Abstract
Managing sediments dredged from reservoirs of recharge dams is an environmental issue, however, these sediments can be an abundant and economical source of fine-grained fill soil. This experimental investigation quantifies the geotechnical properties of a reservoir sediment used to improve engineering properties of a poorly graded dune sand in Oman. The binary mixes were prepared with different percentages (5, 10, 20, 50, 75, 90, 95%) of sediment with sand. Laboratory tests such as gradation, consistency limits, compaction, and unconfined compression tests were performed to measure the engineering characteristics of the binary mixtures. The results showed that the maximum dry density increases up to a sediment content of 50% and then decreases with further increase in the sediment content. The optimum water content increases with the increase in sediment content from 17% for pure sand to 22.5% for pure sediment. The optimum moisture content shows a good correlation with the plastic limit of the binary mixture of sand and sediment. The unconfined compressive strength substantially increases with sediment content up to 75% and then decreases with further increase in the sediment content. The binary mixture of sand sediment is sensitive to moisture, however, the order of strength stability against moisture is dune sand mixed with 75, 50, and 20% sediments. The addition of sediment to dune sand improved the uniformity coefficient to some extent with an increase in the maximum and minimum void ratios as well. The elemental analysis of the sediment confirms that the material is non-contaminated and can be employed in geotechnical engineering applications as a sustainable and environmentally friendly solution.
Highlights
Dune sands are characterized as collapsible soils and are not suitable for supporting infrastructure
This study provides detailed experimental results and the derived conclusions on using reservoir sediments to improve engineering properties of dune sands in Oman
The maximum and minimum void ratios of sand increased by adding sediments (Figure 3)
Summary
Dune sands are characterized as collapsible soils and are not suitable for supporting infrastructure. Dune sands are usually fine-grained and poorly graded materials (e.g., SP) with a small amount of silt [1], which need to be blended with additives to enhance their engineering properties to be appropriate for geotechnical engineering perspectives. The effectiveness of soil improvement depends on many factors, such as properties of the sand and the additive, field application method, environmental concerns, and economic feasibility. The utilization of waste material as an additive to improve the mechanical behavior of dune sand is expected to be an optimistic approach to reduce the carbon footprint associated with the processing of natural resources. Methods to remove the metals from dredged sediment [9,10] might be cumbersome and expensive. Alternative methods resulting in dredged sediments that retain heavy metals are urgently needed
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