Geotechnical Properties for Mixed Materials of Sludge, Crushed Concrete, and Incineration Ash

Abstract

An effective use of limited space in existing waste disposal sites is highly needed due to the difficulty in constructing new facilities in Japan. The control of compaction and consolidation properties of waste materials is important to reduce disposal space. Correspondingly, studying on shear strength properties is essential in order to take precautionary measures against potential failures such as slope instability. In this study, geotechnical properties such as maximum dry density, compression index, and friction angle were investigated for mixed waste materials of sludge (D<2.0mm), crushed concrete (2.0mm<D<9.5mm), and incineration ash (D<2.0mm) with different mixing proportions. Mixed samples of sludge and crushed concrete and/or incineration ash showed almost same compaction characteristics and friction angle. However, completely different results between the mixed samples of sludge and incineration ash and the mixed samples containing crushed concrete were observed. The compression index was significantly decreased with decreasing the mixing proportion of sludge in case of adding the crushed concrete. Therefore, it is highly important to mix the crushed concrete for increasing the strength of waste materials.