistency Statist
46、ics by MaterialAnalysis: Log10(1/Rp)+1G180075ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, an
47、d the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revisi
48、on of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you sh
49、ouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, 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 CurveG180076
