ENZYME INDUCED CARBONATE PRECIPITATION (EICP) TECHNIQUE USED FOR STABILIZATION OF PEAT
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Date
2026
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Publisher
National Institute of Technology,Silchar
Abstract
Peat poses severe geotechnical challenges due to its high organic content, excessive
compressibility, and extremely low shear strength. To overcome these geotechnical challenges
a sustainable bio-mediated stabilization techniques is used i.e. Enzyme-Induced Carbonate
Precipitation (EICP). This study aims to evaluate the effectiveness of EICP for stabilizing peat
and examining its strength improvement, durability behaviour and microstructural
modifications. EICP utilizes free urease enzyme extracted from soybean and urea–calcium
chloride cementation solutions at different concentrations of 0.75 M, 1.0 M, and 1.5 M leading
to precipitation of calcium carbonate (CaCO3) within peat. Laboratory investigations were
carried out to assess urease activity, compaction characteristics, unconfined compressive
strength (UCS), calcium carbonate content by Tube test and acid leaching test, pH, electrical
conductivity, microstructural analysis and durability test. EICP treatment enhanced the UCS
strength to a maximum value of 323 kPa, which is approximately 45 times higher than
untreated -peat at an optimum cementation concentration of 1.0 M after 28 days curing,
corresponding to a calcium carbonate content of approximately 29%. The maximum calcium
carbonate content (CCC%) of 32-33% was observed at 0.75M and 1M concentration. EICP
improved stiffness and durability, with microstructural observations of X-ray diffraction
(XRD) and field emission scanning electron microscopy (FESEM) confirming calcite bridging
in EICP-treated samples and enhanced particle aggregation.