# Use of Reservoir Sediments to Improve Engineering Properties of Dune Sand in Oman
## 1 Introduction  
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. Recently, it is strongly encouraged to reduce the carbon dioxide footprint in geotechnical engineering practices [2, 3]. 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. Reservoir sediments, a byproduct of weathering and erosion of rocks, are transported through alluvial process and get deposited in reservoirs of dams [4]. Oman has constructedseveral recharge dams to recharge groundwater from non-perennial flows and the sediments being deposited in the reservoirs are causing water infiltration reduction problems in situ [5]. Thus, reservoir bottom sediment dredging is performed periodically to remove thick sediments for maintenance purposes. However, the removal and disposal of dredged sediments requires considerable space as landfills and energy consumption during the dredging operations [6]. A primary factor that makes the concept of reusing the sediments a feasible solution is the potential economic benefits by cost-cutting of disposal and environmental issues related to the depletion of natural resources. In relation to this, an approach to determine the embodied energy and carbon dioxide contribution of ground improvement works has been developed [6; 7]. Dredged sediments are often polluted with contaminants, such as heavy metals [8; 9; 10]. Methods to remove the metals from dredged sediment [9; 10] might be cumbersome and expensive. Therefore, alternative methods resulting in dredged sediments that retain heavy metals are urgently needed. The construction and non-construction fill applications provide the greatest basis for reuse of sediments in the industrial sector. The sediments have been successfully employed as a useful resource such as fill material for road construction [11; 12], a mix of dredged sediment soil and steel slag fines for embankment construction in Singapore [13], construction material as mortars [14], clay material for island construction in Illinois, USA [15], and aggregates for concrete and masonry [16]. The municipal use of dredged material includes landfill capping [17] and beach nourishment. As stated in a study by [PERSON] et al. [18], \"the economic benefit of reusing dredged sediments is best realized when decreased costs of dredged sediment disposal are coupled with decreased costs of virgin material\". [PERSON] et al. [19] concluded that the treatment cost of dredged sediments in North-Western European ports ranges from 10 (slightly polluted) to 50 \(\ell\)/m\({}^{3}\) (heavily polluted) sediment in the populated and ecologically important areas. Therefore, the importance of utilizing the dredged sediments for engineering purposes cannot be ignored for the benefit of the society. According to [PERSON] et al. [20], the primary concern when utilizing dredged materials is to ensure that the materials to be placed are not more detrimental to the environment than traditional materials. The environmental issues associated with the use of dredged sediments are the potential for contamination and carbon footprint related to its reuse as an alternate resource in engineering applications. One of the possible re-uses of dredged fine sediments includes their use as an additive to improve the engineering properties of problematic dune sands. The addition of fines for improvement of engineering properties of poorly graded sands is a general practice in geotechnical engineering.