1、Designation: C1760 12Standard Test Method forBulk Electrical Conductivity of Hardened Concrete1This standard is issued under the fixed designation C1760; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the bulkelectrical conductivity of saturated specimens of hardenedconcrete to provide a ra
3、pid indication of the concretesresistance to the penetration of chloride ions by diffusion (SeeNote 1). The results of this test method can be related to theapparent chloride diffusion coefficient that is determined usingTest Method C1556.NOTE 1The term “bulk” is used because the electrical conducti
4、vity isdetermined by measuring the current passing through all the phases of atest specimen (e.g., cement paste, sand, aggregate). This is accomplishedusing electrodes that cover the ends of the specimen. Other test methodsthat measure conductivity may use probes placed on the side surface of thespe
5、cimen.1.2 UnitsThe values 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 est
6、ablish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. (WarningFreshhydraulic cementitious mixtures are caustic and may causechemical burns to exposed skin and tissue upon prolongedexposure.2)2. Referenced Documents2.1 ASTM Standards:
7、3C31/C31M Practice for Making and Curing Concrete TestSpecimens in the FieldC42/C42M Test Method for Obtaining and Testing DrilledCores and Sawed Beams of ConcreteC125 Terminology Relating to Concrete and Concrete Ag-gregatesC192/C192M Practice for Making and Curing ConcreteTest Specimens in the Lab
8、oratoryC511 Specification for Mixing Rooms, Moist Cabinets,Moist Rooms, and Water Storage Tanks Used in theTesting of Hydraulic Cements and ConcretesC1202 Test Method for Electrical Indication of ConcretesAbility to Resist Chloride Ion PenetrationC1543 Test Method for Determining the Penetration ofC
9、hloride Ion into Concrete by PondingC1556 Test Method for Determining the Apparent ChlorideDiffusion Coefficient of Cementitious Mixtures by BulkDiffusion3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method, referto Terminology C125.4. Summary of Test Method4.1 This
10、test method measures the electrical current througha saturated concrete specimen with a potential difference of 60V dc maintained across the ends of the specimen. Testspecimens can be 100 mm diameter by 200 mm long moldedcylinders or nominal 100 diameter cores with length rangingfrom 100 to 200 mm.
11、The apparatus and specimen conditioningprocedures are the same as described in Test Method C1202,except that the side of the specimen does not have to be sealed.The current is measured 1 min after the voltage is first applied.The measured current, the applied voltage, and the specimendimensions are
12、used to calculate the bulk electrical conductiv-ity of the concrete.5. Significance and Use5.1 This test method measures the bulk electrical conduc-tivity of concrete, which has a theoretical relationship to thediffusion coefficient of chloride ion, or other ions, in theconcrete (1, 2).4Experimental
13、 data confirm that there is acorrelation between the apparent chloride diffusion coefficientmeasured by Test Method C1556, or similar method, and thebulk electrical conductivity (3, 4).5.2 A number of factors are known to affect electricalconductivity of concrete: water cementitious materials ratio,
14、1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.66 on Concretes Resistance to Fluid Penetration.Current edition approved Jan. 1, 2012. Published February 2012. DOI: 10.1520/C1760-12.2See section
15、on Safety Precautions, Manual of Aggregate and Concrete Testing,Annual Book of ASTM Standards, Vol. 04.02.3For 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 standa
16、rds Document Summary page onthe ASTM website.4The boldface numbers in parentheses refer to a list of references at the end ofthis standard.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.the type and amount of supplementary cementiti
17、ous materials,presence of polymeric admixtures, admixtures that containsoluble salts, specimen age, air-void system, aggregate type,degree of consolidation, degree of saturation, and type ofcuring. Different curing methods are used in this test methoddepending on whether the concrete contains supple
18、mentarycementitious materials. Use the same method and duration ofcuring when comparing mixtures.5.3 This test method is suitable for evaluation of concretemixtures for proportioning purposes and for research anddevelopment. Specimens must be sufficiently saturated formeasured electrical conductivit
19、y to provide an indication of theresistance of the concrete to chloride ion penetration. Becausethe electrical conductivity depends upon the degree of satura-tion, specimens are vacuum saturated before testing to ensurea common reference state for comparison purposes. If thespecimen is tested in a p
