Effect of plastic fine and non-plastic fine on the compressibility behavior of granular material

The interaction between fine and sand grains has been studied by several researchers to evaluate the liquefaction phenomenon. However, the fine fraction effect on the compressibility behavior is less studied and requires more attention. A laboratory program was conducted to evaluate the effect of both non-plastic fines (silt) and plastic fine (clay) on the compressibility behavior of Chlef sand. The results show that the global void ratio ( e ) decreases with the increase of the fine content from 0 to 30% and then increases from 30 to 40% of the fine fraction for both mixtures (sand–silt and sand–clay). Inversely, the intergranular void ratio ( e s ) increases with the increase in the fine fraction. Moreover, increasing the fine percentage in the sand leads to an increase in the compressibility index ( C C ) and the granular compressibility index ( C c-s ). Our results indicate that the transition fine content depends on the stress level, the maximum void ratio ( e max ) calculated on the basis of some hypoplastic parameters model (granular hardness hs and exponent n ), and the nature of the fine content (clay or silt). Finally, the gradation parameters ( D 10 , D 50 , and C u ) have a significant effect on compressibility behavior.