Stabilization of Zeolite and Bentonite with Sewage Sludge Ash

Abstract

In this study, it is aimed to evaluate the wastewater sludge supplied locally at 100 tons/day in the investigation area. In this context, the geotechnical properties of bentonite, zeolite-type clays and sands, which are common in the investigation area, were determined by mixing with sewage sludge ash (SSA) in specified ratios. Grain size distribution and specific gravity of pure materials and mixtures were determined. Direct shear tests, permeability tests, consistency limits tests, modified proctor tests and PH determination tests were performed with the mixtures. Soils were mixed with 0.5, 7.5, 10 and 12.5 percent SSA in order to determine the physical, chemical and mechanical properties. Mixtures of sand with 40% bentonite (i.e., BS40) and sand with 40% zeolite (i.e., ZS40) were used as host materials for SSA inclusion. As a result of extensive laboratory studies, it was observed that the engineering properties of the specimens changed significantly as a result of the 7.5% and 12.5% mixture of SSA. BS40/SSA7.5 and ZS40/SSA12.5 samples from the mixtures reached 83 kPa and 80 kPa maximum shear strength under 200 kPa normal pressure. The maximum unit weight of specimens was achieved by BS40/S5 and ZS40/S5 specimens as 1.72 and 1.82 g/cm³, respectively. With the addition of SSA, the hydraulic permeability of the mixtures decreased to an order of 10E^–8 (cm/s) for BS40/SSA12.5 and ZS40/12.5 specimens. Experimental studies have provided significant engineering and environmental benefit in the evaluation of sewage sludge ash, which is inevitable in residential areas.