Physical and chemical properties of two Iranian peat types

Because peat has high organic content and high natural water content, it is potentially problematic for civil engineering projects involving construction on peatland. Therefore, it is important to understand the physical, chemical and geotechnical properties of the peat. The aim of the study reported here was to investigate the properties of two Iranian peat types. Peat and water samples were collected from sites within two extensive wetland areas (Chaghakhor Wetland and Gavkhuni Swamp) where construction works are planned. Both sites had peat layers more than three metres thick, which were sampled at depths of 0.6, 1.2, 1.8, 2.4 and 3.0 metres below ground level with four replicates per site. Degree of humification was determined in the field. Laboratory tests were conducted to determine the pH of water and peat; and the natural (field) moisture content, organic content, ash content, bulk density, dry density, density of solids, liquid limit, initial void ratio, linear shrinkage, unconfined compressive strength, shear strength and falling-head permeability of each peat sample. We also investigated the elemental compositions and microstructure of the peats using X-Ray fluorescence and scanning electron microscopy. The laboratory tests of physical and geotechnical properties indicated that, for construction purposes, Chaghakhor peat is weaker than Gavkhuni peat.