20、artially saturated, or “as delivered”state, it shall be noted in the test report.5.4 This test can be used to evaluate the electrical conduc-tivity of concretes in structures for applications that mayrequire such information, such as the design of cathodicprotection systems.5.5 The type of specimen
21、and conditioning procedure de-pends on the purpose of the test. For evaluation of concretemixtures, specimens are 100 mm diameter molded cylindersthat are moist cured up to the time of testing. For evaluation ofconcrete samples taken from structures, specimens are 100 mmdiameter cores that are vacuu
22、m saturated before performing thetest.5.6 Age of the test specimen may have significant effects onthe test results, depending on the type of concrete and thecuring procedure. Most concretes, if properly cured, becomeprogressively and significantly less conductive with time.5.7 Measured electrical co
23、nductivity can be used as a basisfor determining the acceptability of a concrete mixture.NOTE 2Because the method and duration of curing of test specimensaffect the test results, the acceptance criteria will need to specify the curingprocedure and test age.6. Interferences6.1 This test method can pr
24、oduce misleading results if one iscomparing concrete mixtures with and without soluble chemi-cal admixtures such calcium nitrite (See Note 3). Calciumnitrite increases greatly the conductivity of the pore solution.For two concrete samples with the same microstructure, theelectrical conductivity of c
25、oncrete made with a calcium nitriteadmixture will be greater than that of the same concretewithout calcium nitrite. This could be interpreted falsely as alower resistance to chloride ion penetration. Long-term chlo-ride ponding tests indicated that concretes with calcium nitritewere at least as resi
26、stant to chloride ion penetration as thecontrol mixtures (See Note 4).NOTE 3Procedures are available for estimating the pore solutionconductivity from the concentration of ionic species present in the solution(5).NOTE 4Other admixtures that provide large quantities of ions mightaffect results of thi
27、s test similarly. Long term ponding tests using TestMethod C1543 or diffusion testing using Test Method C1556 are recom-mended if an admixture effect is suspected.6.2 Because the test results are a function of the electricalresistance of the specimen, the presence of reinforcing steel orother embedd
28、ed electrically conductive materials, includingsome types of aggregates, may yield unrepresentative results,as these will result in higher conductivity than a concrete ofsimilar quality but with no embedded conductive material.Therefore, the test is not valid for specimens containingreinforcing stee
29、l.7. Apparatus7.1 Vacuum Saturation ApparatusAs described in TestMethod C1202.7.2 Movable Bed, Water-Cooled Diamond Saw or SiliconCarbide SawFor trimming test specimen to test length, ifrequired.7.3 Applied Voltage CellsAs described in Test MethodC1202.7.4 Voltage Application and Data Readout Appara
30、tusAsdescribed in Test Method C1202.7.5 Jaw Caliper, Micrometer or Diameter TapeFor mea-suring specimen diameter, readable to at least the nearest 0.1mm. Depth of jaw for a jaw caliper shall be at least 70 mm.7.6 Jaw CaliperFor measuring specimen length, with ameasuring range up to at least 250 mm a
31、nd readable to at leastthe nearest 0.1 mm.8. Reagents and Materials8.1 Sodium Chloride Solution3.0 % by mass (reagentgrade) in distilled water.8.2 Specimen-Cell SealantAs described in Test MethodC1202. Needed if rubber gaskets are not used to seal testspecimen in voltage cells.8.3 Filter PaperNo. 2,
32、 90-mm diameter. This is notrequired if rubber gaskets are used to seal test specimen involtage cells.9. Test Specimens9.1 Molded Cylinders9.1.1 Prepare 100 mm by 200 mm cylindrical specimens inaccordance with Practice C192/C192M or Practice C31/C31M,whichever is applicable. The method of final curi
33、ng depends onwhether the concrete contains supplementary cementitiousmaterials. Unless otherwise directed by the specifier of tests,moist cure specimens in accordance with 9.1.2 for concretemixtures containing only portland cement. For concrete mix-tures containing supplementary cementitious materia
34、ls, moistcure in accordance with 9.1.3 or 9.1.4 as directed by thespecifier of tests. If no specific instructions are provided, curemixtures containing supplementary cementitious materials inaccordance with 9.1.3.9.1.2 Basic Moist CuringCure test specimens for 28 daysin accordance with Practice C192
