field performance of many a lime-soil mix used as sub-base layers in the construction of road pavements has shown that such a layer starts deteriorating after some time. this weakening is more pronounced in the layer which is exposed either to upward fluctuations of the water table or infiltration of rain water. this is, in a large measure, attributed to the leaching of lime from the soil-lime layer. the effect of variants such as the curing period and the quantity of lime admixed on leaching and its consequent effect on the strength of the layer was studied. the leaching phenomenon was studied by performing permeability tests on two soils, a black cotton soil belonging to the montmorillonitic group and an alluvial soil of the illitic group. the soils were treated with different percentages of lime and the admixed samples were subjected to varying periods of curing. from the permeability tests conducted over a period of time, data was collectd to determine the influence of lime content and curing period on the leaching phenomenon. the studies show that the extent of leaching can be diminished if the lime-soil mix sample is subjected to a relatively longer period of curing. 9 refs