The paper presents a series of laboratory tests and evaluates the effect of lime and fly ash on the compressibility and hydraulic characteristics of an expansive soil in Cyprus. The tests were performed at different percentages of lime (0–7%) and fly ash (15 and 25%) by dry weight of soil, and additional tests were also performed on soils treated with 15% fly ash plus 3% lime. Previously published research reveals that few data are available concerning the compressibility and hydraulic conductivity of lime-treated soils. The results of this study indicate an increase in the vertical effective yield stress (apparent preconsolidation pressure) and a decrease in the compressibility characteristics of the treated soils. Moreover, unlike some of the findings in the literature, higher hydraulic conductivity values were obtained with time. This finding has been substantiated by the reduced cation exchange capacity (CEC) values, which indicate that the pozzolanic reaction causes the soils to become more granular in nature, resulting in higher hydraulic conductivity.Key words: cementation, compressibility, fly ash, hydraulic conductivity, lime.

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Abstrac~Previous applications of the method of known additions for quantitative X-ray fluorescent analysis have assumed a linear relationship between peak intensity and concentration of the element being analyzed. This assumption is true for soils or sediments containing small amounts of the element in question. In this paper, an equation is derived which takes into account both absorption and enhancement and thus is applicable to samples containing high concentrations of the element. The equation was tested by analyzing an artificial soil sample containing 60% kaolinite and 40% hematite, i.e. the sample contained 28% by weight iron. The fluorescent analysis utilizing the equation derived here resulted in an iron content of 27%. In addition, nine soils from Hawaii were analyzed by this method and the results of these analyses compared with analyses by atomic absorption. The agreement between the two methods is good. It is concluded that the method and equations proposed here provides a reliable measurement of elements in a soil sample which contains high concentrations of the elements in question.