Method to compare water content values determined on the basis of different oven-drying temperatures

The dry mass of a test specimen generally decreases for higher oven-drying temperatures as a result of small amounts of residual pore water evaporating from the void space (t < 100DGC), and some slight charring or slaking of the solid particles (t > 85DGC). Hence the apparent water content determined using the oven-drying method generally increases for higher oven-drying temperatures. The reductions in the dry masses of between 0.3% and 0.5% for the specimens of silt, clay and marl (ignition loss LOI, ratios less than 005) were not significant over the drying temperature range of 60-105DGC. Hence the water content values of these soils are, for practical purposes, independent of the oven-drying temperature used. However, the reductions in the dry masses of the shelly and organic marls and peats tested were significant, at up to 4.4% dry mass at 105DGC in the case of the peat material. Two methods were presented to relate and standardise water content values determined for the same material but on the basis of different oven-drying temperatures. The first method uses a water content parameter *a(sub t), defined as the ratio of the specimen dry masses at 105DGC and tDGC, and which is determined from a series of drying tests at different oven temperatures. The second method uses an empirical correlation based on the LOI ratio, and a sensitivity factor *b.