A number in parentheses indicates the year of last reapproval. Terminology sion activity of the reinforcing steel. Terminology G Concrete surface in building interiors and desert environments lose sufficient moisture so that the concrete resistivity becomes 4. Significance and Use so high that special testing techniques not covered in this test 4. Concrete surfaces that for use in research and development work.
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A number in parentheses indicates the year of last reapproval. Terminology sion activity of the reinforcing steel. Terminology G Concrete surface in building interiors and desert environments lose sufficient moisture so that the concrete resistivity becomes 4.
Significance and Use so high that special testing techniques not covered in this test 4. Concrete surfaces that for use in research and development work. The basic configuration of the electrical 4. Concrete cover in excess of 3 in. The values given in parentheses are mathematical that can result in a loss of the ability to discriminate variation conversions to SI units that are provided for information only in relative corrosion activity.
It is the responsibility of the user of this standard to establish appro- 4. Referenced Documents engineers or technical specialists experienced in the fields of concrete materials and corrosion testing. It is often necessary to 2. Published April Originally 5. Last previous edition approved in as C— DOI: stable and reproducible potential for the measurement of the Calomel reference electrodes have been used in laboratory studies. For concrete submerged in seawater, using silver-silver chloride reference electrodes avoids chloride contamination problems that may occur with copper-copper sulfate electrodes.
Potentials mea- sured by reference electrodes other than saturated copper- copper sulfate should be converted to the copper-copper sulfate 4 FIG. This has been accomplished by using no more than a total of electrode. It shall consist of a sponge or several sponges linear ft m of at least AWG No. The wire pre-wetted with a low electrical resistance contact solution. Calibration and Standardization 5. One such solution is composed of a mixture of contaminated. The porous plug salt bridge shall be covered 95 mL of wetting agent commercially available wetting agent when not in use for long periods to ensure that it does not or a liquid household detergent thoroughly mixed with 5 gal become dried to the point that it becomes a dielectric upon 19 L of potable water.
If cells do not measured corrosion potential that can derive from dynamic produce the reproducibility or agreement between cells de- liquid junction potentials. On large horizontal reinforced scribed in Section 12, cleaning may rectify the problem. The use of a meter with variable surface of the concrete member, it is of little value to take two input impedance avoids meter loading errors from high con- measurements from virtually the same point.
Conversely, crete resistivity. The spacing shall there- constant through two successive increases. Then decrease the fore be consistent with the member being investigated and the impedance on setting to reduce noise and provide the most intended end use of the measurements Note 1. Logging evaluation of structures with large horizontal surfaces like bridge decks. Generally, larger spacings increase the probability that localized corrosion voltmeters may also be used.
Measurements may be taken in either a grid or 5. Spacing between measurements should generally be from nearby ac power lines or radio frequency transmitters can reduced where adjacent readings exhibit reading differences exceeding 50 produce error. When in the proximity of such interference mV areas of high corrosion activity. Cracks, cold joints, and areas with dynamic structural activity can produce areas of localized corrosion sources, the readings may fluctuate. For small, lightly reinforced members, it may be advantageous to map the reinforcement locations with a cover meter and place the 5 reference electrode over the bars on a suitable grid.
Ives, D. If pre-wetting cannot obtain condition 1 , either the temporary or permanent connection is required. Make a direct electrical resistance of the circuit is too great to obtain valid electrical connection to the reinforcing steel by means of a corrosion potential measurements of the steel, or stray current compression-type ground clamp, by brazing or welding a from a nearby direct current traction system or other fluctuating protruding rod, or by using a self tapping screw in a hole direct-current, such as arc welding, is affecting the readings.
In drilled in the bar. To ensure a low electrical resistance either case, the reference electrode method should not be used. In certain cases, this technique may require removal of pre-wetting is required to obtain condition 1 as described in some concrete to expose the reinforcing steel.
Electrically 7. Accomplish this by spraying or otherwise wetting connect the reinforcing steel to the positive terminal of the either the entire concrete surface or only the points of mea- voltmeter. Special care should be exercised with prestressing surement as described in 7. No free surface water should remain between grid points should be made. Where welding is employed to make connec- when potential measurements are initiated.
Leave the sponges in place for the period of time necessary to 7. Do not remove the steel except in cases where it can be documented that an sponges from the concrete surface until after the reference exposed steel member is directly attached to the reinforcing electrode potential reading is made. In making the corrosion steel. Certain members, such as expansion dams, date plates, potential measurements, place the electrical junction device lift works, scuppers, drains, and parapet rails may not be described in 5.
