Effect of fibre content on the geotechnical properties of peat

The purpose of the study was to determine the geotechnical properties of peat and relate them to the fibre content. Peat soil tested in this study was collected from the peatland in the north-eastern Poland, 250 km north-east of Warsaw. Peat samples were taken from eight different depths below the ground surface over an area of approximately 2500 m². The research programme consisted of laboratory tests of the physical properties of peat and compressibility tests conducted in oedometers. Tests were performed in accordance with the current international and European standards using specialised research equipment. Based on the degree of decomposition, peat was divided into fibric (with more than 66% of fibres), hemic (fibre content from 33% to 66%) and sapric (less than 33% of plant fibres). The bulk and particle densities, natural water content, organic content, initial void ratio and the degree of decomposition were investigated as the physical properties of peat. Based on the oedometer tests, the constrained modulus, compression and secondary compression indexes were determined. It was concluded that the fibric peat is characterised by the lowest bulk and particle densities, the highest water and organic contents, void ratio and compressibility in comparison to hemic and sapric peat. The characteristics of peat have been related to the results presented in the literature.