Electrochemical Test Methods to Evaluate the Corrosion Potential of Earthen Materials (2021) / Chapter Skim
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From page 51... ...
51 4.1 Introduction During Phase III of NCHRP Project 21-11 the research team cooperated with selected transportation agencies that implemented the recommended protocol as a shadow specification. The data include characterization of different sample sources (e.g., maximum particle size and gradation)
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52 Electrochemical Test Methods to Evaluate the Corrosion Potential of Earthen Materials of Texas at El Paso and to state DOT geotechnical laboratories to determine gradation, resistivity, pH, and salt and sulfate content. Table 4-1 summarizes the laboratory tests performed on the samples obtained from the site and the source by the owner and/or the research group at the University of Texas at El Paso.
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Field Measurements 53 Location of the shoulder 42°59'49"N 78°51'34.5"W 42.996944, - 78.859583 Location of MSE wall 31°48'03.1"N 106°18'52.8"W 31.80086428, - 106.31466715 Location of the MSE wall 29°26'18.7"N 98°22'48.2"W 29.438528, -98.380056 (a)
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54 Electrochemical Test Methods to Evaluate the Corrosion Potential of Earthen Materials and PP#10 -- and from the suggested protocol (appendix; see also Figure 3-14) , samples from Buffalo and El Paso should be evaluated using the current AASHTO tests (particles passing the No.
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From page 55... ...
Field Measurements 55 Figure 4-4 presents laboratory measurements of resistivity from samples retrieved from sources and sites in Buffalo, Schroon, San Antonio, and El Paso. This figure includes the results from testing samples according to AASHTO T 288 and Tex-129-M and data obtained by owners and contractors as well as by the University of Texas at El Paso (through the research team)
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56 Electrochemical Test Methods to Evaluate the Corrosion Potential of Earthen Materials 12 in., and 24 in.) was used between the probes.
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Field Measurements 57 the moisture content and electrochemical properties of the soil were collected farther away from the wet region of the soil. These samples were sealed and stored in double Ziploc plastic bags to prevent evaporation and contamination.
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Field Measurements 59 a total of 6 ft long and included resistivity measurements at probe spacings of 0.5, 1.0, and 2.0 ft. At some locations, the 1- or 2-ft probe spacing could not be achieved because of space constraints.
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60 Electrochemical Test Methods to Evaluate the Corrosion Potential of Earthen Materials from these laboratory tests were extrapolated to moisture contents of 3.0%, 2.5%, and 7.3%, as shown in Figure 4-9, and these values were compared with the field/in situ measurements at depths of 6 in. As shown in Table 4-3, a good comparison was obtained.
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From page 61... ...
Field Measurements 61 97 311 46 61 15 24 43 35 169 133 15 9 1 1 35 29 0 50 100 150 200 250 300 350 UTEP/Source UTEP/Site UTEP/Source UTEP/Site UTEP/Source UTEP/Site UTEP/Source UTEP/Site Buffalo, NY Schroon, NY San Antonio, TX El Paso, TX S ul fa te c on te nt ( m g/ kg ) AASHTO T 290 Tex-620-M Figure 4-11.
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From page 62... ...
62 Electrochemical Test Methods to Evaluate the Corrosion Potential of Earthen Materials Table 4-4 shows the results of electrochemical tests performed on the samples retrieved from the sites and from the sources. The laboratory results of the resistivity tests are discussed in Section 4.3.1 (see Figure 4-4)
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From page 63... ...
Field Measurements 63 in excess of those needed to achieve 100% saturation, a slurry is tested rather than a compacted specimen. This comparison provides useful information to estimate the behavior of the material in worst-case scenarios and to determine the possible underestimation/ overestimation of the reported resistivity.
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