This International Standard specifies methods for the determination of the particle density in soils. This International Standard is applicable to the laboratory determination of the particle density of soil within the scope of geotechnical investigations, and describes two methods, a pycnometer method by fluid displacement and a pycnometer method by gas displacement. The fluid pycnometer method is based on the determination of the difference in the volume of liquid required to fill the pycnometer with and without the sample being present. The density of solid particles is calculated from the dry mass of the soil particles and the volume difference. The described fluid pycnometer method applies to soil types with particle sizes under about 4 mm, or soils crushed to meet this requirement. Larger pycnometers are used for coarser materials. The gas pycnometer method is based on the determination of the difference in the change in gas pressure, within the apparatus, between tests with the sample present and a reference test without a sample. The pressure difference is converted to a volume difference using Boyle s Law. The density of the particles is calculated from the dry mass of the sample and the volume difference. Particle size is limited by the dimensions of the specimen container of the particular gas pycnometer being used. NOTE This document fulfils the requirements of the determination of particle density of soils for geotechnical investigation and testing in accordance with EN 1997-1 and EN 1997-2.