ISO 11461 pdf download

ISO 11461 pdf download.Soil quality — Determination of soil water content as a volume fraction using coring sleeves — Gravimetric method 1 Scope This International Standard specifies a method for the gravimetric determination of soil water content as a volume fraction. The method is applicable to all types of non-swelling or non-shrinking soils where coring sleeves can be used for sampling. It is not applicable to soils where stones, tough roots or other factors prevent collection of soil cores. It is used as a reference method (e.g. the calibration of indirect methods for determination of water content). NOTE The determination of water content as a mass fraction is described in ISO 1 1465. 2 Terms and definitions For the purposes of this International Standard, the following terms and definitions apply. 2.1 water content volume fraction volume of water evaporating from the soil when dried to constant mass at , divided by the original bulk volume of the soil NOTE The water content volume fraction is sometimes also referred to as “volumetric water content”. 2.2 constant mass mass reached when during the drying process the difference between two successive weighings of the sample, after a drying interval of , does not exceed (mass fraction) of the last determined mass NOTE Usually to is sufficient for drying most soils to constant mass, but certain soil types and large or very wet samples will require longer. 4 Principle Soil samples of known volume are dried to constant mass at . The difference in the mass of the soil sample, before and after the drying procedure, is taken as a measure of the water content. The water content is calculated as a volume fraction. NOTE Organic matter can oxidize during drying. This has no significant effect on the water content determined. However, drying at lower temperatures, e.g. , can lead to significantly lower values of the water content. Hence, drying at a temperature lower than is not recommended. 5 Apparatus 5.1 Drying oven, thermostatically controlled with forced air ventilation and capable of maintaining a temperature of . Differences in temperature between various positions in the oven shall be less than . NOTE By measuring the temperature at the centre of a sample during or directly after the drying procedure using a thin thermocouple with low thermal capacity, it is possible to determine whether the oven is working efficiently. These measurements should be carried out...