The effect of lead on the engineering properties of CH soils in Najmabad industrial towns in Alborz province

One of the most important problems that different societies have always faced in recent years is the pollution of water and soil by heavy metals. The main source of penetration of these metals in the environment is the activity of industrial factories and estates. This is not only an environmental problem but also it is comprehensively discussed in engineering. The penetration of heavy metals into the soil can change some of the physical and mechanical properties of the soil. In this study the effect of lead nitrate on geotechnical parameters of CH soil in Najmabad industrial town in Alborz province in Iran was investigated. the processing time of contaminated samples was considered to be ۷۲ hours and different concentration of lead solution used to contaminate the soil are ۱۰۰۰, ۲۰۰۰ and ۵۰۰۰ ppm. Based on the result in the clay soils with high plasticity by increasing the concentration of lead in the soil, the liquid limit and plastic limit of the soil decreased, the maximum dry density increased, the optimum water content decreased and the cohesion of soil increased. By increasing the concentration of lead in the soil the angle of internal friction of the soil does not change regularly and significantly but the soil porosity ratio is reduced.