Evaluating the compression index of fibrous peat treated with different binders

Fibrous peats feature high compressibility and correspondingly very low strength. In this study, an investigation into the compressibility of untreated and stabilized fibrous peat with different binders—namely cement, lime, gypsum, and fly ash—is presented. The technique adopted for sample preparation was aimed at simulating the in-situ condition of the deep soil mixing technique. For this purpose, the binder dosages were selected in the range of 100–400 kg/m³ of wet fibrous peat at its natural water content. This binder range was determined based on the unconfined compressive strength of the treated samples. All the treated samples were cured for 14, 28, and 90 days in both air and water. The consolidation behavior of the treated peat samples was assessed by performing a Rowe cell consolidation test. The test results revealed that the increase in cement, fly ash, and gypsum contents led to considerable decreases in compression indices of the treated fibrous peat. No significant changes in the compressibility properties of lime-treated peat were observed. In addition, the inclusion of well-graded sand as filler decreased the compression indices of the treated samples significantly. Finally, in comparison with air curing, the use of the water curing technique for all the stabilized samples, regardless of binder type, showed better performances.