This study investigates the sustainable use of seabed dredged sediments and water treatment sludges as construction materials using combined dewatering and cement stabilization techniques. Dredged sediments and water treatment sludges, typically considered waste, were evaluated for their suitability in construction through a series of dewatering and stabilization processes. Dewatering significantly reduced the initial moisture content, while cement stabilization improved the mechanical properties, including strength and stiffness. The unconfined compressive strength (UCS), shear modulus, and microstructural changes were evaluated using various analytical techniques, including unconfined compression testing, free-free resonance testing, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The results show a direct correlation between reduced w/c ratios and increased UCS, confirming the potential of treated sludge as a subbase layer for roads and landfill liners. A chemical analysis revealed the formation of calcium silicate hydrate (CSH) and ettringite, which are critical for strength enhancement. This approach not only mitigates the environmental issues associated with sludge disposal but also supports sustainable construction practices by reusing waste materials. This study concludes that cement-stabilized dredged sediments and water treatment sludges provide an environmentally friendly and effective alternative for use in civil engineering projects.

This study aims to enhance the suitability of expansive clayey soils for use as landfill liners by incorporating water treatment sludge ash (WTSA). Expansive soils, prone to swelling and desiccation cracking, compromise landfill liner integrity, increasing the risk of groundwater contamination. Local soils often do not meet the requirements for hydraulic conductivity and stability, prompting the use of additives like bentonite. However, bentonite-treated soils still face challenges in tropical regions due to moisture loss and cracking. This research investigates the effects of adding WTSA to bentonite-treated soils to mitigate swelling and shrinkage issues. Several geotechnical tests were conducted, including hydraulic conductivity, free swell percentage, swelling pressure, volumetric shrinkage, and desiccation cracking. Results show that WTSA significantly reduces hydraulic conductivity, free swell percentage, and swelling pressure, meeting the standard requirements for liners (hydraulic conductivity of at least 1x10-9 m/s and volumetric shrinkage of at least 4%). Moreover, WTSA addition reduces desiccation cracking to acceptable levels, demonstrating its potential as an effective reinforcement material. This study introduces an innovative approach to using WTSA, a waste product, as a sustainable alternative to conventional liner materials, reducing environmental impact and enhancing landfill liner performance.

In small settlements, collectors for the sludge produced during water treatment processes are small-sized and located in the vicinity of drinking water storage reservoirs or in coastal areas. Sludge removal is not economical. Besides, the relief depressions formed after sludge disposal are required to be reclaimed. In ore mining regions, where the main settlements of the Urals are located, sludge produced in water treatment has high contents of heavy metals typical of ore mining provinces. Consequently, places of sludge accumulation are potential sources of water pollution. The article discusses the possibility to mix sludge with slaked lime and local overburden with the help of special equipment. So far water treatment sludge in the region has been used to reclaim the surface of solid waste landfills by creating anaerobic conditions for waste decomposition. When placed inside the embankment dams as an independent object, sludge needs to be improved for the increase of its bearing capacity and the ability to bind heavy metals. The article aims at the substantiation of the composition and properties of the reclamation material made of the water treatment sludge mixed with local overburden and slaked lime (technosoil). For this reason the paper describes the composition of the sludge in a sludge collector, the composition and properties of the overburden rocks as a component of the mixtures with water treatment sludge, the composition and properties of the mixtures of water treatment sludge with overburden rocks and Ca(OH) (2) as a component dewatering sludge and neutralizing toxicants. Furthermore, the research work provides the technology created for the optimal processing of the water treatment sludge in the process of the reclamation of a sludge collector. The research results and the experience obtained in reclamation of disturbed lands in the region have confirmed the possible use of technosoil for the reclamation of small-capacity sludge collectors. The analysis of the chemical composition and physical and mechanical properties of the mixtures under study has shown that the most economical and environmentally sound reclamation material is a mixture of water treatment sludge, loose overburden dump soils and Ca(OH) 2 in a ratio of 60 : 30 : 10 %.