Laboratory investigation on the effects of pH-induced changes on geotechnical characteristics of clay soil.

This paper attempts to study the effects of acidic and alkaline waters on the geotechnical properties of a particular type of clay with low plasticity from the northeast areas of Isfahan that have been evaluated with pH values adjusted from 3 to 8. The remoulded specimens were placed in moulds under the influence of acid and alkaline rains with different pH values and years of precipitation. Atterberg limits tests, soil permeability coefficient, California bearing ratio (CBR) test and unconfined compressive strength (UCS) of soil specimens with various pH values were used to evaluate soil mechanical changes relative to soil with neutral acidity. In order to identify internal structural mechanisms of soil before and after artificial raining on the specimens, scanning electron microscopy and pH drainage tests of specimens were performed. The results of the interaction of rain and soil with shifting from neutral values were evaluated over a period of precipitation fluxes from 1 to 20 years. In overall, the more is the acidity or alkalinity of the artificial rain, the more will increase the Atterberg limits and the soil permeability compared to the soil specimens under artificial rain with pH = 7; and the decreasing trend is observed in UCS values and CBR. [ABSTRACT FROM AUTHOR]