Effect of Dates Nucleus Powder on Some Enginerring Properties of Clayey Soil in Comparison to Lime

Abstract

Clayey soils are widely spread over the world. The clay soils are used and need to improve it's engineering properties.Therefore, the treatment is considered one of the available solution for this purpose. Due to the nature of clay particles a trice plasticity,highly in surface area and the ion exchangaple ...etc. these properties encourage the idea of using pozzolanic materials, particularly the lime as pozzolana source.The alternative source of pozzolan is a metakaolin materials generated from burning the organic materials which are widely available in Iraq (i.e. Dates nucleus). The Dates nuclei is a waste material, so these additives can help in reducing the contamination and improving the environment. In this study, dates nuclei powder (DNP) was used after burning it at 900 o C for one hour and then mixed it with clayey soil in different by weight percentages. Hence, four percentages are selected (5%, 7.5%, 10%, and 15%) to study the effect of each addition on the shear strength of the clayey soil and the results are compared with the same soil that treated with lime. Many tests were conducted on (the natural clay, clay-DNP and clay-lime) to evaluate the engineering characteristics and to explore best percentages that can used. Curing time (0, 7, 14, 28,90 and 180 days) was used to evaluate the effectiveness of pozzolanic reaction (emerges from DNP-soil mixture) with time. Interested results are found, the shear strength was increased to about six folds for 10%-DNP-soil at 180 days of curing. The liquid limit, plasticity index and the maximum dry density decreased in all percentages of DNP-Clay mixtures. On the other hand, the shear strength increment for DNP-Clay mixture after 180 days of curing is higher than that of Lime-Clay mixture for same period of curing. Forthermore, CBR results increased by six times for 10%DNP-Clay mixture for un-soaking conditions, while at soaking conditions, the increase was more than eleven times. The lime addition increase the CBR-value about three and eight times for unsoaking and soaking conditions, respectively.