Drying temperature and water content–strength correlations

Abstract

For water content determinations on organic soils, several researchers have adopted lower oven-drying temperatures in the range 35−90°C (instead of the standardised range for mineral soils of 100–110°C) in order to prevent possible charring, oxidation and (or) vaporisation of substances other than water. However, at too low a temperature, not all of the relevant water is driven off. One major consequence of using such a wide range of drying temperatures for more sensitive materials is to produce considerable disparity in interpolated index values and in deduced correlations between water content and other engineering properties. This paper discusses the pros and cons regarding the oven-drying temperature adopted for routine water content determinations on organic sludges and residues. It concludes by recommending a standardised oven temperature of 105–110°C or 105 ± 5°C, a 24-h drying period and a suggested minimum wet specimen mass of 50 g.