AASHTO T 358-2015 Standard Method of Test for Surface Resistivity Indication of Concrete’s Ability to Resist Chloride Ion Penetration.pdf
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1、Standard Method of Test for Surface Resistivity Indication of Concretes Ability to Resist Chloride Ion Penetration AASHTO Designation: T 358-151American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-3c T 358-1 AASHTO Stan
2、dard Method of Test for Surface Resistivity Indication of Concretes Ability to Resist Chloride Ion Penetration AASHTO Designation: T 358-1511. SCOPE 1.1. This test method covers the determination of the electrical resistivity of water-saturated concrete to provide a rapid indication of its resistanc
3、e to the penetration of chloride ions. This test method is applicable to types of concrete where correlations have been established between this test procedure and long-term chloride diffusion procedures such as those described in ASTM C1556. Examples of such correlations are discussed in the refere
4、nce shown in Section 15.2. 1.2. The values stated in SI units are to be regarded as the standard. 1.3. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and heal
5、th practices and determine the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: R 39, Making and Curing Concrete Test Specimens in the Laboratory T 23, Making and Curing Concrete Test Specimens in the Field T 24M/T 24, Obtaining and Testing Drilled
6、 Cores and Sawed Beams of Concrete T 277, Electrical Indication of Concretes Ability to Resist Chloride Ion Penetration 2.2. ASTM Standards: C670, Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials C1202, Standard Test Method for Electrical Indi
7、cation of Concretes Ability to Resist Chloride Ion Penetration C1556, Standard Test Method for Determining the Apparent Chloride Diffusion Coefficient of Cementitious Mixtures by Bulk Diffusion 3. SUMMARY OF TEST METHOD 3.1. This test method consists of measuring the resistivity of 200-mm (8-in.) or
8、 300-mm (12-in.) nominal length and 100-mm (4-in.) or 150-mm (6-in.) nominal diameter cylinders or cores by use of a 4-pin Wenner probe array. An alternating current (AC) potential difference is applied by the surface resistivity apparatus at the outer pins of the Wenner array generating current flo
9、w in the concrete. The resultant potential difference between the two inner pins is measured. The current used and resultant potential along with the affected sample area are used to calculate the resistivity 2015 by the American Association of State Highway and Transportation Officials.All rights r
10、eserved. Duplication is a violation of applicable law.TS-3c T 358-2 AASHTO of the concrete. The resistivity, in kilohms-centimeters (k-cm), has been found to be related to the resistance of the specimen to chloride ion penetration. 4. SIGNIFICANCE AND USE 4.1. This test method covers the laboratory
11、evaluation of the electrical resistivity of concrete samples to provide a rapid indication of their resistance to chloride ion penetration. Wenner probe measurements have shown good correlations with other electrical indication tests such as the T 277 and the ASTM C1202 tests. In most cases, the ele
12、ctrical resistivity results have shown good correlation with chloride exposure tests, such as ASTM C1556, on companion cylinders cast from the same concrete mixtures (see references in Sections 15.2, 15.4, and 15.5). 4.2. This test method is suitable for evaluation of materials and material proporti
13、ons for design purposes, as well as for research and development. 4.3. The qualitative terms in the left-hand column of Table 1 should be used in most cases unless otherwise noted by the specifying agency. The numerical results (resistivity, in k-cm) from this test method must be used with caution,
14、especially in applications such as quality control and acceptance testing. Table 1Chloride Ion Penetration Chloride Ion Penetration Surface Resistivity Test 100-by-200-mm (4-by-8-in.) Cylinder (k-cm) a = 1.5 150-by-300-mm (6-by-12-in.) Cylinder (k-cm) a = 1.5 High 254 199 a = Wenner probe tip spacin
15、g 4.4. The details of the test method apply to 100-mm (4-in.) and 150-mm (6-in.) nominal diameter specimens. Other specimen diameters may be tested with appropriate changes to the Wenner probe tip spacing and the correction factor in the calculating equation. (See reference in Section 15.3.) 2015 by
16、 the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 358-3 AASHTO Figure 1Four-Point Wenner Array Probe Test Setup 5. INTERFERENCES 5.1. This test method can produce misleading results when calcium nitrite h
17、as been admixed into a concrete. The results from this test on concrete mixtures including calcium nitrite indicate lower resistivity values, that is, lower resistance to chloride ion penetration, when compared to tests on identical concrete mixtures (controls) without calcium nitrite. However, long
18、-term chloride diffusion tests indicate the concretes with calcium nitrite were at least as resistant to chloride ion penetration as the control mixtures. Note 1Other admixtures might affect results of this test similarly. Long-term diffusion tests are recommended if an admixture effect is suspected
19、. 5.2. Sample curing condition is known to affect the resistivity of the solution in the pore structure (see Section 15.4). Lime-water curing on average reduces resistivity by 10 percent. 5.3. Because the test results are a function of the electrical resistance of the specimen, the presence of reinf
20、orcing steel or other embedded electrically conductive materials may have a significant effect. The test is not valid for samples containing reinforcing. 5.4. Sample age may have significant effects on the test results, depending on the type of concrete and the curing procedure. Most concretes, if p
21、roperly cured, become progressively and significantly less permeable with time. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 358-4 AASHTO 5.5. The degree of water saturation and concrete tempe
22、rature may have a significant effect on the electrical resistivity of concrete. A standardized conditioning procedure has been developed to minimize this effect. 5.6. Factors that are known to affect resistivity as well as chloride ion penetration include water/cement ratio, pozzolans, the presence
23、of polymeric admixtures, air-void system, aggregate type, and degree of consolidation. 6. APPARATUS 6.1. Surface Resistivity ApparatusApparatus needs to be able to supply a flat-topped trapezoidal wave at a frequency of about 13 Hz and a pk-pk level with a nominal voltage limit of 25V pk-pk. Use a W
24、enner probe capable of an adjustment of the probe tip spacing to 38.1 mm (1.5 in.). Figure 2Surface Resistivity Apparatus with 4-Pin Wenner Probe Array 6.2. Specimen holder to prevent specimen rotation while under test. (See Figure 3 for example.) 2015 by the American Association of State Highway an
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