Accession Number : AD0774863

Title :   An Evaluation of the Thermocouple Psychrometric Technique for the Measurement of Suction in Clay Soils.

Descriptive Note : Final rept.,


Personal Author(s) : Johnson,Lawrence D.

Report Date : JAN 1974

Pagination or Media Count : 81

Abstract : Suction or negative pore water pressure is important in controlling the physical properties of less than fully saturated soils. Methods for the accurate measurement of a wide range of suctions in such soils are not well known and are under development. This study to evaluate thermocouple psychrometers as a technique for the measurement of suction was initiated because these devices are relatively inexpensive, simple to use, allow rapid measurements, and possess a large range. Apparatus was designed, constructed, and tested for the thermocouple psychrometric measurement of suction pressure in clay soils without the need for precise temperature control. This report reviews the background literature leading to the development of the apparatus, describes the equipment, and outlines procedures for making psychrometric measurements. Suction measurements of Yazoo clay from Jackson, Mississippi, and clay from the weathered Upper Midway formation, Lackland Air Force Base, Texas, support the definition that total suction is the sum of matrix and osmotic components. (Modified author abstract)

Descriptors :   *Soil mechanics, *Clay, *Pore pressure, Hygrometers, Thermocouples

Subject Categories : Soil Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE