Performance of Pavement Subgrade Using Fly ash Stabilized Peat Soil Reinforced with Nylon Fiber

Peat is a highly soft soil that possesses low shear strength due to the presence of organic content and a high amount of moisture content. In the present study, the peat is stabilized to enhance the strength with fly ash with different percentages of 3, 6, 9, 12, and 15% and reinforced with nylon fiber with 0.5, 1.0 and 1.5% to investigate the performance of peat. The strength of fly ash and fiber-treated peat is compared with cement-treated peat. The Compaction, California bearing ratio (CBR), Unconfined compressive strength (UCS) and Unconsolidated Undrained Triaxial (UU Triaxial), Freezing & Thawing (F & T) tests were used for evaluating the strength properties of peat. The UCS value increases to 280 kPa from 60 kPa at 12% of fly ash content, but at 15% cement content it was increased up to 370 kPa. The UCS value of peat stabilized with 12% of fly ash and reinforced with 1% of fiber obtained as 360 kPa. The CBR also increased to 9.3 from 2.5% for stabilized peat (12% fly ash) and reinforced fiber (1%) in soaked condition whereas the CBR value increases up to 9.7% for the case of 15% cement content. It is observed from the freezing and thawing tests, the strength of fly ash stabilized peat-reinforced fiber is decreased by 50%. Whereas the cement-stabilized peat is reducing its strength by 30%. Therefore, 15% of cement can be replaced with 12% of fly ash and 1% of nylon fiber together to make the stabilization effective in normal conditions, but not durable for weathering actions compared to cement-treated peat. The pavement thickness is evaluated from CBR value and observed that the stabilized peat-reinforced fiber significantly affects the thickness of the pavement.