Water content determinations for peat and other organic soils using the oven-drying method

Abstract

There has been much debate in literature over the past 60 years regarding an appropriate oven-drying temperature for water content determinations on peat and other organic soils. For inorganic soils, the water content is usual based on the equilibrium dry mass corresponding to drying temperatures in the range 100?110oC. However, for peat and other organic soils, several researchers have recommended lower drying temperatures in the range 60?90oC in an attempt to prevent possible charring, oxidation and (or) vaporization of substances other than pore water. However, all of the relevant water is not fully evaporated at too low a temperature, and since specimen dry mass is a function of drying temperature, resulting water content values are lower than those determined for the temperature range 100?110oC. Experimental data reported in this paper show that oven drying of peat and other organic soils at 100?110oC using either gravity?convection or forced-draft ovens is acceptable for routine water content determinations. Since a standardized oven temperature is desirable when correlating water content with other material properties, it is recommended that oven drying of peat and other organic soils be performed over temperature ranges of either 105?110?C or 105?5?C, in line with standardized ranges for inorganic soils.