Comparing Resistivity and Conductivity in Metal Culverts

Details

• Creators:
  Collison, Jake
• Corporate Creators:
  Agua del Sol Consultants, LLC.
• Corporate Contributors:
  New Mexico. Department of Transportation
• Subject/TRT Terms:
  Corrosion Electrical Conductivity Field Tests Gypsum Metal Culverts Moisture Content Resistivity Method Soil Conductivity Soil Resistivity Soil Stabilization
• Publication/ Report Number:
  CO6444
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States ; New Mexico
• Edition:
  Final Report 2025
• Corporate Publisher:
  New Mexico. Department of Transportation
• Abstract:
  Before installing an underground metal culvert, certain soil characteristics need to be measured to calculate its expected service life. The service life of an underground culvert is a function of the expected amount of corrosion based on the soil, the type of culvert used, and water conditions. The New Mexico Department of Transportation (NMDOT) uses three different soil properties to estimate culvert service life: (1) the soil’s electrical conductivity (EC); (2) pH level; and (3) gypsum content. Soil EC measures how easily an electric charge can be passed (conducted)through the soil, with the soil’s moisture content having a large effect. Soils with pH lower than 5.5 and greater than 7.3 have been shown to have adverse effects on galvanized coated (zinc coating)steel culverts. Lastly, knowing the amount of gypsum (CaSO4 2H2O) in the soil is important because gypsum (specifically, the sulfates within the gypsum, SO42) readily corrodes zinc and steel. All three of these soil properties’ corrosive potential is further increased with higher moisture content in the soil. With culverts’ typical proximity to water, accurate accounting of these soil parameters is crucial in the determination of the type of culvert to be used, based on a minimum of 50 years of service life. This project used in-situ and laboratory measurements of soil conductivity and resistivity to determine the compatibility of the Natural Resource Conservation Service (NRCS) Soils Maps for metal corrosion potential versus the 2018 NMDOT Culvert Resistant Spreadsheet (CRS).
• Format:
  PDF
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:7d6e900f53413e3bb1ee6fa936f480104284ed30210072fa40eb836fbec952904d7c15227bfe1d5e7d24135ee4a601424363192875f5efe507560aebbcaf4316
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/92348/dot_92348_DS1.pdf
• File Type:
  [PDF - 11.07 MB ]