Electrical continuity of steel compo- nents with the reinforcing steel can be established by measur- 7. Where duplicate test measurements are continued not necessarily the location of corrosion activity. The precise over a long period of time, identical connection points should location of corrosion activity requires knowledge of the elec- be used each time for a given measurement. While underwater measurements are mat being measured is electrically continuous by checking possible, results regarding the location of corrosion must be electrical continuity between diagonally opposite ends of the interpreted very carefully.
Underwater, or other situations area surveyed. Reduction of oxygen availability will shift the electrode and the other end of this same lead wire to the rebar corrosion potential significantly in the electronegative negative ground terminal of the voltmeter.
Often it is not possible to precisely locate points of underwater corrosion activity in salt water environments be- 7. Recording Corrosion Potential Values 7. However, if condition 2 is observed, 8. Report all corrosion potential values in volts and voltage reading is stable The tempera- electrode tip, provided that the steel does not have a metallic ture coefficient for the correction is given in 5.
The numeric magni- tude does not indicate the corrosion rate of the steel. The 9. Data Presentation Numeric Magnitude Technique is not applicable to concrete 9. The first, an equipotential contour map, provides tions as may be found in tunnels, basements, water tanks, and a graphical delineation of areas in the member where corrosion submerged situations. The second method, the cumulative Localized corrosion typically plan view of the concrete member, plot the locations of the manifests considerable change in potential over relatively short corrosion potential values of the steel in concrete and draw distances hundreds of millivolts over a few hundred millime- contours of equal potential through points of equal or interpo- tres.
Relatively negative potentials with little deviation may lated equal values. The maximum contour interval shall be indicate corrosion is possible, but that oxygen availability is 0. An example is shown in Fig. Interpretation of Results See Refs and is coated, and under many other conditions, requires an Appendix X1 experienced corrosion engineer or specialist, and may require Guidelines and test Technique, or a combination of the two.
Corrosion potentials may in part or in portland cement mortar or concrete, and near the reference whole reflect the chemistry of the electrode environment. For example, increasing concentrations of chloride can reduce the ferrous ion concentration at a steel anode, thus lowering 6 The boldface numbers in parentheses refer to the list of references at the end of making more negative the potential.
Unless such chemistry, this standard. Precision and Bias7 chloride reference electrode are shown in Table 2. The varia- The repeatability limit for the repeatability and reproducibility. Repeatability is within labo- program was also calculated as 2. The reproducibility standard mens are run in different laboratories. The varia- means of an interlaboratory test program in which the corro- tions were not significantly different so a pooled standard sion potential of five slabs of concrete with embedded steel deviation was calculated representing the result of this program rods were each measured at twelve points in a three by four of 20 mV.
Six laboratories collected data using the saturated calculated as 2. The reason for this difference was not determined. Slab No.
ASTM C 876 Portugues
You are on page 1of 8 Search inside document 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. Designation: C 15 Corrosion Potentials of Uncoated Reinforcing Steel in Concrete1 This standard is issued under the fixed designation C; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon indicates an editorial change since the last revision or reapproval. Terminology sion activity of the reinforcing steel.
Designation: C 15 Corrosion Potentials of Uncoated Reinforcing Steel in Concrete1 This standard is issued under the fixed designation C; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon indicates an editorial change since the last revision or reapproval. Terminology sion activity of the reinforcing steel. Terminology G Concrete surface in building interiors and desert environments lose sufficient moisture so that the concrete resistivity becomes 4. Significance and Use so high that special testing techniques not covered in this test 4.
ASTM C876- 15 Corrosion Potentials of Uncoated Reinforcing Steel in Concrete
G 3 Prtica para convenes aplicveis a medidas eletroqumicas em Teste de Corroso 3. Significado e Uso 3. Muitas vezes, necessrio o uso de outros dados, como teores de cloreto, profundidade de carbonatao, resultados da pesquisa delaminao, taxa de resultados de corroso e condies de exposio ambientais, alm de medidas de potencial de meia clula, para formular concluses sobre a atividade de corroso do ao incorporado e seu provvel efeito sobre a vida de uma estrutura de atendimento. A soluo deve ser preparada com cristais de sulfato de cobre de grau reagente dissolvidos em gua destilada ou desionizada. A soluo pode ser considerado saturado quando um excesso de cristais no dissolvidas encontra-se no fundo da soluo.