Most corrosive characteristics and conditions affected the _______ of a soil.

• A. Electrical resistivity
• B. Water content
• C. Grain size distribution
• D. Texture

Answer: (A)

Corrosion of buried metal pipes is driven by how easily ions flow through the surrounding soil. The property that directly governs that flow is electrical resistivity. Soils with low resistivity conduct ions and electrons more readily, creating a more corrosive environment for metals; high resistivity soils resist flow and tend to be less corrosive. Water content does influence resistivity, since wetter soils conduct electricity better, but the measure used to gauge corrosivity—the factor that determines how aggressive the soil is toward metals—is electrical resistivity. Grain size distribution and texture affect physical properties like drainage and pore structure, not the chemical drive of corrosion, so they’re less directly tied to corrosivity. Therefore, electrical resistivity is the best descriptor of most corrosive characteristics and conditions in soil.