Mineralogical characteristics and soil behaviour of lime-stabilised dredged sediment from Sengguruh Reservoir for sustainable fill applications

Abstract

Severe sedimentation in the Sengguruh Reservoir has reduced its effective storage capacity to approximately 24% of the original value, creating persistent dredging and spoil bank management problems. This study aimed to evaluate the potential reuse of dredged spoil bank sediment as sustainable fill material through lime stabilisation. Natural sediments and sediments treated with 10% and 15% calcium oxide on a dry weight basis were evaluated experimentally. Laboratory testing included specific gravity, grain-size distribution, Atterberg limits, soil classification based on USCS (unified soil classification system), USDA (United States Department of Agriculture), and AASHTO (American Association of State Highway and Transportation Officials) systems, soil activity analysis, and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDX) characterisation to identify mineralogical changes induced by stabilisation. The results showed that lime treatment substantially improved the sediment properties. Specific gravity increased from 2.493 in natural sediment to 2.645 at 15% lime, while the plasticity index decreased from 9.72% to 2.60%. Soil activity also declined – from 2.25 to 0.30, indicating reduced expansiveness and greater material stability. Under AASHTO, soil classification improved from A-5 to A-4, supporting its suitability for fill applications. The SEM–EDX analysis further revealed increased calcium content and reduced the relative abundance of aluminium and silicon, indicating pozzolanic reactions and mineralogical transformation toward more stable soil behaviour. The novelty of this study lies in integrating geotechnical index properties with mineralogical evidence to explain the stabilisation mechanism of reservoir dredged sediment. It demonstrated that 10–15% lime enables its beneficial reuse as a sustainable construction fill material.