The effects of clay on the geotechnical properties of oil-sands tailings deposits are discussed. The sources of fluid fine tailings are reviewed, and types of tailings deposits are described. The effects of clay on geotechnical index properties, hydraulic conductivity, compressibility, and shear strength are discussed, with example predictions for consolidation and strength gain in fines-enriched sand tailings and deep fines-dominated tailings deposits.

Abstract Residual sludge from dimension-stone working plants, both from gangue saws with abrasive shot and frame saws, is classified as waste and presents a number of problems for the stone industry. These problems include a fine size distribution, heavy metals and total petroleum hydrocarbon (TPH) content, all of which impede recovery and reuse. Residual sludge, management of which is administered in accordance with the Italian Legislative Decree 152/06, can be used in waste form for environmental restoration or for cement plants. However, it is also possible that sludge applications could go beyond these limited uses with incorporation of systematic treatment for the production of secondary raw materials (SRM), for example, filler, or for ‘new products’, for example, artificial loam. Such new products or SRM have to be certified not only on the basis of their technical and physical characteristics but also by means of appropriate chemical analyses to guarantee that the products are not contaminated. This paper outlines the results from laboratory and in situ characterization of residual sludge. In particular, three potential applications of sludge either by itself or mixed with other materials were evaluated: landfill waterproofing material, filler material for civil works and artificial soil for land rehabilitation.