Effect of mica content and fineness on strength and compression properties of sands

In this effort, sand specimens with various percentages of 3 types of Mica contents and with different thicknesses were tested using oedometer tests and their oedometric behavior was investigated. Different ratios of L50/D50 were considered in specimen preparation and therefore the effects of Mica content and oedometric pressures on L50/D50 ratio were investigated. Normal stress was initiated from 1kPa and increased up to 1200kPa and then again unloaded to 1kPa. As a result, the variation of void ratio due to maximum plastic and elastic deformations are studied and regression formulas are presented to obtain the interparticle void ratio (es). It is observed that by increasing the L50/D50 ratio, specimens' compression is reduced. By increasing Mica content in the specimen, the initial settlements have increased, as also compressibility has increased. Increase of Mica content in the specimen has increased the interparticle void ratio. In compressive triaxial compression tests, poorly-graded sand specimens of S1 and S2 having no mica and with various percentages of Mica, under isotropic conditions and relative density of 30% were prepared and untrained consolidated triaxial tests have been performed under different consolidation effective pressures. The results are investigated for Mica contents of 0%, 10% and 20% under variation of deviatoric stress–axial deformation and pore water pressure – axial deformation are considered and eventually the effect of Mica content on specimens was studied. Increase of d50/D50 ratio has decreased the effect of Mica on the behavior of specimens. Increase of effective consolidation stresses has increased the effect of Mica content on specimens. Generally, by increasing Mica content of the specimens, the internal angle of friction has reduced. Also with the ratio of d50/D50=0.41, the specimen is hardened after failure due to water pressure modification and this event shows an improvement in the case of static liquefaction.