SEDL / STP / STP1095-EB / STP23556S

Effects of Small Concentrations of Soluble Salts on Hydrometer Analysis

Picornell, M
Assistant professor, research assistant, and research assistant, University of Texas, El Paso, TX

El-Jurf, QS
Assistant professor, research assistant, and research assistant, University of Texas, El Paso, TX

Abd Rahim, MA
Assistant professor, research assistant, and research assistant, University of Texas, El Paso, TX

Pages: 11    Published: Jan 1990

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Abstract

Hydrometer analysis normally is performed on a soil specimen mixed with a chemical dispersant. During the performance of the test, the soil suspension is inspected visually to observe whether the suspension flocculates or remains stable. If flocculation occurs, despite the use of a dispersant, it is taken as an indication that the soil needs to be cleaned of excess soluble salts. This research was directed to study the interaction among the soil, the dispersant agent, and different soluble salts in a known and controlled environment. The results of this study show that visually apparent flocculation is just the last step in a process that starts affecting the results of the hydrometer analysis at much smaller salt concentrations than those corresponding to flocculation. These effects start taking place without any visual indication on the soil suspension. A method of screening soil samples that need to be cleaned is proposed based on the electrical conductivity of the pore water.