PHYSICAL AND MECHANICAL PROPERTIES OF FINE GRAINED SOILS TREATED BY FLUIDAL FLY ASH Karolina Knapik, Joanna Bzówka The Silesian University of Technology University of Cassino and Southern Lazio karolina.knapik@polsl.pl, joanna.bzowka@polsl.pl Giacomo Russo, Paolo Croce, Giuseppe Modoni University of Cassino and Southern Lazio giarusso@unicas.it, croce@unicas.it, modoni@unicas.it Summary The present work is focused on the investigation of physical and mechanical properties of fine grained soil treated with selected fly ash and lime in order to observe the effects that mixtures prepared with different component proportions induce on the observed behavior. The experimental investigation was carried out on Speswhite kaolin treated with fly ash coming from fluidized bed combustion and lime. pH measurements, sedimentation tests and oedometer tests were performed in order understand the mechanisms governing the physical and mechanical behavior of the treated soils. 1. Introduction Fly ash is a waste material obtained during the energy production in power plants. In countries such as Poland where energy industry is based almost entirely on power plants and thermal power plans operation, the reuse of waste material represents an alternative and economical solution with respect to its disposal. Therefore this involves the need to identify the properties of fly ash originating from a particular power plant, working on raw material mined in a specific location. Currently fly ash is a worldwide object of interest of scientific units also in terms of its use in geotechnical engineering. Literature describes a beneficial effect of the fly ash addition (also in combination with lime or cement) on fine grained soils properties. These benefits includes among the others decrease of free swelling (Zhang and Cao 2002) and increase of strength and stiffness of the treated soils (Reyes and Pando 2007, Kolias et al. 2005). The aim of this paper is to show the present stage of an experimental work, concerning the reuse of fly ash, selected from a polish power plant as an alternative solution of ground improvement technique. 2. Materials and procedures The soil chosen for the present investigation was Speswhite Kaolin, whose properties are summarized in Table1and 2. The fluidal fly ash were provided by a power plant placed in Silesia region (Poland). Chemical composition and grain size distribution of fly ash are given in Table 3 and Figure 1.