Electrochemical Test Methods to Evaluate the Corrosion Potential of Earthen Materials (2021) / Chapter Skim
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7 1.1 Introduction Electrochemical properties of earthen materials such as electrical resistivity, pH, salt concentrations, and organic content are commonly used to characterize their corrosion potential. AASHTO test standards, adopted in the early 1990s, are among the most common practices in the United States to determine the electrochemical properties of earthen materials.
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8 Electrochemical Test Methods to Evaluate the Corrosion Potential of Earthen Materials 4. Develop a test protocol and corresponding characterization of corrosion potential that more accurately reflects the corrosivity of earthen materials as compared with the conventional methods.
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Background 9 • The maximum corrosion occurs at a critical moisture content in a soil mass. Above the critical moisture content, the corrosion rate is controlled by the conductivity of the soil–water mixture (i.e., controlled by activation, or the rate by which electrons from the metal are transferred to oxygen molecules through the electrolyte)
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10 Electrochemical Test Methods to Evaluate the Corrosion Potential of Earthen Materials ASTM WK24621 and Tex-129-M are new test methods (under development during the course of this research, 2016–2019) being considered for implementation by ASTM and the Texas DOT.
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Background 11 specimens are useful in investigating the influence of moisture content, level of compaction, and distribution of particle size (i.e., tortuosity of the current flow path) on specimen resistivity.
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12 Electrochemical Test Methods to Evaluate the Corrosion Potential of Earthen Materials AASHTO T 288, ASTM G187, ASTM WK24621, Tex-129-E, and Tex-129-M differ in terms of sample treatments (whether or not the sample is dried before distilled water is added in increments) , the particle size distribution of the specimen, the manner in which the soil sample is mixed with water, and the moisture conditions during the test.
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Background 13 The samples are syphoned via syringes and filtered before the analytical tests are conducted by IEC to determine the sulfate and chloride contents. The USGS Field Leach Test applies to poorly graded sands, gravels, and aggregate mixtures.
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14 Electrochemical Test Methods to Evaluate the Corrosion Potential of Earthen Materials No. 10 sieve, a sufficient amount of fines for testing might be obtained from sieving a large quantity of the material.
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