Behavioral Change of the Bacterially Decomposed Fibrous Tropical Peat Stabilized with Lime CaCO3 and Fly Ash

Peat is an organic soil with an organic content of more than 75%; it is called fibrous peat if it has a fiber content of more than 20%. In general, fibrous peat has very low bearing capacity and very high compressibility. By mixing with 10% stabilizer material (30% lime CaCO3 and 70% fly ash), the bearing capacity of fibrous tropical peat increases significantly. After 45 days of curing, however, its bearing capacity drops significantly. It was found that the fibrous tropical peat-bearing capacity decrement was caused by the fiber size change (fiber decomposition). Therefore, the peat fibers must be decomposed before the stabilization is carried out to get the optimal result. For this purpose, the fibrous tropical peat was decomposed by using 10% (by wet weight) of lignocellulolytic decomposer bacteria and cured in 28 days; the result showed that most of the coarse fibers changed to fine fibers. Afterward, the next step of the study was determining the amount of stabilizer material that was able to improve the behavior of the bacterially decomposed fibrous tropical peat. For this purpose, the decomposed fibrous tropical peat was stabilized with 5, 10, and 15% stabilizer materials and cured within 90 days. The results show that its behavior improvement occurs with the increase of the amount of stabilizer materials; a significant increment occurs when the stabilizer material used is 10% with 60 days of curing periods. Based on this study result, it is recommended to use 10% (by wet weight) of stabilizer material and 60 days of curing to increase the bearing capacity of bacterially decomposed fibrous tropical peat.