The Effect of Coarse Fiber on Long-Term Compression of Tropical Fibrous Peat in Indonesia

Peat is organic soil composed of fragmented and decomposed plant materials. This soil has a short period of primary compression and followed by significant secondary compression. However, a comprehensive study about the long-term compression behavior of peat is still limited, especially for tropical fibrous peat. Tropical fibrous peat generally consists of stems, roots, and leaves from woody plants. Stem has a high contained of lignin, hence more difficult to decompose and stiffer than other parts of woody plants. Thus, pieces of the stem are often found as the main component of coarse fiber on tropical fibrous peat. The aim of this study is to assess the effect of coarse fiber content increment on the long-term compression behavior of tropical fibrous peat in Indonesia. Peat samples were taken from Palangkaraya (Central Kalimantan), Kampar (Riau), and Serdang Bedagai (North Sumatra). A one-dimensional consolidation test was conducted by using the increment loading method. The result shows that Central Kalimantan, Riau, and North Sumatra peat studied has coarse fiber content of 17.35%, 7.11%, and 54.40%, respectively. The long-term compression curve of Central Kalimantan peat exhibits an S-shape (typical of clay). While the shape tends to deviate to be straight line for peat from Riau and North Sumatra. The amount of coarse fiber influences the rate of secondary compression value significantly in the last load increment (100–200 kPa).