Browsing by Author "Deori, Teenamoni"

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    STABILIZATION OF PEAT USING CALCIUM LIGNOSULFONATE AND RICE HUSK ASH
    (National Institute of Technology, Silchar, 2026) Deori, Teenamoni
    Peat is viewed as one of the most troublesome geomaterials for use in construction because it is highly organic, highly compressible, and possesses extremely low shear strength, resulting in poor engineering performance and excessive settlement. This study aims to utilize lignin based biopolymer calcium lignosulfonate (CLS) and rice husk ash (RHA) to overcome these challenges. CLS concentrations of 0, 3, 5, and 7% by dry weight of peat were used, while RHA was used as an additional filler at concentrations of 10, 20, and 30%. Laboratory investigations were conducted to evaluate the compaction characteristics, unconfined compressive strength (UCS), pH, electrical conductivity (EC), and durability through wetting-drying (W-D) cycles. Test results indicated that the maximum dry density (MDD) increased due to improved particle aggregation and better packing of the treated peat matrix, along with a slight reduction in optimum moisture content (OMC). A significant improvement in UCS of about 497.02 kPa and 300.5 kPa was achieved at an optimum CLS content of 5% and 20% RHA, respectively, whereas a UCS of 506.28 kPa was achieved by combining both stabilizers at an optimum CLS content of 5% and 20% RHA. Compared to natural untreated peat, which showed a strength of only 7.59 kPa, the addition of CLS and RHA resulted in strength gains of 66-fold and 40-fold, respectively. Meanwhile, the combined effect increased the strength by about 68-fold. This study also demonstrates the variation in elastic modulus (E50) with respect to UCS for both stabilizers. Durability experiments, however, indicated a progressive loss of strength with an increasing number of wetting-drying cycles as a result of mass loss and destabilization of calcium silicate hydrate (CSH) gel. The tests revealed that, after three cycles, visible deterioration and breakage occurred. Furthermore, microstructural analyses using X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), and Energy Dispersive X-ray Spectroscopy (EDX) confirmed peat aggregation and particle densification, which were responsible for the observed strength gain in peat.