35、/C192M for specimens pre-pared in the laboratory or in accordance with the standardcuring procedure of Practice C31/C31M for specimens pre-pared in the field. During final moist curing, free water must bepresent on the surfaces of the test specimens. If the moist roomis not able to maintain this con
36、dition, cure the specimens inwater storage tanks in accordance with Specification C511.C1760 1229.1.3 Extended Moist CuringCure test specimens for 56days in accordance with Practice C192/C192M for specimensprepared in the laboratory or in accordance with the standardcuring procedure of Practice C31/
37、C31M for specimens pre-pared in the field. During final moist curing, free water must bepresent of the surface of the test specimens. If the moist roomis not able to maintain this condition, cure the specimens inwater storage tanks in accordance with Specification C511.NOTE 5The 56-day moist curing
38、period is to allow for some supple-mentary cementitious materials to develop potential properties because oftheir slower rate of reaction. Concrete containing supplementary cemen-titious materials may continue to show reductions in conductivity beyond56 days. In some cases, the specifier of tests ma
39、y require testing at laterages, such as 3 months.9.1.4 Accelerated Moist CuringProvide 7 days of stan-dard curing in accordance with Practice C192/C192M forspecimens prepared in the laboratory or in accordance withPractice C31/C31M for specimens prepared in the field. After7 days of standard curing,
40、 immerse the specimens for 21 daysin lime-saturated water at 38.0 6 2.0 C.NOTE 6The accelerated moist curing procedure has been found usefulin providing an earlier indication of potential property development withslower reacting supplementary cementitious materials (6). The extendedmoist curing meth
41、od and accelerated curing method may not provide thesame results. The curing method will be selected by the specifier of testsso that it is in agreement with the established acceptance criteria.9.2 Cores9.2.1 Take cores using a water-cooled coring drill equippedwith a 100-mm inside diameter diamond-
42、dressed core bit. Drillcores in accordance with Test Method C42/C42M Mat loca-tions indicated by the specifier of tests.9.2.2 After drilling, wipe the surface of the core with a wetrag and place the core in a sealable plastic bag or container. Itis not necessary to allow the surface water to evapora
43、te beforeplacing the core in the bag or container.9.2.3 Transport cores to the laboratory in the sealed bags orcontainer. If cores must be shipped, they shall be packed so asto be protected from freezing and from mechanical damageduring transit.9.2.4 If the concrete surface where the core is taken h
44、asbeen modified, for example, by texturing or by applying curingcompounds, sealers, or other surface treatments, trim off thatsurface using a water-cooled diamond-dressed saw appropriatefor the task.9.2.5 If the core is not a full depth core, cut off the fracturedend, using a water-cooled diamond-dr
45、essed saw, so that the cutend is approximately perpendicular to the core axis. Unlessotherwise specified, the trimmed length of the core shall bebetween 100 and 200 mm, and shall be at least three times thenominal maximum size of aggregate.NOTE 7As the specimen length decreases, it is expected that
46、therewill be more variability in replicate test results because of variability inaggregate content within the specimen. The exact effect of specimenlength on the variability of measured conductivity is not known. Thespecifier of tests may require more replicate tests if cores are less than 100mm lon
47、g.10. Conditioning10.1 Before testing, condition core specimens in accordancewith the conditioning procedure in Test Method C1202 unlessotherwise specified.NOTE 8If the purpose of testing cores is to evaluate the in-placeconductivity, the specifier of tests may require that cores be tested in the“as
48、 received” condition.10.2 Molded cylinders shall be in a saturated condition atthe time of test by using one of the curing methods describedin 9.1.11. Procedure11.1 Remove the specimen from water and blot off excesswater from the side of the specimen.11.1.1 Measure the length of the specimen to the
49、nearest 0.1mm along four lines spaced approximately 90 apart. If therange of lengths exceeds 5 mm, trim the end or ends of thespecimen to achieve acceptance (See Note 9). Repeat themeasurement of the length as stated above. If the ends of themolded specimens are convex or concave by more than 5 mmrelative to the perimeter, trim the out-of plane end and measurethe length as stated above. Calculate the average length to thenearest 0.1 mm.NOTE 9A large range of measured lengths indicates that one or bothof the ends of the specimens are not perpendicular to the
