【国外标准】 Standard Test Method for Bulk Electrical Resistivity or Bulk Conductivity of Concrete

5.1 The electrical resistivity of a concrete is the opposition to the movement of ions under an applied electric field. The electrical conductivity of a concrete is a measure of how readily the ions in the pore solution can be transported through the concrete under an applied electric field (the higher the conductivity, the greater the rate of transport). The electrical resistivity or conductivity is a material property that depends upon the pore volume, the pore structure (size and connectivity), the pore solution composition, the degree of saturation of the concrete specimen, and the specimen’s temperature. Concrete mixture characteristics that are known to affect concrete electrical resistivity, as well as resistance to chloride ion penetration, include water-cementitious materials ratio, pozzolans, slag cement, the presence of polymeric admixtures, air-entrainment, aggregate type, aggregate volume fraction, degree of consolidation, curing method, and age.5.2 The bulk electrical resistivity of concrete is the inverse of its bulk electrical conductivity. Bulk electrical conductivity can also be measured by Test Method C1760, which uses the apparatus described in Test Method C1202. This test method, however, uses apparatus specifically designed to measure bulk conductivity or bulk resistivity.5.3 The purpose of conditioning in a simulated pore solution is to bring the specimen to a level of near complete saturation of the capillary and gel pores. When comparing two different concrete specimens, it is important to condition both specimens as close as possible to a comparable saturation state, using the same solution for conditioning, so that values can be compared in a meaningful way. This is particularly true for using the measured resistivity or conductivity, along with other information, to estimate the diffusivity.5.4 The bulk electrical resistivity or conductivity of concrete can provide a rapid indication of its resistance to chloride ion penetration and resistance to penetration of other fluids. Resistivity or conductivity measurements have shown good correlations with other electrical indication tests including Test Method C1202 (1, 2, 3).6 Bulk electrical resistivity results have shown good correlation with bulk diffusion determined using Test Method C1556 on companion molded cylinders from the same concrete mixtures (4).1.1 This test method covers the determination of the bulk electrical resistivity or conductivity of molded specimens or cored sections of hardened concrete after immersion in water saturated with a simulated pore solution in order to provide a rapid indication of its resistance to the penetration of fluids and dissolved aggressive ions.1.2 The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard. If required results obtained from another standard are not reported in the same system of units as used by this standard, it is permitted to convert those results using the conversion factors found in the SI Quick Reference Guide.21.3 The text of this standard references notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of this standard.1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. (Warning—Fresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin and tissue upon prolonged exposure.)3 For specific warning statement see 8.1.2.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.