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.

Abstract The results of three types of laboratory strength tests on undisturbed samples of a saturated clayey soil regolith are analyzed. Drained-direct shear tests, aniso-tropically consolidated-undrained triaxial compression tests with pore pressure measurement, and constant-shear-drained unloading test results indicate different modes of failure and different strength parameters. Based on the grain-size distribution and plasticity test results, it appears that the behavior and strength of the regolith would be dominated by the clay content; however, the results of the strength tests illustrate the soil has a structure formed by cemented bonds. This structure has a larger influence on the behavior and strength than the clay content does, at least at the depth of failure. At the in-situ stress level of the shallow regolith, the consequence of failure is found to be a function of the stress path. As a result, some slope failures may move slowly for short distances, and others many mobilize into rapid flow failures because of differences in the stress path leading to failure.