LAUSR

Data obtained from previous soil borings revealed that, natural soils free of fines are rarely encountered in the field. On this basis, the aim of this study is to investigate the effects of plastic fines on mechanical behavior of sand (quartz)-clay mixtures. Two types (bentonite and kaolinite) of clay were mixed with quartz at rates ranging among 0% to 100% by dry weight. Evaluations were made based on changes in threshold fines content (FCt) with clay type and mechanical properties, consistency limits, and compaction characteristics. The results indicate that undrained shear strength (su) decreased up to 30% kaolinite content while increased with bentonite content from 0 to 100% which is an evidence of the effect of clay type on FCt. Furthermore, quartz-kaolinite mixtures have greater maximum dry unit weight that quartz-bentonite mixtures. On the contrary, the undrained shear strength of quartz-bentonite mixtures was greater than quartz-kaolinite mixtures.