Effect of Fines Content on Liquefaction Susceptibility of Sand-Kaolin Mixtures

Recent empirical observations reveal that not only the clean sand is susceptible to liquefaction hazard, both silty sand and clayed sand are also liquefiable. This paper presents the cyclic behaviour of sand-fines mixtures at various fines content. The sand-fines specimens were reconstituted by mixing clean sand with different percentages of plastic fines (kaolin) by weight to a constant relative density of 20 % using dry tamping method. The specimen had been tested with stress controlled cyclic triaxial test under consolidated undrained condition with effective confining pressure of 100 kPa, cyclic load of 0.1 kN and cyclic frequency of 0.5 Hz. The results show that the liquefaction resistance of sand matrix soils increased as fines content increased from 0 to 25 %, whereas this trend was reversed for value of fines content greater than 25 %. In fact, the 25 % of kaolin by weight is also the threshold fines content of sand-kaolin mixtures. Hence this finding justifies that the concept of fines threshold content could be used to significantly explain the influence of fines content on the liquefaction susceptibility of sand-fines mixtures.