Silts and silt-clay mixtures are found in several parts of the world. Their liquefaction behavior during
earthquakes has not been critically examined as compared with the liquefaction behavior of clean sands.
However it has been observed that, if a sand-fines mixture has the same standard penetration value (N1)60 as the
clean sands, the addition of fines increases its liquefaction resistance (Seed et al. 1985). This has led to an
erroneous belief that the addition of fines to sands increases their liquefaction resistanceand therefore, addition
of clays to silts will also increase their liquefaction resistance. However, Troncoso (1990) established that if
fines are added to sands, their resistance to liquefaction decreases if the soils are tested at the same void ratio.
Neither Troncoso (1990) nor Seed et al. (1985) describe the plasticity characeristics of fines in the sand.