Evaluation of the geotechnical properties of alum sludge, zeolite, and their mixtures for beneficial usage

In this article, the suitability of alum sludge (AS) for possible beneficial uses in geotechnical and geoenvironmental applications was investigated. The geotechnical properties (grain size distribution, index properties, compactibility, compressibility, hydraulic conductivity, and shear strength) of AS were determined. Considering the possible positive effects of zeolite (Z) on AS in terms of geotechnical properties and contaminant removal ability, AS was also mixed with various proportions of Z obtained from Manisa-Gördes, Turkey, and the engineering properties of Z and AS-Z mixtures were also determined. Odeometer test results showed that the samples were not highly compressible. For all the samples, low hydraulic conductivity values on the order of 10^-8 cm/s have been achieved. According to direct shear test results, cohesion (c) and internal friction angle (φ) values of the AS, Z, and AS-Z mixtures were within the ranges of c = 0-25 kPa and φ = 44°-37°, respectively. The geotechnical engineering tests conducted on the samples indicated that these materials were mechanically stable and could be used for various geotechnical and geoenvironmental applications.