Feasibility of Using Sewage Sludge in Highway Embankment Construction.

摘要

A laboratory evaluation of the feasibility of using sewage sludge in construction of a highway embankment was conducted. Mixtures composed of lime,fly ash,waste calcium sulfate and up to 17% sewage sludge were evaluated. The effect of lime type,fly ash source and the relative proportions of lime,fly ash and waste calcium sulfate on compressive strength of compacted specimens was measured. Two soils,one sandy and the other clayey,were used to replace 30, 50and 70% of the fly ash in selected formulations. All samples with the soil replacement exceeded the minimum strength gain criterion. Selected formulations were further evaluated for volume change,durability,permeability and leachability. Analysis of the leachate from the permeability tests indicated that the heavy metals present in the sewage sludge--cadmium,chromium,mercury and zinc--were retained in the mixture. However,lime and gypsum did increase the pH and calcium and sulfate ion concentrations in the leachate.